ANTIBODY HAVING ENHANCED ACTIVITY, AND METHOD FOR MODIFYING SAME

[0001] This application is a divisional of U.S. application Ser. No. 16/061,429, filed on Jun. 12, 2018, which is the National Stage of International Application No. PCT/JP2016/088299, filed on Dec. 22, 2016, which claims the benefit of Japanese Application No. 2015-253324, filed on Dec. 25, 2015.

[0002] This application contains a Sequence Listing that has been submitted electronically as an ASCII text file named SequenceListing.txt. The ASCII text file, created on Dec. 14, 2021, is 110 kilobytes in size. The material in the ASCII text file is hereby incorporated by reference in its entirety.

[0003] The present invention relates to antibodies having enhanced activity, pharmaceutical compositions comprising such antibodies as active ingredients, methods for producing them, and methods for enhancing antibody activity. More specifically, the present invention relates to bispecific antibodies having blood coagulation factor VIII (FVIII) mimetic activity higher than that of ACE910.

[0004] Antibodies are drawing attention as pharmaceuticals as they are highly stable in plasma and have few adverse effects. Of them, a number of IgG-type antibody pharmaceuticals are available on the market and many antibody pharmaceuticals are currently under development (Non-patent Documents 1, 2 and 3).

[0005] Hemophilia A is a bleeding abnormality caused by a hereditary decrease or deficiency of FVIII function. Hemophilia A patients are generally administered with an FVIII formulation for bleeding (on-demand administration). In recent years, FVIII formulations are also administered prophylactically to prevent bleeding events (preventive administration; Non-patent Documents 1 and 2). The half-life of FVIII formulations in blood is approximately 12 to 16 hours. Therefore, for continuous prevention, FVIII formulations are administered to patients three times a week (Non-patent Documents 3 and 4). In on-demand administration, FVIII formulations are also additionally administered as necessary at an interval to prevent rebleeding. In addition, the administration of FVIII formulations is intravenous. Therefore, there has been a strong need for pharmaceutical agents with a lesser burden in administration than FVIII formulations.

[0006] Occasionally, antibodies against FVIII (inhibitors) are raised in hemophilia patients. Such inhibitors counteract the effects of the FVIII formulations. For bleeding in patients who have developed inhibitors (inhibitor patients), bypassing agents are administered. Their mechanisms of action do not depend on the FVIII function, that is, the function of catalyzing the activation of blood coagulation factor X (FX) by activated blood coagulation factor IX (FIXa). Therefore, in some cases, bypassing agents cannot sufficiently stop the bleeding. Accordingly, there has been a strong need for pharmaceutical agents that are not affected by the presence of inhibitors and which functionally substitute for FVIII.

[0007] As a means for solving the problem, bispecific antibodies that functionally substitute for FVIII and their use have been reported (Patent Documents 1, 2, 3, and 4). The bispecific antibodies against FIXa and FX can functionally substitute for FVIII by positioning the two factors close to each other to exhibit FVIII mimetic activity (Non-patent Document 5). It has been reported that the FVIII mimetic activity of the antibodies can be enhanced by optimizing the affinity towards FIXa and FX (Non-patent Document 6). Furthermore, the FVIII mimetic activity of the antibodies is known to be affected by the IgG isotype, disulfide bond pattern, amino acid sequence of the hinge region, and the presence or absence of sugar chains in the Fc region (Non-patent Document 7). ACE910 having high FVIII mimetic activity, which is one of these antibodies, has been reported to exhibit hemostatic effects in monkey models of hemophilia (Non-patent Documents 8 and 9). However, there has been no report on a bispecific antibody having FVIII mimetic activity higher than that of ACE910.

[0008] [Patent Document 1] WO 2005/035754

[0009] [Patent Document 2] WO 2005/035756

[0010] [Patent Document 3] WO 2006/109592

[0011] [Patent Document 4] WO 2012/067176

[0012] [Non-patent Document 1] Blood 58, 1-13 (1981).

[0013] [Non-patent Document 2] Nature 312, 330-337 (1984).

[0014] [Non-patent Document 3] Nature 312, 337-342 (1984).

[0015] [Non-patent Document 4] Biochim. Biophys. Acta 871, 268-278 (1986).

[0016] [Non-patent Document 5] Nat Med. 2012 October; 18(10):1570-4.

[0017] [Non-patent Document 6] PLoS One. 2013; 8(2):e57479.

[0018] [Non-patent Document 7] MAbs. 2015; 7(1):120-8.

[0019] [Non-patent Document 8] J Thromb Haemost. 2014 February; 12(2):206-213.

[0020] [Non-patent Document 9] Blood. 2014 Nov. 13; 124(20):3165-71.

[0021] The present invention was achieved in view of the above circumstances. An objective of the present invention is to provide antibodies having enhanced activity, pharmaceutical compositions containing such antibodies as active ingredients, methods for producing them, methods for enhancing antibody activity, and such. More specifically, an objective of the present invention is to provide mutations in the constant region sites for preparing bispecific antibodies having FVIII mimetic activity higher than that of ACE910, and FIXa/FX bispecific antibodies having such mutations, pharmaceutical compositions containing the antibodies as active ingredients, or methods for treating hemophilia A using the pharmaceutical compositions.

[0022] To solve the above-mentioned problems, the present inventors produced ACE910 variants in which various sites of the constant regions were modified, and succeeded in discovering bispecific antibodies having FVIII mimetic activity higher than that of ACE910. The inventors also succeeded in identifying mutations that elevate the FVIII mimetic activity and discovering methods for elevating the FVIII mimetic activity by using the mutations. The present invention is based on such findings and relates to the following:

[1] A modified bispecific antibody against blood coagulation factor IX and/or activated blood coagulation factor IX and blood coagulation factor X, wherein the antibody comprises a modification of at least one amino acid residue in the constant region of the antibody, and wherein the antibody has higher blood coagulation factor VIII mimetic activity than that of a bispecific antibody, which is an antibody before the modification, in which an H chain comprising the amino acid sequence of SEQ ID NO: 1 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3, and an H chain comprising the amino acid sequence of SEQ ID NO: 2 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3;
[2] The antibody of [1], wherein the modification is a modification in a CH3 region and/or hinge region;
[3] The antibody of [2], wherein the modification in the CH3 region is a modification at position 434 according to EU numbering;
[4] The antibody of [3], wherein the modification at position 434 according to EU numbering is a modification to Tyr (Y);
[5] The antibody of [2], wherein the modification in the hinge region is a modification of positions 216 to 230 according to EU numbering to AAAC;
[6] A pharmaceutical composition comprising the antibody of any one of [1] to [5], and a pharmaceutically acceptable carrier;
[7] The composition of [6], which is a pharmaceutical composition for use in prevention and/or treatment of bleeding, a disease accompanying bleeding, or a disease caused by bleeding, wherein the disease is a disease that develops and/or progresses by a decrease or deficiency in the activity of blood coagulation factor VIII and/or activated blood coagulation factor VIII;
[8] The composition of [7], wherein the disease that develops and/or progresses by a decrease or deficiency in the activity of blood coagulation factor VIII and/or activated blood coagulation factor VIII is hemophilia A, acquired hemophilia, von Willebrand's disease, or a disease in which an inhibitor against blood coagulation factor VIII and/or activated blood coagulation factor VIII has been raised;
[9] A kit for use in a method for prevention and/or treatment of bleeding, a disease accompanying bleeding, or a disease caused by bleeding, wherein the kit comprises at least the bispecific antibody of any one of [1] to [5];
[10] A method for enhancing the blood coagulation factor VIII mimetic activity of a bispecific antibody against blood coagulation factor IX and/or activated blood coagulation factor IX and blood coagulation factor X, wherein the method modifies at least one amino acid residue in the constant region of a bispecific antibody in which an H chain comprising the amino acid sequence of SEQ ID NO: 1 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3, and an H chain comprising the amino acid sequence of SEQ ID NO: 2 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3;
[11] The method of [10], wherein the modification is a modification of at least one amino acid residue in a CH3 region and/or hinge region;
[12] The method of [11], wherein the modification in the CH3 region is a modification at position 434 according to EU numbering;
[13] The method of [12], wherein the modification at position 434 is a modification to Tyr (Y);
[14] The method of [11], wherein the modification in the hinge region is a modification of positions 216 to 230 according to EU numbering to AAAC;
[15] A method for producing a bispecific antibody against blood coagulation factor IX and/or activated blood coagulation factor IX and blood coagulation factor X, wherein the method comprises: (a) modifying at least one amino acid residue in the constant region of a bispecific antibody in which an H chain comprising the amino acid sequence of SEQ ID NO: 1 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3, and an H chain comprising the amino acid sequence of SEQ ID NO: 2 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3, which is an antibody before the modification, so that the blood coagulation factor VIII mimetic activity is enhanced compared to the antibody before the modification, by modifying a nucleic acid encoding an antibody comprising said amino acid residue; (b) culturing a host cell to express the nucleic acid; and (c) collecting the antibody from a culture of the host cell;
[16] a method for prevention and/or treatment of bleeding, a disease accompanying bleeding, or a disease caused by bleeding, which comprises the step of administering the antibody of any one of [1] to [5];
[17] the antibody of any one of [1] to [5], for use in prevention and/or treatment of bleeding, a disease accompanying bleeding, or a disease caused by bleeding;
[18] use of the antibody of any one of [1] to [5] in the manufacture of a prophylactic agent and/or a therapeutic agent for bleeding, a disease accompanying bleeding, or a disease caused by bleeding; and
[19] the method of [16] or the antibody for use of [17], or the use of [18], wherein the disease is a disease that develops and/or progresses by a decrease or deficiency in the activity of blood coagulation factor VIII and/or activated blood coagulation factor VIII, or preferably hemophilia A, acquired hemophilia, von Willebrand's disease, or a disease in which an inhibitor against blood coagulation factor VIII and/or activated blood coagulation factor VIII has been raised.

[0023] The present invention provides bispecific antibodies having FVIII mimetic activity higher than that of ACE910. Furthermore, the present invention provides mutations that elevate the FVIII mimetic activity, and methods for elevating the FVIII mimetic activity that use the mutations.

[0028] An embodiment of the present invention relates to an antibody comprising a modified constant region, which comprises a mutation of at least one amino acid residue in the constant region, and has higher activity than that of the antibody before the modification.

[0029] The “antibody comprising a constant region” in the present invention is not particularly limited as long as it is an antibody that contains a constant region, and it may be an IgG-type or bispecific antibody.

[0030] In one embodiment of the present invention, constant regions are preferably antibody constant regions, more preferably IgG1, IgG2, IgG3, and IgG4-type antibody constant regions, and even more preferably human IgG1, IgG2, IgG3, and IgG4-type antibody constant regions. Furthermore, in another embodiment of the present invention, constant regions are preferably heavy chain constant regions, more preferably IgG1, IgG2, IgG3, and IgG4-type heavy chain constant regions, and even more preferably human IgG1, IgG2, IgG3, and IgG4-type heavy chain constant regions. The amino acid sequences of the human IgG1 constant region, the human IgG2 constant region, the human IgG3 constant region, and the human IgG4 constant region are known. For the constant regions of human IgG1, human IgG2, human IgG3, and human IgG4, a plurality of allotype sequences with genetic polymorphism are described in Sequences of proteins of immunological interest, NIH Publication No. 91-3242, and any of them can be used in the present invention. Amino acid-modified constant regions of the present invention may contain other amino acid mutations or modifications, as long as they include an amino acid mutation of the present invention.

[0031] An Fc region contains the amino acid sequence derived from the heavy chain constant region of an antibody. The Fc region is a portion of the heavy chain constant region of an antibody, starting from the N terminal end of the hinge region, which corresponds to the papain cleavage site at an amino acid around position 216 according to EU numbering, and contains the hinge, CH2, and CH3 domains.

[0032] The term “hinge region” denotes an antibody heavy chain polypeptide portion in a wild-type antibody heavy chain that joins the CH1 domain and the CH2 domain, e.g., from about position 216 to about position 230 according to the EU numbering system by Kabat, or from about position 226 to about position 230 according to the EU numbering system by Kabat. The hinge regions of other IgG subclasses can be determined by alignment with the hinge region cysteine residues of the IgG1 subclass sequence.

[0033] In the present invention, “polypeptide” normally refers to a protein and peptide having a length of approximately ten amino acids or longer. Ordinarily, the polypeptides are organism-derived polypeptides, but are not particularly limited thereto, and may be, for example, polypeptides comprising an artificially designed sequence. Furthermore, they may be any native polypeptides, or synthetic polypeptides, recombinant polypeptides, or such. Additionally, fragments of the above-mentioned polypeptide are also included in the polypeptides of the present invention.

[0034] According to the methods used in the present invention, amino acid positions assigned to antibody CDR and FR are specified according to Kabat's numbering (Sequences of Proteins of Immunological Interest (National Institute of Health, Bethesda, Md., 1987 and 1991)). Herein, when an antigen-binding molecule is an antibody or antigen-binding fragment, variable region amino acids are indicated by Kabat numbering, while constant region amino acids are indicated by EU numbering based on Kabat's amino acid positions.

[0035] In one embodiment of the present invention, “modification of amino acid residue” is not particularly limited as long as it is a modification that enhances activity compared to that of the antibody before the modification, and it is preferably a modification in the CH3 region or the hinge region. Particularly preferably, it is a modification at position 434 according to EU numbering, and more preferably, it is a modification that replaces Asn (N) at position 434 according to EU numbering with Tyr (Y). Particularly preferably, it is a modification in the hinge region, and more preferably it is a modification of positions 216 to 230 according to EU numbering to AAAC. Furthermore, the present invention includes a modification of positions 216 to 230 according to EU numbering to AAAC by partially modifying positions 216 to 230 according to EU numbering. As long as the mutation mentioned above is included, other mutations may also be included.

[0036] In one embodiment of the present invention, “modification” or “modify” refers to substitution of the original amino acid residue with another amino acid residue, deletion of the original amino acid residue, addition of a new amino acid residue, and combinations thereof. Furthermore, “mutation” refers to substitution of the original amino acid residue with another amino acid residue, deletion of the original amino acid residue, addition of a new amino acid residue, and combinations thereof. Herein, the terms “modification” and “mutation” are used synonymously.

[0037] In one embodiment of the present invention, “activity” refers to, for example, the binding ability of the antibody to an antigen, a biological effect produced by binding of the antibody to an antigen, and such, but is not limited thereto. When the antibody is a bispecific antibody against blood coagulation factor IX (FIX) and/or activated blood coagulation factor IX (FIXa) and blood coagulation factor X (FX), the activity is, for example, blood coagulation factor FVIII (FVIII) mimetic activity.

[0038] For example, in the case of FVIII mimetic activity of the above-mentioned bispecific antibody, “having higher activity than that of the antibody before the modification” refers to the fact that the FVIII mimetic activity of the bispecific antibody after the modification is higher than the FVIII mimetic activity of the bispecific antibody before the modification.

[0039] FVIII is one of a series of molecules involved in blood coagulation. FVIII exhibits cofactor activity when it is activated by thrombin or FXa and promotes the FX activation reaction by FIXa.

[0040] In the present invention, “FVIII mimetic activity” can be rephrased as “FVIII function substituting activity”, “activity of functionally substituting for FVIII”, “FXa generation promoting activity”, and “activity of promoting generation of FXa”. In the present invention, the phrases “FVIII function substituting” and “functionally substituting for FVIII” means that FX activation by FIXa is promoted (FXa generation by FIXa is promoted). More specifically, in the present invention, the phrase “functionally substituting for FVIII” means recognizing FIX and/or FIXa, and FX, and promoting activation of FX by FIXa (promoting FXa generation by FIXa). The activity of promoting FXa generation can be evaluated using, for example, a measurement system comprising FIXa, FX, synthetic substrate S-2222 (synthetic substrate of FXa), and phospholipids. Such a measurement system shows correlation with the disease severity and clinical symptoms in hemophilia A cases (Rosen S, Andersson M, Blombäck M et al. Clinical applications of a chromogenic substrate method for determination of FVIII activity. Thromb Haemost 1985; 54: 811-23).

[0041] In one embodiment of the present invention, the antibody is not particularly limited but is preferably, for example, a bispecific antibody against FIX and/or FIXa and FX, which has activity of functionally substituting for FVIII. Such an antibody can be obtained according to the methods described, for example, in WO2005/035756, WO2006/109592, and WO2012/067176. Antibodies of the present invention include antibodies described in these documents.

[0042] A preferred bispecific antibody includes, for example, ACE910 (emicizumab) (Q499-z121/J327-z119/L404-k) (a bispecific antibody in which the H chain comprising the amino acid sequence of SEQ ID NO: 1 (Q chain) associates with the L chain comprising the amino acid sequence of SEQ ID NO: 3, and the H chain comprising the amino acid sequence of SEQ ID NO: 2 (J chain) associates with the L chain comprising the amino acid sequence of SEQ ID NO: 3), which is a bispecific antibody described in the patent document WO2012/067176. The L chain of this antibody is a so-called common L chain. Herein, ACE910 is also referred to as ACE910-A.

[0043] An embodiment of the present invention is a modified bispecific antibody against FIX and/or FIXa and FX, which comprises a modification of at least one amino acid residue, and has higher FVIII mimetic activity than the bispecific antibody, which is the antibody before the modification, in which an H chain comprising the amino acid sequence of SEQ ID NO: 1 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3, and an H chain comprising the amino acid sequence of SEQ ID NO: 2 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3.

[0044] A specific embodiment of the present invention is a bispecific antibody against FIX and/or FIXa and FX, in which an H chain comprising the amino acid sequence of SEQ ID NO: 1 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3, and an H chain comprising the amino acid sequence of SEQ ID NO: 2 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3, which is an antibody whose position 434 according to EU numbering is Tyr (Y).

[0045] Another specific embodiment of the present invention is a bispecific antibody against FIX and/or FIXa and FX, in which an H chain comprising the amino acid sequence of SEQ ID NO: 1 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3, and an H chain comprising the amino acid sequence of SEQ ID NO: 2 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3, which is an antibody whose positions 216 to 230 according to EU numbering are AAAC.

[0046] The term “antibody” is used in the broadest sense, and may be a monoclonal antibody, polyclonal antibody, dimer, multimer, multispecific antibody (for example, bispecific antibody), antibody derivative, and modified antibody product (Miller K et al. J Immunol. 2003, 170(9), 4854-61) as long as it show a desired activity. The antibodies may be mouse antibodies, human antibodies, humanized antibodies, chimeric antibodies, or those derived from other species, or they may be artificially synthesized antibodies. The antibodies disclosed herein can be of any type (for example, IgG, IgE, IgM, IgD, and IgA), class (for example, IgG1, IgG2, IgG3, IgG4, IgAl and IgA2) or subclass of immunoglobulin. The immunoglobulin can be derived from any species (for example, human, mouse, or rabbit). The terms “antibody”, “immune globulin” and “immunoglobulin” are used interchangeably in a broad sense.

[0047] The term “antibody derivative” includes a portion of an antibody, preferably a variable region of an antibody, or at least an antigen-binding region of an antibody. Antibody derivatives include, for example, Fab, Fab′, F(ab′)2, Fv fragments, linear antibodies, and single-chain antibodies (scFv), sc(Fv)₂, Fab₃, domain antibodies (dAb) (WO2004/058821, WO2003/002609), diabodies, triabodies, tetrabodies, minibodies, and multispecific antibodies formed from antibody derivatives, but are not limited thereto. Here, “Fab” is composed of a single light chain and the CH1 domain and variable region of a single heavy chain. Furthermore, “Fv” is the smallest antibody derivative, and includes a complete antigen-recognizing region and an antigen-binding region. Furthermore, the antibody derivative may be, for example, a fusion with an Fc of an IgG antibody. For example, one can refer to Example 2 in U.S. Pat. No. 5,641,870, specification; Zapata G et al. Protein Eng. 1995, 8(10), 1057-1062; Olafsen T et al. Protein Eng. Design & Sel. 2004, 17(4): 315-323; Holliger P et al. Nat. Biotechnol. 2005, 23(9): 1126-36; Fischer N et al. Pathobiology. 2007, 74(1): 3-14; Shen J et al. J Immunol Methods. 2007, 318, 65-74; and Wu et al. Nat Biotechnol. 2007, 25(11), 1290-7.

[0048] Examples of modified antibody products may include antibodies linked to various molecules such as polyethylene glycol (PEG). Antibodies of the present invention include such modified antibody products. The substance to be linked is not limited in the modified antibody products of the present invention. To yield such modified antibody products, chemical modifications can be made to the obtained antibodies. Such methods have already been established in this field.

[0049] “Bispecific” antibodies refer to antibodies having variable regions that recognize different epitopes within the same antibody molecule. Bispecific antibodies may be antibodies that recognize two or more different antigens, or antibodies that recognize two or more different epitopes on the same antigen. Bispecific antibodies may include not only whole antibodies but antibody derivatives. Antibodies of the present invention also include bispecific antibodies. Herein, “anti-FIXa/FX bispecific antibody” and “bispecific antibody that binds to FIXa and FX” are used synonymously.

[0050] Recombinant antibodies produced by using genetic engineering techniques can be used as the antibodies. Recombinant antibodies can be obtained by cloning DNAs encoding the antibodies from hybridomas or antibody-producing cells such as sensitized lymphocytes that produce antibodies, inserting them into vectors, and then introducing them into hosts (host cells) to produce the antibodies.

[0051] The antibodies include human antibodies, mouse antibodies, and rat antibodies, and their origin is not limited. They may also be genetically modified antibodies such as chimeric antibodies and humanized antibodies.

[0052] Methods for obtaining human antibodies have already been known. For example, transgenic animals carrying the entire repertoire of human antibody genes can be immunized with antigens of interest to obtain human antibodies of interest (see International Publication WO 93/12227, WO 92/03918, WO 94/02602, WO 94/25585, WO 96/34096, and WO 96/33735).

[0053] Genetically modified antibodies can be produced using known methods. Specifically, for example, chimeric antibodies comprise H-chain and L-chain variable regions of an antibody from an immunized animal, and H-chain and L-chain constant regions of a human antibody. Chimeric antibodies can be obtained by linking DNAs encoding the variable regions of the antibody derived from the immunized animal, with DNAs encoding the constant regions of the human antibody, inserting this into an expression vector, and then introducing it into a host to produce the antibodies.

[0054] Humanized antibodies are modified antibodies that are also referred to as reshaped human antibodies. A humanized antibody is constructed by transferring the CDRs of an antibody derived from an immunized animal to the complementarity determining regions of a human antibody. Conventional genetic recombination techniques for this are known (see European Patent Application Publication No. EP 239400; International Publication No. WO 96/02576; Sato K et al., Cancer Research 1993, 53: 851-856; and International Publication No. WO 99/51743).

[0055] Bispecific antibodies are antibodies that have specificity to two different antigens.

[0056] While bispecific antibodies are not limited to those of the IgG type, for example, IgG-type bispecific antibodies can be secreted from a hybrid hybridoma (quadroma) produced by fusing two types of hybridomas that produce IgG antibodies (Milstein C. et al., Nature 1983, 305: 537-540). They can also be secreted by introducing a total of four types of genes including the L-chain and H-chain genes constituting the two types of IgGs of interest into cells to co-express the genes.

[0057] In this case, by introducing suitable amino acid substitutions into the CH3 regions of the H chains, IgGs having a heterogeneous combination of H chains can be preferentially secreted (Ridgway J B et al. Protein Engineering 1996, 9: 617-621; Merchant A M et al. Nature Biotechnology 1998, 16: 677-681; WO 2006/106905; Davis J H et al. Protein Eng Des Sel. 2010, 4: 195-202).

[0058] Regarding the L chains, since the diversity of L chain variable regions is lower than that of H chain variable regions, one can expect to obtain a common L chain that can confer binding ability to both H chains, and the antibodies of the present invention may be antibodies comprising the common L chain. Bispecific IgGs can be efficiently expressed by introducing the genes of the common L chain and both H chains into cells.

[0059] Antibodies of the present invention can be produced by methods known to those skilled in the art. Specifically, a DNA encoding the antibody of interest is inserted into an expression vector. The insertion into the expression vector is carried out such that the expression will take place under the control of expression regulatory regions such as enhancers and promoters. Next, host cells are transformed using this expression vector to express the antibody. Appropriate combinations of the host and expression vector can be used in this step.

[0060] Expression vectors are particularly useful when using the vectors for the purpose of producing the antibody. For example, when the host is Escherichia coli such as JM109, DH5a, HB101, or XL1-Blue, the expression vectors indispensably have a promoter that permits efficient expression in E. coli, for example, lacZ promoter.

[0061] The vectors may contain a signal sequence for polypeptide secretion.

[0062] The vectors can be transferred to host cells using, for example, calcium chloride methods or electroporation methods.

[0063] In addition to the E. coli expression vectors, examples of the vectors for producing the antibody of the present invention include mammal-derived expression vectors (e.g., pcDNA3 (manufactured by Invitrogen Corp.), pEGF-BOS (Nucleic Acids. Res. 1990,18(17), p5322), pEF, and pCDM8), and insect cell-derived expression vectors (e.g., “Bac-to-BAC baculovirus expression system” (manufactured by GIBCO BRL), and pBacPAK8).

[0064] For the purpose of expression in animal cells such as CHO cells, COS cells, or NIH3T3 cells, the vectors indispensably have a promoter necessary for intracellular expression, for example, SV40 promoter (Mulligan et al., Nature (1979) 277, 108), and, more preferably, have a gene for selecting transformed cells. Examples of the genes for selecting transformed cells include drug resistance genes that can be distinguished by drugs (neomycin, G418, and such).

[0065] An exemplary method intended to stably express the gene and increase the number of intracellular gene copies is a method of transfecting CHO cells deficient in nucleic acid synthesis pathway with a vector having a DHFR gene for complementation (e.g., pCHOI) and using methotrexate (MTX) to amplify the gene. Furthermore, an exemplary method intended to transiently express the gene is a method of using COS cells having a gene which expresses an SV40 T antigen on the chromosome to transform the cells with a vector having a replication origin of SV40 (pcD, etc.).

[0066] The antibodies of the present invention obtained by the methods described above can be isolated from the inside of host cells or the outside of the cells (medium, etc.), and purified to be substantially pure, homogeneous antibodies. The antibodies can be separated and purified by methods ordinarily used for separation or purification for antibody purification, and they are not limited. For example, the antibodies can be separated and purified by appropriately selecting and combining column chromatography, filtration, ultrafiltration, salting-out, solvent precipitation, solvent extraction, distillation, immunoprecipitation, SDS-polyacrylamide gel electrophoresis, isoelectric focusing, dialysis, recrystallization, and such.

[0067] The chromatography includes, for example, affinity chromatography, ion exchange chromatography, hydrophobic chromatography, gel filtration, reverse phase chromatography, and adsorption chromatography (Strategies for Protein Purification and Characterization: A Laboratory Course Manual. Ed Daniel R. Marshak et al., Cold Spring Harbor Laboratory Press, 1996). These chromatographic methods can be conducted using liquid chromatography, for example, HPLC and FPLC. Columns used for affinity chromatography include Protein A columns and Protein G columns. Columns using Protein A include, for example, Hyper D, POROS, and Sepharose FF (GE Amersham Biosciences). The present invention includes antibodies that are highly purified using these purification methods.

[0068] The obtained antibodies can be purified to be homogeneous. Antibody separation and purification can be performed using separation and purification methods generally used for proteins. For example, without limitation, the antibodies can be separated and purified by appropriately selecting and combining column chromatography such as affinity chromatography, filtration, ultrafiltration, salting-out, dialysis, SDS-polyacrylamide gel electrophoresis, isoelectric focusing, and such (Antibodies: A Laboratory Manual. Ed Harlow and David Lane, Cold Spring Harbor Laboratory, 1988). Columns used for affinity chromatography include, for example, Protein A columns and Protein G columns.

[0069] The present invention provides a pharmaceutical composition comprising an antibody of the present invention and a pharmaceutically acceptable carrier. For example, when the antibody of the present invention is a bispecific antibody against FIX and/or FIXa and FX which has FVIII mimetic activity, the composition is expected to be, for example, a pharmaceutical (pharmaceutical composition) or a pharmaceutical agent for prevention and/or treatment of bleeding, a disease accompanying bleeding, or a disease caused by bleeding.

[0070] In the present invention, bleeding, a disease accompanying bleeding, or a disease caused by bleeding is preferably a disease that develops and/or progresses by a decrease or deficiency in the activity of FVIII and/or FVIIIa. Examples of such diseases include, but are not particularly limited to, hemophilia A, a disease in which an inhibitor against FVIII/FVIIIa has been raised, acquired hemophilia, or von Willebrand's disease mentioned above.

[0071] Another embodiment of the present invention is a kit for use in a method for prevention and/or treatment of the above-mentioned diseases, which comprises at least an antibody or a composition of the present invention. The kit may include in its package a syringe, injection needle, pharmaceutically acceptable medium, alcohol-soaked cotton, adhesive bandage, instructions describing the method of use, and the like.

[0072] Another embodiment of the present invention relates to use of an antibody or a composition of the present invention in the manufacture of prophylactic and/or therapeutic agents for bleeding, a disease accompanying bleeding, or a disease caused by bleeding.

[0073] Another embodiment of the present invention relates to a method for prevention and/or treatment of bleeding, a disease accompanying bleeding, or a disease caused by bleeding, which comprises the step of administering an antibody or a composition of the present invention.

[0074] Another embodiment of the present invention relates to an antibody or a composition of the present invention for use in prevention and/or treatment of bleeding, a disease accompanying bleeding, or a disease caused by bleeding.

[0075] Pharmaceutical compositions used for therapeutic or preventive purposes, which comprise antibodies of the present invention as active ingredients, can be formulated, as necessary, by mixing, with suitable pharmaceutically acceptable carriers, vehicles, and such that are inactive towards the antibodies. For example, sterilized water, physiological saline, stabilizers, excipients, antioxidants (such as ascorbic acid), buffers (such as phosphate, citrate, histidine, and other organic acids), antiseptics, surfactants (such as PEG and Tween), chelating agents (such as EDTA), and binders may be used. They may also comprise other low-molecular-weight polypeptides, proteins such as serum albumin, gelatin, and immunoglobulins, amino acids such as glycine, glutamine, asparagine, glutamic acid, aspartic acid, methionine, arginine, and lysine, sugars and carbohydrates such as polysaccharides and monosaccharides, and sugar alcohols such as mannitol and sorbitol. When preparing an aqueous solution for injection, physiological saline and isotonic solutions comprising glucose and other adjuvants such as D-sorbitol, D-mannose, D-mannitol, and sodium chloride may be used, and they may be used in combination with appropriate solubilizers such as alcohol (for example, ethanol), polyalcohols (such as propylene glycol and PEG), and nonionic surfactants (such as polysorbate 80, polysorbate 20, poloxamer 188, and HCO-50). By mixing hyaluronidase into the formulation, a larger fluid volume can be administered subcutaneously (Expert Opin Drug Deliv. 2007 July; 4(4): 427-40).

[0076] As necessary, antibodies of the present invention may be encapsulated in microcapsules (for example, those made of hydroxymethylcellulose, gelatin, and poly(methylmethacrylate)), or incorporated in colloidal drug delivery systems (for example, liposomes, albumin microspheres, microemulsion, nanoparticles, and nanocapsules) (see, for example, “Remington's Pharmaceutical Science 16th edition”, Oslo Ed. (1980)). Methods for preparing the pharmaceutical agents as release-controlled pharmaceutical agents are also well known, and such methods may be applied to the antibodies of the present invention (Langer et al., J. Biomed. Mater. Res. 15: 267-277 (1981); Langer, Chemtech. 12: 98-105 (1982); U.S. Pat. No. 3,773,919; European Patent Application Publication No. EP 58,481; Sidman et al., Biopolymers 22: 547-556 (1983); EP 133,988).

[0077] The dose of a pharmaceutical composition of the present invention may be appropriately determined ultimately based on the decision by the physician, considering the type of dosage form, method of administration, patient age and body weight, symptoms of the patient, type of the disease, and degree of progress of the disease. For example, in the case of the above-mentioned bispecific antibody, the dose is approximately 0.001 to approximately 1000 mg/kg per single administration. The dose is preferably approximately 0.01 mg/kg to approximately 100 mg/kg. In the case of the aforementioned bispecific antibody, the administration interval is, for example, at least one day or more. The interval is preferably one week, two weeks, four weeks, one month, three months or six months. These doses may vary depending on the patient's body weight and age, the method of administration, and such; however, appropriate selection of suitable dosage is possible by those skilled in the art. Preferably, the dosing period may also be appropriately determined depending on the therapeutic progress of the patient.

[0078] The pharmaceutical compositions of the present invention may be administered either orally or parenterally to patients. Parental administration is preferred. Specifically, such administration methods include injection, nasal administration, transpulmonary administration, and percutaneous administration. Injections include, for example, intravenous injections, intramuscular injections, intraperitoneal injections, and subcutaneous injections.

[0079] The pharmaceutical compositions of the present invention can be formulated into oral agents such as granules, powders, tablets, capsules, solutions, emulsions, and suspensions, injections, and such.

[0080] Furthermore, the present invention provides genes or nucleic acids encoding the antibodies of the present invention. In addition, gene therapy may be performed by incorporating genes or nucleic acids encoding the antibodies of the present invention into vectors for gene therapy.

[0081] Another embodiment of the present invention relates to a method for enhancing activity of an antibody containing a constant region, which is a method of modifying at least one amino acid residue in the constant region. It is preferably a method of modifying at least one amino acid residue in a CH3 region or a hinge region. It is particularly preferably a method of modifying position 434 according to EU numbering, and more preferably a method of modifying Asn (N) at position 434 according to EU numbering to Tyr (Y). It is also particularly preferably a method of modifying the hinge region, and is more preferably a method of modifying positions 216 to 230 according to EU numbering to AAAC (SEQ ID NO: 28). A method of partially modifying positions 216 to 230 according to EU numbering so that positions 216 to 230 according to EU numbering are modified to AAAC is also included in the present invention. Furthermore, as long as the modification mentioned above is included, other modifications may also be included.

[0082] Another embodiment of the present invention is a method for enhancing FVIII mimetic activity of a bispecific antibody against FIX and/or FIXa and against FX, which is a method of modifying at least one amino acid residue in the constant region of a bispecific antibody in which an H chain comprising the amino acid sequence of SEQ ID NO: 1 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3, and an H chain comprising the amino acid sequence of SEQ ID NO: 2 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3.

[0083] Another embodiment of the present invention is a method for enhancing the FVIII mimetic activity of a bispecific antibody against FIX and/or FIXa and FX, which is a method of modifying the amino acid residue at position 434 according to EU numbering to Tyr (Y) in a bispecific antibody in which an H chain comprising the amino acid sequence of SEQ ID NO: 1 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3, and an H chain comprising the amino acid sequence of SEQ ID NO: 2 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3.

[0084] Another embodiment of the present invention is a method for enhancing the FVIII mimetic activity of a bispecific antibody against FIX and/or FIXa and FX, which is a method of modifying the amino acid residues at positions 216 to 230 according to EU numbering to AAAC in a bispecific antibody in which an H chain comprising the amino acid sequence of SEQ ID NO: 1 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3, and an H chain comprising the amino acid sequence of SEQ ID NO: 2 associates with an L chain comprising the amino acid sequence of SEQ ID NO: 3.

[0085] Another embodiment of the present invention is a method for producing an antibody comprising a constant region, which comprises: (a) modifying at least one amino acid residue in a constant region so that the activity is enhanced compared to the antibody before the modification, by modifying a nucleic acid encoding an antibody comprising the amino acid residue, (b) culturing a host cell to express the nucleic acid, and (c) collecting the antibody from a culture of the host cell.

[0086] As used herein, embodiments represented by the expression “comprising . . . ” include embodiments represented by the expression “essentially consisting of . . . ” and embodiments represented by the expression “consisting of . . . ”.

[0087] All patents and reference documents explicitly cited herein are incorporated by reference into this specification in their entirety.

[0088] The present invention will be further illustrated by the following Examples, but it is not to be construed as being limited thereto.

[0089] ACE910 which is an anti-FIXa/FX bispecific antibody is an antibody having the human IgG4 isotype (J Thromb Haemost. 2014 February; 12(2):206-213). ACE910 (hereinafter, also described as ACE910-A) comprises four chains composed of three types of chains. The anti-FIXa heavy chain is called Q chain, the anti-FX heavy chain is called J chain, and the common light chain is called L chain. ACE910-A (Q, J, and L: SEQ ID NOs: 1, 2, and 3) (WO 2012/067176) was used as the control antibody.

[0090] The knobs-into-holes technology (Nat Biotechnol. 1998 July; 16(7):677-81) was used to prepare ACE910 of human IgG1, 2, and 4 types. That is, ACE910-B-IgG1 (Q, J, and L: SEQ ID NOs: 4, 5, and 3), ACE910-B-IgG2 (Q, J, and L: SEQ ID NOs: 6, 7, and 3), and ACE910-B-IgG4 (Q, J, and L: SEQ ID NOs: 8, 9, and 3) were prepared, and effects of the human IgG isotypes on the FVIII mimetic activity were evaluated.

[0091] ACE910 is an anti-FIXa/FX bispecific antibody that uses the common L chain (prepared by referring to WO2006/109592) and CH3/CH3 interface regulation (prepared by referring to WO2006/106905). Other methods for preparing bispecific antibodies have been reported (Drug Discov. Today. 2015 Jul. 20(7):838-47; WO2015/046467; WO2011/117329; and WO2013/065708). These methods were used to prepare bispecific antibodies having the variable region sequences of ACE910-A, and the effects of the methods for producing bispecific antibodies on the FVIII mimetic activity were evaluated. More specifically, ACE910-B-IgG4 (Q, J, and L: SEQ ID NOs: 8, 9, and 3), ACE910-D1 (heavy chains Q and J: SEQ ID NOs: 12 and 13) (light chains L1 and L2: SEQ ID NOs: 14 and 15) (prepared by referring to WO2011/117329), ACE910-D2 (heavy chains Q and J: SEQ ID NOs: 16 and 17) (light chains L1 and L2: SEQ ID NOs: 18 and 19) (prepared by referring to WO2011/117329), ACE910-E (heavy chains Q and J: SEQ ID NOs: 20 and 21) (light chains L1 and L2: SEQ ID NOs: 22 and 23) (prepared by referring to WO2013/065708) described below were prepared, and their FVIII mimetic activities were evaluated.

[0092] The various ACE910 variants were prepared by methods known to those skilled in the art, such as their total gene syntheses. HEK293FS (Invitrogen) was used for antibody expression, and recombinant Protein A (GE healthcare) was used for purification, and the bispecific antibodies were prepared by methods known to those skilled in the art.

[0093] The FVIII mimetic activities (FXa generation-promoting activities) of the purified bispecific antibodies were measured using the following method. All reactions were performed at room temperature. Five μL of an antibody solution diluted with Tris-buffered saline containing 0.1% bovine serum albumin (hereafter referred to as TBSB) was mixed with 5 μL of 150 ng/mL Human Factor IXa beta (Enzyme Research Laboratories), and then incubated in a 384-well plate at room temperature for 30 minutes. The enzyme reaction in this mixed solution was initiated by adding 5 μL of 24.7 μg/mL of Human Factor X (Enzyme Research Laboratories). Four minutes later, 5 μL of 0.5 M EDTA was added to stop the reaction. The coloring reaction was initiated by adding 5 μL of coloring substrate solution. After a 30-minute coloring reaction, the change in absorbance at 405 nm was measured using SpectraMax 340PC384 (Molecular Devices).

[0094] The results of comparing the activities of ACE910-B-IgG1 and ACE910-B-IgG4 are shown in FIG. 1. The FVIII mimetic activity was found to be high even for the human IgG1 isotype. In the previous reports, of anti-FIXa/FX bispecific antibodies having FVIII mimetic activities, only the human IgG4 isotypes showed high activities (Patent Documents 1, 2, 3, and 4; and Non-patent Document 7). From the results of this examination, it was found that even the human IgG1 isotype of the anti-FIXa/FX bispecific antibody has high FVIII mimetic activity.

[0095] The results of comparing the activities of ACE910-B-IgG4, ACE910-D1, ACE910-D2, and ACE910-E are shown in FIG. 2. The activities of these ACE910 variants were confirmed to be nearly equal to that of ACE910-A, and the FVIII mimetic activity of the variable regions of ACE910 was found to be unaffected by the method for producing bispecific antibodies.

[0096] Various ACE910 variants were produced by introducing mutations by methods known to those skilled in the art such as total gene synthesis or PCR, into the human IgG4 bispecific antibody ACE910-B-IgG4 (Q, J, and L: SEQ ID NOs: 8, 9, and 3) and ACE910-C (Q, J, and L: SEQ ID NOs: 10, 11, and 3) (prepared by referring to WO2015/046467), which have the same variable region sequence as ACE910-A (Q, J, and L: SEQ ID NOs: 1, 2, and 3). Antibody expression and purification were performed according to the method of Example 1. The introduced mutations are summarized in Table 1 (mutations introduced into regions other than the hinge region) and Table 2 (mutations introduced into the hinge region) below.

TABLE 1
Antibody name	Mutations introduced into the heavy chain
T01	P387R, E388R, Q311R
T03	P387R, D399R, S400R, E345R, H285R
T06	E345R, E430G, S440Y
T08	N434Y
T09	N434W
T56	E345R
T57	S440K
QH0001//	G26E (Q chain only)
JH0000
QCH0001//	A1621( (Q chain only), N208D (J chain only)
JCH0001
T63	C-terminal sequence of the L chain (SEQ ID NO: 29):-
	FNRGCE (the mutated sites are underlined)
T64	C-terminal sequence of the L chain (SEQ ID NO: 30):-
	FNRGEGC (the mutated sites are underlined)
T65	C-terminal sequence of the L chain (SEQ ID NO: 31):-
	FNRGEGGC (the mutated sites are underlined)

[0097] Of the various ACE910 variants shown in Tables 1 and 2, T08 (Q, J, and L: SEQ ID NOs: 24, 25, and 3) and T46P (Q, J, and L: SEQ ID NOs:26, 27, and 3) had elevated FVIII mimetic activity compared to the parent antibody ACE910-A. Other ACE910 variants had FVIII mimetic activities equivalent to or lower than that of ACE910. The FVIII mimetic activities of ACE910, T08 and T46P are shown in FIGS. 3 and 4.