Identification and engineering of antibodies with variant Fc regions and methods of using same

[0001] This application claims priority to U.S. Provisional Application Ser. No. 60/707,419, filed on Aug. 10, 2005, which is hereby incorporated by reference herein in its entirety.

[0002] The present invention relates to molecules, particularly polypeptides, more particularly immunoglobulins (e.g., antibodies), comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, which variant Fc region binds FcγRIIIA and/or FcγRIIA with a greater affinity, relative to a comparable molecule comprising the wild-type Fc region. The molecules of the invention are particularly useful in preventing, treating, or ameliorating one or more symptoms associated with a disease, disorder, or infection. The molecules of the invention are particularly useful for the treatment or prevention of a disease or disorder where an enhanced efficacy of effector cell function (e.g., ADCC) mediated by FcγR is desired, e.g., cancer, infectious disease, and in enhancing the therapeutic efficacy of therapeutic antibodies the effect of which is mediated by ADCC.

[0003] 2.1 Fc Receptors and their Roles in the Immune System

[0004] The interaction of antibody-antigen complexes with cells of the immune system results in a wide array of responses, ranging from effector functions such as antibody-dependent cytotoxicity, mast cell degranulation, and phagocytosis to immunomodulatory signals such as regulating lymphocyte proliferation and antibody secretion. All these interactions are initiated through the binding of the Fc domain of antibodies or immune complexes to specialized cell surface receptors on hematopoietic cells. The diversity of cellular responses triggered by antibodies and immune complexes results from the structural heterogeneity of Fc receptors. Fc receptors share structurally related ligand binding domains which presumably mediate intracellular signaling.

[0005] The Fc receptors, members of the immunoglobulin gene superfamily of proteins, are surface glycoproteins that can bind the Fc portion of immunoglobulin molecules. Each member of the family recognizes immunoglobulins of one or more isotypes through a recognition domain on the a chain of the Fc receptor. Fc receptors are defined by their specificity for immunoglobulin subtypes. Fc receptors for IgG are referred to as FcγR, for IgE as FεR, and for IgA as FcαR. Different accessory cells bear Fc receptors for antibodies of different isotype, and the isotype of the antibody determines which accessory cells will be engaged in a given response (reviewed by Ravetch J. V. et al. 1991, Annu. Rev. Immunol. 9: 457-92; Gerber J. S. et al. 2001 Microbes and Infection, 3: 131-139; Billadeau D. D. et al. 2002, The Journal of Clinical Investigation, 2(109): 161-1681; Ravetch J. V. et al. 2000, Science, 290: 84-89; Ravetch J. V. et al., 2001 Annu. Rev. Immunol. 19:275-90; Ravetch J. V. 1994, Cell, 78(4): 553-60). The different Fc receptors, the cells that express them, and their isotype specificity is summarized in Table 1 (adapted from Immunobiology: The Immune System in Health and Disease, 4^th ed. 1999, Elsevier Science Ltd/Garland Publishing, New York).

[0006] Fcγ Receptors

[0007] Each member of this family is an integral membrane glycoprotein, possessing extracellular domains related to a C2-set of immunoglobulin-related domains, a single membrane spanning domain and an intracytoplasmic domain of variable length. There are three known FcγRs, designated FcγRI(CD64), FcγRII(CD32), and FcγRIII(CD16). The three receptors are encoded by distinct genes; however, the extensive homology between the three family members suggest they arose from a common progenitor perhaps by gene duplication.

[0008] FcγRII(CD32)

[0009] FcγRII proteins are 40 KDa integral membrane glycoproteins which bind only the complexed IgG due to a low affinity for monomeric Ig (10⁶ M⁻¹). This receptor is the most widely expressed FcγR, present on all hematopoietic cells, including monocytes, macrophages, B cells, NK cells, neutrophils, mast cells, and platelets. FcγRII has only two immunoglobulin-like regions in its immunoglobulin binding chain and hence a much lower affinity for IgG than FcγRI. There are three human FcγRII genes (FcγRII-A, FcγRII-B, FcγRII-C), all of which bind IgG in aggregates or immune complexes.

[0010] Distinct differences within the cytoplasmic domains of FcγRII-A and FcγRII-B create two functionally heterogenous responses to receptor ligation. The fundamental difference is that the A isoform initiates intracellular signaling leading to cell activation such as phagocytosis and respiratory burst, whereas the β form initiates inhibitory signals, e.g., inhibiting B-cell activation.

[0011] Signaling Through Fcγs

[0012] Both activating and inhibitory signals are transduced through the FcγRs following ligation. These diametrically opposing functions result from structural differences among the different receptor isoforms. Two distinct domains within the cytoplasmic signaling domains of the receptor called immunoreceptor tyrosine based activation motifs (ITAMs) or immunoreceptor tyrosine based inhibitory motifs (ITIMS) account for the different responses. The recruitment of different cytoplasmic enzymes to these structures dictates the outcome of the FcγR-mediated cellular responses. ITAM-containing FcγR complexes include FcγRI, FcγRIIA, FcγRIIIA, whereas ITIM-containing complexes only include FcγRIIB.

[0013] Human neutrophils express the FcγRIIA gene. FcγRIIA clustering via immune complexes or specific antibody cross-linking serves to aggregate ITAMs along with receptor-associated kinases which facilitate ITAM phosphorylation. ITAM phosphorylation serves as a docking site for Syk kinase, activation of which results in activation of downstream substrates (e.g., PI₃K). Cellular activation leads to release of proinflammatory mediators.

[0014] The FcγRIIB gene is expressed on B lymphocytes; its extracellular domain is 96% identical to FcγRIIA and binds IgG complexes in an indistinguishable manner. The presence of an ITIM in the cytoplasmic domain of FcγRIIB defines this inhibitory subclass of FcγR. Recently the molecular basis of this inhibition was established. When colligated along with an activating FcγR, the ITIM in FcγRIIB becomes phosphorylated and attracts the SH2 domain of the inosital polyphosphate 5′-phosphatase (SHIP), which hydrolyzes phosphoinositol messengers released as a consequence of ITAM-containing FcγR-mediated tyrosine kinase activation, consequently preventing the influx of intracellular Ca⁺⁺. Thus crosslinking of FcγRIIB dampens the activating response to FcγR ligation and inhibits cellular responsiveness. B cell activation, B cell proliferation and antibody secretion is thus aborted.

TABLE 1
Receptors for the Fc Regions of Immunoglobulin Isotypes
	FcγRI	FcγRII-A	FcγRII-B2	FcγRII-B1	FcγRIII		FcαRI
Receptor	(CD64)	(CD32)	(CD32)	(CD32)	(CD16)	FcεRI	(CD89)
Binding	IgG1	IgG1	IgG1	IgG1	IgG1	IgE	IgA1, IgA2
	108 M−1	2 × 106 M−1	2 × 106 M−1	2 × 106 M−1	5 × 105 M−1	1010 M−1	107 M−1
Cell Type	Macrophages	Macrophages	Macrophages	B cells	NK cells	Mast cells	Macrophages
	Neutrophils	Neutrophils	Neutrophils	Mast cells	Eosinophil	Eosinophil	Neutrophils
	Eosinophils	Eosinophils	Eosinophils		Macrophages	Basophils	Eosinophils
	Dendritic cells	Dendritic cells			Neutrophils
		Platelets			Mast Cells
		Langerhan cells
Effect of	Uptake	Uptake	Uptake	No uptake	Induction of	Secretion of	Uptake
Ligation	Stimulation	Granule release	Inhibition of	Inhibition of	Killing	granules	Induction of
	Activation of		Stimulation	Stimulation			killing
	respiratory burst
	Induction of
	killing

[0015] 2.2 Diseases of Relevance

[0016] 2.2.1 Cancer

[0017] A neoplasm, or tumor, is a neoplastic mass resulting from abnormal uncontrolled cell growth which can be benign or malignant. Benign tumors generally remain localized. Malignant tumors are collectively termed cancers. The term “malignant” generally means that the tumor can invade and destroy neighboring body structures and spread to distant sites to cause death (for review, see Robbins and Angell, 1976, Basic Pathology, 2d Ed., W.B. Saunders Co., Philadelphia, pp. 68-122). Cancer can arise in many sites of the body and behave differently depending upon its origin. Cancerous cells destroy the part of the body in which they originate and then spread to other part(s) of the body where they start new growth and cause more destruction.

[0018] More than 1.2 million Americans develop cancer each year. Cancer is the second leading case of death in the United States and if current trends continue, cancer is expected to be the leading cause of the death by the year 2010. Lung and prostate cancer are the top cancer killers for men in the United States. Lung and breast cancer are the top cancer killers for women in the United States. One in two men in the United States will be diagnosed with cancer at some time during his lifetime. One in three women in the United States will be diagnosed with cancer at some time during her lifetime.

[0019] A cure for cancer has yet to be found. Current treatment options, such as surgery, chemotherapy and radiation treatment, are oftentimes either ineffective or present serious side effects.

[0020] Cancer Therapy

[0021] Currently, cancer therapy may involve surgery, chemotherapy, hormonal therapy and/or radiation treatment to eradicate neoplastic cells in a patient (See, for example, Stockdale, 1998, “Principles of Cancer Patient Management”, in Scientific American: Medicine, vol. 3, Rubenstein and Federman, eds., Chapter 12, Section IV). Recently, cancer therapy could also involve biological therapy or immunotherapy. All of these approaches pose significant drawbacks for the patient. Surgery, for example, may be contraindicated due to the health of the patient or may be unacceptable to the patient. Additionally, surgery may not completely remove the neoplastic tissue. Radiation therapy is only effective when the neoplastic tissue exhibits a higher sensitivity to radiation than normal tissue, and radiation therapy can also often elicit serious side effects. Hormonal therapy is rarely given as a single agent and although can be effective, is often used to prevent or delay recurrence of cancer after other treatments have removed the majority of the cancer cells. Biological therapies/immunotherapies are limited in number and may produce side effects such as rashes or swellings, flu-like symptoms, including fever, chills and fatigue, digestive tract problems or allergic reactions.

[0022] With respect to chemotherapy, there are a variety of chemotherapeutic agents available for treatment of cancer. A significant majority of cancer chemotherapeutics act by inhibiting DNA synthesis, either directly, or indirectly by inhibiting the biosynthesis of the deoxyribonucleotide triphosphate precursors, to prevent DNA replication and concomitant cell division (See, for example, Gilman et al., Goodman and Gilman's: The Pharmacological Basis of Therapeutics, Eighth Ed. (Pergamom Press, New York, 1990)). These agents, which include alkylating agents, such as nitrosourea, anti-metabolites, such as methotrexate and hydroxyurea, and other agents, such as etoposides, campathecins, bleomycin, doxorubicin, daunorubicin, etc., although not necessarily cell cycle specific, kill cells during S phase because of their effect on DNA replication. Other agents, specifically colchicine and the vinca alkaloids, such as vinblastine and vincristine, interfere with microtubule assembly resulting in mitotic arrest. Chemotherapy protocols generally involve administration of a combination of chemotherapeutic agents to increase the efficacy of treatment.

[0023] Despite the availability of a variety of chemotherapeutic agents, chemotherapy has many drawbacks (See, for example, Stockdale, 1998, “Principles Of Cancer Patient Management” in Scientific American Medicine, vol. 3, Rubenstein and Federman, eds., ch. 12, sect. 10). Almost all chemotherapeutic agents are toxic, and chemotherapy causes significant, and often dangerous, side effects, including severe nausea, bone marrow depression, immunosuppression, etc. Additionally, even with administration of combinations of chemotherapeutic agents, many tumor cells are resistant or develop resistance to the chemotherapeutic agents. In fact, those cells resistant to the particular chemotherapeutic agents used in the treatment protocol often prove to be resistant to other drugs, even those agents that act by mechanisms different from the mechanisms of action of the drugs used in the specific treatment; this phenomenon is termed pleiotropic drug or multidrug resistance. Thus, because of drug resistance, many cancers prove refractory to standard chemotherapeutic treatment protocols.

[0024] There is a significant need for alternative cancer treatments, particularly for treatment of cancer that has proved refractory to standard cancer treatments, such as surgery, radiation therapy, chemotherapy, and hormonal therapy. A promising alternative is immunotherapy, in which cancer cells are specifically targeted by cancer antigen-specific antibodies. Major efforts have been directed at harnessing the specificity of the immune response, for example, hybridoma technology has enabled the development of tumor selective monoclonal antibodies (See Green M. C. et al., 2000 Cancer Treat Rev., 26: 269-286; Weiner L M, 1999 Semin Oncol. 26(suppl. 14):43-51), and in the past few years, the Food and Drug Administration has approved the first MAbs for cancer therapy: Rituxin (anti-CD20) for non-Hodgkin's Lymphoma and Herceptin [anti-(c-erb-2/HER-2)] for metastatic breast cancer (Suzanne A. Eccles, 2001, Breast Cancer Res., 3: 86-90). However, the potency of antibody effector function, e.g., to mediate antibody dependent cellular cytotoxicity (“ADCC”) is an obstacle to such treatment. Methods to improve the efficacy of such immunotherapy are thus needed.

[0025] 2.2.2 Inflammatory Diseases and Autoimmune Diseases

[0026] Inflammation is a process by which the body's white blood cells and chemicals protect our bodies from infection by foreign substances, such as bacteria and viruses. It is usually characterized by pain, swelling, warmth and redness of the affected area. Chemicals known as cytokines and prostaglandins control this process, and are released in an ordered and self-limiting cascade into the blood or affected tissues. This release of chemicals increases the blood flow to the area of injury or infection, and may result in the redness and warmth. Some of the chemicals cause a leak of fluid into the tissues, resulting in swelling. This protective process may stimulate nerves and cause pain. These changes, when occurring for a limited period in the relevant area, work to the benefit of the body.

[0027] In autoimmune and/or inflammatory disorders, the immune system triggers an inflammatory response when there are no foreign substances to fight and the body's normally protective immune system causes damage to its own tissues by mistakenly attacking self. There are many different autoimmune disorders which affect the body in different ways. For example, the brain is affected in individuals with multiple sclerosis, the gut is affected in individuals with Crohn's disease, and the synovium, bone and cartilage of various joints are affected in individuals with rheumatoid arthritis. As autoimmune disorders progress destruction of one or more types of body tissues, abnormal growth of an organ, or changes in organ function may result. The autoimmune disorder may affect only one organ or tissue type or may affect multiple organs and tissues. Organs and tissues commonly affected by autoimmune disorders include red blood cells, blood vessels, connective tissues, endocrine glands (e.g., the thyroid or pancreas), muscles, joints, and skin. Examples of autoimmune disorders include, but are not limited to, Hashimoto's thyroiditis, pernicious anemia, Addison's disease, type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis, Sjogren's syndrome, dermatomyositis, lupus erythematosus, multiple sclerosis, autoimmune inner ear disease myasthenia gravis, Reiter's syndrome, Graves disease, autoimmune hepatitis, familial adenomatous polyposis and ulcerative colitis.

[0028] Rheumatoid arthritis (RA) and juvenile rheumatoid arthritis are types of inflammatory arthritis. Arthritis is a general term that describes inflammation in joints. Some, but not all, types of arthritis are the result of misdirected inflammation. Besides rheumatoid arthritis, other types of arthritis associated with inflammation include the following: psoriatic arthritis, Reiter's syndrome, ankylosing spondylitis arthritis, and gouty arthritis. Rheumatoid arthritis is a type of chronic arthritis that occurs in joints on both sides of the body (such as both hands, wrists or knees). This symmetry helps distinguish rheumatoid arthritis from other types of arthritis. In addition to affecting the joints, rheumatoid arthritis may occasionally affect the skin, eyes, lungs, heart, blood or nerves.

[0029] Rheumatoid arthritis affects about 1% of the world's population and is potentially disabling. There are approximately 2.9 million incidences of rheumatoid arthritis in the United States. Two to three times more women are affected than men. The typical age that rheumatoid arthritis occurs is between 25 and 50. Juvenile rheumatoid arthritis affects 71,000 young Americans (aged eighteen and under), affecting six times as many girls as boys.

[0030] Rheumatoid arthritis is an autoimmune disorder where the body's immune system improperly identifies the synovial membranes that secrete the lubricating fluid in the joints as foreign. Inflammation results, and the cartilage and tissues in and around the joints are damaged or destroyed. In severe cases, this inflammation extends to other joint tissues and surrounding cartilage, where it may erode or destroy bone and cartilage and lead to joint deformities. The body replaces damaged tissue with scar tissue, causing the normal spaces within the joints to become narrow and the bones to fuse together. Rheumatoid arthritis creates stiffness, swelling, fatigue, anemia, weight loss, fever, and often, crippling pain. Some common symptoms of rheumatoid arthritis include joint stiffness upon awakening that lasts an hour or longer; swelling in a specific finger or wrist joints; swelling in the soft tissue around the joints; and swelling on both sides of the joint. Swelling can occur with or without pain, and can worsen progressively or remain the same for years before progressing.

[0031] The diagnosis of rheumatoid arthritis is based on a combination of factors, including: the specific location and symmetry of painful joints, the presence of joint stiffness in the morning, the presence of bumps and nodules under the skin (rheumatoid nodules), results of X-ray tests that suggest rheumatoid arthritis, and/or positive results of a blood test called the rheumatoid factor. Many, but not all, people with rheumatoid arthritis have the rheumatoid-factor antibody in their blood. The rheumatoid factor may be present in people who do not have rheumatoid arthritis. Other diseases can also cause the rheumatoid factor to be produced in the blood. That is why the diagnosis of rheumatoid arthritis is based on a combination of several factors and not just the presence of the rheumatoid factor in the blood.

[0032] The typical course of the disease is one of persistent but fluctuating joint symptoms, and after about 10 years, 90% of sufferers will show structural damage to bone and cartilage. A small percentage will have a short illness that clears up completely, and another small percentage will have very severe disease with many joint deformities, and occasionally other manifestations of the disease. The inflammatory process causes erosion or destruction of bone and cartilage in the joints. In rheumatoid arthritis, there is an autoimmune cycle of persistent antigen presentation, T-cell stimulation, cytokine secretion, synovial cell activation, and joint destruction. The disease has a major impact on both the individual and society, causing significant pain, impaired function and disability, as well as costing millions of dollars in healthcare expenses and lost wages. (See, for example, the NIH website and the NIAID website).

[0033] Currently available therapy for arthritis focuses on reducing inflammation of the joints with anti-inflammatory or immunosuppressive medications. The first line of treatment of any arthritis is usually anti-inflammatories, such as aspirin, ibuprofen and Cox-2 inhibitors such as celecoxib and rofecoxib. “Second line drugs” include gold, methotrexate and steroids. Although these are well-established treatments for arthritis, very few patients remit on these lines of treatment alone. Recent advances in the understanding of the pathogenesis of rheumatoid arthritis have led to the use of methotrexate in combination with antibodies to cytokines or recombinant soluble receptors. For example, recombinant soluble receptors for tumor necrosis factor (TNF)-α have been used in combination with methotrexate in the treatment of arthritis. However, only about 50% of the patients treated with a combination of methotrexate and anti-TNF-α agents such as recombinant soluble receptors for TNF-α show clinically significant improvement. Many patients remain refractory despite treatment. Difficult treatment issues still remain for patients with rheumatoid arthritis. Many current treatments have a high incidence of side effects or cannot completely prevent disease progression. So far, no treatment is ideal, and there is no cure. Novel therapeutics are needed that more effectively treat rheumatoid arthritis and other autoimmune disorders.

[0034] 2.2.3 Infectious Diseases

[0035] Infectious agents that cause disease fall into five groups: viruses, bacteria, fungi, protozoa, and helminths (worms). The remarkable variety of these pathogens has caused the natural selection of two crucial features of adaptive immunity. First, the advantage of being able to recognize a wide range of different pathogens has driven the development of receptors on B and T cells of equal or greater diversity. Second, the distinct habitats and life cycles of pathogens have to be countered by a range of distinct effector mechanisms. The characteristic features of each pathogen are its mode of transmission, its mechanism of replication, its pathogenesis or the means by which it causes disease, and the response it elicits.

[0036] The record of human suffering and death caused by smallpox, cholera, typhus, dysentery, malaria, etc. establishes the eminence of the infectious diseases. Despite the outstanding successes in control afforded by improved sanitation, immunization, and antimicrobial therapy, the infectious diseases continue to be a common and significant problem of modern medicine. The most common disease of mankind, the common cold, is an infectious disease, as is the feared modern disease AIDS. Some chronic neurological diseases that were thought formerly to be degenerative diseases have proven to be infectious. There is little doubt that the future will continue to reveal the infectious diseases as major medical problems.

[0037] An enormous number of human and animal diseases result from virulent and opportunistic infections from any of the above mentioned infectious agents (see Belshe (Ed.) 1984 Textbook of Human Virology, PSG Publishing, Littleton, Mass.).

[0038] One category of infectious diseases are viral infections for example. Viral diseases of a wide array of tissues, including the respiratory tract, CNS, skin, genitourinary tract, eyes, ears, immune system, gastrointestinal tract, and musculoskeletal system, affect a vast number of humans of all ages (see Table 328-2 In: Wyngaarden and Smith, 1988, Cecil Textbook of Medicine, 18^th Ed., W.B. Saunders Co., Philadelphia, pp. 1750-1753). Although considerable effort has been invested in the design of effective anti-viral therapies, viral infections continue to threaten the lives of millions of people worldwide. In general, attempts to develop anti-viral drugs have focused on several stages of viral life cycle (See e.g., Mitsuya et al., 1991, FASEB J. 5:2369-2381, discussing HIV). However, a common drawback associated with using of many current anti-viral drugs is their deleterious side effects, such as toxicity to the host or resistance by certain viral strains.

[0039] The present invention is based, in part, on the identification of mutant human IgG1 heavy chain Fc regions, with altered affinities for FcγR receptors (e.g., activating FcγRs, inhibitory FcγRs), using a yeast display system. In vivo animal modeling and clinical experiments indicate that the Fc region plays an essential role in determining the outcome of monoclonal antibody therapy. Current approaches to optimize the Fc region function (e.g., antibody-dependent cell mediated cytotoxicity (ADCC), complement dependent cytotoxicity (CDC) activity) in therapeutic monoclonal antibodies and soluble polypeptides fused to Fc regions have focused on a limited number of single amino acid changes based on structural analysis and/or computer aided designs. Alternative approaches in engineering Fc regions have focused on the glycosylation of the Fc region to optimize Fc region function. The present invention is based, in part, on selecting possible mutants for alteration in one or more Fc functional activities, such as but not limited to ADCC and CDC, from an unbiased library of Fc variants. The present invention provides methods for engineering Fc regions and identification and screening of novel Fc variants outside the expected regions identified by structural studies. Expected regions as used herein refer to those regions that based on structural and/or biochemical studies are in contact with an Fc ligand.

[0040] The present invention provides a discovery platform for the identification of Fc variants with improvement in one or more Fc effector function by combining cell based functional assays and combinatorial library construction with state of the art automation. The present invention assembles complete combinatorial libraries by saturating regions of interest within the Fc with modifications that cover all possible amino acid changes. Combinatorial libraries will be tested using a set of binding and functional assays to select mutants based on improved biological function.

[0041] Accordingly, the invention relates to molecules, preferably polypeptides, and more preferably immunoglobulins (e.g., antibodies), comprising a variant Fc region, having one or more amino acid modifications (e.g., substitutions, but also including insertions or deletions) in one or more regions, which modifications alter, e.g., increase or decrease, the affinity of the variant Fc region for an FcγR. Preferably, said one or more amino acid modification increases the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA. In a preferred embodiment, the molecules of the invention further specifically bind FcγRIIB (via the Fc region) with a lower affinity than a comparable molecule (i.e., having the same amino acid sequence as the molecule of the invention except for the one or more amino acid modifications in the Fc region) comprising the wild-type Fc region binds FcγRIIB. In some embodiments, the invention encompasses molecules with variant Fc regions, having one or more amino acid modifications, which modifications increase the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA and enhance the affinity of the variant Fc region for FcγRIIB relative to a comparable molecule with a wild type Fc region. In other embodiments, the invention encompasses molecules with variant Fc regions, having one or more amino acid modifications, which modifications increase the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA but do not alter the affinity of the variant Fc regions for FcγRIIB relative to a comparable molecule with a wild type Fc region. A preferred embodiment is a variant Fc region that has enhanced affinity for FcγRIIIA and FcγRIIA but reduced affinity for FcγRIIB relative to a comparable molecule with a wild type Fc region.

[0042] The Fc variants of the present invention may be combined with other Fc modifications, including but not limited to modifications that alter effector function. The invention encompasses combining an Fc variant of the invention with other Fc modifications to provide additive, synergistic, or novel properties in antibodies or Fc fusions. Preferably, the Fc variants of the invention enhance the phenotype of the modification with which they are combined. For example, if an Fc variant of the invention is combined with a mutant known to bind FcγRIIIA with a higher affinity than a comparable molecule comprising a wild type Fc region; the combination with a mutant of the invention results in a greater fold enhancement in FcγRIIIA affinity.

[0043] In one embodiment, the Fc variants of the present invention may be combined with other known Fc variants such as those disclosed in Duncan et al, 1988, Nature 332:563-564; Lund et al., 1991, J. Immunol 147:2657-2662; Lund et al, 1992, Mol Immunol 29:53-59; Alegre et al, 1994, Transplantation 57:1537-1543; Hutchins et al., 1995, Proc Natl. Acad Sci USA 92:11980-11984; Jefferis et al, 1995, Immunol Lett. 44:111-117; Lund et al., 1995, Faseb J 9:115-119; Jefferis et al, 1996, Immunol Lett 54:101-104; Lund et al, 1996, J Immunol 157:49634969; Ammour et al., 1999, Eur J Immunol 29:2613-2624; Idusogie et al, 2000, J Immunol 164:41784184; Reddy et al, 2000, J Immunol 164:1925-1933; Xu et al., 2000, Cell Immunol 200:16-26; Idusogie et al, 2001, J Immunol 166:2571-2575; Shields et al., 2001, J Biol Chem 276:6591-6604; Jefferis et al, 2002, Immunol Lett 82:57-65; Presta et al., 2002, Biochem Soc Trans 30:487-490); U.S. Pat. No. 5,624,821; U.S. Pat. No. 5,885,573; U.S. Pat. No. 6,194,551; PCT WO 00/42072; PCT WO 99/58572; each of which is incorporated herein by reference in its entirety. In certain embodiments, the Fc variants of the present invention may be combined with one or more of the Fc variants, i.e., amino acid modifications relative to a wild-type Fc region, presented in tables 5, 6, 7, and 8, infra.

[0044] The invention encompasses molecules that are homodimers or heterodimers of Fc regions. Heterodimers comprising Fc regions refer to molecules where the two Fc chains have the same or different sequences. In some embodiments, in the heterodimeric molecules comprising variant Fc regions, each chain has one or more different modifications from the other chain. In other embodiments, in the heterodimeric molecules comprising variant Fc regions, one chain contains the wild-type Fc region and the other chains comprises one or more modifications. Methods of engineering heterodimeric Fc containing molecules are known in the art and encompassed within the invention.

[0045] In some embodiments, the invention encompasses molecules comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild type Fc region, which variant Fc region does not bind any FcγR or binds with a reduced affinity, relative to a comparable molecule comprising the wild-type Fc region, as determined by standard assays (e.g., in vitro assays) known to one skilled in the art. In a specific embodiment, the invention encompasses molecules comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild type Fc region, which variant Fc region only binds one FcγR, wherein said FcγR is FcγIIIA. In another specific embodiment, the invention encompasses molecules comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild type Fc region, which variant Fc region only binds one FcγR, wherein said FcγR is FcγRIIA. In yet another embodiment, the invention encompasses molecules comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild type Fc region, which variant Fc region only binds one FcγR, wherein said FcγR is FcγRIIB.

[0046] The affinities and binding properties of the molecules of the invention for an FcγR are initially determined using in vitro assays (biochemical or immunological based assays) known in the art for determining Fc-FcγR interactions, i.e., specific binding of an Fc region to an FcγR including but not limited to ELISA assay, surface plasmon resonance assay, immunoprecipitation assays (See Section 5.2.1). Preferably, the binding properties of the molecules of the invention are also characterized by in vitro functional assays for determining one or more FcγR mediator effector cell functions (See Section 5.2.6). In most preferred embodiments, the molecules of the invention have similar binding properties in in vivo models (such as those described and disclosed herein) as those in in vitro based assays However, the present invention does not exclude molecules of the invention that do not exhibit the desired phenotype in in vitro based assays but do exhibit the desired phenotype in vivo.

[0047] In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable molecule comprising the wild-type Fc region binds FcγRIIIA, provided that said variant Fc region does not solely have a substitution at any one of positions 329, 331, or 332, and do not include or are not solely substitution with any one of: alanine at any of positions 256, 290, 298, 312, 333, 334, 359, 360, 326, or 430; a lysine at position 330; a threonine at position 339; a methionine at position 320; a serine at position 326; an asparagine at position 326; an aspartic acid at position 326; a glutamic acid at position 326; a glutamine at position 334; a glutamic acid at position 334; a methionine at position 334; a histidine at position 334; a valine at position 334; or a leucine at position 334; a lysine at position 335.

[0048] In another specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIA with a greater affinity than a comparable molecule comprising the wild-type Fc region binds FcγRIIA, provided that the one or more amino acid modifications do not include or are not solely substitution with an alanine at any of positions 256, 290, 326, 255, 258, 267, 272, 276, 280, 283, 285, 286, 331, 337, 268, 272, or 430; an asparagine at position 268; a glutamine at position 272; a glutamine, serine, or aspartic acid at position 286; a serine at position 290; a methionine, glutamine, glutamic acid, or arginine at position 320; a glutamic acid at position 322; a serine, glutamic acid, or aspartic acid at position 326; a lysine at position 330; a glutamine at position 335; or a methionine at position 301.

[0049] In a preferred specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said molecule has an altered affinity for an FcγR, provided that said variant Fc region does not have a substitution at positions that make a direct contact with FcγR based on crystallographic and structural analysis of Fc-FcγR interactions such as those disclosed by Sondermann et al., (2000 Nature, 406: 267-273, which is incorporated herein by reference in its entirety). Examples of positions within the Fc region that make a direct contact with FcγR are amino acids 234-239 (hinge region), amino acids 265-269 (B/C loop), amino acids 297-299 (C′/E loop), and amino acids 327-332 (F/G) loop. In some embodiments, the molecules of the invention comprising variant Fc regions comprise modification of at least one residue that does not make a direct contact with an FcγR based on structural and crystallographic analysis, e.g., is not within the Fc-FcγR binding site.

[0050] In another preferred embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said molecule binds an FcγR with an altered affinity relative to a molecule comprising a wild-type Fc region, provided that said at least one amino acid modification do not include or are not solely a substitution at any of positions 255, 256, 258, 267, 268, 269, 270, 272, 276, 278, 280, 283, 285, 286, 289, 290, 292, 293, 294, 295, 296, 298, 300, 301, 303, 305, 307, 309, 312, 320, 322, 326, 329, 330, 332, 331, 333, 334, 335, 337, 338, 339, 340, 359, 360, 373, 376, 416, 419, 430, 434, 435, 437, 438, 439. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said molecule binds an FcγR with an altered affinity relative to a molecule comprising a wild-type Fc region, provided that said variant Fc region does not include or are not solely a substitution at any of positions 255, 258, 267, 269, 270, 276, 278, 280, 283, 285, 289, 292, 293, 294, 295, 296, 300, 303, 305, 307, 309, 322, 329, 332, 331, 337, 338, 340, 373, 376, 416, 419, 434, 435, 437, 438, 439 and does not have an alanine at any of positions 256, 290, 298, 312, 333, 334, 359, 360, 326, or 430; a lysine at position 330; a threonine at position 339; a methionine at position 320; a serine at position 326; an asparagine at position 326; an aspartic acid at position 326; a glutamic acid at position 326; a glutamine at position 334; a glutamic acid at position 334; a methionine at position 334; a histidine at position 334; a valine at position 334; or a leucine at position 334; a lysine at position 335 an asparagine at position 268; a glutamine at position 272; a glutamine, serine, or aspartic acid at position 286; a serine at position 290; a methionine, glutamine, glutamic acid, or arginine at position 320; a glutamic acid at position 322; a serine, glutamic acid, or aspartic acid at position 326; a lysine at position 330; a glutamine at position 335; or a methionine at position 301.

[0051] In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region does not include or are not solely a substitution at any of positions 268, 269, 270, 272, 276, 278, 283, 285, 286, 289, 292, 293, 301, 303, 305, 307, 309, 331, 333, 334, 335, 337, 338, 340, 360, 373, 376, 416, 419, 430, 434, 435, 437, 438 or 439 and does not have a histidine, glutamine, or tyrosine at position 280; a serine, glycine, threonine or tyrosine at position 290, a leucine or isoleucine at position 300; an asparagine at position 294, a proline at position 296; a proline, asparagine, aspartic acid, or valine at position 298; a lysine at position 295. In yet another preferred embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said molecule binds an FcγR with a reduced affinity relative to a molecule comprising a wild-type Fc region provided that said variant Fc region does not have or are not solely have a substitution at any of positions 252, 254, 265, 268, 269, 270, 278, 289, 292, 293, 294, 295, 296, 298, 300, 301, 303, 322, 324, 327, 329, 333, 335, 338, 340, 373, 376, 382, 388, 389, 414, 416, 419, 434, 435, 437, 438, or 439. In yet another preferred embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said molecule binds an FcγR with an enhanced affinity relative to a molecule comprising a wild-type Fc region provided that said variant Fc region does not have or are not solely a substitution at any of positions 280, 283, 285, 286, 290, 294, 295, 298, 300, 301, 305, 307, 309, 312, 315, 331, 333, 334, 337, 340, 360, 378, 398, or 430.

[0052] In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region does not include a substitution or does not solely have a substitution at any of positions 330, 243, 247, 298, 241, 240, 244, 263, 262, 235, 269, or 328 and does not have a leucine at position 243, an asparagine at position 298, a leucine at position 241, and isoleucine or an alanine at position 240, a histidine at position 244, a valine at position 330, or an isoleucine at position 328.

[0053] In a specific embodiment, molecules of the invention comprise a variant Fc region having one or more amino acid modifications (e.g., substitutions), which modifications increase the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA by at least 2-fold, relative to a comparable molecule comprising a wild-type Fc region. In certain embodiments, molecules of the invention comprise a variant Fc region having one or more amino acid modifications (e.g., substitutions), which modifications increase the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA by greater than 2-fold, at least 4-fold, at least 5-fold, at least 6-fold, at least 8-fold, or at least 10-fold relative to a comparable molecule comprising a wild-type Fc region. In other embodiments of the invention, molecules of the invention comprising a variant Fc region specifically bind FcγRIIIA and/or FcγRIIA with at least 65%, at least 75%, at least 85%, at least 95%, at least 100%, at least 150%, at least 200% greater affinity relative to a molecule comprising a wild-type Fc region. Such measurements are preferably in vitro assays.

[0054] The invention encompasses molecules with altered affinities for the activating and/or inhibitory Fcγ receptors. In particular, the invention contemplates molecules with variant Fc regions, having one or more amino acid modifications, which modifications increase the affinity of the variant Fc region for FcγRIIB but decrease the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA, relative to a comparable molecule with a wild-type Fc region. In other embodiments, the invention encompasses molecules with variant Fc regions, having one or more amino acid modifications, which modifications decrease the affinity of the variant Fc region for FcγRIIB and also decrease the affinity of the variant Fc regions for FcγRIIIA and/or FcγRIIA relative to a comparable molecule with a wild-type Fc region. In yet other embodiments, the invention encompasses molecules with variant Fc regions, having one or more amino acid modifications, which modifications increase the affinity of the variant Fc region for FcγRIIB and also increase the affinity of the variant Fc regions for FcγRIIIA and/or FcγRIIA relative to a comparable molecule with a wild-type Fc region. In yet other embodiments, the invention encompasses molecules with variant Fc regions, which modifications decrease the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA but do not alter the affinity of the variant Fc region for FcγRIIB relative to a comparable molecule with a wild-type Fc region. In yet other embodiments, the invention encompasses molecules with variant Fc regions, which modifications increase the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA but reduce the affinity of the variant Fc region for FcγRIIB relative to a comparable molecule with a wild-type Fc region.

[0055] In a specific embodiment, the molecules of the invention comprise a variant Fc region, having one or more amino acid modifications (e.g., substitutions), which one or more modifications increase the affinity of the variant Fc region for FcγRIIIA and decrease the affinity of the variant Fc region for FcγRIIB, relative to a comparable molecule comprising a wild-type Fc region which binds FcγRIIIA and FcγRIIB with wild-type affinity. In a certain embodiment, the one or more amino acid modifications are not a substitution with alanine at any of positions 256, 298, 333, or 334.

[0056] In another specific embodiment, the molecules of the invention comprise a variant Fc region, having one or more amino acid modifications (e.g., substitutions), which one or more modifications increase the affinity of the variant Fc region for FcγRIIA and decrease the affinity of the variant Fc region for FcγRIIB, relative to a comparable molecule comprising a wild-type Fc region which binds FcγRIIA and FcγRIIB with wild-type affinity. In a certain embodiment, the one or more amino acid modifications is not a substitution with arginine at position 320.

[0057] In most preferred embodiments, the molecules of the invention with altered affinities for activating and/or inhibitory receptors having variant Fc regions, have one or more amino acid modifications, wherein said one or more amino acid modification is a substitution at position 288 with asparagine, at position 330 with serine and at position 396 with leucine (MgFc10) (See Tables 5 & 6); or a substitution at position 334 with glutamic acid, at position 359 with asparagine, and at position 366 with serine (MgFc13); or a substitution at position 316 with aspartic acid, at position 378 with valine, and at position 399 with glutamic acid (MgFc27); or a substitution at position 392 with threonine, and at position 396 with leucine (MgFc38); or a substitution at position 221 with glutamic acid, at position 270 with glutamic acid, at position 308 with alanine, at position 311 with histidine, at position 396 with leucine, and at position 402 with aspartic acid (MgFc42); or a substitution at position 240 with alanine, and at position 396 with leucine (MgFc52); or a substitution at position 410 with histidine, and at position 396 with leucine (MgFc53); or a substitution at position 243 with leucine, at position 305 with isoleucine, at position 378 with aspartic acid, at position 404 with serine, and at position 396 with leucine (MgFc54); or a substitution at position 255 with isoleucine, and at position 396 with leucine (MgFc55); or a substitution at position 370 with glutamic acid and at position 396 with leucine (MgFc59); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine (MgFc88); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine (MgFc88A); or a substitution at position 243 with leucine, at position 292 with proline, and at position 300 with leucine (MgFc155); or a substitution at position 243 with leucine, at position 292 with proline, and at position 300 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, and at position 396 with leucine; or a substitution at position 243 with leucine, and at position 292 with proline; or a substitution at position 243 with leucine; or a substitution at position 273 with phenylalanine. In a related embodiment, the variant Fc region further comprises one or more amino acid modifications disclosed in tables 5, 6, 7, and 8. infra.

[0058] The preferred method for screening and identifying molecules comprising variant Fc regions with altered FcγR affinities (e.g., enhanced FcγRIIIA affinity) is yeast surface display technology (for review see Boder and Wittrup, 2000, Methods in Enzymology, 328: 430-444, which is incorporated herein by reference in its entirety). Specifically, the yeast surface display is a genetic method whereby polypeptides comprising Fc mutants are expressed on the yeast cell wall in a form accessible for interacting with FcγR. Yeast surface display of the mutant Fc containing polypeptides of the invention may be performed in accordance with any of the techniques known to those skilled in the art or the specific methods described herein. Yeast display offers the advantage of utilizing actual binding to a desired receptor to identify variant Fc regions that have enhanced binding to that receptor.

[0059] One aspect of the invention provides a method for selecting mutant Fe fusion proteins with a desirable binding property, e.g., the ability of the mutant Fc fusion protein to bind FcγRIIIA with a greater affinity than a comparable polypeptide comprising a wild-type Fc region binds FcγRIIIA. Yeast cells displaying the mutant Fc fusion proteins can be screened and characterized by any biochemical or immunological based assays known to those skilled in the art for assessing binding interactions. In a specific embodiment, screening of mutant Fc fusion proteins is done using one or more biochemical based assays, e.g., an ELISA assay.

[0060] In preferred embodiments, screening and identifying molecules comprising variant Fc regions with altered FcγR affinities (e.g., enhanced FcγRIIIA affinity) are done using the yeast display technology as described herein in combination with one or more biochemical based assays, preferably in a high throughput manner. The one or more biochemical assays can be any assay known in the art for identifying Fc-FcγR interaction, i.e., specific binding of an Fc region to an FcγR, including, but not limited to, an ELISA assay, surface plasmon resonance assays, immunoprecipitation assay, affinity chromatography, and equilibrium dialysis. In some embodiments, screening and identifying molecules comprising variant Fc regions with altered FcγR affinities (e.g., enhanced FcγRIIIA affinity) are done using the yeast display technology as described herein in combination with one or more functional based assays, preferably in a high throughput manner. The functional based assays can be any assay known in the art for characterizing one or more FcγR mediated effector cell function such as those described herein in Section 5.2.6. Non-limiting examples of effector cell functions that can be used in accordance with the methods of the invention, include but are not limited to, antibody-dependent cell mediated cytotoxicity (ADCC), antibody-dependent phagocytosis, phagocytosis, opsonization, opsonophagocytosis, cell binding, rosetting, C1q binding, and complement dependent cell mediated cytotoxicity. In some embodiments, screening and identifying molecules comprising variant Fc regions with altered FcγR affinities (e.g., enhanced FcγRIIIA affinity) are done using the yeast display technology as described herein in combination with one or more biochemical based assays in combination or in parallel with one or more functional based assays, preferably in a high throughput manner.

[0061] A preferred method for measuring the FcγR-Fc interaction in accordance with the invention is an assay developed by the inventors, which allows detection and quantitation of the interaction, despite the inherently weak affinity of the receptor for its ligand, e.g., in the micromolar range for FcγRIIB and FcγRIIIA. The method involves the formation of an FcγR complex (e.g., FcγRIIIA, FcγRIIB) that has an improved avidity for an Fc region, relative to an uncomplexed FcγR. In a specific embodiment, the invention encompasses a method for producing a tetrameric FcγR complex, wherein said tetrameric complex has an enhanced affinity for an Fc region, relative to the affinity of a monomeric FcγR for the Fc region, said method comprising: (i) producing a fusion protein, such that a 15 amino acid AVITAG sequence operably linked to the soluble region of FcγR; (ii) biotinylating the protein produced using an E. coli BirA enzyme; (iii) mixing the biotinylated protein produced with streptavidin-phycoerythrin in an appropriate molar ratio, such that a tetrameric FcγR complex is formed.

[0062] In a preferred embodiment of the invention, polypeptides comprising Fc regions bind the tetrameric FcγR complexes, formed according to the methods of the invention, with at least an 8-fold higher affinity than they bind the monomeric uncomplexed FcγR. The binding of polypeptides comprising Fc regions to the tetrameric FcγR complexes may be determined using standard techniques known to those skilled in the art, such as for example, fluorescence activated cell sorting (FACS), radioimmunoassays, ELISA assays, etc.

[0063] The invention encompasses the use of the immune complexes formed according to the methods described above for determining the functionality of molecules comprising an Fc region in cell-based or cell-free assays.

[0064] In a specific embodiment, the invention provides modified immunoglobulins comprising a variant Fc region with an enhanced affinity for FcγRIIIA and/or FcγRIIA. Such immunoglobulins include IgG molecules that naturally contain FcγR binding regions (e.g., FcγRIIIA and/or FcγRIIB binding regions), or immunoglobulin derivatives that have been engineered to contain an FcγR binding region (e.g., FcγRIIIA and/or FcγRIIB binding regions). The modified immunoglobulins of the invention include any immunoglobulin molecule that binds, preferably, immunospecifically, i.e., competes off non-specific binding as determined by immunoassays well known in the art for assaying specific antigen-antibody binding, an antigen and contains an FcγR binding region (e.g., a FcγRIIIA and/or FcγRIIB binding region). Such antibodies include, but are not limited to, polyclonal, monoclonal, bi-specific, multi-specific, human, humanized, chimeric antibodies, single chain antibodies, Fab fragments, F(ab′)₂ fragments, disulfide-linked Fvs, and fragments containing either a VL or VH domain or even a complementary determining region (CDR) that specifically binds an antigen, in certain cases, engineered to contain or fused to an FcγR binding region.

[0065] In certain embodiment, the invention encompasses immunoglobulins comprising a variant Fc region with an enhanced affinity for FcγRIIIA and/or FcγRIIA such that the immunoglobulin has an enhanced effector function, e.g., antibody dependent cell mediated cytotoxicity. The effector function of the molecules of the invention can be assayed using any assay described herein or known to those skilled in the art. In some embodiments, immunoglobulins comprising a variant Fc region with an enhanced affinity for FcγRIIIA and/or FcγRIIA have an enhanced ADCC activity relative to wild-type by at least 2-fold, at least 4-fold, at least 8-fold, at least 10-fold, at least 50-fold, or at least 100-fold.

[0066] The invention encompasses engineering human or humanized therapeutic antibodies (e.g., tumor specific monoclonal antibodies) in the Fc region by modification (e.g., substitution, insertion, deletion) of one or more amino acid residues, which modifications modulate the affinity of the therapeutic antibody for an FcγR activating receptor and/or an FcγR inhibitory receptor. In one embodiment, the invention relates to engineering human or humanized therapeutic antibodies (e.g., tumor specific monoclonal antibodies) in the Fc region by modification of one or more amino acid residues, which modifications increase the affinity of the Fc region for FcγRIIIA and/or FcγRIIA. In another embodiment, the invention relates to engineering human or humanized therapeutic antibodies (e.g., tumor specific monoclonal antibodies) in the Fc region by modification of one or more amino acid residues, which modification increases the affinity of the Fc region for FcγRIIIA and/or FcγRIIA and further decreases the affinity of the Fc region for FcγRIIB. The engineered therapeutic antibodies may further have an enhanced effector function, e.g., enhanced ADCC activity, phagocytosis activity, etc., as determined by standard assays known to those skilled in the art.

[0067] In a specific embodiment, the invention encompasses engineering a humanized monoclonal antibody specific for Her2/neu protooncogene (e.g., Ab4D5 humanized antibody as disclosed in Carter et al., 1992, Proc. Natl. Acad. Sci. USA 89:4285-9) by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fc region for FcγRIIIA and/or FcγRIIA. In another specific embodiment, modification of the humanized Her2/neu monoclonal antibody may also further decrease the affinity of the Fc region for FcγRIIB. In yet another specific embodiment, the engineered humanized monoclonal antibodies specific for Her2/neu may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein.

[0068] In another specific embodiment, the invention encompasses engineering an anti-CD20 antibody by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fc region for FcγRIIIA and/or FcγRIIA. In a related embodiment, the anti-CD20 antibody is mouse human chimeric anti-CD20 monoclonal antibody, 2H7 Further nonlimiting examples of anti-CD20 antibodies that can be used in the methods of the invention are disclosed in U.S. patent application Ser. No. 11/271,140, filed Nov. 10, 2005, hereby incorporated by reference in its entirety. In another specific embodiment, modification of the anti-CD20 monoclonal antibody, 2H7 may also further decrease the affinity of the Fc region for FcγRIIB. In yet another specific embodiment, the engineered anti-CD20 monoclonal antibody, 2H7 may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein.

[0069] In another specific embodiment, the invention encompasses engineering an anti-FcγRIIB antibody, in particular an anti-FcγRIIB antibody that specifically binds human FcγRIIB, more particularly native human FcγRIIB, by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fc region for FcγRIIIA and/or FcγRIIA. Non-limiting examples of representative anti-FcγRIIB antibodies are disclosed in U.S. Provisional Application No. 60/403,266 filed on Aug. 12, 2002; U.S. application Ser. No. 10/643,857 filed on Aug. 14, 2003; and U.S Patent Application Publication Nos.: 2004-0185045; 2005-0260213; and 2006-0013810, all of which are hereby incorporated by reference in their entireties. Examples of anti-FcγRIIB antibodies that may be engineered in accordance with the methods of the invention are the monoclonal antibodies produced by clone 2B6, 3H7, 8B5.4.3, 1D5, 2E1, 2H9, 2D11 and 1F2 having ATCC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively (deposited at ATCC, 10801 University Boulevard, Manassas, Va. 02209-2011, all of which are incorporated herein by reference), or chimeric, humanized or other engineered versions thereof.

[0070] In a specific embodiment, the invention encompasses engineering a humanized antibody comprising the heavy chain variable domain and/or light chain variable domain of 2B6, 3H7 or 8B5.3.4. In another specific embodiment, the invention encompasses engineering a humanized antibody comprising the CDRs of 2B6, 3H7 or 8B5.3.4. In a specific embodiment, the invention encompasses engineering a humanized antibody comprising the heavy chain variable domain having the amino acid sequence of SEQ ID NO: 1, SEQ ID NO:2 or SEQ ID NO:3 and the light chain variable domain having the amino acid sequence of SEQ ID NO: 4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7 or SEQ ID NO: 8. In a specific embodiment, the invention encompasses engineering a humanized antibody comprising the heavy chain variable domain having the amino acid sequence of SEQ ID NO:9 and the light chain variable domain having the amino acid sequence of SEQ ID NO:10.

[0071] In another specific embodiment, modification of the anti-FcγRIIB antibody may also further decrease the affinity of the Fc region for FcγRIIB. In yet another specific embodiment, the engineered anti-FcγRIIB antibody may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein. In a specific embodiment, the anti-FcγRIIB monoclonal antibody comprises a modification at position 334 with glutamic acid, at position 359 with asparagine, and at position 366 with serine (MgFc13); or a substitution at position 316 with aspartic acid, at position 378 with valine, and at position 399 with glutamic acid (MgFc27); or a substitution at position 243 with isoleucine, at position 379 with leucine, and at position 420 with valine (MgFc29); or a substitution at position 392 with threonine and at position 396 with leucine (MgFc38); or a substitution at position 221 with glutamic acid, at position 270 with glutamic acid, at position 308 with alanine, at position 311 with histidine, at position 396 with leucine, and at position 402 with aspartic (MgFc42); or a substitution at position 410 with histidine, and at position 396 with leucine (MgFc53); or a substitution at position 243 with leucine, at position 305 with isoleucine, at position 378 with aspartic acid, at position 404 with serine, and at position 396 with leucine (MgFc54); or a substitution at position 255 with isoleucine, and at position 396 with leucine (MgFc55); or a substitution at position 370 with glutamic acid, and at position 396 with leucine (MgFc59); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine (MgFc88); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine (MgFc88A); or a substitution at position 234 with leucine, at position 292 with proline, and at position 300 with leucine (MgFc155); or a substitution at position 243 with leucine, at position 292 with proline, and at position 300 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, and at position 396 with leucine; or a substitution at position 243 with leucine, and at position 292 with proline; or a substitution at position 243 with leucine; or a substitution at position 273 with phenylalanine. In a related embodiment, the variant Fc region further comprises one or more amino acid modifications disclosed in tables 5, 6, 7, and 8, infra.

[0072] The present invention also includes polynucleotides that encode a molecule of the invention, including polypeptides and antibodies, identified by the methods of the invention. The polynucleotides encoding the molecules of the invention may be obtained, and the nucleotide sequence of the polynucleotides determined, by any method known in the art. The invention relates to an isolated nucleic acid encoding a molecule of the invention. The invention also provides a vector comprising said nucleic acid. The invention further provides host cells containing the vectors or polynucleotides of the invention.

[0073] The invention further provides methods for the production of the molecules of the invention. The molecules of the invention, including polypeptides and antibodies, can be produced by any method known to those skilled in the art, in particular, by recombinant expression. In a specific embodiment, the invention relates to a method for recombinantly producing a molecule of the invention, said method comprising: (i) culturing in a medium a host cell comprising a nucleic acid encoding said molecule, under conditions suitable for the expression of said molecule; and (ii) recovery of said molecule from said medium.

[0074] The molecules identified in accordance with the methods of the invention are useful in preventing, treating, or ameliorating one or more symptoms associated with a disease, disorder, or infection. The molecules of the invention are particularly useful for the treatment or prevention of a disease or disorder where an enhanced efficacy of effector cell function (e.g., ADCC) mediated by FcγR is desired, e.g., cancer, infectious disease, and in enhancing the therapeutic efficacy of therapeutic antibodies the effect of which is mediated by ADCC.

[0075] In one embodiment, the invention encompasses a method of treating cancer in a patient having a cancer characterized by a cancer antigen, said method comprising administering a therapeutically effective amount of a therapeutic antibody that binds the cancer antigen, which has been engineered in accordance with the methods of the invention. In a specific embodiment, the invention encompasses a method for treating cancer in a patient having a cancer characterized by a cancer antigen, said method comprising administering a therapeutically effective amount of a therapeutic antibody that specifically binds said cancer antigen, said therapeutic antibody comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said therapeutic antibody specifically binds FcγRIIIA with a greater affinity than the therapeutic antibody comprising the wild-type Fc region binds FcγRIIIA, provided that said variant Fc region does not have a substitution at positions 329, 331, or 332, and does not have an alanine at any of positions 256, 290, 298, 312, 333, 334, 359, 360, or 430; a lysine at position 330; a threonine at position 339; a methionine at position 320; a serine at position 326; an asparagine at position 326; an aspartic acid at position 326; a glutamic acid at position 326; a glutamine at position 334; a glutamic acid at position 334; a methionine at position 334; a histidine at position 334; a valine at position 334; or a leucine at position 334. In another specific embodiment, the invention encompasses a method for treating cancer in a patient having a cancer characterized by a cancer antigen, said method comprising administering a therapeutically effective amount of a therapeutic antibody that specifically binds a cancer antigen, said therapeutic antibody comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region such that said therapeutic antibody specifically binds FcγRIIIA with a greater affinity than a therapeutic antibody comprising the wild-type Fc region binds FcγRIIIA, and said therapeutic antibody further specifically binds FcγRIIB with a lower affinity than a therapeutic antibody comprising the wild-type Fc region binds FcγRIIB, provided that said variant Fc region does not have an alanine at any of positions 256, 298, 333, or 334. The invention encompasses a method for treating cancer in a patient characterized by a cancer antigen, said method comprising administering a therapeutically effective amount of a therapeutic antibody that specifically binds said cancer antigen and said therapeutic antibody comprises a variant Fc region so that the antibody has an enhanced ADCC activity.

[0076] The invention encompasses a method of treating an autoimmune disorder and/or inflammatory disorder in a patient in need thereof, said method comprising administering to said patient a therapeutically effective amount of a molecule comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild type Fc region, such that said molecule specifically binds FcγRIIB with a greater affinity than a comparable molecule comprising the wild type Fc region, and said molecule further specifically binds FcγRIIIA with a lower affinity than a comparable molecule comprising the wild type Fc region, and said molecule binds an immune complex (e.g., an antigen/antibody complex). The invention encompasses a method of treating an autoimmune disorder and/or inflammatory disorder further comprising administering one or more additional prophylactic or therapeutic agents, e.g., immunomodulatory agents, anti-inflammatory agents, used for the treatment and/or prevention of such diseases.

[0077] The invention also encompasses methods for treating or preventing an infectious disease in a subject comprising administering a therapeutically or prophylactically effective amount of one or more molecules of the invention that bind an infectious agent or cellular receptor therefor. Infectious diseases that can be treated or prevented by the molecules of the invention are caused by infectious agents including but not limited to viruses, bacteria, fungi, protozae, and viruses.

[0078] According to one aspect of the invention, molecules of the invention comprising variant Fc regions have an enhanced antibody effector function towards an infectious agent, e.g., a pathogenic protein, relative to a comparable molecule comprising a wild-type Fc region. In a specific embodiment, molecules of the invention enhance the efficacy of treatment of an infectious disease by enhancing phagocytosis and/or opsonization of the infectious agent causing the infectious disease. In another specific embodiment, molecules of the invention enhance the efficacy of treatment of an infectious disease by enhancing ADCC of infected cells causing the infectious disease.

[0079] In some embodiments, the molecules of the invention may be administered in combination with a therapeutically or prophylactically effective amount of one or additional therapeutic agents known to those skilled in the art for the treatment and/or prevention of an infectious disease. The invention contemplates the use of the molecules of the invention in combination with antibiotics known to those skilled in the art for the treatment and or prevention of an infectious disease.

[0080] The invention provides pharmaceutical compositions comprising a molecule of the invention, e.g., a polypeptide comprising a variant Fc region, an immunoglobulin comprising a variant Fc region, a therapeutic antibody engineered in accordance with the invention, and a pharmaceutically acceptable carrier. The invention additionally provides pharmaceutical compositions further comprising one or more additional therapeutic agents, including but not limited to anti-cancer agents, anti-inflammatory agents, immunomodulatory agents.

[0081] 3.1 Definitions

[0082] As used herein, the term “Fc region” is used to define a C-terminal region of an IgG heavy chain. Although the boundaries may vary slightly, the human IgG heavy chain Fc region is defined to stretch from Cys226 to the carboxy terminus. The Fc region of an IgG comprises two constant domains, CH2 and CH3. The CH2 domain of a human IgG Fc region (also referred to as “Cγ2” domain) usually extends from amino acid 231 to amino acid 338. The CH3 domain of a human IgG Fc region usually extends from amino acids 342 to 447. The CH2 domain is unique in that it is not closely paired with another domain. Rather, two N-linked branched carbohydrate chains are interposed between the two CH2 domains of an intact native IgG.

[0083] Throughout the present specification, the numbering of the residues in an IgG heavy chain is that of the EU index as in Kabat et al., Sequences of Proteins of Immunological Interest, 5^th Ed. Public Health Service, NH1, MD (1991), expressly incorporated herein by references. The “EU index as in Kabat” refers to the numbering of the human IgG1 EU antibody.

[0084] The “hinge region” is generally defined as stretching from Glu216 to Pro230 of human IgG1. Hinge regions of other IgG isotypes may be aligned with the IgG1 sequence by placing the first and last cysteine residues forming inter-heavy chain S—S bonds in the same positions.

[0085] As used herein, the terms “antibody” and “antibodies” refer to monoclonal antibodies, multispecific antibodies, human antibodies, humanized antibodies, synthetic antibodies, chimeric antibodies, polyclonal antibodies, camelized antibodies, single-chain Fvs (scFv), single chain antibodies, Fab fragments, F(ab′) fragments, disulfide-linked bispecific Fvs (sdFv), intrabodies, and anti-idiotypic (anti-Id) antibodies (including, e.g., anti-Id and anti-anti-Id antibodies to antibodies of the invention), and epitope-binding fragments of any of the above. In particular, antibodies include immunoglobulin molecules and immunologically active fragments of immunoglobulin molecules, i.e., molecules that contain an antigen binding site. Immunoglobulin molecules can be of any type (e.g., IgG, IgE, IgM, IgD, IgA and IgY), class (e.g., IgG₁, IgG2, IgG3, IgG4, IgA₁ and IgA₂) or subclass.

[0086] As used herein, the term “derivative” in the context of polypeptides or proteins refers to a polypeptide or protein that comprises an amino acid sequence which has been altered by the introduction of amino acid residue substitutions, deletions or additions. The term “derivative” as used herein also refers to a polypeptide or protein which has been modified, i.e., by the covalent attachment of any type of molecule to the polypeptide or protein. For example, but not by way of limitation, an antibody may be modified, e.g., by glycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc. A derivative polypeptide or protein may be produced by chemical modifications using techniques known to those of skill in the art, including, but not limited to specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. Further, a derivative polypeptide or protein derivative possesses a similar or identical function as the polypeptide or protein from which it was derived.

[0087] As used herein, the term “derivative” in the context of a non-proteinaceous derivative refers to a second organic or inorganic molecule that is formed based upon the structure of a first organic or inorganic molecule. A derivative of an organic molecule includes, but is not limited to, a molecule modified, e.g., by the addition or deletion of a hydroxyl, methyl, ethyl, carboxyl or amine group. An organic molecule may also be esterified, alkylated and/or phosphorylated.

[0088] As used herein, the terms “disorder” and “disease” are used interchangeably to refer to a condition in a subject. In particular, the term “autoimmune disease” is used interchangeably with the term “autoimmune disorder” to refer to a condition in a subject characterized by cellular, tissue and/or organ injury caused by an immunologic reaction of the subject to its own cells, tissues and/or organs. The term “inflammatory disease” is used interchangeably with the term “inflammatory disorder” to refer to a condition in a subject characterized by inflammation, preferably chronic inflammation. Autoimmune disorders may or may not be associated with inflammation. Moreover, inflammation may or may not be caused by an autoimmune disorder. Thus, certain disorders may be characterized as both autoimmune and inflammatory disorders.

[0089] As used herein, the term “cancer” refers to a neoplasm or tumor resulting from abnormal uncontrolled growth of cells. As used herein, cancer explicitly includes, leukemias and lymphomas. In some embodiments, cancer refers to a benign tumor, which has remained localized. In other embodiments, cancer refers to a malignant tumor, which has invaded and destroyed neighboring body structures and spread to distant sites. In some embodiments, the cancer is associated with a specific cancer antigen.

[0090] As used herein, the term “immunomodulatory agent” and variations thereof refer to an agent that modulates a host's immune system. In certain embodiments, an immunomodulatory agent is an immunosuppressant agent. In certain other embodiments, an immunomodulatory agent is an immunostimulatory agent. Immunomodatory agents include, but are not limited to, small molecules, peptides, polypeptides, fusion proteins, antibodies, inorganic molecules, mimetic agents, and organic molecules.

[0091] As used herein, the term “epitope” refers to a fragment of a polypeptide or protein or a non-protein molecule having antigenic or immunogenic activity in an animal, preferably in a mammal, and most preferably in a human. An epitope having immunogenic activity is a fragment of a polypeptide or protein that elicits an antibody response in an animal. An epitope having antigenic activity is a fragment of a polypeptide or protein to which an antibody immunospecifically binds as determined by any method well-known to one of skill in the art, for example by immunoassays. Antigenic epitopes need not necessarily be immunogenic.

[0092] As used herein, the term “fragment” refers to a peptide or polypeptide comprising an amino acid sequence of at least 5 contiguous amino acid residues, at least 10 contiguous amino acid residues, at least 15 contiguous amino acid residues, at least 20 contiguous amino acid residues, at least 25 contiguous amino acid residues, at least 40 contiguous amino acid residues, at least 50 contiguous amino acid residues, at least 60 contiguous amino residues, at least 70 contiguous amino acid residues, at least contiguous 80 amino acid residues, at least contiguous 90 amino acid residues, at least contiguous 100 amino acid residues, at least contiguous 125 amino acid residues, at least 150 contiguous amino acid residues, at least contiguous 175 amino acid residues, at least contiguous 200 amino acid residues, or at least contiguous 250 amino acid residues of the amino acid sequence of another polypeptide. In a specific embodiment, a fragment of a polypeptide retains at least one function of the polypeptide.

[0093] As used herein, the terms “nucleic acids” and “nucleotide sequences” include DNA molecules (e.g., cDNA or genomic DNA), RNA molecules (e.g., mRNA), combinations of DNA and RNA molecules or hybrid DNA/RNA molecules, and analogs of DNA or RNA molecules. Such analogs can be generated using, for example, nucleotide analogs, which include, but are not limited to, inosine or tritylated bases. Such analogs can also comprise DNA or RNA molecules comprising modified backbones that lend beneficial attributes to the molecules such as, for example, nuclease resistance or an increased ability to cross cellular membranes. The nucleic acids or nucleotide sequences can be single-stranded, double-stranded, may contain both single-stranded and double-stranded portions, and may contain triple-stranded portions, but preferably is double-stranded DNA.

[0094] As used herein, a “therapeutically effective amount” refers to that amount of the therapeutic agent sufficient to treat or manage a disease or disorder. A therapeutically effective amount may refer to the amount of therapeutic agent sufficient to delay or minimize the onset of disease, e.g., delay or minimize the spread of cancer. A therapeutically effective amount may also refer to the amount of the therapeutic agent that provides a therapeutic benefit in the treatment or management of a disease. Further, a therapeutically effective amount with respect to a therapeutic agent of the invention means the amount of therapeutic agent alone, or in combination with other therapies, that provides a therapeutic benefit in the treatment or management of a disease.

[0095] As used herein, the terms “prophylactic agent” and “prophylactic agents” refer to any agent(s) which can be used in the prevention of a disorder, or prevention of recurrence or spread of a disorder. A prophylactically effective amount may refer to the amount of prophylactic agent sufficient to prevent the recurrence or spread of hyperproliferative disease, particularly cancer, or the occurrence of such in a patient, including but not limited to those predisposed to hyperproliferative disease, for example those genetically predisposed to cancer or previously exposed to carcinogens. A prophylactically effective amount may also refer to the amount of the prophylactic agent that provides a prophylactic benefit in the prevention of disease. Further, a prophylactically effective amount with respect to a prophylactic agent of the invention means that amount of prophylactic agent alone, or in combination with other agents, that provides a prophylactic benefit in the prevention of disease.

[0096] As used herein, the terms “prevent”, “preventing” and “prevention” refer to the prevention of the recurrence or onset of one or more symptoms of a disorder in a subject as result of the administration of a prophylactic or therapeutic agent.

[0097] As used herein, the term “in combination” refers to the use of more than one prophylactic and/or therapeutic agents. The use of the term “in combination” does not restrict the order in which prophylactic and/or therapeutic agents are administered to a subject with a disorder. A first prophylactic or therapeutic agent can be administered prior to (e.g., 5 minutes, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48 hours, 72 hours, 96 hours, 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 8 weeks, or 12 weeks before), concomitantly with, or subsequent to (e.g., 5 minutes, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48 hours, 72 hours, 96 hours, 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 8 weeks, or 12 weeks after) the administration of a second prophylactic or therapeutic agent to a subject with a disorder.

[0098] “Effector function” as used herein is meant a biochemical event that results from the interaction of an antibody Fc region with an Fc receptor or ligand. Effector functions include but are not limited to antibody dependent cell mediated cytotoxicity (ADCC), antibody dependent cell mediated phagocytosis (ADCP), and complement dependent cytotoxicity (CDC). Effector functions include both those that operate after the binding of an antigen and those that operate independent of antigen binding.

[0099] “Effector cell” as used herein is meant a cell of the immune system that expresses one or more Fc receptors and mediates one or more effector functions. Effector cells include but are not limited to monocytes, macrophages, neutrophils, dendritic cells, eosinophils, mast cells, platelets, B cells, large granular lymphocytes, Langerhans' cells, natural killer (NK) cells, and may be from any organism including but not limited to humans, mice, rats, rabbits, and monkeys.

[0100] “Fc ligand” as used herein is meant a molecule, preferably a polypeptide, from any organism that binds to the Fc region of an antibody to form an Fc-ligand complex. Fc ligands include but are not limited to FcγRs, FcγRs, FcγRs, FcRn, C1q, C3, staphylococcal protein A, streptococcal protein G, and viral FcγR. Fc ligands may include undiscovered molecules that bind Fc.

[0101] FIG. 1 Schematic of Sequence of 8B5.3.4 Variable Light Chain Domain

[0102] Depiction of the 8B5.3.4 VL nucleotide and amino acid sequence (SEQ ID NOS:11 and 10, respectively).

[0103] FIG. 2 Schematic of Sequence of 8B5.3.4 Variable Heavy Chain Domain

[0104] Depiction of the of the 8B5.3.4 VH nucleotide and amino acid sequence (SEQ ID NOS:12 and 9, respectively).

[0105] FIG. 3 SDS-PAGE Analysis of Recombinant Soluble FcγR

[0106] The purity of recombinant soluble FcγR proteins was assessed by 10% polyacrylamide gel electrophoresis. The gels were stained with Coomassie blue. Lane 1: purified recombinant soluble FcγRIIIA; Lane 2: molecular weight marker; Lane 3: molecular weight marker; Lane 4: purified recombinant soluble FcγRIIB. The dashes refer to the molecular weight of the markers, from top to bottom, they correspond to a molecular weight of 98, 50, 36, and 22 KDa respectively.

[0107] FIG. 4 Elisa Assay of Recombinant Soluble FcγR

[0108] The direct binding of purified recombinant soluble FcγRIIIA to aggregated and monomeric IgG was determined using an ELISA assay. Binding of (▴) aggregated IgG with 3G8; (♦) Biotinylated IgG; (▪) aggregated IgG; (X) aggregated IgG with mouse IgG1.

[0109] FIGS. 5 A and B Characterization of FcγRIIIA Tetrameric Complex Using an Elisa Assay

[0110] A. Soluble tetrameric FcγRIIIA complex binds soluble monomeric human IgG specifically. Binding of soluble tetrameric FcγRIIIA to human IgG is blocked by 3G8 (♦), a mouse anti-FcγIIIA monoclonal antibody; the 4-4-20 monoclonal antibody harboring the D265A mutation was not able to block the binding of soluble tetrameric FcγRIIIA to aggregated human IgG (Δ).

[0111] B. Binding of soluble tetrameric FcγRIIIA complex to soluble monomeric human IgG (▪) is compared to the binding of monomeric soluble FcγRIIIA to soluble monomeric human IgG (♦).

[0112] FIGS. 6 A and B Characterization of FcγRIIIA Tetrameric Complex Using a Magnetic Bead Assay

[0113] A. FcγRIIIA Complex: two FcγRIIIA (filled shape) are joined by a monoclonal antibody DJ130c (1^st Ab); the anti-mouse F(ab)₂ is conjugated to PE (circle).

[0114] B. FACS analysis of FcγRIIIA bound to Fc coated beads: (a) beads alone; (b) complex without FcγRIIIA; (c) complex with FcγRIIIA; (d) complex with FcγRIIIA and LNK16.

[0115] FIG. 7 Schematic Presentation of Fc Containing Constructs

[0116] A schematic diagram of the IgG1 Fc domains cloned into pYD1 is presented. The open box represents the hinge-CH2-CH3 domains; parallel vertical lines represent the CH1 domain. In the case of the GIF206 and 227 constructs; the N-terminal amino acids are shown. The underlined residues correspond to the hinge region; the * represents the Xpress epitope tag; hatched boxes represent the Gly4-Ser linker, and the stippled boxes represent the Aga2p gene.

[0117] FIGS. 8A-H FACS Analysis of the Fc Fusion Proteins on the Yeast Cell Wall

[0118] Cells were incubated with either a PE-conjugated polyclonal goat anti-human Fc antibody (FIGS. 8A-D) or with HP6017 (Sigma), a mouse anti-human IgG1 Fc (CH3) specific monoclonal antibody (FIGS. 8E-H). A and E represent vector alone; Panels B and F represent the CH1-CH3 construct; Panels C and G represent the GIF227; and Panels D and H represent the GIF 206 construct.

[0119] FIGS. 9A-C Binding of Soluble Tetrameric FcγRIIIA to the Surface Displayed Fc Fusion Proteins

[0120] Cells containing pYD1-CH1 (A); pYD-CH1-D265A (B); and pYD vector (C) were grown under conditions to express Aga2p fusion proteins on the cell surface. Cells were incubated with FcγRIIIA at 0.15 mM, 7.5 mM, and 7.5 mM, respectively, and analyzed by FACS.

[0121] FIG. 10 Characterization of the Binding of Soluble Tetrameric FcγRIIIA to the Surface Displayed Fc Fusion Proteins

[0122] Binding of FcγRIIIA tetrameric complex to Fc fusion proteins on the yeast cell surface was analyzed. PE-conjugated FcγRIIIA tetrameric complexes were pre-incubated with different concentrations of 3G8 (♦), LNK (▴) or an irrelevant isotype control (▪), and subsequently incubated with the yeast cells. Cells were analyzed by FACS for PE fluorescence. The percent cells that bound the FcγRIIIA tetrameric complex were plotted on the y-axis.

[0123] FIG. 11 Example of Sort Gate for Selecting Fc Mutants with Increased Binding to FcγRIIIA

[0124] Cells were stained with PE-conjugated FcγRIIIA tetrameric complexes (y-axis) and anti-Fc-FITC conjugated antibody (x-axis). Boxed area represents sort gate set to select ˜1.0% of the cell population.

[0125] FIGS. 12A-N FACS Analysis of Some of the Fc Mutants Identified Having an Increased Affinity for FcγRIIIA Tetrameric Complexes

[0126] Individual clones harboring the pYD-CH1 plasmid containing independent Fc mutations were amplified in selective media containing glucose, induced for Fc expression in selective media containing galactose, and subsequently analyzed by FACs. FIGS. 12A and B represent cells harboring wild-type Fc; FIGS. 12C and D represent mutant # 5; FIGS. 12E and F represent mutant # 20; FIGS. 12G and H represent mutant # 21; FIGS. 12 I and J represent mutant # 24; FIGS. 12K and L represent mutant # 25; FIGS. 12M and N represent mutant # 27. Cells were stained with FcγRIIIA tetrameric complex (FIGS. 12 A, C, E, G, I, K, and M) or FcγRIIB tetrameric complex (FIGS. 12 B, D, F, H, J, L, and N).

[0127] FIGS. 13 A-B Characterization of Fc Mutants in the 4-4-20 Monoclonal Antibody by ELISA

[0128] Fc domains from the pYD-CH1 plasmids were cloned into the heavy chain of the chimeric 4-4-20 monoclonal antibody. The 4-4-20 monoclonal antibody was expressed in 293 cells and supernatants were collected. ELISA plates were coated with fluoresceine conjugated BSA to capture the chimeric 4-4-20 mutant antibodies. FcγRIIIA (A) and FcγRIIB (B) receptors were then coated onto the ELISA plates to which the 4-4-20 monoclonal antibodies had been absorbed in order to determine the relative affinities of the variant receptors to the Fc domains. Mutants # 15 and # 29 were non-binding isolates included as controls.

[0129] FIG. 14 ADCC Activity of Mutants in the 4-4-20 Monoclonal Antibody

[0130] 4-4-20 antibodies containing mutant Fc regions were assessed for their ADCC activity, and compared to the ADCC activity of a wild type 4-4-20 antibody. The mutants analyzed are as follows: MGFc-10 (K288N, A330S, P396L), MGFc-26 (D265A), MGFc-27 (G316D, A378V, D399E), MGFc28 (N3151, A379M, D399E), MGFc29 (F2431, V379L, G420V), MGFc30 (F275V), MGFc-31 (P247L, N421K), MGFc-32 (D280E, S354F, A431D, L4411), MGFc-33 (K317N, F423 deleted), MGFc-34 (F241L, E258G), MGFc-35 (R255Q, K326E), MGFc-36 (K218R, G281D, G385R)

[0131] FIGS. 15 A and B ADCC Activity of Mutants in the HER2/NEU Humanized Monoclonal Antibody

[0132] A. Humanized HER2/neu monoclonal antibodies containing mutant Fc regions were assessed for their ADCC activity and compared to the ADCC activity of a wild type Her2/neu antibody. The mutants analyzed are as follows: MGFc-5 (V379M), MGFc-9 (F2431, V379L), MGFc-10 (K288N, A330S, P396L), MGFc-13 (K334E, T359N, T366S), MGFc-27 (G316D, A378V, D399E).

[0133] B. ADCC activity of additional mutants in the context of the humanized Her2/neu monoclonal antibody MGFc-37 (K248M), MGFc-39 (E293V Q295E, A327T), MGFc-38 (K392T, P396L), MGFc-41 (H268N, P396L), MGFc-23 (K334E, R292L), MGFc-44, MGFc-45. Two independent clones were teseted for each mutant.

[0134] FIG. 16 Capture of CH 4-4-20 Antibody on BSA-FITC Surface

[0135] 6 μL of antibody at a concentration of approximately 20 μg/mL was injected at 5 μL/min over a BSA-fluoroscein isothiocyanate (FITC) surface. BIAcore sensogram of the binding of ch 4-4-20 antibodies with mutant Fc regions on the surface of the BSA-FITC immobilized sensor ship is shown. The marker was set on wild-type captured antibody response.

[0136] FIG. 17 Sensogram of Real Time Binding of FcγRIIIA to CH 4-4-Antibodies Carrying Variant Fc Regions

[0137] Binding of FcγRIIIA to ch-4-4-20 antibodies carrying variant Fc regions was analyzed at 200 nM concentration. Responses were normalized at the level of ch-4-4-20 antibody obtained for wild-type.

[0138] Mutants used were as follows: Mut 6 (S219V), Mut 10 (P396L, A330S, K288N); Mut 18 (K326E); Mut 14 (K334E, K288N); Mut 11 (R255L, F243L); Mut 16 (F372Y); Mut 19 (K334N, K2461).

[0139] FIGS. 18 A-H Analysis of Kinetic Parameters of FcγRIIIA Binding to Antibodies Carrying Variant Fc Regions

[0140] Kinetic parameters for FcγRIIIA binding to antibodies carrying variant Fc regions were obtained by generating separate best fit curves for 200 nM and 800 nM. Solid line indicates an association fit which was obtained based on the k_off values calculated for the dissociation curves in the 32-34 sec interval. K_d and k_off values represent the average from two concentrations.

[0141] FIG. 19 Sensogram of Real Time Binding of FcγRIIB-Fc Fusion Proteins to Antibodies Carrying Variant Fc Regions

[0142] Binding of FcγRIIB-Fc fusion proteins to ch-4-4-20 antibodies carrying variant Fc regions was analyzed at 200 nM concentration. Responses were normalized at the level of ch-4-4-20 antibody obtained for wild type.

[0143] FIGS. 20 A-C Analysis of Kinetic Parameters FcγRIIB-Fc Fusion Proteins to Antibodies Carrying Variant Fc Regions

[0144] Kinetic parameters for FcγRIIB-Fc binding to antibodies carrying variant Fc regions were obtained by generating separate best fit curves for 200 nM and 800 nM. Solid line indicates an association fit which was obtained based on the k_off values calculated for the dissociation curves in the 32-34 sec. interval. K_d and K_off values represent the average from two concentrations.

[0145] Mutants used were as follows: Mut 6 (S219V), Mut 10 (P396L, A330S, K288N); Mut 18 (K326E); Mut 14 (K334E, K288N); Mut 11 (R255L, F243L); Mut 16 (F372Y); Mut 19 (K334N, K246I).

[0146] FIG. 21 Ratios of K_off (WT)/K_off (MUT) for FcγRIIIA-Fc Plotted Against ADCC Data

[0147] Numbers higher than one show a decreased dissociation rate for FcγRIIIA binding and increased dissociation rate for FcγRIIB-Fc binding relative to wild-type. Mutants in the box have lower off rate for FcγRIIIA binding and higher off rate for FcγRIIB-Fc binding.

[0148] FIG. 22 Competition with Unlabeled FcγRIIIA

[0149] A kinetic screen was implemented to identify Fc region mutants with improved K_off rates for binding FcγRIIIA. A library of Fc region variants containing P396L mutation was incubated with 0.1 μM biotinylated FcγRIIIA-Linker-Avitag for one hour and then washed. Subsequently 0.8 uM unlabeled FcγRIIIA was incubated with the labeled yeast for different time points. Yeast was spun down and unlabeled FcγRIIIA was removed, Receptor bound yeast was stained with SA (streptavidin):PE (phycoerythrin) for FACS analysis.

[0150] FIGS. 23 A-C FACS Analysis Based on the Kinetic Screen

[0151] Based on the calculated K_off from the data presented in FIG. 22, a one minute time point selection was chosen. A 10-fold excess of library was incubated with 0.1 μM biotinylated FcγRIIIA-Linker-Avitag monomer; cells were washed and incubated with unlabeled ligand for one minute; then washed and labeled with SA:PE. The cells were then sorted by FACS, selecting the top 0.3% binders. The nonselected P396L library was compared to the yeast cells selected for improved binding by FACS. The histograms show the percentage of cells that are contained with both FcγRIIIA/PE and goat anti-human Fc/FITC.

[0152] FIGS. 24 A-B Selection Based on Solid Phase Depletion of FcγRIIB Fc Binders

[0153] A. The P396L library was screened based on FcγRIIB depletion and FcγRIIIA selection using magnetic beads. The FcγRIIB depletion by magnetic beads was repeated 5 times. The resulting yeast population was analyzed and found to show greater than 50% cell staining with goat anti-human Fc and a very small percentage of cells stained with FcγRIIIA. Subsequently cells were selected twice by FACS using 0.1 μM biotinylated FcγRIIIA linker-avitag. Yeast cells were analyzed for both FcγRIIIA and FcγRIIB binding after each sort and compared to wild type binding.

[0154] B. Fc Mutants were selected from the FcγRIIB depleted yeast population using biotinylated FcγRIIIA 158F linker avitag monomer as a ligand. The sort gate was set to select the top 0.25% FcγRIIIA 158F binders. The resulting enriched population was analyzed by FACS for binding to the different FcγRIIIA (158F and 158V), FcγRIIIB and FcγRIIA (131 R).

[0155] FIG. 25 Relative Rates OF SKBR3 Target Cell Lysis Mediated by Chimeric 4D5 Harboring FC Mutants

[0156] Relative rates of lysis was calculated for each Fc mutant tested. Lysis rates for 4D5 antibody with Fc mutants were divided by the rate of lysis mediated by wild type 4D5 antibody. Data from at least 2 independent assays were averaged and plotted on the histogram. For each Fc mutant data from two different antibody concentrations are shown. The antibody concentrations were chosen to flank the point along the curve at which lysis was ˜50%.

[0157] FIG. 26 Relative Rates of Daudi Cell Lysis Mediated by Chimeric 2H7 Harboring FC Mutants

[0158] Relative rates of lysis was calculated for each Fc mutant tested. Lysis rates for 2H7 antibody with Fc mutants were divided by the rate of lysis mediated by wild type 2H7 antibody. Data from at least 1-2 independent assays were averaged and plotted on the histogram. For each Fc mutant, data from two different antibody concentrations are shown The antibody concentrations were chosen based on the point along the curve at which lysis was ˜50%.

[0159] FIG. 27 Scheme for Library Production.

[0160] DNA strands are represented. Forward arrows represent primers containing mutant codons. Reverse arrow represent reverse gene specific oligo.

[0161] FIG. 28 Strategy for Production of Libraries by Build a Gene Protocol.

[0162] The rectangular boxes represent the hinge, CH2, and CH3 domains, respectively. The short black lines represent the double stranded oligos with 5′ overhangs.

[0163] FIG. 29 Novel Fc Mutants Improve PBMC Mediated ADCC in SKBR3 Cells.

[0164] The plot shows linear regression analysis of a standard ADCC assay. Antibody was titrated over 3 logs using an effector to target ratio of 75:1. % lysis=(Experimental release−SR)/(MR−SR)*100.

[0165] FIG. 30 Novel Fc Mutants Improve PBMC Mediated ADCC in Daudi Cells.

[0166] The plot shows linear regression analysis of a standard ADCC assay. Antibody was titrated over 3 logs using an effector to target ratio of 75:1. % lysis=(Experimental release−SR)/(MR−SR)*100.

[0167] FIG. 31 Fc Receptor Profiles VIA FACS Upon Cytokine Treatment of Monocytes.

[0168] Cytokine treatment of monocytes increases low affinity Fc receptor expression Elutriated monocytes were cultured using specific cytokines in serum free media. Fc receptor profiles were assayed using FACS.

[0169] FIG. 32 Improved Tumor Cell Killing Using FC Mutants in Macrophage-Derived Monocytes Based ADCC.

[0170] Ch4D5 MAb concentration over 2 logs was tested using effector:target ratio of 35:1. Percent lysis was calculated as in FIG. 30.

[0171] FIG. 33 Complement Dependent Cytotoxicity Assay Flow Chart.

[0172] The flow chart summarizes the CDC assays used.

[0173] FIG. 34 Complement Dependent Cytotoxicity Activity

[0174] Fc mutants that show enhanced binding to FcγRIIIA also showed improved complement activity. Anti-CD20 ChMAb over 3 orders of magnitude was titrated. Percent lysis was calculated as in as in FIG. 30.

[0175] FIG. 35 Decision Tree for Selection of Fc Mutants

[0176] An exemplary protocol for selecting Fc mutants.

[0177] FIG. 36 C1q Binding to 2B6 Antibody

[0178] A. The diagram depicts the BIAcore format for analysis of 2B6 binding to the first component of the complement cascade.

[0179] B. Sensogram of real time binding of 2B6 antibody carrying variant Fc regions to C1q.

[0180] FIGS. 37 A-D C1q Binding to 2B6 Mutant Antibody.

[0181] Sensogram of real time binding of 2B6 mutants to C1q (3.25 nM). Mutants depicted at MgFc51 (Q419H, P396L); MgFc51/60 in Panel A; MgFc55 and MgFc55/60 (Panel B), MgFc59 and MgFc59/60 (Panel C); and MgFc31/60 (Panel D).

[0182] FIGS. 38 A-D Fc Variants with Decreased Binding to FcγRIIB

[0183] Binding of FcR to ch4D5 antibodies to compare effect of D270E (60) on R255L, P396L double mutant (MgFc55). K_D was analyzed at different concentrations of FcR; 400 nM CD16A 158V; 800 nM CD16A 158F; 200 nM CD32B; 200 nM CD32A 131H. Analysis was performed using separate K_D using Biacore 3000 software.

[0184] FIGS. 39 A-D Kinetic Characteristics of 4D5 Mutants Selected from FcγRIIB Depletions/FcγRIIAH131 Selection

[0185] Binding of FcR to ch4D5 antibodies carrying different Fc mutations selected by CD32B depletion and CD32A H131 screening strategy. K_D was analyzed at different concentrations of FcR; 400 nM CD16A 158V; 800 nM CD16A 158F; 200 nM CD32B; 200 nM CD32A 131H. Analysis was performed using separate K_D using Biacore 3000 software.

[0186] FIG. 40. Plot of MDM ADCC Data Against the K_OFF Determined for CD32A 131H Binding as Determined by Biacore.

[0187] The mutants are as follows: MgFc 25 (E333A, K334A, S298A); MgFc68 (D270E); MgFc38 (K392T, P396L); MgFc55 (R255L, P396L); MgFc31 (P247L, N421K); MgFc59 (K370E, P396L).

[0188] FIGS. 41 A-B. ADCC Activity of Mutants in a HER2/NEU Chimeric Monoclonal Antibody

[0189] Chimeric HER2/neu monoclonal antibodies containing mutant Fc regions were assessed, in duplicate, for their ADCC activity and compared to the ADCC activity of the wild type, chimeric Her2/neu antibody. The mutants analyzed are as follows: MGFc88 (F243L, R292P, Y300L, V3051, P396L), MGFc88A (F243L, R292P, Y300L, P396L), MGFc155 (F243L, R292P, Y300L).

[0190] FIGS. 42 A-B. Estimated Tumor Weight in Mice Treated with Wild-Type or Fc Mutant h2B6

[0191] Balb/c nude mice were inoculated subcutaneously with Daudi cells and administered 25 μg, 2.5 μg or 0.25 μg weekly doses of either wild-type h2B6 (A) or h2B6 harboring Fc mutant MGFc 0088 (F243L, R292P, Y300L, V3051, P396L) (B). Mice administered buffer alone were used as control. Tumor weight was calculated based on the estimated volume of the subcutaneous tumor according to the formula (width²×length)/2.

[0192] FIGS. 43 A-B. Survival in Tumor Bearing Mice Treated with Wild-Type or Fc Mutant h2B6

[0193] Nude mice were inoculated with Daudi cells and administered 25 μg, 2.5 μg or 0.25 μg weekly doses of either wild-type h2B6 (A) or h2B6 harboring Fc mutant MGFc 0088 (F243L, R292P, Y300L, V3051, P396L) (B). Mice administered buffer alone were used as control.

[0194] The present invention relates to molecules, preferably polypeptides, and more preferably immunoglobulins (e.g., antibodies), comprising a variant Fc region, having one or more amino acid modifications (e.g., substitutions, but also including insertions or deletions) in one or more regions, which modifications alter, e.g., increase or decrease, the affinity of the variant Fc region for an FcγR. In some embodiments, the invention comprises modifications to the Fc region including but not limited to any of the modifications disclosed in U.S. application Ser. No. 10/754,922 filed Jan. 9, 2004; U.S. Provisional Application Ser. No. 60/439,498 filed Jan. 9, 2003; U.S. Provisional Application Ser. No. 60/456,041 filed Mar. 19, 2003; U.S. Provisional Application Ser. No. 60/514,549 filed Oct. 23, 2003 and U.S. Provisional Application Ser. No. 60/587,251 filed Jul. 12, 2004. Each of the above mentioned applications is incorporated herein by reference in its entirety. In some embodiments, the invention provides molecules comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, which variant Fc region binds FcγRIIIA with a greater affinity, relative to a comparable molecule, i.e., being the same as said molecule with a variant Fc region but not having the one or more amino acid modifications, comprising the wild-type Fc region as determined by methods known to one skilled in the art for determining Fc-FcγR interactions and methods disclosed herein, for example, an ELISA assay or a surface plasmon resonance assay. In yet other embodiments, the invention encompasses molecules comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, which variant Fc region binds FcγRIIIA with a reduced affinity relative to a comparable molecule comprising the wild-type Fc region. In a preferred embodiment, the molecules of the invention further specifically bind FcγRIIB (via the Fc region) with a lower affinity than a comparable molecule comprising the wild-type Fc region binds FcγRIIB. In some embodiments, the invention encompasses molecules comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, which variant Fc region binds FcγRIIIA and FcγRIIB with a greater affinity, relative to a comparable molecule comprising the wild-type Fc region. In other embodiments, the invention encompasses molecules comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, which variant Fc region binds FcγRIIB with a greater affinity, relative to a comparable molecule comprising the wild-type Fc region. In other embodiments, the invention encompasses molecules comprising variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, which variant Fc region binds FcγRIIB with a reduced affinity, relative to a comparable molecule comprising the wild-type Fc region.

[0195] In some embodiments, the invention encompasses molecules comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild type Fc region, which variant Fc region does not show a detectable binding to any FcγR (e.g., does not bind FcγRIIA, FcγRIIB, or FcγRIIIA, as determined by, for example, an ELISA assay), relative to a comparable molecule comprising the wild-type Fc region.

[0196] In a specific embodiment, the invention encompasses molecules comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild type Fc region, which variant Fc region only binds one FcγR, wherein said FcγR is FcγIIIA. In another specific embodiment, the invention encompasses molecules comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild type Fc region, which variant Fc region only binds one FcγR, wherein said FcγR is FcγRIIA. In yet another embodiment, the invention encompasses molecules comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild type Fc region, which variant Fc region only binds one FcγR, wherein said FcγR is FcγRIIB. The invention particularly relates to the modification of human or humanized therapeutic antibodies (e.g., tumor specific anti-angiogenic or anti-inflammatory monoclonal antibodies) for enhancing the efficacy of therapeutic antibodies by enhancing, for example, the effector function of the therapeutic antibodies, e.g., enhancing ADCC.

[0197] The affinities and binding properties of the molecules of the invention for an FcγR are initially determined using in vitro assays (biochemical or immunological based assays) known in the art for determining Fc-FcγR interactions, i.e., specific binding of an Fc region to an FcγR including but not limited to ELISA assay, surface plasmon resonance assay, immunoprecipitation assays (See Section 5.2.5.1). Preferably, the binding properties of the molecules of the invention are also characterized by in vitro functional assays for determining one or more FcγR mediator effector cell functions (See Section 5.2.7). In most preferred embodiments, the molecules of the invention have similar binding properties in in vivo models (such as those described and disclosed herein) as those in in vitro based assays However, the present invention does not exclude molecules of the invention that do not exhibit the desired phenotype in in vitro based assays but do exhibit the desired phenotype in vivo.

[0198] In some embodiments, the molecules of the invention comprising a variant Fc region comprise at least one amino acid modification in the CH3 domain of the Fc region, which is defined as extending from amino acids 342-447. In other embodiments, the molecules of the invention comprising a variant Fc region comprise at least one amino acid modification in the CH2 domain of the Fc region, which is defined as extending from amino acids 231-341. In some embodiments, the molecules of the invention comprise at least two amino acid modifications, wherein one modification is in the CH3 region and one modification is in the CH2 region. The invention further encompasses amino acid modification in the hinge region. Molecules of the invention with one or more amino acid modifications in the CH2 and/or CH3 domains have altered affinities for an FcγR as determined using methods described herein or known to one skilled in the art.

[0199] In a particular embodiment, the invention encompasses amino acid modification in the CH1 domain of the Fc region.

[0200] In particularly preferred embodiments, the invention encompasses molecules comprising a variant Fc region wherein said variant has an increased binding to FcγRIIA (CD32A) and/or an increased ADCC activity, as measured using methods known to one skilled in the art and exemplified herein. The ADCC assays used in accordance with the methods of the invention may be NK dependent or macrophage dependent.

[0201] The Fc variants of the present invention may be combined with other known Fc modifications including but not limited to modifications which alter effector function and modification which alter FcγR binding affinity. In a particular embodiment, an Fc variant of the invention comprising a first amino acid modification in the CH3 domain, CH2 domain or the hinge region may be combined with a second Fc modification such that the second Fc modification is not in the same domain as the first so that the first Fc modification confers an additive, synergistic or novel property on the second Fc modification. In some embodiments, the Fc variants of the invention do not have any amino acid modification in the CH2 domain.

[0202] The Fc variants of the present invention may be combined with any of the known Fc modifications in the art such as those disclosed in Table 2 below.

TABLE 2
Substitution(s)
	V264A
	V264L
	V264I
	F241W
	F241L
	F243W
	F243L
	F241L/F243L/V262I/V264I
	F241W/F243W
	F241W/F243W/V262A/V264A
	F241L/V262I
	F243L/V2641
	F243L/V262I/V264W
	F241Y/F243Y/V262T/V264T
	F241E/F243R/V262E/V264R
	F241E/F243Q/V262T/V264E
	F241R/F243Q/V262T/V264R
	F241E/F243Y/V262T/V264R
	L328M
	L328E
	L328F
	I332E
	L328M/I332E
	P244H
	P245A
	P247V
	W313F
	P244H/P245A/P247V
	P247G
	V264I/I332E
	F241E/F243R/V262E/V264R/I332E
	F241E/F243Q/V262T/V264E/I332E
	F241R/F243Q/V262T/V264R/I332E
	F241E/F243Y/V262T/V264R/I332E
	S298A
	S298A/I332E
	S298A/E333A/K334A
	S239E/I332E
	S239Q/I332E
	S239E
	D265G
	D265N
	S239E/D265G
	S239E/D265N
	S239E/D265Q
	Y296E
	Y296Q
	S298T
	S298N
	T299I
	A327S
	A327N
	S267Q/A327S
	S267L/A327S
	A327L
	P329F
	A330L
	A330Y
	I332D
	N297S
	N297D
	N297S/I332E
	N297D/I332E
	N297E/I332E
	D265Y/N297D/I332E
	D265Y/N297D/T299L/I332E
	D265F/N297E/I332E
	L328I/I332E
	L328Q/I332E
	I332N
	I332Q
	V264T
	V264F
	V240I
	V263I
	V266I
	T299A
	T299S
	T299V
	N325Q
	N325L
	N325I
	S239D
	S239N
	S239F
	S239D/I332D
	S239D/I332E
	S239D/I332N
	S239D/I332Q
	S239E/I332D
	S239E/I332N
	S239E/I332Q
	S239N/I332D
	S239N/I332E
	S239N/I332N
	S239N/I332Q
	S239Q/I332D
	S239Q/I332N
	S239Q/I332Q
	K326E
	Y296D
	Y296N
	F241Y/F243Y/V262T/V264T/N297D/I332E
	A330Y/I332E
	V264I/A330Y/I332E
	A330L/I332E
	V264I/A330L/I332E
	L234D
	L234E
	L234N
	L234Q
	L234T
	L234H
	L234Y
	L234I
	L234V
	L234F
	L235D
	L235S
	L235N
	L235Q
	L235T
	L235H
	L235Y
	L235I
	L235V
	L235F
	S239T
	S239H
	S239Y
	V240A
	V240T
	V240M
	V263A
	V263T
	V263M
	V264M
	V264Y
	V266A
	V266T
	V266M
	E269H
	E269Y
	E269F
	E269R
	Y296S
	Y296T
	Y296L
	Y296I
	A298H
	T299H
	A330V
	A330I
	A330F
	A330R
	A330H
	N325D
	N325E
	N325A
	N325T
	N325V
	N325H
	L328D/I332E
	L328E/I332E
	L328N/I332E
	L328Q/I332E
	L328V/I332E
	L328T/I332E
	L328H/I332E
	L328I/I332E
	L328A
	I332T
	I332H
	I332Y
	I332A
	S239E/V264I/I332E
	S239Q/V264I/I332E
	S239E/V264I/A330Y/I332E
	S239E/V264I/S298A/A330Y/I332E
	S239D/N297D/I332E
	S239E/N297D/I332E
	S239D/D265V/N297D/I332E
	S239D/D265I/N297D/I332E
	S239D/D265L/N297D/I332E
	S239D/D265F/N297D/I332E
	S239D/D265Y/N297D/I332E
	S239D/D265H/N297D/I332E
	S239D/D265T/N297D/I332E
	V264I/N297D/I332E
	Y296D/N297D/I332E
	Y296E/N297D/I332E
	Y296N/N297D/I332E
	Y296Q/N297D/I332E
	Y296H/N297D/I332E
	Y296T/N297D/I332E
	N297D/T299V/I332E
	N297D/T299I/I332E
	N297D/T299L/I332E
	N297D/T299F/I332E
	N297D/T299H/I332E
	N297D/T299E/I332E
	N297D/A330Y/I332E
	N297D/S298A/A330Y/I332E
	S239D/A330Y/I332E
	S239N/A330Y/I332E
	S239D/A330L/I332E
	S239N/A330L/I332E
	V264I/S298A/I332E
	S239D/S298A/I332E
	S239N/S298A/I332E
	S239D/V264I/I332E
	S239D/V264I/S298A/I332E
	S239D/V264I/A330L/I332E
	T256A
	K290A
	D312A
	*K326A
	S298A
	E333A
	K334A
	E430A
	T359A
	K360A
	E430A
	K320M
	K326S
	K326N
	K326D
	K326E
	K334Q
	K334E
	K334M
	K334H
	K334V
	K334L
	A330K
	T335K
	A339T
	E333A, K334A
	T256A, S298A
	T256A, D280A, S298A, T307A
	S298A, E333A, K334A S298A, K334A
	S298A, E333A
	T256A
	K290A
	K326A
	R255A
	E258A
	S267A
	E272A
	N276A
	D280A
	E283A
	H285A
	N286A
	P331A
	S337A
	H268A
	E272A
	E430A
	A330K
	R301M
	H268N
	H268S
	E272Q
	N286Q
	N286S
	N286D
	K290S
	K320M
	K320Q
	K320E
	K320R
	K322E
	K326S
	K326D
	K326E
	A330K
	T335E
	S267A, E258A
	S267A, R255A
	S267A, D280A
	S267A, E272A
	S267A, E293A
	S267A, E258A, D280A, R255A
	P238A
	D265A
	E269A
	D270A
	N297A
	P329A
	A327Q
	S239A
	E294A
	Q295A
	V303A
	K246A
	I253A
	T260A
	K274A
	V282A
	K288A
	Q311A
	K317A
	E318A
	K338A
	K340A
	Q342A
	R344A
	E345A
	Q347A
	R355A
	E356A
	M358A
	K360A
	N361A
	Q362A
	Y373A
	S375A
	D376A
	E380A
	E382A
	S383A
	N384A
	Q386A
	E388A
	N389A
	N390A
	Y391A
	K392A
	L398A
	S400A
	D401A
	D413A
	K414A
	S415A
	R416A
	Q418A
	Q419A
	N421A
	V422A
	S424A
	E430A
	H433A
	N434A
	H435A
	Y436A
	T437A
	Q438A
	K439A
	S440A
	S442A
	S444A
	K447A
	K246M
	K248M
	Y300F
	A330Q
	K338M
	K340M
	A378Q
	Y391F

[0203] In other embodiments, the Fc variants of the present invention may be combined with any of the known Fc modifications in the art such as those disclosed in Tables 3 A and B below.

TABLE 3A
Starting	Position	Position	Position	Position	Position
Variant	300	298	296	295	294
Y3001 + →	—	S298N, S298V,	Y296P, Y296F,	Q295K, Q295L,	E294N, E294A,
		S298D, S298P,	or N276Q.	or Q295A.	E294Q, or
		S298A, S298G,			E294D.
		S298T, or
		S298L.
Y300L + →	—	S298N, S298V,	Y296P, Y296F,	Q295K, Q295L,	E294N, E294A,
		S298D, S298P,	or N276Q.	or Q295A.	E294Q, or
		S298A, S298G,			E294D.
		S298T, or
		S298L.
S298N + →	Y3001, Y300L,	—	Y296P, Y296F,	Q295K, Q295L,	E294N, E294A,
	or Y300F.		or N276Q.	or Q295A.	E294Q, or
					E294D.
S298V + →	Y3001, Y300L,	—	Y296P, Y296F,	Q295K, Q295L,	E294N, E294A,
	or Y300F.		or N276Q.	or Q295A.	E294Q, or
					E294D.
S298D + →	Y3001, Y300L,	—	Y296P, Y296F,	Q295K, Q295L,	E294N, E294A,
	or Y300F.		or N276Q.	or Q295A.	E294Q, or
					E294D.
S298P + →	Y3001, Y300L,	—	Y296P, Y296F,	Q295K, Q295L,	E294N, E294A,
	or Y300F.		or N276Q.	or Q295A.	E294Q, or
					E294D.
Y296P + →	Y3001, Y300L,	S298N, S298V,	—	Q295K, Q295L,	E294N, E294A,
	or Y300F.	S298D, S298P,		or Q295A.	E294Q, or
		S298A, S298G,			E294D.
		S298T, or
		S298L.
Q295K + →	Y3001, Y300L,	S298N, S298V,	Y296P, Y296F,	—	E294N, E294A,
	or Y300F.	S298D, S298P,	or N276Q.		E294Q, or
		S298A, S298G,			E294D.
		S298T, or
		S298L.
Q295L + →	Y3001, Y300L,	S298N, S298V,	Y296P, Y296F,	—	E294N, E294A,
	or Y300F.	S298D, S298P,	or N276Q.		E294Q, or
		S298A, S298G,			E294D.
		S298T, or
		S298L.
E294N + →	Y3001, Y300L,	S298N, S298V,	Y296P, Y296F,	Q295K, Q295L,	—
	or Y300F.	S298D, S298P,	or N276Q.	or Q295A.
		S298A, S298G,
		S298T, or
		S298L.
**Note that table uses EU numbering as in Kabat.

[0204]

TABLE 3B
Starting	Position	Position	Position	Position	Position
Variant	334	333	324	286	276
Y3001 + →	K334A, K334R, K334Q,	E33A, E333Q,	S324A,	N286Q,	N276Q,
	K334N, K334S, K334E,	E333N, E333S,	S324N,	N286S,	N276A, or
	K334D, K334M, K334Y,	E333K, E333R,	S324Q,	N286A, or	N276K.
	K334W, K334H, K334V,	E333D, or	S324K, or	N286D.
	or K334L.	E333G.	S324E.
Y300L + →	K334A, K334R, K334Q,	E33A, E333Q,	S324A,	N286Q,	N276Q,
	K334N, K334S, K334E,	E333N, E333S,	S324N,	N286S,	N276A, or
	K334D, K334M, K334Y,	E333K, E333R,	S324Q,	N286A, or	N276K.
	K334W, K334H, K334V,	E333D, or	S324K, or	N286D.
	or K334L.	E333G.	S324E.
S298N + →	K334A, K334R, K334Q,	E33A, E333Q,	S324A,	N286Q,	N276Q,
	K334N, K334S, K334E,	E333N, E333S,	S324N,	N286S,	N276A, or
	K334D, K334M, K334Y,	E333K, E333R,	S324Q,	N286A, or	N276K.
	K334W, K334H, K334V,	E333D, or	S324K, or	N286D.
	or K334L.	E333G.	S324E.
S298V + →	K334A, K334R, K334Q,	E33A, E333Q,	S324A,	N286Q,	N276Q,
	K334N, K334S, K334E,	E333N, E333S,	S324N,	N286S,	N276A, or
	K334D, K334M, K334Y,	E333K, E333R,	S324Q,	N286A, or	N276K.
	K334W, K334H, K334V,	E333D, or	S324K, or	N286D.
	or K334L.	E333G.	S324E.
S298D + →	K334A, K334R, K334Q,	E33A, E333Q,	S324A,	N286Q,	N276Q,
	K334N, K334S, K334E,	E333N, E333S,	S324N,	N286S,	N276A, or
	K334D, K334M, K334Y,	E333K, E333R,	S324Q,	N286A, or	N276K.
	K334W, K334H, K334V,	E333D, or	S324K, or	N286D.
	or K334L.	E333G.	S324E.
S298P + →	K334A, K334R, K334Q,	E33A, E333Q,	S324A,	N286Q,	N276Q,
	K334N, K334S, K334E,	E333N, E333S,	S324N,	N286S,	N276A, or
	K334D, K334M, K334Y,	E333K, E333R,	S324Q,	N286A, or	N276K.
	K334W, K334H, K334V,	E333D, or	S324K, or	N286D.
	or K334L.	E333G.	S324E.
Y296P + →	K334A, K334R, K334Q,	E33A, E333Q,	S324A,	N286Q,	N276Q,
	K334N, K334S, K334E,	E333N, E333S,	S324N,	N286S,	N276A, or
	K334D, K334M, K334Y,	E333K, E333R,	S324Q,	N286A, or	N276K.
	K334W, K334H, K334V,	E333D, or	S324K, or	N286D.
	or K334L.	E333G.	S324E.
Q295K + →	K334A, K334R, K334Q,	E33A, E333Q,	S324A,	N286Q,	N276Q,
	K334N, K334S, K334E,	E333N, E333S,	S324N,	N286S,	N276A, or
	K334D, K334M, K334Y,	E333K, E333R,	S324Q,	N286A, or	N276K.
	K334W, K334H, K334V,	E333D, or	S324K, or	N286D.
	or K334L.	E333G.	S324E.
Q295L + →	K334A, K334R, K334Q,	E33A, E333Q,	S324A,	N286Q,	N276Q,
	K334N, K334S, K334E,	E333N, E333S,	S324N,	N286S,	N276A, or
	K334D, K334M, K334Y,	E333K, E333R,	S324Q,	N286A, or	N276K.
	K334W, K334H, K334V,	E333D, or	S324K, or	N286D.
	or K334L.	E333G.	S324E.
E294N + →	K334A, K334R, K334Q,	E33A, E333Q,	S324A,	N286Q,	N276Q,
	K334N, K334S, K334E,	E333N, E333S,	S324N,	N286S,	N276A, or
	K334D, K334M, K334Y,	E333K, E333R,	S324Q,	N286A, or	N276K.
	K334W, K334H, K334V,	E333D, or	S324K, or	N286D.
	or K334L.	E333G.	S324E.
**Note that table uses EU numbering as in Kabat.

[0205] In a preferred specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said molecule has an altered affinity for an FcγR, provided that said variant Fc region does not have a substitution at positions that make a direct contact with FcγR based on crystallographic and structural analysis of Fc-FcγR interactions such as those disclosed by Sondermann et al., 2000 (Nature, 406: 267-273 which is incorporated herein by reference in its entirety). Examples of positions within the Fc region that make a direct contact with FcγR are amino acids 234-239 (hinge region), amino acids 265-269 (B/C loop), amino acids 297-299 (C′/E loop), and amino acids 327-332 (F/G) loop. In some embodiments, the molecules of the invention comprising variant Fc regions comprise modification of at least one residue that makes a direct contact with an FcγR based on structural and crystallographic analysis.

[0206] The FcγR interacting domain maps to the lower hinge region and select sites within the CH2 and CH3 domains of the IgG heavy chain. Amino acid residues flanking the actual contact positions and amino acid residues in the CH3 domain play a role in IgG/FcγR interactions as indicated by mutagenesis studies and studies using small peptide inhibitors, respectively (Sondermann et al., 2000 Nature, 406: 267-273; Diesenhofer et al., 1981, Biochemistry, 20: 2361-2370; Shields et al., 2001, J. Biol. Chem. 276: 6591-6604; each of which is incorporated herein by reference in its entirety). Direct contact as used herein refers to those amino acids that are within at least 1 Å, at least 2, or at least 3 angstroms of each other or within 1 Å, 1.2 Å, 1.5 Å, 1.7 Å or 2 Å Van Der Waals radius. An exemplary list of previously identified sites on the Fc that effect binding of Fc interacting proteins is listed in the Table 4 below. In some embodiments, the invention encompasses Fc variants that do not have any modifications at the sites listed below. In other embodiments, the invention encompasses Fc variants comprising amino acid modifications at one or more sites listed below in combination with other modifications disclosed herein such that such modification has a synergistic or additive effect on the property of the mutant.

TABLE 4
PREVIOUSLY IDENTIFIED SITES ON THE Fc THAT EFFECT
BINDING OF Fc INTERACTING PROTEINS.
FcR-Fc	Domain	residue	FcRI	FcRII	FcRIII	C1q	FcRn
	CH2	233	C	C	C		C
A, B	CH2	234	C	C	C	G	C
A, B	CH2	235	C	C	C	G	C
A, B	CH2	236	C	C	C		C
A, B	CH2	237
A, B	CH2	238	D
A, B	CH2	239			C
	CH2	241	D
	CH2	243	D
	CH2	246	D
	CH2	250					E
	CH2	254					C
	CH2	255		C
	CH2	256		C	C
	CH2	258		C
B	CH2	265	C	C	C	F	C
B	CH2	267		C
	CH2	268		C	C
B	CH2	269			C
	CH2	270		C	C	F
	CH2	272		C
	CH2	276		C
	CH2	285		C
	CH2	286		C
	CH2	288					C
	CH2	290		C	C
	CH2	292		C
	CH2	293			C
	CH2	295		C	C
	CH2	296			C
B	CH2	297	X	X	X	X
B	CH2	298
B	CH2	299
	CH2	301	D	C	C
	CH2	311					C
	CH2	312					C
	CH2	315		C
	CH2	317					C
	CH2	322		C	C	F
	CH2	326		C		F
A, B	CH2	327	D, C	C	C
A	CH2	328
A	CH2	329	D, C	C	C	F
A	CH2	330
	CH2	331		C		F
A	CH2	332
	CH2	333			C	F
	CH2	334			C
	CH2	337		C
	CH2	338			C
	CH3	339			C
	CH3	360					C
	CH3	362					C
	CH3	376			C
	CH3	378		C
	CH3	380					C
	CH3	382					C
	CH3	414		C
	CH3	415					C
	CH3	424					C
	CH3	428					E
	CH3	430		C
	CH3	433					C
	CH3	434					C
	CH3	435					C
	CH3	436					C

[0207] Table 4 lists sites within the Fc region that have previously been identified to be important for the Fc-FcR interaction. Columns labeled FcR-Fc identifies the Fc chain contacted by the FcR. Letters identify the reference in which the data was cited. C is Shields et al., 2001, J. Biol. Chem. 276: 6591-6604; D is Jefferis et al., 1995, Immunol. Lett. 44: 111-7; E is Hinton et al; 2004, J. Biol. Chem. 279(8): 6213-6; F is Idusogie et al., 2000, J. Immunol. 164: 4178-4184; each of which is incorporated herein by reference in its entirety.

[0208] In another preferred embodiment, the invention encompasses a molecule. comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said molecule binds an FcγR with an altered affinity relative to a molecule comprising a wild-type Fc region, provided that said variant Fc region does not have or is not solely a substitution at any of positions 255, 256, 258, 267, 268, 269, 270, 272, 276, 278, 280, 283, 285, 286, 289, 290, 292, 293, 294, 295, 296, 298, 300, 301, 303, 305, 307, 309, 312, 320, 322, 326, 329, 330, 332, 331, 333, 334, 335, 337, 338, 339, 340, 359, 360, 373, 376, 416, 419, 430, 434, 435, 437, 438, 439. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said molecule binds an FcγR with an altered affinity relative to a molecule comprising a wild-type Fc region, provided that said variant Fc region does not have or is not solely a substitution at any of positions 255, 258, 267, 269, 270, 276, 278, 280, 283, 285, 289, 292, 293, 294, 295, 296, 300, 303, 305, 307, 309, 322, 329, 332, 331, 337, 338, 340, 373, 376, 416, 419, 434, 435, 437, 438, 439 and does not have an alanine at any of positions 256, 290, 298, 312, 333, 334, 359, 360, 326, or 430; a lysine at position 330; a threonine at position 339; a methionine at position 320; a serine at position 326; an asparagine at position 326; an aspartic acid at position 326; a glutamic acid at position 326; a glutamine at position 334; a glutamic acid at position 334; a methionine at position 334; a histidine at position 334; a valine at position 334; or a leucine at position 334; a lysine at position 335 an asparagine at position 268; a glutamine at position 272; a glutamine, serine, or aspartic acid at position 286; a serine at position 290; a methionine, glutamine, glutamic acid, or arginine at position 320; a glutamic acid at position 322; a serine, glutamic acid, or aspartic acid at position 326; a lysine at position 330; a glutamine at position 335; or a methionine at position 301.

[0209] In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region does not have or is not solely a substitution at any of positions 268, 269, 270, 272, 276, 278, 283, 285, 286, 289, 292, 293, 301, 303, 305, 307, 309, 331, 333, 334, 335, 337, 338, 340, 360, 373, 376, 416, 419, 430, 434, 435, 437, 438 or 439 and does not have a histidine, glutamine, or tyrosine at position 280; a serine, glycine, threonine or tyrosine at position 290, a leucine or isoleucine at position 300; an asparagine at position 294, a proline at position 296; a proline, asparagine, aspartic acid, or valine at position 298; a lysine at position 295. In yet another preferred embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said molecule binds an FcγR with a reduced affinity relative to a molecule comprising a wild-type Fc region provided that said variant Fc region does not have or is not solely a substitution at any of positions 252, 254, 265, 268, 269, 270, 278, 289, 292, 293, 294, 295, 296, 298, 300, 301, 303, 322, 324, 327, 329, 333, 335, 338, 340, 373, 376, 382, 388, 389, 414, 416, 419, 434, 435, 437, 438, or 439. In yet another preferred embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said molecule binds an FcγR with an enhanced affinity relative to a molecule comprising a wild-type Fc region provided that said variant Fc region does not have or is not solely a substitution at any of positions 280, 283, 285, 286, 290, 294, 295, 298, 300, 301, 305, 307, 309, 312, 315, 331, 333, 334, 337, 340, 360, 378, 398, or 430.

[0210] In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region does not include or are not solely a substitution at any of positions 330, 243, 247, 298, 241, 240, 244, 263, 262, 235, 269, or 328 and does not have a leucine at position 243, an asparagine at position 298, a leucine at position 241, and isoleucine or an alanine at position 240, a histidine at position 244, a valine at position 330, or an isoleucine at position 328.

[0211] In most preferred embodiments, the molecules of the invention with altered affinities for activating and/or inhibitory receptors having variant Fc regions, have one or more amino acid modifications, wherein said one or more amino acid modification is a substitution at position 288 with asparagine, at position 330 with serine and at position 396 with leucine (MgFc10)(See Tables 5 & 6); or a substitution at position 334 with glutamic acid, at position 359 with asparagine, and at position 366 with serine (MgFc13); or a substitution at position 316 with aspartic acid, at position 378 with valine, and at position 399 with glutamic acid (MgFc27); or a substitution at position 392 with threonine, and at position 396 with leucine (MgFc38); or a substitution at position 221 with glutamic acid, at position 270 with glutamic acid, at position 308 with alanine, at position 311 with histidine, at position 396 with leucine, and at position 402 with aspartic acid (MgFc42); or a substitution at position 240 with alanine, and at position 396 with leucine (MgFc52); or a substitution at position 410 with histidine, and at position 396 with leucine (MgFc53); or a substitution at position 243 with leucine, at position 305 with isoleucine, at position 378 with aspartic acid, at position 404 with serine, and at position 396 with leucine (MgFc54); or a substitution at position 255 with isoleucine, and at position 396 with leucine (MgFc55); or a substitution at position 370 with glutamic acid and at position 396 with leucine (MgFc59); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine (MgFc88); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine (MgFc88A); or a substitution at position 234 with leucine, at position 292 with proline, and at position 300 with leucine (MgFc155); or a substitution at position 243 with leucine, at position 292 with proline, and at position 300 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, and at position 396 with leucine; or a substitution at position 243 with leucine, and at position 292 with proline; or a substitution at position 243 with leucine; or a substitution at position 273 with phenylalanine.

[0212] In one specific embodiment, the invention encompasses a molecule comprising a variant Fc region wherein said variant Fc region comprises a substitution at position 396 with leucine, at position 270 with glutamic acid and at position 243 with leucine. In another specific embodiment the molecule further comprises one or more amino acid modification such as those disclosed herein.

[0213] In some embodiments, the invention encompasses molecules comprising a variant Fc region having an amino acid modification at one or more of the following positions: 119, 125, 132, 133, 141, 142, 147, 149, 162, 166, 185, 192, 202, 205, 210, 214, 217, 219, 215, 216, 217, 218, 219, 221, 222, 223, 224, 225, 227, 288, 229, 231, 232, 233, 235, 240, 241, 242, 243, 244, 246, 247, 248, 250, 251, 252, 253, 254, 255, 256, 258, 261, 262, 263, 268, 269, 270, 272, 273, 274, 275, 276, 279, 280, 281, 282, 284, 287, 288, 289, 290, 291, 292, 293, 295, 298, 300, 301, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 315, 316, 317, 318, 319, 320, 323, 326, 327, 328, 330, 333, 334, 335, 337, 339, 340, 343, 344, 345, 347, 348, 352, 353, 354, 355, 358, 359, 360, 361, 362, 365, 366, 367, 369, 370, 371, 372, 375, 377, 378, 379, 380, 381, 382, 383, 384, 385, 386, 387, 388, 389, 390, 392, 393, 394, 395, 396, 397, 398, 399, 400, 401, 402, 404, 406, 407, 408, 409, 410, 411, 412, 414, 415, 416417, 419, 420, 421, 422, 423, 424, 427, 428, 431, 433, 435, 436, 438, 440, 441, 442, 443, 446, 447. Preferably such mutations result in molecules that have an altered affinity for an FcγR and/or have an altered effector cell mediated function as determined using methods disclosed and exemplified herein and known to one skilled in the art.

[0214] The invention encompasses molecules comprising variant Fc regions consisting of or comprising any of the mutations listed in the table below in Table 5.

TABLE 5
EXEMPLARY MUTATIONS
	SINGLE SITE	DOUBLE SITE
	MUTANTS	MUTANTS
	K392R	Q347H, A339V
	N315I	S415I, L251F
	S132I	K290E, L142P
	P396L	G285E, P247H
	P396H	K409R, S166N
	A162V	E334A, K334A
	R292L	R292L. K334E
	T359N	K288N, A330S
	T366S	R255L, E318K
	V379L	F243L, E318K
	K288N	V279L, P395S
	A330S	K246T, Y319F
	F243L	F243I, V379L
	E318K	K288M, K334E
	V379M	K334E, E308D
	S219Y	E233D, K334E
	V282M	K246T, P396H
	D401V	H268D, E318D
	K222N	K246I, K334N
	K334I	K320E, K326E
	K334E	S375C, P396L
	I377F	K288N, K326N
	P247L	P247L, N421K
	F372Y	S298N, W381R
	K326E	R255Q, K326E
	H224L	V284A, F372L
	F275Y	T394M. V397M
	L398V	P247L, E389G
	K334N	K290T, G371D
	S400P	P247L, L398Q
	S407I	P247L, I377F
	F372Y	K326E, G385E
	T366N	S298N, S407R
	K414N	E258D, N384K
	M352L	F241L, E258G
	T225S	K370N, S440N
	I377N	K317N, F423-DELETED
	K248M	P227S, K290E
	R292G	K334E, E380D
	S298N	P291S, P353Q
	D270E	V240I, V281M
	E233G	P232S, S304G
	R292P	P247L, L406F
	V273	D399E, M428L
		L251F, F372L
		D399E, G402D
		D399E, M428L
		K392T, P396L
		H268N, P396L
		K326I, P396L
		H268D, P396L
		K210M, P396L
		L358P, P396L
		K334N, P396L
		V379M, P396L
		P227S, P396L
		P217S, P396L
		Q419H, P396L
		K370E, P396L
		L242F, P396L
		R255L, P396L
		V240A, P396L
		T250A, P396L
		P247S, P396L
		L410H, P396L
		Q419L, P396L
		V427A, P396L
		E258D, P396L
		N384K, P396L
		V323I, P396L
		P244H, P396L
		V305L, P396L
		S400F, P396L
		V303I, P396L
		A330V, Q419H
		V263Q, E272D
		K326E, A330T
		F243L, R292P
		F243L, P396L

[0215] In yet other embodiments, the invention encompasses molecules comprising variant Fc regions having more than two amino acid modifications. A non-limiting example of such variants is listed in the table below (Table 6). The invention encompasses mutations listed in Table 6 which further comprise one or more amino acid modifications such as those disclosed herein.

TABLE 6
EXEMPLARY COMBINATION VARIANTS
	D399E, R292L, V185M
	R301C, M252L, S192T
	P291S, K288E, H268L, A141V
	S383N, N384K, T256N, V262L, K218E, R214I, K205E,
	F149Y, K133M
	S408I, V215I, V125L
	G385E, P247H
	V348M, K334N, F275I, Y202M, K147T
	H310Y, T289A, Y407V, E258D
	R292L, P396L, T359N
	F275I, K334N, V348M
	F243L, R255L, E318K
	K334E, T359N, T366S
	T256S, V305I, K334E, N390S
	T335N, K370E, A378V, T394M, S424L
	K334E, T359N, T366S, Q386R
	K288N, A330S, P396L
	P244H, L358M, V379M, N384K, V397M
	P217S, A378V, S408R
	P247L, I253N, K334N
	D312E, K327N, I378S
	D280E, S354F, A431D, L441I
	K218R, G281D, G385R
	P247L, A330T, S440G
	T355N, P387S, H435Q
	P247L, A431V, S442F
	P343S, P353L, S375I, S383N
	E216D, E345K, S375I
	K288N, A330S, P396L
	K222N, T335N, K370E, A378V, T394M
	G316D, A378V, D399E
	N315I, V379M, T394M
	K326Q, K334E, T359N, T366S
	A378V, N390I, V422I
	V282E, V369I, L406F
	V397M, T411A, S415N
	T223I, T256S, L406F
	L235P, V382M, S304G, V305I, V323I
	P247L, W313R, E388G
	D221Y, M252I, A330G, A339T, T359N, V422I, H433L
	F243I, V379L, G420V
	A231V, Q386H, V412M
	T215P, K274N, A287G, K334N, L365V, P396L
	P244A, K326I, C367R, S375I, K447T
	R301H, K340E, D399E
	C229Y, A287T, V379M, P396L, L443V
	E269K, K290N, Q311R, H433Y
	E216D, K334R, S375I
	T335N, P387S, H435Q
	K246I, Q362H, K370E
	K334E, E380D, G446V
	V303I, V369F, M428L
	K246E, V284M, V308A
	E293V, Q295E, A327T
	Y319F, P352L, P396L
	D221E, D270E, V308A, Q311H, P396L, G402D
	K290T, N390I, P396L
	K288R, T307A, K344E, P396L
	V273I, K326E, L328I, P396L
	K326I, S408N, P396L
	K261N, K210M, P396L
	F243L, V305I, A378D, F404S, P396L
	K290E, V369A, T393A, P396L
	K210N, K222I, K320M, P396L
	P217S, V305I, I309L, N390H, P396L
	K246N, Q419R, P396L
	P217A, T359A, P396L
	V215I, K290V, P396L
	F275L, Q362H, N384K, P396L
	A330V, H433Q, V427M
	V263Q, E272D, Q419H
	N276Y, T393N, W417R
	V282L, A330V, H433Y, T436R
	V284M, S298N, K334E, R355W
	A330V, G427M, K438R
	S219T, T225K, D270E, K360R
	K222E, V263Q, S298N
	E233G, P247S, L306P
	S219T, T225K, D270E
	S254T, A330V, N361D, P243L
	V284M, S298N, K334E, R355W R416T
	D270E, G316D, R416G
	K392T, P396L, D270E
	R255L, P396L, D270E
	V240A, P396L, D270E
	Q419H, P396L, D270E
	K370E, P396L, D270E
	P247L, N421K, D270E
	R292P, V305I
	R292P, V305I, F243L
	V284M, R292L, K370N
	R292P, V305I, P396L
	F243L, R292P, Y300L,
	F243L, R292P, P396L
	F243L, R292P, V305L
	F243L, Y300L, V305I, P396L
	F243L, R292P, V305I, P396L
	F243L, R292P, Y300L, P396L
	F243I, R292P, Y300L, V305I, P396L

[0216] In some embodiments, the molecules, preferably the immunoglobulins of the invention further comprise one or more glycosylation sites, so that one or more carbohydrate moieties are covalently attached to the molecule. Preferably, the antibodies of the invention with one or more glycosylation sites and/or one or more modifications in the Fc region have an enhanced antibody mediated effector function, e.g., enhanced ADCC activity. In some embodiments, the invention further comprises antibodies comprising one or more modifications of amino acids that are directly or indirectly known to interact with a carbohydrate moiety of the antibody, including but not limited to amino acids at positions 241, 243, 244, 245, 245, 249, 256, 258, 260, 262, 264, 265, 296, 299, and 301. Amino acids that directly or indirectly interact with a carbohydrate moiety of an antibody are known in the art, see, e.g., Jefferis et al., 1995 Immunology Letters, 44: 111-7, which is incorporated herein by reference in its entirety.

[0217] The invention encompasses antibodies that have been modified by introducing one or more glycosylation sites into one or more sites of the antibodies, preferably without altering the functionality of the antibody, e.g., binding activity to FcγR. Glycosylation sites may be introduced into the variable and/or constant region of the antibodies of the invention. As used herein, “glycosylation sites” include any specific amino acid sequence in an antibody to which an oligosaccharide (i.e., carbohydrates containing two or more simple sugars linked together) will specifically and covalently attach. Oligosaccharide side chains are typically linked to the backbone of an antibody via either N- or O-linkages. N-linked glycosylation refers to the attachment of an oligosaccharide moiety to the side chain of an asparagine residue. O-linked glycosylation refers to the attachment of an oligosaccharide moiety to a hydroxyamino acid, e.g., serine, threonine. The antibodies of the invention may comprise one or more glycosylation sites, including N-linked and O-linked glycosylation sites. Any glycosylation site for N-linked or O-linked glycosylation known in the art may be used in accordance with the instant invention. An exemplary N-linked glycosylation site that is useful in accordance with the methods of the present invention, is the amino acid sequence: Asn-X-Thr/Ser, wherein X may be any amino acid and Thr/Ser indicates a threonine or a serine. Such a site or sites may be introduced into an antibody of the invention using methods well known in the art to which this invention pertains. See, for example, “In Vitro Mutagenesis,” Recombinant DNA: A Short Course, J. D. Watson, et al. W.H. Freeman and Company, New York, 1983, chapter 8, pp. 106-116, which is incorporated herein by reference in its entirety. An exemplary method for introducing a glycosylation site into an antibody of the invention may comprise: modifying or mutating an amino acid sequence of the antibody so that the desired Asn-X-Thr/Ser sequence is obtained.

[0218] In some embodiments, the invention encompasses methods of modifying the carbohydrate content of an antibody of the invention by adding or deleting a glycosylation site. Methods for modifying the carbohydrate content of antibodies are well known in the art and encompassed within the invention, see, e.g., U.S. Pat. No. 6,218,149; EP 0 359 096 B1; U.S. Publication No. US 2002/0028486; WO 03/035835; U.S. Publication No. 2003/0115614; U.S. Pat. No. 6,218,149; U.S. Pat. No. 6,472,511; all of which are incorporated herein by reference in their entirety. In other embodiments, the invention encompasses methods of modifying the carbohydrate content of an antibody of the invention by deleting one or more endogenous carbohydrate moieties of the antibody. In a specific embodiment, the invention encompasses shifting the glycosylation site of the Fc region of an antibody, by modifying positions adjacent to 297. In a specific embodiment, the invention encompasses modifying position 296 so that position 296 and not position 297 is glycosylated.

[0219] 5.1 Polypeptides and Antibodies with Variant Fc Regions

[0220] The present invention is based, in part, on the identification of mutant human IgG1 heavy chain Fc regions, with altered affinities for different FcγR receptors, using a yeast display system. Accordingly, the invention relates to molecules, preferably polypeptides, and more preferably immunoglobulins (e.g., antibodies), comprising a variant Fc region, having one or more amino acid modifications (e.g., substitutions, but also including insertions or deletions) in one or more regions, which modifications alter the affinity of the variant Fc region for an FcγR.

[0221] It will be appreciated by one skilled in the art that aside from amino acid substitutions, the present invention contemplates other modifications of the Fc region amino acid sequence in order to generate an Fc region variant with one or more altered properties, e.g., altered effector function. The invention contemplates deletion of one or more amino acid residues of the Fc region in order to reduce binding to an FcγR. Preferably, no more than 5, no more than 10, no more than 20, no more than 30, no more than 50 Fc region residues will be deleted according to this embodiment of the invention. The Fc region herein comprising one or more amino acid deletions will preferably retain at least about 80%, and preferably at least about 90%, and most preferably at least about 95%, of the wild type Fc region. In some embodiments, one or more properties of the molecules are maintained such as for example, non-immunogenicity, FcγRIIIA binding, FcγRIIA binding, or a combination of these properties.

[0222] In alternate embodiments, the invention encompasses amino acid insertion to generate the Fc region variants, which variants have altered properties including altered effector function. In one specific embodiment, the invention encompasses introducing at least one amino acid residue, for example one to two amino acid residues and preferably no more than 10 amino acid residues adjacent to one or more of the Fc region positions identified herein. In alternate embodiments, the invention further encompasses introducing at least one amino acid residue, for example one to two amino acid residues and preferably no more than 10 amino acid residues adjacent to one or more of the Fc region positions known in the art as impacting FcγR interaction and/or binding.

[0223] The invention further encompasses incorporation of unnatural amino acids to generate the Fc variants of the invention. Such methods are known to those skilled in the art such as those using the natural biosynthetic machinery to allow incorporation of unnatural amino acids into proteins, see, e.g., Wang et al., 2002 Chem. Comm. 1:1-11; Wang et al., 2001, Science, 292: 498-500; van Hest et al., 2001. Chem. Comm. 19: 1897-1904, each of which is incorporated herein by reference in its entirety. Alternative strategies focus on the enzymes responsible for the biosynthesis of amino acyl-tRNA, see, e.g., Tang et al., 2001, J. Am. Chem. 123(44): 11089-11090; Kiick et al., 2001, FEBS Lett. 505(3): 465; each of which is incorporated herein by reference in its entirety.

[0224] The affinities and binding properties of the molecules of the invention for an FcγR are initially determined using in vitro assays (biochemical or immunological based assays) known in the art for determining Fc-FcγR interactions, i.e., specific binding of an Fc region to an FcγR including but not limited to ELISA assay, surface plasmon resonance assay, immunoprecipitation assays (See Section 5.2.5.1). Preferably, the binding properties of the molecules of the invention are also characterized by in vitro functional assays for determining one or more FcγR mediator effector cell functions (See Section 5.2.7). In most preferred embodiments, the molecules of the invention have similar binding properties in in vivo models (such as those described and disclosed herein) as those in in vitro based assays However, the present invention does not exclude molecules of the invention that do not exhibit the desired phenotype in in vitro based assays but do exhibit the desired phenotype in vivo. A representative flow chart of the screening and characterization of molecules of the invention is described in FIG. 35.

[0225] The invention encompasses molecules comprising a variant Fc region that binds with a greater affinity to one or more FcγRs. Such molecules preferably mediate effector function more effectively as discussed infra. In other embodiments, the invention encompasses molecules comprising a variant Fc region that bind with a weaker affinity to one or more FcγRs. Reduction or elimination of effector function is desirable in certain cases for example in the case of antibodies whose mechanism of action involves blocking or antagonism but not killing of the cells bearing a target antigen. Reduction or elimination of effector function would be desirable in cases of autoimmune disease where one would block FcγR activating receptors in effector cells (This type of function would be present in the host cells). In general increased effector function would be directed to tumor and foreign cells.

[0226] The Fc variants of the present invention may be combined with other Fc modifications, including but not limited to modifications that alter effector function. The invention encompasses combining an Fc variant of the invention with other Fc modifications to provide additive, synergistic, or novel properties in antibodies or Fc fusions. Preferably the Fc variants of the invention enhance the phenotype of the modification with which they are combined. For example, if an Fc variant of the invention is combined with a mutant known to bind FcγRIIIA with a higher affinity than a comparable molecule comprising a wild type Fc region; the combination with a mutant of the invention results in a greater fold enhancement in FcγRIIIA affinity.

[0227] In one embodiment, the Fc variants of the present invention may be combined with other known Fc variants such as those disclosed in Duncan et al, 1988, Nature 332:563-564; Lund et al., 1991, J. Immunol 147:2657-2662; Lund et al, 1992, Mol Immunol 29:53-59; Alegre et al, 1994, Transplantation 57:1537-1543; Hutchins et al., 1995, Proc Natl. Acad Sci USA 92:11980-11984; Jefferis et al, 1995, Immunol Lett. 44:111-117; Lund et al., 1995, Faseb J 9:115-119; Jefferis et al, 1996, Immunol Lett 54:101-104; Lund et al, 1996, J Immunol 157:49634969; Armour et al., 1999, Eur J Immunol 29:2613-2624; Idusogie et al, 2000, J Immunol 164:41784184; Reddy et al, 2000, J Immunol 164:1925-1933; Xu et al., 2000, Cell Immunol 200:16-26; Idusogie et al, 2001, J Immunol 166:2571-2575; Shields et al., 2001, J Biol Chem 276:6591-6604; Jefferis et al, 2002, Immunol Lett 82:57-65; Presta et al., 2002, Biochem Soc Trans 30:487-490); U.S. Pat. No. 5,624,821; U.S. Pat. No. 5,885,573; U.S. Pat. No. 6,194,551; PCT WO 00/42072; PCT WO 99/58572; each of which is incorporated herein by reference in its entirety.

[0228] In some embodiments, the Fc variants of the present invention are incorporated into an antibody or Fc fusion that comprises one or more engineered glycoforms, i.e., a carbohydrate composition that is covalently attached to a molecule comprising an Fc region, wherein said carbohydrate composition differs chemically from that of a parent molecule comprising an Fc region. Engineered glycoforms may be useful for a variety of purposes, including but not limited to enhancing or reducing effector function. Engineered glycoforms may be generated by any method known to one skilled in the art, for example by using engineered or variant expression strains, by co-expression with one or more enzymes, for example DI N-acetylglucosaminyltransferase III (GnTI11), by expressing a molecule comprising an Fc region in various organisms or cell lines from various organisms, or by modifying carbohydrate(s) after the molecule comprising Fc region has been expressed. Methods for generating engineered glycoforms are known in the art, and include but are not limited to those described in Umana et al, 1999, Nat. Biotechnol 17:176-180; Davies et al., 20017 Biotechnol Bioeng 74:288-294; Shields et al, 2002, J Biol Chem 277:26733-26740; Shinkawa et al., 2003, J Biol Chem 278:3466-3473) U.S. Pat. No. 6,602,684; U.S. Ser. No. 10/277,370; U.S. Ser. No. 10/113,929; PCT WO 00/61739A1; PCT WO 01/292246A1; PCT WO 02/311140A1; PCT WO 02/30954A1; Potillegent™ technology (Biowa, Inc. Princeton, N.J.); GlycoMAb™ glycosylation engineering technology (GLYCART biotechnology AG, Zurich, Switzerland); each of which is incorporated herein by reference in its entirety. See, e.g., WO 00061739; EA01229125; US 20030115614; Okazaki et al., 2004, JMB, 336: 1239-49 each of which is incorporated herein by reference in its entirety.

[0229] The Fc variants of the present invention may be optimized for a variety of properties. Properties that may be optimized include but are not limited to enhanced or reduced affinity for an FcγR, enhanced or reduced effector function. In a preferred embodiment, the Fc variants of the present invention are optimized to possess enhanced affinity for a human activating FcγR, preferably FcγR, FcγRIIA, FcγRIIc, FcγRIIIA, and FcγRIIIB, most preferably FcγRIIIA. In an alternate preferred embodiment, the Fc variants are optimized to possess reduced affinity for the human inhibitory receptor FcγRIIB. These preferred embodiments are anticipated to provide antibodies and Fc fusions with enhanced therapeutic properties in humans, for example enhanced effector function and greater anti-cancer potency as described and exemplified herein. These preferred embodiments are anticipated to provide antibodies and Fc fusions with enhanced tumor elimination in mouse xenograft tumor models.

[0230] In an alternate embodiment the Fc variants of the present invention are optimized to have reduced affinity for a human FcγR, including but not limited to FcγRI, FcγRIIA, FcγRIIB, FcγRIIc, FcγRIIIA, and FcγRIIIB. These embodiments are anticipated to provide antibodies and Fc fusions with enhanced therapeutic properties in humans, for example reduced effector function and reduced toxicity.

[0231] In alternate embodiments the Fc variants of the present invention possess enhanced or reduced affinity for FcγRs from non-human organisms, including but not limited to mice, rats, rabbits, and monkeys. Fc variants that are optimized for binding to a non-human FcγR may find use in experimentation. For example, mouse models are available for a variety of diseases that enable testing of properties such as efficacy, toxicity, and pharmacokinetics for a given drug candidate. As is known in the art, cancer cells can be grafted or injected into mice to mimic a human cancer, a process referred to as xenografting. Testing of antibodies or Fc fusions that comprise Fc variants that are optimized for one or more mouse FcγRs, may provide valuable information with regard to the efficacy of the antibody or Fc fusion, its mechanism of action, and the like.

[0232] While it is preferred to alter binding to an FcγR, the instant invention further contemplates Fc variants with altered binding affinity to the neonatal receptor (FcRn). Although not intending to be bound by a particular mechanism of action, Fc region variants with improved affinity for FcRn are anticipated to have longer serum half-lives, and such molecules will have useful applications in methods of treating mammals where long half-life of the administered polypeptide is desired, e.g., to treat a chronic disease or disorder. Although not intending to be bound by a particular mechanism of action, Fc region variants with decreased FcRn binding affinity, on the contrary, are expected to have shorter half-lives, and such molecules may, for example, be administered to a mammal where a shortened circulation time may be advantageous, e.g., for in vivo diagnostic imaging or for polypeptides which have toxic side effects when left circulating in the blood stream for extended periods. Fc region variants with decreased FcRn binding affinity are anticipated to be less likely to cross the placenta, and thus may be utilized in the treatment of diseases or disorders in pregnant women.

[0233] In other embodiments, these variants may be combined with other known Fc modifications with altered FcRn affinity such as those disclosed in International Publication Nos. WO 98/23289; and WO 97/34631; and U.S. Pat. No. 6,277,375, each of which is incorporated herein by reference in its entirety.

[0234] The invention encompasses any other method known in the art for generating antibodies having an increased half-life in vivo, for example, by introducing one or more amino acid modifications (i.e., substitutions, insertions or deletions) into an IgG constant domain, or FcRn binding fragment thereof (preferably a Fc or hinge-Fc domain fragment). See, e.g., International Publication Nos. WO 98/23289; and WO 97/34631; and U.S. Pat. No. 6,277,375, each of which is incorporated herein by reference in its entirety to be used in combination with the Fc variants of the invention. Further, antibodies of the invention can be conjugated to albumin in order to make the antibody or antibody fragment more stable in vivo or have a longer half-life in vivo. The techniques well-known in the art, see, e.g., International Publication Nos. WO 93/15199, WO 93/15200, and WO 01/77137, and European Patent No. EP 413,622, all of which are incorporated herein by reference in their entirety.

[0235] The variant(s) described herein may be subjected to further modifications, often times depending on the intended use of the variant. Such modifications may involve further alteration of the amino acid sequence (substitution, insertion and/or deletion of amino acid residues), fusion to heterologous polypeptide(s) and/or covalent modifications. Such further modifications may be made prior to, simultaneously with, or following, the amino acid modification(s) disclosed herein which results in altered properties such as an alteration of Fc receptor binding and/or ADCC activity.

[0236] Alternatively or additionally, the invention encompasses combining the amino acid modifications disclosed herein with one or more further amino acid modifications that alter C1q binding and/or complement dependent cytoxicity function of the Fc region as determined in vitro and/or in vivo. Preferably, the starting molecule of particular interest herein is usually one that binds to C1q and displays complement dependent cytotoxicity (CDC). The further amino acid substitutions described herein will generally serve to alter the ability of the starting molecule to bind to C1q and/or modify its complement dependent cytotoxicity function, e.g., to reduce and preferably abolish these effector functions. In other embodiments molecules comprising substitutions at one or more of the described positions with improved C1q binding and/or complement dependent cytotoxicity (CDC) function are contemplated herein. For example, the starting molecule may be unable to bind C1q and/or mediate CDC and may be modified according to the teachings herein such that it acquires these further effector functions. Moreover, molecules with preexisting C1q binding activity, optionally further having the ability to mediate CDC may be modified such that one or both of these activities are altered, e.g., enhanced. In some embodiments, the invention encompasses variant Fc regions with altered CDC activity without any alteration in C1q binding. In yet other embodiments, the invention encompasses variant Fc regions with altered CDC activity and altered C1q binding.

[0237] To generate an Fc region with altered C1q binding and/or complement dependent cytotoxicity (CDC) function, the amino acid positions to be modified are generally selected from positions 270, 322, 326, 327, 329, 331, 333, and 334, where the numbering of the residues in an IgG heavy chain is that of the EU index as in Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (199). These amino acid modifications may be combined with one or more Fc modifications disclosed herein to provide a synergistic or additive effect on C1q binding and/or CDC activity. In other embodiments, the invention encompasses Fc variants with altered C1q binding and/or complement dependent cytotoxicity (CDC) function comprising an amino acid substitution at position 396 with leucine and at position 255 with leucine; or an amino acid substitution at position 396 with leucine and at position 419 with histidine; an amino acid substitution at position 396 with leucine and at position 370 with glutamic acid; an amino acid substitution at position 396 with leucine and at position 240 with alanine; an amino acid substitution at position 396 with leucine and at position 392 with threonine; an amino acid substitution at position 247 with leucine and at position 421 with lysine. The invention encompasses any known modification of the Fc region which alters C1q binding and/or complement dependent cytotoxicity (CDC) function such as those disclosed in Idusogie et al., 2001, J. Immunol. 166(4) 2571-5; Idusogie et al., J. Immunol. 2000 164(8): 4178-4184; each of which is incorporated herein by reference in its entirety.

[0238] As disclosed above, the invention encompasses an Fc region with altered effector function, e.g., modified C1q binding and/or FcR binding and thereby altered CDC activity and/or ADCC activity. In specific embodiments, the invention encompasses variant Fc regions with improved C1q binding and improved FcγRIII binding; e.g. having both improved ADCC activity and improved CDC activity. In alternative embodiments, the invention encompasses a variant Fc region with reduced CDC activity and/or reduced ADCC activity. In other embodiments, one may increase only one of these activities, and optionally also reduce the other activity, e.g. to generate an Fc region variant with improved ADCC activity, but reduced CDC activity and vice versa.

[0239] A. Mutants with Enhanced Altered Affinities for FcγRIIIA and/or FcγRIIA

[0240] The invention encompasses molecules comprising a variant Fc region, having one or more amino acid modifications (e.g., substitutions) in one or more regions, wherein such modifications alter the affinity of the variant Fc region for an activating FcγR. In some embodiments, molecules of the invention comprise a variant Fc region, having one or more amino acid modifications (e.g., substitutions) in one or more regions, which modifications increase the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA by at least 2-fold, relative to a comparable molecule comprising a wild-type Fc region. In another specific embodiment, molecules of the invention comprise a variant Fc region, having one or more amino acid modifications (e.g., substitutions) in one or more regions, which modifications increase the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA by greater than 2 fold, relative to a comparable molecule comprising a wild-type Fc region. In other embodiments of the invention the one or more amino acid modifications increase the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA by at least 3-fold, 4-fold, 5-fold, 6-fold, 8-fold, or 10-fold relative to a comparable molecule comprising a wild-type Fc region. In yet other embodiments of the invention the one or more amino acid modifications decrease the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA by at least 3-fold, 4-fold, 5-fold, 6-fold, 8-fold, or 10-fold relative to a comparable molecule comprising a wild-type Fc region. Such fold increases are preferably determined by an ELISA or surface plasmon resonance assays. In a specific embodiment, the one or more amino acid modifications do not include or are not solely a substitution at any one of positions 329, 331, or 322 with any amino acid. In certain embodiments, the one or more amino acid modifications do not include or are not solely a substitution with any one of alanine at positions 256, 290, 298, 312, 333, 334, 359, 360, or 430; with lysine at position 330; with threonine at position 339; with methionine at position 320; with serine, asparagine, aspartic acid, or glutamic acid at position 326 with glutamine, glutamic acid, methionine, histidine, valine, or leucine at position 334. In another specific embodiment, the one or more amino acid modifications do not include or are not solely a substitution at any of positions 280, 290, 300, 294, or 295. In another more specific embodiment, the one or more amino acid modifications do not include or are not solely a substitution at position 300 with leucine or isoleucine; at position 295 with lysine; at position 294 with asparagine; at position 298 with valine; aspartic acid proline, aspargine, or valine; at position 280 with histidine, glutamine or tyrosine; at position 290 with serine, glycine, theonine or tyrosine.

[0241] In another specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIA with a greater affinity than a comparable molecule comprising the wild-type Fc region binds FcγRIIA, provided that said variant Fc region does not have an alanine at any of positions 256, 290, 326, 255, 258, 267, 272, 276, 280, 283, 285, 286, 331, 337, 268, 272, or 430; an asparagine at position 268; a glutamine at position 272; a glutamine, serine, or aspartic acid at position 286; a serine at position 290; a methionine, glutamine, glutamic acid, or arginine at position 320; a glutamic acid at position 322; a serine, glutamic acid, or aspartic acid at position 326; a lysine at position 330; a glutamine at position 335; or a methionine at position 301. In a specific embodiment, molecules of the invention comprise a variant Fc region, having one or more amino acid modifications (e.g., substitutions) in one or more regions, which modifications increase the affinity of the variant Fc region for FcγRIIA by at least 2-fold, relative to a comparable molecule comprising a wild-type Fc region. In another specific embodiment, molecules of the invention comprise a variant Fc region, having one or more amino acid modifications (e.g., substitutions) in one or more regions, which modifications increase the affinity of the variant Fc region for FcγRIIA by greater than 2 fold, relative to a comparable molecule comprising a wild-type Fc region. In other embodiments of the invention the one or more amino acid modifications increase the affinity of the variant Fc region for FcγRIIA by at least 3-fold, 4-fold, 5-fold, 6-fold, 8-fold, or 10-fold relative to a comparable molecule comprising a wild-type Fc region

[0242] In a specific embodiment, the invention encompasses molecules, preferably polypeptides, and more preferably immunoglobulins (e.g., antibodies), comprising a variant Fc region, having one or more amino acid modifications (e.g., substitutions but also include insertions or deletions), which modifications increase the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA by at least 65%, at least 70%, at least 75%, at least 85%, at least 90%, at least 95%, at least 99%, at least 100%, at least 150%, and at least 200%, relative to a comparable molecule comprising a wild-type Fc region.

[0243] In a specific embodiment, the one or more amino acid modifications which increase the affinity of the variant Fc region for one or more activating FcγRs comprise a substitution at position 347 with histidine, and at position 339 with valine; or a substitution at position 425 with isoleucine and at position 215 with phenylalanine; or a substitution at position 408 with isoleucine, at position 215 with isoleucine, and at position 125 with leucine; or a substitution at position 385 with glutamic acid and at position 247 with histidine; or a substitution at position 348 with methionine, at position 334 with asparagine, at position 275 with isoleucine, at position 202 with methionine, and at position 147 with threonine; or a substitution at position 275 with isoleucine, at position 334 with asparagine, and at position 348 with methionine; or a substitution at position 279 with leucine and at position 395 with serine; or a substitution at position 246 with threonine and at position 319 with phenylalanine; or a substitution at position 243 with isoleucine and at position 379 with leucine; or a substitution at position 243 with leucine, at position 255 with leucine and at position 318 with lysine; or a substitution at position 334 with glutamic acid, at position 359 with asparagine, and at position 366 with serine; or a substitution at position 288 with methionine and at position 334 with glutamic acid; or a substitution at position 334 with glutamic acid and at position 380 with aspartic acid; or a substitution at position 256 with serine, at position 305 with isoleucine, at position 334 with glutamic acid and at position 390 with serine; or a substitution at position 335 with asparagine, at position 370 with glutamic acid, at position 378 with valine, at position 394 with methionine, and at position 424 with leucine; or a substitution at position 233 with aspartic acid and at position 334 with glutamic acid; or a substitution at position 334 with glutamic acid, at position 359 with asparagine, at position 366 with serine, and at position 386 with arginine; or a substitution at position 246 with threonine and at position 396 with histidine; or a substitution at position 268 with aspartic acid and at position 318 with aspartic acid; or a substitution at position 288 with asparagine, at position 330 with serine, and at position 396 with leucine; or a substitution at position 244 with histidine, at position 358 with methionine, at position 379 with methionine, at position 384 with lysine and at position 397 with methionine; or a substitution at position 217 with serine, at position 378 with valine, and at position 408 with arginine; or a substitution at position 247 with leucine, at position 253 with asparagine, and at position 334 with asparagine; or a substitution at position 246 with isoleucine, and at position 334 with asparagine; or a substitution at position 320 with glutamic acid and at position 326 with glutamic acid; or a substitution at position 375 with cysteine and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine; or a substitution at position 234 with leucine, at position 292 with proline, and at position 300 with leucine; or a substitution at position 234 with leucine, at position 292 with proline, and at position 396 with leucine; or a substitution at position 234 with leucine, at position 292 with proline, and at position 305 with isoleucine; or a substitution at position 234 with leucine and at position 292 with proline; or a substitution at position 234 with leucine. Examples of other amino acid substitutions that results in an enhanced affinity for FcγRIIIA in vitro are disclosed below and summarized in Table 5.

[0244] The invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises a substitution at position 243 with isoleucine and at position 379 with leucine, such that said molecule binds FcγRIIIA with about a 1.5 fold higher affinity than a comparable molecule comprising the wild type Fc region binds FcγRIIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises a substitution at position 288 with asparagine, at position 330 with serine, and at position 396 with leucine, such that said molecule binds FcγRIIIA with about a 5 fold higher affinity than a comparable molecule comprising the wild type Fc region binds FcγRIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises a substitution at position 243 with leucine and at position 255 with leucine such that said molecule binds FcγRIIIA with about a 1 fold higher affinity than a comparable molecule comprising the wild type Fc region binds FcγRIIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises a substitution at position 334 with glutamic acid, at position 359 with asparagine, and at position 366 with serine, such that said molecule binds FcγRIIIA with about a 1.5 fold higher affinity than a comparable molecule comprising the wild type Fc region binds FcγRIIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises a substitution at position 288 with methionine and at position 334 with glutamic acid, such that said molecule binds FcγRIIIA with about a 3 fold higher affinity than a comparable molecule comprising the wild type Fc region binds FcγRIIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises a substitution at position 316 with aspartic acid, at position 378 with valine, and at position 399 with glutamic acid, such that said molecule binds FcγRIIIA with about a 1.5 fold higher affinity than a comparable molecule comprising the wild type Fc region binds FcγRIIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises a substitution at position 315 with isoleucine, at position 379 with methionine, and at position 399 with glutamic acid, such that said molecule binds FcγRIIIA with about a 1 fold higher affinity than a comparable molecule comprising the wild type Fc region binds FcγRIIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises a substitution at position 243 with isoleucine, at position 379 with leucine, and at position 420 with valine, such that said molecule binds FcγRIIIA with about a 2.5 fold higher affinity than a comparable molecule comprising the wild type Fc region binds FcγRIIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises a substitution at position 247 with leucine, and at position 421 with lysine, such that said molecule binds FcγRIIIA with about a 3 fold higher affinity than a comparable molecule comprising the wild type Fc region binds FcγRIIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises a substitution at position 392 with threonine and at position 396 with leucine such that said molecule binds FcγRIIIA with about a 4.5 fold higher affinity than a comparable molecule comprising the wild type Fc region binds FcγRIIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises a substitution at position 293 with valine, at position 295 with glutamic acid, and at position 327 with threonine, such that said molecule binds FcγRIIIA with about a 1.5 fold higher affinity than a comparable molecule comprising the wild type Fc region binds FcγRIIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises a substitution at position 268 with asparagine and at position 396 with leucine, such that said molecule binds FcγRIIIA with about a 2 fold higher affinity than a comparable molecule comprising the wild type Fc region binds FcγRIIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fc region, wherein said variant Fc region comprises a substitution at position 319 with phenylalanine, at position 352 with leucine, and at position 396 with leucine, such that said molecule binds FcγRIIIA with about a 2 fold higher affinity than a comparable molecule comprising the wild type Fc region binds FcγRIIIA, as determined by an ELISA assay.

[0245] In a specific embodiment, the invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 396 with histidine. In a specific embodiment, the invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 248 with methionine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a similar affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 392 with arginine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a similar affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 315 with isoleucine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a similar affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 132 with isoleucine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a similar affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 162 with valine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 396 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 379 with methionine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 219 with tyrosine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 282 with methionine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 401 with valine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 222 with asparagine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 334 with glutamic acid. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 377 with phenylalaine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 334 with isoleucine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 247 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 326 with glutamic acid. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 372 with tyrosine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 224 with leucine.

[0246] The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 275 with tyrosine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 398 with valine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 334 with asparagine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 400 with proline. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 407 with isoleucine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 372 with tyrosine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a similar affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 366 with asparagine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a reduced affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 414 with asparagine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a reduced affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 225 with serine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a reduced affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 377 with asparagine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 243 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 292 with proline. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 300 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 305 with isoleucine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 396 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fc region, wherein said at least one amino acid modification comprises substitution at position 273 with phenylalanine.

[0247] In a specific embodiment, the invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with about a 2 fold greater affinity than a comparable polypeptide comprising the wild-type Fc region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 379 with methionine. In another specific embodiment, the invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIIA with about a 1.5 fold greater affinity than a comparable polypeptide comprising the wild-type Fc region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 248 with methionine.

[0248] In some embodiments, the molecules of the invention have an altered affinity for FcγRIIIA and/or FcγRIIA as determined using in vitro assays (biochemical or immunological based assays) known in the art for determining Fc-FcγR interactions, i.e., specific binding of an Fc region to an FcγR including but not limited to ELISA assay, surface plasmon resonance assay, immunoprecipitation assays (See Section 5.2.5.1). Preferably, the binding properties of these molecules with altered affinities for activating FcγR receptors are also correlated to their activity as determined by in vitro functional assays for determining one or more FcγR mediator effector cell functions (See Section 5.2.7), e.g., molecules with variant Fc regions with enhanced affinity for FcγRIIIA have an enhanced ADCC activity. In most preferred embodiments, the molecules of the invention that have an altered binding property for an activating Fc receptor, e.g., FcγRIIIA in an in vitro assay also have an altered binding property in in vivo models (such as those described and disclosed herein). However, the present invention does not exclude molecules of the invention that do not exhibit an altered FcγR binding in in vitro based assays but do exhibit the desired phenotype in vivo.

[0249] B. Mutants with Enhanced Affinity for FcγRIIIA and Reduced or No Affinity for FcγRIIB

[0250] In a specific embodiment, the molecules of the invention comprise a variant Fc region, having one or more amino acid modifications (i.e., substitutions) in one or more regions, which one or more modifications increase the affinity of the variant Fc region for FcγRIIIA and decreases the affinity of the variant Fc region for FcγRIIB, relative to a comparable molecule comprising a wild-type Fc region which binds FcγRIIIA and FcγRIIB with wild-type affinity. In a certain embodiment, the one or more amino acid modifications do not include or are not solely a substitution with alanine at any of positions 256, 298, 333, 334, 280, 290, 294, 298, or 296; or a substitution at position 298 with asparagine, valine, aspartic acid, or proline; or a substitution 290 with serine. In certain amino embodiments, the one or more amino acid modifications increases the affinity of the variant Fc region for FcγRIIIA by at least 65%, at least 70%, at least 75%, at least 85%, at least 90%, at least 95%, at least 99%, at least 100%, at least 200%, at least 300%, at least 400% and decreases the affinity of the variant Fc region for FcγRIIB by at least 65%, at least 70%, at least 75%, at least 85%, at least 90%, at least 95%, at least 99%, at least 100%, at least 200%, at least 300%, at least 400%.

[0251] In a specific embodiment, the molecule of the invention comprising a variant Fc region with an enhanced affinity for FcγRIIIA and a lowered affinity or no affinity for FcγRIIB, as determined based on an ELISA assay and/or an ADCC based assay using ch-4-4-20 antibody, or a surface plasmon resonance assay using a chimeric 4D5 antibody, carrying the variant Fc region comprises a substitution at position 275 with isoleucine, at position 334 with asparagine, and at position 348 with methionine; or a substitution at position 279 with leucine and at position 395 with serine; or a substitution at position 246 with threonine and at position 319 with phenylalanine; or a substitution at position 243 with leucine, at position 255 with leucine, and at position 318 with lysine; or a substitution at position 334 with glutamic acid, at position 359 with asparagine and at position 366 with serine; or a substitution at position 334 with glutamic acid and at position 380 with aspartic acid; or a substitution at position 256 with serine, at position 305 with isoleucine, at position 334 with glutamic acid, and at position 390 with serine; or a substitution at position 335 with asparagine, at position 370 with glutamic acid, at position 378 with valine, at position 394 with methionine and at position 424 with leucine; or a substitution at position 233 with aspartic acid and at position 334 with glutamic acid; or a substitution at position 334 with glutamic acid, at position 359 with asparagine, at position 366 with serine and at position 386 with arginine; or a substitution at position 312 with glutamic acid, at position 327 with asparagine, and at position 378 with serine; or a substitution at position 288 with asparagine and at position 326 with asparagine; or a substitution at position 247 with leucine and at position 421 with lysine; or a substitution at position 298 with asparagine and at position 381 with arginine; or a substitution at position 280 with glutamic acid, at position 354 with phenylalanine, at position 431 with aspartic acid, and at position 441 with isoleucine; or a substitution at position 255 with glutamine and at position 326 with glutamic acid; or a substitution at position 218 with arginine, at position 281 with aspartic acid and at position 385 with arginine; or a substitution at position 247 with leucine, at position 330 with threonine and at position 440 with glycine; or a substitution at position 284 with alanine and at position 372 with leucine; or a substitution at position 335 with asparagine, as position 387 with serine and at position 435 with glutamine; or a substitution at position 247 with leucine, at position 431 with valine and at position 442 with phenylalanine; or a substitution at position 243 with leucine, at position 292 with proline, at position 305 with isoleucine, and at position 396 with leucine; or a substitution at position 243 leucine, at position 292 with proline, and at position 305 with isoleucine; or a substitution at position 292 with proline, at position 305 with isoleucine, and at position 396 with leucine; or a substitution at position 243 with leucine, and at position 292 with proline; or a substitution at position 292 with proline; or a substitution at position 243 with leucine, at position 292 with proline, and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine; or a substitution at position 243 with leucine.

[0252] In a specific embodiment, the molecule of the invention comprising a variant Fc region with an enhanced affinity for FcγRIIIA and a lowered affinity or no affinity for FcγRIIB as determined based on an ELISA assay and/or an ADCC based assay using ch-4-4-20 antibody carrying the variant Fc region comprises a substitution at position 379 with methionine; at position 219 with tyrosine; at position 282 with methionine; at position 401 with valine; at position 222 with asparagine; at position 334 with isoleucine; at position 334 with glutamic acid; at position 275 with tyrosine; at position 398 with valine. In yet another specific embodiment, the molecule of the invention comprising a variant Fc region with an enhanced affinity for FcγRIIIA and a lowered affinity or no affinity for FcγRIIB as determined based on an ELISA assay and/or an ADCC based assay using ch-4-4-20 antibody, or a surface plasmon resonance assay using a chimeric 4D5 antibody, carrying the variant Fc region comprises a substitution at position 243 with leucine; at position 292 with proline; and at position 300 with leucine.

[0253] The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIB with about a 3 fold lower affinity than a comparable polypeptide comprising the wild-type Fc region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 288 with asparagine, at position 330 with serine, and at position 396 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIB with about a 10-15 fold lower affinity than a comparable polypeptide comprising the wild-type Fc region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 316 with aspartic acid, at position 378 with valine, and at position 399 with glutamic acid. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIB with about a 10 fold lower affinity than a comparable polypeptide comprising the wild-type Fc region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 315 with isoleucine, at position 379 with methionine, and at position 399 with glutamic acid. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIB with about a 7 fold lower affinity than a comparable polypeptide comprising the wild-type Fc region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 243 with isoleucine, at position 379 with leucine, and at position 420 with valine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIB with about a 3 fold lower affinity than a comparable polypeptide comprising the wild-type Fc region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 392 with threonine and at position 396 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIB with about a 5 fold lower affinity than a comparable polypeptide comprising the wild-type Fc region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 268 with asparagine and at position 396 with leucine. The invention also encompasses an isolated polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said polypeptide specifically binds FcγRIIB with about a 2 fold lower affinity than a comparable polypeptide comprising the wild-type Fc region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 319 with phenylalanine, at position 352 with leucine, and at position 396 with leucine.

[0254] C. Mutants with Enhanced Affinity to FcγRIIA and FcγRIIB

[0255] The invention encompasses molecules comprising variant Fc regions, having one or more amino acid modifications, which modifications increase the affinity of the variant Fc region for FcγRIIIA and FcγRIIB by at least 65%, at least 70%, at least 75%, at least 85%, at least 90%, at least 95%, at least 99%, at least 100%, at least 200%, at least 300%, at least 400% and decreases the affinity of the variant Fc region for FcγRIIB by at least 65%, at least 70%, at least 75%, at least 85%, at least 90%, at least 95%, at least 99%, at least 100%, at least 200%, at least 300%, at least 400%. In a specific embodiment, the molecule of the invention comprising a variant Fc region with an enhanced affinity for FcγRIIIA and an enhanced affinity for FcγRIIB (as determined based on an ELISA assay and/or an ADCC based assay using ch-4-4-20 antibody, or a surface plasmon resonance assay using a chimeric 4D5 antibody, carrying the variant Fc region as described herein) comprises a substitution at position 415 with isoleucine and at position 251 with phenylalanine; or a substitution at position 399 with glutamic acid, at position 292 with leucine, and at position 185 with methionine; or a substitution at position 408 with isoleucine, at position 215 with isoleucine, and at position 125 with leucine; or a substitution at position 385 with glutamic acid and at position 247 with histidine; or a substitution at position 348 with methionine, at position 334 with asparagine, at position 275 with isoleucine, at position 202 with methionine and at position 147 with threonine; or a substitution at position 246 with threonine and at position 396 with histidine; or a substitution at position 268 with aspartic acid and at position 318 with aspartic acid; or a substitution at position 288 with asparagine, at position 330 with serine and at position 396 with leucine; or a substitution at position 244 with histidine, at position 358 with methionine, at position 379 with methionine, at position 384 with lysine and at position 397 with methionine; or a substitution at position 217 with serine, at position 378 with valine, and at position 408 with arginine; or a substitution at position 247 with leucine, at position 253 with asparagine, and at position 334 with asparagine; or a substitution at position 246 with isoleucine and at position 334 with asparagine; or a substitution at position 320 with glutamic acid and at position 326 with glutamic acid; or a substitution at position 375 with cysteine and at position 396 with leucine; or a substitution at position 343 with serine, at position 353 with leucine, at position 375 with isoleucine, at position 383 with asparagine; or a substitution at position 394 with methionine and at position 397 with methionine; or a substitution at position 216 with aspartic acid, at position 345 with lysine and at position 375 with isoleucine; or a substitution at position 288 with asparagine, at position 330 with serine, and at position 396 with leucine; or a substitution at position 247 with leucine and at position 389 with glycine; or a substitution at position 222 with asparagine, at position 335 with asparagine, at position 370 with glutamic acid, at position 378 with valine and at position 394 with methionine; or a substitution at position 316 with aspartic acid, at position 378 with valine and at position 399 with glutamic acid; or a substitution at position 315 with isoleucine, at position 379 with methionine, and at position 394 with methionine; or a substitution at position 290 with threonine and at position 371 with aspartic acid; or a substitution at position 247 with leucine and at position 398 with glutamine; or a substitution at position 326 with glutamine; at position 334 with glutamic acid, at position 359 with asparagine, and at position 366 with serine; or a substitution at position 247 with leucine and at position 377 with phenylalanine; or a substitution at position 378 with valine, at position 390 with isoleucine and at position 422 with isoleucine; or a substitution at position 326 with glutamic acid and at position 385 with glutamic acid; or a substitution at position 282 with glutamic acid, at position 369 with isoleucine and at position 406 with phenylalanine; or a substitution at position 397 with methionine; at position 411 with alanine and at position 415 with asparagine; or a substitution at position 223 with isoleucine, at position 256 with serine and at position 406 with phenylalanine; or a substitution at position 298 with asparagine and at position 407 with arginine; or a substitution at position 246 with arginine, at position 298 with asparagine, and at position 377 with phenylalanine; or a substitution at position 235 with proline, at position 382 with methionine, at position 304 with glycine, at position 305 with isoleucine, and at position 323 with isoleucine; or a substitution at position 247 with leucine, at position 313 with arginine, and at position 388 with glycine; or a substitution at position 221 with tyrosine, at position 252 with isoleucine, at position 330 with glycine, at position 339 with threonine, at position 359 with asparagine, at position 422 with isoleucine, and at position 433 with leucine; or a substitution at position 258 with aspartic acid, and at position 384 with lysine; or a substitution at position 241 with leucine and at position 258 with glycine; or a substitution at position 370 with asparagine and at position 440 with asparagine; or a substitution at position 317 with asparagine and a deletion at position 423; or a substitution at position 243 with isoleucine, at position 379 with leucine and at position 420 with valine; or a substitution at position 227 with serine and at position 290 with glutamic acid; or a substitution at position 231 with valine, at position 386 with histidine, and at position 412 with methionine; or a substitution at position 215 with proline, at position 274 with asparagine, at position 287 with glycine, at position 334 with asparagine, at position 365 with valine and at position 396 with leucine; or a substitution at position 293 with valine, at position 295 with glutamic acid and at position 327 with threonine; or a substitution at position 319 with phenylalanine, at position 352 with leucine, and at position 396 with leucine; or a substitution at position 392 with threonine and at position 396 with leucine; at a substitution at position 268 with asparagine and at position 396 with leucine; or a substitution at position 290 with threonine, at position 390 with isoleucine, and at position 396 with leucine; or a substitution at position 326 with isoleucine and at position 396 with leucine; or a substitution at position 268 with aspartic acid and at position 396 with leucine; or a substitution at position 210 with methionine and at position 396 with leucine; or a substitution at position 358 with proline and at position 396 with leucine; or a substitution at position 288 with arginine, at position 307 with alanine, at position 344 with glutamic acid, and at position 396 with leucine; or a substitution at position 273 with isoleucine, at position 326 with glutamic acid, at position 328 with isoleucine and at position 396 with leucine; or a substitution at position 326 with isoleucine, at position 408 with asparagine and at position 396 with leucine; or a substitution at position 334 with asparagine and at position 396 with leucine; or a substitution at position 379 with methionine and at position 396 with leucine; or a substitution at position 227 with serine and at position 396 with leucine; or a substitution at position 217 with serine and at position 396 with leucine; or a substitution at position 261 with asparagine, at position 210 with methionine and at position 396 with leucine; or a substitution at position 419 with histidine and at position 396 with leucine; or a substitution at position 370 with glutamic acid and at position 396 with leucine; or a substitution at position 242 with phenylalanine and at position 396 with leucine; or a substitution at position 255 with leucine and at position 396 with leucine; or a substitution at position 240 with alanine and at position 396 with leucine; or a substitution at position 250 with serine and at position 396 with leucine; or a substitution at position 247 with serine and at position 396 with leucine; or a substitution at position 410 with histidine and at position 396 with leucine; or a substitution at position 419 with leucine and at position 396 with leucine; or a substitution at position 427 with alanine and at position 396 with leucine; or a substitution at position 258 with aspartic acid and at position 396 with leucine; or a substitution at position 384 with lysine and at position 396 with leucine; or a substitution at position 323 with isoleucine and at position 396 with leucine; or a substitution at position 244 with histidine and at position 396 with leucine; or a substitution at position 305 with leucine and at position 396 with leucine; or a substitution at position 400 with phenylalanine and at position 396 with leucine; or a substitution at position 303 with isoleucine and at position 396 with leucine; or a substitution at position 243 with leucine, at position 305 with isoleucine, at position 378 with aspartic acid, at position 404 with serine and at position 396 with leucine; or a substitution at position 290 with glutamic acid, at position 369 with alanine, at position 393 with alanine and at position 396 with leucine; or a substitution at position 210 with asparagine, at position 222 with isoleucine, at position 320 with methionine and at position 396 with leucine; or a substitution at position 217 with serine, at position 305 with isoleucine, at position 309 with leucine, at position 390 with histidine and at position 396 with leucine; or a substitution at position 246 with asparagine; at position 419 with arginine and at position 396 with leucine; or a substitution at position 217 with alanine, at position 359 with alanine and at position 396 with leucine; or a substitution at position 215 with isoleucine, at position 290 with valine and at position 396 with leucine; or a substitution at position 275 with leucine, at position 362 with histidine, at position 384 with lysine and at position 396 with leucine; or a substitution at position 334 with asparagine; or a substitution at position 400 with proline; or a substitution at position 407 with isoleucine; or a substitution at position 372 with tyrosine; or a substitution at position 366 with asparagine; or a substitution at position 414 with asparagine; or a substitution at position 352 with leucine; or a substitution at position 225 with serine; or a substitution at position 377 with asparagine; or a substitution at position 248 with methionine; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine; or a substitution at position 243 with leucine, and at position 396 with leucine; or at position 292 with proline, and at position 305 with isoleucine.

[0256] D. Mutants that do Not Bind any FcγR

[0257] In some embodiments, the invention encompasses molecules comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, which variant Fc region does not bind any FcγR, as determined by standard assays known in the art and disclosed herein, relative to a comparable molecule comprising the wild type Fc region. In a specific embodiment, the one or more amino acid modifications which abolish binding to all FcγRs comprise a substitution at position 232 with serine and at position 304 with glycine; or a substitution at position 269 with lysine, at position 290 with asparagine, at position 311 with arginine, and at position 433 with tyrosine; or a substitution at position 252 with leucine; or a substitution at position 216 with aspartic acid, at position 334 with arginine, and at position 375 with isoleucine; or a substitution at position 247 with leucine and at position 406 with phenylalanine, or a substitution at position 335 with asparagine, at position 387 with serine, and at position 435 with glutamine; or a substitution at position 334 with glutamic acid, at position 380 with aspartic acid, and at position 446 with valine; or a substitution at position 303 with isoleucine, at position 369 with phenylalanine, and at position 428 with leucine; or a substitution at position 251 with phenylalanine and at position 372 with leucine; or a substitution at position 246 with glutamic acid, at position 284 with methionine and at position 308 with alanine; or a substitution at position 399 with glutamic acid and at position 402 with aspartic acid; or a substitution at position 399 with glutamic acid and at position 428 with leucine.

[0258] D. Mutants with Altered FcγR-Mediated Effector Functions

[0259] The invention encompasses immunoglobulin comprising Fc variants with altered effector functions. In some embodiments, immunoglobulins comprising Fc variants mediate effector function more effectively in the presence of effector cells as determined using assays known in the art and exemplified herein. In other embodiments, immunoglobulins comprising Fc variants mediate effector function less effectively in the presence of effector cells as determined using assays known in the art and exemplified herein. In specific embodiments, the Fc variants of the invention may be combined with other known Fc modifications that alter effector function, such that the combination has an additive, synergistic effect. The Fc variants of the invention have altered effector function in vitro and/or in vivo.

[0260] In a specific embodiment, the immunoglobulins of the invention with enhanced affinity for FcγRIIIA and/or FcγRIIA have an enhanced FcγR-mediated effector function as determined using ADCC activity assays disclosed herein. Examples of effector functions that could be mediated by the molecules of the invention include, but are not limited to, C1q binding, complement-dependent cytotoxicity, antibody-dependent cell mediate cytotoxicity (ADCC), phagocytosis, etc. The effector functions of the molecules of the invention can be assayed using standard methods known in the art, examples of which are disclosed in Section 5.2.6. In a specific embodiment, the immunoglobulins of the invention comprising a variant Fc region with enhanced affinity for FcγRIIIA and/or FcγRIIA mediate antibody dependent cell mediated cytotoxicity (ADCC) 2-fold more effectively, than an immunoglobulin comprising a wild-type Fc region. In other embodiments, the immunoglobulins of the invention comprising a variant Fc region with enhanced affinity for FcγRIIIA and/or FcγRIIA mediate antibody dependent cell mediated cytotoxicity (ADCC) at least 4-fold, at least 8-fold, at least 10-fold, at least 100-fold, at least 1000-fold, at least 10⁴-fold, at least 10⁵-fold more effectively, than an immunoglobulin comprising a wild-type Fc region. In another specific embodiment, the immunoglobulins of the invention with enhanced affinity for FcγRIIIA and/or FcγRIIA have altered C1q binding activity. In some embodiments, the immunoglobulins of the invention with enhanced affinity for FcγRIIIA and/or FcγRIIA have at least 2-fold, at least 4-fold, at least 8-fold, at least 10-fold, at least 100-fold, at least 1000-fold, at least 10⁴-fold, at least 10⁵-fold higher C1q binding activity than an immunoglobulin comprising a wild-type Fc region. In yet another specific embodiment, the immunoglobulins of the invention with enhanced affinity for FcγRIIIA and/or FcγRIIA have altered complement dependent cytotoxicity. In yet another specific embodiment, the immunoglobulins of the invention with enhanced affinity for FcγRIIIA and/or FcγRIIA have an enhanced complement dependent cytotoxicity than an immunoglobulin comprising a wild-type Fc region. In some embodiments, the immunoglobulins of the invention with enhanced affinity for FcγRIIIA and/or FcγRIIA have at least 2-fold, at least 4-fold, at least 8-fold, at least 10-fold, at least 100-fold, at least 1000-fold, at least 10⁴-fold, at least 10⁵-fold higher complement dependent cytotoxicity than an immunoglobulin comprising a wild-type Fc region.

[0261] In other embodiments, immunoglobulins of the invention with enhanced affinity for FcγRIIIA and/or FcγRIIA have enhanced phagocytosis activity relative to an immunoglobulin comprising a wild-type Fc region, as determined by standard assays known to one skilled in the art or disclosed herein. In some embodiments, the immunoglobulins of the invention with enhanced affinity for FcγRIIIA and/or FcγRIIA have at least 2-fold, at least 4-fold, at least 8-fold, at least 10-fold higher phagocytosis activity relative to an immunoglobulin comprising a wild-type Fc region.

[0262] In a specific embodiment, the invention encompasses an immunoglobulin comprising a variant Fc region with one or more amino acid modifications, with an enhanced affinity for FcγRIIIA and/or FcγRIIA such that the immunoglobulin has an enhanced effector function, e.g., antibody dependent cell mediated cytotoxicity, or phagocytosis. In a specific embodiment, the one or more amino acid modifications which increase the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA and increase the ADCC activity of the immunoglobulin comprise a substitution at position 379 with methionine; or a substitution at position 243 with isoleucine and at position 379 with leucine; or a substitution at position 288 with asparagine, at position 330 with serine, and at position 396 with leucine; or a substitution at position 243 leucine and at position 255 with leucine; or a substitution at position 334 with glutamic acid, at position 359 with asparagine, and at position 366 with serine; or a substitution at position 288 with methionine and at position 334 with glutamic acid; or a substitution at position 334 with glutamic acid and at position 292 with leucine; or a substitution at position 316 with aspartic acid, at position 378 with valine, and at position 399 with glutamic acid; or a substitution at position 315 with isoleucine, at position 379 with methionine, and at position 399 with glutamic acid; or a substitution at position 243 with isoleucine, at position 379 with leucine, and at position 420 with valine; or a substitution at position 247 with leucine and at position 421 with lysine; or a substitution at position 248 with methionine; or a substitution at position 392 with threonine and at position 396 with leucine; or a substitution at position 293 with valine, at position 295 with glutamic acid, and at position 327 with threonine; or a substitution at position 268 with asapragine and at position 396 with leucine; or a substitution at position 319 with phenylalanine, at position 352 with leucine, and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, and at position 300 with leucine.

[0263] In another specific embodiment, the one or more amino acid modifications which increase the ADCC activity of the immunoglobulin is any of the mutations listed below, in table 7.

TABLE 7
AMINO ACID MODIFICATION WHICH INCREASE ADCC
	E333A, K334A
	R292L, K334E
	V379M
	S219Y
	V282M
	K222N
	F243I, V379L,
	F243L, R255L, E318K
	K334I
	K334E, T359N, T366S
	K288M, K334E
	K288N, A330S, P396L
	K326E
	G316D, A378V, D399E
	N315I, V379M, T394M
	F243I, V379L, G420V
	E293V, Q295E, A327T
	Y319F, P352L, P396L
	K392T, P396L
	K248M
	H268N, P396L
	K290T, N390I, P396L
	K326I, P396L
	H268D, P396L
	K210M, P396L
	L358P, P396L
	K288R, T307A, K344E, P396L
	V273I, K326E, L328I, P396L
	K326I, S408N, P396L
	K334N, P396L
	V379M, P396L
	P227S, P396L
	P217S, P396L
	K261N, K210M, P396L
	Q419H, P396L
	K370E, P396L
	L242F, P396L
	F243L, V305I, A378D, F404S, P396L
	R255L, P396L
	V240A, P396L
	T250S, P396L
	P247S, P396L
	K290E, V369A, T393A, P396L
	K210N, K222I, K320M, P396L
	L410H, P396L
	Q419L, P396L
	V427A, P396L
	P217S, V305I, I309L, N390H, P396L
	E258D, P396L
	N384K, P396L
	V323I, P396L
	K246N, Q419R, P396L
	P217A, T359A, P396L
	P244H, P396L
	V215I, K290V, P396L
	F275L, Q362H, N384K, P396L
	V305L, P396L
	S400F, P396L
	V303I, P396L
	D270E, G316D, R416G
	P247L, N421K
	P247L, N421K, D270E
	Q419H, P396L, D270E
	K370E, P396L, D270E
	R255L, P396L, D270E
	V240A, P396L, D270E
	K392T, P396L, D270E
	F243L, R292P, Y300L, V305I, P396L
	F243L, R292P, Y300L, P396L
	F243L, R292P, Y300L

[0264] Alternatively or additionally, it may be useful to combine the above amino acid modifications or any other amino acid modifications disclosed herein with one or more further amino acid modifications that alter C1q binding and/or complement dependent cytoxicity function of the Fc region. The starting molecule of particular interest herein is usually one that binds to C1q and displays complement dependent cytotoxicity (CDC). The further amino acid substitutions described herein will generally serve to alter the ability of the starting molecule to bind to C1q and/or modify its complement dependent cytotoxicity function, e.g., to reduce and preferably abolish these effector functions. However, molecules comprising substitutions at one or more of the described positions with improved C1q binding and/or complement dependent cytotoxicity (CDC) function are contemplated herein. For example, the starting molecule may be unable to bind C1q and/or mediate CDC and may be modified according to the teachings herein such that it acquires these further effector functions. Moreover, molecules with preexisting C1q binding activity, optionally further having the ability to mediate CDC may be modified such that one or both of these activities are enhanced.

[0265] As disclosed above, one can design an Fc region with altered effector function, e.g., by modifying C1q binding and/or FcR binding and thereby changing CDC activity and/or ADCC activity. For example, one can generate a variant Fc region with improved C1q binding and improved FcγRIII binding; e.g., having both improved ADCC activity and improved CDC activity. Alternatively, where one desires that effector function be reduced or ablated, one may engineer a variant Fc region with reduced CDC activity and/or reduced ADCC activity. In other embodiments, one may increase only one of these activities, and optionally also reduce the other activity, e.g., to generate an Fc region variant with improved ADCC activity, but reduced CDC activity and vice versa.

[0266] The invention encompasses specific variants of the Fc region that have been identified using the methods of the invention from a yeast library of mutants after 2nd-4th-round of sorting are listed in Table 8. Table 8 summarizes the various mutants that were identified using the methods of the invention. The mutants were assayed using an ELISA assay for determining binding to FcγRIIIA and FcγRIIB. The mutants were also tested in an ADCC assay, by cloning the Fc variants into a ch 4-4-20 antibody using methods disclosed and exemplified herein. Bolded items refer to experiments, in which the ch4-4-20 were purified prior the ADCC assay. The antibody concentration used was in the range 0.5 μg/mL-1.0 μg/mL.

TABLE 8
MUTATIONS IDENTIFIED IN THE Fc REGION
			Binding	4-4-20
		Binding to	to	ADCC
		FcγRIIIA	FcγRIIB	(Relative Lysis
Mutations	Domain	(ELISA)	(ELISA)	(Mut/Wt)
pYD-CH1 library FACS screen with 3A tetramer
Q347H; A339V	CH3	↑0.5x	NT
S415I; L251F	CH2, CH3	↑0.5x	↑ .75x	0.82
K392R	CH3	N/C	NT
D399E; R292L; V185M	CH1, CH2, CH3	N/C	↑0.5x	0.65
				0.9
K290E; L142P	CH1, CH2	N/C	NT
R301C; M252L; S192T	CH1, CH2	↓.5x	NT
P291S; K288E; H268L: A141V	CH1, CH2	↓.5x	NT
N315I	CH2	N/C	↑ .75x
S132I	CH1	N/C	NT
S383N; N384K; T256N; V262L; K218E; R214I; K205E; F149Y; K133M	All	↑0.5x	NT
S408I; V215I; V125L	CH1, CH2, CH3	↑0.5x	↑ .75x	0.62
P396L	CH3	↑1x	↑1x	0.55
G385E; P247H;	CH2, CH3	↑1x	↑ .75x	0.44
P396H	CH3	↑1x	↑1x	0.58
A162V	CH1	N/C	NT
V348M; K334N; F275I; Y202M; K147T	CH1, CH2, CH3	↑0.5x	↑.75x	0.33
H310Y; T289A; G337E	CH2	↑.5x	NT
S119F; G371S; Y407V; E258D	CH1, CH2, CH3	N/C	N/C	0.29
K409R; S166N	CH1, CH3	N/C	NT
in vitro Site Directed mutants
R292L	CH2	NT	NT	0.82
T359N	CH3	NT	NT	1.06
T366S	CH3	NT	NT	0.93
E333A, K334A	CH2	NT	NT	1.41
R292L, K334E	CH2	NT	NT	1.41; 1.64
R292L, P396L, T359N	CH2, CH3	NT	NT	0.89; 1.15
V379L	CH3	NT	NT	0.83
K288N	CH2	NT	NT	0.78
A330S	CH2	NT	NT	0.52
F243L	CH2	NT	NT	0.38
E318K	CH2	NT	NT	0.86
K288N, A330S	CH2	NT	NT	0.08
R255L, E318K	CH2	NT	NT	0.82
F243L, E318K	CH2	NT	NT	0.07
Mutants in 4-4-20 mini-library
Increased FcγRIIIA binding, decreased or no change to FcγRIIB binding
N/C means no change; N/B means no binding; NT means not tested
V379M	CH3	↑2x	N/C	1.47
S219Y	Hinge	↑1x	↓ or N/B	1.28
V282M	CH2	↑1x	↓ or N/B	1.25; 1
F275I, K334N, V348M	CH2	↑0.5x	N/C
D401V	CH3	↑ 0.5x	N/C
V279L, P395S	CH2	↑ 1x	N/C
K222N	Hinge	↑ 1x	↓or N/B	1.33; 0.63
K246T, Y319F	CH2	↑ 1x	N/C
F243I, V379L	CH2, CH3	↑1.5x	↓ or N/B	1.86; 1.35
F243L, R255L, E318K	CH2	↑ 1x	↓ or N/B	1.81; 1.45
K334I	CH2	↑ 1x	N/C	2.1; 1.97
K334E, T359N, T366S	CH2, CH3	↑1.5x	N/C	1.49; 1.45
K288M, K334E	CH2	↑ 3x	↓ or N/B	1.61; 1.69
K334E, E380D	CH2, CH3	↑1.5x	N/C
T256S, V305I, K334E, N390S	CH2, CH3	↑1.5x	N/C
K334E	CH2	↑2.5x	N/C	1.75; 2.18
T335N, K370E, A378V, T394M, S424L	CH2, CH3	↑0.5x	N/C
E233D, K334E	CH2	↑1.5x	N/C	0.94; 1.02
K334E, T359N, T366S, Q386R	CH2	↑ 1x	N/C
Increased Binding to FcγIIIA and FcγRIIB
K246T, P396H	CH2, CH3	↑ 1x	↑ 2.5x
H268D, E318D	CH2	↑1.5x	↑ 5x
K288N, A330S, P396L	CH2, CH3	↑ 5x	↑ 3x	2.34; 1.66; 2.54
I377F	CH3	↑1.5x	↑0.5x
P244H, L358M, V379M, N384K, V397M	CH2, CH3	↑1.75x	↑1.5x
P217S, A378V, S408R	Hinge, CH3	↑ 2x	↑4.5x
P247L, I253N, K334N	CH2	↑ 3x	↑ 2.5x
P247L	CH2	↑0.5x	↑ 4x	0.91; 0.84
F372Y	CH3	↑0.75x	↑5.5x	0.88; 0.59
K326E	CH2	↑ 2x	↑ 3.5x	1.63; 2
K246I, K334N	CH2	↑0.5x	↑ 4x	0.66; 0.6
K320E, K326E	CH2	↑ 1x	↑ 1x
H224L	Hinge	↑0.5x	↑ 5x	0.55;
				0.53
S375C, P396L	CH3	↑1.5x	↑4.5x
D312E, K327N, I378S	CH2, CH3	↑0.5x	N/C
K288N, K326N	CH2	↑ 1x	N/C
F275Y	CH2	↑ 3x	N/C	0.64
P247L, N421K	CH2, CH3	↑ 3x	N/C	2.0
S298N, W381R	CH2, CH3	↑ 2x	N/C
D280E, S354F, A431D, L441I	CH2, CH3	↑ 3x	N/C	0.62
R255Q, K326E	CH2	↑ 2x	N/C	0.79
K218R, G281D, G385R	H, CH2, CH3	↑3.5x	N/C	0.67
L398V	CH3	↑1.5x	N/C
P247L, A330T, S440G	CH2, CH3	↑0.75x	↓ 0.25x
V284A, F372L	CH2, CH3	1x	N/C
T335N, P387S, H435Q	CH2, CH3	1.25x	N/C
P247L, A431V, S442F	CH2, CH3	1x	N/C
Increased Binding to FcγRIIIA and FcγRIIB
P343S, P353L, S375I, S383N	CH3	↑ 0.5x	↑ 6x
T394M, V397M	CH3	↑ 0.5x	↑ 3x
E216D, E345K, S375I	H, CH2, CH3	↑ 0.5x	↑ 4x
K334N,	CH2	↑0.5x	↑ 2x
K288N, A330S, P396L	CH2, CH3	↑0.5x	↑ 9x
P247L, E389G	CH2, CH3	↑1.5x	↑ 9x
K222N, T335N, K370E, A378V, T394M	H, CH2, CH3	↑ 1x	↑ 7x
G316D, A378V, D399E	CH2, CH3	↑1.5x	↑ 14x	2.24
N315I, V379M, T394M	CH2, CH3	↑ 1x	↑ 9x	1.37
K290T, G371D,	CH2, CH3	↑ 0.25x	↑ 6x
P247L, L398Q	CH2, CH3	↑ 1.25x	↑ 10x
K326Q, K334E, T359N, T366S	CH2, CH3	↑ 1.5x	↑ 5x
S400P	CH3	↑ 1x	↑ 6x
P247L, I377F	CH2, CH3	↑ 1x	↑ 5x
A378V, N3901, V422I	CH3	↑ 0.5x	↑ 5x
K326E, G385E	CH2, CH3	↑0.5x	↑15x
V282E, V369I, L406F	CH2, CH3	↑ 0.5x	↑ 7x
V397M, T411A, S415N	CH3	↑ 0.25x	↑5x
T223I, T256S, L406F	H, CH2, CH3	↑ 0.25x	↑ 6x
S298N, S407R	CH2, CH3	↑0.5x	↑ 7x
K246R, S298N, I377F	CH2, CH3	↑ 1x	↑ 5x
S407I	CH3	↑ 0.5x	↑4x
F372Y	CH3	↑0.5x	↑4x
L235P, V382M, S304G, V305I, V323I	CH2, CH3	↑ 2x	↑ 2x
P247L, W313R, E388G	CH2, CH3	↑1.5x	↑1x
D221Y, M252I, A330G, A339T, T359N, V422I, H433L	H, CH2, CH3	↑2.5x	↑ 6x
E258D, N384K	CH2, CH3	↑1.25x	↑4x
F241L, E258G	CH2	↑ 2x	↑ 2.5x	−0.08
K370N, S440N	CH3	↑1x	↑ 3.5x
K317N, F423-deleted	CH2, CH3	↑ 2.5x	↑ 7x	0.18
F243I, V379L, G420V	CH2, CH3	↑ 2.5x	↑3.5x	1.35
P227S, K290E	H, CH2	↑ 1x	↑ 0.5x
A231V, Q386H, V412M	CH2, CH3	↑1.5x	↑ 6x
T215P, K274N, A287G, K334N, L365V, P396L	H, CH2, CH3	↑2x	↑ 4x
Increased Binding to FcγRIIB but not FcγRIIIA
K334E, E380D	CH2, CH3	N/C	↑4.5x
T366N	CH3	N/C	↑ 5x
P244A, K326I, C367R, S375I, K447T	CH2, CH3	N/C	↑ 3x
C229Y, A287T, V379M, P396L, L443V	H, CH2, CH3	↓ 0.25x	↑10x
Decreased binding to FcγRIIIA and FcγRIIB
R301H, K340E, D399E	CH2, CH3	↓ 0.50x	↓ 0.25x
K414N	CH3	↓ 0.25x	N/B
P291S, P353Q	CH2, CH3	↓ 0.50x	↓ 0.25x
V240I, V281M	CH2	↓ 0.25x	↓ 0.25x
P232S, S304G	CH2	N/B	N/B
E269K, K290N, Q311R, H433Y	CH2, CH3	N/B	N/B
M352L	CH3	N/B	N/B
E216D, K334R, S375I	H, CH2, CH3	N/B	N/B
P247L, L406F	CH2, CH3	N/B	N/B
T335N, P387S, H435Q	CH2, CH3	N/B	N/B
T225S	CH2	↓ 0.25x	↓ 0.50x
D399E, M428L	CH3	↓ 0.50x	↓ 0.50x
K246I, Q362H, K370E	CH2, CH3	N/B	↓ 0.50x
K334E, E380D, G446V	CH2, CH3	N/B	N/B
I377N	CH3	↓ 0.50x	N/B
V303I, V369F, M428L	CH2, CH3	N/B	N/B
L251F, F372L	CH2, CH3	N/B	N/B
K246E, V284M, V308A	CH2, CH3	N/B	N/B
D399E, G402D	CH3	N/B	N/B
D399E, M428L	CH3	N/B	N/B
FcγRIIB depletion/FcγRIIIA selection: Naive Fc library.
E293V, Q295E, A327T	CH2	↑0.4x	↓ or N/B	4.29
Y319F, P352L, P396L	CH2, CH3	↑3.4x	↑2x	1.09
K392T, P396L	CH3	↑ 4.5x	↑ 2.5x	3.07
K248M	CH2	↑0.4x	↓ or N/B	4.03
H268N, P396L	CH2, CH3	↑ 2.2x	↑ 4.5x	2.24
Solution competition 40X FcγRIIB-G2: P396L Library
D221E, D270E, V308A, Q311H, P396L, G402D		↑3.6x	↑0.1x	3.17
Equilibrium Screen: 0.8 μM FcγRIIIA monomer: P396L library
K290T, N390I, P396L	CH2, CH3	↑2.8x	↑ 6.1x	1.93
K326I, P396L	CH2, CH3	↑2.9x	↑ 5.9x	1.16
H268D, P396L	CH2, CH3	↑3.8x	↑13.7x	2.15
K210M, P396L	CH1, CH3	↑1.9x	↑ 4.6x	2.02
L358P, P396L	CH3	↑1.9x	↑ 4.2x	1.58
K288R, T307A, K344E, P396L	CH2, CH3	↑ 4.1x	↑ 2.3x	3.3
V273I, K326E, L328I, P396L	CH2, CH3	↑ 1.3x	↑10.8x	0.78
K326I, S408N, P396L	CH2, CH3	↑4x	↑ 9.3x	1.65
K334N, P396L	CH2, CH3	↑3.1x	↑ 3x	2.43
V379M, P396L	CH3	↑1.9x	↑5.6x	2.01
P227S, P396L	CH2, CH3	↑1.5x	↑ 4x	2.01
P217S, P396L	H, CH3	↑1.6x	↑4.5x	2.04
K261N, K210M, P396L	CH2, CH3	↑ 2x	↑ 4.2x	2.06
Kinetic Screen: O.8 μM, 1′ with cold 8 μM FcγRIIIA: P396L Library
term is M, P396L	CH3	↑1.9x	↑ 7.2x	3.09
Q419H, P396L	CH3	↑ 2x	↑ 6.9x	2.24
K370E, P396L	CH3	↑2x	↑6.6x	2.47
L242F, P396L	CH2, CH3	↑ 2.5x	↑ 4.1x	2.4
F243L, V305I, A378D, F404S, P396L	CH2, CH3	↑1.6x	↑5.4x	3.59
R255L, P396L	CH2, CH3	↑1.8x	↑ 6x	2.79
V240A, P396L	CH2, CH3	↑ 1.3x	↑ 4.2x	2.35
T250S, P396L	CH2, CH3	↑ 1.5x	↑6.8x	1.60
P247S, P396L	CH2, CH3	↑ 1.2x	↑ 4.2x	2.10
K290E, V369A, T393A, P396L	CH2, CH3	↑1.3x	↑ 6.7x	1.55
K210N, K222I, K320M, P396L	H, CH2, CH3	↑ 2.7x	↑ 8.7x	1.88
L410H, P396L	CH3	↑ 1.7x	↑ 4.5x	2.00
Q419L, P396L	CH3	↑ 2.2x	↑ 6.1x	1.70
V427A, P396L	CH3	↑ 1.9x	↑4.7x	1.67
P217S, V305I, I309L, N390H, P396L	H, CH2, CH3	↑2x	↑ 7x	1.54
E258D, P396L	CH2, CH3	↑ 1.9x	↑ 4.9x	1.54
N384K, P396L	CH3	↑ 2.2x	↑5.2x	1.49
V323I, P396L	CH2, CH3	↑ 1.1x	↑ 8.2x	1.29
K246N, Q419R, P396L	CH2, CH3	↑1.1x	↑ 4.8x	1.10
P217A, T359A, P396L	H, CH2, CH3	↑1.5x	↑ 4.8x	1.17
P244H, P396L	CH2, CH3	↑2.5x	↑ 4x	1.40
V215I, K290V, P396L	H, CH2, CH3	↑2.2x	↑ 4.6x	1.74
F275L, Q362H, N384K, P396L	CH2, CH3	↑ 2.2x	↑ 3.7x	1.51
V305L, P396L	CH2, CH3	↑1.3x	↑ 5.5x	1.50
S400F, P396L	CH3	↑1.5x	↑4.7x	1.19
V303I, P396L	CH3	↑1.1x	↑ 4x	1.01
FcγRIIB depletion FcγRIIIA 158V solid phase selection: Naïve Library
A330V, H433Q, V427M	CH2, CH3	NT	NT	NT
V263Q, E272D, Q419H	CH2, CH3	NT	NT	NT
N276Y, T393N, W417R	CH2, CH3	NT	NT	NT
V282L, A330V, H433Y, T436R	CH2, CH3	NT	NT	NT
A330V, Q419H	CH2, CH3	NT	NT	NT
V284M, S298N, K334E, R355W	CH2, CH3	NT	NT	NT
A330V, G427M, K438R	CH2, CH3	NT	NT	NT
S219T, T225K, D270E, K360R	CH2, CH3	NT	NT	NT
K222E, V263Q, S298N	CH2	NT	NT	NT
V263Q, E272D	CH2	NT	NT	NT
R292G	CH2	NT	NT	NT
S298N	CH2	NT	NT	NT
E233G, P247S, L306P	CH2	NT	NT	NT
D270E	CH2	NT	NT	NT
S219T, T225K, D270E	CH2	NT	NT	NT
K326E, A330T	CH2	NT	NT	NT
E233G	CH2	NT	NT	NT
S254T, A330V, N361D, P243L	CH2, CH3	NT	NT	NT
FcγRIIB depletion FcγRIIIA 158F solid phase selection: Naïve Library
158F by FACS top 0.2%
V284M, S298N, K334E, R355W R416T	CH2, CH3	NT	NT
FcγRIIB depletion FcgRIIA 131H solid phase selection: Naïve Library
R292P, V3051	CH2, CH2	NT	NT
D270E, G316D, R416G	CH2, CH3	NT	NT
V284M, R292L, K370N	CH2, CH3	NT	NT
R292P, V305I, F243L	CH2	NT	NT

[0267] In preferred embodiments, the invention provides modified immunoglobulin molecules (e.g., antibodies) with variant Fc regions, having one or more amino acid modifications, which one or more amino acid modifications increase the affinity of the molecule for FcγRIIIA and/or FcγRIIA. Such immunoglobulins include IgG molecules that naturally contain FcγR binding regions (e.g., FcγRIIIA and/or FcγRIIB binding region), or immunoglobulin derivatives that have been engineered to contain an FcγR binding region (e.g., FcγRIIIA and/or FcγRIIB binding region). The modified immunoglobulins of the invention include any immunoglobulin molecule that binds, preferably, immunospecifically, i.e., competes off non-specific binding as determined by immunoassays well known in the art for assaying specific antigen-antibody binding, an antigen and contains an FcγR binding region (e.g., a FcγRIIIA and/or FcγRIIB binding region). Such antibodies include, but are not limited to, polyclonal, monoclonal, bi-specific, multi-specific, human, humanized, chimeric antibodies, single chain antibodies, Fab fragments, F(ab′)₂ fragments, disulfide-linked Fvs, and fragments containing either a VL or VH domain or even a complementary determining region (CDR) that specifically binds an antigen, in certain cases, engineered to contain or fused to an FcγR binding region.

[0268] In some embodiments, the molecules of the invention comprise portions of an Fc region. As used herein the term “portion of an Fc region” refers to fragments of the Fc region, preferably a portion with effector activity and/or FcγR binding activity (or a comparable region of a mutant lacking such activity). The fragment of an Fc region may range in size from 5 amino acids to the entire Fc region minus one amino acids. The portion of an Fc region may be missing up to 10, up to 20, up to 30 amino acids from the N-terminus or C-terminus.

[0269] The IgG molecules of the invention are preferably IgG1 subclass of IgGs, but may also be any other IgG subclasses of given animals. For example, in humans, the IgG class includes IgG1, IgG2, IgG3, and IgG4; and mouse IgG includes IgG1, IgG2a, IgG2b, IgG2c and IgG3.

[0270] The immunoglobulins (and other polypeptides used herein) may be from any animal origin including birds and mammals. Preferably, the antibodies are human, rodent (e.g., mouse and rat), donkey, sheep, rabbit, goat, guinea pig, camel, horse, or chicken. As used herein, “human” antibodies include antibodies having the amino acid sequence of a human immunoglobulin and include antibodies isolated from human immunoglobulin libraries or from animals transgenic for one or more human immunoglobulin and that do not express endogenous immunoglobulins, as described infra and, for example, in U.S. Pat. No. 5,939,598 by Kucherlapati et al.

[0271] The antibodies of the present invention may be monospecific, bispecific, trispecific or of greater multispecificity. Multispecific antibodies may be specific for different epitopes of a polypeptide or may be specific for heterologous epitopes, such as a heterologous polypeptide or solid support material. See, e.g., PCT publications WO 93/17715; WO 92/08802; WO 91/00360; WO 92/05793; Tutt, et al., J. Immunol., 147:60-69, 1991; U.S. Pat. Nos. 4,474,893; 4,714,681; 4,925,648; 5,573,920; 5,601,819; Kostelny et al., J. Immunol., 148:1547-1553, 1992.

[0272] Multispecific antibodies have binding specificities for at least two different antigens. While such molecules normally will only bind two antigens (i.e. bispecific antibodies, BsAbs), antibodies with additional specificities such as trispecific antibodies are encompassed by the instant invention. Examples of BsAbs include without limitation those with one arm directed against a tumor cell antigen and the other arm directed against a cytotoxic molecule.

[0273] Methods for making bispecific antibodies are known in the art. Traditional production of full length bispecific antibodies is based on the coexpression of two immunoglobulin heavy chain-light chain pairs, where the two chains have different specificities (Millstein et al., Nature, 305:537-539 (1983); which is incorporated herein by reference in its entirety). Because of the random assortment of immunoglobulin heavy and light chains, these hybridomas (quadromas) produce a potential mixture of 10 different antibody molecules, of which only one has the correct bispecific structure. Purification of the correct molecule, which is usually done by affinity chromatography steps, is rather cumbersome, and the product yields are low. Similar procedures are disclosed in WO 93/08829, and in Traunecker et al., EMBO J., 10:3655-3659 (1991).

[0274] According to a different approach, antibody variable domains with the desired binding specificities (antibody-antigen combining sites) are fused to immunoglobulin constant domain sequences. The fusion preferably is with an immunoglobulin heavy chain constant domain, comprising at least part of the hinge, CH2, and CH3 regions. It is preferred to have the first heavy-chain constant region (CH1) containing the site necessary for light chain binding, present in at least one of the fusions. DNAs encoding the immunoglobulin heavy chain fusions and, if desired, the immunoglobulin light chain, are inserted into separate expression vectors, and are co-transfected into a suitable host organism. This provides for great flexibility in adjusting the mutual proportions of the three polypeptide fragments in embodiments when unequal ratios of the three polypeptide chains used in the construction provide the optimum yields. It is, however, possible to insert the coding sequences for two or all three polypeptide chains in one expression vector when, the expression of at least two polypeptide chains in equal ratios results in high yields or when the ratios are of no particular significance.

[0275] In a preferred embodiment of this approach, the bispecific antibodies are composed of a hybrid immunoglobulin heavy chain with a first binding specificity in one arm, and a hybrid immunoglobulin heavy chain-light chain pair (providing a second binding specificity) in the other arm. It was found that this asymmetric structure facilitates the separation of the desired bispecific compound from unwanted immunoglobulin chain combinations, as the presence of an immunoglobulin light chain in only one half of the bispecific molecule provides for a facile way of separation. This approach is disclosed in WO 94/04690. For further details of generating bispecific antibodies see, for example, Suresh et al., Methods in Enzymology, 121:210 (1986). According to another approach described in WO96/27011, a pair of antibody molecules can be engineered to maximize the percentage of heterodimers which are recovered from recombinant cell culture. The preferred interface comprises at least a part of the CH3 domain of an antibody constant domain. In this method, one or more small amino acid side chains from the interface of the first antibody molecule are replaced with larger side chains (e.g. tyrosine or tryptophan). Compensatory “cavities” of identical or similar size to the large side chain(s) are created on the interface of the second antibody molecule by replacing large amino acid side chains with smaller ones (e.g. alanine or threonine). This provides a mechanism for increasing the yield of the heterodimer over other unwanted end-products such as homodimers.

[0276] Bispecific antibodies include cross-linked or “heteroconjugate” antibodies. For example, one of the antibodies in the heteroconjugate can be coupled to avidin, the other to biotin. Such antibodies have, for example, been proposed to target immune system cells to unwanted cells (U.S. Pat. No. 4,676,980), and for treatment of HIV infection (WO 91/00360, WO 92/200373, and EP 03089). Heteroconjugate antibodies may be made using any convenient cross-linking methods. Suitable cross-linking agents are well known in the art, and are disclosed in U.S. Pat. No. 4,676,980, along with a number of cross-linking techniques.

[0277] Antibodies with more than two valencies are contemplated. For example, trispecific antibodies can be prepared. See, e.g., Tutt et al. J. Immunol. 147: 60 (1991), which is incorporated herein by reference.

[0278] The antibodies of the invention include derivatives that are otherwise modified, i.e., by the covalent attachment of any type of molecule to the antibody such that covalent attachment does not prevent the antibody from binding antigen and/or generating an anti-idiotypic response. For example, but not by way of limitation, the antibody derivatives include antibodies that have been modified, e.g., by glycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc. Any of numerous chemical modifications may be carried out by known techniques, including, but not limited to, specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. Additionally, the derivative may contain one or more non-classical amino acids.

[0279] For some uses, including in vivo use of antibodies in humans and in vitro detection assays, it may be preferable to use chimeric, humanized, or human antibodies. A chimeric antibody is a molecule in which different portions of the antibody are derived from different animal species, such as antibodies having a variable region derived from a murine monoclonal antibody and a constant region derived from a human immunoglobulin. Methods for producing chimeric antibodies are known in the art. See e.g., Morrison, Science, 229:1202, 1985; Oi et al., BioTechniques, 4:214 1986; Gillies et al., J. Immunol. Methods, 125:191-202, 1989; U.S. Pat. Nos. 5,807,715; 4,816,567; and 4,816,397, which are incorporated herein by reference in their entireties. Humanized antibodies are antibody molecules from non-human species that bind the desired antigen having one or more complementarity determining regions (CDRs) from the non-human species and framework regions and constant domains from a human immunoglobulin molecule. Often, framework residues in the human framework regions will be substituted with the corresponding residue from the CDR donor antibody to alter, preferably improve, antigen binding. These framework substitutions are identified by methods well known in the art, e.g., by modeling of the interactions of the CDR and framework residues to identify framework residues important for antigen binding and sequence comparison to identify unusual framework residues at particular positions. See, e.g., Queen et al., U.S. Pat. No. 5,585,089; Riechmann et al., Nature, 332:323, 1988, which are incorporated herein by reference in their entireties. Antibodies can be humanized using a variety of techniques known in the art including, for example, CDR-grafting (EP 239,400; PCT publication WO 91/09967; U.S. Pat. Nos. 5,225,539; 5,530,101 and 5,585,089), veneering or resurfacing (EP 592,106; EP 519,596; Padlan, Molecular Immunology, 28(4/5):489-498, 1991; Studnicka et al., Protein Engineering, 7(6):805-814, 1994; Roguska et al., Proc Natl. Acad. Sci. USA, 91:969-973, 1994), and chain shuffling (U.S. Pat. No. 5,565,332), all of which are hereby incorporated by reference in their entireties. Humanized antibodies may be generated using any of the methods disclosed in U.S. Pat. No. 5,693,762 (Protein Design Labs), U.S. Pat. No. 5,693,761, (Protein Design Labs) U.S. Pat. No. 5,585,089 (Protein Design Labs), U.S. Pat. No. 6,180,370 (Protein Design Labs), and U.S. Publication Nos. 20040049014, 200300229208, each of which is incorporated herein by reference in its entirety.

[0280] Completely human antibodies are particularly desirable for therapeutic treatment of human patients. Human antibodies can be made by a variety of methods known in the art including phage display methods described above using antibody libraries derived from human immunoglobulin sequences. See U.S. Pat. Nos. 4,444,887 and 4,716,111; and PCT publications WO 98/46645; WO 98/50433; WO 98/24893; WO 98/16654; WO 96/34096; WO 96/33735; and WO 91/10741, each of which is incorporated herein by reference in its entirety.

[0281] Human antibodies can also be produced using transgenic mice which are incapable of expressing functional endogenous immunoglobulins, but which can express human immunoglobulin genes. For an overview of this technology for producing human antibodies, see Lonberg and Huszar, Int. Rev. Immunol., 13:65-93, 1995. For a detailed discussion of this technology for producing human antibodies and human monoclonal antibodies and protocols for producing such antibodies, see, e.g., PCT publications WO 98/24893; WO 92/01047; WO 96/34096; WO 96/33735; European Patent No. 0 598 877; U.S. Pat. Nos. 5,413,923; 5,625,126; 5,633,425; 5,569,825; 5,661,016; 5,545,806; 5,814,318; 5,885,793; 5,916,771; and 5,939,598, which are incorporated by reference herein in their entireties. In addition, companies such as Abgenix, Inc. (Freemont, Calif.), Medarex (NJ) and Genpharm (San Jose, Calif.) can be engaged to provide human antibodies directed against a selected antigen using technology similar to that described above.

[0282] Completely human antibodies which recognize a selected epitope can be generated using a technique referred to as “guided selection.” In this approach a selected non-human monoclonal antibody, e.g., a mouse antibody, is used to guide the selection of a completely human antibody recognizing the same epitope (Jespers et al., Bio/technology, 12:899-903, 1988).

[0283] The invention encompasses engineering human or humanized therapeutic antibodies (e.g., tumor specific monoclonal antibodies) in the Fc region, by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue, which modification increases the affinity of the Fc region for FcγRIIIA and/or FcγRIIA. In another embodiment, the invention relates to engineering human or humanized therapeutic antibodies (e.g., tumor specific monoclonal antibodies) in the Fc region, by modification of at least one amino acid residue, which modification increases the affinity of the Fc region for FcγRIIIA and/or FcγRIIA and further decreases the affinity of the Fc region for FcγRIIB. The engineered therapeutic antibodies may further have an enhanced effector function, e.g., enhanced ADCC activity, phagocytosis activity, etc., as determined by standard assays known to those skilled in the art.

[0284] In a specific embodiment, the invention encompasses engineering a humanized monoclonal antibody specific for Her2/neu protooncogene (e.g., Ab4D5 humanized antibody as disclosed in Carter et al., 1992, Proc. Natl. Acad. Sci. USA 89:4285-9) by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fc region for FcγRIIIA and/or FcγRIIA. In another specific embodiment, modification of the humanized Her2/neu monoclonal antibody may also further decrease the affinity of the Fc region for FcγRIIB. In yet another specific embodiment, the engineered humanized monoclonal antibodies specific for Her2/neu may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein.

[0285] In another specific embodiment, the invention encompasses engineering a mouse human chimeric anti-CD20 monoclonal antibody, 2H7 by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fc region for FcγRIIIA and/or FcγRIIA. In another specific embodiment, modification of the anti-CD20 monoclonal antibody, 2H7 may also further decrease the affinity of the Fc region for FcγRIIB. In yet another specific embodiment, the engineered anti-CD20 monoclonal antibody, 2H7 may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein.

[0286] In certain embodiments, the invention encompasses engineering an antibody (or chimeric, humanized or other engineered versions thereof), comprising the heavy chain variable domain and/or light chain variable domain of the monoclonal antibody produced by clone 2B6, 3H7, 8B5.4.3, ID5, 2E1, 2H9, 2D11 or 1F2 having ATCC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively (deposited at ATCC, 10801 University Boulevard, Manassas, Va. 02209-2011, all of which are incorporated herein by reference). In a specific embodiment, the invention encompasses engineering a humanized antibody comprising the heavy chain variable and/or light chain variable domains of 2B6, 3H7 or 8B5.3.4. In another specific embodiment, the invention encompasses engineering a humanized antibody comprising the CDRs of 2B6, 3H7 or 8B5.3.4. In another specific embodiment, the invention encompasses engineering a humanized antibody comprising the heavy chain variable domain having the amino acid sequence of SEQ ID NO: 1, SEQ ID NO:2 or SEQ ID NO:3 and the light chain variable domain having the amino acid sequence of SEQ ID NO: 4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7 or SEQ ID NO: 8. In another specific embodiment, the invention encompasses engineering an anti-FcγRIIB antibody comprising the heavy chain variable domain having the amino acid sequence of SEQ ID NO:13 and the light chain variable domain having the amino acid sequence of SEQ ID NO:14. In another specific embodiment, the invention encompasses engineering a humanized anti-FcγRIIB antibody comprising the heavy chain variable domain having the amino acid sequence of SEQ ID NO:3 and the light chain variable domain having the amino acid sequence of SEQ ID NO:8. In another specific embodiment, the invention encompasses engineering a humanized anti-FcγRIIB antibody comprising the heavy chain variable domain having the amino acid sequence of SEQ ID NO:9 and the light chain variable domain having the amino acid sequence of SEQ ID NO:10.

[0287] In another specific embodiment, the invention encompasses engineering an anti-FcγRIIB antibody including but not limited to any of the antibodies disclosed in U.S. Provisional Application No. 60/403,266 filed on Aug. 12, 2002, U.S. application Ser. No. 10/643,857 filed on Aug. 14, 2003, U.S. Provisional Application No. 60/562,804 filed on Apr. 16, 2004, U.S. Provisional Application No. 60/582,044 filed on Jun. 21, 2004, U.S. Provisional Application No. 60/582,045 filed on Jun. 21, 2004, U.S. Provisional Application No. 60/636,663 filed on Dec. 15, 2004 and U.S. application Ser. No. 10/524,134 filed Feb. 11, 2005 by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fc region for FcγRIIIA and/or FcγRIIA. In another specific embodiment, the invention encompasses engineering a humanized anti-FcγRIIB antibody including but not limited to any of the antibodies disclosed in U.S. Provisional Application No. 60/569,882 filed on May 10, 2004, U.S. Provisional Application No. 60/582,043 filed on Jun. 21, 2004 and U.S. application Ser. No. 11/126,978, filed on May 10, 2005 by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fc region for FcγRIIIA and/or FcγRIIA. Each of the above mentioned applications is incorporated herein by reference in its entirety. Examples of anti-FcγRIIB antibodies, which may or may not be humanized, that may be engineered in accordance with the methods of the invention are 2B6 monoclonal antibody having ATCC accession number PTA-4591 and 3H7 having ATCC accession number PTA-4592, D5 monoclonal antibody having ATCC accession number PTA-5958, 1F2 monoclonal antibody having ATCC accession number PTA-5959, 2D11 monoclonal antibody having ATCC accession number PTA-5960, 2 μl monoclonal antibody having ATCC accession number PTA-5961, 8B5.3.4 having ATCC accession number PTA-7610, and 2H9 monoclonal antibody having ATCC accession number PTA-5962 (all deposited at 10801 University Boulevard, Manassas, Va. 02209-2011), which are incorporated herein by reference. In another specific embodiment, modification of the anti-FcγRIIB antibody may also further decrease the affinity of the Fc region for FcγRIIB. In yet another specific embodiment, the engineered anti-FcγRIIB antibody may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein.

[0288] In a specific embodiment, the invention encompasses engineering an anti-FcγRIIB antibody according to methods of the present invention that comprises one or more complementarily determining regions (CDRs), preferably all 6 CDRs, of the antibody produced by clone 2B6, 3H7, or 8B5.3.4 with ATCC accession numbers PTA-4591, PTA-4592, and PTA-7610, respectively (e.g., the heavy chain CDR3). In a specific embodiment, an anti-FcγRIIB antibody engineered according to methods of the invention comprises one or more complementarily determining regions (CDRs), preferably all 6 CDRs, of the antibody produced by clone 1D5, 2E1, 2H9, 2D11, and 1F2 having ATCC Accession numbers, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively (e.g., the heavy chain CDR3). In another embodiment, an anti-FcγRIIB antibody engineered according to methods of the invention binds to the same epitope as the mouse monoclonal antibody produced from clone 2B6, 3H7, or 8B5.3.4 with ATCC accession numbers PTA-4591, PTA-4592, and PTA-7610, respectively and/or competes with the mouse monoclonal antibody produced from clone 2B6, 3H7, or 8B5.3.4 with ATCC accession numbers PTA-4591, PTA-4592, and PTA-7610, respectively as determined, e.g., in an ELISA assay or other appropriate competitive immunoassay, and also binds FcγRIIB with a greater affinity than said antibody or a fragment thereof binds FcγRIIA. In another embodiment, an anti-FcγRIIB antibody engineered according to methods of the invention binds to the same epitope as the mouse monoclonal antibody produced from clone 1D5, 2E1, 2H9, 2D11, and 1F2 having ATCC Accession numbers, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively, and/or competes with the mouse monoclonal antibody produced from clone 1D5, 2E1, 29, 2D11, and 1F2 having ATCC Accession numbers, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively, as determined, e.g., in an ELISA assay or other appropriate competitive immunoassay, and also binds FcγRIIB, via its variable region, with a greater affinity than said antibody or a fragment thereof binds FcγRIIA.

[0289] The present invention also encompasses engineering an anti-FcγRIIB antibody comprising a heavy chain variable domain and/or light chain variable domain amino acid sequence that is at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the amino acid sequence of the heavy chain variable domain and/or light chain variable domain of the mouse monoclonal antibody produced by clone 2B6, 3H7, 8B5.3.4, 1D5, 2E1, 2H9, 2D11, or 1F2 having ATCC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively. The present invention further encompasses the engineering of anti-FcγRIIB antibodies comprising an amino acid sequence of one or more CDRs that is at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the amino acid sequence of one or more CDRs of the mouse monoclonal antibody produced by clone 2B6, 3H7, 8B5.3.4, 1D5, 2E1, 2H9, 2D11, or 1F2 having ATCC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively. The determination of percent identity of two amino acid sequences can be determined by any method known to one skilled in the art, including BLAST protein searches.

[0290] The present invention also encompasses the engineering of one or more anti-FcγRIIB antibodies comprising one or more variable domains encoded by a nucleotide sequence that hybridizes to the nucleotide sequence of one or more variable domains of a mouse monoclonal antibody produced by clone 2B6, 3H7, 8B5.3.4, 1D5, 2E1, 2H9, 2D11, or 1F2 having ATCC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively, under stringent conditions. In a preferred embodiment, the invention encompasses engineering one or more anti-FcγRIIB antibodies comprising a variable light chain and/or variable heavy chain domain encoded by a nucleotide sequence that hybridizes under stringent conditions to the nucleotide sequence of the variable light chain and/or variable heavy chain domain of the mouse monoclonal antibody produced by clone 2B6, 3H7, 8B5.3.4, 1D5, 2E1, 2H9, 2D11, or 1F2 having ATCC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively, under stringent conditions. In another preferred embodiment, the invention provides engineering anti-FcγRIIB antibodies comprising one or more CDRs encoded by a nucleotide sequence that hybridizes under stringent conditions to the nucleotide sequence of one or more CDRs of the mouse monoclonal antibody produced by clone 2B6, 3H7, 8B5.3.4, 1D5, 2E1, 2H9, 2D11, or 1F2 having ATCC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively. Stringent hybridization conditions include, but are not limited to, hybridization to filter-bound DNA in 6× sodium chloride/sodium citrate (SSC) at about 45° C. followed by one or more washes in 0.2×SSC/0.1% SDS at about 50-65° C., highly stringent conditions such as hybridization to filter-bound DNA in 6×SSC at about 45° C. followed by one or more washes in 0.1×SSC/0.2% SDS at about 60° C., or any other stringent hybridization conditions known to those skilled in the art (see, for example, Ausubel, F. M. et al., eds. 1989 Current Protocols in Molecular Biology, vol. 1, Green Publishing Associates, Inc. and John Wiley and Sons, Inc., NY at pages 6.3.1 to 6.3.6 and 2.10.3, incorporated herein by reference).

[0291] In a preferred embodiment, the engineered antibodies of the invention are humanized by any method known in the art or described herein and/or comprise the CDR regions of a humanized FcγRIIB specific antibody or humanized CD20 specific antibody, wherein said CDRs are derived from a murine antibody specific for FcγRIIB or CD20, respectively. In some embodiments, the humanized antibodies described herein comprise alterations, including but not limited to amino acid deletions, insertions, modifications, of the acceptor antibody, i.e., human, heavy and/or light chain variable domain framework regions that are necessary for retaining binding specificity of the donor monoclonal antibody. In some embodiments, the framework regions of the humanized antibodies described herein do not necessarily consist of the precise amino acid sequence of the framework region of a natural occurring human antibody variable region, but contains various alterations, including but not limited to amino acid deletions, insertions, modifications that alter the property of the humanized antibody, for example, improve the binding properties of a humanized antibody variable region specific for the same target as the murine FcγRIIB or CD20 specific antibody. In most preferred embodiments, a minimal number of alterations are made to the framework region in order to avoid large-scale introductions of non-human framework residues and to ensure minimal immunogenicity of the humanized antibody of the invention in humans. The donor monoclonal antibody is preferably a monoclonal antibody produced by clones 2B6, 3H7, 8B5.3.4, 1D5, 2E1, 2H9, 2D11, or 1F2 (having ATCC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively) which bind FcγRIIB, or the monoclonal antibody is a CD20 antibody, such as rituximab or 2H7.

[0292] In a specific embodiment, the invention encompasses engineering a CDR-grafted antibody that comprises a heavy chain variable region domain comprising framework residues of the recipient antibody and residues from the donor monoclonal antibody, which specifically binds FcγRIIB, e.g., monoclonal antibody produced from clones 2B6, 3H7, 8B5.3.4, 1D5, 2E1, 2H9, 2D11, or 1F2 having ATCC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively. In another specific embodiment, the invention encompasses engineering a CDR-grafted antibody that comprises a light chain variable region domain comprising framework residues of the recipient antibody and residues from the donor monoclonal antibody, which specifically binds FcγRIIB, e.g., monoclonal antibody produced from clones 2B6, 3H7, 8B5.3.4, 1D5, 2E1, 2H9, 2D11, or 1F2.

[0293] Preferably the FcγRIIB humanized antibodies bind the extracellular domain of native human FcγRIIB. The humanized anti-FcγRIIB antibodies of the combinations can have a heavy chain variable region comprising the amino acid sequence of CDR1 (SEQ ID NO: 15 or SEQ ID NO: 16) and/or CDR2 (SEQ ID NO:17 or SEQ ID NO:18) and/or CDR3 (SEQ ID NO: 19 or SEQ ID NO:20) and/or a light chain variable region comprising the amino acid sequence of CDR1 (SEQ ID NO:21 or SEQ ID NO:22) and/or a CDR2 (SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, or SEQ ID NO:26) and/or CDR3 (SEQ ID NO:27 or SEQ ID NO:28).

[0294] In a specific embodiment, the invention encompasses the engineering of a humanized anti-FcγRIIB antibody with the heavy chain variable domain having the amino acid sequence of SEQ ID NO:1, SEQ ID NO:2, or SEQ ID NO:3 and a light chain variable domain having the amino acid sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6; SEQ ID NO:7 or SEQ ID NO:8.

[0295] In one specific embodiment, the invention encompasses engineering a humanized anti-FcγRIIB antibody, wherein the VH region of the FcγRIIB antibody consists of the FR segments from the human germline VH segment VH1-18 (Matsuda et al., 1998, J. Exp. Med. 188:2151062) and JH6 (Ravetch et al., 1981, Cell 27(3 Pt. 2): 583-91), and one or more CDR regions of a 2B6 VH, having the amino acid sequence of SEQ ID NO: 1, SEQ ID NO:17, or SEQ ID NO:19. In one embodiment, the 2B6 VH has the amino acid sequence of SEQ ID NO:1, SEQ ID NO:3, or SEQ ID NO:29. In another specific embodiment, the humanized anti-FcγRIIB antibody further comprises a VL region, which consists of the FR segments of the human germline VL segment VK-A26 (Lautner-Rieske et al., 1992, Eur. J. Immunol. 22:1023-1029) and JK4 (Hieter et al., 1982, J. Biol. Chem. 257:1516-22), and one or more CDR regions of a 2B6VL, having the amino acid sequence of SEQ ID NO:21, SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, and SEQ ID NO:27. In one embodiment, the 2B6 VL has the amino acid sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6; SEQ ID NO:7, SEQ ID NO:8, or SEQ ID NO:30, and optionally in combination with one of the above-referenced 2B6 VH.

[0296] In some embodiments, the anti-FcγRIIB antibody engineered in accordance with the methods of the invention has a VH chain and/or a VH domain comprising the amino acid sequence (H2B6VH-3):

(SEQ ID NO:3)
QVQLVQSGAEVKKPGASVKVSCKASGYTFTNYWIHWVRQAPGQGLEWIGV
IDPSDTYPNYNKKFKGRVTMTVDTSTSTAYMELRSLRSDDTAVYYCARNG
DSDYYSGMDYWGQGTTVTVSS.

[0297] In some embodiments, the anti-FcγRIIB antibody engineered in accordance with the methods of the invention has a VL chain and/or VL domain comprising the amino acid sequence (H2B6VL-5):

(SEQ ID NO:8)
EIVLTQSPDFQSVTPKEKVTFTCRTSQSIGTNIHWYQQKPDQSPKLLIKE
VSESISGVPSRFSGSGSGTDFTLTTNSLEAEDAATYYCQQSNTWPFTFGG
GTKVEIK.

[0298] In some embodiments, the anti-FcγRIIB antibody engineered in accordance with the methods of the invention has a VH chain and/or VH domain comprising the amino acid sequence (H2B6VH-3):

(SEQ ID NO:3)
QVQLVQSGAEVKKPGASVKVSCKASGYTFTNYWIHWVRQAPGQGLEWIGV
IDPSDTYPNYNKKFKGRVTMTVDTSTSTAYMELRSLRSDDTAVYYCARNG
DSDYYSGMDYWGQGTTVTVSS,

[0299] and a VL chain and/or VL domain comprising the amino acid sequence (H2B6VL-5):

(SEQ ID NO:8)
EIVLTQSPDFQSVTPKEKVTFTCRTSQSIGTNIHWYQQKPDQSPKLLIKE
VSESISGVPSRFSGSGSGTDFTLTTNSLEAEDAATYYCQQSNTWPFTFGG
GTKVEIK.

[0300] In some embodiments, the anti-FcγRIIB antibody engineered in accordance with the methods of the invention has a VH domain and/or VH chain comprising the amino acid sequence (8B5.3.4 VH, see FIG. 2):

(SEQ ID NO:9)
EVKLEESGGGLVQPGGSMKLSCEASGFTFSDAWMDWVRQSPEKGLEWVAE
TRNKAKNHATYYAESVIGRFTISRDDSKSSVYLQMNSLRAEDTGIYYCGA
LGLDYWGQGTTLTVSS.

[0301] In some embodiments, the anti-FcγRIIB antibody engineered in accordance with the methods of the invention has a VL domain and/or VL chain comprising the amino acid sequence (8B5.3.4 VL, see FIG. 1):

(SEQ ID NO:10)
DIQMTQSPSSLLAALGERVSLTCRASQEISGYLSWLQQKPDGTIKRLIYA
ASTLDSGVPKRFSGSESGSDYSLTISSLESEDFADYYCLQYFSYPLTFGA
GTKLELK.

[0302] In some embodiments, the anti-FcγRIIB antibody engineered in accordance with the methods of the invention has a VH domain and/or VH chain comprising the amino acid sequence (8B5.3.4 VH):

(SEQ ID NO:9, see FIG. 2)
EVKLEESGGGLVQPGGSMKLSCEASGFTFSDAWMDWVRQSPEKGLEWVAE
TRNKAKNHATYYAESVIGRFTISRDDSKSSVYLQMNSLRAEDTGIYYCGA
LGLDYWGQGTTLTVSS,

[0303] and a VL domain and/or VL chain comprising the amino acid sequence (8B5.3.4 VL, see FIG. 1):

(SEQ ID NO:10)
DIQMTQSPSSLLAALGERVSLTCRASQEISGYLSWLQQKPDGTIKRLIYA
ASTLDSGVPKRFSGSESGSDYSLTISSLESEDFADYYCLQYFSYPLTFGA
GTKLELK.

[0304] In another specific embodiment, the anti-FcγRIIB antibody engineered in accordance with the methods of the invention is a humanized 3H7 antibody, wherein the FcγRIIB VH region consists of the FR segments from a human germline VH segment and the CDR regions of the 3H7 VH, having the amino acid sequence of SEQ ID NO: 37. In another specific embodiment, the humanized 3H7 antibody further comprises a VL region, which consists of the FR segments of a human germline VL segment and the CDR regions of 3H7VL, having the amino acid sequence of SEQ ID NO:7.

[0305] In particular, the invention encompasses the engineering of an anti-FcγRIIB antibody wherein the antibody immunospecifically binds to an extracellular domain of native human FcγRIIB, said FcγRIIB antibody comprising (or alternatively, consisting of) CDR sequences of 2B6, 3H7, or 8B5.3.4 in any of the following combinations: a VH CDR1 and a VL CDR1; a VH CDR1 and a VL CDR2; a VH CDR1 and a VL CDR3; a VH CDR2 and a VL CDR1; VH CDR2 and VL CDR2; a VH CDR2 and a VL CDR3; a VH CDR3 and a VH CDR1; a VH CDR3 and a VL CDR2; a VH CDR3 and a VL CDR3; a VH1 CDR1, a VH CDR2 and a VL CDR1; a VH CDR1, a VH CDR2 and a VL CDR2; a VH CDR1, a VH CDR2 and a VL CDR3; a VH CDR2, a VH CDR3 and a VL CDR1, a VH CDR2, a VH CDR3 and a VL CDR2; a VH CDR2, a VH CDR2 and a VL CDR3; a VH CDR1, a VL CDR1 and a VL CDR2; a VH CDR1, a VL CDR1 and a VL CDR3; a VH CDR2, a VL CDR1 and a VL CDR2; a VH CDR2, a VL CDR1 and a VL CDR3; a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR1, a VH CDR2, a VH CDR3 and a VL CDR1; a VH CDR1, a VH CDR2, a VH CDR3 and a VL CDR2; a VH CDR1, a VH CDR2, a VH CDR3 and a VL CDR3; a VH CDR1, a VH CDR2, a VL CDR1 and a VL CDR2; a VH CDR1, a VH CDR2, a VL CDR1 and a VL CDR3; a VH CDR1, a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR1, a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR2, a VH CDR3, a VL CDR2 and a VL CDR3; a VH CDR1, a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR1, a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR1, a VH CDR2, a VL CDR1, a VL CDR2, and a VL CDR3; a VH CDR1, a VH CDR3, a VL CDR1, a VL CDR2, and a VL CDR3; a VH CDR2, a VH CDR3, a VL CDR1, a VL CDR2, and a VL CDR3; or any combination thereof of the VH CDRs and VL CDRs disclosed herein.

[0306] In a specific embodiment, the anti-FcγRIIB monoclonal antibody comprises a modification at position 334 with glutamic acid, at position 359 with asparagine, and at position 366 with serine (MgFc13); or a substitution at position 316 with aspartic acid, at position 378 with valine, and at position 399 with glutamic acid (MgFc27); or a substitution at position 243 with isoleucine, at position 379 with leucine, and at position 420 with valine (MgFc29); or a substitution at position 392 with threonine and at position 396 with leucine (MgFc38); or a substitution at position 221 with glutamic acid, at position 270 with glutamic acid, at position 308 with alanine, at position 311 with histidine, at position 396 with leucine, and at position 402 with aspartic (MgFc42); or a substitution at position 410 with histidine, and at position 396 with leucine (MgFc53); or a substitution at position 243 with leucine, at position 305 with isoleucine, at position 378 with aspartic acid, at position 404 with serine, and at position 396 with leucine (MgFc54); or a substitution at position 255 with isoleucine, and at position 396 with leucine (MgFc55); or a substitution at position 370 with glutamic acid, and at position 396 with leucine (MgFc59); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine (MgFc88); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine (MgFc88A); or a substitution at position 234 with leucine, at position 292 with proline, and at position 300 with leucine (MgFc155); or a substitution at position 243 with leucine, at position 292 with proline, and at position 300 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, and at position 396 with leucine; or a substitution at position 243 with leucine, and at position 292 with proline; or a substitution at position 243 with leucine; or a substitution at position 273 with phenylalanine (See Tables 5 & 6).

[0307] 5.1.1 Polypeptide and Antibody Conjugates

[0308] Molecules of the invention (i.e., polypeptides, antibodies) comprising variant Fc regions may be recombinantly fused or chemically conjugated (including both covalently and non-covalently conjugations) to heterologous polypeptides (i.e., an unrelated polypeptide; or portion thereof, preferably at least 10, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90 or at least 100 amino acids of the polypeptide) to generate fusion proteins. The fusion does not necessarily need to be direct, but may occur through linker sequences.

[0309] Further, molecules of the invention (i.e., polypeptides, antibodies) comprising variant Fc regions may be conjugated to a therapeutic agent or a drug moiety that modifies a given biological response. Therapeutic agents or drug moieties are not to be construed as limited to classical chemical therapeutic agents. For example, the drug moiety may be a protein or polypeptide possessing a desired biological activity. Such proteins may include, for example, a toxin such as abrin, ricin A, pseudomonas exotoxin (i.e., PE-40), or diphtheria toxin, ricin, gelonin, and pokeweed antiviral protein, a protein such as tumor necrosis factor, interferons including, but not limited to, α-interferon (IFN-α), α-interferon (IFN-β), nerve growth factor (NGF), platelet derived growth factor (PDGF), tissue plasminogen activator (TPA), an apoptotic agent (e.g., TNF-α, TNF-β, AIM I as disclosed in PCT Publication No. WO 97/33899), AIM II (see, PCT Publication No. WO 97/34911), Fas Ligand (Takahashi et al., J. Immunol., 6:1567-1574, 1994), and VEGI (PCT Publication No. WO 99/23105), a thrombotic agent or an anti-angiogenic agent (e.g., angiostatin or endostatin), or a biological response modifier such as, for example, a lymphokine (e.g., interleukin-1 (“IL-1”), interleukin-2 (“IL-2”), interleukin-6 (“IL-6”), granulocyte macrophage colony stimulating factor (“GM-CSF”), and granulocyte colony stimulating factor (“G-CSF”), macrophage colony stimulating factor, (“M-CSF”), or a growth factor (e.g., growth hormone (“GH”); proteases, or ribonucleases.

[0310] Molecules of the invention (i.e., polypeptides, antibodies) can be fused to marker sequences, such as a peptide to facilitate purification. In preferred embodiments, the marker amino acid sequence is a hexa-histidine peptide, such as the tag provided in a pQE vector (QIAGEN, Inc., 9259 Eton Avenue, Chatsworth, Calif., 91311), among others, many of which are commercially available. As described in Gentz et al., 1989, Proc. Natl. Acad. Sci. USA, 86:821-824, for instance, hexa-histidine provides for convenient purification of the fusion protein. Other peptide tags useful for purification include, but are not limited to, the hemagglutinin “HA” tag, which corresponds to an epitope derived from the influenza hemagglutinin protein (Wilson et al., Cell, 37:767 1984) and the “flag” tag (Knappik et al., Biotechniques, 17(4):754-761, 1994).

[0311] Additional fusion proteins may be generated through the techniques of gene-shuffling, motif-shuffling, exon-shuffling, and/or codon-shuffling (collectively referred to as “DNA shuffling”). DNA shuffling may be employed to alter the activities of molecules of the invention (e.g., antibodies with higher affinities and lower dissociation rates). See, generally, U.S. Pat. Nos. 5,605,793; 5,811,238; 5,830,721; 5,834,252; and 5,837,458, and Patten et al., 1997, Curr. Opinion Biotechnol. 8:724-33; Harayama, 1998, Trends Biotechnol. 16:76; Hansson, et al., 1999, J. Mol. Biol. 287:265; and Lorenzo and Blasco, 1998, BioTechniques 24:308 (each of these patents and publications are hereby incorporated by reference in its entirety). Molecules of the invention comprising variant Fc regions, or the nucleic acids encoding the molecules of the invention, may be further altered by being subjected to random mutagenesis by error-prone PCR, random nucleotide insertion or other methods prior to recombination. One or more portions of a polynucleotide encoding a molecule of the invention, may be recombined with one or more components, motifs, sections, parts, domains, fragments, etc. of one or more heterologous molecules.

[0312] The present invention also encompasses molecules of the invention comprising variant Fc regions (i.e., antibodies, polypeptides) conjugated to a diagnostic or therapeutic agent or any other molecule for which serum half-life is desired to be increased and/or targeted to a particular subset of cells. The molecules of the invention can be used diagnostically to, for example, monitor the development or progression of a disease, disorder or infection as part of a clinical testing procedure to, e.g., determine the efficacy of a given treatment regimen. Detection can be facilitated by coupling the molecules of the invention to a detectable substance. Examples of detectable substances include various enzymes, prosthetic groups, fluorescent materials, luminescent materials, bioluminescent materials, radioactive materials, positron emitting metals, and nonradioactive paramagnetic metal ions. The detectable substance may be coupled or conjugated either directly to the molecules of the invention or indirectly, through an intermediate (such as, for example, a linker known in the art) using techniques known in the art. See, for example, U.S. Pat. No. 4,741,900 for metal ions which can be conjugated to antibodies for use as diagnostics according to the present invention. Such diagnosis and detection can be accomplished by coupling the molecules of the invention to detectable substances including, but not limited to, various enzymes, enzymes including, but not limited to, horseradish peroxidase, alkaline phosphatase, beta-galactosidase, or acetylcholinesterase; prosthetic group complexes such as, but not limited to, streptavidin/biotin and avidin/biotin; fluorescent materials such as, but not limited to, umbelliferone, fluorescein, fluorescein isothiocyanate, rhodamine, dichlorotriazinylamine fluorescein, dansyl chloride or phycoerythrin; luminescent material such as, but not limited to, luminol; bioluminescent materials such as, but not limited to, luciferase, luciferin, and aequorin; radioactive material such as, but not limited to, bismuth (²¹³Bi), carbon (¹⁴C), chromium (⁵¹Cr), cobalt (⁵⁷Co), fluorine (⁶⁸F), gadolinium (¹⁵³Gd, ¹⁵⁹Gd), gallium (⁶⁸ Ga, ⁶⁷Ga), germanium (⁶⁸Ge), holmium (¹⁶⁶Ho), indium (¹¹⁵In, ¹¹³In, ¹¹²In, ¹¹¹In), iodine (¹³¹, ¹²⁵I, ¹²³I, ¹²¹I), lanthanium (¹⁴⁰La), lutetium (¹⁷⁷Lu), manganese (⁵⁴Mn), molybdenum (⁹⁹Mo), palladium (¹⁰³Pd), phosphorous (³²P), praseodymium (¹⁴²Pr), promethium (¹⁴⁹ Pm), rhenium (¹⁸⁶Re, ¹⁸⁸Re), rhodium (¹⁰⁵Rh), ruthemium (⁹⁷Ru), samarium (¹⁵³Sm), scandium (⁴⁷Sc), selenium (⁷⁵Se), strontium (⁸⁵Sr), sulfur (³⁵S), technetium (⁹⁹Tc), thallium (²⁰¹Ti), tin (¹¹³Sn, ¹¹⁷Sn), tritium (³H), xenon (¹³³Xe), ytterbium (¹⁶⁹Yb, ¹⁷⁵Yb), yttrium (⁹⁰Y), zinc (⁶⁵Zn); positron emitting metals using various positron emission tomographies, and nonradioactive paramagnetic metal ions.

[0313] Molecules of the invention (i.e., antibodies, polypeptides) comprising a variant Fc region may be conjugated to a therapeutic moiety such as a cytotoxin (e.g., a cytostatic or cytocidal agent), a therapeutic agent or a radioactive element (e.g., alpha-emitters, gamma-emitters, etc.). Cytotoxins or cytotoxic agents include any agent that is detrimental to cells. Examples include paclitaxol, cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin, etoposide, tenoposide, vincristine, vinblastine, colchicin, doxorubicin, daunorubicin, dihydroxy anthracin dione, mitoxantrone, mithramycin, actinomycin D, 1-dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine, propranolol, and puromycin and analogs or homologs thereof. Therapeutic agents include, but are not limited to, antimetabolites (e.g., methotrexate, 6-mercaptopurine, 6-thioguanine, cytarabine, 5-fluorouracil decarbazine), alkylating agents (e.g., mechlorethamine, thioepa chlorambucil, melphalan, carmustine (BSNU) and lomustine (CCNU), cyclothosphamide, busulfan, dibromomannitol, streptozotocin, mitomycin C, and cisdichlorodiamine platinum (II) (DDP) cisplatin), anthracyclines (e.g., daunorubicin (formerly daunomycin) and doxorubicin), antibiotics (e.g., dactinomycin (formerly actinomycin), bleomycin, mithramycin, and anthramycin (AMC), and anti-mitotic agents (e.g., vincristine and vinblastine).

[0314] Moreover, a molecule of the invention can be conjugated to therapeutic moieties such as a radioactive materials or macrocyclic chelators useful for conjugating radiometal ions (see above for examples of radioactive materials). In certain embodiments, the macrocyclic chelator is 1,4,7,10-tetraazacyclododecane-N,N′,N″,N′″-tetraacetic acid (DOTA) which can be attached to the antibody via a linker molecule. Such linker molecules are commonly known in the art and described in Denardo et al., 1998, Clin Cancer Res. 4:2483-90; Peterson et al., 1999, Bioconjug. Chem. 10:553; and Zimmerman et al., 1999, Nucl. Med. Biol. 26:943-50 each of which is incorporated herein by reference in their entireties.

[0315] Techniques for conjugating such therapeutic moieties to antibodies are well known; see, e.g., Arnon et al., “Monoclonal Antibodies For Immunotargeting Of Drugs In Cancer Therapy”, in Monoclonal Antibodies And Cancer Therapy, Reisfeld et al. (eds.), 1985, pp. 243-56, Alan R. Liss, Inc.); Hellstrom et al., “Antibodies For Drug Delivery”, in Controlled Drug Delivery (2nd Ed.), Robinson et al. (eds.), 1987, pp. 623-53, Marcel Dekker, Inc.); Thorpe, “Antibody Carriers Of Cytotoxic Agents In Cancer Therapy: A Review”, in Monoclonal Antibodies '84: Biological And Clinical Applications, Pinchera et al. (eds.), 1985, pp. 475-506); “Analysis, Results, And Future Prospective Of The Therapeutic Use Of Radiolabeled Antibody In Cancer Therapy”, in Monoclonal Antibodies For Cancer Detection And Therapy, Baldwin et al. (eds.), 1985, pp. 303-16, Academic Press; and Thorpe et al., Immunol. Rev., 62:119-58, 1982.

[0316] In one embodiment, where the molecule of the invention is an antibody comprising a variant Fc region, it can be administered with or without a therapeutic moiety conjugated to it, administered alone, or in combination with cytotoxic factor(s) and/or cytokine(s) for use as a therapeutic treatment. Alternatively, an antibody of the invention can be conjugated to a second antibody to form an antibody heteroconjugate as described by Segal in U.S. Pat. No. 4,676,980, which is incorporated herein by reference in its entirety. Antibodies of the invention may also be attached to solid supports, which are particularly useful for immunoassays or purification of the target antigen. Such solid supports include, but are not limited to, glass, cellulose, polyacrylamide, nylon, polystyrene, polyvinyl chloride or polypropylene.

[0317] 5.2 Screening of Molecules with Variant Fc Regions for Enhanced FcγRIII Binding and Characterization of Same

[0318] In preferred embodiments, screening and identifying molecules comprising variant Fc regions with altered FcγR affinities (e.g., enhanced FcγRIIIA affinity) are done using the yeast display technology as described herein in combination with one or more biochemical based assays, preferably in a high throughput manner. The one or more biochemical assays can be any assay known in the art for identifying Fc-FcγR interaction, i.e., specific binding of an Fc region to an FcγR, including, but not limited to, an ELISA assay, surface plasmon resonance assays, immunoprecipitation assay, affinity chromatography, and equilibrium dialysis. In some embodiments, screening and identifying molecules comprising variant Fc regions with altered FcγR affinities (e.g., enhanced FcγRIIIA affinity) are done using the yeast display technology as described herein in combination with one or more functional based assays, preferably in a high throughput manner. The functional based assays can be any assay known in the art for characterizing one or more FcγR mediated effector cell functions such as those described herein in Section 5.2.7. Non-limiting examples of effector cell functions that can be used in accordance with the methods of the invention, include but are not limited to, antibody-dependent cell mediated cytotoxicity (ADCC), antibody-dependent phagocytosis, phagocytosis, opsonization, opsonophagocytosis, cell binding, rosetting, C1q binding, and complement dependent cell mediated cytotoxicity. In some embodiments, screening and identifying molecules comprising variant Fc regions with altered FcγR affinities (e.g., enhanced FcγRIIIA affinity) are done using the yeast display technology as described herein in combination with one or more biochemical based assays in combination or in parallel with one or more functional based assays, preferably in a high throughput manner.

[0319] The term “specific binding” of an Fc region to an FcγR refers to an interaction of the Fc region and a particular FcγR which has an affinity constant of at least about 150 nM, in the case of monomeric FcγRIIIA and at least about 60 nM in the case of dimeric FcγRIIB as determined using, for example, an ELISA or surface plasmon resonance assay (e.g., a BIAcore™). The affinity constant of an Fc region for monomeric FcγRIIIA may be 150 nM, 200 nM or 300 nM. The affinity constant of an Fc region for dimeric FcγRIIB may be 60 nM, 80 nM, 90 nM, or 100 nM. Dimeric FcγRIIB for use in the methods of the invention may be generated using methods known to one skilled in the art. Typically, the extracellular region of FcγRIIB is covalently linked to a heterologous polypeptide which is capable of dimerization, so that the resulting fusion protein is a dimer, e.g., see, U.S. Application No. 60/439,709 filed on Jan. 13, 2003 (Attorney Docket No. 11183-005-888), which is incorporated herein by reference in its entirety. A specific interaction generally is stable under physiological conditions, including, for example, conditions that occur in a living individual such as a human or other vertebrate or invertebrate, as well as conditions that occur in a cell culture such conditions as used for maintaining and culturing mammalian cells or cells from another vertebrate organism or an invertebrate organism.

[0320] In a specific embodiment, screening for and identifying molecules comprising variant Fc regions and altered FcγR affinities comprise: displaying the molecule comprising a variant Fc region on the yeast surface; and characterizing the binding of the molecule comprising the variant Fc region to a FcγR (one or more), using a biochemical assay for determining Fc-FcγR interaction, preferably, an ELISA based assay. Once the molecule comprising a variant Fc region has been characterized for its interaction with one or more FcγRs and determined to have an altered affinity for one or more FcγRs, by at least one biochemical based assay, e.g., an ELISA assay, the molecule maybe engineered into a complete immunoglobulin, using standard recombinant DNA technology methods known in the art, and the immunoglobulin comprising the variant Fc region expressed in mammalian cells for further biochemical characterization. The immunoglobulin into which a variant Fc region of the invention is introduced (e.g., replacing the Fc region of the immunoglobulin) can be any immunoglobulin including, but not limited to, polyclonal antibodies, monoclonal antibodies, bispecific antibodies, multi-specific antibodies, humanized antibodies, and chimeric antibodies. In preferred embodiments, a variant Fc region is introduced into an immunoglobulin specific for a cell surface receptor, a tumor antigen, or a cancer antigen. The immunoglobulin into which a variant Fc region of the invention is introduced may specifically bind a cancer or tumor antigen for example, including, but not limited to, KS ¼ pan-carcinoma antigen (Perez and Walker, 1990, J. Immunol. 142: 3662-3667; Bumal, 1988, Hybridoma 7(4): 407-415), ovarian carcinoma antigen (CA125) (Yu et al., 1991, Cancer Res. 51(2): 468-475), prostatic acid phosphate (Tailor et al., 1990, Nucl. Acids Res. 18(16): 4928), prostate specific antigen (Henttu and Vihko, 1989, Biochem. Biophys. Res. Comm. 160(2): 903-910; Israeli et al., 1993, Cancer Res. 53: 227-230), melanoma-associated antigen p97 (Estin et al., 1989, J. Natl. Cancer Instit. 81(6): 445-446), melanoma antigen gp75 (Vijayasardahl et al., 1990, J. Exp. Med. 171(4): 1375-1380), high molecular weight melanoma antigen (HMW-MAA) (Natali et al., 1987, Cancer 59: 55-63; Mittelman et al., 1990, J. Clin. Invest. 86: 2136-2144), prostate specific membrane antigen, carcinoembryonic antigen (CEA) (Foon et al., 1994, Proc. Am. Soc. Clin. Oncol. 13: 294), polymorphic epithelial mucin antigen, human milk fat globule antigen, colorectal tumor-associated antigens such as: CEA, TAG-72 (Yokata et al., 1992, Cancer Res. 52: 3402-3408), CO17-1A (Ragnhammar et al., 1993, Int. J. Cancer 53: 751-758); GICA 19-9 (Herlyn et al., 1982, J. Clin. Immunol. 2: 135), CTA-1 and LEA, Burkitt's lymphoma antigen-38.13, CD19 (Ghetie et al., 1994, Blood 83: 1329-1336), human B-lymphoma antigen-CD20 (Reff et al., 1994, Blood 83:435-445), CD33 (Sgouros et al., 1993, J. Nucl. Med. 34:422-430), melanoma specific antigens such as ganglioside GD2 (Saleh et al., 1993, J. Immunol., 151, 3390-3398), ganglioside GD3 (Shitara et al., 1993, Cancer Immunol. Immunother. 36:373-380), ganglioside GM2 (Livingston et al., 1994, J. Clin. Oncol. 12: 1036-1044), ganglioside GM3 (Hoon et al., 1993, Cancer Res. 53: 5244-5250), tumor-specific transplantation type of cell-surface antigen (TSTA) such as virally-induced tumor antigens including T-antigen DNA tumor viruses and Envelope antigens of RNA tumor viruses, oncofetal antigen-alpha-fetoprotein such as CEA of colon, bladder tumor oncofetal antigen (Hellstrom et al., 1985, Cancer. Res. 45:2210-2188), differentiation antigen such as human lung carcinoma antigen L6, L20 (Hellstrom et al., 1986, Cancer Res. 46: 3917-3923), antigens of fibrosarcoma, human leukemia T cell antigen-Gp37 (Bhattacharya-Chatterjee et al., 1988, J. of Immun. 141:1398-1403), neoglycoprotein, sphingolipids, breast cancer antigen such as EGFR (Epidermal growth factor receptor), HER2 antigen (p185^HER2), polymorphic epithelial mucin (PEM) (Hilkens et al., 1992, Trends in Bio. Chem. Sci. 17:359), malignant human lymphocyte antigen-APO-1 (Bernhard et al., 1989, Science 245: 301-304), differentiation antigen (Feizi, 1985, Nature 314: 53-57) such as I antigen found in fetal erythrocytes, primary endoderm I antigen found in adult erythrocytes, preimplantation embryos, I(Ma) found in gastric adenocarcinomas, M18, M39 found in breast epithelium, SSEA-1 found in myeloid cells, VEP8, VEP9, Myl, VIM-D5, D₁56-22 found in colorectal cancer, TRA-1-85 (blood group H), C14 found in colonic adenocarcinoma, F3 found in lung adenocarcinoma, AH6 found in gastric cancer, Y hapten, Le^y found in embryonal carcinoma cells, TL5 (blood group A), EGF receptor found in A431 cells, E₁ series (blood group B) found in pancreatic cancer, FC10.2 found in embryonal carcinoma cells, gastric adenocarcinoma antigen, CO-514 (blood group Le^a) found in Adenocarcinoma, NS-10 found in adenocarcinomas, CO-43 (blood group Le^b), G49 found in EGF receptor of A431 cells, MH2 (blood group ALe^b/Le^y) found in colonic adenocarcinoma, 19.9 found in colon cancer, gastric cancer mucins, T₅A₇ found in myeloid cells, R₂₄ found in melanoma, 4.2, GD3, D1.1, OFA-1, G_M2, OFA-2, GD2, and M1:22:25:8 found in embryonal carcinoma cells, and SSEA-3 and SSEA-4 found in 4 to 8-cell stage embryos. In one embodiment, the antigen is a T cell receptor derived peptide from a Cutaneous Tcell Lymphoma (see, Edelson, 1998, The Cancer Journal 4:62).

[0321] In some embodiments, a variant Fc region of the invention is introduced into an anti-fluoresceine monoclonal antibody, 4-4-20 (Kranz et al., 1982 J. Biol. Chem. 257(12): 6987-6995; which is incorporated herein by reference in its entirety). In other embodiments, a variant Fc region of the invention is introduced into a mouse-human chimeric anti-CD20 monoclonal antibody 2H7, which recognizes the CD20 cell surface phosphoprotein on B cells (Liu et al., 1987, Journal of Immunology, 139: 3521-6; which is incorporated herein by reference in its entirety). In yet other embodiments, a variant Fc region of the invention is introduced into a humanized antibody (Ab4D5) against the human epidermal growth factor receptor 2 (p185 HER2) as described by Carter et al. (1992, Proc. Natl. Acad. Sci. USA 89: 4285-9; which is incorporated herein by reference in its entirety). In yet other embodiments, a variant Fc region of the invention is introduced into a humanized anti-TAG72 antibody (CC49) (Sha et al., 1994 Cancer Biother. 9(4): 341-9). In other embodiments, a variant Fc region of the invention is introduced into Rituxan which is used for treating lymphomas.

[0322] In another specific embodiment, the invention encompasses engineering an anti-FcγRIIB antibody including but not limited to any of the antibodies disclosed in U.S. Provisional Application No. 60/403,266 filed on Aug. 12, 2002, U.S. application Ser. No. 10/643,857 filed on Aug. 14, 2003, U.S. Provisional Application No. 60/562,804 filed on Apr. 16, 2004, U.S. Provisional Application No. 60/582,044 filed on Jun. 21, 2004, U.S. Provisional Application No. 60/582,045 filed on Jun. 21, 2004, U.S. Provisional Application No. 60/636,663 filed on Dec. 15, 2004 and U.S. application Ser. No. 10/524,134 filed Feb. 11, 2005 by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fc region for FcγRIIIA and/or FcγRIIA. In another specific embodiment, the invention encompasses engineering a humanized anti-FcγRIIB antibody including but not limited to any of the antibodies disclosed in U.S. Provisional Application No. 60/569,882 filed on May 10, 2004, U.S. Provisional Application No. 60/582,043 filed on Jun. 21, 2004 and U.S. application Ser. No. 11/126,978, filed on May 10, 2005 by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fc region for FcγRIIIA and/or FcγRIIA. Each of the above mentioned applications is incorporated herein by reference in its entirety. Examples of anti-FcγRIIB antibodies, which may or may not be humanized, that may be engineered in accordance with the methods of the invention are 2B6 monoclonal antibody having ATCC accession number PTA-4591 and 3H7 having ATCC accession number PTA-4592, 1D5 monoclonal antibody having ATCC accession number PTA-5958, 1F2 monoclonal antibody having ATCC accession number PTA-5959, 2D11 monoclonal antibody having ATCC accession number PTA-5960, 2E1 monoclonal antibody having ATCC accession number PTA-5961 and 2H9 monoclonal antibody having ATCC accession number PTA-5962 (all deposited at 10801 University Boulevard, Manassas, Va. 02209-2011), which are incorporated herein by reference. In another specific embodiment, modification of the anti-FcγRIIB antibody may also further decrease the affinity of the Fc region for FcγRIIB. In yet another specific embodiment, the engineered anti-FcγRIIB antibody may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein. In some embodiments, a variant Fc region of the invention is introduced into a therapeutic monoclonal antibody specific for a cancer antigen or cell surface receptor including but not limited to, Erbitux™ (also known as IMC-C225) (ImClone Systems Inc.), a chimerized monoclonal antibody against EGFR; HERCEPTIN® (Trastuzumab) (Genentech, CA) which is a humanized anti-HER2 monoclonal antibody for the treatment of patients with metastatic breast cancer; REOPRO® (abciximab) (Centocor) which is an anti-glycoprotein IIb/IIIa receptor on the platelets for the prevention of clot formation; ZENAPAX® (daclizumab) (Roche Pharmaceuticals, Switzerland) which is an immunosuppressive, humanized anti-CD25 monoclonal antibody for the prevention of acute renal allograft rejection. Other examples are a humanized anti-CD18 F(ab′)₂ (Genentech); CDP860 which is a humanized anti-CD18 F(ab′)₂ (Celltech, UK); PRO542 which is an anti-HIV gp120 antibody fused with CD4 (Progenics/Genzyme Transgenics); C14 which is an anti-CD14 antibody (ICOS Pharm); a humanized anti-VEGF IgG1 antibody (Genentech); OVAREX™ which is a murine anti-CA 125 antibody (Altarex); PANOREX™ which is a murine anti-17-IA cell surface antigen IgG2a antibody (Glaxo Wellcome/Centocor); IMC-C225 which is a chimeric anti-EGFR IgG antibody (ImClone System); VITAXIN™ which is a humanized anti-αVβ3 integrin antibody (Applied Molecular Evolution/MedImmune); Campath 1H/LDP-03 which is a humanized anti CD52 IgG1 antibody (Leukosite); Smart M195 which is a humanized anti-CD33 IgG antibody (Protein Design Lab/Kanebo); RITUXAN™ which is a chimeric anti-CD20 IgG1 antibody (IDEC Pharm/Genentech, Roche/Zettyaku); LYMPHOCIDE™ which is a humanized anti-CD22 IgG antibody (Immunomedics); Smart ID10 which is a humanized anti-HLA antibody (Protein Design Lab); ONCOLYM™ (Lym-1) is a radiolabelled murine anti-HLA DR antibody (Techniclone); anti-CD11a is a humanized IgG1 antibody (Genetech/Xoma); ICM3 is a humanized anti-ICAM3 antibody (ICOS Pharm); IDEC-114 is a primatized anti-CD80 antibody (IDEC Pharm/Mitsubishi); ZEVALIN™ is a radiolabelled murine anti-CD20 antibody (IDEC/Schering AG); IDEC-131 is a humanized anti-CD40L antibody (IDEC/Eisai); IDEC-151 is a primatized anti-CD4 antibody (IDEC); IDEC-152 is a primatized anti-CD23 antibody (IDEC/Seikagaku); SMART anti-CD3 is a humanized anti-CD3 IgG (Protein Design Lab); 5G1.1 is a humanized anti-complement factor 5 (C5) antibody (Alexion Pharm); IDEC-151 is a primatized anti-CD4 IgG1 antibody (IDEC Pharm/SmithKline Beecham); MDX-CD4 is a human anti-CD4 IgG antibody (Medarex/Eisai/Genmab); CDP571 is a humanized anti-TNF-α IgG4 antibody (Celltech); LDP-02 is a humanized anti-α4β7 antibody (LeukoSite/Genentech); OrthoClone OKT4A is a humanized anti-CD4 IgG antibody (Ortho Biotech); ANTOVA™ is a humanized anti-CD40L IgG antibody (Biogen); ANTEGREN™ is a humanized anti-VLA-4 IgG antibody (Elan); MDX-33 is a human anti-CD64 (FcγR) antibody (Medarex/Centeon); rhuMab-E25 is a humanized anti-IgE IgG1 antibody (Genentech/Norvartis/Tanox Biosystems); IDEC-152 is a primatized anti-CD23 antibody (IDEC Pharm); ABX-CBL is a murine anti CD-147 IgM antibody (Abgenix); BTI-322 is a rat anti-CD2 IgG antibody (Medimmune/Bio Transplant); Orthoclone/OKT3 is a murine anti-CD3 IgG2a antibody (ortho Biotech); SIMULEC™ is a chimeric anti-CD25 IgG1 antibody (Novartis Pharm); LDP-01 is a humanized anti-β2-integrin IgG antibody (LeukoSite); Anti-LFA-1 is a murine anti CD18 F(ab′)₂ (Pasteur-Merieux/Immunotech); CAT-152 is a human anti-TGF-β₂ antibody (Cambridge Ab Tech); and Corsevin M is a chimeric anti-Factor VII antibody (Centocor).

[0323] The variant Fc regions of the invention, preferably in the context of an immunoglobulin, can be further characterized using one or more biochemical assays and/or one or more functional assays, preferably in a high throughput manner. In some alternate embodiments, the variant Fc regions of the inventions are not introduced into an immunoglobulin and are further characterized using one or more biochemical based assays and/or one or more functional assays, preferably in a high throughput manner. The one or more biochemical assays can be any assay known in the art for identifying Fc-FcγR interactions, including, but not limited to, an ELISA assay, and surface plasmon resonance-based assay for determining the kinetic parameters of Fc-FcγR interaction, e.g., BIAcore assay. The one or more functional assays can be any assay known in the art for characterizing one or more FcγR mediated effector cell function as known to one skilled in the art or described herein. In specific embodiments, the immunoglobulins comprising the variant Fc regions are assayed in an ELISA assay for binding to one or more FcγRs, e.g., FcγRIIIA, FcγRIIA, FcγRIIA; followed by one or more ADCC assays. In some embodiments, the immunoglobulins comprising the variant Fc regions are assayed further using a surface plasmon resonance-based assay, e.g., BIAcore. Surface plasmon resonance-based assays are well known in the art, and are further discussed in Section 5.2.7, and exemplified herein in Example 6.8.

[0324] An exemplary high throughput assay for characterizing immunoglobulins comprising variant Fc regions may comprise: introducing a variant Fc region of the invention, e.g., by standard recombinant DNA technology methods, in a 4-4-20 antibody; characterizing the specific binding of the 4-4-20 antibody comprising the variant Fc region to an FcγR (e.g., FcγRIIIA, FcγRIIB) in an ELISA assay; characterizing the 4-4-20 antibody comprising the variant Fc region in an ADCC assay (using methods disclosed herein) wherein the target cells are opsonized with the 4-4-20 antibody comprising the variant Fc region; the variant Fc region may then be cloned into a second immunoglobulin, e.g., 4D5, 2H7, and that second immunoglobulin characterized in an ADCC assay, wherein the target cells are opsonized with the second antibody comprising the variant Fc region. The second antibody comprising the variant Fc region is then further analyzed using an ELISA-based assay to confirm the specific binding to an FcγR.

[0325] Preferably, a variant Fc region of the invention binds FcγRIIIA and/or FcγRIIA with a higher affinity than a wild type Fc region as determined in an ELISA assay. Most preferably, a variant Fc region of the invention binds FcγRIIIA and/or FcγRIIA with a higher affinity and binds FcγRIIB with a lower affinity than a wild type Fc region as determined in an ELISA assay. In some embodiments, the variant Fc region binds FcγRIIIA and/or FcγRIIA with at least 2-fold higher, at least 4-fold higher, more preferably at least 6-fold higher, most preferably at least 8 to 10-fold higher affinity than a wild type Fc region binds FcγRIIIA and/or FcγRIIA and binds FcγRIIB with at least 2-fold lower, at least 4-fold lower, more preferably at least 6-fold lower, most preferably at least 8 to 10-fold lower affinity than a wild type Fc region binds FcγRIIB as determined in an ELISA assay.

[0326] The immunoglobulin comprising the variant Fc regions may be analyzed at any point using a surface plasmon based resonance based assay, e.g., BIAcore, for defining the kinetic parameters of the Fc-FcγR interaction, using methods disclosed herein and known to those of skill in the art. Preferably, the Kd of a variant Fc region of the invention for binding to a monomeric FcγRIIIA and/or FcγRIIA as determined by BIAcore analysis is about 100 nM, preferably about 70 nM, most preferably about 40 nM; and the Kd of the variant Fc region of the invention for binding a dimeric FcγRIIB is about 80 nM, about 100 nM, more preferably about 200 nM.

[0327] In most preferred embodiments, the immunoglobulin comprising the variant Fc regions is further characterized in an animal model for interaction with an FcγR. Preferred animal models for use in the methods of the invention are, for example, transgenic mice expressing human FcγRs, e.g., any mouse model described in U.S. Pat. Nos. 5,877,397, and 6,676,927 which are incorporated herein by reference in their entirety. Transgenic mice for use in the methods of the invention include, but are not limited to, nude knockout FcγRIIIA mice carrying human FcγRIIIA; nude knockout FcγRIIIA mice carrying human FcγRIIA; nude knockout FcγRIIIA mice carrying human FcγRIIB and human FcγRIIIA; nude knockout FcγRIIIA mice carrying human FcγRIIB and human FcγRIIA; nude knockout FcγRIIIA and FcγRIIA mice carrying human FcγRIIIA and FcγRIIA and nude knockout FcγRIIIA, FcγRIIA and FcγRIIB mice carrying human FcγRIIIA, FcγRIIA and FcγRIIB.

[0328] 5.2.1 Design Strategies

[0329] The present invention encompasses engineering methods to generate Fc variants including but not limited to computational design strategies, library generation methods, and experimental production and screening methods. These strategies may be applied individually or in various combinations to engineer the Fc variants of the instant invention.

[0330] In most preferred embodiments, the engineering methods of the invention comprise methods in which amino acids at the interface between an Fc region and the Fc ligand are not modified. Fc ligands include but are not limited to FcγRs, C1q, FcRn, C3, mannose receptor, protein A, protein G, mannose receptor, and undiscovered molecules that bind Fc. Amino acids at the interface between an Fc region and an Fc ligand is defined as those amino acids that make a direct and/or indirect contact between the Fc region and the ligand, play a structural role in determining the conformation of the interface, or are within at least 3 angstroms, preferably at least 2 angstroms of each other as determined by structural analysis, such as x-ray crystallography and molecular modeling The amino acids at the interface between an Fc region and an Fc ligand include those amino acids that make a direct contact with an FcγR based on crystallographic and structural analysis of Fc-FcγR interactions such as those disclosed by Sondermann et al., (2000, Nature, 406: 267-273; which is incorporated herein by reference in its entirety). Examples of positions within the Fc region that make a direct contact with FcγR are amino acids 234-239 (hinge region), amino acids 265-269 (B/C loop), amino acids 297-299 (C′/E loop), and amino acids 327-332 (F/G) loop. In some embodiments, the molecules of the invention comprising variant Fc regions comprise modification of at least one residue that does not make a direct contact with an FcγR based on structural and crystallographic analysis, e.g., is not within the Fc-FcγR binding site.

[0331] Preferably, the engineering methods of the invention do not modify any of the amino acids as identified by Shields et al., which are located in the CH2 domain of an Fc region proximal to the hinge region, e.g., Leu234-Pro238; Ala327, Pro329, and affect binding of an Fc region to all human FcγRs.

[0332] In other embodiments, the invention encompasses Fc variants with altered FcγR affinities and/or altered effector functions, such that the Fc variant does not have an amino acid modification at a position at the interface between an Fc region and the Fc ligand. Preferably, such Fc variants in combination with one or more other amino acid modifications which are at the interface between an Fc region and the Fc ligand have a further impact on the particular altered property, e.g. altered FcγR affinity. Modifying amino acids at the interface between Fc and an Fc ligand may be done using methods known in the art, for example based on structural analysis of Fc-ligand complexes. For example but not by way of limitation by exploring energetically favorable substitutions at Fc positions that impact the binding interface, variants can be engineered that sample new interface conformations, some of which may improve binding to the Fc ligand, some of which may reduce Fc ligand binding, and some of which may have other favorable properties. Such new interface conformations could be the result of, for example, direct interaction with Fc ligand residues that form the interface, or indirect effects caused by the amino acid modifications such as perturbation of side chain or backbone conformations

[0333] The invention encompasses engineering Fc variants comprising any of the amino acid modifications disclosed herein in combination with other modifications in which the conformation of the Fc carbohydrate at position 297 is altered. The invention encompasses conformational and compositional changes in the N297 carbohydrate that result in a desired property, for example increased or reduced affinity for an FcγR. Such modifications may further enhance the phenotype of the original amino acid modification of the Fc variants of the invention. Although not intending to be bound by a particular mechanism of actions such a strategy is supported by the observation that the carbohydrate structure and conformation dramatically affect Fc-FcγR and Fc/C1q binding (Umaha et al., 1999, Nat Biotechnol 17:176-180; Davies et al., 2001, Biotechnol Bioeng 74:288-294; Mimura et al., 2001, J Biol Chem 276:45539; Radaev et al., 2001, J Biol Chem 276:16478-16483; Shields et al. 2002, J Biol Chem 277:26733-26740; Shinkawa et al., 2003, J Biol Chem 278:3466-3473).

[0334] Another design strategy for generating Fc variants in accordance with the invention is provided in which the Fc region is reengineered to eliminate the structural and functional dependence on glycosylation. This design strategy involves the optimization of Fc structure, stability, solubility, and/or Fc function (for example affinity of Fc for one or more Fc ligands) in the absence of the N297 carbohydrate. In one approach, positions that are exposed to solvent in the absence of glycosylation are engineered such that they are stable, structurally consistent with Fc structure, and have no tendency to aggregate. Approaches for optimizing aglycosylated Fc may involve but are not limited to designing amino acid modifications that enhance aglycoslated Fc stability and/or solubility by incorporating polar and/or charged residues that face inward towards the Cg2-Cg2 dimer axis, and by designing amino acid modifications that directly enhance the aglycosylated Fc-FcγR interface or the interface of aglycosylated Fc with some other Fc ligand.

[0335] The Fc variants of the present invention may be combined with other Fc modifications, including but not limited to modifications that alter effector function. The invention encompasses combining an Fc variant of the invention with other Fc modifications to provide additive, synergistic, or novel properties in antibodies or Fc fusions. Such modifications may be in the CH1, CH2, or CH3 domains or a combination thereof. Preferably the Fc variants of the invention enhance the property of the modification with which they are combined. For example, if an Fc variant of the invention is combined with a mutant known to bind FcγRIIIA with a higher affinity than a comparable molecule comprising a wild type Fc region; the combination with a mutant of the invention results in a greater fold enhancement in FcγRIIIA affinity.

[0336] In one embodiment, the Fc variants of the present invention may be combined with other known Fc variants such as those disclosed in Duncan et al, 1988, Nature 332:563-564; Lund et al., 1991, J. Immunol 147:2657-2662; Lund et al, 1992, Mol Immunol 29:53-59; Alegre et al, 1994, Transplantation 57:1537-1543; Hutchins et al., 1995, Proc Natl. Acad Sci USA 92:11980-11984; Jefferis et al, 1995, Immunol Lett. 44:111-117; Lund et al., 1995, Faseb J 9:115-119; Jefferis et al, 1996, Immunol Lett 54:101-104; Lund et al, 1996, J Immunol 157:49634969; Armour et al., 1999, Eur J Immunol 29:2613-2624; Idusogie et al, 2000, J Immunol 164:41784184; Reddy et al, 2000, J Immunol 164:1925-1933; Xu et al., 2000, Cell Immunol 200:16-26; Idusogie et al, 2001, J Immunol 166:2571-2575; Shields et al., 2001, J Biol Chem 276:6591-6604; Jefferis et al, 2002, Immunol Lett 82:57-65; Presta et al., 2002, Biochem Soc Trans 30:487-490); U.S. Pat. No. 5,624,821; U.S. Pat. No. 5,885,573; U.S. Pat. No. 6,194,551; PCT WO 00/42072; PCT WO 99/58572; each of which is incorporated herein by reference in its entirety.

[0337] 5.2.2 FcγR-Fc Binding Assay

[0338] An FcγR-Fc binding assay was developed for determining the binding of the molecules of the invention comprising variant Fc regions to FcγR, which allowed detection and quantitation of the interaction, despite the inherently weak affinity of the receptor for its ligand, e.g., in the micromolar range for FcγRIIB and FcγRIIIA. The method involves the formation of an FcγR complex that has an improved avidity for an Fc region, relative to an uncomplexed FcγR. According to the invention, the preferred molecular complex is a tetrameric immune complex, comprising: (a) the soluble region of FcγR (e.g., the soluble region of FcγRIIIA, FcγRIIA or FcγRIIB); (b) a biotinylated 15 amino acid AVITAG sequence (AVITAG) operably linked to the C-terminus of the soluble region of FcγR (e.g., the soluble region of FcγRIIIA, FcγRIIA or FcγRIIB); and (c) streptavidin-phycoerythrin (SA-PE); in a molar ratio to form a tetrameric FcγR complex (preferably in a 5:1 molar ratio). According to a preferred embodiment of the invention, the fusion protein is biotinylated enzymatically, using for example, the E. coli Bir A enzyme, a biotin ligase which specifically biotinylates a lysine residue in the 15 amino acid AVITAG sequence. In a specific embodiment of the invention, 85% of the fusion protein is biotinylated, as determined by standard methods known to those skilled in the art, including but not limited to streptavidin shift assay. According to preferred embodiments of the invention, the biotinylated soluble FcγR proteins are mixed with SA-PE in a 1×SA-PE:5× biotinylated soluble FcγR molar ratio to form a tetrameric FcγR complex.

[0339] In a preferred embodiment of the invention, polypeptides comprising Fc regions bind the tetrameric FcγR complexes, formed according to the methods of the invention, with at least an 8-fold higher affinity than the monomeric uncomplexed FcγR. The binding of polypeptides comprising Fc regions to the tetrameric FcγR complexes may be determined using standard techniques known to those skilled in the art, such as for example, fluorescence activated cell sorting (FACS), radioimmunoassays, ELISA assays, etc.

[0340] The invention encompasses the use of the immune complexes formed according to the methods described above, for determining the functionality of molecules comprising an Fc region in cell-based or cell-free assays.

[0341] As a matter of convenience, the reagents may be provided in an assay kit, i.e., a packaged combination of reagents for assaying the ability of molecules comprising variant Fc regions to bind FcγR tetrameric complexes. Other forms of molecular complexes for use in determining Fc-FcγR interactions are also contemplated for use in the methods of the invention, e.g., fusion proteins formed as described in U.S. Provisional Application 60/439,709, filed on Jan. 13, 2003 (Attorney Docket No. 11183-005-888); which is incorporated herein by reference in its entirety.

[0342] 5.2.3 Mutagenesis and Construction of Yeast Display Libraries

[0343] Molecular interactions between the IgG Fc and Fc receptors have been previously studied by both structural and genetic techniques. These studies identified amino acid residues that are critical for functional binding of Fc to different FcγR. None of these changes have been shown to improve human FcγR mediated efficacy of therapeutic antibodies in animal models. A complete analysis of all potential amino acid changes at these residues or other potentially important residues has not been reported. The platform described herein has the ability to both construct mutant libraries with all possible amino acid changes, screen libraries using multiple functional assays, and finally analyze libraries in relevant humanized animal models.

[0344] The instant invention encompasses construction of multiple libraries based on both genetic and structural data known in the art or being developed. The method described and exemplified herein incorporates building individual libraries that contain mutants testing all 20 amino acid changes at between 3-6 residues in the Fc region. The complete set of mutations will be assembled in all possible combinations of mutations. The number of independent mutations generated is based on the number of sites being saturated during library assembly (Table 9 below). Library size will determine the choice of primary screen and therefore the choice of vector for initial cloning steps.

TABLE 9
Number of Independent mutants based on number of targeted sites.
Library	# of residues	# independent mutants	Primary screen
Small	3 or less	8000 max.	ELISA
Large	4-6	1.6 × 105-6.4 × 107	Surface display

[0345] The instant invention encompasses construction of combinatorial libraries, focusing on a limited number of critical residues (e.g., 3-6). Using a library of randomly mutagenized IgG1 Fc and the screening assays described and exemplified herein Fc variants will be identified. In the initial rounds, the best 5 mutations, based on both FcR binding profile and functional activity will be selected. It will take 20⁵ individual mutants to cover all possible amino acid changes and their combinations at five locations. A library with at least 10-fold coverage for each mutant will be generated. In addition regions will be chosen based on available information, e.g., crystal structure data, Mouse/Human isotype FcγR binding differences, genetic data, and additional sites identified by mutagenesis.

[0346] The biggest disadvantage of current site directed mutagenic protocols is production of bias populations, over-representing variations in some regions and under-representing or completely lacking mutations in others. The present invention overcomes this problem by generating unbiased arrays of desirable Fc mutants using a well-developed gene building technology to eliminate the bias introduced in library construction by PCR based approaches such as overlapping PCR and inverted PCR. The key distinctions of the approach of the present invention are: 1) Employment of equimolar mix of 20 individual oligos for every targeted codon instead of degenerated primers. This way each amino acid is represented by a single, most used codon, whereas degenerated primers over represent those amino acids encoded by more codons over those encoded by fewer codons. 2) Building mutants by a chain replacement approach. This insures unbiased introduction of all desirable changes into the final product.

[0347] An exemplary protocol comprises of the following steps: 1) phosphorylated oligos, representing desirable changes at one or several locations, all complementary to the same strand, added to the template along with a thermostable, 5′>3′ exonuclease deficient, DNA polymerase and ligase (FIG. 27 a). 2) assembled mix undergoes a number of polymerization/ligation cycles, sufficient to generate desirable amount of product. Use of a 5′>3′ exonuclease deficient DNA polymerase insures integrity of the primer sequence and its phosphate residue, when a thermostable ligase assembles individual primer-extended fragments into a contiguous single-stranded chain. Reaction cycles can continue until complete exhaustion of the oligos pool without introducing bias into the final product (FIG. 27 b). 3) generated pool of single-stranded mutants is converted into double-stranded DNA by adding a reverse gene-specific primer to the reaction (FIG. 27 1c). 4) double-stranded product gets digested at the end-designed restriction sites and cloned into an appropriate expression vector (FIG. 27 1d)

[0348] To insure quality of the library, PCR amplified fragments will be analyzed by electrophoresis to determine the length of the final PCR products. The reaction will be characterized as successful if >99% of the PCR products are of the expected length. The final library will be cloned into an expression vector. A fraction of the mutant library will be sequenced to determine the rate of mutant codon incorporation. The number of fragments sequenced will be based on the number of target sites mutated and library validation will be determined by the observed rate of mutation at targeted sites (Table 10). The rate of vector without inserts should be less than 2%. The rate of mutation at non-targeted sites should be less than 8%. Libraries containing clones with >90% correct inserts will allow us to maintain screening timelines.

TABLE 10
Expected rates of Mutation for Libraries
	# of	Approx. rates of mutation
Targeted	seq. re-	for library validation
Residues	actions	Single	Double	Triple	Quad.	Pent.	Hex.
3	20	42%	43%	15%	NA	NA	NA
4	50	29%	43%	21%	7%	NA	NA
5	75	18%	35%	32%	11%	4%	NA
6	100	12%	20%	40%	20%	6%	2%

[0349] In other embodiments, the invention the invention encompasses overlapping or inverted PCR for construction of libraries. In order to remain unbiased, individual primers for each codon will be used rather than degenerative primers. A similar validation scheme as disclosed supra will be employed.

[0350] Most preferably automated protocols will be employed for high throughput library production. Automation allows for improved throughput, walk away operation, and an overall reduction in experimental error for tasks requiring tedious repetitive operations. Oligo synthesis capabilities is based on 2 Mermade DNA synthesizers (Bioautomation, Inc.) with a total output capability of 575 60mer Oligos/12 hrs. Proprietary software handles all aspects of design, synthesis, and storage of the final oligonucleotides. Robotic liquid handlers will be employed to set up oligos for synthesis of full length Fc mutants and ligation reactions for incorporating the mutant Fcs into antibody heavy chain expression vectors will be set up. After ligation it is estimated that it would take 1 FTE ˜10 days to array the library clones and generate ˜8000 minipreps, equivalent to a combinatorial library saturated at 3 sites. Subsequent to bacterial transformation a Qpix-2 clone picker robot will be used for picking colonies into 96 deep well plates. Culture growth will be done using a magnetic levitation stirrer, capable of incubating 12 plates and resulting in dense growth in 12-16 hr at 37° C. A Qiagen miniprep robot will be used to perform DNA preps at the rate of 4 96 well plates in 2.5 hrs. By overlapping tasks 5 such libraries could be constructed in 9 months with 1 FTE

[0351] Affinity maturation requires the assembly of a new set of combinations of mutations, from a preselected mutant pool or members of a gene family, which can be enriched by a selection protocol. The process is repeated several times until the isolation of a mutant with the desired phenotype is achieved. The disadvantage of the current enzymatic approach, DNA shuffling, to accomplish this process is bias which can be introduced due to specific sites within gene that are hot spots for nucleases, dominance of specific mutants in the final reassembled pool and loss of some of the original mutants in the final pool. In order to overcome this shortcoming a build-a-gene (BAG) technology will be used to generate a highly complex library of Fc mutants containing random amino acid changes at all potential locations that may be important for receptor(s) binding. Sets of degenerated oligos covering specific regions of the IgG Fc will be used (See FIG. 28).

[0352] Oligos will be ˜30 nt and and degenerate oligos synthesized to change one (4 oligos) or two AAs (8 oligos) will be constructed. The oligos are designed to be overlapping with no gaps. It will take ˜200 oligos to accommodate all single AA changes and ˜2000 to change two AAs per oligonucleotide. All 2000+ oligos will be used individually and in combinations to generate arrays of Fc mutants using the protocol outlined above (A.20). We will use a home-written randomizer program and a robotic liquid handler for pooling selected combinations of mutant and wild type oligos. Large libraries will be cloned into vectors that will allow for screening using yeast surface display. This approach utilizes a magnetic bead selection followed by flow cytometry and has been successfully applied to libraries with a complexity >10⁹ (Feldhaus et al., 2003, Nat. Biotech. 21(2): 163-170; which is incorporated herein by reference in its entirety). This limits the number of sites to test at any one pool to 7, resulting in ˜1.3×10⁹ possible mutations/pool.

[0353] To insure quality of the library PCR amplified fragments will be analyzed by electrophoresis to determine the length of the final PCR products. The reaction will be characterized as successful if >99% of the PCR products are of the expected length. A fraction of the mutant library will be sequenced to determine the rate of mutant codon incorporation. The number of fragments sequenced will be based on the number of target sites mutated and library validation will be determined by the observed rate of mutation at targeted sites (Table 10). The rate of vectors without inserts should be less than 2%. The rate of mutation at non-targeted sites should be less than 8%.

[0354] The ability to generate the desired level of efficiency of mutagenesis by this approach will be determined by sequencing of a subset of clones. The alternative to BAG will be using a “DNA shuffle” protocol. This requires pooling all of the mutants, single, double, triple, etc. Following DNA preparation, Fc regions will be amplified by PCR using flanking primers that selectively amplify the mutated region of the Fc, 700 bp. Novel mutants are constructed by reshuffling of mutations in the Fc via DNAseI treatment of the amplified DNA and isolation of 150-200 bp fragments (see, e.g., Stemmer et al., 1994, Proc. Natl. Acad. Sci. U.S.A. 91: 10747-51). Fragments will be religated, PCR amplified with nested primers and cloned into the yeast surface display vector, pYD1. The recombined library will be reselected in the yeast Fc display screen as described and exemplified herein.

[0355] BAG libraries will utilize most of the same equipment as the combinatorial library. However cloning will be in a vector suitable for yeast surface display and will not require arraying of individual clones as the yeast surface display will initially be employed for enrichment of large libraries. Subsequent to the appropriate level of enrichment individual clones will be arrayed.

[0356] An initial library of molecules comprising variant Fc regions is produced using any random based mutagenesis techniques known in the art. It will be appreciated by one of skill in the art that amino acid sequence variants of Fc regions may be obtained by any mutagenesis technique known to those skilled in the art. Some of these techniques are briefly described herein, however, it will be recognized that alternative procedures may produce an equivalent result. In a preferred embodiment molecules of the invention comprising variant Fc regions are prepared by error-prone PCR as exemplified in Example 6, infra (See Leung et al., 1989, Technique, 1:11). It is especially preferred to have error rates of 2-3 bp/Kb for use in the methods of the invention. In one embodiment, using error prone PCR a mutation frequency of 2-3 mutations/kb is obtained.

[0357] Mutagenesis may be performed in accordance with any of the techniques known in the art including, but not limited to, synthesizing an oligonucleotide having one or more modifications within the sequence of the Fc region of an antibody or a polypeptide comprising an Fc region (e.g., the CH2 or CH3 domain) to be modified. Site-specific mutagenesis allows the production of mutants through the use of specific oligonucleotide sequences which encode the DNA sequence of the desired mutation, as well as a sufficient number of adjacent nucleotides, to provide a primer sequence of sufficient size and sequence complexity to form a stable duplex on both sides of the deletion junction being traversed. Typically, a primer of about 30 to about 45 nucleotides or more in length is preferred, with about 10 to about 25 or more residues on both sides of the junction of the sequence being altered. A number of such primers introducing a variety of different mutations at one or more positions may be used to generated a library of mutants.

[0358] The technique of site-specific mutagenesis is well known in the art, as exemplified by various publications (see, e.g., Kunkel et al., Methods Enzymol., 154:367-82, 1987, which is hereby incorporated by reference in its entirety). In general, site-directed mutagenesis is performed by first obtaining a single-stranded vector or melting apart of two strands of a double stranded vector which includes within its sequence a DNA sequence which encodes the desired peptide. An oligonucleotide primer bearing the desired mutated sequence is prepared, generally synthetically. This primer is then annealed with the single-stranded vector, and subjected to DNA polymerizing enzymes such as T7 DNA polymerase, in order to complete the synthesis of the mutation-bearing strand. Thus, a heteroduplex is formed wherein one strand encodes the original non-mutated sequence and the second strand bears the desired mutation. This heteroduplex vector is then used to transform or transfect appropriate cells, such as E. coli cells, and clones are selected which include recombinant vectors bearing the mutated sequence arrangement. As will be appreciated, the technique typically employs a phage vector which exists in both a single stranded and double stranded form. Typical vectors useful in site-directed mutagenesis include vectors such as the M13 phage. These phage are readily commercially available and their use is generally well known to those skilled in the art. Double stranded plasmids are also routinely employed in site directed mutagenesis which eliminates the step of transferring the gene of interest from a plasmid to a phage.

[0359] Alternatively, the use of PCR™ with commercially available thermostable enzymes such as Taq DNA polymerase may be used to incorporate a mutagenic oligonucleotide primer into an amplified DNA fragment that can then be cloned into an appropriate cloning or expression vector. See, e.g., Tomic et al., Nucleic Acids Res., 18(6):1656, 1987, and Upender et al., Biotechniques, 18(1):29-30, 32, 1995, for PCR™-mediated mutagenesis procedures, which are hereby incorporated in their entireties. PCR™ employing a thermostable ligase in addition to a thermostable polymerase may also be used to incorporate a phosphorylated mutagenic oligonucleotide into an amplified DNA fragment that may then be cloned into an appropriate cloning or expression vector (see e.g., Michael, Biotechniques, 16(3):410-2, 1994, which is hereby incorporated by reference in its entirety)

[0360] Another method for preparing variants for use in the invention, is cassette mutagenesis based on the technique described by Wells et al. (1985, Gene, 34: 315). The starting material is the plasmid comprising the desired DNA encoding the protein to be mutated (e.g., the DNA encoding a polypeptide comprising an Fc region). The codon(s) in the DNA sequence to be mutated are identified; there must be a unique restriction endonuclease site on each side of the identified mutations site(s). If no such restriction site exits, it may be generated by oligonucleotide directed mutagenesis. After the restriction sites have been introduced into the plasmid, the plasmid is cut at these sites and linearized. A double-stranded oligonucleotide encoding the sequence of the DNA between the restriction sites but containing the mutation is synthesized using standard procedures known to those skilled in the art. The double stranded oligonucleotide is referred to as the cassette. This cassette is designed to have 3′ and 5′ ends that are compatible with the ends of the linearized plasmid, such that it can be directly ligated to the plasmid.

[0361] Other methods known to those of skill in the art for producing sequence variants of the Fc region of an antibody or polypeptides comprising an Fc region can be used. For example, recombinant vectors encoding the amino acid sequence of the constant domain of an antibody or a fragment thereof may be treated with mutagenic agents, such as hydroxylamine, to obtain sequence variants.

[0362] Once a mutant library is produced according to the methods described, the mutagenized library is transformed into a yeast strain, preferably EBY100 (Invitrogen), MATa ura3-52 trpl leu2Δl his3Δ200 pep4::HIS3prb1Δ1.6R can1 GAL::GAL-AGA1 using a standard lithium acetate transformation protocol known to those skilled in the art (ref).

[0363] It will be appreciated by one of skill in the art, that once molecules of the invention with desired binding properties (e.g., molecules with variant Fc regions with at least one amino acid modification, which modification enhances the affinity of the variant Fc region for FcγRIIIA relative to a comparable molecule, comprising a wild-type Fc region) have been identified (See Section 5.1 and Table 2) according to the methods of the invention, other molecules (i.e., therapeutic antibodies) may be engineered using standard recombinant DNA techniques and any known mutagenesis techniques, as described in this section to produce engineered molecules carrying the identified mutation sites.

[0364] 5.2.4 Yeast Surface Display

[0365] The preferred method for screening and identifying molecules comprising variant Fc regions with altered FcγR affinities (i.e., enhanced FcγRIIIA affinity and/or FcγRIIA) is yeast surface display technology (for review see Boder and Wittrup, 2000, Methods in Enzymology, 328: 430-444, which is incorporated herein by reference in its entirety) which addresses the deficiency in the prior art for screening binding interactions of extracellular post-translationally modified proteins. Specifically, the yeast surface display is a genetic method whereby polypeptides comprising Fc mutants are expressed on the yeast cell wall in a form accessible for interacting with FcγR. Yeast surface display of the mutant Fc containing polypeptides of the invention may be performed in accordance with any of the techniques known to those skilled in the art. See U.S. Pat. Nos. 6,423,538; 6,114,147; and 6,300,065, all of which are incorporated herein by reference in their entirety. See Boder et al., 1997 Nat. Biotechnol., 15:553-7; Boder et al., 1998 Biotechnol. Prog., 14:55-62; Boder et al., 2000 Methods Enzymol., 328:430-44; Boder et al., 2000 Proc. Natl. Acad. Sci. U.S., 2000, 97:10701-5; Shusta et al., 1998 Nat. Biotechnol., 1998, 16:773-7; Shusta et al., 1999 J. Mol. Biol., 292:949-56; Shusta et al., 1999 Curr. Opin. Biotechnol., 10:117-22; Shusta et al., 2000 Nat. Biotechnol., 18:754-9; Wittrup et al., 1994 Ann. N.Y. Acad. Sci., 745:321-30; Wittrup et al., 1994 Cytometry, 16:206-13; Wittrup, 1995 Curr. Opin. Biotechnol., 6:203-8; Wittrup, 1999 Trends Biotechnol., 17:423-4; Wittrup, 2000 Nat. Biotechnol., 18:1039-40; Wittrup, 2001 Curr. Opin. Biotechnol., 12:395-9.

[0366] Yeast Surface Display will be used to enrich libraries containing >10⁷ independent clones. This approach will provide the ability to enrich large libraries >20-fold in single sort. Fc mutant libraries with >10,000 independent mutants (4 or more sites) will be cloned into the appropriate vectors for yeast surface display and enriched by FACS sorting until <8000 mutants are able to be tested by other biochemical and functional assays as described below.

[0367] The invention provides methods for constructing an Fc mutant library in yeast for displaying molecules comprising Fc regions, which have been mutated as described in Section 5.2.2. Preferably, the Fc mutant libraries for use in the methods of the invention contain at least 10⁷ cells, up to 10⁹ cells. One exemplary method for constructing a Fc library for use in the methods of the invention comprises the following: nucleic acids encoding molecules comprising Fc regions are cloned into the multiple cloning site of a vector derived from a yeast replicating vector, e.g., pCT302; such that the Fc encoding nucleic acids are expressed under the control of the GAL1 galactose-inducible promoter and in-frame with a nucleotide sequence encoding Aga2p, the mating agglutinin cell wall protein. In a preferred embodiment, nucleic acids encoding molecules comprising Fc regions are cloned C-terminal to the Aga2p coding region, such that a Fc-region Aga2p fusion protein is encoded. A fusion protein comprising the Aga2p protein and polypeptides comprising Fc regions will be secreted extracellularly and displayed on the cell wall via disulfide linkage to the Aga1p protein, an integral cell wall protein, using the preferred construct of the invention. In an alternative embodiment, the constructs may further comprise nucleotide sequences encoding epitope tags. Any epitope tag nucleotide coding sequence known to those skilled in the art can be used in accordance with the invention, including, but not limited to nucleotide sequences encoding hemagglutinin (HA), c-myc Xpress TAG, His-TAG, or V5TAG. The presence of the fusion protein on the yeast cell surface may be detected using FACS analysis, confocal fluorescence microscopy or standard immunostaining methods, all of which are known to those skilled in the art. In one embodiment, the presence of the Fc fusion proteins of the invention on the yeast cell surface are detected using Fc-specific monoclonal antibodies (CH3 specific), including but not limited to IgG1 Fc-specific monoclonal antibody, HP6017 (Sigma), JL512 (Immunotech), and any antibody disclosed in Partridge et al., 1986, Molecular Immunology, 23 (12): 1365-72, which is incorporated herein by reference in its entirety. In another embodiment, the presence of the Fc fusion proteins of the invention are detected by immunofluorescent labeling of epitope tags using techniques known to those skilled in the art. It is particularly useful in the methods of the invention, to use nucleotide sequences encoding epitope tags to flank the nucleic acids encoding the Fc fusion proteins, as an internal control, to detect if the fusion proteins are displayed on the cell wall in a partially proteolyzed form.

[0368] 5.2.5 Screening of Yeast Display Libraries

[0369] The invention encompasses screening the yeast display libraries using immunological based assays including but not limited to cell based assays, solution based assays, and solid phase based assays.

[0370] In some embodiments, the invention encompasses identification of Fc mutants with altered FcγR affinities using affinity maturation methods which are known to those skilled in the art and encompassed herein. Briefly, affinity maturation creates novel alleles by randomly recombining individual mutations present in a mutant library, see, e.g., Hawkins et al., 1992, J. Mol. Biol. 226: 889-896; Stemmer et al., 1994 Nature, 370: 389-91; both of which are incorporated herein by reference in their entireties. It has been used successfully to increase the affinity of antibodies, T cell receptors and other proteins. The invention encompasses using mutations that show increased FcγR binding as a baseline to construct new mutant libraries with enhanced phenotypes. Using the methods of the invention, a population of IgG1 Fc mutants enriched by yeast surface display for increased binding to an FcγR, e.g., FcγRIIIA, may be selected. Following DNA preparation, Fc regions can be amplified by PCR using flanking primers that selectively amplify the mutated region of the Fc, which is about ˜700 bp using methods known to one skilled in the art and exemplified or disclosed herein. Novel mutants can thus be constructed by reshuffling of mutations in the Fc region for example via DNAseI treatment of the amplified DNA and isolation of fragments using methods such as those disclosed by Stemmer et al., 1994 Proc. Natl. Acad. Sci. USA 91: 10747-51, which is incorporated herein by reference in its entirety. Fragments can then be religated, PCR amplified with nested primers and cloned into the yeast display vector, e.g., pYD1 using methods known to one skilled in the art. The recombined library can then be reselected in the yeast Fc display screen. As the K_D decreases, below 10 nM, conditions can be established to allow for further increases in affinity based on the reduction of the off rate of the FcγRIIIA ligand from the Fc receptor using methods known in the art such as those disclosed in Boder et al., 1998, Biotechnol. Prog. 14: 55-62, which is incorporated herein by reference in its entirety. The invention encompasses a kinetic screen of the yeast library. A kinetic screen may be established by labeling of the Fc displaying cells to saturation with a labeled ligand, e.g., a fluorescent ligand followed by incubation with an excess of non-labeled ligand for a predetermined period. After termination of the reaction by the addition of excess buffer (e.g., 1×PBS, 0.5 mg/ml BSA) cells will be analyzed by FACS and sort gates set for selection. After each round of enrichment individual mutants can be tested for fold increases in affinity and sequenced for diversity. The in vitro recombination process can be repeated. In some embodiments, the in vitro is repeated at least 3 times.

[0371] Selection of the Fc variants of the invention may be done using any FcγR including but not limited to polymorphic variants of FcγR. In some embodiments, selection of the Fc variants is done using a polymorphic variant of FcγRIIIA which contains a phenylalanine at position 158. In other embodiments, selection of the Fc variants is done using a polymorphic variant of FcγRIIIA which contains a valine at position 158. FcγRIIIA 158V displays a higher affinity for IgG1 than 158F and an increased ADCC activity (see, e.g., Koene et al., 1997, Blood, 90:1109-14; Wu et al., 1997, J. Clin. Invest. 100: 1059-70, both of which are incorporated herein by reference in their entireties); this residue in fact directly interacts with the lower hinge region of IgG1 as recently shown by IgG1-FcγRIIIA co-crystallization studies, see, e.g., Sonderman et al., 2000, Nature, 100: 1059-70, which is incorporated herein by reference in its entirety. Studies have shown that in some cases therapeutic antibodies have improved efficacy in FcγRIIIA-158V homozygous patients. For example, humanized anti-CD20 monoclonal antibody Rituximab was therapeutically more effective in FcγRIIIA 158V homozygous patients compared to FcγRIIIA 158F homozygous patients (See, e.g., Cartron et al., 2002 Blood, 99(3): 754-8). Although not intending to be bound by a particular mechanism of action, selection of Fc variants of the invention with FcγRIIIA 158F allotype may provide for variants that once engineered into therapeutic antibodies will be clinically more efficacious for FcγRIIIA 158F homozygous patients.

[0372] The invention encompasses screening yeast libraries based on FcγRIIB depletion and FcγRIIIA selection so that Fc mutants are selected that not only have an enhanced affinity for FcγRIIIIA but also have a reduced affinity for FcγRIIB. Yeast libraries may be enriched for clones that have a reduced affinity for FcγRIIB by sequential depletion methods, for example, by incubating the yeast library with magnetic beads coated with FcγRIIB. FcγRIIB depletion is preferrably carried out sequentially so that the library is enriched in clones that have a reduced affinity for FcγRIIB. In some embodiments, the FcγRIIB depletion step results in a population of cells so that only 30%, preferably only 10%, more preferably only 5%, most preferably less than 1% bind FcγRIIB. In some embodiments, FcγRIIB depletion is carried out in at least 3 cycles, at least 4 cycles, at least 6 cycles. The FcγRIIB depletion step is preferrably combined with an FcγRIIIIA selection step, for example using FACS sorting so that Fc variants with an enhanced affinity for FcγRIIIIA are selected.

[0373] 5.2.5.1 FACS Assays; Solid Phased Assays and Immunological Based Assays

[0374] The invention encompasses characterization of the mutant Fe fusion proteins that are displayed on the yeast surface cell wall, according to the methods described in Section 5.2.3. One aspect of the invention provides a method for selecting mutant Fc fusion proteins with a desirable binding property, specifically, the ability of the mutant Fc fusion protein to bind FcγRIIIA and/or FcγRIIA with a greater affinity than a comparable polypeptide comprising a wild-type Fc region binds FcγRIIIA and/or FcγRIIA. In another embodiment, the invention provides a method for selecting mutant Fc fusion proteins with a desirable binding property, specifically, the ability of the mutant Fc fusion protein to bind FcγRIIIA and/or FcγRIIA with a greater affinity than a comparable polypeptide comprising a wild-type Fc region binds FcγRIIIA and/or FcγRIIA, and further the ability of the mutant Fc fusion protein to bind FcγRIIB with a lower affinity than a comparable polypeptide comprising a wild-type Fc region binds FcγRIIB. It will be appreciated by one skilled in the art, that the methods of the invention can be used for identifying and screening any mutations in the Fc regions of molecules, with any desired binding characteristic.

[0375] Yeast cells displaying the mutant Fc fusion proteins can be screened and characterized by any biochemical or immunological based assays known to those skilled in the art for assessing binding interactions.

[0376] Preferably, fluorescence activated cell sorting (FACS), using any of the techniques known to those skilled in the art, is used for screening the mutant Fc fusion proteins displayed on the yeast cell surface for binding FcγRIIIA, preferably the FcγRIIIA tetrameric complex, or optionally FcγRIIB. Flow sorters are capable of rapidly examining a large number of individual cells that contain library inserts (e.g., 10-100 million cells per hour) (Shapiro et al., Practical Flow Cytometry, 1995). Additionally, specific parameters used for optimization including, but not limited to, ligand concentration (i.e., FcγRIIIA tetrameric complex), kinetic competition time, or FACS stringency may be varied in order to select for the cells which display Fc fusion proteins with specific binding properties, e.g., higher affinity for FcγRIIIA compared to a comparable polypeptide comprising a wild-type Fc region. Flow cytometers for sorting and examining biological cells are well known in the art. Known flow cytometers are described, for example, in U.S. Pat. Nos. 4,347,935; 5,464,581; 5,483,469; 5,602,039; 5,643,796; and 6,211,477; the entire contents of which are incorporated by reference herein. Other known flow cytometers are the FACS Vantage™ system manufactured by Becton Dickinson and Company, and the COPAS™ system manufactured by Union Biometrica.

[0377] According to a preferred embodiment of the invention, yeast cells are analyzed by fluorescence activated cell sorting (FACS). In most preferred embodiments, the FACS analysis of the yeast cells is done in an iterative manner, at least twice, at least three times, or at least 5 times. Between each round of selection cells are regrown and induced so the Fc regions are displayed on the maximum number of yeast cell surfaces. Although not intending to be bound by a particular mode of action, this iterative process helps enrich the population of the cells with a particular phenotype, e.g., high binding to FcγRIIIA.

[0378] In preferred embodiments, screening for Fc variants of the invention comprises a selection process that has multiple rounds of screening, e.g., at least two rounds of screening. In one embodiment, screening for Fc variants that have an enhanced affinity for FcγRIIIA may comprise the following steps: in the first round of screening, a library of yeast cells, e.g., a naïve library of 10⁷ cells is enriched by FACS, preferably in an iterative manner, using for example labeled tetrameric FcγRIIIA to select for Fc variants that have an enhanced affinity for FcγRIIIA; the variant Fc region that is selected with the desired phenotype, e.g., enhanced binding to FcγRIIIA, is then introduced into an antibody, e.g., a 4-4-20 antibody, and the engineered antibody is assayed using a secondary screen, e.g., ELISA for binding to an FcγR. In the second round of screening, a single mutation library may be generated based on the first screen so that the Fc region harbors the variant displaying the enhanced affinity for FcγRIIIA; and enriched by FACS using for example labeled monomeric FcγRIIIA in both the presence and absence of unlabeled receptor; and the variant Fc region is then introduced into an antibody, e.g., a 4-4-20 antibody, and the engineered antibody is assayed using a secondary screen, e.g., ELISA for binding to an FcγR. In some embodiments, the secondary screen may further comprise characterizing the antibodies comprising Fc variants in an ADCC or BIAcore based assay using methods disclosed herein

[0379] The invention encompasses FACS screening of the mutant yeast library under equilibrium or kinetic conditions. When the screening is performed under equilibrium conditions, an excess of the yeast library carrying Fc mutants is incubated with FcγRIIIA, preferably labeled FcγRIIIA at a concentration 5-10 fold below the Kd, for at least one hour to allow binding of Fc mutants to FcγRIIIA under equilibrium conditions. When the screening is performed under kinetic conditions, the mutant yeast library is incubated with labeled FcγRIIIA; the cells are then incubated with equimolar unlabeled FcγRIIIA for a pre-selected time, bound FcγRIIIA is then monitored.

[0380] One exemplary method of analyzing the yeast cells expressing mutant Fc fusion proteins with FACS is costaining the cells with FcγRIIIA-tetrameric complex which has been labeled with a fluorescent label such as, PE and an anti-Fc antibody, such as F(ab)₂ anti-Fc which has been fluorescently labeled. Fluorescence measurements of a yeast library produced according to the methods of the invention preferably involves comparisons with controls; for example, yeast cells that lack the insert encoding molecules comprising an Fc region (negative control). The flow sorter has the ability not only to measure fluorescence signals in cells at a rapid rate, but also to collect cells that have specified fluorescent properties. This feature may be employed in a preferred embodiment of the invention to enrich the initial library population for cells expressing Fc fusion proteins with specific binding characteristics, e.g., higher affinity for FcγRIIIA compared to a comparable polypeptide comprising a wild-type Fc region. In a preferred embodiment of the invention, yeast cells are analyzed by FACS and sort gates established to select for cells that show the highest affinity for FcγRIIIA relative to the amount of Fc expression on the yeast cell surface. According to a preferred embodiment, four consecutive sorts are established, wherein the gates for each successive sort is 5.5%, 1%, 0.2%, and 0.1%. It is preferred that the yeast display library formed according to the methods of the invention be over-sampled by at least 10-fold to improve the probability of isolating rare clones (e.g., analyze ˜10⁸ cells from a library of 10⁷ clones). Alternatively, 2-5 sorts are established to select for cells of the desired phenotype. Sort gates can be established empirically by one skilled in the art.

[0381] In other preferred embodiments, mutant Fc fusion proteins displayed on the yeast cell surface are screened using solid phase based assays, for example assays using magnetic beads, e.g., supplied by Dynal, preferably in a high through put manner for binding to an FcγR, e.g., FcγRIIIA. In one embodiment, magnetic bead assays may be used to identify mutants with enhanced affinity for FcγRIIIA and/or reduced affinity for FcγRIIB. An exemplary assay to identify mutants with enhanced affinity for FcγRIIIA and reduced affinity for FcγRIIB may comprise selecting mutants by a sequential solid phase depletion using magnetic beads coated with FcγRIIB followed by selection with magnetic beads coated with FcγRIIIA. For example one assay may comprise the following steps: incubating the library of yeast cells generated in accordance with the methods of the invention with magnetic beads coated with FcγRIIB; separating yeast cells bound to beads from the non bound fraction by placing the mixture in a magnetic field, removing the non-bound yeast cells and placing them in a fresh media; binding the yeast cells to beads coated with FcγRIIIA, separating yeast cells bound to beads from the non bound fraction by placing the mixture in a magnetic field, removing the non-bound yeast cells; removing the bound cells by rigorous vortexing; growing the recovered cells in glucose containing media; re-inducing in selective media containing galactose. The selection process is repeated at least once. Inserts containing the Fc domain are then amplified using common methodologies known in the art, e.g., PCR, and introduced into an antibody by methods already described for further characterization.

[0382] In an alternative embodiment, a non-yeast based system is used to characterize the binding properties of the molecules of the invention. One exemplary system for characterizing the molecules of the invention comprises a mammalian expression vector containing the heavy chain of the anti-fluorescein monoclonal antibody 4-4-20, into which the nucleic acids encoding the molecules of the invention with variant Fc regions are cloned. The resulting recombinant clone is expressed in a mammalian host cell line (i.e., human kidney cell line 293H), and the resulting recombinant immunoglobulin is analyzed for binding to FcγR using any standard assay known to those in the art, including but not limited to ELISA and FACS.

[0383] Molecules of the present invention (e.g., antibodies, fusion proteins, conjugated molecules) may be characterized in a variety of ways. In particular, molecules of the invention comprising modified Fc regions may be assayed for the ability to immunospecifically bind to a ligand, e.g., FcγRIIIA tetrameric complex. Such an assay may be performed in solution (e.g., Houghten, Bio/Techniques, 13:412-421, 1992), on beads (Lam, Nature, 354:82-84, 1991, on chips (Fodor, Nature, 364:555-556, 1993), on bacteria (U.S. Pat. No. 5,223,409), on spores (U.S. Pat. Nos. 5,571,698; 5,403,484; and 5,223,409), on plasmids (Cull et al., Proc. Natl. Acad. Sci. USA, 89:1865-1869, 1992) or on phage (Scott and Smith, Science, 249:386-390, 1990; Devlin, Science, 249:404-406, 1990; Cwirla et al., Proc. Natl. Acad. Sci. USA, 87:6378-6382, 1990; and Felici, J. Mol. Biol., 222:301-310, 1991) (each of these references is incorporated by reference herein in its entirety). Molecules that have been identified to immunospecifically bind to an ligand, e.g., FcγRIIIA can then be assayed for their specificity and affinity for the ligand.

[0384] Molecules of the invention that have been engineered to comprise modified Fc regions (e.g., therapeutic antibodies) or have been identified in the yeast display system to have the desired phenotype (see Section 5.1) may be assayed for immunospecific binding to an antigen (e.g., cancer antigen and cross-reactivity with other antigens (e.g., FcγR) by any method known in the art. Immunoassays which can be used to analyze immunospecific binding and cross-reactivity include, but are not limited to, competitive and non-competitive assay systems using techniques such as western blots, radioimmunoassays, ELISA (enzyme linked immunosorbent assay), “sandwich” immunoassays, immunoprecipitation assays, precipitin reactions, gel diffusion precipitin reactions, immunodiffusion assays, agglutination assays, complement-fixation assays, immunoradiometric assays, fluorescent immunoassays, protein A immunoassays, to name but a few. Such assays are routine and well known in the art (see, e.g., Ausubel et al., eds, 1994, Current Protocols in Molecular Biology, Vol. 1, John Wiley & Sons, Inc., New York, which is incorporated by reference herein in its entirety).

[0385] The binding affinity of the molecules of the present invention comprising modified Fc regions to a ligand, e.g., FcγR tetrameric complex and the off-rate of the interaction can be determined by competitive binding assays. One example of a competitive binding assay is a radioimmunoassay comprising the incubation of labeled ligand, such as tetrameric FcγR (e.g., ³H or ¹²⁵I) with a molecule of interest (e.g., molecules of the present invention comprising modified Fc regions) in the presence of increasing amounts of unlabeled ligand, such as tetrameric FcγR, and the detection of the molecule bound to the labeled ligand. The affinity of the molecule of the present invention for the ligand and the binding off-rates can be determined from the saturation data by scatchard analysis.

[0386] In a preferred embodiment, BIAcore kinetic analysis is used to determine the binding on and off rates of molecules of the present invention to a ligand such as FcγR. BIAcore kinetic analysis comprises analyzing the binding and dissociation of a ligand from chips with immobilized molecules (e.g., molecules comprising modified Fc regions) on their surface.

[0387] 5.2.6 Sequencing of Mutants

[0388] Any of a variety of sequencing reactions known in the art can be used to directly sequence the molecules of the invention comprising variant Fc regions. Examples of sequencing reactions include those based on techniques developed by Maxim and Gilbert (Proc. Natl. Acad. Sci. USA, 74:560, 1977) or Sanger (Proc. Natl. Acad. Sci. USA, 74:5463, 1977). It is also contemplated that any of a variety of automated sequencing procedures can be utilized (Bio/Techniques, 19:448, 1995), including sequencing by mass spectrometry (see, e.g., PCT Publication No. WO 94/16101, Cohen et al., Adv. Chromatogr., 36:127-162, 1996, and Griffin et al., Appl. Biochem. Biotechnol., 38:147-159, 1993).

[0389] 5.2.7 Functional Assays of Molecules with Variant Fc Regions

[0390] The invention encompasses characterization of the molecules of the invention (e.g., an antibody comprising a variant Fc region identified by the yeast display technology described supra; or therapeutic monoclonal antibodies engineered according to the methods of the invention) using assays known to those skilled in the art for identifying the effector cell function of the molecules. In particular, the invention encompasses characterizing the molecules of the invention for FcγR-mediated effector cell function. Examples of effector cell functions that can be assayed in accordance with the invention, include but are not limited to, antibody-dependent cell mediated cytotoxicity, phagocytosis, opsonization, opsonophagocytosis, C1q binding, and complement dependent cell mediated cytotoxicity. Any cell-based or cell free assay known to those skilled in the art for determining effector cell function activity can be used (For effector cell assays, see Perussia et al., 2000, Methods Mol. Biol. 121: 179-92; Baggiolini et al., 1998 Experientia, 44(10): 841-8; Lehmann et al., 2000 J. Immunol. Methods, 243(1-2): 229-42; Brown E J. 1994, Methods Cell Biol., 45: 147-64; Munn et al., 1990 J. Exp. Med, 172: 231-237, Abdul-Majid et al., 2002 Scand. J. Immunol. 55: 70-81; Ding et al., 1998, Immunity 8:403-411, each of which is incorporated by reference herein in its entirety).

[0391] In one embodiment, the molecules of the invention can be assayed for FcγR-mediated phagocytosis in human monocytes. Alternatively, the FcγR-mediated phagocytosis of the molecules of the invention may be assayed in other phagocytes, e.g., neutrophils (polymorphonuclear leuckocytes; PMN); human peripheral blood monocytes, monocyte-derived macrophages, which can be obtained using standard procedures known to those skilled in the art (e.g., see Brown E J. 1994, Methods Cell Biol., 45: 147-164). In one embodiment, the function of the molecules of the invention is characterized by measuring the ability of THP-1 cells to phagocytose fluoresceinated IgG-opsonized sheep red blood cells (SRBC) by methods previously described (Tridandapani et al., 2000, J. Biol. Chem. 275: 20480-7). For example, an exemplary assay for measuring phagocytosis of the molecules of the invention comprising variant Fc regions with enhanced affinities for FcγRIIIA, comprises of: treating THP-1 cells with a molecule of the invention or with a control antibody that does not bind to FcγRIIIA, comparing the activity levels of said cells, wherein a difference in the activities of the cells (e.g., rosetting activity (the number of THP-1 cells binding IgG-coated SRBC), adherence activity (the total number of SRBC bound to THP-1 cells), and phagocytic rate) would indicate the functionality of the molecule of the invention. It can be appreciated by one skilled in the art that this exemplary assay can be used to assay any of the molecules identified by the methods of the invention.

[0392] Another exemplary assay for determining the phagocytosis of the molecules of the invention is an antibody-dependent opsonophagocytosis assay (ADCP) which can comprise the following: coating a target bioparticle such as Escherichia coli-labeled FITC (Molecular Probes) or Staphylococcus aureus-FITC with (i) wild-type 4-4-20 antibody, an antibody to fluorescein (See Bedzyk et al., 1989, J. Biol. Chem, 264(3): 1565-1569, which is incorporated herein by reference in its entirety), as the control antibody for FcγR-dependent ADCP; or (ii) 4-4-20 antibody harboring the D265A mutation that knocks out binding to FcγRIII, as a background control for FcγR-dependent ADCP (iii) 4-4-20 antibody carrying variant Fc regions identified by the methods of the invention and produced as exemplified in Example 6.6; and forming the opsonized particle; adding any of the osponized particles described (i-iii) to THP-1 effector cells (a monocytic cell line available from ATCC) in a 60:1 ratio to allow FcγR-mediated phagocytosis to occur; preferably incubating the cells and E. coli-FITC/antibody at 37° C. for 1.5 hour; adding trypan blue after incubation (preferably at room temperature for 2-3 min.) to the cells to quench the fluorescence of the bacteria that are adhered to the outside of the cell surface without being internalized; transferring cells into a FACS buffer (e.g., 0.1%, BSA in PBS, 0.1%, sodium azide), analyzing the fluorescence of the THP1 cells using FACS (e.g., BD FACS Calibur). Preferably, the THP-1 cells used in the assay are analyzed by FACS for expression of FcγR on the cell surface. THP-1 cells express both CD32A and CD64. CD64 is a high affinity FcγR that is blocked in conducting the ADCP assay in accordance with the methods of the invention. The THP-1 cells are preferably blocked with 100 μg/mL soluble IgG1 or 10% human serum. To analyze the extent of ADCP, the gate is preferably set on THP-1 cells and median fluorescence intensity is measured. The ADCP activity for individual mutants is calculated and reported as a normalized value to the wild type chMab 4-4-20 obtained. The opsonized particles are added to THP-1 cells such that the ratio of the opsonized particles to THP-1 cells is 30:1 or 60:1. In most preferred embodiments, the ADCP assay is conducted with controls, such as E. coli-FITC in medium, E. coli-FITC and THP-1 cells (to serve as FcγR-independent ADCP activity), E. coli-FITC, THP-1 cells and wild-type 4-4-20 antibody (to serve as FcγR-dependent ADCP activity), E. coli-FITC, THP-1 cells, 4-4-20 D265A (to serve as the background control for FcγR-dependent ADCP activity).

[0393] In another embodiment, the molecules of the invention can be assayed for FcγR-mediated ADCC activity in effector cells, e.g., natural killer cells, using any of the standard methods known to those skilled in the art (See e.g., Perussia et al., 2000, Methods Mol. Biol. 121: 179-92). An exemplary assay for determining ADCC activity of the molecules of the invention is based on a ⁵¹Cr release assay comprising of: labeling target cells with [⁵¹Cr]Na₂CrO₄ (this cell-membrane permeable molecule is commonly used for labeling since it binds cytoplasmic proteins and although spontaneously released from the cells with slow kinetics, it is released massively following target cell necrosis); osponizing the target cells with the molecules of the invention comprising variant Fc regions; combining the opsonized radiolabeled target cells with effector cells in a microtitre plate at an appropriate ratio of target cells to effector cells; incubating the mixture of cells for 16-18 hours at 37° C.; collecting supernatants; and analzying radioactivity. The cytotoxicity of the molecules of the invention can then be determined, for example using the following formula: % lysis=(experimental cpm−target leak cpm)/(detergent lysis cpm−target leak cpm)×100%. Alternatively, % lysis=(ADCC−AICC)/(maximum release−spontaneous release). Specific lysis can be calculated using the formula: specific lysis=% lysis with the molecules of the invention−% lysis in the absence of the molecules of the invention. A graph can be generated by varying either the target: effector cell ratio or antibody concentration.

[0394] In yet another embodiment, the molecules of the invention are characterized for antibody dependent cellular cytotoxicity (ADCC) see, e.g., Ding et al., Immunity, 1998, 8:403-11; which is incorporated herein by reference in its entirety.

[0395] Preferably, the effector cells used in the ADCC assays of the invention are peripheral blood mononuclear cells (PBMC) that are preferably purified from normal human blood, using standard methods known to one skilled in the art, e.g., using Ficoll-Paque density gradient centrifugation. Preferred effector cells for use in the methods of the invention express different FcγR activating receptors. The invention encompasses, effector cells, THP-1, expressing FcγRI, FcγRIIA and FcγRIIB, and monocyte derived primary macrophages derived from whole human blood expressing both FcγRIIIA and FcγRIIB, to determine if Fc antibody mutants show increased ADCC activity and phagocytosis relative to wild type IgG1 antibodies.

[0396] The human monocyte cell line, THP-1, activates phagocytosis through expression of the high affinity receptor FcγRI and the low affinity receptor FcγRIIA (Fleit et al., 1991, J. Leuk. Biol. 49: 556). THP-1 cells do not constitutively express FcγRIIA or FcγRIIB. Stimulation of these cells with cytokines effects the FcR expression pattern (Pricop et al., 2000 J. Immunol. 166: 531-7). Growth of THP-1 cells in the presence of the cytokine IL4 induces FcγRIIB expression and causes a reduction in FcγRIIA and FcγRI expression. FcγRIIB expression can also be enhanced by increased cell density (Tridandapani et al., 2002, J. Biol. Chem. 277: 5082-9). In contrast, it has been reported that IFNγ can lead to expression of FcγRIIIA (Pearse et al., 1993 PNAS USA 90: 4314-8). The presence or absence of receptors on the cell surface can be determined by FACS using common methods known to one skilled in the art. Cytokine induced expression of FcγR on the cell surface provides a system to test both activation and inhibition in the presence of FcγRIIB. If THP-1 cells are unable to express the FcγRIIB the invention also encompasses another human monocyte cell line, U937. These cells have been shown to terminally differentiate into macrophages in the presence of IFNγ and TNF (Koren et al., 1979, Nature 279: 328-331).

[0397] FcγR dependent tumor cell killing is mediated by macrophage and NK cells in mouse tumor models (Clynes et al., 1998, PNAS USA 95: 652-656). The invention encompasses the use of elutriated monocytes from donors as effector cells to analyze the efficiency Fc mutants to trigger cell cytotoxicity of target cells in both phagocytosis and ADCC assays. Expression patterns of FcγRI, FcγRIIIA, and FcγRIIB are affected by different growth conditions. FcγR expression from frozen elutriated monocytes, fresh elutriated monocytes, monocytes maintained in 10% FBS, and monocytes cultured in FBS+GM-CSF and or in human serum may be determined using common methods known to those skilled in the art. For example, cells can be stained with FcγR specific antibodies and analyzed by FACS to determine FcR profiles. Conditions that best mimic macrophage in vivo FcγR expression is then used for the methods of the invention.

[0398] In some embodiments, the invention encompasses the use of mouse cells especially when human cells with the right FcγR profiles are unable to be obtained. In some embodiments, the invention encompasses the mouse macrophage cell line RAW264.7(ATCC) which can be transfected with human FcγRIIIA and stable transfectants isolated using methods known in the art, see, e.g., Ralph et al., J. Immunol. 1119: 950-4). Transfectants can be quantitated for FcγRIIIA expression by FACS analysis using routine experimentation and high expressors can be used in the ADCC assays of the invention. In other embodiments, the invention encompasses isolation of spleen peritoneal macrophage expressing human FcγR from knockout transgenic mice such as those disclosed herein.

[0399] Lymphocytes may be harvested from peripheral blood of donors (PBM) using a Ficoll-Paque gradient (Pharmacia). Within the isolated mononuclear population of cells the majority of the ADCC activity occurs via the natural killer cells (NK) containing FcγRIIIA but not FcγRIIB on their surface. Results with these cells indicate the efficacy of the mutants on triggering NK cell ADCC and establish the reagents to test with elutriated monocytes.

[0400] Target cells used in the ADCC assays of the invention include, but are not limited to, breast cancer cell lines, e.g., SK-BR-3 with ATCC accession number HTB-30 (see, e.g., Tremp et al., 1976, Cancer Res. 33-41); B-lymphocytes; cells derived from Burkitts lymphoma, e.g., Raji cells with ATCC accession number CCL-86 (see, e.g., Epstein et al., 1965, J. Natl. Cancer Inst. 34: 231-240), and Daudi cells with ATCC accession number CCL-213 (see, e.g., Klein et al., 1968, Cancer Res. 28: 1300-10). The target cells must be recognized by the antigen binding site of the immunoglobulin to be assayed.

[0401] The ADCC assay is based on the ability of NK cells to mediate cell death via an apoptotic pathway. NK cells mediate cell death in part by FcγRIIIA's recognition of IgG bound to an antigen on a cell surface. The ADCC assays used in accordance with the methods of the invention may be radioactive based assays or fluorescence based assays. The ADCC assay used to characterize the molecules of the invention comprising variant Fc regions comprises labeling target cells, e.g., SK-BR-3, MCF-7, OVCAR3, Raji, Daudi cells, opsonizing target cells with an antibody that recognizes a cell surface receptor on the target cell via its antigen binding site; combining the labeled opsonized target cells and the effector cells at an appropriate ratio, which can be determined by routine experimentation; harvesting the cells; detecting the label in the supernatant of the lysed target cells, using an appropriate detection scheme based on the label used. The target cells may be labeled either with a radioactive label or a fluorescent label, using standard methods known in the art. For example the labels include, but are not limited to, [⁵¹Cr]Na₂CrO₄; and the acetoxymethyl ester of the fluorescence enhancing ligand, 2,2′:6′,2″-terpyridine-6-6″-dicarboxylate (TDA).

[0402] In a specific preferred embodiment, a time resolved fluorimetric assay is used for measuring ADCC activity against target cells that have been labeled with the acetoxymethyl ester of the fluorescence enhancing ligand, 2,2′:6′,2″-terpyridine-6-6″-dicarboxylate (TDA). Such fluorimetric assays are known in the art, e.g., see, Blomberg et al., 1996, Journal of Immunological Methods, 193: 199-206; which is incorporated herein by reference in its entirety. Briefly, target cells are labeled with the membrane permeable acetoxymethyl diester of TDA (bis(acetoxymethyl) 2,2′:6′,2″-terpyridine-6-6″-dicarboxylate, (BATDA), which rapidly diffuses across the cell membrane of viable cells. Intracellular esterases split off the ester groups and the regenerated membrane impermeable TDA molecule is trapped inside the cell. After incubation of effector and target cells, e.g., for at least two hours, up to 3.5 hours, at 37° C., under 5% CO₂, the TDA released from the lysed target cells is chelated with Eu3+ and the fluorescence of the Europium-TDA chelates formed is quantitated in a time-resolved fluorometer (e.g., Victor 1420, Perkin Elmer/Wallac).

[0403] In another specific embodiment, the ADCC assay used to characterize the molecules of the invention comprising variant Fc regions comprises the following steps: Preferably 4-5×10⁶ target cells (e.g., SK-BR-3, MCF-7, OVCAR3, Raji cells) are labeled with bis(acetoxymethyl) 2,2′:6′,2″-terpyridine-t-6″-dicarboxylate (DELFIA BATDA Reagent, Perkin Elmer/Wallac). For optimal labeling efficiency, the number of target cells used in the ADCC assay should preferably not exceed 5×10⁶. BATDA reagent is added to the cells and the mixture is incubated at 37° C. preferably under 5% CO₂, for at least 30 minutes. The cells are then washed with a physiological buffer, e.g., PBS with 0.125 mM sulfinpyrazole, and media containing 0.125 mM sulfinpyrazole. The labeled target cells are then opsonized (coated) with a molecule of the invention comprising a variant Fc region, i.e., an immunoglobulin comprising a variant Fc region of the invention, including, but not limited to, a polyclonal antibody, a monoclonal antibody, a bispecific antibody, a multi-specific antibody, a humanized antibody, or a chimeric antibody. In preferred embodiments, the immunoglobulin comprising a variant Fc region used in the ADCC assay is specific for a cell surface receptor, a tumor antigen, or a cancer antigen. The immunoglobulin into which a variant Fc region of the invention is introduced may specifically bind any cancer or tumor antigen, such as those listed in section 5.4. Additionally, the immunoglobulin into which a variant Fc region of the invention is introduced may be any therapeutic antibody specific for a cancer antigen, such as those listed in section 5.4. In some embodiments, the immunoglobulin comprising a variant Fc region used in the ADCC assay is an anti-fluoresceine monoclonal antibody, 4-4-20 (Kranz et al., 1982 J. Biol. Chem. 257(12): 6987-6995) a mouse-human chimeric anti-CD20 monoclonal antibody 2H7 (Liu et al., 1987, Journal of Immunology, 139: 3521-6); or a humanized antibody (Ab4D5) against the human epidermal growth factor receptor 2 (p185 HER2) (Carter et al. (1992, Proc. Natl. Acad. Sci. USA 89: 4285-9). The target cells in the ADCC assay are chosen according to the immunoglobulin into which a variant Fc region of the invention has been introduced so that the immunoglobulin binds a cell surface receptor of the target cell specifically. Preferably, the ADCC assays of the invention are performed using more than one engineered antibody, e.g., anti Her2/neu, 4-4-20, 2B6, Rituxan, and 2H7, harboring the Fc variants of the invention. In a most preferred embodiment, the Fc variants of the invention are introduced into at least 3 antibodies and their ADCC activities are tested. Although not intending to be bound by a particular mechanism of action, examining at least 3 antibodies in these functional assays will diminish the chance of eliminating a viable Fc mutation erroneously.

[0404] Opsonized target cells are added to effector cells, e.g., PBMC, to produce effector:target ratios of approximately 50:1, 75:1, or 100:1. In a specific embodiment, when the immunoglobulin comprising a variant Fc region has the variable domain of 4-4-20, the effector:target is 75:1. The effector and target cells are incubated for at least two hours, up to 3.5 hours, at 37° C., under 5% CO₂. Cell supernatants are harvested and added to an acidic europium solution (e.g., DELFIA Europium Solution, Perkin Elmer/Wallac). The fluorescence of the Europium-TDA chelates formed is quantitated in a time-resolved fluorometer (e.g., Victor 1420, Perkin Elmer/Wallac). Maximal release (MR) and spontaneous release (SR) are determined by incubation of target cells with 1% TX-100 and media alone, respectively. Antibody independent cellular cytotoxicity (AICC) is measured by incubation of target and effector cells in the absence of antibody. Each assay is preferably performed in triplicate. The mean percentage specific lysis is calculated as: Experimental release(ADCC)−AICC)/(MR−SR)×100.

[0405] The invention encompasses characterization of the Fc variants in both NK-dependent and macrophage dependent ADCC assays. Fc variants of the invention have altered phenotypes such as an altered effector function as assayed in an NK dependent or macrophage dependent assay.

[0406] The invention encompasses assays known in the art and exemplified herein, to bind C1q and mediate complement dependent cytotoxicity (CDC). To determine C1q binding, a C1q binding ELISA may be performed. An exemplary assay may comprise the following: assay plates may be coated overnight at 4C with polypeptide variant or starting polypeptide (control) in coating buffer. The plates may then be washed and blocked. Following washing, an aliquot of human C1q may be added to each well and incubated for 2 hrs at room temperature. Following a further wash, 100 uL of a sheep anti-complement C1q peroxidase conjugated antibody may be added to each well and incubated for 1 hour at room temperature. The plate may again be washed with wash buffer and 100 ul of substrate buffer containing OPD (O-phenylenediamine dihydrochloride (Sigma)) may be added to each well. The oxidation reaction, observed by the appearance of a yellow color, may be allowed to proceed for 30 minutes and stopped by the addition of 100 ul of 4.5 NH2 SO4. The absorbance may then read at (492-405) nm.

[0407] A preferred variant in accordance with the invention is one that displays a significant reduction in C1q binding, as detected and measured in this assay or a similar assay. Preferably the molecule comprising an Fc variant displays about 50 fold reduction, about 60 fold, about 80 fold, or about 90 fold reduction in C1q binding compared to a control antibody having a nonmutated IgG1 Fc region. In the most preferred embodiment, the molecule comprising an Fc variant does not bind C1q, i.e. the variant displays about 100 fold or more reduction in C1q binding compared to the control antibody.

[0408] Another exemplary variant is one which has a better binding affinity for human C1q than the molecule comprising wild type Fc region. Such a molecule may display, for example, about two-fold or more, and preferably about five-fold or more, improvement in human C1q binding compared to the parent molecule comprising wild type Fc region. For example, human C1q binding may be about two-fold to about 500-fold, and preferably from about two-fold or from about five-fold to about 1000-fold improved compared to the molecule comprising wild type Fc region.

[0409] To assess complement activation, a complement dependent cytotoxicity (CDC) assay may be performed, e.g. as described in Gazzano-Santoro et al., J. Immunol. Methods 202:163 (1996), which is incorporated herein by reference in its entirety. Briefly, various concentrations of the molecule comprising a variant Fc region and human complement may be diluted with buffer. Cells which express the antigen to which the molecule comprising a variant Fc region binds may be diluted to a density of about 1×10⁶ cells/ml. Mixtures of the molecule comprising a variant Fc region, diluted human complement and cells expressing the antigen may be added to a flat bottom tissue culture 96 well plate and allowed to incubate for 2 hrs at 37 C. and 5% CO2 to facilitate complement mediated cell lysis. 50 uL of alamar blue (Accumed International) may then be added to each well and incubated overnight at 37 C. The absorbance is measured using a 96-well fluorometer with excitation at 530 nm and emission at 590 nm. The results may be expressed in relative fluorescence units (RFU). The sample concentrations may be computed from a standard curve and the percent activity as compared to nonvariant molecule, i.e., a molecule comprising wild type Fc region, is reported for the variant of interest.

[0410] In some embodiments, an Fc variant of the invention does not activate complement Preferably the variant does not appear to have any CDC activity in the above CDC assay. The invention also pertains to a variant with enhanced CDC compared to a parent molecule (a molecule comprising wild type Fc region), e.g., displaying about two-fold to about 100-fold improvement in CDC activity in vitro or in vivo (e.g., at the IC50 values for each molecule being compared). Complement assays may be performed with guinea pig, rabbit or human serum. Complement lysis of target cells may be detected by monitoring the release of intracellular enzymes such as lactate dehydrogenase (LDH), as described in Korzeniewski et al., 1983 Immunol. Methods 64(3): 313-20; and Decker et al., 1988 J Immunol Methods 115(1): 61-9, each of which is incorporated herein by reference in its entirety; or the release of an intracellular label such as europium, chromium 51 or indium 111 in which target cells are labeled as described herein.

[0411] 5.2.8 Other Assays

[0412] The molecules of the invention comprising variant Fc regions may also be assayed using any surface plasmon resonance based assays known in the art for characterizing the kinetic parameters of Fc-FcγR interaction binding. Any SPR instrument commercially available including, but not limited to, BIAcore Instruments, available from Biacore AB (Uppsala, Sweden); IAsys instruments available from Affinity Sensors (Franklin, Mass.); IBIS system available from Windsor Scientific Limited (Berks, UK), SPR-CELLIA systems available from Nippon Laser and Electronics Lab (Hokkaido, Japan), and SPR Detector Spreeta available from Texas Instruments (Dallas, Tex.) can be used in the instant invention. For a review of SPR-based technology see Mullet et al., 2000, Methods 22: 77-91; Dong et al., 2002, Review in Mol. Biotech., 82: 303-23; Fivash et al., 1998, Current Opinion in Biotechnology 9: 97-101; Rich et al., 2000, Current Opinion in Biotechnology 11: 54-61; all of which are incorporated herein by reference in their entirety. Additionally, any of the SPR instruments and SPR based methods for measuring protein-protein interactions described in U.S. Pat. Nos. 6,373,577; 6,289,286; 5,322,798; 5,341,215; 6,268,125 are contemplated in the methods of the invention, all of which are incorporated herein by reference in their entirety.

[0413] Briefly, SPR based assays involve immobilizing a member of a binding pair on a surface, and monitoring its interaction with the other member of the binding pair in solution in real time. SPR is based on measuring the change in refractive index of the solvent near the surface that occurs upon complex formation or dissociation. The surface onto which the immobilization occur is the sensor chip, which is at the heart of the SPR technology; it consists of a glass surface coated with a thin layer of gold and forms the basis for a range of specialized surfaces designed to optimize the binding of a molecule to the surface. A variety of sensor chips are commercially available especially from the companies listed supra, all of which may be used in the methods of the invention. Examples of sensor chips include those available from BIAcore AB, Inc., e.g., Sensor Chip CM5, SA, NTA, and HPA. A molecule of the invention may be immobilized onto the surface of a sensor chip using any of the immobilization methods and chemistries known in the art, including but not limited to, direct covalent coupling via amine groups, direct covalent coupling via sulfhydryl groups, biotin attachment to avidin coated surface, aldehyde coupling to carbohydrate groups, and attachment through the histidine tag with NTA chips.

[0414] In some embodiments, the kinetic parameters of the binding of molecules of the invention comprising variant Fc regions, e.g., immunoglobulins comprising variant Fc region, to an FcγR may be determined using a BIAcore instrument (e.g., BIAcore instrument 1000, BIAcore Inc., Piscataway, N.J.). Any FcγR can be used to assess the interaction with the molecules of the invention comprising variant Fc regions. In a specific embodiment the FcγR is FcγRIIIA, preferably a soluble monomeric FcγRIIIA. For example, in one embodiment, the soluble monomeric FcγRIIIA is the extracellular region of FcγRIIIA joined to the linker-AVITAG sequence (see, U.S. Provisional Application No. 60/439,498, filed on Jan. 9, 2003 (Attorney Docket No. 11183-004-888) and U.S. Provisional Application No. 60/456,041 filed on Mar. 19, 2003, which are incorporated herein by reference in their entireties). In another specific embodiment, the FcγR is FcγRIIB, preferably a soluble dimeric FcγRIIB. For example in one embodiment, the soluble dimeric FcγRIIB protein is prepared in accordance with the methodology described in U.S. Provisional application No. 60/439,709 filed on Jan. 13, 2003, which is incorporated herein by reference in its entirety.

[0415] An exemplary assay for determining the kinetic parameters of a molecule comprising a variant Fc region, wherein the molecule is the 4-4-20 antibody, to an FcγR using a BIAcore instrument comprises the following: BSA-FITC is immobilized on one of the four flow cells of a sensor chip surface, preferably through amine coupling chemistry such that about 5000 response units (RU) of BSA-FITC is immobilized on the surface. Once a suitable surface is prepared, 4-4-20 antibodies carrying the Fc mutations are passed over the surface, preferably by one minute injections of a 20 μg/mL solution at a 5 μL/mL flow rate. The level of 4-4-20 antibodies bound to the surface ranges between 400 and 700 RU. Next, dilution series of the receptor (FcγRIIA and FcγRIIB-Fc fusion protein) in HBS-P buffer (20 mM HEPES, 150 mM NaCl, 3 mM EDTA, pH 7.5) are injected onto the surface at 100 μL/min Antibody regeneration between different receptor dilutions is carried out preferably by single 5 second injections of 100 mM NaHCO₃ pH 9.4; 3M NaCl. Any regeneration technique known in the art is contemplated in the method of the invention.

[0416] Once an entire data set is collected, the resulting binding curves are globally fitted using computer algorithms supplied by the SPR instrument manufacturer, e.g., BIAcore, Inc. (Piscataway, N.J.). These algorithms calculate both the K_on and K_off, from which the apparent equilibrium binding constant, K_d is deduced as the ratio of the two rate constants (i.e., K_off/K_on). More detailed treatments of how the individual rate constants are derived can be found in the BIAevaluaion Software Handbook (BIAcore, Inc., Piscataway, N.J.). The analysis of the generated data may be done using any method known in the art. For a review of the various methods of interpretation of the kinetic data generated see Myszka, 1997, Current Opinion in Biotechnology 8: 50-7; Fisher et al., 1994, Current Opinion in Biotechnology 5: 389-95; O'Shannessy, 1994, Current Opinion in Biotechnology, 5:65-71; Chaiken et al., 1992, Analytical Biochemistry, 201: 197-210; Morton et al., 1995, Analytical Biochemistry 227: 176-85; O'Shannessy et al., 1996, Analytical Biochemistry 236: 275-83; all of which are incorporated herein by reference in their entirety.

[0417] In preferred embodiments, the kinetic parameters determined using an SPR analysis, e.g., BIAcore, may be used as a predictive measure of how a molecule of the invention will function in a functional assay, e.g., ADCC. An exemplary method for predicting the efficacy of a molecule of the invention based on kinetic parameters obtained from an SPR analysis may comprise the following: determining the K_off values for binding of a molecule of the invention to FcγRIIIA and FcγRIIB; plotting (1) K_off (wt)/K_off (mut) for FcγRIIIA; (2) K_off (mut)/K_off (wt) for FcγRIIB against the ADCC data. Numbers higher than one show a decreased dissociation rate for FcγRIIIA and an increased dissociation rate for FcγRIIB relative to wild tyoe; and possess and enhanced ADCC function.

[0418] 5.3 Methods of Recombinantly Producing Molecules of the Invention

[0419] 5.3.1 Polynucleotides Encoding Molecules of the Invention

[0420] The present invention also includes polynucleotides that encode the molecules, including the polypeptides and antibodies, of the invention identified by the methods of the invention. The polynucleotides encoding the molecules of the invention may be obtained, and the nucleotide sequence of the polynucleotides determined, by any method known in the art.

[0421] Once the nucleotide sequence of the molecules (e.g., antibodies) that are identified by the methods of the invention is determined, the nucleotide sequence may be manipulated using methods well known in the art, e.g., recombinant DNA techniques, site directed mutagenesis, PCR, etc. (see, for example, the techniques described in Sambrook et al., 2001, Molecular Cloning, A Laboratory Manual, 3rd Ed., Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.; and Ausubel et al., eds., 1998, Current Protocols in Molecular Biology, John Wiley & Sons, NY, which are both incorporated by reference herein in their entireties), to generate, for example, antibodies having a different amino acid sequence, for example by generating amino acid substitutions, deletions, and/or insertions.

[0422] In a specific embodiment, when the nucleic acids encode antibodies, one or more of the CDRs are inserted within framework regions using routine recombinant DNA techniques. The framework regions may be naturally occurring or consensus framework regions, and preferably human framework regions (see, e.g., Chothia et al., 1998, J. Mol. Biol. 278: 457-479 for a listing of human framework regions).

[0423] In another embodiment, human libraries or any other libraries available in the art, can be screened by standard techniques known in the art, to clone the nucleic acids encoding the molecules of the invention.

[0424] 5.3.2 Recombinant Expression of Molecules of the Invention

[0425] Once a nucleic acid sequence encoding molecules of the invention (i.e., antibodies) has been obtained, the vector for the production of the molecules may be produced by recombinant DNA technology using techniques well known in the art. Methods which are well known to those skilled in the art can be used to construct expression vectors containing the coding sequences for the molecules of the invention and appropriate transcriptional and translational control signals. These methods include, for example, in vitro recombinant DNA techniques, synthetic techniques, and in vivo genetic recombination. (See, for example, the techniques described in Sambrook et al., 1990, Molecular Cloning, A Laboratory Manual, 2d Ed., Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y. and Ausubel et al. eds., 1998, Current Protocols in Molecular Biology, John Wiley & Sons, NY).

[0426] An expression vector comprising the nucleotide sequence of a molecule identified by the methods of the invention (i.e., an antibody) can be transferred to a host cell by conventional techniques (e.g., electroporation, liposomal transfection, and calcium phosphate precipitation) and the transfected cells are then cultured by conventional techniques to produce the molecules of the invention. In specific embodiments, the expression of the molecules of the invention is regulated by a constitutive, an inducible or a tissue, specific promoter.

[0427] The host cells used to express the molecules identified by the methods of the invention may be either bacterial cells such as Escherichia coli, or, preferably, eukaryotic cells, especially for the expression of whole recombinant immunoglobulin molecule. In particular, mammalian cells such as Chinese hamster ovary cells (CHO), in conjunction with a vector such as the major intermediate early gene promoter element from human cytomegalovirus is an effective expression system for immunoglobulins (Foecking et al., 1998, Gene 45:101; Cockett et al., 1990, Bio/Technology 8:2).

[0428] A variety of host-expression vector systems may be utilized to express the molecules identified by the methods of the invention. Such host-expression systems represent vehicles by which the coding sequences of the molecules of the invention may be produced and subsequently purified, but also represent cells which may, when transformed or transfected with the appropriate nucleotide coding sequences, express the molecules of the invention in situ. These include, but are not limited to, microorganisms such as bacteria (e.g., E. coli and B. subtilis) transformed with recombinant bacteriophage DNA, plasmid DNA or cosmid DNA expression vectors containing coding sequences for the molecules identified by the methods of the invention; yeast (e.g., Saccharomyces Pichia) transformed with recombinant yeast expression vectors containing sequences encoding the molecules identified by the methods of the invention; insect cell systems infected with recombinant virus expression vectors (e.g., baculovirus) containing the sequences encoding the molecules identified by the methods of the invention; plant cell systems infected with recombinant virus expression vectors (e.g., cauliflower mosaic virus (CaMV) and tobacco mosaic virus (TMV) or transformed with recombinant plasmid expression vectors (e.g., Ti plasmid) containing sequences encoding the molecules identified by the methods of the invention; or mammalian cell systems (e.g., COS, CHO, BHK, 293, 293T, 3T3 cells, lymphotic cells (see U.S. Pat. No. 5,807,715), Per C.6 cells (human retinal cells developed by Crucell) harboring recombinant expression constructs containing promoters derived from the genome of mammalian cells (e.g., metallothionein promoter) or from mammalian viruses (e.g., the adenovirus late promoter; the vaccinia virus 7.5K promoter).

[0429] In bacterial systems, a number of expression vectors may be advantageously selected depending upon the use intended for the molecule being expressed. For example, when a large quantity of such a protein is to be produced, for the generation of pharmaceutical compositions of an antibody, vectors which direct the expression of high levels of fusion protein products that are readily purified may be desirable. Such vectors include, but are not limited, to the E. coli expression vector pUR278 (Ruther et al., 1983, EMBO J. 2:1791), in which the antibody coding sequence may be ligated individually into the vector in frame with the lac Z coding region so that a fusion protein is produced; pIN vectors (Inouye & Inouye, 1985, Nucleic Acids Res. 13:3101-3109; Van Heeke & Schuster, 1989, J. Biol. Chem. 24:5503-5509); and the like. pGEX vectors may also be used to express foreign polypeptides as fusion proteins with glutathione S-transferase (GST). In general, such fusion proteins are soluble and can easily be purified from lysed cells by adsorption and binding to a matrix glutathione-agarose beads followed by elution in the presence of free gluta-thione. The pGEX vectors are designed to include thrombin or factor Xa protease cleavage sites so that the cloned target gene product can be released from the GST moiety.

[0430] In an insect system, Autographa californica nuclear polyhedrosis virus (AcNPV) is used as a vector to express foreign genes. The virus grows in Spodoptera frugiperda cells. The antibody coding sequence may be cloned individually into non-essential regions (e.g., the polyhedrin gene) of the virus and placed under control of an AcNPV promoter (e.g., the polyhedrin promoter).

[0431] In mammalian host cells, a number of viral-based expression systems may be utilized. In cases where an adenovirus is used as an expression vector, the antibody coding sequence of interest may be ligated to an adenovirus transcription/translation control complex, e.g., the late promoter and tripartite leader sequence. This chimeric gene may then be inserted in the adenovirus genome by in vitro or in vivo recombination. Insertion in a non-essential region of the viral genome (e.g., region E1 or E3) will result in a recombinant virus that is viable and capable of expressing the immunoglobulin molecule in infected hosts (e.g., see Logan & Shenk, 1984, Proc. Natl. Acad. Sci. USA 81:355-359). Specific initiation signals may also be required for efficient translation of inserted antibody coding sequences. These signals include the ATG initiation codon and adjacent sequences. Furthermore, the initiation codon must be in phase with the reading frame of the desired coding sequence to ensure translation of the entire insert. These exogenous translational control signals and initiation codons can be of a variety of origins, both natural and synthetic. The efficiency of expression may be enhanced by the inclusion of appropriate transcription enhancer elements, transcription terminators, etc. (see Bittner et al., 1987, Methods in Enzymol. 153:51-544).

[0432] In addition, a host cell strain may be chosen which modulates the expression of the inserted sequences, or modifies and processes the gene product in the specific fashion desired. Such modifications (e.g., glycosylation) and processing (e.g., cleavage) of protein products may be important for the function of the protein. Different host cells have characteristic and specific mechanisms for the post-translational processing and modification of proteins and gene products. Appropriate cell lines or host systems can be chosen to ensure the correct modification and processing of the foreign protein expressed. To this end, eukaryotic host cells which possess the cellular machinery for proper processing of the primary transcript, glycosylation, and phosphorylation of the gene product may be used. Such mammalian host cells include but are not limited to CHO, VERY, BHK, Hela, COS, MDCK, 293, 293T, 3T3, W138, BT483, Hs578T, HTB2, BT20 and T47D, CRL7030 and Hs578Bst.

[0433] For long-term, high-yield production of recombinant proteins, stable expression is preferred. For example, cell lines which stably express an antibody of the invention may be engineered. Rather than using expression vectors which contain viral origins of replication, host cells can be transformed with DNA controlled by appropriate expression control elements (e.g., promoter, enhancer, sequences, transcription terminators, polyadenylation sites, etc.), and a selectable marker. Following the introduction of the foreign DNA, engineered cells may be allowed to grow for 1-2 days in an enriched media, and then are switched to a selective media. The selectable marker in the recombinant plasmid confers resistance to the selection and allows cells to stably integrate the plasmid into their chromosomes and grow to form foci which in turn can be cloned and expanded into cell lines. This method may advantageously be used to engineer cell lines which express the antibodies of the invention. Such engineered cell lines may be particularly useful in screening and evaluation of compounds that interact directly or indirectly with the antibodies of the invention.

[0434] A number of selection systems may be used, including but not limited to the herpes simplex virus thymidine kinase (Wigler et al., 1977, Cell 11: 223), hypoxanthine-guanine phosphoribosyltransferase (Szybalska & Szybalski, 1992, Proc. Natl. Acad. Sci. USA 48: 202), and adenine phosphoribosyltransferase (Lowy et al., 1980, Cell 22: 817) genes can be employed in tk−, hgprt− or aprt− cells, respectively. Also, antimetabolite resistance can be used as the basis of selection for the following genes: dhfr, which confers resistance to methotrexate (Wigler et al., 1980, Proc. Natl. Acad. Sci. USA 77:357; O'Hare et al., 1981, Proc. Natl. Acad. Sci. USA 78: 1527); gpt, which confers resistance to mycophenolic acid (Mulligan & Berg, 1981, Proc. Natl. Acad. Sci. USA 78: 2072); neo, which confers resistance to the aminoglycoside G-418 Clinical Pharmacy 12: 488-505; Wu and Wu, 1991, 3:87-95; Tolstoshev, 1993, Ann. Rev. Pharmacol. Toxicol. 32:573-596; Mulligan, 1993, Science 260:926-932; and Morgan and Anderson, 1993, Ann. Rev. Biochem. 62:191-217; May, 1993, TIB TECH 11(5):155-215). Methods commonly known in the art of recombinant DNA technology which can be used are described in Ausubel et al (eds.), 1993, Current Protocols in Molecular Biology, John Wiley & Sons, NY; Kriegler, 1990, Gene Transfer and Expression, A Laboratory Manual, Stockton Press, NY; and in Chapters 12 and 13, Dracopoli et al. (eds), 1994, Current Protocols in Human Genetics, John Wiley & Sons, NY; Colberre-Garapin et al., 1981, J. Mol. Biol. 150:1; and hygro, which confers resistance to hygromycin (Santerre et al., 1984, Gene 30:147).

[0435] The expression levels of an antibody of the invention can be increased by vector amplification (for a review, see Bebbington and Hentschel, The use of vectors based on gene amplification for the expression of cloned genes in mammalian cells in DNA cloning, Vol. 3 (Academic Press, New York, 1987). When a marker in the vector system expressing an antibody is amplifiable, increase in the level of inhibitor present in culture of host cell will increase the number of copies of the marker gene. Since the amplified region is associated with the nucleotide sequence of the antibody, production of the antibody will also increase (Crouse et al., 1983, Mol. Cell. Biol. 3:257).

[0436] The host cell may be co-transfected with two expression vectors of the invention, the first vector encoding a heavy chain derived polypeptide and the second vector encoding a light chain derived polypeptide. The two vectors may contain identical selectable markers which enable equal expression of heavy and light chain polypeptides. Alternatively, a single vector may be used which encodes both heavy and light chain polypeptides. In such situations, the light chain should be placed before the heavy chain to avoid an excess of toxic free heavy chain (Proudfoot, 1986, Nature 322:52; Kohler, 1980, Proc. Natl. Acad. Sci. USA 77:2197). The coding sequences for the heavy and light chains may comprise cDNA or genomic DNA.

[0437] Once a molecule of the invention (i.e., antibodies) has been recombinantly expressed, it may be purified by any method known in the art for purification of polypeptides or antibodies, for example, by chromatography (e.g., ion exchange, affinity, particularly by affinity for the specific antigen after Protein A, and sizing column chromatography), centrifugation, differential solubility, or by any other standard technique for the purification of polypeptides or antibodies.

[0438] 5.4 Prophylactic and Therapeutic Methods

[0439] The present invention encompasses administering one or more of the molecules of the invention (e.g., antibodies) to an animal, preferably a mammal, and most preferably a human, for preventing, treating, or ameliorating one or more symptoms associated with a disease, disorder, or infection. The molecules of the invention are particularly useful for the treatment or prevention of a disease or disorder where an enhanced efficacy of effector cell function (e.g., ADCC) mediated by FcγR is desired. The methods and compositions of the invention are particularly useful for the treatment or prevention of primary or metastatic neoplastic disease (i.e., cancer), and infectious diseases. Molecules of the invention may be provided in pharmaceutically acceptable compositions as known in the art or as described herein. As detailed below, the molecules of the invention can be used in methods of treating or preventing cancer (particularly in passive immunotherapy), autoimmune disease, inflammatory disorders or infectious diseases.

[0440] The molecules of the invention may also be advantageously utilized in combination with other therapeutic agents known in the art for the treatment or prevention of a cancer, autoimmune disease, inflammatory disorders or infectious diseases. In a specific embodiment, molecules of the invention may be used in combination with monoclonal or chimeric antibodies, lymphokines, or hematopoietic growth factors (such as, e.g., IL-2, IL-3 and IL-7), which, for example, serve to increase the number or activity of effector cells which interact with the molecules and, increase immune response. The molecules of the invention may also be advantageously utilized in combination with one or more drugs used to treat a disease, disorder, or infection such as, for example anti-cancer agents, anti-inflammatory agents or anti-viral agents, e.g., as detailed in sections 5.4.1.2 and 5.4.2.1 below.

[0441] 5.4.1 Cancers

[0442] The invention encompasses methods and composition for treatment or prevention of cancer or metastasis in a subject comprising administering to the subject a therapeutically effective amount of one or more molecules comprising a variant Fc region.

[0443] Molecules of the invention (i.e., polypeptides, antibodies) comprising variant Fc regions can be used to prevent, inhibit or reduce the growth of primary tumors or metastasis of cancerous cells. In one embodiment, the molecule of the invention comprises a variant Fc that binds FcγRIIIA and/or FcγRIIA with a greater affinity than a comparable polypeptide comprising a wild type Fc region binds FcγRIIIA and/or FcγRIIA, and/or said variant Fc region has an enhanced effector function, e.g., ADCC, CDC, phagocytosis, opsonization, etc. Such molecules can be used alone to treat or prevent cancer. In another embodiment, the molecule of the invention comprises a variant Fc region that binds FcγRIIIA and/or FcγRIIA with a greater affinity than a comparable polypeptide comprising a wild type Fc region binds FcγRIIIA and/or FcγRIIA, and further binds FcγRIIB with a lower affinity than a comparable polypeptide comprising a wild-type Fc region binds FcγRIIB, and/or said variant Fc region has an enhanced effector function, e.g., ADCC, CDC, phagocytosis, opsonization, etc. Such molecules can also be used alone to treat or prevent cancer.

[0444] In some embodiments, the invention encompasses methods and compositions for the treatment or prevention of cancer in a subject with FcγR polymorphisms such as those homozygous for the FγRIIIA-158V or FcγRIIIA-158F alleles. In some embodiments, the invention encompasses engineering therapeutic antibodies, e.g., tumor specific monoclonal antibodies in accordance with the methods of the invention such that the engineered antibodies have enhanced efficacy in patients homozygous for the low affinity allele of FcγRIIIA (158F). In other embodiments, the invention encompasses engineering therapeutic antibodies, e.g., tumor specific monoclonal antibodies in accordance with the methods of the invention such that the engineered antibodies have enhanced efficacy in patients homozygous for the high affinity allele of FcγRIIIA (158V).

[0445] In some embodiments, the engineered antibodies of the invention are particularly effective in treating and/or preventing non-Hodgkin's lymphoma (NHL). The engineered antibodies of the invention are therapeutically more effective than current therapeutic regimens for NHL, including but not limited to chemotherapy, and immunotherapy using anti-CD20 mAb, Rituximab. The efficacy of anti-CD20 monoclonal antibodies however depends on the FcγR polymorphism of the subject (Carton et al., 2002 Blood, 99: 754-8; Weng et al., 2003 J Clin Oncol. 21(21):3940-7 both of which are incorporated herein by reference in their entireties). These receptors are expressed on the surface of the effector cells and mediate ADCC. High affinity alleles, of the low affinity activating receptors, improve the effector cells' ability to mediate ADCC. The methods of the invention allow engineering anti-CD20 antibodies harboring Fc mutations to enhance their affinity to FcγR on effector cells via their altered Fc domains. The engineered antibodies of the invention provide better immunotherapy reagents for patients regardless of their FcγR polymorphism.

[0446] An exemplary method for determining the efficacy of the engineered anti-CD20 antibodies in a subject may include the following: Plasmids harboring chimeric anti-HER2/neu heavy chain genes with Fc mutations that show substantially increased killing in ADCC can be be used as a backbone to transfer in the variable domain from the Rituximab heavy chain gene. The variable region from the anti-HER2/neu Fc variant is replaced with the variable region from Rituximab. Plasmids containing wild type Fc domains or a D265A mutation to abrogate FcR binding, or the anti-CD20 Fc variants are transiently cotransfected with the Rituximab light chain gene into 293H cells, conditioned media and the antibody is purified over a protein G column using routine methods.

[0447] Anti-CD20 mAbs harboring the Fc variants are tested by ADCC using a cultured B cell line to determine the ability of the Fc mutations to enhance ADCC. Standard ADCC is performed using methods disclosed herein. Lymphocytes are harvested from peripheral blood using a Ficoll-Paque gradient (Pharmacia). Target Daudi cells, a B-cell line expressing CD20, are loaded with Europium (PerkinElmer) and incubated with effectors for 4 hrs at 37° C. Released Europium is detected using a fluorescent plate reader (Wallac). The resulting ADCC data indicates the efficacy of the Fc variants to trigger NK cell mediated cytotoxicity and establish which anti-CD20 Fc variants can be tested with both patient samples and elutriated monocytes. Fc variants showing the greatest potential for enhancing the efficacy of the anti-CD20 antibody are then tested in an ADCC assay using PBMCs from patients. PBMC from healthy donors are used as effector cells. In vitro ADCC assays using anti-CD20 variants and Rituximab are performed in primary lymphoma cells from patients with follicular lymphoma. The specific FcγR polymorphism of the donors is determined and cataloged using methods known in the art. ADCC assay is performed by effector cells from patients with different FcγRIIIA and FcγRIIA genotypes.

[0448] According to an aspect of the invention, molecules (e.g., antibodies) of the invention comprising variant Fc regions enhance the efficacy of cancer immunotherapy by increasing the potency of the antibody effector function relative to a molecule containing the wild-type Fc region, e.g., ADCC, CDC, phagocytosis, opsonization, etc. In a specific embodiment, antibody dependent cellular toxicity and/or phagocytosis of tumor cells is enhanced using the molecules of the invention with variant Fc regions. Molecules of the invention may enhance the efficacy of immunotherapy cancer treatment by enhancing at least one antibody-mediated effector function. In one particular embodiment, a molecule of the invention comprising a variant Fc region enhances the efficacy of immunotherapy treatment by enhancing the complement dependent cascade. In another embodiment of the invention, the molecule of the invention comprising a variant Fc region enhances the efficacy of immunotherapy treatment by enhancing the phagocytosis and/or opsonization of the targeted tumor cells. In another embodiment of the invention, the molecule of the invention comprising a variant Fc region enhances the efficacy of treatment by enhancing antibody-dependent cell-mediated cytotoxicity (“ADCC”) in destruction of the targeted tumor cells.

[0449] The invention further contemplates engineering therapeutic antibodies (e.g., tumor specific monoclonal antibodies) for enhancing the therapeutic efficacy of the therapeutic antibody, for example, by enhancing the effector function of the therapeutic antibody (e.g., ADCC). Preferably the therapeutic antibody is a cytotoxic and/or opsonizing antibody. It will be appreciated by one of skill in the art, that once molecules of the invention with desired binding properties (e.g., molecules with variant Fc regions with at least one amino acid modification, which modification enhances the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA relative to a comparable molecule, comprising a wild-type Fc region) have been identified (See Section 5.2 and Table 8) according to the methods of the invention, therapeutic antibodies may be engineered using standard recombinant DNA techniques and any known mutagenesis techniques, as described in Section 5.2.2 to produce engineered therapeutic carrying the identified mutation sites with the desired binding properties. Any of the therapeutic antibodies listed in Table 9 that have demonstrated therapeutic utility in cancer treatment, may be engineered according to the methods of the invention, for example, by modifying the Fc region to have an enhanced affinity for FcγRIIIA and/or FcγRIIA compared to a therapeutic antibody having a wild-type Fc region, and used for the treatment and or prevention of a cancer characterized by a cancer antigen. Other therapeutic antibodies include those against pathogenic agents such as those against Streptococcus pneumoniae Serotype 6B, see, e.g., Sun et al., 1999, Infection and Immunity, 67(3): 1172-9.

[0450] The Fc variants of the invention may be incorporated into therapeutic antibodies such as those disclosed herein or other Fc fusion clinical candidates, i.e., a molecule comprising an Fc regions which has been approved for us in clinical trials or any other molecule that may benefit from the Fc variants of the instant invention, humanized, affinity matured, modified or engineered versions thereof.

[0451] The invention also encompasses engineering any other polypeptide comprising an Fc region which has therapeutic utility, including but not limited to ENBREL, according to the methods of the invention, in order to enhance the therapeutic efficacy of such polypeptides, for example, by enhancing the effector function of the polypeptide comprising an Fc region.

TABLE 9
THERAPEUTIC ANTIBODIES THAT CAN BE ENGINEERED
ACCORDING TO THE METHODS OF THE INVENTION
Company	Product	Disease	Target
Abgenix	ABX-EGF	Cancer	EGF receptor
AltaRex	OvaRex	ovarian cancer	tumor antigen CA125
	BravaRex	metastatic	tumor antigen MUC1
		cancers
Antisoma	Theragyn	ovarian cancer	PEM antigen
	(pemtumomabytrrium-
	90)
	Therex	breast cancer	PEM antigen
Boehringer	Blvatuzumab	head & neck	CD44
Ingelheim		cancer
Centocor/J&J	Panorex	Colorectal	17-1A
		cancer
	ReoPro	PTCA	gp IIIb/IIIa
	ReoPro	Acute MI	gp IIIb/IIIa
	ReoPro	Ischemic stroke	gp IIIb/IIIa
Corixa	Bexocar	NHL	CD20
CRC	MAb, idiotypic 105AD7	colorectal cancer	gp72
Technology		vaccine
Crucell	Anti-EpCAM	cancer	Ep-CAM
Cytoclonal	MAb, lung cancer	non-small cell	NA
		lung cancer
Genentech	Herceptin	metastatic breast	HER-2
		cancer
	Herceptin	early stage	HER-2
		breast cancer
	Rituxan	Relapsed/refractory	CD20
		low-grade or
		follicular NHL
	Rituxan	intermediate &	CD20
		high-grade NHL
	MAb-VEGF	NSCLC,	VEGF
		metastatic
	MAb-VEGF	Colorectal	VEGF
		cancer,
		metastatic
	AMD Fab	age-related	CD18
		macular
		degeneration
	E-26 (2nd gen. IgE)	allergic asthma	IgE
		& rhinitis
IDEC	Zevalin (Rituxan + yttrium-	low grade of	CD20
	90)	follicular,
		relapsed or
		refractory,
		CD20-positive,
		B-cell NHL and
		Rituximab-
		refractory NHL
ImClone	Cetuximab + innotecan	refractory	EGF receptor
		colorectal
		carcinoma
	Cetuximab + cisplatin &	newly diagnosed	EGF receptor
	radiation	or recurrent head
		& neck cancer
	Cetuximab + gemcitabine	newly diagnosed	EGF receptor
		metastatic
		pancreatic
		carcinoma
	Cetuximab + cisplatin + 5FU	recurrent or	EGF receptor
	or Taxol	metastatic head
		& neck cancer
	Cetuximab + carboplatin + paclitaxel	newly diagnosed	EGF receptor
		non-small cell
		lung carcinoma
	Cetuximab + cisplatin	head & neck	EGF receptor
		cancer
		(extensive
		incurable local-
		regional disease
		& distant
		metasteses)
	Cetuximab + radiation	locally advanced	EGF receptor
		head & neck
		carcinoma
	BEC2 + Bacillus	small cell lung	mimics ganglioside
	Calmette Guerin	carcinoma	GD3
	BEC2 + Bacillus	melanoma	mimics ganglioside
	Calmette Guerin		GD3
	IMC-1C11	colorectal cancer	VEGF-receptor
		with liver
		metasteses
ImmonoGen	nuC242-DM1	Colorectal,	nuC242
		gastric, and
		pancreatic
		cancer
ImmunoMedics	LymphoCide	Non-Hodgkins	CD22
		lymphoma
	LymphoCide Y-90	Non-Hodgkins	CD22
		lymphoma
	CEA-Cide	metastatic solid	CEA
		tumors
	CEA-Cide Y-90	metastatic solid	CEA
		tumors
	CEA-Scan (Tc-99m-	colorectal cancer	CEA
	labeled arcitumomab)	(radioimaging)
	CEA-Scan (Tc-99m-	Breast cancer	CEA
	labeled arcitumomab)	(radioimaging)
	CEA-Scan (Tc-99m-	lung cancer	CEA
	labeled arcitumomab)	(radioimaging)
	CEA-Scan (Tc-99m-	intraoperative	CEA
	labeled arcitumomab)	tumors (radioimaging)
	LeukoScan (Tc-99m-	soft tissue	CEA
	labeled sulesomab)	infection
		(radioimaging)
	LymphoScan (Tc-99m-	lymphomas	CD22
	labeled)	(radioimaging)
	AFP-Scan (Tc-99m-	liver 7 gem-cell	AFP
	labeled)	cancers
		(radioimaging)
Intracel	HumaRAD-HN (+yttrium-	head & neck	NA
	90)	cancer
	HumaSPECT	colorectal	NA
		imaging
Medarex	MDX-101 (CTLA-4)	Prostate and	CTLA-4
		other cancers
	MDX-210 (her-2	Prostate cancer	HER-2
	overexpression)
	MDX-210/MAK	Cancer	HER-2
MedImmune	Vitaxin	Cancer	αvβ3
Merck KGaA	MAb 425	Various cancers	EGF receptor
	IS-IL-2	Various cancers	Ep-CAM
Millennium	Campath	chronic	CD52
	(alemtuzumab)	lymphocytic
		leukemia
NeoRx	CD20-streptavidin (+biotin-	Non-Hodgkins	CD20
	yttrium 90)	lymphoma
	Avidicin (albumin + NRLU13)	metastatic	NA
		cancer
Peregrine	Oncolym (+iodine-131)	Non-Hodgkins	HLA-DR 10 beta
		lymphoma
	Cotara (+iodine-131)	unresectable	DNA-associated
		malignant	proteins
		glioma
Pharmacia	C215 (+staphylococcal	pancreatic	NA
Corporation	enterotoxin)	cancer
	MAb, lung/kidney	lung & kidney	NA
	cancer	cancer
	nacolomab tafenatox	colon &	NA
	(C242 + staphylococcal	pancreatic
	enterotoxin)	cancer
Protein Design	Nuvion	T cell	CD3
Labs		malignancies
	SMART M195	AML	CD33
	SMART 1D10	NHL	HLA-DR antigen
Titan	CEAVac	colorectal	CEA
		cancer,
		advanced
	TriGem	metastatic	GD2-ganglioside
		melanoma &
		small cell lung
		cancer
	TriAb	metastatic breast	MUC-1
		cancer
Trilex	CEAVac	colorectal	CEA
		cancer,
		advanced
	TriGem	metastatic	GD2-ganglioside
		melanoma &
		small cell lung
		cancer
	TriAb	metastatic breast	MUC-1
		cancer
Viventia	NovoMAb-G2	Non-Hodgkins	NA
Biotech	radiolabeled	lymphoma
	Monopharm C	colorectal &	SK-1 antigen
		pancreatic
		carcinoma
	GlioMAb-H (+gelonin	gliorna,	NA
	toxin)	melanoma &
		neuroblastoma
Xoma	Rituxan	Relapsed/refractory	CD20
		low-grade or
		follicular NHL
	Rituxan	intermediate &	CD20
		high-grade NHL
	ING-1	adenomcarcinoma	Ep-CAM

[0452] Accordingly, the invention provides methods of preventing or treating cancer characterized by a cancer antigen, using a therapeutic antibody that binds a cancer antigen and is cytotoxic and has been modified at one or more sites in the Fc region, according to the invention, to bind FcγRIIIA and/or FcγRIIA with a higher affinity than the parent therapeutic antibody, and/or mediates effector function (e.g., ADCC, phagocytosis) more effectively. In another embodiment, the invention provides methods of preventing or treating cancer characterized by a cancer antigen, using a therapeutic antibody that binds a cancer antigen and is cytotoxic, and has been engineered according to the invention to bind FcγRIIIA and/or FcγRIIA with a higher affinity and bind FcγRIIB with a lower affinity than the parent therapeutic antibody, and/or mediates effector function (e.g., ADCC, phagocytosis) more effectively. The therapeutic antibodies that have been engineered according to the invention are useful for prevention or treatment of cancer, since they have an enhanced cytotoxic activity (e.g., enhanced tumor cell killing and/or enhanced for example, ADCC activity or CDC activity).

[0453] Cancers associated with a cancer antigen may be treated or prevented by administration of a therapeutic antibody that binds a cancer antigen and is cytotoxic, and has been engineered according to the methods of the invention to have, for example, an enhanced effector function. In one particular embodiment, the therapeutic antibodies engineered according to the methods of the invention enhance the antibody-mediated cytotoxic effect of the antibody directed at the particular cancer antigen. For example, but not by way of limitation, cancers associated with the following cancer antigens may be treated or prevented by the methods and compositions of the invention: KS ¼ pan-carcinoma antigen (Perez and Walker, 1990, J. Immunol. 142:32-37; Bumal, 1988, Hybridoma 7(4):407-415), ovarian carcinoma antigen (CA125) (Yu et al., 1991, Cancer Res. 51 (2):48-475), prostatic acid phosphate (Tailor et al., 1990, Nucl. Acids Res. 18(1):4928), prostate specific antigen (Henttu and Vihko, 1989, Biochem. Biophys. Res. Comm. 10(2):903-910; Israeli et al., 1993, Cancer Res. 53:227-230), melanoma-associated antigen p97 (Estin et al., 1989, J. Natl. Cancer Instit. 81(6):445-44), melanoma antigen gp75 (Vijayasardahl et al., 1990, J. Exp. Med. 171(4):1375-1380), high molecular weight melanoma antigen (HMW-MAA) (Natali et al., 1987, Cancer 59:55-3; Mittelman et al., 1990, J. Clin. Invest. 86:2136-2144)), prostate specific membrane antigen, carcinoembryonic antigen (CEA) (Foon et al., 1994, Proc. Am. Soc. Clin. Oncol. 13:294), polymorphic epithelial mucin antigen, human milk fat globule antigen, Colorectal tumor-associated antigens such as: CEA, TAG-72 (Yokata et al., 1992, Cancer Res. 52:3402-3408), CO17-1A (Ragnhammar et al., 1993, Int. J. Cancer 53:751-758); GICA 19-9 (Herlyn et al., 1982, J. Clin. Immunol. 2:135), CTA-1 and LEA, Burkitt's lymphoma antigen-38.13, CD19 (Ghetie et al., 1994, Blood 83:1329-1336), human B-lymphoma antigen-CD20 (Reff et al., 1994, Blood 83:435-445), CD33 (Sgouros et al., 1993, J Nucl. Med. 34:422-430), melanoma specific antigens such as ganglioside GD2 (Saleh et al., 1993, J. Immunol., 151, 3390-3398), ganglioside GD3 (Shitara et al., 1993, Cancer Immunol. Immunother. 36:373-380), ganglioside GM2 (Livingston et al., 1994, J. Clin. Oncol. 12:1036-1044), ganglioside GM3 (Hoon et al., 1993, Cancer Res. 53:5244-5250), tumor-specific transplantation type of cell-surface antigen (TSTA) such as virally-induced tumor antigens including T-antigen DNA tumor viruses and envelope antigens of RNA tumor viruses, oncofetal antigen-alpha-fetoprotein such as CEA of colon, bladder tumor oncofetal antigen (Hellstrom et al., 1985, Cancer. Res. 45:2210-2188), differentiation antigen such as human lung carcinoma antigen L6, L20 (Hellstrom et al., 1986, Cancer Res. 46:3917-3923), antigens of fibrosarcoma, human leukemia T cell antigen-Gp37 (Bhattacharya-Chatterjee et al., 1988, J. of Immun. 141:1398-1403), neoglycoprotein, sphingolipids, breast cancer antigen such as EGFR (Epidermal growth factor receptor), HER2 antigen (P185^HER2), polymorphic epithelial mucin (PEM) (Hilkens et al., 1992, Trends in Bio. Chem. Sci. 17:359), malignant human lymphocyte antigen-APO-1 (Bernhard et al., 1989, Science 245:301-304), differentiation antigen (Feizi, 1985, Nature 314:53-57) such as I antigen found in fetal erthrocytes and primary endoderm, I(Ma) found in gastric adencarcinomas, M18 and M39 found in breast epithelium, SSEA-1 found in myeloid cells, VEP8, VEP9, Myl, VIM-D5, and D₁56-22 found in colorectal cancer, TRA-1-85 (blood group H), C14 found in colonic adenocarcinoma, F3 found in lung adenocarcinoma, AH6 found in gastric cancer, Y hapten, Le^y found in embryonal carcinoma cells, TL5 (blood group A), EGF receptor found in A431 cells, E₁ series (blood group B) found in pancreatic cancer, FC10.2 found in embryonal carcinoma cells, gastric adenocarcinoma, CO-514 (blood group Le^a) found in adenocarcinoma, NS-10 found in adenocarcinomas, CO-43 (blood group Le^b), G49, EGF receptor, (blood group ALe^b/Le^y) found in colonic adenocarcinoma, 19.9 found in colon cancer, gastric cancer mucins, T₅A₇ found in myeloid cells, R₂₄ found in melanoma, 4.2, GD3, D1.1, OFA-1, G_M2, OFA-2, G_D2, M1:22:25:8 found in embryonal carcinoma cells and SSEA-3, SSEA-4 found in 4-8-cell stage embryos. In another embodiment, the antigen is a T cell receptor derived peptide from a cutaneous T cell lymphoma (see Edelson, 1998, The Cancer Journal 4:62).

[0454] Cancers and related disorders that can be treated or prevented by methods and compositions of the present invention include, but are not limited to, the following: Leukemias including, but not limited to, acute leukemia, acute lymphocytic leukemia, acute myelocytic leukemias such as myeloblastic, promyelocytic, myelomonocytic, monocytic, erythroleukemia leukemias and myelodysplastic syndrome, chronic leukemias such as but not limited to, chronic myelocytic (granulocytic) leukemia, chronic lymphocytic leukemia, hairy cell leukemia; polycythemia vera; lymphomas such as but not limited to Hodgkin's disease, non-Hodgkin's disease; multiple myelomas such as but not limited to smoldering multiple myeloma, nonsecretory myeloma, osteosclerotic myeloma, plasma cell leukemia, solitary plasmacytoma and extramedullary plasmacytoma; Waldenström's macroglobulinemia; monoclonal gammopathy of undetermined significance; benign monoclonal gammopathy; heavy chain disease; bone and connective tissue sarcomas such as but not limited to bone sarcoma, osteosarcoma, chondrosarcoma, Ewing's sarcoma, malignant giant cell tumor, fibrosarcoma of bone, chordoma, periosteal sarcoma, soft-tissue sarcomas, angiosarcoma (hemangiosarcoma), fibrosarcoma, Kaposi's sarcoma, leiomyosarcoma, liposarcoma, lymphangiosarcoma, neurilemmoma, rhabdomyosarcoma, synovial sarcoma; brain tumors including but not limited to, glioma, astrocytoma, brain stem glioma, ependymoma, oligodendroglioma, nonglial tumor, acoustic neurinoma, craniopharyngioma, medulloblastoma, meningioma, pineocytoma, pineoblastoma, primary brain lymphoma; breast cancer including, but not limited to, adenocarcinoma, lobular (small cell) carcinoma, intraductal carcinoma, medullary breast cancer, mucinous breast cancer, tubular breast cancer, papillary breast cancer, Paget's disease, and inflammatory breast cancer; adrenal cancer, including but not limited to, pheochromocytom and adrenocortical carcinoma; thyroid cancer such as but not limited to papillary or follicular thyroid cancer, medullary thyroid cancer and anaplastic thyroid cancer; pancreatic cancer, including but not limited to, insulinoma, gastrinoma, glucagonoma, vipoma, somatostatin-secreting tumor, and carcinoid or islet cell tumor; pituitary cancers including but not limited to, Cushing's disease, prolactin-secreting tumor, acromegaly, and diabetes insipius; eye cancers including but not limited to, ocular melanoma such as iris melanoma, choroidal melanoma, and cilliary body melanoma, and retinoblastoma; vaginal cancers, including but not limited to, squamous cell carcinoma, adenocarcinoma, and melanoma; vulvar cancer, including but not limited to, squamous cell carcinoma, melanoma, adenocarcinoma, basal cell carcinoma, sarcoma, and Paget's disease; cervical cancers including but not limited to, squamous cell carcinoma, and adenocarcinoma; uterine cancers including but not limited to, endometrial carcinoma and uterine sarcoma; ovarian cancers including but not limited to, ovarian epithelial carcinoma, borderline tumor, germ cell tumor, and stromal tumor; esophageal cancers including but not limited to, squamous cancer, adenocarcinoma, adenoid cyctic carcinoma, mucoepidermoid carcinoma, adenosquamous carcinoma, sarcoma, melanoma, plasmacytoma, verrucous carcinoma, and oat cell (small cell) carcinoma; stomach cancers including but not limited to, adenocarcinoma, fungating (polypoid), ulcerating, superficial spreading, diffusely spreading, malignant lymphoma, liposarcoma, fibrosarcoma, and carcinosarcoma; colon cancers; rectal cancers; liver cancers including but not limited to hepatocellular carcinoma and hepatoblastoma, gallbladder cancers including but not limited to, adenocarcinoma; cholangiocarcinomas including but not limited to, pappillary, nodular, and diffuse; lung cancers including but not limited to, non-small cell lung cancer, squamous cell carcinoma (epidermoid carcinoma), adenocarcinoma, large-cell carcinoma and small-cell lung cancer; testicular cancers including but not limited to, germinal tumor, seminoma, anaplastic, classic (typical), spermatocytic, nonseminoma, embryonal carcinoma, teratoma carcinoma, choriocarcinoma (yolk-sac tumor), prostate cancers including but not limited to, adenocarcinoma, leiomyosarcoma, and rhabdomyosarcoma; penal cancers; oral cancers including but not limited to, squamous cell carcinoma; basal cancers; salivary gland cancers including but not limited to, adenocarcinoma, mucoepidermoid carcinoma, and adenoidcystic carcinoma; pharynx cancers including but not limited to, squamous cell cancer, and verrucous; skin cancers including but not limited to, basal cell carcinoma, squamous cell carcinoma and melanoma, superficial spreading melanoma, nodular melanoma, lentigo malignant melanoma, acral lentiginous melanoma; kidney cancers including but not limited to, renal cell cancer, adenocarcinoma, hypernephroma, fibrosarcoma, transitional cell cancer (renal pelvis and/or uterer); Wilms' tumor; bladder cancers including but not limited to, transitional cell carcinoma, squamous cell cancer, adenocarcinoma, carcinosarcoma. In addition, cancers include myxosarcoma, osteogenic sarcoma, endotheliosarcoma, lymphangioendotheliosarcoma, mesothelioma, synovioma, hemangioblastoma, epithelial carcinoma, cystadenocarcinoma, bronchogenic carcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillary carcinoma and papillary adenocarcinomas (for a review of such disorders, see Fishman et al., 1985, Medicine, 2d Ed., J.B. Lippincott Co., Philadelphia and Murphy et al., 1997, Informed Decisions: The Complete Book of Cancer Diagnosis, Treatment, and Recovery, Viking Penguin, Penguin Books U.S.A., Inc., United States of America).

[0455] Accordingly, the methods and compositions of the invention are also useful in the treatment or prevention of a variety of cancers or other abnormal proliferative diseases, including (but not limited to) the following: carcinoma, including that of the bladder, breast, colon, kidney, liver, lung, ovary, pancreas, stomach, prostate, cervix, thyroid and skin; including squamous cell carcinoma; hematopoietic tumors of lymphoid lineage, including leukemia, acute lymphocytic leukemia, acute lymphoblastic leukemia, B-cell lymphoma, T-cell lymphoma, Burketts lymphoma; hematopoietic tumors of myeloid lineage, including acute and chronic myelogenous leukemias and promyelocytic leukemia; tumors of mesenchymal origin, including fibrosarcoma and rhabdomyoscarcoma; other tumors, including melanoma, seminoma, tetratocarcinoma, neuroblastoma and glioma; tumors of the central and peripheral nervous system, including astrocytoma, neuroblastoma, glioma, and schwannomas; tumors of mesenchymal origin, including fibrosarcoma, rhabdomyoscarama, and osteosarcoma; and other tumors, including melanoma, xenoderma pegmentosum, keratoactanthoma, seminoma, thyroid follicular cancer and teratocarcinoma. It is also contemplated that cancers caused by aberrations in apoptosis would also be treated by the methods and compositions of the invention. Such cancers may include but not be limited to follicular lymphomas, carcinomas with p53 mutations, hormone dependent tumors of the breast, prostate and ovary, and precancerous lesions such as familial adenomatous polyposis, and myelodysplastic syndromes. In specific embodiments, malignancy or dysproliferative changes (such as metaplasias and dysplasias), or hyperproliferative disorders, are treated or prevented by the methods and compositions of the invention in the ovary, bladder, breast, colon, lung, skin, pancreas, or uterus. In other specific embodiments, sarcoma, melanoma, or leukemia is treated or prevented by the methods and compositions of the invention.

[0456] In a specific embodiment, a molecule of the invention (e.g., an antibody comprising a variant Fc region, or a therapeutic monoclonal antibody engineered according to the methods of the invention) inhibits or reduces the growth of primary tumor or metastasis of cancerous cells by at least 99%, at least 95%, at least 90%, at least 85%, at least 80%, at least 75%, at least 70%, at least 60%, at least 50%, at least 45%, at least 40%, at least 45%, at least 35%, at least 30%, at least 25%, at least 20%, or at least 10% relative to the growth of primary tumor or metastasis in the absence of said molecule of the invention.

[0457] 5.4.1.1 Combination Therapy

[0458] The invention further encompasses administering the molecules of the invention in combination with other therapies known to those skilled in the art for the treatment or prevention of cancer, including but not limited to, current standard and experimental chemotherapies, hormonal therapies, biological therapies, immunotherapies, radiation therapies, or surgery. In some embodiments, the molecules of the invention may be administered in combination with a therapeutically or prophylactically effective amount of one or more anti-cancer agents, therapeutic antibodies (e.g., antibodies listed in Table 9), or other agents known to those skilled in the art for the treatment and/or prevention of cancer (See Section 5.4.1.2).

[0459] In certain embodiments, one or more molecule of the invention is administered to a mammal, preferably a human, concurrently with one or more other therapeutic agents useful for the treatment of cancer. The term “concurrently” is not limited to the administration of prophylactic or therapeutic agents at exactly the same time, but rather it is meant that a molecule of the invention and the other agent are administered to a mammal in a sequence and within a time interval such that the molecule of the invention can act together with the other agent to provide an increased benefit than if they were administered otherwise. For example, each prophylactic or therapeutic agent (e.g., chemotherapy, radiation therapy, hormonal therapy or biological therapy) may be administered at the same time or sequentially in any order at different points in time; however, if not administered at the same time, they should be administered sufficiently close in time so as to provide the desired therapeutic or prophylactic effect. Each therapeutic agent can be administered separately, in any appropriate form and by any suitable route. In various embodiments, the prophylactic or therapeutic agents are administered less than 1 hour apart, at about 1 hour apart, at about 1 hour to about 2 hours apart, at about 2 hours to about 3 hours apart, at about 3 hours to about 4 hours apart, at about 4 hours to about 5 hours apart, at about 5 hours to about 6 hours apart, at about 6 hours to about 7 hours apart, at about 7 hours to about 8 hours apart, at about 8 hours to about 9 hours apart, at about 9 hours to about 10 hours apart, at about 10 hours to about 11 hours apart, at about 11 hours to about 12 hours apart, no more than 24 hours apart or no more than 48 hours apart. In preferred embodiments, two or more components are administered within the same patient visit.

[0460] In other embodiments, the prophylactic or therapeutic agents are administered at about 2 to 4 days apart, at about 4 to 6 days apart, at about 1 week part, at about 1 to 2 weeks apart, or more than 2 weeks apart. In preferred embodiments, the prophylactic or therapeutic agents are administered in a time frame where both agents are still active. One skilled in the art would be able to determine such a time frame by determining the half life of the administered agents.

[0461] In certain embodiments, the prophylactic or therapeutic agents of the invention are cyclically administered to a subject. Cycling therapy involves the administration of a first agent for a period of time, followed by the administration of a second agent and/or third agent for a period of time and repeating this sequential administration. Cycling therapy can reduce the development of resistance to one or more of the therapies, avoid or reduce the side effects of one of the therapies, and/or improves the efficacy of the treatment.

[0462] In certain embodiments, prophylactic or therapeutic agents are administered in a cycle of less than about 3 weeks, about once every two weeks, about once every 10 days or about once every week. One cycle can comprise the administration of a therapeutic or prophylactic agent by infusion over about 90 minutes every cycle, about 1 hour every cycle, about 45 minutes every cycle. Each cycle can comprise at least 1 week of rest, at least 2 weeks of rest, at least 3 weeks of rest. The number of cycles administered is from about 1 to about 12 cycles, more typically from about 2 to about 10 cycles, and more typically from about 2 to about 8 cycles.

[0463] In yet other embodiments, the therapeutic and prophylactic agents of the invention are administered in metronomic dosing regimens, either by continuous infusion or frequent administration without extended rest periods. Such metronomic administration can involve dosing at constant intervals without rest periods. Typically the therapeutic agents, in particular cytotoxic agents, are used at lower doses. Such dosing regimens encompass the chronic daily administration of relatively low doses for extended periods of time. In preferred embodiments, the use of lower doses can minimize toxic side effects and eliminate rest periods. In certain embodiments, the therapeutic and prophylactic agents are delivered by chronic low-dose or continuous infusion ranging from about 24 hours to about 2 days, to about 1 week, to about 2 weeks, to about 3 weeks to about 1 month to about 2 months, to about 3 months, to about 4 months, to about 5 months, to about 6 months. The scheduling of such dose regimens can be optimized by the skilled oncologist.

[0464] In other embodiments, courses of treatment are administered concurrently to a mammal, i.e., individual doses of the therapeutics are administered separately yet within a time interval such that molecules of the invention can work together with the other agent or agents. For example, one component may be administered one time per week in combination with the other components that may be administered one time every two weeks or one time every three weeks. In other words, the dosing regimens for the therapeutics are carried out concurrently even if the therapeutics are not administered simultaneously or within the same patient visit.

[0465] When used in combination with other prophylactic and/or therapeutic agents, the molecules of the invention and the prophylactic and/or therapeutic agent can act additively or, more preferably, synergistically. In one embodiment, a molecule of the invention is administered concurrently with one or more therapeutic agents in the same pharmaceutical composition. In another embodiment, a molecule of the invention is administered concurrently with one or more other therapeutic agents in separate pharmaceutical compositions. In still another embodiment, a molecule of the invention is administered prior to or subsequent to administration of another prophylactic or therapeutic agent. The invention contemplates administration of a molecule of the invention in combination with other prophylactic or therapeutic agents by the same or different routes of administration, e.g., oral and parenteral. In certain embodiments, when a molecule of the invention is administered concurrently with another prophylactic or therapeutic agent that potentially produces adverse side effects including, but not limited to, toxicity, the prophylactic or therapeutic agent can advantageously be administered at a dose that falls below the threshold that the adverse side effect is elicited.

[0466] The dosage amounts and frequencies of administration provided herein are encompassed by the terms therapeutically effective and prophylactically effective. The dosage and frequency further will typically vary according to factors specific for each patient depending on the specific therapeutic or prophylactic agents administered, the severity and type of cancer, the route of administration, as well as age, body weight, response, and the past medical history of the patient. Suitable regimens can be selected by one skilled in the art by considering such factors and by following, for example, dosages reported in the literature and recommended in the Physician's Desk Reference (56^th ed., 2002).

[0467] 5.4.1.2 Other Therapeutic/Prophylactic Agents

[0468] In a specific embodiment, the methods of the invention encompass the administration of one or more molecules of the invention with one or more therapeutic agents used for the treatment and/or prevention of cancer. In one embodiment, angiogenesis inhibitors may be administered in combination with the molecules of the invention. Angiogenesis inhibitors that can be used in the methods and compositions of the invention include but are not limited to: Angiostatin (plasminogen fragment); antiangiogenic antithrombin III; Angiozyme; ABT-627; Bay 12-9566; Benefin; Bevacizumab; BMS-275291; cartilage-derived inhibitor (CDI); CAI; CD59 complement fragment; CEP-7055; Col 3; Combretastatin A-4; Endostatin (collagen XVIII fragment); Fibronectin fragment; Gro-beta; Halofuginone; Heparinases; Heparin hexasaccharide fragment; HMV833; Human chorionic gonadotropin (hCG); IM-862; Interferon alpha/beta/gamma; Interferon inducible protein (IP-10); Interleukin-12; Kringle 5 (plasminogen fragment); Marimastat; Metalloproteinase inhibitors (TIMPs); 2-Methoxyestradiol; MMI 270 (CGS 27023A); MoAb IMC-1C11; Neovastat; NM-3; Panzem; PI-88; Placental ribonuclease inhibitor; Plasminogen activator inhibitor; Platelet factor-4 (PF4); Prinomastat; Prolactin 16 kD fragment; Proliferin-related protein (PRP); PTK 787/ZK 222594; Retinoids; Solimastat; Squalamine; SS 3304; SU 5416; SU6668; SU11248; Tetrahydrocortisol-S; tetrathiomolybdate; thalidomide; Thrombospondin-1 (TSP-1); TNP-470; Transforming growth factor-beta (TGF-b); Vasculostatin; Vasostatin (calreticulin fragment); ZD6126; ZD 6474; farnesyl transferase inhibitors (FTI); and bisphosphonates.

[0469] Anti-cancer agents that can be used in combination with the molecules of the invention in the various embodiments of the invention, including pharmaceutical compositions and dosage forms and kits of the invention, include, but are not limited to: acivicin; aclarubicin; acodazole hydrochloride; acronine; adozelesin; aldesleukin; altretamine; ambomycin; ametantrone acetate; aminoglutethimide; amsacrine; anastrozole; anthramycin; asparaginase; asperlin; azacitidine; azetepa; azotomycin; batimastat; benzodepa; bicalutamide; bisantrene hydrochloride; bisnafide dimesylate; bizelesin; bleomycin sulfate; brequinar sodium; bropirimine; busulfan; cactinomycin; calusterone; caracemide; carbetimer; carboplatin; carmustine; carubicin hydrochloride; carzelesin; cedefingol; chlorambucil; cirolemycin; cisplatin; cladribine; crisnatol mesylate; cyclophosphamide; cytarabine; dacarbazine; dactinomycin; daunorubicin hydrochloride; decitabine; dexormaplatin; dezaguanine; dezaguanine mesylate; diaziquone; docetaxel; doxorubicin; doxorubicin hydrochloride; droloxifene; droloxifene citrate; dromostanolone propionate; duazomycin; edatrexate; eflornithine hydrochloride; elsamitrucin; enloplatin; enpromate; epipropidine; epirubicin hydrochloride; erbulozole; esorubicin hydrochloride; estramustine; estramustine phosphate sodium; etanidazole; etoposide; etoposide phosphate; etoprine; fadrozole hydrochloride; fazarabine; fenretinide; floxuridine; fludarabine phosphate; fluorouracil; flurocitabine; fosquidone; fostriecin sodium; gemcitabine; gemcitabine hydrochloride; hydroxyurea; idarubicin hydrochloride; ifosfamide; ilmofosine; interleukin II (including recombinant interleukin II, or rIL2), interferon alfa-2a; interferon alfa-2b; interferon alfa-n1; interferon alfa-n3; interferon beta-I a; interferon gamma-I b; iproplatin; irinotecan hydrochloride; lanreotide acetate; letrozole; leuprolide acetate; liarozole hydrochloride; lometrexol sodium; lomustine; losoxantrone hydrochloride; masoprocol; maytansine; mechlorethamine hydrochloride; megestrol acetate; melengestrol acetate; melphalan; menogaril; mercaptopurine; methotrexate; methotrexate sodium; metoprine; meturedepa; mitindomide; mitocarcin; mitocromin; mitogillin; mitomalcin; mitomycin; mitosper; mitotane; mitoxantrone hydrochloride; mycophenolic acid; nocodazole; nogalamycin; ormaplatin; oxisuran; paclitaxel; pegaspargase; peliomycin; pentamustine; peplomycin sulfate; perfosfamide; pipobroman; piposulfan; piroxantrone hydrochloride; plicamycin; plomestane; porfimer sodium; porfiromycin; prednimustine; procarbazine hydrochloride; puromycin; puromycin hydrochloride; pyrazofurin; riboprine; rogletimide; safingol; safingol hydrochloride; semustine; simtrazene; sparfosate sodium; sparsomycin; spirogermanium hydrochloride; spiromustine; spiroplatin; streptonigrin; streptozocin; sulofenur; talisomycin; tecogalan sodium; tegafur; teloxantrone hydrochloride; temoporfin; teniposide; teroxirone; testolactone; thiamiprine; thioguanine; thiotepa; tiazofurin; tirapazamine; toremifene citrate; trestolone acetate; triciribine phosphate; trimetrexate; trimetrexate glucuronate; triptorelin; tubulozole hydrochloride; uracil mustard; uredepa; vapreotide; verteporfin; vinblastine sulfate; vincristine sulfate; vindesine; vindesine sulfate; vinepidine sulfate; vinglycinate sulfate; vinleurosine sulfate; vinorelbine tartrate; vinrosidine sulfate; vinzolidine sulfate; vorozole; zeniplatin; zinostatin; zorubicin hydrochloride. Other anti-cancer drugs include, but are not limited to: 20-epi-1,25 dihydroxyvitamin D3; 5-ethynyluracil; abiraterone; aclarubicin; acylfulvene; adecypenol; adozelesin; aldesleukin; ALL-TK antagonists; altretamine; ambamustine; amidox; amifostine; aminolevulinic acid; amrubicin; amsacrine; anagrelide; anastrozole; andrographolide; angiogenesis inhibitors; antagonist D; antagonist G; antarelix; anti-dorsalizing morphogenetic protein-1; antiandrogen, prostatic carcinoma; antiestrogen; antineoplaston; antisense oligonucleotides; aphidicolin glycinate; apoptosis gene modulators; apoptosis regulators; apurinic acid; ara-CDP-DL-PTBA; arginine deaminase; asulacrine; atamestane; atrimustine; axinastatin 1; axinastatin 2; axinastatin 3; azasetron; azatoxin; azatyrosine; baccatin III derivatives; balanol; batimastat; BCR/ABL antagonists; benzochlorins; benzoylstaurosporine; beta lactam derivatives; beta-alethine; betaclamycin B; betulinic acid; bFGF inhibitor; bicalutamide; bisantrene; bisaziridinylspermine; bisnafide; bistratene A; bizelesin; breflate; bropirimine; budotitane; buthionine sulfoximine; calcipotriol; calphostin C; camptothecin derivatives; canarypox IL-2; capecitabine; carboxamide-amino-triazole; carboxyamidotriazole; CaRest M3; CARN 700; cartilage derived inhibitor; carzelesin; casein kinase inhibitors (ICOS); castanospermine; cecropin B; cetrorelix; chlorins; chloroquinoxaline sulfonamide; cicaprost; cis-porphyrin; cladribine; clomifene analogues; clotrimazole; collismycin A; collismycin B; combretastatin A4; combretastatin analogue; conagenin; crambescidin 816; crisnatol; cryptophycin 8; cryptophycin A derivatives; curacin A; cyclopentanthraquinones; cycloplatam; cypemycin; cytarabine ocfosfate; cytolytic factor; cytostatin; dacliximab; decitabine; dehydrodidemnin B; deslorelin; dexamethasone; dexifosfamide; dexrazoxane; dexverapamil; diaziquone; didemnin B; didox; diethylnorspermine; dihydro-5-azacytidine; dihydrotaxol, 9-; dioxamycin; diphenyl spiromustine; docetaxel; docosanol; dolasetron; doxifluridine; droloxifene; dronabinol; duocarmycin SA; ebselen; ecomustine; edelfosine; edrecolomab; eflornithine; elemene; emitefur; epirubicin; epristeride; estramustine analogue; estrogen agonists; estrogen antagonists; etanidazole; etoposide phosphate; exemestane; fadrozole; fazarabine; fenretinide; filgrastim; finasteride; flavopiridol; flezelastine; fluasterone; fludarabine; fluorodaunorunicin hydrochloride; forfenimex; formestane; fostriecin; fotemustine; gadolinium texaphyrin; gallium nitrate; galocitabine; ganirelix; gelatinase inhibitors; gemcitabine; glutathione inhibitors; hepsulfam; heregulin; hexamethylene bisacetamide; hypericin; ibandronic acid; idarubicin; idoxifene; idramantone; ilmofosine; ilomastat; imidazoacridones; imiquimod; immunostimulant peptides; insulin-like growth factor-1 receptor inhibitor; interferon agonists; interferons; interleukins; iobenguane; iododoxorubicin; ipomeanol, 4-; iroplact; irsogladine; isobengazole; isohomohalicondrin B; itasetron; jasplakinolide; kahalalide F; lamellarin-N triacetate; lanreotide; leinamycin; lenograstim; lentinan sulfate; leptolstatin; letrozole; leukemia inhibiting factor; leukocyte alpha interferon; leuprolide+estrogen+progesterone; leuprorelin; levamisole; liarozole; linear polyamine analogue; lipophilic disaccharide peptide; lipophilic platinum compounds; lissoclinamide 7; lobaplatin; lombricine; lometrexol; lonidamine; losoxantrone; lovastatin; loxoribine; lurtotecan; lutetium texaphyrin; lysofylline; lytic peptides; maitansine; mannostatin A; marimastat; masoprocol; maspin; matrilysin inhibitors; matrix metalloproteinase inhibitors; menogaril; merbarone; meterelin; methioninase; metoclopramide; MIF inhibitor; mifepristone; miltefosine; mirimostim; mismatched double stranded RNA; mitoguazone; mitolactol; mitomycin analogues; mitonafide; mitotoxin fibroblast growth factor-saporin; mitoxantrone; mofarotene; molgramostim; monoclonal antibody, human chorionic gonadotrophin; monophosphoryl lipid A+myobacterium cell wall sk; mopidamol; multiple drug resistance gene inhibitor; multiple tumor suppressor 1-based therapy; mustard anticancer agent; mycaperoxide B; mycobacterial cell wall extract; myriaporone; N-acetyldinaline; N-substituted benzamides; nafarelin; nagrestip; naloxone+pentazocine; napavin; naphterpin; nartograstim; nedaplatin; nemorubicin; neridronic acid; neutral endopeptidase; nilutamide; nisamycin; nitric oxide modulators; nitroxide antioxidant; nitrullyn; O6-benzylguanine; octreotide; okicenone; oligonucleotides; onapristone; ondansetron; ondansetron; oracin; oral cytokine inducer; ormaplatin; osaterone; oxaliplatin; oxaunomycin; paclitaxel; paclitaxel analogues; paclitaxel derivatives; palauamine; palmitoylrhizoxin; pamidronic acid; panaxytriol; panomifene; parabactin; pazelliptine; pegaspargase; peldesine; pentosan polysulfate sodium; pentostatin; pentrozole; perflubron; perfosfamide; perillyl alcohol; phenazinomycin; phenylacetate; phosphatase inhibitors; picibanil; pilocarpine hydrochloride; pirarubicin; piritrexim; placetin A; placetin B; plasminogen activator inhibitor; platinum complex; platinum compounds; platinum-triamine complex; porfimer sodium; porfiromycin; prednisone; propyl bis-acridone; prostaglandin J2; proteasome inhibitors; protein A-based immune modulator; protein kinase C inhibitor; protein kinase C inhibitors, microalgal; protein tyrosine phosphatase inhibitors; purine nucleoside phosphorylase inhibitors; purpurins; pyrazoloacridine; pyridoxylated hemoglobin polyoxyethylene conjugate; raf antagonists; raltitrexed; ramosetron; ras farnesyl protein transferase inhibitors; ras inhibitors; ras-GAP inhibitor; retelliptine demethylated; rhenium Re 186 etidronate; rhizoxin; ribozymes; RII retinamide; rogletimide; rohitukine; romurtide; roquinimex; rubiginone B1; ruboxyl; safingol; saintopin; SarCNU; sarcophytol A; sargramostim; Sdi 1 mimetics; semustine; senescence derived inhibitor 1; sense oligonucleotides; signal transduction inhibitors; signal transduction modulators; single chain antigen binding protein; sizofuran; sobuzoxane; sodium borocaptate; sodium phenylacetate; solverol; somatomedin binding protein; sonermin; sparfosic acid; spicamycin D; spiromustine; splenopentin; spongistatin 1; squalamine; stem cell inhibitor; stem-cell division inhibitors; stipiamide; stromelysin inhibitors; sulfinosine; superactive vasoactive intestinal peptide antagonist; suradista; suramin; swainsonine; synthetic glycosaminoglycans; tallimustine; tamoxifen methiodide; tauromustine; tazarotene; tecogalan sodium; tegafur; tellurapyrylium; telomerase inhibitors; temoporfin; temozolomide; teniposide; tetrachlorodecaoxide; tetrazomine; thaliblastine; thiocoraline; thrombopoietin; thrombopoietin mimetic; thymalfasin; thymopoietin receptor agonist; thymotrinan; thyroid stimulating hormone; tin ethyl etiopurpurin; tirapazamine; titanocene bichloride; topsentin; toremifene; totipotent stem cell factor; translation inhibitors; tretinoin; triacetyluridine; triciribine; trimetrexate; triptorelin; tropisetron; turosteride; tyrosine kinase inhibitors; tyrphostins; UBC inhibitors; ubenimex; urogenital sinus-derived growth inhibitory factor; urokinase receptor antagonists; vapreotide; variolin B; vector system, erythrocyte gene therapy; velaresol; veramine; verdins; verteporfin; vinorelbine; vinxaltine; vitaxin; vorozole; zanoterone; zeniplatin; zilascorb; and zinostatin stimalamer. Preferred additional anti-cancer drugs are 5-fluorouracil and leucovorin.

[0470] Examples of therapeutic antibodies that can be used in methods of the invention include but are not limited to ZENAPAX® (daclizumab) (Roche Pharmaceuticals, Switzerland) which is an immunosuppressive, humanized anti-CD25 monoclonal antibody for the prevention of acute renal allograft rejection; PANOREX™ which is a murine anti-17-IA cell surface antigen IgG2a antibody (Glaxo Wellcome/Centocor); BEC2 which is a murine anti-idiotype (GD3 epitope) IgG antibody (ImClone System); IMC-C225 which is a chimeric anti-EGFR IgG antibody (ImClone System); VITAXIN™ which is a humanized anti-αVβ3 integrin antibody (Applied Molecular Evolution/MedImmune); Smart M195 which is a humanized anti-CD33 IgG antibody (Protein Design Lab/Kanebo); LYMPHOCIDE™ which is a humanized anti-CD22 IgG antibody (Immunomedics); ICM3 is a humanized anti-ICAM3 antibody (ICOS Pharm); IDEC-114 is a primatied anti-CD80 antibody (IDEC Pham/Mitsubishi); IDEC-131 is a humanized anti-CD40L antibody (IDEC/Eisai); IDEC-151 is a primatized anti-CD4 antibody (IDEC); IDEC-152 is a primatized anti-CD23 antibody (IDEC/Seikagaku); SMART anti-CD3 is a humanized anti-CD3 IgG (Protein Design Lab); 5G1.1 is a humanized anti-complement factor 5 (C5) antibody (Alexion Pharm); D2E7 is a humanized anti-TNF-α antibody (CAT/BASF); CDP870 is a humanized anti-TNF-α Fab fragment (Celltech); IDEC-151 is a primatized anti-CD4 IgG1 antibody (IDEC Pharm/SmithKline Beecham); MDX-CD4 is a human anti-CD4 IgG antibody (Medarex/Eisai/Genmab); CDP571 is a humanized anti-TNF-α IgG4 antibody (Celltech); LDP-02 is a humanized anti-α4β7 antibody (LeukoSite/Genentech); OrthoClone OKT4A is a humanized anti-CD4 IgG antibody (Ortho Biotech); ANTOVA™ is a humanized anti-CD40L IgG antibody (Biogen); ANTEGREN™ is a humanized anti-VLA-4 IgG antibody (Elan); and CAT-152 is a human anti-TGF-β₂ antibody (Cambridge Ab Tech). Other examples of therapeutic antibodies that can be used in accordance with the invention are presented in Table 9.

[0471] 5.4.2 Autoimmune Disease and Inflammatory Diseases

[0472] In some embodiments, molecules of the invention comprise a variant Fc region, having one or more amino acid modifications in one or more regions, which modification increases the affinity of the variant Fc region for FcγRIIB but decreases the affinity of the variant Fc region for FcγRIIIA and/or FcγRIIA. Molecules of the invention with such binding characteristics are useful in regulating the immune response, e.g., in inhibiting the immune response in connection with autoimmune diseases or inflammatory diseases. Although not intending to be bound by any mechanism of action, molecules of the invention with an enhanced affinity for FcγRIIB and a decreased affinity for FcγRIIIA and/or FcγRIIA may lead to dampening of the activating response to FcγR and inhibition of cellular responsiveness.

[0473] In some embodiments, a molecule of the invention comprising a variant Fc region is not an immunoglobulin, and comprises at least one amino acid modification which modification increases the affinity of the variant Fc region for FcγRIIB relative to a molecule comprising a wild-type Fc region. In other embodiments, said molecule further comprises one or more amino acid modifications, which modifications decreases the affinity of the molecule for an activating FcγR. In some embodiments, the molecule is a soluble (i.e., not membrane bound) Fc region. The invention contemplates other amino acid modifications within the soluble Fc region which modulate its affinity for various Fc receptors, including those known to one skilled in the art as described herein. In other embodiments, the molecule (e.g., the Fc region comprising at least one or more amino acid modification) is modified using techniques known to one skilled in the art and as described herein to increase the in vivo half life of the Fc region. Such molecules have therapeutic utility in treating and/or preventing an autoimmune disorder. Although not intending to be bound by any mechanism of actions, such molecules with enhanced affinity for FcγRIIB will lead to a dampening of the activating receptors and thus a dampening of the immune response and have therapeutic efficacy for treating and/or preventing an autoimmune disorder.

[0474] In certain embodiments, the one or more amino acid modifications, which increase the affinity of the variant Fc region for FcγRIIB but decrease the affinity of the variant Fc region for FcγRIIIA comprise a substitution at position 246 with threonine and at position 396 with histidine; or a substitution at position 268 with aspartic acid and at position 318 with aspartic acid; or a substitution at position 217 with serine, at position 378 with valine, and at position 408 with arginine; or a substitution at position 375 with cysteine and at position 396 with leucine; or a substitution at position 246 with isoleucine and at position 334 with asparagine. In one embodiment, the one or more amino acid modifications, which increase the affinity of the variant Fc region for FcγRIIB but decrease the affinity of the variant Fc region for FcγRIIIA comprise a substitution at position 247 with leucine. In another embodiment, the one or more amino acid modification, which increases the affinity of the variant Fc region for FcγRIIB but decreases the affinity of the variant Fc region for FcγRIIIA comprise a substitution at position 372 with tyrosine. In yet another embodiment, the one or more amino acid modification, which increases the affinity of the variant Fc region for FcγRIIB but decreases the affinity of the variant Fc region for FcγRIIIA comprise a substitution at position 326 with glutamic acid. In one embodiment, the one or more amino acid modification, which increases the affinity of the variant Fc region for FcγRIIB but decreases the affinity of the variant Fc region for FcγRIIIA comprise a substitution at position 224 with leucine.

[0475] The variant Fc regions that have an enhanced affinity for FcγRIIB and a decreased affinity for FcγRIIIA and/or FcγRIIA relative to a comparable molecule comprising a wild-type Fc region, may be used to treat or prevent autoimmune diseases or inflammatory diseases. The present invention provides methods of preventing, treating, or managing one or more symptoms associated with an autoimmune or inflammatory disorder in a subject, comprising administering to said subject a therapeutically or prophylactically effective amount of one or more molecules of the invention with variant Fc regions that have an enhanced affinity for FcγRIIB and a decreased affinity for FcγRIIIA and or FcγRIIA relative to a comparable molecule comprising a wild type Fc region.

[0476] The invention also provides methods for preventing, treating, or managing one or more symptoms associated with an inflammatory disorder in a subject further comprising, administering to said subject a therapeutically or prophylactically effective amount of one or more anti-inflammatory agents. The invention also provides methods for preventing, treating, or managing one or more symptoms associated with an autoimmune disease further comprising, administering to said subject a therapeutically or prophylactically effective amount of one or more immunomodulatory agents. Section 5.4.2.1 provides non-limiting examples of anti-inflammatory agents and immunomodulatory agents.

[0477] Examples of autoimmune disorders that may be treated by administering the molecules of the present invention include, but are not limited to, alopecia areata, ankylosing spondylitis, antiphospholipid syndrome, autoimmune Addison's disease, autoimmune diseases of the adrenal gland, autoimmune hemolytic anemia, autoimmune hepatitis, autoimmune oophoritis and orchitis, autoimmune thrombocytopenia, Behcet's disease, bullous pemphigoid, cardiomyopathy, celiac sprue-dermatitis, chronic fatigue immune dysfunction syndrome (CFIDS), chronic inflammatory demyelinating polyneuropathy, Churg-Strauss syndrome, cicatrical pemphigoid, CREST syndrome, cold agglutinin disease, Crohn's disease, discoid lupus, essential mixed cryoglobulinemia, fibromyalgia-fibromyositis, glomerulonephritis, Graves' disease, Guillain-Barre, Hashimoto's thyroiditis, idiopathic pulmonary fibrosis, idiopathic thrombocytopenia purpura (ITP), IgA neuropathy, juvenile arthritis, lichen planus, lupus erthematosus, Ménière's disease, mixed connective tissue disease, multiple sclerosis, type 1 or immune-mediated diabetes mellitus, myasthenia gravis, pemphigus vulgaris, pernicious anemia, polyarteritis nodosa, polychrondritis, polyglandular syndromes, polymyalgia rheumatica, polymyositis and dermatomyositis, primary agammaglobulinemia, primary biliary cirrhosis, psoriasis, psoriatic arthritis, Raynauld's phenomenon, Reiter's syndrome, Rheumatoid arthritis, sarcoidosis, scleroderma, Sjögren's syndrome, stiff-man syndrome, systemic lupus erythematosus, lupus erythematosus, takayasu arteritis, temporal arteristis/giant cell arteritis, ulcerative colitis, uveitis, vasculitides such as dermatitis herpetiformis vasculitis, vitiligo, and Wegener's granulomatosis. Examples of inflammatory disorders include, but are not limited to, asthma, encephilitis, inflammatory bowel disease, chronic obstructive pulmonary disease (COPD), allergic disorders, septic shock, pulmonary fibrosis, undifferentiated spondyloarthropathy, undifferentiated arthropathy, arthritis, inflammatory osteolysis, and chronic inflammation resulting from chronic viral or bacteria infections. As described herein in Section 2.2.2, some autoimmune disorders are associated with an inflammatory condition. Thus, there is overlap between what is considered an autoimmune disorder and an inflammatory disorder. Therefore, some autoimmune disorders may also be characterized as inflammatory disorders. Examples of inflammatory disorders which can be prevented, treated or managed in accordance with the methods of the invention include, but are not limited to, asthma, encephilitis, inflammatory bowel disease, chronic obstructive pulmonary disease (COPD), allergic disorders, septic shock, pulmonary fibrosis, undifferentiated spondyloarthropathy, undifferentiated arthropathy, arthritis, inflammatory osteolysis, and chronic inflammation resulting from chronic viral or bacteria infections.

[0478] Molecules of the invention with variant Fc regions that have an enhanced affinity for FcγRIIB and a decreased affinity for FcγRIIIA relative to a comparable molecule comprising a wild-type Fc region can also be used to reduce the inflammation experienced by animals, particularly mammals, with inflammatory disorders. In a specific embodiment, a molecule of the invention reduces the inflammation in an animal by at least 99%, at least 95%, at least 90%, at least 85%, at least 80%, at least 75%, at least 70%, at least 60%, at least 50%, at least 45%, at least 40%, at least 45%, at least 35%, at least 30%, at least 25%, at least 20%, or at least 10% relative to the inflammation in an animal, which is not administered the said molecule.

[0479] Molecules of the invention with variant Fc regions that have an enhanced affinity for FcγRIIB and a decreased affinity for FcγRIIIA relative to a comparable molecule comprising a wild-type Fc region can also be used to prevent the rejection of transplants.

[0480] The invention further contemplates engineering any of the antibodies known in the art for the treatment and/or prevention of autoimmune disease or inflammatory disease, so that the antibodies comprise a variant Fc region comprising one or more amino acid modifications, which have been identified by the methods of the invention to have an enhanced affinity for FcγRIIB and a decreased affinity for FcγRIIIA relative to a comparable molecule comprising a wild type Fc region. A non-limiting example of the antibodies that are used for the treatment or prevention of inflammatory disorders which can be engineered according to the invention is presented in Table 10A, and a non-limiting example of the antibodies that are used for the treatment or prevention of autoimmune disorder is presented in Table 10B.

TABLE 10A
ANTIBODIES FOR INFLAMMATORY DISEASES AND
AUTOIMMUNE DISEASES THAT CAN ENGINEERED IN
ACCORDANCE WITH THE INVENTION.
Antibody	Target	Product
Name	Antigen	Type	Isotype	Sponsors	Indication
5G1.1	Complement	Humanized	IgG	Alexion	Rheumatoid
	(C5)			Pharm Inc	Arthritis
5G1.1	Complement	Humanized	IgG	Alexion	SLE
	(C5)			Pharm Inc
5G1.1	Complement	Humanized	IgG	Alexion	Nephritis
	(C5)			Pharm Inc
5G1.1-SC	Complement	Humanized	ScFv	Alexion	Cardiopulmonary
	(C5)			Pharm Inc	Bypass
5G1.1-SC	Complement	Humanized	ScFv	Alexion	Myocardial
	(C5)			Pharm Inc	Infarction
5G1.1-SC	Complement	Humanized	ScFv	Alexion	Angioplasty
	(C5)			Pharm Inc
ABX-CBL	CBL	Human		Abgenix Inc	GvHD
ABX-CBL	CD147	Murine	IgG	Abgenix Inc	Allograft rejection
ABX-IL8	IL-8	Human	IgG2	Abgenix Inc	Psoriasis
Antegren	VLA-4	Humanized	IgG	Athena/Elan	Multiple Sclerosis
Anti-	CD11a	Humanized	IgG1	Genentech	Psoriasis
CD11a				Inc/Xoma
Anti-	CD18	Humanized	Fab'2	Genentech Inc	Myocardial
CD18					infarction
Anti-	CD18	Murine	Fab'2	Pasteur-	Allograft rejection
LFA1				Merieux/
				Immunotech
Antova	CD40L	Humanized	IgG	Biogen	Allograft rejection
Antova	CD40L	Humanized	IgG	Biogen	SLE
BTI-322	CD2	Rat	IgG	Medimmune	GvHD, Psoriasis
				Inc
CDP571	TNF-alpha	Humanized	IgG4	Celltech	Crohn's
CDP571	TNF-alpha	Humanized	IgG4	Celltech	Rheumatoid
					Arthritis
CDP850	E-selectin	Humanized		Celltech	Psoriasis
Corsevin M	Fact VII	Chimeric		Centocor	Anticoagulant
D2E7	TNF-alpha	Human		CAT/BASF	Rheumatoid
					Arthritis
Hu23F2G	CD11/18	Humanized		ICOS Pharm	Multiple Sclerosis
				Inc
Hu23F2G	CD11/18	Humanized	IgG	ICOS Pharm	Stroke
				Inc
IC14	CD14			ICOS Pharm	Toxic shock
				Inc
ICM3	ICAM-3	Humanized		ICOS Pharm	Psoriasis
				Inc
IDEC-114	CD80	Primatised		IDEC	Psoriasis
				Pharm/Mitsubishi
IDEC-131	CD40L	Humanized		IDEC	SLE
				Pharm/Eisai
IDEC-131	CD40L	Humanized		IDEC	Multiple Sclerosis
				Pharm/Eisai
IDEC-151	CD4	Primatised	IgG1	IDEC	Rheumatoid
				Pharm/Glaxo	Arthritis
				SmithKline
IDEC-152	CD23	Primatised		IDEC Pharm	Asthma/Allergy
Infliximab	TNF-alpha	Chimeric	IgG1	Centocor	Rheumatoid
					Arthritis
Infliximab	TNF-alpha	Chimeric	IgG1	Centocor	Crohn's
LDP-01	beta2-	Humanized	IgG	Millennium	Stroke
	integrin			Inc
				(LeukoSite
				Inc.)
LDP-01	beta2-	Humanized	IgG	Millennium	Allograft rejection
	integrin			Inc
				(LeukoSite
				Inc.)
LDP-02	alpha4beta7	Humanized		Millennium	Ulcerative Colitis
				Inc
				(LeukoSite
				Inc.)
MAK-	TNF alpha	Murine	Fab'2	Knoll Pharm,	Toxic shock
195F				BASF
MDX-33	CD64 (FcR)	Human		Medarex/Centeon	Autoimmune
					haematogical
					disorders
MDX-	CD4	Human	IgG	Medarex/Eisai/	Rheumatoid
CD4				Genmab	Arthritis
MEDI-507	CD2	Humanized		Medimmune	Psoriasis
				Inc
MEDI-507	CD2	Humanized		Medimmune	GvHD
				Inc
OKT4A	CD4	Humanized	IgG	Ortho Biotech	Allograft rejection
OrthoClone	CD4	Humanized	IgG	Ortho Biotech	Autoimmune
OKT4A					disease
Orthoclone/	CD3	Murine	mIgG2a	Ortho Biotech	Allograft rejection
anti-CD3
OKT3
RepPro/	gpIIbIIIa	Chimeric	Fab	Centocor/Lilly	Complications of
Abciximab					coronary
					angioplasty
rhuMab-	IgE	Humanized	IgG1	Genentech/No	Asthma/Allergy
E25				vartis/Tanox
				Biosystems
SB-240563	IL5	Humanized		GlaxoSmithKline	Asthma/Allergy
SB-240683	IL-4	Humanized		GlaxoSmithKline	Asthma/Allergy
SCH55700	IL-5	Humanized		Celltech/Schering	Asthma/Allergy
Simulect	CD25	Chimeric	IgG1	Novartis	Allograft rejection
				Pharm
SMART	CD3	Humanized		Protein	Autoimmune
a-CD3				Design Lab	disease
SMART	CD3	Humanized		Protein	Allograft rejection
a-CD3				Design Lab
SMART	CD3	Humanized	IgG	Protein	Psoriasis
a-CD3				Design Lab
Zenapax	CD25	Humanized	IgG1	Protein	Allograft rejection
				Design
				Lab/Hoffman-
				La Roche