Mouse FcγammaRII-specific Fc antibody

[0001] This application is the National Stage of International Application Serial No. PCT/JP2013/072598, filed on Aug. 23, 2013, which claims the benefit of Japanese Application Serial No. 2012-185865, filed on Aug. 24, 2012.

[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. 31, 2014, is 115 kilobytes in size. The material in the ASCII text file is hereby incorporated by reference in its entirety.

[0003] The present invention relates to a polypeptide comprising an Fc variant selectively binding to mouse FcγRII relative to mouse FcγRIII. The present invention also relates to a method for using the Fc variant to predict the effects, on a human, of a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa. The present invention further relates to a polypeptide prepared on the basis of information obtained using the method, and a therapeutic or preventive agent for a human disease, comprising the polypeptide as an active ingredient.

[0004] Antibodies have received attention as drugs because of their high stability in blood and few adverse reactions (Non Patent Literatures 1 and 2). Most of currently launched antibody drugs are antibodies of human IgG1 subclass. Antibody-dependent cell-mediated cytotoxicity (hereinafter, referred to as ADCC activity) is known as one of the functions of IgG class antibodies (Non Patent Literature 3). For exerting the ADCC activity of the antibodies, their Fc regions must bind to Fcγ receptors (hereinafter, referred to as FcγR), antibody-binding receptors, present on the surface of effector cells such as killer cells, natural killer cells, or activated macrophages.

[0005] In humans, FcγRIa (CD64A), FcγRIIa (CD32A), FcγRIIb (CD32B), FcγRIIIa (CD16A), and FcγRIIIb (CD16B) isoforms have been reported as the protein family of FcγR, and their respective allotypes have also been reported (Non Patent Literature 7). FcγRIa, FcγRIIa, and FcγRIIIa are each called activating FcγR because of having an immunologically activating function, while FcγRIIb is called inhibitory FcγR because of having an immunosuppressive function (Non Patent Literature 8).

[0006] For the binding between the Fc region and FcγR, some amino acid residues in the hinge regions and the CH2 domains of the antibody and sugar chains added to Asn 297 (EU numbering) of the CH2 domains have been found important (Non Patent Literatures 4, 5, 6, and 47). Mutants having various FcγR-binding properties have previously been studied by focusing on antibodies mutated at these sites, to yield Fc mutants having higher binding activity against activating FcγR (Patent Literatures 1, 2, 3, 4, 6, 7, and 8).

[0007] The activating FcγR, when cross-linked by an immune complex, causes the phosphorylation of immunoreceptor tyrosine-based activating motifs (ITAMs) contained in its intracellular domain or its interaction partner FcR common γ-chain, which results in the activation of a signal transducer SYK to initiate an activation signal cascade, thereby causing inflammatory immune response (Non Patent Literature 9).

[0008] FcγRIIb is the only FcγR that is expressed in B cells (Non Patent Literature 10). Reportedly, the priming of B cells is suppressed by the interaction of the Fc region of an antibody with FcγRIIb (Non Patent Literature 11). The cross-linking of FcγRIIb on B cells to a B cell receptor (BCR) via an immune complex in blood has been reported to suppress the activation of the B cells and thereby inhibit the antibody production of the B cells (Non Patent Literature 12). This immunosuppressive signal transduction mediated by BCR and FcγRIIb requires an immunoreceptor tyrosine-based inhibitory motif (ITIM) contained in the intracellular domain of FcγRIIb (Non Patent Literatures 13 and 14). In response to the signal, ITIM is phosphorylated to recruit SH2-containing inositol polyphosphate 5-phosphatase (SHIP), which in turn inhibits the transduction of other signal cascades involving activating FcγR, thereby suppressing inflammatory immune response (Non Patent Literature 15). In addition, the unique aggregation of FcγRIIb in a BCR-independent manner has been reported to transiently inhibit B cell proliferation and calcium influx triggered by BCR cross-linking without causing the apoptosis of IgM-producing B cells (Non Patent Literature 16).

[0009] FcγRIIb is also expressed in dendritic cells, macrophages, activated neutrophils, mast cells, and basophils. In these cells, FcγRIIb also inhibits the functions of activating FcγR, such as phagocytosis or the release of inflammatory cytokines, and suppresses inflammatory immune response (Non Patent Literature 8).

[0010] The importance of the immunosuppressive functions of FcγRIIb has been revealed by previous studies using FcγRIIb-knockout mice. For the FcγRIIb-knockout mice, it has been reported that: humoral immunity is not adequately regulated (Non Patent Literature 17); sensitivity to collagen-induced arthritis (CIA) is increased (Non Patent Literature 18); and lupus-like symptoms or Goodpasture's syndrome-like symptoms appear (Non Patent Literature 19).

[0011] Reportedly, the poor regulation of FcγRIIb is also associated with autoimmune disease in humans. For example, the association of a gene polymorphism in the promoter region or transmembrane region of FcγRIIb with the frequency of occurrence of systemic lupus erythematosus (SLE) (Non Patent Literatures 20, 21, 22, 23, and 24), and the decreased expression of FcγRIIb on the B cell surface of SLE patients (Non Patent Literatures 25 and 26) have been reported.

[0012] These findings from mouse models and clinical studies suggest that FcγRIIb is responsible for controlling autoimmune disease and inflammatory disease mainly by its involvement with B cells. Thus, FcγRIIb is a promising target molecule for controlling autoimmune disease and inflammatory disease.

[0013] IgG1, which is predominantly used as a commercially available antibody drug, is known to strongly bind not only to FcγRIIb but to activating FcγR (Non Patent Literature 27). It is considered that an antibody drug having immunosuppressive properties compared with the properties of IgG1 may be developed by use of an Fc mutant with enhanced binding to FcγRIIb or improved binding selectivity for FcγRIIb relative to activating FcγR. For example, the possibility is suggested that B cell activation is inhibited by use of an antibody having a variable region binding to BCR, and an Fc mutant with enhanced binding to FcγRIIb (Non Patent Literature 28). The cross-linking of FcγRIIb on B cells to IgE bound with a B cell receptor has been reported to inhibit the differentiation of the B cells into plasma cells and the resultant IgE production, thereby decreasing human IgE concentrations in human PBMC-transplanted mice while maintaining human IgG or IgM concentrations (Non Patent Literature 29). IgE-mediated as well as antibody-mediated cross-linking of CD79b and FcγRIIB that form a B cell receptor complex has been reported to inhibit B cell proliferation in vitro and to alleviate symptoms in collagen-induced arthritis models (Non Patent Literature 30).

[0014] As for cells other than B cells, FcεRI-FcγRIIb cross-linking on mast cells using a molecule in which the Fc domain of IgE binding to an IgE receptor FcεRI is fused with the Fc domain of IgG with enhanced binding to FcγRIIb has been reported to cause the phosphorylation of FcγRIIb, thereby suppressing FcεRI-dependent calcium influx. This suggests that the enhanced binding to FcγRIIb may inhibit degranulation through the stimulation of FcγRIIb (Non Patent Literature 31).

[0015] These findings imply that an antibody having an Fc mutant with improved binding activity against FcγRIIb is promising as a therapeutic drug for inflammatory diseases such as autoimmune disease.

[0016] It is also suggested that a mutant with enhanced binding to FcγRIIb is promising as a therapeutic drug for inflammatory diseases such as autoimmune disease as well as a therapeutic drug for cancer. FcγRIIb has previously been shown to also play an important role in the agonistic activity of agonist antibodies against the TNF receptor family. Specifically, it is suggested that the agonistic activity of antibodies against CD40, DR4, DR5, CD30, and CD137 included in the TNF receptor family requires interaction with FcγRIIb (Non Patent Literatures 32, 33, 34, 35, 36, and 37). Non Patent Literature 32 indicates that use of an antibody with enhanced binding to FcγRIIb enhances the antitumor effect of an anti-CD40 antibody. Thus, such an antibody with enhanced binding to FcγRIIb is expected to be effective for enhancing the agonistic effects of agonist antibodies including antibodies against the TNF receptor family.

[0017] There has been a report on an antibody having an Fc mutant with improved binding activity against FcγRIIb (Non Patent Literature 28). In this literature, alterations such as S267E/L328F, G236D/S267E, or S239D/S267E were added to the Fc regions of antibodies to thereby improve their binding activity against FcγRIIb. Among them, the S267E/L328F mutant antibody bound most strongly to FcγRIIb and maintained the same level of binding to FcγRIa and FcγRIIa H type as that of naturally occurring IgG1. According to another report, however, this alteration enhanced binding to FcγRIIa R type by several hundred times which are the same level as in binding to FcγRIIb. This means that binding selectivity for FcγRIIb relative to FcγRIIa R type is not improved (Patent Literature 5). In this literature, the binding activity of this S267E/L328F mutant antibody against mouse FcγRII (mouse homolog of FcγRIIb) was evaluated, but was not enhanced, suggesting the low species cross-reactivity of enhancement in FcγRIIb binding.

[0018] Some antibody drugs have been reported to produce adverse reactions derived from the interaction between IgG and FcγR. For example, a patient group that has received bevacizumab, an antibody against VEGF, is known to exhibit a rise in the incidence of thromboembolism (Non Patent Literature 38). Also, thromboembolism was observed in the clinical development trial of antibodies against CD40 ligand, and this clinical trial was discontinued (Non Patent Literature 39). The activating Fcγ receptor FcγRIIa is expressed on platelet cells (Non Patent Literature 40). Subsequent studies using animal models or the like suggest that all administered antibodies aggregate platelets via binding to FcγRIIa on the platelets, resulting in the formation of thrombus (Non Patent Literatures 41 and 42). It has been reported as to patients with systemic lupus erythematosus, which is an autoimmune disease, that an FcγRIIa-dependent mechanism causes platelet activation, which in turn correlates with the severity of the disease (Non Patent Literature 43).

[0019] Previous studies using animal models have also reported that immune complexes of antibodies and multivalent antigens induce anaphylaxis via activating FcγR (Non Patent Literature 44).

[0020] In addition, the activating FcγR-mediated uptake of immune complexes of multivalent antigens and antibodies has been reported to produce higher levels of antibodies against the antigens (Non Patent Literatures 45 and 46). This result suggests that, in the case of antibody drugs recognizing multivalent antigens, antibodies against the antibody drugs themselves may be more likely to be produced. Such produced antibodies against the antibody drugs are thought to deteriorate the kinetics of the drugs in blood or to cause neutralizing antibodies to reduce the effects of the drugs.

[0021] Thus, immune complexes are formed through the binding of antibodies to multivalent antigens and seem to induce various adverse reactions by their interaction with activating FcγR. This reduces the values of the antibodies as drugs. For circumventing this problem while maintaining the effects mediated by FcγRIIb, it is desirable to maintain binding to FcγRIIb and, at the same time, to selectively reduce binding to activating FcγR. Nonetheless, there has been no report on an Fc mutant that has such features in relation to mouse FcγR.

[0022] As mentioned above, there has been a report on an Fc mutant with partially improved binding selectivity for FcγRIIb in relation to human FcγR, whereas there has been no report on an Fc mutant with improved binding selectivity for its corresponding homolog FcγRII in relation to mouse FcγR. Owing to the absence of such an Fc mutant, the effects of the Fc mutant selectively binding to FcγRIIb have not been thoroughly tested yet in various disease models established using mice. The effects of the Fc mutant selectively binding to FcγRIIb have heretofore been evaluated by testing methods using, for example, human FcγRIIb transgenic mice (Non Patent Literatures 30, 31, and 32) or human PBMC-transplanted SCID mice (Non Patent Literatures 29 and 31). The former method, however, fails to test the effects of the Fc mutant selectively binding to FcγRIIb on disease models without mating with the disease models. Unfortunately, the transgenes in the transgenic mice thus do not always exert their original functions. The latter method fails to evaluate only the effects mediated by human FcγRIIb, because blood cells express human FcγRIIb but the other tissues express mouse-derived FcγR. For these reasons, the effects of the Fc mutant selectively binding to FcγRIIb have not been thoroughly evaluated yet in various disease models established using mice. If an Fc mutant selectively binding to mouse FcγRII can be developed, its effects on various mouse models of diseases can be tested without constraints as mentioned above. In addition, such an Fc mutant is very useful in determining the effects of an Fc mutant selectively binding to FcγRIIb on humans. From such viewpoints, there has been a demand for the development of an Fc mutant selectively binding to mouse FcγRII.

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[0078] The present invention has been made in light of these circumstances, and an object of the present invention is to provide a polypeptide comprising an Fc variant selectively binding to mouse FcγRII relative to mouse FcγRIII. Another object of the present invention is to provide a method for using the Fc variant to predict the effects, on a human, of a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa. A further object of the present invention is to provide a polypeptide prepared on the basis of information obtained using the method, and a therapeutic or preventive agent for a human disease, comprising the polypeptide as an active ingredient.

[0079] The present inventors have conducted diligent studies on a polypeptide comprising an Fc variant selectively binding to mouse FcγRII relative to mouse FcγRIII. As a result, the present inventors have successfully found a large number of Fc variants with remarkably increased binding activity against and/or binding selectivity for mouse FcγRII by introducing amino acid alteration(s) to the Fc region.

[0080] The present invention is based on these findings and specifically relates to the following aspects:

[0081] [1] A polypeptide which is a variant of a parent polypeptide comprising an Fc region, wherein the polypeptide comprises at least one amino acid alteration in the Fc region and has a ratio of [KD value for mouse FcγRIII]/[KD value for mouse FcγRII] of 6 or more.
[2] A polypeptide which is a variant of a parent polypeptide comprising an Fc region, wherein the polypeptide comprises at least one amino acid alteration in the Fc region and the binding selectivity of the polypeptide for mouse FcγRII relative to mouse FcγRIII is improved by 5 times or more compared with that of the parent polypeptide.
[3] The polypeptide according to [1] or [2], wherein the KD value for mouse FcγRII is 20 nM or smaller.
[4] The polypeptide according to [1] or [2], wherein the binding activity of the polypeptide against mouse FcγRII is enhanced by 10 times or more compared with that of the parent polypeptide.
[5] The polypeptide according to any of [1] to [4], wherein the KD value for mouse FcγRIII is 1 μM or larger.
[6] The polypeptide according to any of [1] to [4], wherein the binding activity of the polypeptide against mouse FcγRIII is reduced to 0.25 times or less compared with that of the parent polypeptide.
[7] The polypeptide according to any of [1] to [6], wherein the amino acid alteration is the alteration of at least one amino acid selected from the group consisting of amino acids at EU numbering positions 230, 231, 232, 237, 238, 239, 240, 241, 266, 267, 268, 271, 295, 296, 298, 324, 326, 327, 330, 331, 333, 334, 335, and 337.
[8] The polypeptide according to [7], wherein the amino acid alteration is at least one alteration selected from the group consisting of:
the substitution of an amino acid at position 230 by Asp, Glu, Ile, Pro, Gln, or Val,
the substitution of an amino acid at position 231 by Ala, Asp, Glu, Ile, Leu, Met, Asn, Pro, Gln, Thr, or Trp,
the substitution of an amino acid at position 232 by Ala, Asp, Glu, Phe, Lys, Leu, Asn, Val, Trp, or Tyr,
the substitution of an amino acid at position 237 by Glu,
the substitution of an amino acid at position 238 by Asp, Glu, Pro, or Gln,
the substitution of an amino acid at position 239 by Ala, Asp, Glu, Phe, Gly, His, Ile, Lys, Leu, Met, Asn, Pro, Gln, Arg, Thr, Val, Trp, or Tyr,
the substitution of an amino acid at position 240 by Glu, His, Gln, or Trp,
the substitution of an amino acid at position 241 by Asp, Glu, Thr, Trp, or Tyr,
the substitution of an amino acid at position 266 by Leu,
the substitution of an amino acid at position 267 by Ala, Glu, or Met,
the substitution of an amino acid at position 268 by Asp,
the substitution of an amino acid at position 271 by Leu,
the substitution of an amino acid at position 295 by Leu,
the substitution of an amino acid at position 296 by Glu, Asn, Thr, or Trp,
the substitution of an amino acid at position 298 by His, Leu, or Met,
the substitution of an amino acid at position 324 by Asp, Leu, or Met,
the substitution of an amino acid at position 326 by Asp,
the substitution of an amino acid at position 327 by Gly,
the substitution of an amino acid at position 330 by Gly, Lys, or Gln,
the substitution of an amino acid at position 331 by Asp, Phe, or Tyr,
the substitution of an amino acid at position 333 by Asn, Val, or Tyr,
the substitution of an amino acid at position 334 by Arg,
the substitution of an amino acid at position 335 by Asn or Tyr, and
the substitution of an amino acid at position 337 by Ile, Lys, or Trp
(wherein all positions are indicated by EU numbering).
[9] The polypeptide according to any of [1] to [8], wherein the Fc region is the Fc region of mouse IgG1.
[10] The polypeptide according to any of [1] to [9], wherein the polypeptide is an antibody.
[11] A method for altering a parent polypeptide comprising an Fc region to adjust a ratio of [KD value for mouse FcγRIII]/[KD value for mouse FcγRII] to 6 or more, the method comprising altering at least one amino acid selected from the group consisting of amino acids at EU numbering positions 230, 231, 232, 237, 238, 239, 240, 241, 266, 267, 268, 271, 295, 296, 298, 324, 326, 327, 330, 331, 333, 334, 335, and 337 of the Fc region.
[12] A method for altering a parent polypeptide comprising an Fc region to improve the binding selectivity of the variant for mouse FcγRII relative to mouse FcγRIII by 5 times or more compared with that of the parent polypeptide, the method comprising altering at least one amino acid selected from the group consisting of amino acids at EU numbering positions 230, 231, 232, 237, 238, 239, 240, 241, 266, 267, 268, 271, 295, 296, 298, 324, 326, 327, 330, 331, 333, 334, 335, and 337 of the Fc region.
[13] The method according to [11] or [12], wherein the amino acid alteration is at least one alteration selected from the group consisting of:
the substitution of an amino acid at position 230 by Asp, Glu, Ile, Pro, Gln, or Val,
the substitution of an amino acid at position 231 by Ala, Asp, Glu, Ile, Leu, Met, Asn, Pro, Gln, Thr, or Trp,
the substitution of an amino acid at position 232 by Ala, Asp, Glu, Phe, Lys, Leu, Asn, Val, Trp, or Tyr,
the substitution of an amino acid at position 237 by Glu,
the substitution of an amino acid at position 238 by Asp, Glu, Pro, or Gln,
the substitution of an amino acid at position 239 by Ala, Asp, Glu, Phe, Gly, His, Ile, Lys, Leu, Met, Asn, Pro, Gln, Arg, Thr, Val, Trp, or Tyr,
the substitution of an amino acid at position 240 by Glu, His, Gln, or Trp,
the substitution of an amino acid at position 241 by Asp, Glu, Thr, Trp, or Tyr,
the substitution of an amino acid at position 266 by Leu,
the substitution of an amino acid at position 267 by Ala, Glu, or Met,
the substitution of an amino acid at position 268 by Asp,
the substitution of an amino acid at position 271 by Leu,
the substitution of an amino acid at position 295 by Leu,
the substitution of an amino acid at position 296 by Glu, Asn, Thr, or Trp,
the substitution of an amino acid at position 298 by His, Leu, or Met,
the substitution of an amino acid at position 324 by Asp, Leu, or Met,
the substitution of an amino acid at position 326 by Asp,
the substitution of an amino acid at position 327 by Gly,
the substitution of an amino acid at position 330 by Gly, Lys, or Gln,
the substitution of an amino acid at position 331 by Asp, Phe, or Tyr,
the substitution of an amino acid at position 333 by Asn, Val, or Tyr,
the substitution of an amino acid at position 334 by Arg,
the substitution of an amino acid at position 335 by Asn or Tyr, and
the substitution of an amino acid at position 337 by Ile, Lys, or Trp (wherein all positions are indicated by EU numbering).
[14] The method according to any of [11] to [13], wherein the Fc region is the Fc region of mouse IgG1.
[15] The method according to any of [11] to [14], wherein the polypeptide is an antibody.
[16] A method for producing a polypeptide which is a variant of a parent polypeptide comprising an Fc region, wherein the polypeptide has a ratio of [KD value for mouse FcγRIII]/[KD value for mouse FcγRII] of 6 or more, the method comprising altering at least one amino acid selected from the group consisting of amino acids at EU numbering positions 230, 231, 232, 237, 238, 239, 240, 241, 266, 267, 268, 271, 295, 296, 298, 324, 326, 327, 330, 331, 333, 334, 335, and 337 of the Fc region.
[17] A method for producing a polypeptide which is a variant of a parent polypeptide comprising an Fc region, wherein the binding selectivity of the polypeptide for mouse FcγRII relative to mouse FcγRIII is improved by 5 times or more compared with that of the parent polypeptide, the method comprising altering at least one amino acid selected from the group consisting of amino acids at EU numbering positions 230, 231, 232, 237, 238, 239, 240, 241, 266, 267, 268, 271, 295, 296, 298, 324, 326, 327, 330, 331, 333, 334, 335, and 337 of the Fc region.
[18] The method according to [16] or [17], wherein the amino acid alteration is at least one alteration selected from the group consisting of:
the substitution of an amino acid at position 230 by Asp, Glu, Ile, Pro, Gln, or Val,
the substitution of an amino acid at position 231 by Ala, Asp, Glu, Ile, Leu, Met, Asn, Pro, Gln, Thr, or Trp,
the substitution of an amino acid at position 232 by Ala, Asp, Glu, Phe, Lys, Leu, Asn, Val, Trp, or Tyr,
the substitution of an amino acid at position 237 by Glu,
the substitution of an amino acid at position 238 by Asp, Glu, Pro, or Gln,
the substitution of an amino acid at position 239 by Ala, Asp, Glu, Phe, Gly, His, Ile, Lys, Leu, Met, Asn, Pro, Gln, Arg, Thr, Val, Trp, or Tyr,
the substitution of an amino acid at position 240 by Glu, His, Gln, or Trp,
the substitution of an amino acid at position 241 by Asp, Glu, Thr, Trp, or Tyr,
the substitution of an amino acid at position 266 by Leu,
the substitution of an amino acid at position 267 by Ala, Glu, or Met,
the substitution of an amino acid at position 268 by Asp,
the substitution of an amino acid at position 271 by Leu,
the substitution of an amino acid at position 295 by Leu,
the substitution of an amino acid at position 296 by Glu, Asn, Thr, or Trp,
the substitution of an amino acid at position 298 by His, Leu, or Met,
the substitution of an amino acid at position 324 by Asp, Leu, or Met,
the substitution of an amino acid at position 326 by Asp,
the substitution of an amino acid at position 327 by Gly,
the substitution of an amino acid at position 330 by Gly, Lys, or Gln,
the substitution of an amino acid at position 331 by Asp, Phe, or Tyr,
the substitution of an amino acid at position 333 by Asn, Val, or Tyr,
the substitution of an amino acid at position 334 by Arg,
the substitution of an amino acid at position 335 by Asn or Tyr, and
the substitution of an amino acid at position 337 by Ile, Lys, or Trp
(wherein all positions are indicated by EU numbering).
[19] The method according to any of [16] to [18], wherein the Fc region is the Fc region of mouse IgG1.
[20] The method according to any of [16] to [19], wherein the polypeptide is an antibody.
[21] A polypeptide produced by a method according to any of [16] to [20].
[22] A polypeptide which is a variant of a parent polypeptide comprising a mouse Fc region, wherein the polypeptide comprises, in the Fc region, at least one amino acid alteration selected from the group consisting of:
the substitution of an amino acid at position 230 by Asp, Glu, Ile, Pro, Gln, or Val,
the substitution of an amino acid at position 231 by Ala, Asp, Glu, Ile, Leu, Met, Asn, Pro, Gln, Thr, or Trp,
the substitution of an amino acid at position 232 by Ala, Asp, Glu, Phe, Lys, Leu, Asn, Val, Trp, or Tyr,
the substitution of an amino acid at position 237 by Glu,
the substitution of an amino acid at position 238 by Asp, Glu, Pro, or Gln,
the substitution of an amino acid at position 239 by Ala, Phe, Gly, His, Ile, Lys, Leu, Met, Asn, Pro, Gln, Arg, Thr, Val, Trp, or Tyr,
the substitution of an amino acid at position 240 by Glu, His, Gln, or Trp,
the substitution of an amino acid at position 241 by Asp, Glu, Thr, Trp, or Tyr,
the substitution of an amino acid at position 266 by Leu,
the substitution of an amino acid at position 267 by Glu or Met,
the substitution of an amino acid at position 268 by Asp,
the substitution of an amino acid at position 271 by Leu,
the substitution of an amino acid at position 295 by Leu,
the substitution of an amino acid at position 296 by Glu, Asn, Thr, or Trp,
the substitution of an amino acid at position 298 by His, Leu, or Met,
the substitution of an amino acid at position 324 by Asp, Leu, or Met,
the substitution of an amino acid at position 326 by Asp,
the substitution of an amino acid at position 327 by Gly,
the substitution of an amino acid at position 330 by Gly, Lys, or Gln,
the substitution of an amino acid at position 331 by Asp, Phe, or Tyr,
the substitution of an amino acid at position 333 by Asn, Val, or Tyr,
the substitution of an amino acid at position 334 by Arg,
the substitution of an amino acid at position 335 by Asn or Tyr, and
the substitution of an amino acid at position 337 by Ile, Lys, or Trp
(wherein all positions are indicated by EU numbering).
[23] The polypeptide according to [22], wherein the polypeptide further comprises amino acid alteration(s) selected from the group consisting of:
the substitution of an amino acid at position 239 by Asp or Glu, and
the substitution of an amino acid at position 267 by Ala
(wherein all positions are indicated by EU numbering).
[24] The polypeptide according to [22] or [23], wherein the Fc region is the Fc region of mouse IgG1.
[25] The polypeptide according to any of [22] to [24], wherein the polypeptide is an antibody.
[26] A method for predicting a therapeutic or preventive effect on a disease when a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa is administered to a human, the method comprising the following steps:
(a) obtaining a polypeptide comprising an antigen-binding region binding to a mouse antigen;
(b) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and an Fc variant according to any of [1] to [10] and [21] to [25];
(c) administering the polypeptide prepared in step (b) to a mouse model of a human disease; and
(d) when a therapeutic or preventive effect on the disease is observed in the mouse as a result of step (c), determining that a polypeptide comprising an antigen-binding region binding to a human counterpart of the mouse antigen, and the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa is effective for the treatment or prevention of the human disease.
[27] The method according to [26], wherein the method further comprises, in addition to steps (b) and (c):
(b′) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and the Fc region of naturally occurring IgG; and
(c′) administering the polypeptide prepared in step (b′) to a mouse model of a human disease, and step (d) is the step of
(d) when a stronger therapeutic or preventive effect on the disease is observed in the mouse that has received the polypeptide of step (b) than in the mouse that has received the polypeptide of step (b′) as a result of steps (c) and (c′), determining that a polypeptide comprising an antigen-binding region binding to a human counterpart of the mouse antigen, and the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa is effective for the treatment or prevention of the human disease.
[28] A method for selecting a disease suitable for treatment or prevention using a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa, the method comprising the following:
(a) obtaining a polypeptide comprising an antigen-binding region binding to a mouse antigen;
(b) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and an Fc variant according to any of [1] to [10] and [21] to [25];
(c) administering the polypeptide prepared in step (b) to a mouse model of a human disease; and
(d) when a therapeutic or preventive effect on the disease is observed in the mouse as a result of step (c), selecting the human disease as the disease suitable for treatment or prevention using a polypeptide comprising an antigen-binding region binding to a human counterpart of the mouse antigen, and the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa.
[29] The method according to [28], wherein the method further comprises, in addition to steps (b) and (c):
(b′) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and the Fc region of naturally occurring IgG; and
(c′) administering the polypeptide prepared in step (b′) to a mouse model of a human disease, and step (d) is the step of
(d) when a stronger therapeutic or preventive effect on the disease is observed in the mouse that has received the polypeptide of step (b) than in the mouse that has received the polypeptide of step (b′) as a result of steps (c) and (c′), selecting the human disease as the disease suitable for treatment or prevention using a polypeptide comprising an antigen-binding region binding to a human counterpart of the mouse antigen, and the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa.
[30] A method for selecting a target antigen suitable for treatment or prevention using a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa, the method comprising the following:
(a) obtaining a polypeptide comprising an antigen-binding region binding to a mouse antigen;
(b) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and an Fc variant according to any of [1] to [10] and [21] to [25];
(c) administering the polypeptide prepared in step (b) to a mouse model of a human disease; and
(d) when a therapeutic or preventive effect on the disease is observed in the mouse as a result of step (c), selecting a human counterpart of the mouse antigen as the target antigen suitable for treatment or prevention using a polypeptide comprising the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa.
[31] The method according to [30], wherein the method further comprises, in addition to steps (b) and (c):
(b′) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and the Fc region of naturally occurring IgG; and
(c′) administering the polypeptide prepared in step (b′) to a mouse model of a human disease, and step (d) is the step of
(d) when a stronger therapeutic or preventive effect on the disease is observed in the mouse that has received the polypeptide of step (b) than in the mouse that has received the polypeptide of step (b′) as a result of steps (c) and (c′), selecting a human counterpart of the mouse antigen as the target antigen suitable for treatment or prevention using a polypeptide comprising the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa.
[32] A method for selecting an antigen-binding region suitable for treatment or prevention using a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa, the method comprising the following:
(a) obtaining a plurality of polypeptides comprising antigen-binding regions binding to the same mouse antigen;
(b) preparing a polypeptide comprising each of the antigen-binding regions of the polypeptides obtained in step (a), and an Fc variant according to any of [1] to [10] and [21] to [25];
(c) administering the polypeptide prepared in step (b) to a mouse model of a human disease; and
(d) as a result of step (c), selecting the antigen-binding region of a polypeptide that exhibits a stronger therapeutic or preventive effect as the antigen-binding region suitable for treatment or prevention of the human disease using a polypeptide comprising the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa.
[33] A method for predicting safety or toxicity when a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa is administered to a human, the method comprising the following:
(a) obtaining a polypeptide comprising an antigen-binding region binding to a mouse antigen;
(b) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and an Fc variant according to any of [1] to [10] and [21] to [25];
(c) administering the polypeptide prepared in step (b) to a mouse; and
(d) analogically inferring the safety or toxicity, in a human, of a polypeptide comprising an antigen-binding region binding to a human counterpart of the mouse antigen, and the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa from the result(s) obtained in step (c) about the safety or toxicity of the polypeptide of step (b) in the mouse.
[34] A method for predicting pharmacokinetics when a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa is administered to a human, the method comprising the following:
(a) obtaining a polypeptide comprising an antigen-binding region binding to a mouse antigen;
(b) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and an Fc variant according to any of [1] to [10] and [21] to [25];
(c) administering the polypeptide prepared in step (b) to a mouse; and
(d) analogically inferring the pharmacokinetics, in a human, of a polypeptide comprising an antigen-binding region binding to a human counterpart of the mouse antigen, and the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa from the result(s) obtained in step (c) about the pharmacokinetics of the polypeptide of step (b) in the mouse.
[35] The method according to any of [26] to [32], wherein the disease is an immune inflammatory disease.
[36] The method according to [35], wherein the immune inflammatory disease is autoimmune disease.
[37] The method according to any of [26] to [36], wherein the mouse is a genetically modified mouse expressing the human antigen.
[38] The method according to any of [26] to [37], wherein the Fc region is the Fc region of IgG.
[39] The method according to any of [26] to [38], wherein the polypeptide is an antibody.
[40] A polypeptide comprising an antigen-binding region binding to a target antigen selected by a method according to [30] or [31], and an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa.
[41] A polypeptide comprising an antigen-binding region selected by a method according to [32], and an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa.
[42] The polypeptide according to [40] or [41], wherein the Fc region is the Fc region of IgG.
[43] The polypeptide according to any of [40] to [42], wherein the polypeptide is an antibody.
[44] A therapeutic or preventive agent for a human disease, comprising a polypeptide according to any of [40] to [43] as an active ingredient.

[0106] The present invention relates to an Fc variant selectively binding to mouse FcγRII relative to mouse FcγRIII.

[0107] The present invention provides a polypeptide which is a variant of a parent polypeptide comprising an Fc region, wherein the polypeptide comprises at least one amino acid alteration in the Fc region and has a ratio of [KD value for mouse FcγRIII]/[KD value for mouse FcγRII] of 6 or more. The present invention also provides a polypeptide which is a variant of a parent polypeptide comprising an Fc region, wherein the polypeptide comprises at least one amino acid alteration in the Fc region and the binding selectivity of the polypeptide for mouse FcγRII relative to mouse FcγRIII is improved by 5 times or more compared with that of the parent polypeptide.

[0108] Each polypeptide of the present invention can be prepared by the alteration of appropriate amino acid(s) in the Fc region of the parent polypeptide comprising an Fc region. The position, number, type, etc. of the amino acid alteration are not particularly limited. Any alteration may be acceptable as long as the polypeptide comprising the Fc variant produced by this alteration has the following property:

the ratio of [KD value for mouse FcγRIII]/[KD value for mouse FcγRII] is 6 or more; or the binding selectivity of the polypeptide for mouse FcγRII relative to mouse FcγRIII is improved by 5 times or more compared with that of the parent polypeptide.

[0109] The selectivity for mouse FcγRII and mouse FcγRIII can be indicated by the ratio between the binding activity against mouse FcγRII and the binding activity against mouse FcγRIII. The binding selectivity for mouse FcγRII relative to mouse FcγRIII is defined as a value determined by dividing [KD value for mouse FcγRIII] by [KD value for mouse FcγRII] (in the present specification, also referred to as I/A). In this case, a larger value thereof means higher selectivity for mouse FcγRII, whereas a smaller value thereof means lower selectivity for mouse FcγRII. I/A of the parent polypeptide and I/A of the altered polypeptide are each calculated. When I/A of the parent polypeptide is defined as 1, I/A of the altered polypeptide (in the present specification, also referred to as relative I/A) is determined. Relative I/A exceeding 1 means that the alteration has improved the selectivity for mouse FcγRII. Relative I/A below 1 means that the alteration has reduced the selectivity for mouse FcγRII.

[0110] In the polypeptide of the present invention, the ratio of [KD value for mouse FcγRIII]/[KD value for mouse FcγRII] is 6 or more, preferably 10 or more, 15 or more, 20 or more, 25 or more, or 30 or more, more preferably 35 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, or 90 or more. The binding selectivity of the polypeptide of the present invention for mouse FcγRII relative to mouse FcγRIII is improved by 5 times or more, preferably 10 times or more, 15 times or more, 20 times or more, 25 times or more, or 30 times or more, more preferably 35 times or more, 40 times or more, 50 times or more, 60 times or more, 70 times or more, 80 times or more, or 90 times or more, compared with that of the parent polypeptide.

[0111] One example of the preferred properties possessed by the polypeptide of the present invention can include the property of strongly binding to mouse FcγRII. Specifically, the polypeptide of the present invention preferably has the following property:

the KD value for mouse FcγRII is 20 nM or smaller; or

the binding activity of the polypeptide against mouse FcγRII is enhanced by 10 times or more compared with that of the parent polypeptide.

[0112] The KD value of the polypeptide of the present invention for mouse FcγRII is 20 nM or smaller, preferably 10 nM or smaller, 4 nM or smaller, or 2 nM or smaller, more preferably 1.5 nM or smaller, 1 nM or smaller, 0.7 nM or smaller, or 0.5 nM or smaller. Also, the binding activity of the polypeptide of the present invention against mouse FcγRII is enhanced by 10 times or more, preferably 20 times or more, 50 times or more, or 100 times or more, more preferably 150 times or more, 200 times or more, 300 times or more, or 400 times or more, compared with that of the parent polypeptide.

[0113] As mentioned later, an amount bound can also be used as an index instead of the KD value. Specifically, in the present specification, the binding activity against mouse FcγRII may be interchanged with an amount bound to mouse FcγRII, and the binding activity against mouse FcγRIII may be interchanged with an amount bound to mouse FcγRIII.

[0114] Examples of the amino acid alteration that can confer the property as mentioned above include the alteration of an amino acid at EU numbering position 230, the alteration of an amino acid at EU numbering position 231, the alteration of an amino acid at EU numbering position 232, the alteration of an amino acid at EU numbering position 238, the alteration of an amino acid at EU numbering position 239, the alteration of an amino acid at EU numbering position 240, the alteration of an amino acid at EU numbering position 241, the alteration of an amino acid at EU numbering position 266, the alteration of an amino acid at EU numbering position 267, the alteration of an amino acid at EU numbering position 268, the alteration of an amino acid at EU numbering position 271, the alteration of an amino acid at EU numbering position 295, the alteration of an amino acid at EU numbering position 296, the alteration of an amino acid at EU numbering position 298, the alteration of an amino acid at EU numbering position 324, the alteration of an amino acid at EU numbering position 326, the alteration of an amino acid at EU numbering position 327, the alteration of an amino acid at EU numbering position 330, the alteration of an amino acid at EU numbering position 331, the alteration of an amino acid at EU numbering position 333, the alteration of an amino acid at EU numbering position 334, the alteration of an amino acid at EU numbering position 335, and the alteration of an amino acid at EU numbering position 337. One of these amino acid alterations may be carried out, or two or more thereof may be combined.

[0115] Examples of a further preferred amino acid alteration include an alteration that substitutes an amino acid at EU numbering position 230 by Asp, Glu, Ile, Pro, Gln, or Val, an alteration that substitutes an amino acid at EU numbering position 231 by Ala, Asp, Glu, Ile, Leu, Met, Asn, Pro, Gln, Thr, or Trp, an alteration that substitutes an amino acid at EU numbering position 232 by Ala, Asp, Glu, Phe, Leu, Asn, Val, Trp, or Tyr, an alteration that substitutes an amino acid at EU numbering position 238 by Glu, Pro, or Gln, an alteration that substitutes an amino acid at EU numbering position 239 by Ala, Asp, Glu, Phe, Gly, His, Ile, Leu, Met, Asn, Pro, Gln, Arg, Thr, Val, Trp, or Tyr, an alteration that substitutes an amino acid at EU numbering position 240 by Glu, His, Gln, or Trp, an alteration that substitutes an amino acid at EU numbering position 241 by Trp or Tyr, an alteration that substitutes an amino acid at EU numbering position 266 by Leu, an alteration that substitutes an amino acid at EU numbering position 267 by Ala or Glu, an alteration that substitutes an amino acid at EU numbering position 268 by Asp, an alteration that substitutes an amino acid at EU numbering position 271 by Leu, an alteration that substitutes an amino acid at EU numbering position 295 by Leu, an alteration that substitutes an amino acid at EU numbering position 296 by Glu, Asn, Thr, or Trp, an alteration that substitutes an amino acid at EU numbering position 298 by Leu or Met, an alteration that substitutes an amino acid at EU numbering position 324 by Asp, Leu, or Met, an alteration that substitutes an amino acid at EU numbering position 326 by Asp, an alteration that substitutes an amino acid at EU numbering position 327 by Gly, an alteration that substitutes an amino acid at EU numbering position 330 by Gly, Lys, or Gln, an alteration that substitutes an amino acid at EU numbering position 331 by Asp, Phe, or Tyr, an alteration that substitutes an amino acid at EU numbering position 333 by Asn, Val, or Tyr, an alteration that substitutes an amino acid at EU numbering position 334 by Arg, an alteration that substitutes an amino acid at EU numbering position 335 by Asn or Tyr, and an alteration that substitutes an amino acid at EU numbering position 337 by Ile, Lys, or Trp. One of these alterations may be carried out, or two or more thereof may be combined.

Preferred examples of such alterations include alterations described in Tables 2 to 17, 24, and 25.

[0116] The present invention encompasses a polypeptide which is a variant of a parent polypeptide comprising a mouse Fc region, wherein the polypeptide comprises particular amino acid alteration(s) in the Fc region. Examples of such amino acid alterations include an alteration that substitutes an amino acid at position 230 by Asp, Glu, Ile, Pro, Gln, or Val, an alteration that substitutes an amino acid at position 231 by Ala, Asp, Glu, Ile, Leu, Met, Asn, Pro, Gln, Thr, or Trp, an alteration that substitutes an amino acid at position 232 by Ala, Asp, Glu, Phe, Leu, Asn, Val, Trp, or Tyr, an alteration that substitutes an amino acid at position 238 by Glu, Pro, or Gln, an alteration that substitutes an amino acid at position 239 by Ala, Phe, Gly, His, Ile, Leu, Met, Asn, Pro, Gln, Arg, Thr, Val, Trp, or Tyr, an alteration that substitutes an amino acid at position 240 by Glu, His, Gln, or Trp, an alteration that substitutes an amino acid at position 241 by Trp or Tyr, an alteration that substitutes an amino acid at position 266 by Leu, an alteration that substitutes an amino acid at position 267 by Glu, an alteration that substitutes an amino acid at position 268 by Asp, an alteration that substitutes an amino acid at position 271 by Leu, an alteration that substitutes an amino acid at position 295 by Leu, an alteration that substitutes an amino acid at position 296 by Glu, Asn, Thr, or Trp, an alteration that substitutes an amino acid at position 298 by Leu or Met, an alteration that substitutes an amino acid at position 324 by Asp, Leu, or Met, an alteration that substitutes an amino acid at position 326 by Asp, an alteration that substitutes an amino acid at position 327 by Gly, an alteration that substitutes an amino acid at position 330 by Gly, Lys, or Gln, an alteration that substitutes an amino acid at position 331 by Asp, Phe, or Tyr, an alteration that substitutes an amino acid at position 333 by Asn, Val, or Tyr, an alteration that substitutes an amino acid at position 334 by Arg, an alteration that substitutes an amino acid at position 335 by Asn or Tyr, and an alteration that substitutes an amino acid at position 337 by Ile, Lys, or Trp (wherein all positions are indicated by EU numbering). One of these alterations may be carried out, or two or more thereof may be combined.

[0117] The polypeptide may further comprise different amino acid alteration(s) in addition to these amino acid alterations. Such amino acid alteration(s) is preferably, for example, an alteration that substitutes an amino acid at EU numbering position 239 by Asp or Glu and/or an alteration that substitutes an amino acid at EU numbering position 267 by Ala. One of these alterations may be carried out, or two or more thereof may be combined. Preferred examples of such alterations include alterations described in Tables 2 to 17, 24, and 25. The resulting polypeptides are useful in terms of having the feature to selectively bind to mouse FcγRII relative to mouse FcγRIII.

[0118] Another example of the preferred properties of the polypeptide of the present invention can include the property of weakly binding to mouse FcγRIII. Specifically, the polypeptide of the present invention preferably has the following property:

the KD value for mouse FcγRIII is 1 μM or larger; or

the binding activity of the polypeptide against mouse FcγRIII is reduced to 0.25 times or less that of the parent polypeptide.

[0119] The KD value of the polypeptide of the present invention for mouse FcγRIII is 1 μM or larger, preferably 1.2 μM or larger, 1.5 μM or larger, or 2 μM or larger, more preferably 2.5 μM or larger, 3 μM or larger, 4 μM or larger, or 5 μM or larger. Also, the binding activity of the polypeptide of the present invention against mouse FcγRIII is reduced to 0.25 times or less, preferably 0.20 times or less, 0.18 times or less, 0.16 times or less, or 0.14 times or less, more preferably 0.12 times or less, 0.10 times or less, 0.08 times or less, or 0.06 times or less that of the parent polypeptide.

[0120] As mentioned later, an amount bound can also be used as an index instead of the KD value. Specifically, in the present specification, the binding activity against mouse FcγRII may be interchanged with an amount bound to mouse FcγRII, and the binding activity against mouse FcγRIII may be interchanged with an amount bound to mouse FcγRIII.

[0121] Examples of the amino acid alteration that can confer the property as mentioned above include the alteration of an amino acid at EU numbering position 230, the alteration of an amino acid at EU numbering position 231, the alteration of an amino acid at EU numbering position 232, the alteration of an amino acid at EU numbering position 237, the alteration of an amino acid at EU numbering position 238, the alteration of an amino acid at EU numbering position 239, the alteration of an amino acid at EU numbering position 241, the alteration of an amino acid at EU numbering position 267, and the alteration of an amino acid at EU numbering position 298. One of these amino acid alterations may be carried out, or two or more thereof may be combined.

[0122] Examples of a further preferred amino acid alteration include an alteration that substitutes an amino acid at EU numbering position 230 by Glu, Ile, or Gln, an alteration that substitutes an amino acid at EU numbering position 231 by Ala, Asp, Asn, Pro, or Thr, an alteration that substitutes an amino acid at EU numbering position 232 by Ala, Lys, Asn, or Tyr, an alteration that substitutes an amino acid at EU numbering position 237 by Glu, an alteration that substitutes an amino acid at EU numbering position 238 by Asp or Glu, an alteration that substitutes an amino acid at EU numbering position 239 by Asp, Glu, Phe, Lys, Leu, Asn, Trp, or Tyr, an alteration that substitutes an amino acid at EU numbering position 241 by Asp, Glu, or Thr, an alteration that substitutes an amino acid at EU numbering position 267 by Met, and an alteration that substitutes an amino acid at EU numbering position 298 by His. One of these alterations may be carried out, or two or more thereof may be combined. Preferred examples of such alterations include alterations described in Tables 18 to 23, 26, and 27.

[0123] The present invention encompasses a polypeptide which is a variant of a parent polypeptide comprising a mouse Fc region, wherein the polypeptide comprises particular amino acid alteration(s) in the Fc region. Examples of such amino acid alterations include an alteration that substitutes an amino acid at position 230 by Glu, Ile, or Gln, an alteration that substitutes an amino acid at position 231 by Ala, Asp, Asn, Pro, or Thr, an alteration that substitutes an amino acid at position 232 by Ala, Lys, Asn, or Tyr, an alteration that substitutes an amino acid at position 237 by Glu, an alteration that substitutes an amino acid at position 238 by Asp or Glu, an alteration that substitutes an amino acid at position 239 by Phe, Lys, Leu, Asn, Trp, or Tyr, an alteration that substitutes an amino acid at position 241 by Asp, Glu, or Thr, an alteration that substitutes an amino acid at position 266 by Leu, an alteration that substitutes an amino acid at position 267 by Met, and an alteration that substitutes an amino acid at position 298 by His (wherein all positions are indicated by EU numbering). One of these alterations may be carried out, or two or more thereof may be combined.

[0124] The polypeptide may further comprise different amino acid alteration(s) in addition to these amino acid alterations. Such amino acid alteration(s) is preferably, for example, an alteration that substitutes an amino acid at EU numbering position 239 by Asp or Glu. One of these alterations may be carried out, or two or more thereof may be combined. Preferred examples of such alterations include alterations described in Tables 18 to 23, 26, and 27. The resulting polypeptides are useful in terms of having the feature to selectively bind to mouse FcγRII relative to mouse FcγRIII.

[0125] A further example of the preferred properties of the polypeptide of the present invention can include the property of binding to mouse FcγRII with strength equivalent to or higher than that of the parent polypeptide and binding to mouse FcγRIII more weakly compared with the parent polypeptide. Specifically, the polypeptide of the present invention preferably has the following property:

the KD value for mouse FcγRII is 400 nM or smaller, and the KD value for mouse FcγRIII is 1 μM or larger; or

the binding activity of the polypeptide against mouse FcγRII is 0.5 times or more that of the parent polypeptide, and the binding activity of the polypeptide against mouse FcγRIII is 0.25 times or less that of the parent polypeptide.

[0126] The KD value of the polypeptide of the present invention for mouse FcγRII is 400 nM or smaller, preferably 360 nM or smaller, 320 nM or smaller, or 280 nM or smaller, more preferably 250 nM or smaller, 200 nM or smaller, 150 nM or smaller, or 100 nM or smaller, and the KD value of the polypeptide of the present invention for mouse FcγRIII is 1 μM or larger, preferably 1.2 μM or larger, 1.5 μM or larger, or 2 μM or larger, more preferably 2.5 μM or larger, 3 μM or larger, 4 μM or larger, or 5 μM or larger. Also, the binding activity of the polypeptide of the present invention against mouse FcγRII is 0.5 times or more, preferably 0.6 times or more, 0.75 times or more, or 1.0 times or more, more preferably 1.5 times or more, 2 times or more, 2.5 times or more, or 3 times or more that of the parent polypeptide, and the binding activity of the polypeptide of the present invention against mouse FcγRIII is 0.25 times or less, preferably 0.20 times or less, 0.18 times or less, 0.16 times or less, or 0.14 times or less, more preferably 0.12 times or less, 0.10 times or less, 0.08 times or less, or 0.06 times or less that of the parent polypeptide.

[0127] As mentioned later, an amount bound can also be used as an index instead of the KD value. Specifically, in the present specification, the binding activity against mouse FcγRII may be interchanged with an amount bound to mouse FcγRII, and the binding activity against mouse FcγRIII may be interchanged with an amount bound to mouse FcγRIII.

[0128] The polypeptide according to the present invention refers to a peptide having a plurality of amino acids, or a protein. The polypeptide may be a polypeptide consisting of an organism-derived sequence or may be a polypeptide consisting of an artificially designed sequence. Alternatively, a natural polypeptide, a synthetic polypeptide, a recombinant polypeptide, or the like may be used.

[0129] The Fcγ receptor (in the present specification, also referred to as an Fcγ receptor, FcγR, or FcgR) refers to a receptor capable of binding to the Fc region of an IgG subclass monoclonal antibody and means any member of the protein family substantially encoded by Fcγ receptor genes. The human Fcγ receptor refers to a receptor capable of binding to the Fc region of a human IgG1, IgG2, IgG3, or IgG4 monoclonal antibody. This family includes, but not limited to: FcγRI (CD64) including isoforms FcγRIa, FcγRIb, and FcγRIc; FcγRII (CD32) including isoforms FcγRIIa (including allotypes H131 (H type) and R131 (R type)), FcγRIIb (including FcγRIIb-1 and FcγRIIb-2), and FcγRIIc; and FcγRIII (CD16) including isoforms FcγRIIIa (including allotypes V158 and F158) and FcγRIIIb (including allotypes FcγRIIIb-NA1 and FcγRIIIb-NA2); and any yet-to-be-discovered human FcγR member or FcγR isoform or allotype. Preferred examples of the human Fcγ receptor include human FcγRI (CD64), FcγRIIA (CD32), FcγRIIB (CD32), FcγRIIIA (CD16), and FcγRIIIB (CD16). The mouse FcγR refers to a receptor capable of binding to the Fc region of a mouse IgG1, IgG2a, IgG2b, or IgG3 monoclonal antibody and means any member of the protein family substantially encoded by Fcγ receptor genes. The mouse FcγR family includes, but not limited to, FcγRI (CD64), FcγRII (CD32), FcγRIII (CD16), and FcγRIII-2 (CD16-2 or FcγRIV), and any yet-to-be-discovered mouse FcγR member or FcγR isoform or allotype. Preferred examples of the mouse Fcγ receptor include mouse FcγRI (CD64), FcγRII (CD32), FcγRIII (CD16), and FcγRIII-2 (CD16-2 or FcγRIV). The FcγR includes those derived from humans, mice, rats, rabbits, and monkeys. The FcγR is not limited to them and may be derived from any organism.

[0130] The polynucleotide sequence and amino acid sequence of human FcγRI are described in SEQ ID NOs: 10 (NM_000566.3) and 11 (NP_000557.1), respectively;

the polynucleotide sequence and amino acid sequence of human FcγRIIA are described in SEQ ID NOs: 12 (BC020823.1) and 13 (AAH20823.1), respectively;

the polynucleotide sequence and amino acid sequence of human FcγRIIB are described in SEQ ID NOs: 14 (BC146678.1) and 15 (AAI46679.1), respectively;

the polynucleotide sequence and amino acid sequence of human FcγRIIIA are described in SEQ ID NOs: 16 (BC033678.1) and 17 (AAH33678.1), respectively; and

the polynucleotide sequence and amino acid sequence of human FcγRIIIB are described in SEQ ID NOs: 18 (BC128562.1) and 19 (AAI28563.1), respectively (RefSeq registration numbers are shown in parentheses).

[0131] Human FcγRIIa has two types of gene polymorphisms that substitute the 131st amino acid of FcγRIIa by histidine (H type) or arginine (R type) (J Exp Med, 172, 19-25, 1990).

[0132] FcγRIIb1 and FcγRIIb2 have been reported as splicing variants of human FcγRIIb. In addition, a splicing variant called FcγRIIb3 has also been reported (J. Exp. Med, 1989, 170: 1369). The human FcγRIIb includes, in addition to these splicing variants, all of splicing variants registered in NCBI under NP_001002273.1, NP_001002274.1, NP_001002275.1, NP_001177757.1, and NP_003992.3. Also, the human FcγRIIb includes every previously reported gene polymorphism and also includes FcγRIIb (Arthritis Rheum, 2003, 48: 3242-52; Hum Mol Genet, 2005, 14: 2881-92; and Arthritis Rheum. 2002 May; 46 (5): 1242-54) and every gene polymorphism that may be reported in the future.

[0133] The polynucleotide sequence and amino acid sequence of mouse FcγRI are described in SEQ ID NOs: 33 (NM_010186.5) and 20 (NP_034316.1), respectively;

the polynucleotide sequence and amino acid sequence of mouse FcγRII are described in SEQ ID NOs: 34 (NM_010187.2) and 21 (NP_034317.1), respectively;

the polynucleotide sequence and amino acid sequence of mouse FcγRIII are described in SEQ ID NOs: 35 (NM_010188.5) and 22 (NP_034318.2), respectively; and

the polynucleotide sequence and amino acid sequence of mouse FcγRIV are described in SEQ ID NOs: 36 (NM_144559.2) and 23 (NP_653142.2), respectively

(NCBI Reference Sequence registration numbers are shown in parentheses).

[0134] FcγRIIb1 and FcγRIIb2 have been reported as splicing variants of mouse FcγRII and registered under GenBank accession Nos. M16367 and X04648, respectively. Other splicing variants have been reported in J. Immunol, 1996, 157: 189 and J. Immunol, 1996, 157: 4707. These splicing variants are also included in the mouse FcγRII. The mouse FcγRII includes every previously reported gene polymorphism and also includes every gene polymorphism that may be reported in the future.

[0135] As also shown later in Examples, mouse FcγR having the highest sequence identity to mouse FcγRII is mouse FcγRIII (sequence identity of their extracellular regions: 93%). Mouse IgG1 exhibits binding only to mouse FcγRII and FcγRIII among 4 types of mouse Fcγ receptors, without binding to mouse FcγRI and FcγRIV (Science, 310, 1510-1512, 2005). From such viewpoints, desirably, the Fc variant selectively binding to mouse FcγRII has higher binding activity against FcγRII and lower binding activity against FcγRIII than those of the Fc region of naturally occurring IgG. In the present specification, the Fc variant selectively binding to mouse FcγRII relative to mouse FcγRIII means an Fc region in which a value of the Fc region determined by dividing [KD value for mouse FcγRIII] by [KD value for mouse FcγRII] is larger than a value of the Fc region of naturally occurring mouse IgG determined by dividing [KD value for mouse FcγRIII] by [KD value for mouse FcγRII].

[0136] The naturally occurring IgG means a polypeptide that contains an amino acid sequence identical to that of IgG found in nature and belongs to a class of an antibody substantially encoded by an immunoglobulin gamma gene. For example, the naturally occurring mouse IgG means naturally occurring mouse IgG1, naturally occurring mouse IgG2a, naturally occurring mouse IgG2b, naturally occurring mouse IgG3, or the like. The naturally occurring human IgG means naturally occurring human IgG1, naturally occurring human IgG2, naturally occurring human IgG3, naturally occurring human IgG4, or the like. The naturally occurring IgG also includes variants or the like spontaneously derived therefrom.

[0137] The heavy chain constant region of naturally occurring IgG means a heavy chain constant region containing an amino acid sequence identical to that of a heavy chain constant region originated from IgG found in nature. For example, the heavy chain constant region originated from naturally occurring mouse IgG means a heavy chain constant region originated from naturally occurring mouse IgG1, a heavy chain constant region originated from naturally occurring mouse IgG2a, a heavy chain constant region originated from naturally occurring mouse IgG2b, or a heavy chain constant region originated from naturally occurring mouse IgG3. The heavy chain constant region originated from naturally occurring human IgG means a heavy chain constant region originated from naturally occurring human IgG1, a heavy chain constant region originated from naturally occurring human IgG2, a heavy chain constant region originated from naturally occurring human IgG3, or a heavy chain constant region originated from naturally occurring human IgG4. The heavy chain constant region of naturally occurring IgG also includes variants or the like spontaneously derived therefrom. The heavy chain constant region of naturally occurring mouse IgG is shown in FIGS. 11-1 to 11-4 (SEQ ID NOs: 24 to 27), and the heavy chain constant region of naturally occurring human IgG is shown in FIG. 12 (SEQ ID NOs: 28 to 31). The heavy chain constant region of naturally occurring IgG also includes every previously reported gene polymorphism and every gene polymorphism that may be reported in the future. For example, a heavy chain constant region consisting of the amino acid sequence represented by SEQ ID NO: 24 is known as the heavy chain constant region of naturally occurring mouse IgG1. The naturally occurring mouse IgG1 also includes all of gene polymorphisms registered under, for example, GenBank accession Nos. J00453 and J35252. In the present invention, amino acid residues at main positions to be altered are common among all of these gene polymorphisms. The present invention is therefore effective even for these gene polymorphisms.

[0138] The Fc region refers to a region comprising hinges or a portion thereof and CH2 and CH3 domains in an antibody molecule. The Fc region of IgG class means, but not limited to, a region from, for example, cysteine 226 (EU numbering (in the present specification, also referred to as EU INDEX)) (see FIGS. 11-1 to 11-4 and FIG. 12) to the C terminus or from proline 230 (EU numbering) to the C terminus.

[0139] The Fc region of naturally occurring IgG means an Fc region containing an amino acid sequence identical to that of an Fc region originated from IgG found in nature. For example, the Fc region originated from naturally occurring mouse IgG means an Fc region originated from naturally occurring mouse IgG1, an Fc region originated from naturally occurring mouse IgG2a, an Fc region originated from naturally occurring mouse IgG2b, or an Fc region originated from naturally occurring mouse IgG3. The Fc region originated from naturally occurring human IgG means an Fc region originated from naturally occurring human IgG1, an Fc region originated from naturally occurring human IgG2, an Fc region originated from naturally occurring human IgG3, or an Fc region originated from naturally occurring human IgG4. The Fc region of naturally occurring IgG also includes variants or the like spontaneously derived therefrom. The Fc region of naturally occurring mouse IgG is shown as a partial sequence of FIGS. 11-1 to 11-4 (SEQ ID NOs: 24 to 27), and the Fc region of naturally occurring human IgG is shown as a partial sequence of FIG. 12 (SEQ ID NOs: 28 to 31).

[0140] The Fc region can be preferably obtained by the partial digestion of, for example, an IgG monoclonal antibody with a proteolytic enzyme such as pepsin followed by re-elution of a fraction adsorbed on a protein A or protein G column. Such a proteolytic enzyme is not particularly limited as long as the enzyme is capable of digesting a whole antibody to restrictively form Fab or F(ab′)2 under appropriately set reaction conditions (e.g., pH) of the enzyme. Examples thereof can include pepsin and papain.

[0141] In the present specification, the “parent polypeptide” means a polypeptide that forms the basis for the preparation of the polypeptide of the present invention. Specifically, the parent polypeptide means a polypeptide comprising an Fc region before addition of amino acid alteration(s) to the Fc region. An exemplary parent polypeptide according to the present invention is preferably a polypeptide comprising the Fc region of an antibody (IgA, IgD, IgE, IgG, or IgM), particularly, IgG, more preferably a polypeptide comprising the Fc region of mouse or human IgG, particularly preferably a polypeptide comprising the Fc region of mouse IgG1. The parent polypeptide may be a polypeptide comprising the Fc region of naturally occurring IgG or may be a polypeptide comprising an Fc variant derived from the Fc region of naturally occurring IgG by the addition of alteration(s) other than the amino acid alteration of the present invention.

[0142] The Fc region of the present invention is not limited as long as the Fc region is of an antibody (IgA, IgD, IgE, IgG, or IgM), particularly, IgG. The Fc region of the present invention is preferably the Fc region of mouse IgG (IgG1, IgG2a, IgG2b, or IgG3) or human IgG (IgG1, IgG2, IgG3, or IgG4), more preferably the Fc region of mouse IgG1. The amino acid sequences of the mouse and human IgG Fc regions are known in the art as shown in FIGS. 11-1 to 11-4 (SEQ ID NOs: 24 to 27) and FIG. 12 (SEQ ID NOs: 28 to 31).

[0143] The polypeptide of the present invention is not particularly limited as long as the polypeptide comprises the Fc region. Preferably, the polypeptide of the present invention comprises an antigen-binding region (variable regions, Fab, F(ab′)2, Fv, CDRs, etc.) and the Fc region. The polypeptide of the present invention is particularly preferably an antibody (IgA, IgD, IgE, IgG, or IgM). Preferred examples of the antibody can include IgG, particularly, mouse IgG (IgG1, IgG2a, IgG2b, or IgG3) and human IgG (IgG1, IgG2, IgG3, or IgG4). The antibody is more preferably mouse IgG1. The amino acid sequences of the mouse and human IgG heavy chain constant regions are known in the art as shown in FIGS. 11-1 to 11-4 (SEQ ID NOs: 24 to 27) and FIG. 12 (SEQ ID NOs: 28 to 31).

[0144] Alternatively, the polypeptide of the present invention is preferably an Fc fusion protein. Examples of the protein to be fused include, but not limited to, biologically active peptides, adhesion molecules, ligands/receptors, and enzymes. Specific examples thereof include: receptor extracellular regions such as TNFR, IL1R, VEGFR, and CTLA4 (Nat Med 2003, 9 (1), 47-52; and BioDrugs 2006, 20 (3), 151-60); antibody-like molecules such as scFv (WO2005/037989), single-domain antibodies (WO2004/058821 and WO2003/002609), DARPins (WO2002/020565), Affibody (WO1995/001937), Avimer (WO2004/044011 and WO2005/040229), and Adnectin (WO2002/032925) (Current Opinion in Biotechnology 2006, 17, 653-658; Current Opinion in Biotechnology 2007, 18, 1-10; Current Opinion in Structural Biology 1997, 7, 463-469; and Protein Science 2006, 15, 14-27); and self-antigens recognized by autoantibodies, such as acetylcholine receptor, desmoglein 1, desmoglein 3, double-stranded DNA, histidine-tRNA ligase, ribonucleoprotein, snRNP core protein, Ro/SS-A, La/SS-B, centromere, Ri, topoisomerase-1, histone, nucleoporin 62, Sp100 nuclear antigen, nucleoporin 210 kDa, ganglioside GQ1B, ganglioside GD3, ganglioside GM1, actin, thrombin, phospholipid, neutrophil cytoplasmic antigen, neutrophil perinuclear antigen, intracellular enzyme, smooth muscle cell membrane antigen, mitochondria, muscle-specific kinase (MUSK), voltage-gated calcium channel (P/Q-type), iodide peroxidase (microsomal), TSH receptor, Hu, cerebellar Purkinje cells, aminophylline, voltage-gated potassium channel (VGKC), basal ganglion, N-methyl-D-aspartate receptor (NMDA), glutamate decarboxylase (GAD65), amphiphysin, and aquaporin-4. The polypeptide of the present invention may bind to one type of target molecule or epitope as with general antibodies or may bind to plural types of target molecules or epitopes as with multispecific antibodies.

[0145] Amino acid substitution for improving binding activity against FcRn (J Immunol 2006 January 1; 176 (1), 346-356; J Biol Chem 2006 Aug. 18; 281(33), 23514-23524; Int Immunol 2006 December; 18 (12), 1759-1769; Nat Biotechnol 2010 February; 28 (2), 157-159; WO2006/019447, WO2006/053301, and WO2009/086320) or amino acid substitution for improving antibody heterogeneity or stability (WO2009/041613) may be added to the polypeptide of the present invention. Alternatively, amino acid substitution for promoting the disappearance of an antigen (WO2011/122011 and PCT/JP2011/072550) or amino acid substitution for allowing the polypeptide of the present invention to repetitively bind to a plurality of antigen molecules (WO2009/125825 and PCT/JP2011/077619) may be added to the polypeptide of the present invention.

[0146] The type of the amino acid alteration according to the present invention can be, for example, any of amino acid substitution, deletion, addition, insertion, and modification or a combination thereof and is preferably amino acid substitution.

[0147] In the present invention, the term “antibody” is used in the broadest sense and includes any antibody such as monoclonal antibodies (including whole monoclonal antibodies), polyclonal antibodies, antibody variants, antibody fragments, multispecific antibodies (e.g., bispecific antibodies), chimeric antibodies, and humanized antibodies as long as the antibody exhibits the desired biological activity.

[0148] The antibody of the present invention is not limited by the type of its antigen, an animal of its origin, etc. and can be any antibody. Examples of the origin of the antibody can include, but not particularly limited to, human antibodies, mouse antibodies, rat antibodies, rabbit antibodies, and monkey antibodies. The antibody of the present invention is preferably a mouse or human antibody, more preferably a mouse antibody.

[0149] The antibody can be prepared by a method well known to those skilled in the art. For example, the monoclonal antibodies may be produced by a hybridoma method (Kohler and Milstein, Nature 256, 495 (1975)) or a recombination method (U.S. Pat. No. 4,816,567). Alternatively, the monoclonal antibodies may be isolated from phage-displayed antibody libraries (Clackson et al, Nature 352, 624-628 (1991); and Marks et al, J Mol Biol 222, 581-597 (1991)).

[0150] The humanized antibodies are also called reshaped human antibodies. Specifically, for example, a humanized antibody consisting of a nonhuman animal (e.g., mouse) antibody CDR-grafted human antibody is known in the art. General gene recombination approaches are also known for obtaining the humanized antibodies. Specifically, for example, overlap extension PCR is known in the art as a method for grafting mouse antibody CDRs to human FRs.

[0151] A DNA encoding an antibody variable region comprising three CDRs and four FRs linked and a human antibody constant region-encoding DNA can be inserted into expression vectors such that these DNAs are fused in frame to prepare vectors for humanized antibody expression. These vectors having the inserts are transferred to hosts to establish recombinant cells. Then, the recombinant cells are cultured for the expression of the humanized antibody-encoding DNA to produce the humanized antibodies into the cultures of the cultured cells (see European Patent Publication No. EP 239400 and International Publication No. WO1996/002576).

[0152] If necessary, FR amino acid residue(s) may be substituted such that the CDRs of the reshaped human antibody form an appropriate antigen-binding site. For example, the amino acid sequence of FR can be mutated by the application of the PCR method used in the mouse CDR grafting to the human FRs.

[0153] The desired human antibody can be obtained by DNA immunization using transgenic animals having all repertoires of human antibody genes (see International Publication Nos. WO1993/012227, WO1992/003918, WO1994/002602, WO1994/025585, WO1996/034096, and WO1996/033735) as immunized animals.

[0154] In addition, a technology of obtaining human antibodies by panning using human antibody libraries is also known. For example, human antibody variable regions are expressed as a single-chain antibody (scFv) on the surface of phages by a phage display method. A phage expressing antigen-binding scFv can be selected. The gene of the selected phage can be analyzed to determine DNA sequences encoding the variable regions of the antigen-binding human antibody. After the determination of the DNA sequence of the antigen-binding scFv, the variable region sequences can be fused in frame with the sequences of the desired human antibody constant regions and then inserted to appropriate expression vectors to prepare expression vectors. The expression vectors are transferred to the preferred expression cells as exemplified above. The human antibody-encoding genes are expressed by the cells to obtain the human antibodies. These methods are already known in the art (see International Publication Nos. WO1992/001047, WO1992/020791, WO1993/006213, WO1993/011236, WO1993/019172, WO1995/001438, and WO1995/015388).

[0155] The variable regions constituting the antibody of the present invention can be variable regions that recognize an arbitrary antigen.

[0156] In the present specification, the antigen is not particularly limited and can be any antigen. Examples of the antigen preferably include ligands (cytokines, chemokines, etc.), receptors, cancer antigens, MHC antigens, differentiation antigens, immunoglobulins, and immune complexes partially comprising immunoglobulins.

[0157] Examples of the cytokines can include interleukins 1 to 18, colony-stimulating factors (G-CSF, M-CSF, GM-CSF, etc.), interferons (IFN-α, IFN-β, IFN-γ, etc.), growth factors (EGF, FGF, IGF, NGF, PDGF, TGF, HGF, etc.), tumor necrosis factors (TNF-α and TNF-β), lymphotoxin, erythropoietin, leptin, SCF, TPO, MCAF, and BMP.

[0158] Examples of the chemokines can include: CC chemokines such as CCL1 to CCL28; CXC chemokines such as CXCL1 to CXCL17; C chemokines such as XCL1 to XCL2; and CX3C chemokines such as CX3CL1.

[0159] Examples of the receptors can include receptors belonging to receptor families such as hematopoietic growth factor receptor family, cytokine receptor family, tyrosine kinase receptor family, serine/threonine kinase receptor family, TNF receptor family, G protein-coupled receptor family, GPI-anchored receptor family, tyrosine phosphatase receptor family, adhesion factor family, and hormone receptor family. These receptors belonging to the receptor families and their features are described in many literatures, for example, Cooke B A, King R J B, van der Molen H J ed. New Comprehensive Biochemistry Vol 18B “Hormones and their Actions Part II” pp. 1-46 (1988) Elsevier Science Publishers BV, Patthy (Cell (1990) 61 (1), 13-14), Ullrich et al. (Cell (1990) 61 (2), 203-212), Massague (e with acute accent) (Cell (1992) 69 (6), 1067-1070), Miyajima et al. (Annu Rev Immunol (1992) 10, 295-331), Taga et al. (FASEB J (1992) 6, 3387-3396), Fantl et al. (Annu Rev Biochem (1993), 62, 453-481), Smith et al. (Cell (1994) 76 (6), 959-962), and Flower DR (Biochim Biophys Acta (1999) 1422 (3), 207-234).

[0160] Specific examples of the receptors belonging to the receptor families mentioned above preferably include human or mouse erythropoietin (EPO) receptors (Blood (1990) 76 (1), 31-35; and Cell (1989) 57 (2), 277-285), human or mouse granulocyte colony-stimulating factor (G-CSF) receptors (Proc Natl Acad Sci USA (1990) 87 (22), 8702-8706; and mG-CSFR, Cell (1990) 61 (2), 341-350), human or mouse thrombopoietin (TPO) receptors (Proc Natl Acad Sci USA (1992) 89 (12), 5640-5644; and EMBO J (1993) 12 (7), 2645-53), human or mouse insulin receptors (Nature (1985) 313 (6005), 756-761), human or mouse Flt-3 ligand receptors (Proc Natl Acad Sci USA (1994) 91 (2), 459-463), human or mouse platelet-derived growth factor (PDGF) receptors (Proc Natl Acad Sci USA (1988) 85 (10), 3435-3439), human or mouse interferon (IFN)-α and -β receptors (Cell (1990) 60 (2), 225-234; and Cell (1994) 77 (3), 391-400), human or mouse leptin receptors, human or mouse growth hormone (GH) receptors, human or mouse interleukin (IL)-10 receptors, human or mouse insulin-like growth factor (IGF)-I receptors, human or mouse leukemic inhibitory factor (LIF) receptors, and human or mouse ciliary neurotrophic factor (CNTF) receptors.

[0161] The cancer antigens refer to antigens that are expressed in conjunction with the malignant transformation of cells and are also called tumor-specific antigens. Abnormal sugar chains that appear on cell surface or protein molecules during the malignant transformation of cells are also cancer antigens and are also called cancer carbohydrate antigens. Examples of the cancer antigens preferably include GPC3 (Int J Cancer (2003) 103 (4), 455-65) which belongs to the GPI-anchored receptor family as one of the receptors mentioned above and is expressed in some cancers including liver cancer, EpCAM (Proc Natl Acad Sci USA (1989) 86 (1), 27-31) which is expressed in a plurality of cancers including lung cancer, CA19-9, CA15-3, and sialyl SSEA-1 (SLX).

[0162] The MHC antigens are classified mainly into MHC class I antigens and MHC class II antigens. The MHC class I antigens include HLA-A, -B, -C, -E, -F, -G, and -H. The MHC class II antigens include HLA-DR, -DQ, and -DP.

[0163] The differentiation antigens can include CD1, CD2, CD4, CD5, CD6, CD7, CD8, CD10, CD11a, CD11b, CD11c, CD13, CD14, CD15s, CD16, CD18, CD19, CD20, CD21, CD23, CD25, CD28, CD29, CD30, CD32, CD33, CD34, CD35, CD38, CD40, CD41a, CD41b, CD42a, CD42b, CD43, CD44, CD45, CD45RO, CD48, CD49a, CD49b, CD49c, CD49d, CD49e, CD49f, CD51, CD54, CD55, CD56, CD57, CD58, CD61, CD62E, CD62L, CD62P, CD64, CD69, CD71, CD73, CD95, CD102, CD106, CD122, CD126, and CDw130.

[0164] The immunoglobulins include IgA, IgM, IgD, IgG, and IgE. The immune complexes comprise at least any component of the immunoglobulins.

[0165] Other examples of the antigen can include the following molecules: 17-IA, 4-1BB, 4Dc, 6-keto-PGF1a, 8-iso-PGF2a, 8-oxo-dG, A1 adenosine receptor, A33, ACE, ACE-2, activin, activin A, activin AB, activin B, activin C, activin RIA, activin RIA ALK-2, activin RIB ALK-4, activin RIIA, activin RIIB, ADAM, ADAM10, ADAM12, ADAM15, ADAM17/TACE, ADAM8, ADAM9, ADAMTS, ADAMTS4, ADAMTS5, addressin, aFGF, ALCAM, ALK, ALK-1, ALK-7, alpha-1-antitrypsin, alpha-V/beta-1 antagonist, ANG, Ang, APAF-1, APE, APJ, APP, APRIL, AR, ARC, ART, artemin, anti-Id, ASPARTIC, atrial natriuretic factor, av/b3 integrin, Axl, b2M, B7-1, B7-2, B7-H, B-lymphocyte stimulator (BlyS), BACE, BACE-1, Bad, BAFF, BAFF-R, Bag-1, BAK, Bax, BCA-1, BCAM, Bcl, BCMA, BDNF, b-ECGF, bFGF, BID, Bik, BIM, BLC, BL-CAM, BLK, BMP, BMP-2 BMP-2a, BMP-3 osteogenin, BMP-4, BMP-2b, BMP-5, BMP-6 Vgr-1, BMP-7 (OP-1), BMP-8 (BMP-8a, OP-2), BMPR, BMPR-IA (ALK-3), BMPR-IB (ALK-6), BRK-2, RPK-1, BMPR-II (BRK-3), BMP, b-NGF, BOK, bombesin, bone-derived neurotrophic factor, BPDE, BPDE-DNA, BTC, complement factor 3 (C3), C3a, C4, C5, C5a, C10, CA125, CAD-8, calcitonin, cAMP, carcinoembryonic antigen (CEA), carcinoma-associated antigen, cathepsin A, cathepsin B, cathepsin C/DPPI, cathepsin D, cathepsin E, cathepsin H, cathepsin L, cathepsin 0, cathepsin S, cathepsin V, cathepsin X/Z/P, CBL, CCI, CCK2, CCL, CCL1, CCL11, CCL12, CCL13, CCL14, CCL15, CCL16, CCL17, CCL18, CCL19, CCL2, CCL20, CCL21, CCL22, CCL23, CCL24, CCL25, CCL26, CCL27, CCL28, CCL3, CCL4, CCL5, CCL6, CCL7, CCL8, CCL9/10, CCR, CCR1, CCR10, CCR10, CCR2, CCR3, CCR4, CCR5, CCR6, CCR7, CCR8, CCR9, CD1, CD2, CD3, CD3E, CD4, CD5, CD6, CD7, CD8, CD10, CD11a, CD11b, CD11c, CD13, CD14, CD15, CD16, CD18, CD19, CD20, CD21, CD22, CD23, CD25, CD27L, CD28, CD29, CD30, CD30L, CD32, CD33 (p67 protein), CD34, CD38, CD40, CD40L, CD44, CD45, CD46, CD49a, CD52, CD54, CD55, CD56, CD61, CD64, CD66e, CD74, CD80 (B7-1), CD89, CD95, CD123, CD137, CD138, CD140a, CD146, CD147, CD148, CD152, CD164, CEACAM5, CFTR, cGMP, CINC, Clostridium botulinum toxin, Clostridium perfringens toxin, CKb8-1, CLC, CMV, CMV UL, CNTF, CNTN-1, COX, C-Ret, CRG-2, CT-1, CTACK, CTGF, CTLA-4, CX3CL1, CX3CR1, CXCL, CXCL1, CXCL2, CXCL3, CXCL4, CXCL5, CXCL6, CXCL7, CXCL8, CXCL9, CXCL10, CXCL11, CXCL12, CXCL13, CXCL14, CXCL15, CXCL16, CXCR, CXCR1, CXCR2, CXCR3, CXCR4, CXCR5, CXCR6, cytokeratin tumor-associated antigen, DAN, DCC, DcR3, DC-SIGN, decay accelerating factor, des(1-3)-IGF-I (brain IGF-1), Dhh, digoxin, DNAM-1, Dnase, Dpp, DPPIV/CD26, Dtk, ECAD, EDA, EDA-A1, EDA-A2, EDAR, EGF, EGFR (ErbB-1), EMA, EMMPRIN, ENA, endothelin receptor, enkephalinase, eNOS, Eot, eotaxin 1, EpCAM, ephrin B2/EphB4, EPO, ERCC, E-selectin, ET-1, factor Ha, factor VII, factor VIIIc, factor IX, fibroblast activation protein (FAP), Fas, FcR1, FEN-1, ferritin, FGF, FGF-19, FGF-2, FGF3, FGF-8, FGFR, FGFR-3, fibrin, FL, FLIP, Flt-3, Flt-4, follicle-stimulating hormone, fractalkine, FZD1, FZD2, FZD3, FZD4, FZD5, FZD6, FZD7, FZD8, FZD9, FZD10, G250, Gas6, GCP-2, GCSF, GD2, GD3, GDF, GDF-1, GDF-3 (Vgr-2), GDF-5 (BMP-14, CDMP-1), GDF-6 (BMP-13, CDMP-2), GDF-7 (BMP-12, CDMP-3), GDF-8 (myostatin), GDF-9, GDF-15 (MIC-1), GDNF, GDNF, GFAP, GFRa-1, GFR-alpha 1, GFR-alpha 2, GFR-alpha 3, GITR, glucagon, Glut4, glycoprotein IIb/IIIa (GPIIb/IIIa), GM-CSF, gp130, gp72, GRO, growth hormone-releasing factor, hapten (NP-cap or NIP-cap), HB-EGF, HCC, HCMV gB envelope glycoprotein, HCMV gH envelope glycoprotein, HCMV UL, hematopoietic growth factor (HGF), Hep B gp120, heparanase, Her2, Her2/neu (ErbB-2), Her3 (ErbB-3), Her4 (ErbB-4), herpes simplex virus (HSV) gB glycoprotein, HSV gD glycoprotein, HGFA, high-molecular-weight melanoma-associated antigen (HMW-MAA), HIV gp120, HIV IIIB gp 120 V3 loop, HLA, HLA-DR, HM1.24, HMFG PEM, HRG, Hrk, human heart myosin, human cytomegalovirus (HCMV), human growth hormone (HGH), HVEM, 1-309, IAP, ICAM, ICAM-1, ICAM-3, ICE, ICOS, IFNg, Ig, IgA receptor, IgE, IGF, IGF-binding protein, IGF-1R, IGFBP, IGF-I, IGF-II, IL, IL-1, IL-1R, IL-2, IL-2R, IL-4, IL-4R, IL-5, IL-5R, IL-6, IL-6R, IL-8, IL-9, IL-10, IL-12, IL-13, IL-15, IL-18, IL-18R, IL-23, interferon (INF)-alpha, INF-beta, INF-gamma, inhibin, iNOS, insulin A chain, insulin B chain, insulin-like growth factor 1, integrin alpha 2, integrin alpha 3, integrin alpha 4, integrin alpha 4/beta 1, integrin alpha 4/beta 7, integrin alpha 5 (alpha V), integrin alpha 5/beta 1, integrin alpha 5/beta 3, integrin alpha 6, integrin beta 1, integrin beta 2, interferon gamma, IP-10, I-TAC, JE, kallikrein 2, kallikrein 5, kallikrein 6, kallikrein 11, kallikrein 12, kallikrein 14, kallikrein 15, kallikrein L1, kallikrein L2, kallikrein L3, kallikrein L4, KC, KDR, keratinocyte growth factor (KGF), laminin 5, LAMP, LAP, LAP (TGF-1), latent TGF-1, latent TGF-1 bp1, LBP, LDGF, LECT2, lefty, Lewis-Y antigen, Lewis-Y-related antigen, LFA-1, LFA-3, Lfo, LIF, LIGHT, lipoprotein, LIX, LKN, Lptn, L-selectin, LT-a, LT-b, LTB4, LTBP-1, lung surfactant, luteinizing hormone, lymphotoxin beta receptor, Mac-1, MAdCAM, MAG, MAP2, MARC, MCAM, MCAM, MCK-2, MCP, M-CSF, MDC, Mer, METALLOPROTEASES, MGDF receptor, MGMT, MHC (HLA-DR), MIF, MIG, MIP, MIP-1-alpha, MK, MMAC1, MMP, MMP-1, MMP-10, MMP-11, MMP-12, MMP-13, MMP-14, MMP-15, MMP-2, MMP-24, MMP-3, MMP-7, MMP-8, MMP-9, MPIF, Mpo, MSK, MSP, mucin (Muc1), MUC18, mullerian-inhibiting factor, Mug, MuSK, NAIP, NAP, NCAD, N-cadherin, NCA 90, NCAM, NCAM, neprilysin, neurotrophin-3, -4, or -6, neurturin, nerve growth factor (NGF), NGFR, NGF-beta, nNOS, NO, NOS, Npn, NRG-3, NT, NTN, OB, OGG1, OPG, OPN, OSM, OX40L, OX40R, p150, p95, PADPr, parathyroid hormone, PARC, PARP, PBR, PBSF, PCAD, P-cadherin, PCNA, PDGF, PDGF, PDK-1, PECAM, PEM, PF4, PGE, PGF, PGI2, PGJ2, PIN, PLA2, placental alkaline phosphatase (PLAP), P1GF, PLP, PP14, proinsulin, prorelaxin, protein C, PS, PSA, PSCA, prostate-specific membrane antigen (PSMA), PTEN, PTHrp, Ptk, PTN, R51, RANK, RANKL, RANTES, RANTES, relaxin A chain, relaxin B chain, renin, respiratory syncytial virus (RSV) F, RSV Fgp, Ret, rheumatoid factor, RLIP76, RPA2, RSK, 5100, SCF/KL, SDF-1, SERINE, serum albumin, sFRP-3, Shh, SIGIRR, SK-1, SLAM, SLPI, SMAC, SMDF, SMOH, SOD, SPARC, Stat, STEAP, STEAP-II, TACE, TACI, TAG-72 (tumor-associated glycoprotein-72), TARC, TCA-3, T cell receptor (e.g., T cell receptor alpha/beta), TdT, TECK, TEM1, TEMS, TEM7, TEM8, TERT, testicular PLAP-like alkaline phosphatase, TfR, TGF, TGF-alpha, TGF-beta, TGF-beta Pan Specific, TGF-beta RI (ALK-5), TGF-beta RII, TGF-beta RIIb, TGF-beta RIII, TGF-beta 1, TGF-beta 2, TGF-beta 3, TGF-beta 4, TGF-beta 5, thrombin, thymus Ck-1, thyroid stimulating hormone, Tie, TIMP, TIQ, tissue factor, TMEFF2, Tmpo, TMPRSS2, TNF, TNF-alpha, TNF-alpha beta, TNF-beta 2, TNFc, TNF-RI, TNF-RII, TNFRSF10A (TRAIL R1 Apo-2, DR4), TNFRSF10B (TRAIL R2 DR5, KILLER, TRICK-2A, TRICK-B), TNFRSF10C (TRAIL R3 DcR1, LIT, TRID), TNFRSF10D (TRAIL R4 DcR2, TRUNDD), TNFRSF11A (RANK ODF R, TRANCE R), TNFRSF11B (OPG OCIF, TR1), TNFRSF12 (TWEAK R FN14), TNFRSF13B (TACI), TNFRSF13C (BAFF R), TNFRSF14 (HVEM ATAR, HveA, LIGHT R, TR2), TNFRSF16 (NGFR p75NTR), TNFRSF17 (BCMA), TNFRSF18 (GITR AITR), TNFRSF19 (TROY TAJ, TRADE), TNFRSF19L (RELT), TNFRSF1A (TNF RI CD120a, p55-60), TNFRSF1B (TNF RII CD120b, p75-80), TNFRSF26 (TNFRH3), TNFRSF3 (LTbR TNF RIII, TNFC R), TNFRSF4 (OX40 ACT35, TXGP1 R), TNFRSF5 (CD40 p50), TNFRSF6 (Fas Apo-1, APT1, CD95), TNFRSF6B (DcR3 M68, TR6), TNFRSF7 (CD27), TNFRSF8 (CD30), TNFRSF9 (4-1BB CD137, ILA), TNFRSF21 (DR6), TNFRSF22 (DcTRAIL R2 TNFRH2), TNFRST23 (DcTRAIL R1 TNFRH1), TNFRSF25 (DR3 Apo-3, LARD, TR-3, TRAMP, WSL-1), TNFSF10 (TRAIL Apo-2 ligand, TL2), TNFSF11 (TRANCE/RANK ligand ODF, OPG ligand), TNFSF12 (TWEAK Apo-3 ligand, DR3 ligand), TNFSF13 (APRIL TALL2), TNFSF13B (BAFF BLYS, TALL1, THANK, TNFSF20), TNFSF14 (LIGHT HVEM ligand, LTg), TNFSF15 (TL1A/VEGI), TNFSF18 (GITR ligand AITR ligand, TL6), TNFSF1A (TNF-a Conectin, DIF, TNFSF2), TNFSF1B (TNF-b LTa, TNFSF1), TNFSF3 (LTb TNFC, p33), TNFSF4 (OX40 ligand gp34, TXGP1), TNFSF5 (CD40 ligand CD154, gp39, HIGM1, IMD3, TRAP), TNFSF6 (Fas ligand Apo-1 ligand, APT1 ligand), TNFSF7 (CD27 ligand CD70), TNFSF8 (CD30 ligand CD153), TNFSF9 (4-1BB ligand CD137 ligand), TP-1, t-PA, Tpo, TRAIL, TRAIL R, TRAIL-R1, TRAIL-R2, TRANCE, transferrin receptor, TRF, Trk, TROP-2, TSG, TSLP, tumor-associated antigen CA125, tumor-associated antigen exhibiting Lewis Y-related carbohydrate, TWEAK, TXB2, Ung, uPAR, uPAR-1, urokinase, VCAM, VCAM-1, VECAD, VE-Cadherin, VE-cadherin-2, VEFGR-1 (flt-1), VEGF, VEGFR, VEGFR-3 (flt-4), VEGI, VIM, viral antigen, VLA, VLA-1, VLA-4, VNR integrin, von Willebrand factor, WIF-1, WNT1, WNT2, WNT2B/13, WNT3, WNT3A, WNT4, WNTSA, WNTSB, WNT6, WNT7A, WNT7B, WNT8A, WNT8B, WNT9A, WNT9A, WNT9B, WNT10A, WNT10B, WNT11, WNT16, XCL1, XCL2, XCR1, XCR1, XEDAR, XIAP, XPD, HMGB1, IgA, Aβ, CD81, CD97, CD98, DDR1, DKK1, EREG, Hsp90, IL-17/IL-17R, IL-20/IL-20R, oxidized LDL, PCSK9, prekallikrein, RON, TMEM16F, SOD1, Chromogranin A, Chromogranin B, tau, VAP1, high-molecular-weight kininogen, IL-31, IL-31R, Nav1.1, Nav1.2, Nav1.3, Nav1.4, Nav1.5, Nav1.6, Nav1.7, Nav1.8, Nav1.9, EPCR, C1, C1q, C1r, C1s, C2, C2a, C2b, C3, C3a, C3b, C4, C4a, C4b, C5, C5a, C5b, C6, C7, C8, C9, factor B, factor D, factor H, properdin, sclerostin, fibrinogen, fibrin, prothrombin, thrombin, tissue factor, factor V, factor Va, factor VII, factor VIIa, factor VIII, factor VIIIa, factor IX, factor IXa, factor X, factor Xa, factor XI, factor XIa, factor XII, factor XIIa, factor XIII, factor XIIIa, TFPI, antithrombin III, EPCR, thrombomodulin, TAPI, tPA, plasminogen, plasmin, PAI-1, PAI-2, GPC3, Syndecan-1, Syndecan-2, Syndecan-3, Syndecan-4, LPA, S1P, and receptors for hormone and growth factors.

[0166] The alteration of one or more amino acid residue(s) is acceptable for the amino acid sequence constituting each variable region as long as its antigen-binding activity is maintained. In the case of altering the amino acid sequence of the variable region, the alteration site, the type of the alteration, or the number of the amino acid to be altered is not particularly limited. For example, amino acid(s) present in CDRs and/or FRs can be appropriately altered. The variable region with the altered amino acid(s) preferably maintains its binding activity and preferably has, but not particularly limited to, for example, 50% or higher, more preferably 80% or higher, further preferably 100% or higher binding activity, compared with that before the alteration. Alternatively, the binding activity of the variable region may be increased by amino acid alteration and may be, for example, 2 times, 5 times, or 10 times the binding activity before the alteration. In the antibody of the present invention, the alteration of an amino acid sequence can be at least one of the substitution, deletion, addition, insertion, and modification of amino acid residue(s).

[0167] For example, the modification of N-terminal glutamine of the variable region to pyroglutamic acid by pyroglutamylation is a modification well known to those skilled in the art. Thus, the antibody of the present invention having glutamine at the N terminus of its heavy chain may contain a variable region with this N-terminal glutamine modified to pyroglutamic acid.

[0168] The variable regions of the antibody of the present invention may have arbitrary sequences and may be variable regions of an antibody of any origin, including mouse antibodies, rat antibodies, rabbit antibodies, goat antibodies, camel antibodies, humanized antibodies obtained by the humanization of these nonhuman antibodies, and human antibodies. The “humanized antibodies”, also called reshaped human antibodies, are obtained by grafting CDRs (complementarity determining regions) of a nonhuman mammal-derived antibody, for example, a mouse antibody to human antibody CDRs. Methods for identifying CDRs are known in the art (Kabat et al, Sequence of Proteins of Immunological Interest (1987), National Institute of Health, Bethesda, Md.; and Chothia et al, Nature (1989) 342, 877). General gene recombination approaches therefor are also known in the art (see European Patent Application Publication No. EP125023 and WO96/02576). Alternatively, various amino acid substitutions may be introduced to the variable regions of these antibodies in order to improve their antigen binding, pharmacokinetics, stability, or immunogenicity. The variable regions of the antibody of the present invention may bind to an antigen in a pH-dependent manner and be thereby capable of repetitively binding to the antigen (WO2009/125825).

[0169] The light chain constant region of the antibody includes x and X chain constant regions and can be any of these light chain constant regions. Alternatively, the light chain constant region according to the present invention may be a light chain constant region prepared by the alteration such as substitution, deletion, addition, insertion, and/or modification of amino acid(s).

[0170] The heavy chain constant region of the antibody includes, for example, IgA, IgD, IgE, IgG, and IgM constant regions. In the present invention, for example, an IgG heavy chain constant region, particularly, a mouse or human IgG heavy chain constant region, can be used. A mouse IgG1 heavy chain constant region is preferred.

[0171] The antibody of the present invention also includes modified forms of the antibody. Examples of the modified forms of the antibody can include antibodies conjugated with various molecules such as polyethylene glycol (PEG) or cytotoxic substances. Such modified forms of the antibody can be obtained by the chemical modification of the antibody of the present invention. The antibody modification method has already been established in the art.

[0172] In addition, the antibody of the present invention may be a multispecific antibody, particularly, a bispecific antibody. The multispecific antibody refers to an antibody having, in one antibody molecule, variable regions that recognize a plurality of different epitopes. The epitopes may be present in different molecules or may be present in the same molecule.

[0173] The polypeptide of the present invention can be produced by a method generally known to those skilled in the art. For example, the antibody can be prepared by the following method, though the method for preparing the antibody of the present invention is not limited thereto.

[0174] A DNA encoding the heavy chain of the antibody, which is a DNA encoding a heavy chain with one or more amino acid(s) in its Fc region altered to different amino acid(s), and a DNA encoding the light chain of the antibody are expressed. The DNA encoding a heavy chain with one or more amino acid(s) in its Fc region altered to different amino acid(s) can be obtained, for example, by obtaining the Fc region of a DNA encoding a naturally occurring heavy chain and appropriately altering a codon encoding the particular amino acid in the Fc region to a codon encoding the different amino acid.

[0175] Alternatively, a DNA encoding a heavy chain derived from a naturally occurring heavy chain by the alteration of one or more amino acid(s) in its Fc region to different amino acid(s) may be designed in advance and chemically synthesized to obtain a DNA encoding the heavy chain with one or more amino acid(s) in its Fc region altered to different amino acid(s). The amino acid alteration site, the type of the alteration, or the number of the amino acid to be altered is not particularly limited. The type of the alteration may be any of substitution, deletion, addition, insertion, and modification, or a combination thereof.

[0176] The DNA encoding the heavy chain with one or more amino acid(s) in its Fc region altered to different amino acid(s) can be produced as separate partial DNAs. Examples of the combination of the partial DNAs include, but not limited to: the combination of a variable region-encoding DNA and a constant region-encoding DNA; and the combination of a Fab region-encoding DNA and an Fc region-encoding DNA. Likewise, the light chain-encoding DNA can also be produced as separate partial DNAs.

[0177] These DNAs can be expressed by the following exemplary method: a heavy chain variable region-encoding DNA, together with a heavy chain constant region-encoding DNA, is incorporated into an expression vector to construct a heavy chain expression vector. Likewise, a light chain variable region-encoding DNA, together with a light chain constant region-encoding DNA, is incorporated into an expression vector to construct a light chain expression vector. These heavy chain- and light chain-encoding DNAs may be incorporated into a single expression vector.

[0178] The DNAs encoding the antibody heavy and light chains are incorporated into expression vectors so as to be expressed under the control of expression control regions, for example, an enhancer and a promoter. Next, host cells are transformed with the resulting expression vectors and allowed to express antibodies. In this case, appropriate hosts and expression vectors can be used in combination.

[0179] Examples of the vectors include M13 series vectors, pUC series vectors, pBR322, pBluescript, and pCR-Script. In addition to these vectors, for example, pGEM-T, pDIRECT, or pT7 can also be used for the purpose of cDNA subcloning and excision.

[0180] Particularly, expression vectors are useful for using the vectors for the purpose of producing the polypeptide of the present invention. For example, when the host is E. coli such as JM109, DH5α, HB101, or XL1-Blue, the expression vectors indispensably have a promoter that permits efficient expression in E. coli, for example, lacZ promoter (Ward et al., Nature (1989) 341, 544-546; and FASEB J (1992) 6, 2422-2427, which are incorporated herein by reference in their entirety), araB promoter (Better et al., Science (1988) 240, 1041-1043, which is incorporated herein by reference in its entirety), or T7 promoter. Examples of such vectors include the vectors mentioned above as well as pGEX-5X-1 (manufactured by Pharmacia), “QIAexpress system” (manufactured by Qiagen N. V.), pEGFP, and pET (in this case, the host is preferably BL21 expressing T7 RNA polymerase).

[0181] The vectors may contain a signal sequence for polypeptide secretion. In the case of production in the periplasm of E. coli, pelB signal sequence (Lei, S P et al, J Bacteriol (1987) 169, 4397, which is incorporated herein by reference in its entirety) can be used as the signal sequence for polypeptide secretion. The vectors can be transferred to the host cells using an approach generally known to those skilled in the art, for example, a calcium phosphate method, a DEAE-dextran method, a method using cationic ribosome DOTAP (manufactured by Boehringer Mannheim), electroporation, lipofection, or microinjection.

[0182] In addition to the E. coli-derived expression vectors, examples of the vectors for producing the polypeptide of the present invention include mammal-derived expression vectors (e.g., pcDNA3 (manufactured by Invitrogen Corp.), pEGF-BOS (Nucleic Acids Res 1990, 18 (17), 5322, which is incorporated herein by reference in its entirety), pEF, and pCDM8), insect cell-derived expression vectors (e.g., “Bac-to-BAC baculovirus expression system” (manufactured by GIBCO BRL), and pBacPAK8), plant-derived expression vectors (e.g., pMH1 and pMH2), animal virus-derived expression vectors (e.g., pHSV, pMV, and pAdexLcw), retrovirus-derived expression vectors (e.g., pZIPneo), yeast-derived expression vectors (e.g., “Pichia Expression Kit” (manufactured by Invitrogen Corp.), pNV11, and SP-Q01), and Bacillus subtilis-derived expression vectors (e.g., pPL608 and pKTH50).

[0183] 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, which is incorporated herein by reference in its entirety), MMTV-LTR promoter, EF1α promoter (Mizushima et al., Nucleic Acids Res (1990) 18, 5322, which is incorporated herein by reference in its entirety), CAG promoter (Gene (1991) 108, 193, which is incorporated herein by reference in its entirety), or CMV promoter and, more preferably, have a gene for screening for transformed cells (e.g., a drug resistance gene that can work as a marker by a drug (neomycin, G418, etc.)). Examples of the vectors having such properties include pMAM, pDR2, pBK-RSV, pBK-CMV, pOPRSV, and pOP13.

[0184] An exemplary method intended to stably express the gene and increase the number of intracellular gene copies involves transfecting CHO cells deficient in nucleic acid synthesis pathway with vectors having a DHFR gene serving as a complement thereto (e.g., pCHOI) and using methotrexate (MTX) in the gene amplification. An exemplary method intended to transiently express the gene involves using COS cells having an SV40 T antigen gene on their chromosomes to transform the cells with vectors having a replication origin of SV40 (pcD, etc.). Also, a replication origin derived from polyomavirus, adenovirus, bovine papillomavirus (BPV), or the like may be used. The expression vectors for increasing the number of gene copies can additionally contain a selection marker such as an aminoglycoside transferase (APH) gene, a thymidine kinase (TK) gene, an E. coli xanthine guanine phosphoribosyltransferase (Ecogpt) gene, or a dihydrofolate reductase (dhfr) gene. Also, cells given below can be used as host cells. In the case of using eukaryotic cells as the host cells, animal, plant, or fungus cells can be appropriately used. Specifically, examples of the animal cells can include the following cells:

[0185] (1) mammalian cells such as CHO (Chinese hamster ovary cell line), COS (monkey kidney cell line), myeloma cells (Sp2/0, NSO, etc.), BHK (baby hamster kidney cell line), Hela, Vero, HEK293 (human embryonic kidney cell line with sheared adenovirus (Ad)5 DNA), Freestyle 293, and PER. C6 cell (human embryonic retinal cell line transformed with the Adenovirus Type 5 (Ad5) E1A and E1B genes) (Current Protocols in Protein Science (May, 2001, Unit 5.9, Table 5.9.1));
(2) amphibian cells such as Xenopus oocytes; and
(3) insect cells such as sf9, sf21, and Tn5.

[0186] Alternatively, antibody gene expression systems using cells derived from plants of the genus Nicotiana such as Nicotiana tabacum as the plant cells are known in the art. Cultured callus cells can be appropriately used for the plant cell transformation. The following cells can be used as the fungus cells:

cells derived from yeasts of the genus Saccharomyces (e.g., Saccharomyces cerevisiae) and the genus Pichia (e.g., Pichia pastoris), and cells derived from filamentous fungi of the genus Aspergillus (e.g., Aspergillus niger).

[0187] The antibody thus expressed can be recovered, for example, by culturing the transformed cells, then recovering the extracellular culture solution or intracellular extracts, and separating and purifying the antibody therefrom. The antibody can be separated and purified by appropriately using in combination methods such as centrifugation, ammonium sulfate fractionation, salting out, ultrafiltration, affinity chromatography, ion-exchanged chromatography, and gel filtration chromatography.

[0188] The amino acid alteration can be performed by various methods known in the art. Preferred examples of these methods can include, but not limited to, site-directed mutagenesis (Hashimoto-Gotoh T, Mizuno T, Ogasahara Y and Nakagawa M (1995) An oligodeoxyribonucleotide-directed dual amber method for site-directed mutagenesis. Gene 152, 271-275, Zoller M J, and Smith M (1983) Oligonucleotide-directed mutagenesis of DNA fragments cloned into M13 vectors. Methods Enzymol 100, 468-500, Kramer W, Drutsa V, Jansen H W, Kramer B, Pflugfelder M and Fritz H J (1984) The gapped duplex DNA approach to oligonucleotide-directed mutation construction. Nucleic Acids Res 12, 9441-9456, Kramer W, and Fritz H J (1987) Oligonucleotide-directed construction of mutations via gapped duplex DNA. Methods Enzymol 154, 350-367, Kunkel T A (1985) Rapid and efficient site-specific mutagenesis without phenotypic selection. Proc Natl Acad Sci USA 82, 488-492), PCR mutagenesis, and cassette mutagenesis.

[0189] The substitution of an amino acid residue is carried out by replacement with another amino acid residue for the purpose of altering, for example, any of the following (a) to (c):

(a) the polypeptide backbone structure of a region having a sheet structure or helix structure;

(b) the electric charge or hydrophobicity of a target site; and

(c) the size of a side chain.

[0190] Amino acid residues are classified into the following groups on the basis of general side chain properties:

(1) hydrophobic residues: norleucine, Met, Ala, Val, Leu, and Ile;

(2) neutral hydrophilic residues: Cys, Ser, Thr, Asn, and Gln;

(3) acidic residues: Asp and Glu;

(4) basic residues: His, Lys, and Arg;

(5) residues that influence chain orientation: Gly and Pro; and

(6) aromatic residues: Trp, Tyr, and Phe.

[0191] The substitution of amino acid residues within each of these groups is called conservative substitution, while the substitution of an amino acid residue in one of these groups by an amino acid residue in another group is called non-conservative substitution. The substitution according to the present invention may be conservative substitution, non-conservative substitution, or a combination of conservative substitution and non-conservative substitution.

[0192] The amino acid modification of the present invention includes posttranslational modification. Specifically, the posttranslational modification can refer to the addition or deletion of a sugar chain. For example, an amino acid residue at EU numbering position 297 in an IgG1 heavy chain constant region can be modified with a sugar chain. Alternatively, sialic acid may be added to the sugar chain of the Fc region (MAbs 2010 September-October; 2 (5), 519-27). The sugar chain structure used in the modification is not limited. In general, antibodies expressed by eukaryotic cells involve sugar chain modification in their constant regions.

[0193] In this context, the eukaryotic cells include yeast and animal cells. For example, CHO cells or HEK293 cells are typical animal cells for use in transformation with expression vectors comprising antibody-encoding DNAs. On the other hand, the constant region of the present invention also includes regions lacking sugar chain modification at the position. The antibodies having sugar chain-unmodified constant regions can be obtained by the expression of their antibody-encoding genes in prokaryotic cells such as E. coli.

[0194] In the present invention, the binding activity of the polypeptide of the present invention against each FcγR can be measured by use of ELISA, FACS (fluorescence activated cell sorting), ALPHAScreen (amplified luminescent proximity homogeneous assay screen), the BIACORE method based on a surface plasmon resonance (SPR) phenomenon, or the like.

[0195] The ALPHAScreen method is carried out by the ALPHA technology using two types of beads (donor and acceptor) on the basis of the following principle: luminescence signals are detected only when these two beads are located in proximity through the biological interaction between a molecule bound with the donor bead and a molecule bound with the acceptor bead. A laser-excited photosensitizer in the donor bead converts ambient oxygen to singlet oxygen in an excited state. The singlet oxygen diffuses around the donor bead and reaches the acceptor bead located in proximity thereto to thereby cause chemiluminescent reaction in the bead, which finally emits light. In the absence of the interaction between the molecule bound with the donor bead and the molecule bound with the acceptor bead, singlet oxygen produced by the donor bead does not reach the acceptor bead. Thus, no chemiluminescent reaction occurs.

[0196] For example, a polypeptide comprising the Fc region of naturally occurring IgG is bound to the donor bead, and the Fcγ receptor is bound to the acceptor bead. In the absence of the polypeptide of the present invention comprising a mutated Fc region, the polypeptide comprising the Fc region of naturally occurring IgG interacts with the Fcγ receptor to generate luminescence signals of 520 to 620 nm. In the presence of the polypeptide of the present invention comprising a mutated Fc region, the polypeptide of the present invention competes with the polypeptide comprising the Fc region of naturally occurring IgG to inhibit its interaction with the Fcγ receptor. Decrease in luminescence signals generated as a result of the competition can be quantified to thereby determine relative binding activity. The polypeptide (e.g., antibody) of the present invention can be biotinylated by a method known in the art using sulfo-NHS-biotin or the like. The Fcγ receptor can be tagged with GST by an appropriately adopted method which involves, for example: fusing a polynucleotide encoding the Fcγ receptor in flame with a polynucleotide encoding GST; and allowing the resulting fusion gene to be expressed by cells or the like carrying vectors capable of expression thereof to express the GST-tagged Fcγ receptor, which is then purified using a glutathione column. The obtained luminescence signals are preferably analyzed using, for example, software GRAPHPAD PRISM (GraphPad Software, Inc., San Diego) adapted to a one-site competition model based on nonlinear regression analysis.

[0197] The BIACORE method based on a surface plasmon resonance (SPR) phenomenon is described as follows: one (ligand) of the substances between which the interaction is to be observed is immobilized on a thin gold film of a sensor chip. The sensor chip is irradiated with light from the back such that total reflection occurs at the interface between the thin gold film and glass. As a result, a site having a drop in reflection intensity (SPR signal) is formed in a portion of reflected light. The other (analyte) of the substances between which the interaction is to be observed is flowed on the surface of the sensor chip and thereby bound to the ligand so that the mass of the immobilized ligand molecule is increased to change the refractive index of the solvent on the sensor chip surface. This change in the refractive index shifts the position of the SPR signal (on the contrary, the dissociation of the bound molecules gets the signal back to the original position). The Biacore system plots on the vertical axis the amount of the shift, i.e., change in mass on the sensor chip surface, against time on the horizontal axis and thereby displays time-dependent change in mass as assay data (sensorgram). The amount of the analyte bound to the ligand captured on the sensor chip surface can be determined from the sensorgram. An association rate constant (ka) and a dissociation rate constant (kd) can be determined from the curve of the sensorgram, while a dissociation constant (KD) can be determined from the ratio between these constants. Inhibition assay is also preferably used in the BIACORE method (Proc Natl Acad Sci USA, 103 (11), 4005-4010, 2006).

[0198] The binding activity of the polypeptide of the present invention against each FcγR can be preferably measured using, for example, the BIACORE method based on a surface plasmon resonance (SPR) phenomenon, as shown later in Examples. Specifically, the polypeptide (e.g., antibody) of the present invention is immobilized directly or via protein A, protein L, protein A/G, protein G, an anti-lambda chain antibody, an anti-kappa chain antibody, an antigen peptide, an antigen protein, or the like onto a sensor chip, which is then allowed to interact with each FcγR as an analyte. The dissociation constant (KD) is calculated from results of analyzing the sensorgram. When the KD value is small, the binding activity can be confirmed to be high. When the KD value is large, the binding activity can be confirmed to be low. Alternatively, FcγR is immobilized directly or via an anti-tag antibody or the like onto a sensor chip, which is then allowed to interact with the polypeptide (e.g., antibody) of the present invention to be evaluated as an analyte. The dissociation constant (KD) is calculated from results of analyzing the sensorgram. When the KD value is small, the binding activity can be confirmed to be high. When the KD value is large, the binding activity can be confirmed to be low.

[0199] Alternatively, the binding activity of the polypeptide of the present invention may be measured on the basis of an amount bound instead of the KD value. In this context, the amount bound means an amount of the analyte bound under substantially the same amounts of the polypeptide to be evaluated, such as a value determined by dividing the difference in RU value in the sensorgram between before and after the interaction of the analyte with the polypeptide by the difference in RU value in the sensorgram between before and after the capturing of the polypeptide onto the sensor chip.

[0200] Specifically, the polypeptide (e.g., antibody) of the present invention is immobilized directly or via protein A, protein L, protein A/G, protein G, an anti-lambda chain antibody, an anti-kappa chain antibody, an antigen peptide, an antigen protein, or the like onto a sensor chip, which is then allowed to interact with each FcγR as an analyte. Then, the amount of change in resonance unit (RU) value on the sensorgram is divided by the amount of change in resonance unit (RU) derived from the polypeptide (e.g., antibody) of the present invention immobilized on the sensor chip to calculate a value. When the value is large, the binding activity can be confirmed to be high. When the value is small, the binding activity can be confirmed to be low. Alternatively, FcγR is immobilized directly or via an anti-tag antibody or the like onto a sensor chip, which is then allowed to interact with the polypeptide (e.g., antibody) of the present invention to be evaluated as an analyte. Then, the amount of change in resonance unit (RU) value on the sensorgram is divided by the amount of change in resonance unit (RU) derived from FcγR immobilized on the sensor chip to calculate a value. When the value is large, the binding activity can be confirmed to be high. When the value is small, the binding activity can be confirmed to be low.

[0201] The present invention also relates to a method for altering an Fc region such that the Fc region selectively binds to mouse FcγRII relative to mouse FcγRIII.

[0202] The present invention provides a method for altering a parent polypeptide comprising an Fc region to adjust a ratio of [KD value for mouse FcγRIII]/[KD value for mouse FcγRII] to 6 or more, the method comprising altering at least one amino acid in the Fc region. The present invention also provides a method for altering a parent polypeptide comprising an Fc region to improve the binding selectivity of the variant for mouse FcγRII relative to mouse FcγRIII by 5 times or more compared with that of the parent polypeptide, the method comprising altering at least one amino acid in the Fc region.

[0203] According to a preferred aspect, each method mentioned above may comprise, for example, the following steps:

obtaining a nucleic acid encoding the parent polypeptide comprising an Fc region;

altering the nucleic acid such that at least one amino acid in the Fc region is altered;

transferring the altered nucleic acid to a host cell, and culturing the host cell to express the polypeptide encoded by the nucleic acid; and

recovering the variant of the parent polypeptide from the cultures of the host cell.

[0204] In the method, the ratio of [KD value for mouse FcγRIII]/[KD value for mouse FcγRII] is adjusted to 6 or more, preferably 10 or more, 15 or more, 20 or more, 25 or more, or 30 or more, more preferably 35 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, or 90 or more. The binding selectivity of the variant for mouse FcγRII relative to mouse FcγRIII is improved by 5 times or more, preferably 10 times or more, 15 times or more, 20 times or more, 25 times or more, or 30 times or more, more preferably 35 times or more, 40 times or more, 50 times or more, 60 times or more, 70 times or more, 80 times or more, or 90 times or more, compared with that of the parent polypeptide.

[0205] One example of the preferred properties conferred by the method can include the property of strongly binding to mouse FcγRII. Specifically, the method preferably confers the following property:

the KD value for mouse FcγRII is 20 nM or smaller; or

the binding activity of the variant against mouse FcγRII is enhanced by 10 times or more compared with that of the parent polypeptide.

[0206] In the method, the KD value for mouse FcγRII is adjusted to 20 nM or smaller, preferably 10 nM or smaller, 4 nM or smaller, or 2 nM or smaller, more preferably 1.5 nM or smaller, 1 nM or smaller, 0.7 nM or smaller, or 0.5 nM or smaller. Also, the binding activity of the variant against mouse FcγRII is enhanced by 10 times or more, preferably 20 times or more, 50 times or more, or 100 times or more, more preferably 150 times or more, 200 times or more, 300 times or more, or 400 times or more, compared with that of the parent polypeptide.

[0207] Examples of the amino acid alteration that can confer the property as mentioned above include the alteration of an amino acid at EU numbering position 230, the alteration of an amino acid at EU numbering position 231, the alteration of an amino acid at EU numbering position 232, the alteration of an amino acid at EU numbering position 238, the alteration of an amino acid at EU numbering position 239, the alteration of an amino acid at EU numbering position 240, the alteration of an amino acid at EU numbering position 241, the alteration of an amino acid at EU numbering position 266, the alteration of an amino acid at EU numbering position 267, the alteration of an amino acid at EU numbering position 268, the alteration of an amino acid at EU numbering position 271, the alteration of an amino acid at EU numbering position 295, the alteration of an amino acid at EU numbering position 296, the alteration of an amino acid at EU numbering position 298, the alteration of an amino acid at EU numbering position 324, the alteration of an amino acid at EU numbering position 326, the alteration of an amino acid at EU numbering position 327, the alteration of an amino acid at EU numbering position 330, the alteration of an amino acid at EU numbering position 331, the alteration of an amino acid at EU numbering position 333, the alteration of an amino acid at EU numbering position 334, the alteration of an amino acid at EU numbering position 335, and the alteration of an amino acid at EU numbering position 337. One of these amino acid alterations may be carried out, or two or more thereof may be combined

[0208] Examples of a further preferred amino acid alteration include an alteration that substitutes an amino acid at EU numbering position 230 by Asp, Glu, Ile, Pro, Gln, or Val, an alteration that substitutes an amino acid at EU numbering position 231 by Ala, Asp, Glu, Ile, Leu, Met, Asn, Pro, Gln, Thr, or Trp, an alteration that substitutes an amino acid at EU numbering position 232 by Ala, Asp, Glu, Phe, Leu, Asn, Val, Trp, or Tyr, an alteration that substitutes an amino acid at EU numbering position 238 by Glu, Pro, or Gln, an alteration that substitutes an amino acid at EU numbering position 239 by Ala, Asp, Glu, Phe, Gly, His, Ile, Leu, Met, Asn, Pro, Gln, Arg, Thr, Val, Trp, or Tyr, an alteration that substitutes an amino acid at EU numbering position 240 by Glu, His, Gln, or Trp, an alteration that substitutes an amino acid at EU numbering position 241 by Trp or Tyr, an alteration that substitutes an amino acid at EU numbering position 266 by Leu, an alteration that substitutes an amino acid at EU numbering position 267 by Ala or Glu, an alteration that substitutes an amino acid at EU numbering position 268 by Asp, an alteration that substitutes an amino acid at EU numbering position 271 by Leu, an alteration that substitutes an amino acid at EU numbering position 295 by Leu, an alteration that substitutes an amino acid at EU numbering position 296 by Glu, Asn, Thr, or Trp, an alteration that substitutes an amino acid at EU numbering position 298 by Leu or Met, an alteration that substitutes an amino acid at EU numbering position 324 by Asp, Leu, or Met, an alteration that substitutes an amino acid at EU numbering position 326 by Asp, an alteration that substitutes an amino acid at EU numbering position 327 by Gly, an alteration that substitutes an amino acid at EU numbering position 330 by Gly, Lys, or Gln, an alteration that substitutes an amino acid at EU numbering position 331 by Asp, Phe, or Tyr, an alteration that substitutes an amino acid at EU numbering position 333 by Asn, Val, or Tyr, an alteration that substitutes an amino acid at EU numbering position 334 by Arg, an alteration that substitutes an amino acid at EU numbering position 335 by Asn or Tyr, and an alteration that substitutes an amino acid at EU numbering position 337 by Ile, Lys, or Trp. One of these alterations may be carried out, or two or more thereof may be combined. Preferred examples of such alterations include alterations described in Tables 2 to 17, 24, and 25.

[0209] Another example of the preferred properties conferred by the method can include the property of weakly binding to mouse FcγRIII. Specifically, the method preferably confers the following property:

the KD value for mouse FcγRIII is 1 μM or larger; or

the binding activity of the variant against mouse FcγRIII is reduced to 0.25 times or less that of the parent polypeptide.

[0210] In the method, the KD value for mouse FcγRIII is adjusted to 1 μM or larger, preferably 1.2 μM or larger, 1.5 μM or larger, or 2 μM or larger, more preferably 2.5 μM or larger, 3 μM or larger, 4 μM or smaller, or 5 μM or larger. Also, the binding activity of the variant against mouse FcγRIII is reduced to 0.25 times or less, preferably 0.20 times or less, 0.18 times or less, 0.16 times or less, or 0.14 times or less, more preferably 0.12 times or less, 0.10 times or less, 0.08 times or less, or 0.06 times or less that of the parent polypeptide.

[0211] Examples of the amino acid alteration that can confer the property as mentioned above include the alteration of an amino acid at EU numbering position 230, the alteration of an amino acid at EU numbering position 231, the alteration of an amino acid at EU numbering position 232, the alteration of an amino acid at EU numbering position 237, the alteration of an amino acid at EU numbering position 238, the alteration of an amino acid at EU numbering position 239, the alteration of an amino acid at EU numbering position 241, the alteration of an amino acid at EU numbering position 267, and the alteration of an amino acid at EU numbering position 298. One of these amino acid alterations may be carried out, or two or more thereof may be combined

[0212] Examples of a further preferred amino acid alteration include an alteration that substitutes an amino acid at EU numbering position 230 by Glu, Ile, or Gln, an alteration that substitutes an amino acid at EU numbering position 231 by Ala, Asp, Asn, Pro, or Thr, an alteration that substitutes an amino acid at EU numbering position 232 by Ala, Lys, Asn, or Tyr, an alteration that substitutes an amino acid at EU numbering position 237 by Glu, an alteration that substitutes an amino acid at EU numbering position 238 by Asp or Glu, an alteration that substitutes an amino acid at EU numbering position 239 by Asp, Glu, Phe, Lys, Leu, Asn, Trp, or Tyr, an alteration that substitutes an amino acid at EU numbering position 241 by Asp, Glu, or Thr, an alteration that substitutes an amino acid at EU numbering position 267 by Met, and an alteration that substitutes an amino acid at EU numbering position 298 by His. One of these alterations may be carried out, or two or more thereof may be combined. Preferred examples of such alterations include alterations described in Tables 18 to 23, 26, and 27.

[0213] A further example of the preferred properties conferred by the method can include the property of binding to mouse FcγRII with strength equivalent to or higher than that of the parent polypeptide and binding to mouse FcγRIII more weakly compared with the parent polypeptide.

Specifically, the method preferably confers the following property:

the KD value for mouse FcγRII is 400 nM or smaller, and the KD value for mouse FcγRIII is 1 μM or larger; or

the binding activity of the variant against mouse FcγRII is 0.5 times or more that of the parent polypeptide, and the binding activity of the variant against mouse FcγRIII is 0.25 times or less that of the parent polypeptide.

[0214] In the method, the KD value for mouse FcγRII is adjusted to 400 nM or smaller, preferably 360 nM or smaller, 320 nM or smaller, or 280 nM or smaller, more preferably 250 nM or smaller, 200 nM or smaller, 150 nM or smaller, or 100 nM or smaller, and the KD value for mouse FcγRIII is adjusted to 1 μM or larger, preferably 1.2 μM or larger, 1.5 μM or larger, or 2 μM or larger, more preferably 2.5 μM or larger, 3 μM or larger, 4 μM or larger, or 5 μM or larger. Also, the binding activity of the variant against mouse FcγRII is adjusted to 0.5 times or more, preferably 0.6 times or more, 0.75 times or more, or 1.0 times or more, more preferably 1.5 times or more, 2 times or more, 2.5 times or more, or 3 times or more that of the parent polypeptide, and the binding activity of the variant against mouse FcγRIII is adjusted to 0.25 times or less, preferably 0.20 times or less, 0.18 times or less, 0.16 times or less, or 0.14 times or less, more preferably 0.12 times or less, 0.10 times or less, 0.08 times or less, or 0.06 times or less that of the parent polypeptide.

[0215] Polypeptides produced by alteration according to the method are also included in the scope of the present invention.

[0216] The present invention also relates to a method for producing an Fc variant selectively binding to mouse FcγRII relative to mouse FcγRIII.

[0217] The present invention provides a method for producing a polypeptide which is a variant of a parent polypeptide comprising an Fc region, wherein the polypeptide has a ratio of [KD value for mouse FcγRIII]/[KD value for mouse FcγRII] of 6 or more, the method comprising altering at least one amino acid in the Fc region. The present invention also provides a method for producing a polypeptide which is a variant of a parent polypeptide comprising an Fc region, wherein the binding selectivity of the polypeptide for mouse FcγRII relative to mouse FcγRIII is improved by 5 times or more compared with that of the parent polypeptide, the method comprising altering at least one amino acid in the Fc region.

[0218] According to a preferred aspect, each method mentioned above may comprise, for example, the following steps:

obtaining a nucleic acid encoding the parent polypeptide comprising an Fc region;

altering the nucleic acid such that at least one amino acid in the Fc region is altered;

transferring the altered nucleic acid to a host cell, and culturing the host cell to express the polypeptide encoded by the nucleic acid; and

recovering the variant of the parent polypeptide from the cultures of the host cell.

[0219] In the method, the ratio of [KD value for mouse FcγRIII]/[KD value for mouse FcγRII] is 6 or more, preferably 10 or more, 15 or more, 20 or more, 25 or more, or 30 or more, more preferably 35 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, or 90 or more. The binding selectivity of the polypeptide for mouse FcγRII relative to mouse FcγRIII is improved by 5 times or more, preferably 10 times or more, 15 times or more, 20 times or more, 25 times or more, or 30 times or more, more preferably 35 times or more, 40 times or more, 50 times or more, 60 times or more, 70 times or more, 80 times or more, or 90 times or more, compared with that of the parent polypeptide.

[0220] One example of the preferred properties possessed by the polypeptide produced by the method can include the property of strongly binding to mouse FcγRII. Specifically, the polypeptide preferably has the following property:

the KD value for mouse FcγRII is 20 nM or smaller; or

the binding activity of the polypeptide against mouse FcγRII is enhanced by 10 times or more compared with that of the parent polypeptide.

[0221] In the method, the KD value for mouse FcγRII is 20 nM or smaller, preferably 10 nM or smaller, 4 nM or smaller, or 2 nM or smaller, more preferably 1.5 nM or smaller, 1 nM or smaller, 0.7 nM or smaller, or 0.5 nM or smaller. Also, the binding activity of the polypeptide against mouse FcγRII is enhanced by 10 times or more, preferably 20 times or more, 50 times or more, or 100 times or more, more preferably 150 times or more, 200 times or more, 300 times or more, or 400 times or more, compared with that of the parent polypeptide.

[0222] Examples of the amino acid alteration that can confer the property as mentioned above include the alteration of an amino acid at EU numbering position 230, the alteration of an amino acid at EU numbering position 231, the alteration of an amino acid at EU numbering position 232, the alteration of an amino acid at EU numbering position 238, the alteration of an amino acid at EU numbering position 239, the alteration of an amino acid at EU numbering position 240, the alteration of an amino acid at EU numbering position 241, the alteration of an amino acid at EU numbering position 266, the alteration of an amino acid at EU numbering position 267, the alteration of an amino acid at EU numbering position 268, the alteration of an amino acid at EU numbering position 271, the alteration of an amino acid at EU numbering position 295, the alteration of an amino acid at EU numbering position 296, the alteration of an amino acid at EU numbering position 298, the alteration of an amino acid at EU numbering position 324, the alteration of an amino acid at EU numbering position 326, the alteration of an amino acid at EU numbering position 327, the alteration of an amino acid at EU numbering position 330, the alteration of an amino acid at EU numbering position 331, the alteration of an amino acid at EU numbering position 333, the alteration of an amino acid at EU numbering position 334, the alteration of an amino acid at EU numbering position 335, and the alteration of an amino acid at EU numbering position 337. One of these amino acid alterations may be carried out, or two or more thereof may be combined.

[0223] Examples of a further preferred amino acid alteration include an alteration that substitutes an amino acid at EU numbering position 230 by Asp, Glu, Ile, Pro, Gln, or Val, an alteration that substitutes an amino acid at EU numbering position 231 by Ala, Asp, Glu, Ile, Leu, Met, Asn, Pro, Gln, Thr, or Trp, an alteration that substitutes an amino acid at EU numbering position 232 by Ala, Asp, Glu, Phe, Leu, Asn, Val, Trp, or Tyr, an alteration that substitutes an amino acid at EU numbering position 238 by Glu, Pro, or Gln, an alteration that substitutes an amino acid at EU numbering position 239 by Ala, Asp, Glu, Phe, Gly, His, Ile, Leu, Met, Asn, Pro, Gln, Arg, Thr, Val, Trp, or Tyr, an alteration that substitutes an amino acid at EU numbering position 240 by Glu, His, Gln, or Trp, an alteration that substitutes an amino acid at EU numbering position 241 by Trp or Tyr, an alteration that substitutes an amino acid at EU numbering position 266 by Leu, an alteration that substitutes an amino acid at EU numbering position 267 by Ala or Glu, an alteration that substitutes an amino acid at EU numbering position 268 by Asp, an alteration that substitutes an amino acid at EU numbering position 271 by Leu, an alteration that substitutes an amino acid at EU numbering position 295 by Leu, an alteration that substitutes an amino acid at EU numbering position 296 by Glu, Asn, Thr, or Trp, an alteration that substitutes an amino acid at EU numbering position 298 by Leu or Met, an alteration that substitutes an amino acid at EU numbering position 324 by Asp, Leu, or Met, an alteration that substitutes an amino acid at EU numbering position 326 by Asp, an alteration that substitutes an amino acid at EU numbering position 327 by Gly, an alteration that substitutes an amino acid at EU numbering position 330 by Gly, Lys, or Gln, an alteration that substitutes an amino acid at EU numbering position 331 by Asp, Phe, or Tyr, an alteration that substitutes an amino acid at EU numbering position 333 by Asn, Val, or Tyr, an alteration that substitutes an amino acid at EU numbering position 334 by Arg, an alteration that substitutes an amino acid at EU numbering position 335 by Asn or Tyr, and an alteration that substitutes an amino acid at EU numbering position 337 by Ile, Lys, or Trp. One of these alterations may be carried out, or two or more thereof may be combined. Preferred examples of such alterations include alterations described in Tables 2 to 17, 24, and 25.

[0224] Another example of the preferred properties possessed by the polypeptide produced by the method can include the property of weakly binding to mouse FcγRIII. Specifically, the polypeptide preferably has the following property:

the KD value for mouse FcγRIII is 1 μM or larger; or

the binding activity of the polypeptide against mouse FcγRIII is reduced to 0.25 times or less that of the parent polypeptide.

[0225] In the method, the KD value for mouse FcγRIII is 1 μM or larger, preferably 1.2 μM or larger, 1.5 μM or larger, or 2 μM or larger, more preferably 2.5 μM or larger, 3 μM or larger, 4 μM or larger, or 5 μM or larger. Also, the binding activity of the polypeptide against mouse FcγRIII is reduced to 0.25 times or less, preferably 0.20 times or less, 0.18 times or less, 0.16 times or less, or 0.14 times or less, more preferably 0.12 times or less, 0.10 times or less, 0.08 times or less, or 0.06 times or less that of the parent polypeptide.

[0226] Examples of the amino acid alteration that can confer the property as mentioned above include the alteration of an amino acid at EU numbering position 230, the alteration of an amino acid at EU numbering position 231, the alteration of an amino acid at EU numbering position 232, the alteration of an amino acid at EU numbering position 237, the alteration of an amino acid at EU numbering position 238, the alteration of an amino acid at EU numbering position 239, the alteration of an amino acid at EU numbering position 241, the alteration of an amino acid at EU numbering position 267, and the alteration of an amino acid at EU numbering position 298. One of these amino acid alterations may be carried out, or two or more thereof may be combined.

[0227] Examples of a further preferred amino acid alteration include an alteration that substitutes an amino acid at EU numbering position 230 by Glu, Ile, or Gln, an alteration that substitutes an amino acid at EU numbering position 231 by Ala, Asp, Asn, Pro, or Thr, an alteration that substitutes an amino acid at EU numbering position 232 by Ala, Lys, Asn, or Tyr, an alteration that substitutes an amino acid at EU numbering position 237 by Glu, an alteration that substitutes an amino acid at EU numbering position 238 by Asp or Glu, an alteration that substitutes an amino acid at EU numbering position 239 by Asp, Glu, Phe, Lys, Leu, Asn, Trp, or Tyr, an alteration that substitutes an amino acid at EU numbering position 241 by Asp, Glu, or Thr, an alteration that substitutes an amino acid at EU numbering position 267 by Met, and an alteration that substitutes an amino acid at EU numbering position 298 by His. One of these alterations may be carried out, or two or more thereof may be combined. Preferred examples of such alterations include alterations described in Tables 18 to 23, 26, and 27.

[0228] A further example of the preferred properties possessed by the polypeptide produced by the method can include the property of binding to mouse FcγRII with strength equivalent to or higher than that of the parent polypeptide and binding to mouse FcγRIII more weakly compared with the parent polypeptide. Specifically, the polypeptide preferably has the following property:

the KD value for mouse FcγRII is 400 nM or smaller, and the KD value for mouse FcγRIII is 1 μM or larger; or

the binding activity of the polypeptide against mouse FcγRII is 0.5 times or more that of the parent polypeptide, and the binding activity of the polypeptide against mouse FcγRIII is 0.25 times or less that of the parent polypeptide.

[0229] In the method, the KD value for mouse FcγRII is 400 nM or smaller, preferably 360 nM or smaller, 320 nM or smaller, or 280 nM or smaller, more preferably 250 nM or smaller, 200 nM or smaller, 150 nM or smaller, or 100 nM or smaller, and the KD value for mouse FcγRIII is 1 μM or larger, preferably 1.2 μM or larger, 1.5 μM or larger, or 2 μM or larger, more preferably 2.5 μM or larger, 3 μM or larger, 4 μM or larger, or 5 μM or larger. Also, the binding activity of the polypeptide against mouse FcγRII is 0.5 times or more, preferably 0.6 times or more, 0.75 times or more, or 1.0 times or more, more preferably 1.5 times or more, 2 times or more, 2.5 times or more, or 3 times or more that of the parent polypeptide, and the binding activity of the polypeptide against mouse FcγRIII is 0.25 times or less, preferably 0.20 times or less, 0.18 times or less, 0.16 times or less, or 0.14 times or less, more preferably 0.12 times or less, 0.10 times or less, 0.08 times or less, or 0.06 times or less that of the parent polypeptide.

[0230] Polypeptides produced by the method are also included in the scope of the present invention.

[0231] The present invention also encompasses a nucleic acid encoding the polypeptide of the present invention. The nucleic acid of the present invention may be in any form such as DNA or RNA.

[0232] The present invention further encompasses a vector comprising the nucleic acid of the present invention. The type of the vector can be appropriately selected by those skilled in the art according to host cells to which the vector is transferred. For example, any of the vectors mentioned above can be used.

[0233] The present invention further encompasses a host cell transformed with the vector of the present invention. The host cell can be appropriately selected by those skilled in the art. For example, any of the host cells mentioned above can be used.

[0234] The present invention provides a pharmaceutical composition comprising the polypeptide of the present invention as an active ingredient. The pharmaceutical composition of the present invention can be formulated according to a method known in the art by using the polypeptide of the present invention in combination with a pharmaceutically acceptable carrier. For example, the pharmaceutical composition may be formulated with the polypeptide of the present invention mixed in a unit dosage form required for generally accepted pharmaceutical practice, in appropriate combination with pharmacologically acceptable carriers or media, specifically, sterilized water, physiological saline, plant oil, an emulsifier, a suspending agent, a surfactant, a stabilizer, a flavoring agent, an excipient, a vehicle, a preservative, a binder, etc. Examples of the carrier can include light anhydrous silicic acid, lactose, crystalline cellulose, mannitol, starch, carmellose calcium, carmellose sodium, hydroxypropylcellulose, hydroxypropylmethylcellulose, polyvinyl acetal diethylaminoacetate, polyvinylpyrrolidone, gelatin, medium-chain fatty acid triglyceride, polyoxyethylene hydrogenated castor oil 60, saccharide, carboxymethylcellulose, cornstarch, and inorganic salts. The amount of the active ingredient in such a preparation can be appropriately determined within the prescribed range of doses.

[0235] Examples of aqueous solutions for injection include isotonic solutions or physiological saline containing glucose, D-sorbitol, D-mannose, D-mannitol, sodium chloride, and the like. These solutions may be used in combination with an appropriate solubilizer, for example, an alcohol (ethanol, propylene glycol, polyethylene glycol, etc.) or a nonionic surfactant (polysorbate 80(TM), HCO-50, etc.).

[0236] Examples of oily solutions include sesame oil and soybean oil. These solutions may be used in combination with benzyl benzoate or benzyl alcohol as a solubilizer. The solutions may be further mixed with a buffer (a phosphate buffer solution, a sodium acetate buffer solution, etc.), a soothing agent (procaine hydrochloride, etc.), a stabilizer (benzyl alcohol, phenol, etc.), an antioxidant, and the like. The injection solutions thus prepared are usually charged into appropriate ampules.

[0237] The dose or administration method of the pharmaceutical composition of the present invention varies depending on the body weight, age, symptoms, etc. of a patient and can be appropriately selected by those skilled in the art. The single dose thereof can be selected, for example, within a range of 0.0001 mg to 1000 mg per kg of body weight or within a range of 0.001 to 100000 mg/body per patient, though the dose is not necessarily limited to these numeric values. Oral administration or parenteral administration may be selected as an administration method. Parenteral administration is preferred. Examples of the parenteral administration include injection, intranasal administration, transpulmonary administrations, and percutaneous administration. Examples of the injection include intravenous injection, intramuscular injection, intraperitoneal injection, and subcutaneous injection. The pharmaceutical composition can be administered systemically or locally through these administration methods.

[0238] The present invention also relates to a method for using the polypeptide comprising an Fc variant selectively binding to mouse FcγRII relative to mouse FcγRIII to predict the effects, on a human, of a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa.

[0239] Even an Fc variant that exhibits binding selectivity for human FcγRIIb is likely to exhibit no binding selectivity for mouse FcγRII due to difference of species cross-reactivity. For this reason, it has been difficult to evaluate drug effects, safety, etc. in animal (e.g., mouse) models in an attempt to develop a drug having the feature to selectively bind to human FcγRIIb using the Fc variant. The Fc variant found in the present invention which selectively binds to mouse FcγRII is very useful in terms of improving this situation and enabling effects, safety, etc. to be evaluated in mice. As shown later in Examples, members of the FcγR family other than mouse FcγRII (or human FcγRIIb) seem to also participate in time-dependent change in the concentration of a polypeptide comprising an Fc region, such as an antibody, in blood. In this respect, the polypeptide of the present invention selectively binding to mouse FcγRII is indispensable for accurately evaluating, in mice, the effects or safety of a drug having the feature to selectively bind to human FcγRIIb.

[0240] The present invention provides a method for predicting a therapeutic or preventive effect on a disease when a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa is administered to a human, the method comprising the steps of administering a polypeptide comprising an Fc variant selectively binding to mouse FcγRII relative to mouse FcγRIII, to a mouse model of the human disease and evaluating the therapeutic or preventive effect thereof.

[0241] Specifically, according to a preferred aspect, the method may comprise, for example, the following steps:

(a) obtaining a polypeptide comprising an antigen-binding region binding to a mouse antigen;

(b) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and the Fc variant of the present invention;

(c) administering the polypeptide prepared in step (b) to a mouse model of a human disease; and

[0242] (d) when a therapeutic or preventive effect on the disease is observed in the mouse as a result of step (c), determining that a polypeptide comprising an antigen-binding region binding to a human counterpart of the mouse antigen, and the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa is effective for the treatment or prevention of the human disease.

[0243] According to a more preferred aspect, the method may further comprise steps (b′) and (c′) in addition to the steps (b) and (c) and the step (d) may be a step given below:

(b′) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and the Fc region of naturally occurring IgG; and

(c′) administering the polypeptide prepared in step (b′) to a mouse model of a human disease, and

[0244] (d) when a stronger therapeutic or preventive effect on the disease is observed in the mouse that has received the polypeptide of step (b) than in the mouse that has received the polypeptide of step (b′) as a result of steps (c) and (c′), determining that a polypeptide comprising an antigen-binding region binding to a human counterpart of the mouse antigen, and the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa is effective for the treatment or prevention of the human disease.

[0245] The present invention provides a method for selecting a disease suitable for treatment or prevention using a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa, the method comprising the steps of administering a polypeptide comprising an Fc variant selectively binding to mouse FcγRII relative to mouse FcγRIII, to a mouse model of a human disease and evaluating the therapeutic or preventive effect thereof.

[0246] Specifically, according to a preferred aspect, the method may comprise, for example, the following steps:

(a) obtaining a polypeptide comprising an antigen-binding region binding to a mouse antigen;

(b) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and the Fc variant of the present invention;

(c) administering the polypeptide prepared in step (b) to a mouse model of a human disease; and

[0247] (d) when a therapeutic or preventive effect on the disease is observed in the mouse as a result of step (c), selecting the human disease as the disease suitable for treatment or prevention using a polypeptide comprising an antigen-binding region binding to a human counterpart of the mouse antigen, and the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa.

[0248] According to a more preferred aspect, the method may further comprise steps (b′) and (c′) in addition to the steps (b) and (c) and the step (d) may be a step given below:

(b′) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and the Fc region of naturally occurring IgG; and

(c′) administering the polypeptide prepared in step (b′) to a mouse model of a human disease, and

[0249] (d) when a stronger therapeutic or preventive effect on the disease is observed in the mouse that has received the polypeptide of step (b) than in the mouse that has received the polypeptide of step (b′) as a result of steps (c) and (c′), selecting the human disease as the disease suitable for treatment or prevention using a polypeptide comprising an antigen-binding region binding to a human counterpart of the mouse antigen, and the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa.

[0250] The present invention provides a method for selecting a target antigen suitable for treatment or prevention using a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa, the method comprising the steps of administering a polypeptide comprising an Fc variant selectively binding to mouse FcγRII relative to mouse FcγRIII, to a mouse model of a human disease and evaluating the therapeutic or preventive effect thereof.

[0251] Specifically, according to a preferred aspect, the method may comprise, for example, the following steps:

(a) obtaining a polypeptide comprising an antigen-binding region binding to a mouse antigen;

(b) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and the Fc variant of the present invention;

(c) administering the polypeptide prepared in step (b) to a mouse model of a human disease; and

[0252] (d) when a therapeutic or preventive effect on the disease is observed in the mouse as a result of step (c), selecting a human counterpart of the mouse antigen as the target antigen suitable for treatment or prevention using a polypeptide comprising the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa.

[0253] According to a more preferred aspect, the method may further comprise steps (b′) and (c′) in addition to the steps (b) and (c) and the step (d) may be a step given below:

(b′) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and the Fc region of naturally occurring IgG; and

(c′) administering the polypeptide prepared in step (b′) to a mouse model of a human disease, and

[0254] (d) when a stronger therapeutic or preventive effect on the disease is observed in the mouse that has received the polypeptide of step (b) than in the mouse that has received the polypeptide of step (b′) as a result of steps (c) and (c′), selecting a human counterpart of the mouse antigen as the target antigen suitable for treatment or prevention using a polypeptide comprising the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa.

[0255] The present invention provides a method for selecting an antigen-binding region suitable for treatment or prevention using a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa, the method comprising the steps of administering a polypeptide comprising an Fc variant selectively binding to mouse FcγRII relative to mouse FcγRIII, to a mouse model of a human disease and evaluating the therapeutic or preventive effect thereof.

[0256] Specifically, according to a preferred aspect, the method may comprise, for example, the following steps:

(a) obtaining a plurality of polypeptides comprising antigen-binding regions binding to the same mouse antigen;

(b) preparing a polypeptide comprising each of the antigen-binding regions of the polypeptides obtained in step (a), and the Fc variant of the present invention;

(c) administering the polypeptide prepared in step (b) to a mouse model of a human disease; and

[0257] (d) as a result of step (c), selecting the antigen-binding region of a polypeptide that exhibits a stronger therapeutic or preventive effect as the antigen-binding region suitable for treatment or prevention of the human disease using a polypeptide comprising the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa.

[0258] The present invention provides a method for predicting safety or toxicity when a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa is administered to a human, the method comprising the steps of administering a polypeptide comprising an Fc variant selectively binding to mouse FcγRII relative to mouse FcγRIII, to a mouse and evaluating the safety or toxicity thereof.

[0259] In the aforementioned method for selecting an antigen-binding region, the mouse antigen is preferably identical to the human antigen as mentioned later. Specifically, a genetically modified mouse prepared by the transfer of a human gene is selected as the mouse model of a human disease, and a gene product expressed from the human gene is used as the mouse antigen in this method. As a result, the optimum antigen-binding region is preferably selected from among a plurality of antigen-binding regions binding to the human gene product.

[0260] In drug development, safety tests are carried out at the preclinical stage using monkeys or rodents such as mice. Depending on animal species, however, the target antigen is low homologous to its human counterpart. A development candidate drug therefore may not cross-react with the monkey or mouse antigen. Particularly, the mouse antigen is low analogous to its human counterpart and often does not have sufficient cross-reactivity. In such a case, the development candidate may be evaluated for its safety by use of a surrogate binding to the mouse target antigen with strength or properties similar to those of the human target antigen (reference: MAbs, 2009, 1 (1), 2-11). Likewise, the Fc variant of the present invention can be used as a mouse surrogate for an Fc variant selectively binding to human FcγRIIb. The polypeptide (preferably, antibody, etc.) comprising the Fc variant of the present invention can be administered to a mouse to thereby evaluate the safety of the polypeptide comprising an Fc variant selectively binding to human FcγRIIb.

[0261] Specifically, according to a preferred aspect, the method may comprise, for example, the following step:

(a) obtaining a polypeptide comprising an antigen-binding region binding to a mouse antigen;

(b) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and the Fc variant of the present invention;

(c) administering the polypeptide prepared in step (b) to a mouse; and

[0262] (d) analogically inferring the safety or toxicity, in a human, of a polypeptide comprising an antigen-binding region binding to a human counterpart of the mouse antigen, and the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa from the results obtained in step (c) about the safety or toxicity of the polypeptide of step (b) in the mouse.

[0263] The present invention provides a method for predicting pharmacokinetics when a polypeptide comprising an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa is administered to a human, the method comprising the steps of administering a polypeptide comprising an Fc variant selectively binding to mouse FcγRII relative to mouse FcγRIII, to a mouse and measuring the pharmacokinetics thereof.

[0264] Specifically, according to a preferred aspect, the method may comprise, for example, the following steps:

(a) obtaining a polypeptide comprising an antigen-binding region binding to a mouse antigen;

(b) preparing a polypeptide comprising the antigen-binding region of the polypeptide obtained in step (a), and the Fc variant of the present invention;

(c) administering the polypeptide prepared in step (b) to a mouse; and

[0265] (d) analogically inferring the pharmacokinetics, in a human, of a polypeptide comprising an antigen-binding region binding to a human counterpart of the mouse antigen, and the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa from the results obtained in step (c) about the pharmacokinetics of the polypeptide of step (b) in the mouse.

[0266] Preferably, the polypeptide comprising an Fc variant selectively binding to human FcγRIIb further comprises an antigen-binding region binding to a human antigen. The human antigen is preferably an antigen capable of serving as a target for the treatment or prevention of the human disease. The antigen-binding region preferably has functions that lead to the treatment or prevention of the human disease through binding to the antigen. In this case, the polypeptide comprising an Fc variant selectively binding to mouse FcγRII has an antigen-binding region binding to a mouse counterpart of the human antigen. In addition, the antigen-binding region preferably has, in mice, functions corresponding to the functions of treating or preventing the human disease by the human antigen-binding region.

[0267] Human FcγRIIb and human FcγRIIa have 93% sequence identity at their extracellular regions. Desirably, the Fc variant selectively binding to human FcγRIIb has higher binding activity against FcγRIIb and lower binding activity against FcγRIIa than those of the Fc region of naturally occurring IgG. In the present specification, the Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa means an Fc region in which a value of the Fc region determined by dividing [KD value for human FcγRIIa] by [KD value for human FcγRIIb] is larger than a value of the Fc region of naturally occurring human IgG determined by dividing [KD value for human FcγRIIa] by [KD value for human FcγRIIb]. Examples of such Fc variants are described in, for example, WO2012/115241 and WO2008/150494. Thus, any of these Fc variants can be used.

[0268] The disease suitable for treatment or prevention using the polypeptide comprising the Fc variant selectively binding to human FcγRIIb is not particularly limited. Preferred examples of the disease include immune inflammatory disease (particularly, autoimmune disease), renal disease, hepatic disease, pulmonary disease, diabetes mellitus, bone disease, blood disease, and cancer disease.

[0269] The polypeptide comprising an antigen-binding region binding to a mouse antigen can be obtained by a method generally known to those skilled in the art, for example, a hybridoma method (Kohler and Milstein, Nature 256, 495 (1975)) or a phage-displayed antibody library method (Clackson et al, Nature 352, 624-628 (1991); and Marks et al, J Mol Biol 222, 581-597 (1991)).

[0270] Also, the polypeptide comprising an antigen-binding region and an Fc region (the Fc region of naturally occurring IgG, the Fc variant of the present invention, etc.) can be prepared by fusing a DNA encoding the antigen-binding region in frame with a DNA encoding the Fc region, and then inserting the fusion product to appropriate expression vectors, which are then transferred to preferred expression cells so that the polypeptide is expressed.

[0271] In the present specification, the “treatment or prevention” means that some pharmacological and/or physiological effect is obtained for a subject having the disease. The “treatment” means the suppression of progression of pathological conditions in a subject already diagnosed with the disease, or the mitigation of these pathological conditions. The “prevention” means the suppression of onset of a disease in a subject yet to be diagnosed with the disease. The strength of such effects may be determined qualitatively from some finding related to the disease or may be determined quantitatively from some index. The index can be selected from, for example, the concentration of a disease marker such as a peptide or a metabolite, disease scores for the numerical rating of symptoms, latency period/incidence, or progression-free survival/survival rate according to the disease, though the index is not particularly limited thereto. When the disease is, for example, asthma, the therapeutic effect can be evaluated on the basis of reduction in plasma IgE concentration or decrease in the number of B cells, mast cells, plasma cells, IgE-producing B cells, or IgE-producing plasma cells.

[0272] In the present specification, the “safety” of the polypeptide means that any adverse event (toxicity or adverse reaction) is not observed in a recipient of the polypeptide, particularly, a mouse or human recipient of the polypeptide. The recipient may be healthy or may have some disease.

[0273] In the present specification, the “toxicity” of the polypeptide means that some adverse event (toxicity or adverse reaction) is observed in a recipient of the polypeptide, particularly, a mouse or human recipient of the polypeptide. The recipient may be healthy or may have some disease.

[0274] In the present specification, the phrase “evaluating the safety” of the polypeptide or “predicting the safety” of the polypeptide means evaluating whether or not some adverse event (toxicity or adverse reaction) is observed in a recipient of the polypeptide, particularly, a mouse or human recipient of the polypeptide. The recipient may be healthy or may have some disease.

[0275] In the present specification, the pharmacokinetics means the behavior of a drug in the body (e.g., the concentration of the drug in blood) after administration of the drug to a subject. Examples thereof include absorption, distribution, metabolism, and excretion. Examples of parameters that exhibit the pharmacokinetics include, but not particularly limited to, half-life, distribution volume, clearance, the rate of absorption/disappearance, and bioavailability.

[0276] The mouse that receives the polypeptide comprising an Fc variant selectively binding to mouse FcγRII may be a wild-type mouse or may be a genetically modified mouse.

[0277] In the present specification, the “mouse antigen” means a molecule that exists as a possible antigen in the living body of a mouse and is capable of serving as a target for the treatment or prevention of the disease. In this context, the mouse antigen is not limited to a mouse-derived molecule as long as the antigen exists in the living body of a mouse. The mouse antigen also includes, for example, molecules derived from bacteria or viruses in mice infected with the bacteria or the viruses. Alternatively, the mouse antigen also includes molecules derived from organisms other than mice, such as proteins expressed from genetically modified mice prepared by the transfer of genes of the organisms (e.g., humans) other than mice.

[0278] In the present specification, the “human counterpart of the mouse antigen” means an antigen having, in humans, functions equivalent to the functions of the mouse antigen in mice. When the mouse antigen is a mouse-derived molecule, its human counterpart means a homolog molecule thereof in humans. When the mouse antigen is a molecule derived from an organism other than the mouse, its human counterpart means a molecule that exhibits, on a human disease, effects equivalent to the effects of the molecule on a mouse disease. When the mouse antigen is a molecule derived from a bacterium or a virus capable of infecting both mice and humans, the mouse antigen is identical to the human antigen. Also, when the mouse antigen is a gene product in a mouse transfected with a human gene, the mouse antigen is identical to the human antigen.

[0279] Examples of the mouse model of a human disease can specifically include, but not limited to: Mrl/lpr mice, NZB/W F1 mice, DNA-induced SLE mouse models, pristane-induced SLE mouse models, and BXSB mice as mouse models of lupus nephritis; IgE-induced mouse models and NC/Nga mice as mouse models of atopic dermatitis; EAE mouse models as mouse models of multiple sclerosis; LPS-induced mouse models as mouse models of sepsis; collagen-induced mouse models, adjuvant-induced mouse models, bacterium-derived cell wall-induced mouse models, NZB/KN mice, Biozzi mice, HTLV-1 transgenic mice, human TNFα transgenic mice, and K/BxN transgenic mice as mouse models of rheumatoid arthritis; NOD mice and STZ mice as mouse models of type 1 diabetes mellitus; db/db mice and KKAy mice as mouse models of type 2 diabetes mellitus; Bleomycin-induced mouse models as mouse models of systemic scleroderma; chronic Thy-1 mouse models as mouse models of chronic kidney disease (CKD); UUO mouse models, I/R mouse models, and NEP25 mice as mouse models of renal fibrosis; β-1,4-galactose transferase-deficient mice as mouse models of IgA nephropathy; CDAHFD mice and high-carbohydrate, high-fat mouse models as mouse models of non-alcoholic steatohepatitis (NASH); and TAA mice and BDL mice as mouse models of hepatic fibrosis.

[0280] Alternatively, a wild-type mouse may be used as the mouse model of a human disease. The wild-type mouse may be subjected to exogenous treatment for developing some disease, and the resulting mouse can serve as the mouse model of a human disease. Examples of the wild-type mouse include, but not limited to, BALB/C and C57BL/6.

[0281] The mouse model used in the present invention is preferably selected from among mouse models having the same disease as that in which the aforementioned mouse antigen can be targeted by the treatment or prevention.

[0282] A polypeptide comprising an antigen-binding region binding to the target antigen selected by the method mentioned above, and an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa is also included in the scope of the present invention.

[0283] A polypeptide comprising the antigen-binding region selected by the method mentioned above, and an Fc variant selectively binding to human FcγRIIb relative to human FcγRIIa is also included in the scope of the present invention.

[0284] In addition, a therapeutic or preventive agent for a human disease, comprising such a polypeptide as an active ingredient is also included in the scope of the present invention. A method for treating or preventing a human disease, comprising administering such a polypeptide to a patient is also included in the scope of the present invention. Use of such a polypeptide in the production of a therapeutic or preventive agent for a human disease is also included in the scope of the present invention. Such a polypeptide for use in the treatment or prevention of a human disease is also included in the scope of the present invention. The human disease is preferably a disease evaluated by the method mentioned above as being suitable for treatment or prevention using the polypeptide.

[0285] The present invention also provides a kit for use in the treatment or prevention of a human disease, comprising such a polypeptide. The human disease is preferably a disease evaluated by the method mentioned above as being suitable for treatment or prevention using the polypeptide. The kit may additionally comprise pharmaceutically acceptable carriers and media, an instruction that provides usage, etc., in a package.

[0286] The polypeptide comprising an Fc variant selectively binding to human FcγRIIb is useful as an active ingredient in an inhibitor of the activation of B cells, mast cells, dendritic cells, and/or basophils. This polypeptide can inhibit the activation of B cells, mast cells, dendritic cells, and/or basophils by the selective action on FcγRIIb without the activation of activating FcγR. The activation of B cells includes proliferation, IgE production, IgM production, IgA production, and the like. According to one aspect, the polypeptide can inhibit the IgE production of B cells through the cross-link of FcγRIIb to IgE, the IgM production of B cells through the cross-link of FcγRIIb to IgM, and the IgA production of B cells through the cross-link of FcγRIIb to IgA. In addition, the polypeptide can exert an inhibitory effect similar to that described above through the direct or indirect cross-link of FcγRIIb to a molecule, such as BCR, CD19, or CD79b, which is expressed on B cells and intracellularly contains an ITAM domain or interacts with an ITAM domain. The activation of mast cells includes proliferation, activation by IgE or the like, degranulation, and the like. According to one aspect, the polypeptide can inhibit the proliferation, activation by IgE or the like, or degranulation of mast cells through the direct or indirect cross-link of FcγRIIb to an IgE receptor molecule, such as FcεRI, DAP12, or CD200R3, which is expressed on mast cells and contains an ITAM domain or interacts with an ITAM domain. The activation of basophils includes proliferation, degranulation, and the like. According to one aspect, the polypeptide can also inhibit the activation, degranulation, or proliferation of basophils through the direct or indirect cross-link of FcγRIIb to a molecule that resides on the cell membrane and intracellularly contains an ITAM domain or interacts with an ITAM domain. The activation of dendritic cells includes proliferation, degranulation, and the like. The polypeptide can also inhibit the activation, degranulation, or proliferation of dendritic cells through the direct or indirect cross-link of FcγRIIb to a molecule that resides on the cell membrane and intracellularly contains an ITAM domain or interacts with an ITAM domain.

[0287] The polypeptide comprising an Fc variant selectively binding to human FcγRIIb is also useful as an active ingredient in a therapeutic or preventive agent for immune inflammatory disease. As mentioned above, the polypeptide can inhibit the activation of B cells, mast cells, dendritic cells, and/or basophils and as such, can treat or prevent immune inflammatory disease through its administration. The “immune inflammatory disease” encompasses, but not limited to: rheumatoid arthritis, autoimmune hepatitis, autoimmune thyroiditis, autoimmune bullous disease, autoimmune adrenocortical inflammation, autoimmune hemolytic anemia, autoimmune thrombocytopenic purpura, megalocytic anemia, autoimmune atrophic gastritis, autoimmune neutropenia, autoimmune orchitis, autoimmune encephalomyelitis, autoimmune receptor disease, autoimmune infertility, chronic active hepatitis, glomerulonephritis, interstitial lung fibrosis, multiple sclerosis, Paget's disease, osteoporosis, multiple myeloma, uveitis, acute and chronic spondylitis, gouty arthritis, inflammatory bowel disease, adult respiratory distress syndrome (ARDS), psoriasis, Crohn's disease, Basedow disease, juvenile diabetes mellitus, Addison's disease, myasthenia gravis, lens-induced uveitis, systemic lupus erythematosus, allergic rhinitis, allergic dermatitis, ulcerative colitis, hypersensitivity, muscle degeneration, cachexia, systemic scleroderma, morphea, Sjogren's syndrome, Behcet's disease, Reiter's syndrome, type I and type II diabetes mellitus, bone resorption, graft-versus-host reaction, ischemia-reperfusion injury, atherosclerosis, brain trauma, cerebral malaria, sepsis, septic shock, toxic shock syndrome, fever, stain-induced myalgias, aplastic anemia, hemolytic anemia, idiopathic thrombocytopenia, Goodpasture's syndrome, Guillain-Barre syndrome, Hashimoto's disease, pemphigus, IgA nephropathy, pollinosis, anti-phospholipid antibody syndrome, polymyositis, Wegener's granulomatosis, arteritis nodosa, mixed connective-tissue disease, fibromyalgia syndrome, asthma, atopic dermatitis, chronic atrophic gastritis, primary biliary cirrhosis, primary sclerosing cholangitis, autoimmune pancreatitis, aortitis syndrome, rapidly progressive glomerulonephritis, megaloblastic anemia, idiopathic thrombocytopenic purpura, primary hypothyroidism, idiopathic Addison's disease, insulin-dependent diabetes mellitus, chronic discoid lupus erythematodes, pemphigoid, herpes gestationis, linear IgA bullous dermatosis, epidermolysis bullosa acquisita, alopecia areata, vitiligo vulgaris, leukoderma acquisitum centrifugum Sutton, Harada's disease, autoimmune optic neuropathy, idiopathic azoospermia, recurrent fetal loss, hypoglycemia, chronic urticaria, ankylosing spondylitis, psoriatic arthritis, enteropathic arthritis, reactive arthritis, spondyloarthropathy, enthesitis, irritable bowel syndrome, chronic fatigue symptom, dermatomyositis, inclusion body myositis, Schmidt's syndrome, Graves' disease, pernicious anemia, lupoid hepatitis, pre-senile dementia, Alzheimer's disease, demyelinating disease, amyotrophic lateral sclerosis, hypoparathyroidism, Dressler's syndrome, Eaton-Lambert syndrome, herpetiform dermatitis, alopecia, progressive systemic sclerosis, CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal motor disturbance, sclerodactylia, and telangiectasis), sarcoidosis, rheumatic fever, erythema multiforme, Cushing's syndrome, transfusion reaction, Hansen's disease, Takayasu arteritis, polymyalgia rheumatica syndrome, temporal arteritis, giant cell arthritis, eczema, lymphomatoid granulomatosis, Kawasaki disease, endocarditis, endomyocardial fibrosis, endophthalmitis, erythroblastosis fetalis, eosinophilic fasciitis, Felty syndrome, Henoch-Shonlein purpura, transplantation rejection, mumps, cardiomyopathy, purulent arthritis, familial Mediterranean fever, Muckle-Wells syndrome, and hyper-IgD syndrome.

[0288] The polypeptide comprising an Fc variant selectively binding to human FcγRIIb is also useful as an active ingredient in a drug treating or preventing autoimmune disease presumably caused by the production of an antibody (autoantibody) against a self-antigen, by inhibiting the production of the autoantibody. Reportedly, use of a molecule comprising a myasthenia gravis self-antigen AchR fused with an antibody Fc domain inhibits the proliferation of B cells expressing AchR-recognizing BCR and enhances the apoptosis thereof (J Neuroimmunol, 227, 35-43, 2010). Use of a fusion protein of an antigen that is recognized by an autoantibody, and the Fc region can inhibit the proliferation of B cells expressing BCR against the self-antigen and induce the apoptosis thereof by cross-linking FcγRIIb to BCR in the B cells expressing BCR against the self-antigen. Such autoimmune disease includes, but not limited to, Guillain-Barre syndrome, myasthenia gravis, chronic atrophic gastritis, autoimmune hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis, autoimmune pancreatitis, aortitis syndrome, Goodpasture's syndrome, rapidly progressive glomerulonephritis, megaloblastic anemia, autoimmune hemolytic anemia, autoimmune neutropenia, idiopathic thrombocytopenic purpura, Basedow disease, Hashimoto's disease, primary hypothyroidism, idiopathic Addison's disease, insulin-dependent diabetes mellitus, chronic discoid lupus erythematodes, morphea, pemphigus, pemphigoid, herpes gestationis, linear IgA bullous dermatosis, epidermolysis bullosa acquisita, alopecia areata, vitiligo vulgaris, leukoderma acquisitum centrifugum Sutton, Harada's disease, autoimmune optic neuropathy, idiopathic azoospermia, recurrent fetal loss, type II diabetes mellitus, hypoglycemia, and chronic urticaria.

[0289] The polypeptide comprising an Fc variant selectively binding to human FcγRIIb is also useful as an active ingredient in a therapeutic agent for a disease with deficiency in a protein necessary for organisms. For the disease with deficiency in a protein necessary for organisms, replacement therapy involving administering the protein as a drug to a patient is used. Since the patient, however, is originally deficient in this protein, the protein supplied from the outside is recognized as a foreign substance, resulting in the production of an antibody against the protein. Consequently, the protein is easily removed to reduce its drug effect. Use of a fusion protein of such a protein and the Fc region can inhibit the production of an antibody against the protein by cross-linking FcγRIIb to BCR on B cells that recognize the protein. The protein to be supplied includes Factor VIII, Factor IX, TPO, EPO, α-iduronidase, iduronate sulfatase, type A heparan N-sulfatase, type B α-N-acetylglucosaminidase, type C acetyl CoA:α-glucosaminidase acetyltransferase, type D N-acetylglucosamine 6-sulfatase, galactose 6-sulfatase, N-acetylgalactosamine 4-sulfatase, β-glucuronidase, α-galactosidase, acidic α-galactosidase, and glucocerebrosidase. The disease to be treated by the replacement therapy of such a protein includes, but not limited to, hemophilia, idiopathic thrombocytopenic purpura, renal anemia, lysosomal disease (mucopolysaccharidosis, Fabry's disease, Pompe's disease, and Gaucher's disease), and the like.

[0290] The polypeptide comprising an Fc variant selectively binding to human FcγRIIb is also useful as an active ingredient in an antiviral agent. An antibody that is directed to a virus and comprises the Fc region can inhibit antibody-dependent enhancement found in an antibody against the virus. The antibody-dependent enhancement refers to the phenomenon in which a virus is englobed via activating FcγR by use of a neutralizing antibody against the virus to infect FcγR-expressing cells, thereby spread the infection. The FcγRIIb binding of a neutralizing antibody against dengue virus has been reported to play an important role in inhibiting the antibody-dependent enhancement (Proc Natl Acad Sci USA, 108, 12479-12484, 2011). An immune complex of dengue virus formed by a neutralizing antibody against the dengue virus cross-links FcγRIIb and thereby inhibits englobement mediated by FcγR, resulting in the inhibition of the antibody-dependent enhancement. The virus includes, but not limited to, dengue virus (DENV1, DENV2, and DENV4) and HIV.

[0291] The polypeptide comprising an Fc variant selectively binding to human FcγRIIb is also useful as an active ingredient in a preventive or therapeutic agent for arteriosclerosis. An antibody that is directed to oxidized LDL, which is responsible for arteriosclerosis, and comprises the Fc region can prevent FcγRIIa-dependent inflammatory cell adhesion. The anti-oxidized LDL antibody inhibits the interaction between oxidized LDL and CD36. The anti-oxidized LDL antibody has been reported to bind to endothelial cells so that its Fc domain is recognized by monocytes in an FcγRIIa- or FcγRI-dependent manner for adhesion (Immunol Lett, 108, 52-61, 2007). The antibody comprising the Fc region can be used as such an antibody to thereby probably inhibit FcγRIIa-dependent binding and inhibit monocyte adhesion through inhibitory signals mediated by FcγRIIb.

[0292] The polypeptide comprising an Fc variant selectively binding to human FcγRIIb is also useful as an active ingredient in a therapeutic or preventive agent for cancer. Enhanced binding to FcγRIIb is known to enhance the agonistic activity of an agonist antibody and also enhance an antitumor effect based on the agonistic activity. Thus, an agonist antibody comprising the Fc region is useful in the treatment or prevention of cancer. The Fc region enhances the agonistic activity of agonist antibodies against the TNF receptor family including Aliases, CD120a, CD120b, Lymphotoxin β receptor, CD134, CD40, FAS, TNFRSF6B, CD27, CD30, CD137, TNFRSF10A, TNFRSF10B, TNFRSF10C, TNFRSF10D, RANK, Osteoprotegerin, TNFRSF12A, TNFRSF13B, TNFRSF13C, TNFRSF14, Nerve growth factor receptor, TNFRSF17, TNFRSF18, TNFRSF19, TNFRSF21, TNFRSF25, and Ectodysplasin A2 receptor. The Fc region also enhances the agonistic activity of other agonist antibodies. The cancer encompasses, but not limited to: lung cancer (including small-cell lung cancer, non-small-cell lung cancer, lung adenocarcinoma, and lung squamous cell carcinoma), large bowel cancer, rectal cancer, colon cancer, breast cancer, liver cancer, stomach cancer, pancreatic cancer, kidney cancer, prostate cancer, ovary cancer, thyroid gland cancer, bile duct cancer, peritoneal cancer, mesothelioma, squamous cell cancer, uterine cervix cancer, uterine body cancer, bladder cancer, esophagus cancer, head and neck cancer, nasopharyngeal cancer, salivary gland tumor, thymoma, skin cancer, basal cell tumor, malignant melanoma, anus cancer, penis cancer, testis cancer, Wilms's tumor, acute myeloid leukemia (including acute myeloleukemia, acute myeloblastic leukemia, acute promyelocytic leukemia, acute myelomonocytic leukemia, and acute monocytic leukemia), chronic myeloid leukemia, acute lymphoid leukemia, chronic lymphoid leukemia, Hodgkin's lymphoma, non-Hodgkin's lymphoma (Burkitt's lymphoma, chronic lymphocytic leukemia, mycosis fungoides, mantle cell lymphoma, follicular lymphoma, diffuse large-cell lymphoma, marginal zone lymphoma, hairy cell leukemia, plasmacytoma, peripheral T-cell lymphoma, and adult T-cell leukemia/lymphoma), Langerhans' cell histiocytosis, multiple myeloma, myelodysplastic syndrome, brain tumor (including glioma, astroglioma, glioblastoma, meningioma, and ependymoma), neuroblastoma, retinoblastoma, osteosarcoma, Kaposi's sarcoma, Ewing's sarcoma, angiosarcoma, and hemangiopericytoma.

[0293] The three-letter codes and one-letter codes of the amino acids used herein are defined as follows:

• [0294] Alanine: Ala: A
• [0295] Arginine: Arg: R
• [0296] Asparagine: Asn: N
• [0297] Aspartic acid: Asp: D
• [0298] Cysteine: Cys: C
• [0299] Glutamine: Gln: Q
• [0300] Glutamic acid: Glu: E
• [0301] Glycine: Gly: G
• [0302] Histidine: His: H
• [0303] Isoleucine: Ile: I
• [0304] Leucine: Leu: L
• [0305] Lysine: Lys: K
• [0306] Methionine: Met: M
• [0307] Phenylalanine: Phe: F
• [0308] Proline: Pro: P
• [0309] Serine: Ser: S
• [0310] Threonine: Thr: T
• [0311] Tryptophan: Trp: W
• [0312] Tyrosine: Tyr: Y
• [0313] Valine: Val: V

[0314] All literatures cited herein are incorporated herein by reference.

[0315] The present invention will be further illustrated with reference to Examples below. However, the present invention is not intended to be limited by Examples below.

[0316] There has been no report on an Fc variant having selectively enhanced binding activity against mouse FcγRII (in the present specification, also referred to as mFcγRII or mFcgRII). Meanwhile, in Patent Literature 5 (US2009/0136485), Fc variants having enhanced binding activity against human FcγRIIb (in the present specification, also referred to as hFcγRIIb or hFcgRIIb) were evaluated for their binding activities against mFcγRII. These Fc variants were prepared on the basis of human IgG1. As seen from the results of this evaluation, an Fc variant whose binding activity against mFcγRII was most strongly enhanced was Fc with introduced alterations that substituted Ser 239 (EU numbering) by Asp, Lys 326 (EU numbering) by Asp, and Leu 328 (EU numbering) by Tyr, and the mFcγRII-binding activity was enhanced by approximately 130 times compared with that of human IgG1. Nonetheless, the mFcγRII selectivity of the Fc variant was still unknown, because the literature makes no mention about data on binding activity against mouse FcγRIII (in the present specification, also referred to as mFcγRIII or mFcgRIII).

[0317] Thus, in order to evaluate the selectivity, 8 Fc variants were selected mainly on the basis of strongly enhanced binding to mFcγRII from among the human IgG1-templated Fc variants described in Patent Literature 5 (US2009/0136485). Variants having these Fc variants were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200. The antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab. The antibody H chain constant region used was each of the aforementioned 8 Fc variants prepared by altering human IgG1 hIgG1 (SEQ ID NO: 3) as a template. In this context, the introduced alterations involved 10 types of alterations (alteration that substituted Leu 234 (EU numbering) by Trp: L234W, alteration that substituted Ser 239 (EU numbering) by Asp: S239D, alteration that substituted Ser 267 (EU numbering) by Ala: S267A, alteration that substituted Ser 267 (EU numbering) by Glu: S267E, alteration that substituted His 268 (EU numbering) by Asp: H268D, alteration that substituted Lys 326 (EU numbering) by Asp: K326D, alteration that substituted Ala 327 (EU numbering) by Asp: A327D, alteration that substituted Leu 328 (EU numbering) by Phe: L328F, alteration that substituted Leu 328 (EU numbering) by Trp: L328W, and alteration that substituted Leu 328 (EU numbering) by Tyr: L328Y). A variant H237-mIgG1/MRAL-k0 comprised of H237-mIgG1 (SEQ ID NO: 7) having a mouse IgG1 H chain constant region (mIgG1, SEQ ID NO: 4) and MRAL-k0 was used as a control.

[0318] Table 1 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the evaluated variants with the values of H237-mIgG1/MRAL-k0 as 1. “Name” in the table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Table 1 were alterations introduced to the H chain constant region (SEQ ID NO: 3) of human IgG1 (hIgG1).

[0319] A value I/A determined by dividing a KD value for mFcγRIII by a KD value for mFcγRII was used as an index for evaluating selectivity for mFcγRII. This index exhibits a larger value when the KD value for mFcγRII is smaller or when the KD value for mFcγRIII is larger. This means that an variant exhibiting a larger I/A value has higher selectivity for mFcγRII relative to mFcγRIII.

[0320]

TABLE 1
		Relative	Relative		Relative
		mFcγRII-	mFcγRIII-		I/A
		binding	binding		(mFcγRII
		activity	activity	I/A	selectivity)
Name	Introduced	(mIgG1 =	(mIgG1 =	(mFcγRII	(mIgG1 =
(CH)	alteration	1)	1)	selectivity)	1)
mIgG1	none	1.0	1.0	1.34	1.00
FS130	S267E	0.3	0.3	1.36	1.01
P253	S267E/L328F	1.0	4.6	0.29	0.21
FS131	L234W/S239D/	144.3	33.2	5.83	4.34
	L328Y
FS132	S239D/A327D/	96.7	41.8	3.10	2.31
	L328Y
FS133	S239D/H268D/	161.7	86.5	2.51	1.87
	L328W
FS134	S239D/H268D/	58.2	20.8	3.75	2.80
	L328Y
F616	S239D/K326D/	186.5	50.1	5.00	3.72
	L328Y
FS135	S239D/S267A/	137.9	34.4	5.38	4.01
	L328Y
(Relative binding activity: value determined by dividing the KD value of H237-mIgG1/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR,
Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-mIgG1/MRAL-k0)

[0321] As seen from the results of Table 1, some of the hIgG1-templated Fc variants described in Patent Literature 5 (US2009/0136485) had relative mFcγRII-binding activity enhanced by approximately 190 times compared with that of mIgG1, but exhibited approximately 4-fold relative I/A which indicated weak mFcγRII selectivity.

[0322] In short, there has been no report on an Fc variant having enhanced binding to mFcγRII with sufficient selectivity relative to mFcγRIII. The results described above demonstrated that an Fc variant having enhanced mFcγRII-selective binding with higher selectivity is necessary for more accurately testing the effects of an Fc variant with selectively enhanced FcγRII binding in mouse models of various diseases including autoimmune disease.

[0323] Naturally occurring mouse IgG1 (in the present specification, also referred to as mIgG1) exhibits binding only to mFcγRII and mFcγRIII among 4 types of mouse FcγR (in the present specification, also referred to as mFcγR or mFcgR) without binding to mouse FcγRI (in the present specification, also referred to as mFcγRI or mFcgRI) and mouse FcγRIV (in the present specification, also referred to as mFcγRIV or mFcgRIV) (Science 2005, 310, 1510-1512). For this reason, the present inventors believed that an Fc variant with selectively enhanced binding to mFcγRII could be prepared by conferring selectivity for mFcγRII relative to mFcγRIII with mIgG1 as a template.

[0324] In order to find an alteration to selectively enhance binding activity against inhibitory mFcγR (i.e., mFcγRII) relative to activating mFcγR, particularly, mFcγRIII, compared with that of mIgG1, the mIgG1 antibody was mutated and then comprehensively analyzed for its binding to each mFcγR.

[0325] In the evaluation below, the antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody H chain constant region used was mIgG1 (SEQ ID NO: 4). The resulting H chain was designated as H237-mIgG1 (SEQ ID NO: 7). Likewise, the antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab.

[0326] FIG. 1 shows results of comparing the sequences of mFcγRII (NCBI Reference Sequence: NP_034317.1) and mFcγRIII (NCBI Reference Sequence: NP_034318.2). FIG. 1 demonstrated that mFcγRII and mFcγRIII differ only by two residues at their sites predicted to interact with IgG Fc.

[0327] For preparing an Fc variant with selectively enhanced binding activity against mFcγRII relative to mFcγRIII, it is necessary to distinguish these two residues differing therebetween. In addition, three-dimensional structural information about mFcγRII and mFcγRIII remained to be gained. Thus, the rational design of the Fc variant of interest seemed to be difficult. Accordingly, H237-mIgG1/MRAL-k0 having the H chain constant region mIgG1 was used as a template to substitute each of the amino acids considered to participate in binding to mFcγR and their neighboring amino acids (EU numbering positions 230 to 232, 236 to 241, 265 to 268, 296, 298, and 300) by 18 types of amino acids except for the original amino acid and Cys. The resulting Fc variants were designated as mIgG1 variants. The mIgG1 variants were expressed and purified by the method of Reference Example 1 and comprehensively evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore 4000.

[0328] The results of analyzing interaction with each mFcγR were plotted according to the following method: the KD value of unmutated H237-mIgG1/MRAL-k0 for mFcγR was divided by the KD value of each mIgG1 variant for mFcγR, and the obtained value was used as an index for the relative binding activity of the mIgG1 variant for each mFcγR. The horizontal axis indicates the value of the relative binding activity of each mIgG1 variant for mFcγRIII, and the vertical axis indicates the value of the relative binding activity of each mIgG1 variant for mFcγRII (FIG. 2).

[0329] From the results shown in FIG. 2, some alterations were found to enhance relative mFcγRII-binding activity over relative mFcγRIII-binding activity, i.e., to improve selectivity for mFcγRII. In the comprehensive analysis of the mIgG1 variants for their binding to mFcγR, the effects of alterations that enhanced relative mFcγRII-binding activity by 1.1 times or more and improved relative I/A (mFcγRII selectivity) by 1.1 times or more were summarized in Table 2. “Name” in the table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Table 2 were alterations introduced to the H chain constant region (SEQ ID NO: 4) of mouse IgG1 (mIgG1).

[0330] Among a total of 288 variants evaluated, only 39 variants satisfied the criteria. The highest relative I/A (mFcγRII selectivity) was 4.51 times. Among them, only 26 alterations (9 alterable sites) enhanced relative mFcγRII-binding activity by 1.4 times or more and improved relative I/A (mFcγRII selectivity) by 1.2 times or more, and these alterations were considered more advantageous. This implied that it is very difficult to enhance mFcγRII-binding activity while conferring selectivity for mFcγRII relative to mFcγRIII.

[0331]

TABLE 2
		Relative	Relative
		mFcγRII-	mFcγRIII-	Relative I/A
		binding	binding	(mFcγRII
Name	Introduced	activity	activity	selectivity)
(CH)	alteration	(mIgG1 = 1)	(mIgG1 = 1)	(mIgG1 = 1)
MB002	T230D	2.72	1.47	1.85
MB003	T230E	5.06	1.51	3.35
MB013	T230Q	1.20	1.07	1.12
MB016	T230V	1.15	1.00	1.15
MB019	V231A	2.70	1.44	1.87
MB020	V231D	7.97	2.84	2.80
MB021	V231E	8.52	3.58	2.38
MB025	V231I	1.19	1.06	1.13
MB027	V231L	1.88	1.55	1.21
MB028	V231M	1.83	1.42	1.29
MB030	V231P	5.26	2.27	2.31
MB031	V231Q	1.99	1.48	1.34
MB034	V231T	1.25	1.12	1.11
MB037	P232A	1.54	1.22	1.26
MB038	P232D	3.15	1.37	2.30
MB039	P232E	3.27	1.29	2.54
MB040	P232F	1.47	1.17	1.26
MB045	P232L	1.20	0.90	1.34
MB052	P232V	1.36	1.20	1.14
MB053	P232W	1.36	1.02	1.33
MB054	P232Y	1.75	1.11	1.58
MB093	S238E	2.09	0.56	3.71
MB102	S238P	2.62	2.37	1.11
MB103	S238Q	1.27	1.05	1.21
MB110	S239D	15.07	4.45	3.39
MB111	S239E	5.01	1.11	4.51
MB118	S239M	1.74	0.99	1.76
MB121	S239Q	1.48	0.94	1.58
MB126	S239Y	1.58	0.94	1.69
MB129	V240E	6.19	2.42	2.55
MB132	V240H	2.12	1.39	1.52
MB139	V240Q	1.54	1.20	1.28
MB143	V240W	7.42	6.32	1.17
MB161	F241W	1.47	1.13	1.30
MB162	F241Y	1.40	1.20	1.17
MB188	I266L	1.16	1.00	1.15
MB199	S267A	1.48	1.19	1.24
MB251	F296W	1.49	1.23	1.22
MB261	S298L	2.11	1.81	1.17
(Relative binding activity: value determined by dividing the KD value of H237-mIgG1/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR,
Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-mIgG1/MRAL-k0)

[0332] Of the alterations found in Example 2 to selectively enhance binding to mFcγRII, the variant H237-MB110/MRAL-k0 with the introduced alteration that substituted Ser 239 (EU numbering) by Asp had the highest enhancement in relative mFcγRII-binding activity (15.1 times the mFcγRII-binding activity of H237-mIgG1/MRAL-k0) and also exhibited 3.4-fold relative I/A (mFcγRII selectivity) compared with that of H237-mIgG1/MRAL-k0. Thus, on the basis of this variant, one or more alteration(s) to selectively enhance mFcγRII-binding activity was further introduced thereto to evaluate the effects of combined alterations. For the study on the effects of combinations, 8 types of alterations (alteration that substituted Tyr 230 (EU numbering) by Glu: T230E, alteration that substituted Val 231 (EU numbering) by Ala: V231A, alteration that substituted Val 231 (EU numbering) by Asp: V231D, alteration that substituted Pro 232 (EU numbering) by Glu: P232E, alteration that substituted Ser 238 (EU numbering) by Glu: S238E, alteration that substituted Val 240 (EU numbering) by Glu: V240E, alteration that substituted Val 240 (EU numbering) by His: V240H, and alteration that substituted Ser 267 (EU numbering) by Ala: S267A) were selected from Table 1 and introduced as the alterations.

[0333] The antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab. H237-MB110/MRAL-k0 with the S239D alteration introduced in H237-mIgG1/MRAL-k0 was used as a template to introduce combinations of the alterations. The resulting variant group was designated as MB110 variants. These variants were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200.

[0334] The results of analyzing interaction with each mFcγR were plotted according to the following method: the KD value of unmutated H237-mIgG1/MRAL-k0 for mFcγR was divided by the KD value of H237-MB110/MRAL-k0 or each MB110 variant for mFcγR, and the obtained value was used as an index for the relative binding activity for each mFcγR. The horizontal axis indicates the value of the relative binding activity of H237-MB110/MRAL-k0 or each MB110 variant for mFcγRIII, and the vertical axis indicates the value of the relative binding activity of H237-MB110/MRAL-k0 or each MB110 variant for mFcγRII (FIG. 3).

[0335] Table 3 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the evaluated MB110 variants with the values of H237-mIgG1/MRAL-k0 as 1. Table 4 shows results with the binding activity and I/A (mFcγRII selectivity) of H237-MB110/MRAL-k0 having no additional alteration as 1. “Name” in each table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Tables 3 and 4 were alterations introduced to the H chain constant region (SEQ ID NO: 4) of mouse IgG1 (mIgG1).

[0336]

TABLE 3
		Relative	Relative
		mFcγRII-	mFcγRIII-	Relative I/A
		binding	binding	(mFcγRII
Name		activity	activity	selectivity)
(CH)	Introduced alteration	(mIgG1 = 1)	(mIgG1 = 1)	(mIgG1 = 1)
MB110	S239D	12.3	4.0	3.1
MB289	T230E/S239D	43.8	4.9	8.9
MB290	V231A/S239D	26.5	5.5	4.8
MB291	V231D/S239D	42.6	6.7	6.4
MB292	P232E/S239D	34.6	4.1	8.4
MB293	S238E/S239D	39.9	4.1	9.9
MB294	S239D/V240E	7.6	1.9	4.0
MB295	S239D/V240H	7.6	1.7	4.5
MB296	S239D/S267A	21.0	5.6	3.8
MB299	T230E/V231A/S239D	60.8	6.5	9.4
MB300	T230E/V231D/S239D	52.3	5.7	9.2
MB301	T230E/P232E/S239D	43.2	4.6	9.3
MB302	T230E/S238E/S239D	53.7	4.5	12.0
MB303	T230E/S239D/V240E	7.8	1.3	6.1
MB304	T230E/S239D/V240H	13.7	2.0	6.8
MB305	V231A/P232E/S239D	26.0	3.8	6.9
MB306	V231A/S238E/S239D	65.8	4.2	15.7
MB307	V231A/S239DN240E	11.3	2.2	5.1
MB308	V231A/S239D/V240H	26.3	2.7	9.8
MB309	V231D/P232E/S239D	27.9	3.9	7.2
MB310	V231D/S238E/S239D	38.8	3.8	10.1
MB311	V231D/S239D/V240E	17.6	2.1	8.3
MB312	V231D/S239D/V240H	55.4	3.5	16.0
MB313	P232E/S238E/S239D	40.1	4.0	10.1
MB314	P232E/S239D/V240E	7.1	1.1	6.5
MB315	P232E/S239D/V240H	5.9	0.8	7.3
MB316	S238E/S239D/V240E	7.4	1.2	6.0
MB317	S238E/S239D/V240H	6.0	0.5	12.2
MB318	T230E/P232E/S238E/S239D	40.5	3.9	10.5
MB319	T230E/V231A/P232E/S238E/S239D	50.0	3.6	14.1
MB320	T230E/V231A/P232E/S238E/S239D/V240E	3.2	0.4	7.5
MB321	T230E/V231A/P232E/S238E/S239D/V240H	3.5	0.2	17.9
MB322	T230E/V231D/P232E/S238E/S239D	9.2	1.3	7.3
MB323	T230E/V231D/P232E/S238E/S239D/V240E	1.7	0.1	15.0
MB324	T230E/V231D/P232E/S238E/S239D/V240H	1.1	0.1	9.2
MB325	T230E/P232E/S238E/S239D/V240E	4.7	0.6	7.7
MB326	T230E/P232E/S238E/S239D/V240H	4.0	0.2	17.7
MB337	T230E/V231A/S238E/S239D	73.4	4.6	16.0
MB338	T230E/V231D/S238E/S239D	42.2	2.6	16.5
(Relative binding activity: value determined by dividing the KD value of H237-mIgG1/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR, Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-mIgG1/MRAL-k0)

[0337]

TABLE 4
		Relative	Relative
		mFcγRII-	mFcγRIII-	Relative I/A
		binding	binding	(mFcγRII
Name		activity	activity	selectivity)
(CH)	Introduced alteration	(MB110 = 1)	(MB110 = 1)	(MB110 = 1)
MB110	S239D	1.00	1.00	1.00
MB289	T230E/S239D	3.57	1.23	2.87
MB290	V231A/S239D	2.16	1.37	1.55
MB291	V231D/S239D	3.47	1.66	2.06
MB292	P232E/S239D	2.82	1.02	2.71
MB293	S238E/S239D	3.25	1.01	3.19
MB294	S239D/V240E	0.62	0.47	1.29
MB295	S239D/V240H	0.62	0.42	1.45
MB296	S239D/S267A	1.71	1.39	1.23
MB299	T230E/V231A/S239D	4.96	1.61	3.03
MB300	T230E/V231D/S239D	4.25	1.41	2.97
MB301	T230E/P232E/S239D	3.52	1.16	3.00
MB302	T230E/S238E/S239D	4.37	1.11	3.87
MB303	T230E/S239D/V240E	0.64	0.32	1.97
MB304	T230E/S239D/V240H	1.11	0.50	2.19
MB305	V231A/P232E/S239D	2.12	0.94	2.23
MB306	V231A/S238E/S239D	5.36	1.05	5.06
MB307	V231A/S239D/V240E	0.92	0.55	1.65
MB308	V231A/S239D/V240H	2.14	0.67	3.16
MB309	V231D/P232E/S239D	2.27	0.96	2.32
MB310	V231D/S238E/S239D	3.16	0.96	3.26
MB311	V231D/S239D/V240E	1.43	0.52	2.68
MB312	V231D/S239D/V240H	4.51	0.87	5.16
MB313	P232E/S238E/S239D	3.27	0.99	3.26
MB314	P232E/S239D/V240E	0.58	0.27	2.10
MB315	P232E/S239D/V240H	0.48	0.20	2.35
MB316	S238E/S239D/V240E	0.61	0.31	1.94
MB317	8238E/S239D/V240H	0.49	0.12	3.94
MB318	T230E/P232E/S238E/S239D	3.29	0.96	3.39
MB319	T230E/V231A/P232E/S238E/S239D	4.07	0.89	4.55
MB320	T230E/V231A/P232E/S238E/S239D/V240E	0.26	0.11	2.42
MB321	T230E/V231A/P232E/S238E/S239D/V240H	0.28	0.05	5.77
MB322	T230E/V231D/P232E/S238E/S239D	0.75	0.31	2.35
MB323	T230E/V231D/P232E/S238E/S239D/V240E	0.13	0.03	4.84
MB324	T230E/V231D/P232E/S238E/S239D/V240H	0.09	0.03	2.97
MB325	T230E/P232E/S238E/S239D/V240E	0.38	0.15	2.48
MB326	T230E/P232E/S238E/S239D/V240H	0.33	0.06	5.71
MB337	T230E/V231A/S238E/S239D	5.98	1.15	5.16
MB338	T230E/V231D/S238E/S239D	3.44	0.64	5.32
(Relative binding activity: value determined by dividing the KD value of H237-MB110/MRAL-k0 for each mFcγR by the KD value of each MB110 variant for each mFcγR, Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each MB110 variant by I/A of H237-MB110/MRAL-k0)

[0338] First, as a result of introducing any one of the aforementioned 8 alterations to H237-MB110/MRAL-k0, 6 (T230E, V231A, V231D, P232E, S238E, and S267A) of the introduced alterations were found to enhance binding activity against mFcγRII while maintaining or improving I/A (mFcγRII selectivity) (Tables 3 and 4). Next, of these 6 alterations, 5 alterations (T230E, V231A, V231D, P232E, and S238E) effective for enhancing relative mFcγRII-binding activity by 2 times or more with the value of H237-MB110/MRAL-k0 as 1 were introduced in various combinations. As a result, further improvement in I/A (mFcγRII selectivity) and further enhancement in binding activity against mFcγRII were observed. All of the variants with 3 or more alterations introduced in H237-mIgG1/MRAL-k0, evaluated in this study produced results superior to the relative I/A (mFcγRII selectivity) of the antibodies having the conventional Fc variants shown in Table 1 of Example 1. Among them, the variant (H237-MB337/MRAL-k0) with 4 alterations, i.e., T230E, V231A, S238E, and S239D, introduced in H237-mIgG/MRAL-k0 had relative mFcγRII-binding activity enhanced by 73.4 times and relative I/A (mFcγRII selectivity) improved by 16 times compared with those of mIgG1 (Tables 3 and 4).

[0339] On the other hand, the results of Tables 3 and 4 revealed that the combination of two or more alterations produced many changes in mFcγRII-binding activity and I/A (mFcγRII selectivity) that were unexpectable from the comprehensive analysis results of the H237-mIgG1/MRAL-k0-templated point-mutation variants. For example, the introduction of P232E alteration to H237-MB110/MRAL-k0 enhanced mFcγRII-binding activity by 2.8 times compared with that before its introduction, whereas the variant H237-MB305/MRAL-k0 with P232E alteration further introduced in the variant H237-MB290/MRAL-k0 with V231A alteration introduced in H237-MB110/MRAL-k0 exhibited no enhancement in mFcγRII-binding activity compared with that before the introduction of P232E alteration. Likewise, the introduction of V231D alteration to H237-MB110/MRAL-k0 enhanced mFcγRII-binding activity by 3.5 times compared with that before its introduction, whereas the variant H237-MB338/MRAL-k0 with V231D alteration further introduced in the variant H237-MB302/MRAL-k0 with T230E and S238E alterations introduced in H237-MB110/MRAL-k0 was shown to reduce mFcγRII-binding activity to approximately 0.8 times compared with that before the introduction of V231D alteration.

[0340] As mentioned above, the further combinations of the alterations did not produce the expected effects, presumably because the alterations are introduced at adjacent positions and therefore influence each other on the same H chain and also because the alterations are introduced at positions in the lower hinge region of an antibody, which correspond to the interacting interface between the antibody and mFcγR as well as the interacting interface between the Fc chains of this antibody, and therefore influence each other even on different H chains. For these reasons, it was considered difficult to predict the effects of combined alterations from the comprehensive analysis results of the H237-mIgG1/MRAL-k0-templated point-mutation variants.

[0341] As shown in Example 3, the further combinations of the alterations did not produce the effects expected from the comprehensive analysis results of the H237-mIgG1/MRAL-k0-templated point-mutation variants, in some cases. Thus, it was difficult to predict combinations of alterations aimed at further enhancement in mFcγRII-binding activity, from the results obtained in Examples 2 and 3. Accordingly, as mentioned above, the adjacent amino acids at EU numbering positions 230, 231, and 232 to be altered in the lower hinge region were each substituted by an amino acid having a characteristic property, such as a negatively charged amino acid, a positively charged amino acid, a highly hydrophilic amino acid, an amino acid having a characteristic side chain length, or an amino acid having an aromatic ring, and variously combined to thereby search for a combination of alterations more suitable for enhancement in mFcγRII-binding activity and improvement in I/A (mFcγRII selectivity).

[0342] As in Examples 2 and 3, the antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab. S238E and S239D alterations were introduced to H237-mIgG1/MRAL-k0, and combinations of the amino acids at EU numbering positions 230, 231, and 232 were then studied. These variants were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200.

[0343] The results of analyzing interaction with each mFcγR were plotted according to the following method: the KD value of unmutated H237-mIgG1/MRAL-k0 for mFcγR was divided by the KD value of each variant for mFcγR, and the obtained value was used as an index for the relative binding activity for each mFcγR. The horizontal axis indicates the value of the relative binding activity of each variant for mFcγRIII, and the vertical axis indicates the value of the relative binding activity of each variant for mFcγRII (FIG. 4).

[0344] Among the variants evaluated in this study, only the variant having T230E alteration was plotted according to the method given below in order to evaluate effects brought about by the substitution of amino acids at EU numbering positions 231 and 232. These variants had 3 alterations (T230E/S238E/S239D) in common and differed only in the amino acids at EU numbering positions 231 and 232. In the drawing, the lower row of the horizontal axis represents the type of the amino acid at EU numbering position 232 in each variant, and the upper row of the horizontal axis represents the type of the amino acid at EU numbering position 231 in each variant. The left vertical axis indicates the KD value of each variant for mFcγRII (p circle) and mFcγRIII (filled rhombus), and the right vertical axis indicates relative I/A (mFcγRII selectivity) (open circle) in comparison with mIgG1 (FIG. 5). Since the left vertical axis is indicated by inverted log scale, more enhanced binding activity is shown at an upper position.

[0345] In the foregoing, the P232E alteration that exhibited the highest enhancement in mFcγRII-binding activity and improvement in I/A (mFcγRII selectivity) in the results of Table 2 of Example 2 was used for the amino acid at EU numbering position 232. The results of FIG. 5, however, showed that variants with the amino acid substituted by each of 5 amino acids (Ala, Asn, Pro, Trp, and Tyr) newly studied in this Example produced more favorable results about mFcγRII-binding activity and I/A (mFcγRII selectivity) than those of the P232E variant used above. Particularly, the substitution of the amino acid at EU numbering position 232 by an aromatic amino acid such as Trp or Tyr generally exhibited strong mFcγRII-binding activity, regardless of the type of the amino acid at EU numbering position 231. In this respect, enhancement in binding to mFcγRIII was also observed, but remained at a low level, resulting in relative I/A (mFcγRII selectivity) as high as 15 times or more. When the amino acid at EU numbering position 232 was substituted by an amino acid other than the aromatic amino acid such as Trp or Tyr, the substitution of Val 231 (EU numbering) by Pro was shown to remarkably enhance binding to mFcγRII, but weakly enhance binding to mFcγRIII, and to greatly improve mFcγRII selectivity. These results implied that the alteration that substitutes the amino acid at EU numbering position 232 by an aromatic amino acid such as Trp or Tyr and the alteration that substitutes Val 231 (EU numbering) by Pro are preferred from the viewpoint of enhancing binding activity against mFcγRII and improving I/A (mFcγRII selectivity).

[0346] Table 5 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the variants evaluated in this study with the values of H237-mIgG1/MRAL-k0 as 1. “Name” in the table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Table 5 were alterations introduced to the H chain constant region (SEQ ID NO: 4) of mouse IgG1 (mIgG1).

[0347]

TABLE 5
		Relative	Relative	Relative
		mFcγRII-	mFcγRIII-	I/A
		binding	binding	(mFcγRII
Name		activity	activity	selectivity)
(CH)	Introduced alteration	(mIgG1 = 1)	(mIgG1 = 1)	(mIgG1 = 1)
MB302	T230E/S238E/S239D	53.7	4.5	12.0
MB306	V231A/S238E/S239D	65.8	4.2	15.7
MB310	V231D/S238E/S239D	38.8	3.8	10.1
MB313	P232E/S238E/S239D	40.1	4.0	10.1
MB318	T230E/P232E/S238E/S239D	40.5	3.9	10.5
MB319	T230E/V231A/P232E/S238E/S239D	50.0	3.6	14.1
MB322	T230E/V231D/P232E/S238E/S239D	9.2	1.3	7.3
MB337	T230E/V231A/S238E/S239D	73.4	4.6	16.0
MB338	T230E/V231D/S238E/S239D	42.2	2.6	16.5
MB339	T230E/P232W/S238E/S239D	196.8	11.6	17.0
MB340	T230E/V231A/P232W/S238E/S239D	220.7	9.9	22.4
MB341	T230E/V231D/P232W/S238E/S239D	268.5	11.5	23.4
MB358	T230E/V231A/P232A/S238E/S239D	113.8	4.1	27.7
MB367	T230E/V231A/P232N/S238E/S239D	158.6	6.2	25.6
MB373	T230E/V231A/P232Y/S238E/S239D	390.4	15.5	25.2
MB377	T230E/P232A/S238E/S239D	127.0	6.0	21.3
MB378	T230E/P232N/S238E/S239D	172.4	9.3	18.6
MB379	T230E/P232Y/S238E/S239D	273.4	12.2	22.5
MB380	T230E/V231D/P232A/S238E/S239D	78.1	4.2	18.7
MB381	T230E/V231D/P232N/S238E/S239D	93.5	5.7	16.5
MB382	T230E/V231D/P232Y/S238E/S239D	320.7	12.3	26.2
MB383	T230E/V231N/S238E/S239D	106.4	5.4	19.6
MB384	T230E/V231N/P232A/S238E/S239D	125.1	6.3	19.8
MB385	T230E/V231N/P232N/S238E/S239D	151.7	7.9	19.2
MB386	T230E/V231N/P232W/S238E/S239D	268.0	14.5	18.6
MB387	T230E/V231N/P232Y/S238E/S239D	318.7	16.7	19.1
MB388	T230E/V231P/S238E/S239D	277.3	10.8	25.9
MB389	T230E/V231P/P232A/S238E/S239D	244.8	7.0	35.3
MB390	T230E/V231P/P232N/S238E/S239D	521.7	11.9	44.0
MB391	T230E/V231P/P232W/S238E/S239D	281.2	10.9	25.9
MB392	T230E/V231P/P232Y/S238E/S239D	257.2	14.5	17.8
MB393	T230E/V231T/S238E/S239D	89.9	5.6	16.0
M8394	T230E/V231T/P232A/S238E/S239D	133.8	7.5	17.8
MB395	T230E/V231T/P232N/S238E/S239D	153.7	8.2	18.7
MB396	T230E/V231T/P232W/S238E/S239D	297.2	17.9	16.6
MB397	T230E/V231T/P232Y/S238E/S239D	554.8	19.3	28.9
MB398	T230E/V231W/S238E/S239D	45.8	3.5	13.0
MB399	T230E/V231W/P232A/S238E/S239D	71.8	3.9	18.2
MB400	T230E/V231W/P232N/S238E/S239D	81.7	5.5	15.0
MB401	T230E/V231W/P232W/S238E/S239D	162.3	6.9	23.7
MB402	T230E/V231W/P232Y/S238E/S239D	207.5	12.0	17.4
M8404	T230D/V231A/P232Y/S238E/S239D	235.7	8.6	27.6
MB405	T230I/V231A/P232Y/S238E/S239D	145.5	8.0	18.2
MB406	T230P/V231A/P232Y/S238E/S239D	191.1	6.5	29.6
MB407	T230Q/V231A/P232Y/S238E/S239D	164.4	9.8	16.9
MB408	V231A/P232Y/S238E/S239D	163.2	13.1	12.5
MB409	T230D/P232Y/S238E/S239D	192.5	10.7	18.0
MB410	T230I/P232Y/3238E/S239D	104.0	6.7	15.5
MB411	T230P/P232Y/S238E/S239D	132.2	8.1	16.4
MB412	T230Q/P232Y/S238E/S239D	113.3	8.3	13.7
MB413	P232Y/S238E/S239D	107.9	11.9	9.1
MB414	T230D/V231D/P232Y/S238E/S239D	189.4	8.1	23.6
MB415	T230I/V231D/P232Y/S238E/S239D	159.2	9.1	17.5
MB416	T230P/V231D/P232Y/S238E/S239D	189.0	6.3	30.2
MB417	T230Q/V231D/P232Y/S238E/S239D	189.5	10.7	17.8
MB418	V231D/P232Y/S238E/S239D	261.9	20.0	13.1
MB419	T230D/V231N/P232Y/S238E/S239D	215.6	11.6	18.6
MB420	T230I/V231N/P232Y/S238E/S239D	123.8	7.1	17.5
MB421	T230P/V231N/P232Y/S238E/S239D	178.3	9.0	19.9
MB422	T230Q/V231N/P232Y/S238E/S239D	144.2	8.9	16.3
MB423	V231N/P232Y/S238E/S239D	143.1	9.2	15.5
MB424	T230D/V231P/P232A/S238E/S239D	104.2	5.1	20.4
MB425	T230I/V231P/P232A/S238E/S239D	194.3	5.5	35.2
MB426	T230PA/231P/P232A/S238E/S2390	111.8	4.4	25.2
MB427	T230Q/V231P/P232A/S238E/S239D	217.4	7.0	31.1
MB428	V231P/P232A/S238E/S239D	214.9	8.8	24.4
MB429	T230D/V231P/P232N/S238E/S239D	136.8	6.8	20.3
MB430	T230I/V231P/P232N/S238E/S239D	206.7	6.3	33.0
MB431	T230P/V231P/P232N/S238E/S239D	112.8	4.2	26.8
MB432	T230Q/V231P/P232N/S238E/S239D	342.8	10.7	32.2
MB433	V231P/P232N/S238E/S239D	302.7	11.6	26.2
MB434	T230D/V231T/P232Y/S238E/S239D	256.8	15.5	16.7
MB435	T230I/V231T/P232Y/S238E/S239D	146.5	8.7	16.8
MB436	T230P/V231T/P232Y/S238E/S239D	150.8	8.4	18.0
MB437	T230Q/V231T/P232Y/S238E/S239D	197.6	11.5	17.3
MB438	V231T/P232Y/S238E/S239D	282.9	15.7	18.0
(Relative binding activity: value determined by dividing the KD value of H237-mIgG1/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR, Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-mIgG1/MRAL-k0)

[0348] From these results (FIGS. 4 and 5 and Table 5), many variants were found to enhance binding activity against mFcγRII while maintaining or improving I/A (mFcγRII selectivity), compared with those of H237-MB337/MRAL-k0, one of the best variants found in Example 3 before the combination study. The effects of such combined alterations of the amino acids at EU numbering positions 230, 231, and 232 were effects unpredictable from the comprehensive analysis results of the H237-mIgG1/MRAL-k0-templated point-mutation variants obtained in Example 2. In other words, the combinations of the alterations found this time were combinations of the alterations that were able to be found for the first time by this study. The results of Table 5 showed that all of the variants evaluated in this study were superior in relative I/A (mFcγRII selectivity) to the antibodies having the conventional Fc variants shown in Table 1 of Example 1 while some of the variants were also much superior in relative mFcγRII-binding activity to the antibodies having the conventional Fc variants. Among them, H237-MB390/MRAL-k0 with 5 alterations (T230E/V231P/P232N/S238E/S239D) introduced in H237-mIgG1/MRAL-k0, and H237-MB397/MRAL-k0 with 5 alterations (T230E/V231T/P232Y/S238E/S239D) introduced in H237-mIgG1/MRAL-k0 exhibited values as high as 44.0-fold and 28.9-fold relative I/A (mFcγRII selectivity), respectively, with the value of H237-mIgG1/MRAL-k0 as 1, while being both effective for strongly enhancing relative mFcγRII-binding activity by more than 500 times compared with that of H237-mIgG1/MRAL-k0, demonstrating that these Fc variants are much superior in both selectivity and binding activity to the conventional Fc variants. These results implied that use of these Fc variants with selectively enhanced mFcγRII binding enables Fc variants with selectively enhanced hFcγRIIb binding to be more accurately evaluated for their drug efficacy and safety in humans in in vivo and in vitro tests using mice.

[0349] For reference, Table 6 shows the KD values for each mFcγR and I/A (mFcγRII selectivity) of H237-mIgG1/MRAL-k0 and each variant that exhibited 200-fold or more relative mFcγRII-binding activity with the value of H237-mIgG1/MRAL-k0 as 1. “Name” in the table represents the name of the H chain constant region of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Table 6 were alterations introduced to the H chain constant region (SEQ ID NO: 4) of mouse IgG1 (mIgG1).

[0350]

TABLE 6
				I/A
Name		KD	KD	(mFcγRII
(CH)	Introduced alteration	(mFcγRII)	(mFcγRIII)	selectivity)
mIgG1	—	2.10E−07	2.82E−07	1.3
MB340	T230E/V231A/P232W/S238E/S239D	9.52E−10	2.86E−08	30.0
MB341	T230E/V231D/P232W/S238E/S239D	7.82E−10	2.46E−08	31.4
MB373	T230E/V231A/P232Y/S238E/S239D	5.38E−10	1.82E−08	33.8
MB379	T230E/P232Y/S238E/S239D	7.68E−10	2.32E−08	30.2
MB382	T230E/V231D/P232Y/S238E/S239D	6.55E−10	2.30E−08	35.1
MB386	T230E/V231N/P232W/S238E/S239D	7.84E−10	1.95E−08	24.9
MB387	T230E/V231N/P232Y/S238E/S239D	6.59E−10	1.69E−08	25.6
MB388	T230E/V231P/S238E/S239D	7.57E−10	2.62E−08	34.6
MB389	T230E/V231P/P232A/S238E/S239D	8.58E−10	4.06E−08	47.3
MB390	T230E/V231P/P232N/S238E/S239D	4.03E−10	2.37E−08	59.0
MB391	T230E/V231P/P232W/S238E/S239D	7.47E−10	2.59E−08	34.7
MB392	T230E/V231P/P232Y/S238E/S239D	8.17E−10	1.95E−08	23.9
MB396	T230E/V231T/P232W/S238E/S239D	7.07E−10	1.58E−08	22.3
MB397	T230E/V231T/P232Y/S238E/S239D	3.79E−10	1.46E−08	38.7
MB402	T230E/V231W/P232Y/S238E/S239D	1.01E−09	2.36E−08	23.3
MB404	T230D/V231A/P232Y/S238E/S239D	8.91E−10	3.30E−08	37.0
MB418	V231D/P232Y1S238E/S239D	8.02E−10	1.41E−08	17.6
MB419	T230D/V231N/P232Y/S238E/S239D	9.74E−10	2.43E−08	25.0
MB427	T230Q/V231P/P232A/S238E/S239D	9.66E−10	4.03E−08	41.7
MB428	V231P/P232A/S238E/S239D	9.77E−10	3.20E−08	32.7
MB430	T230I/V231P/P232N/S238E/S239D	1.02E−09	4.50E−08	44.3
MB432	T230Q/V231P/P232N/S238E/S239D	6.13E−10	2.64E−08	43.1
MB433	V231P/P232N/S238E/S239D	6.94E−10	2.44E−08	35.2
MB434	T230D/V231T/P232Y/S238E/S239D	8.18E−10	1.83E−08	22.3
MB438	V231T/P232Y/S238E/S239D	7.42E−10	1.79E−08	24.1
(I/A (mFcγRII selectivity): value determined by dividing the KD value for mFcγRIII by the KD value for mFcyRII)

[0351] In Example 4, the optimum combination of alterations of the amino acids at EU numbering positions 230, 231, and 232 was studied to successfully prepare variants excellent in enhanced mFcγRII binding and I/A (mFcγRII selectivity). In this Example 5, amino acid substitution at EU numbering position 239 was studied for the purpose of further improving I/A (mFcγRII selectivity) and preventing enhancement in binding to mFcγRIII. In the foregoing, the amino acid Ser at EU numbering position 239 was substituted by Asp. In this study, the amino acid at EU numbering position 239 was newly substituted by Glu, Met, or Trp and substituted by the original amino acid Ser. The antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab. For the study, 9 variants shown in Table 7 were selected from among the variants obtained in Example 4, and given template names. In this context, variants having the same sequences except for the amino acid at EU numbering position 239 were commonly given the same template name. These 9 variants were altered as templates to substitute the amino acid at EU numbering position 239 by Glu, Met, Trp, or Ser. The resulting variants were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200. The group of these variants also including the templated variants was designated as S239X variants.

[0352]

TABLE 7
		Template
Variant name	Introduced alteration	name
H237-MB373/MRAL-k0	T230E/N231A/P232Y/S238E/S239D	T1
H237-MB382/MRAL-k0	T230E/N231D/P232Y/S238E/S239D	T2
H237-MB387/MRAL-k0	T230E/N231N/P232Y/S238E/S239D	T3
H237-MB397/MRAL-k0	T230E/N231T/P232Y/S238E/S239D	T4
H237-MB379/MRAL-k0	T230E/P232Y/S238E/S239D	T5
H237-MB389/MRAL-k0	T230E/N231P/P232A/S238E/S239D	T6
H237-MB425/MRAL-k0	T230I/V231P/P232A/S238E/S239D	T7
H237-MB390/MRAL-k0	T230E/N231P/P232N/S238E/S239D	T8
H237-MB432/MRAL-k0	T230Q/N231P/P232N/S238E/S239D	T9

[0353] The results of analyzing interaction with each mFcγR were plotted according to the following method: the KD value of unmutated H237-mIgG1/MRAL-k0 for mFcγR was divided by the KD value of each S239X variant for mFcγR, and the obtained value was used as an index for the relative binding activity for each mFcγR. The horizontal axis indicates I/A (mFcγRII selectivity) which is a value determined by dividing the KD value of each S239X variant for mFcγRIII by its KD value for mFcγRII, and the vertical axis indicates the value of the relative binding activity of each S239X variant for mFcγRII (FIG. 6). In this drawing, the variant having Asp (D) as the amino acid at EU numbering position 239 was indicated by filled circle; the variant having Glu (E) as the amino acid at EU numbering position 239 was indicated by filled square; the variant having Met (M) as the amino acid at EU numbering position 239 was indicated by filled rhombus; the variant having Ser (S) as the amino acid at EU numbering position 239 was indicated by filled triangle; and the variant having Trp (W) as the amino acid at EU numbering position 239 was indicated by filled inverted triangle. In order to compare the effects of the types of the amino acid at EU numbering position 239 on each template, FIG. 7 was drawn by the method given below. The lower row of the horizontal axis represents the type of the amino acid at EU numbering position 239, and the upper row of the horizontal axis represents the template name. The vertical axis indicates the relative mFcγRII-binding activity (filled square) and relative I/A (mFcγRII selectivity) (open square) of each S239X variant with the values of H237-mIgG1/MRAL-k0 as 1.

[0354] Table 8 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the S239X variants evaluated in this study with the values of H237-mIgG1/MRAL-k0 as 1. “Name” in the table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Table 8 were alterations introduced to the H chain constant region (SEQ ID NO: 4) of mouse IgG1 (mIgG1).

[0355]

TABLE 8
				Relative	Relative
		Amino acid		mFcγRII-	mFcγRIII-	Relative I/A
		at EU	Tem-	binding	binding	(mFcγRII
Name		numbering	plate	activity	activity	selectivity)
(CH)	Introduced alteration	position 239	name	(mIgG1 = 1)	(mIgG1 = 1)	(mIgG1 = 1)
rnIgG1	—	S		1.0	1.0	1.0
MB373	T230E/V231A/P232Y/S238E/S239D	D	T1	390.4	15.5	25.2
MB382	T230E/V231D/P232Y/S238E/S239D		T2	320.7	12.3	26.2
MB387	T230E/V231N/P232Y/S238E/S239D		T3	318.7	16.7	19.1
MB397	T230E/V231T/P232Y/S238E/S239D		T4	554.8	19.3	28.9
MB379	T230E/P232Y/S238E/S239D		T5	273.4	12.2	22.5
MB389	T230E/V231P/P232A/S238E/S239D		T6	244.8	7.0	35.3
MB425	T230I/V231P/P232A/S238E/S239D		T7	194.3	5.5	35.2
MB390	T230E/V231P/P232N/S238E/S239D		T8	521.7	11.9	44.0
MB432	T230Q/V231P/P232N/S238E/S239D		T9	342.8	10.7	32.2
MB468	T230E/V231A/P232Y/S238E/S239E	E	T1	63.1	2.8	22.2
MB469	T230E/V231D/P232Y/S238E/S239E		T2	57.1	2.8	20.3
MB470	T230E/V231N/P232Y/S238E/S239E		T3	63.8	4.9	13.1
MB471	T230E/V231T/P232Y/S238E/S239E		T4	91.4	4.8	18.9
MB472	T230E/P232Y/S238E/S239E		T5	39.4	2.5	15.9
MB473	T230E/V231P/P232A/S238E/S239E		T6	57.6	1.4	40.1
MB474	T230I/V231P/P232A/S238E/S239E		T7	42.9	1.1	37.6
MB475	T230E/V231P/P232N/S238E/S239E		T8	214.4	3.5	62.0
MB476	T230Q/V231P/P232N/S238E/S239E		T9	245.8	3.4	73.4
MB508	T230E/V231A/P232Y/S238E/S239M	M	T1	5.5	0.4	14.5
MB509	T230E/V231D/P232Y/S238E/S239M		T2	10.7	0.6	18.0
MB510	T230E/V231N/P232Y/S238E/S239M		T3	6.5	0.6	11.1
MB511	T230E/V231T/P232Y/S238E/S239M		T4	8.3	0.6	15.0
MB512	T230E/P232Y/S238E/S239M		T5	3.5	0.3	12.7
MB513	T230E/V231P/P232A/S238E/S239M		T6	46.3	0.6	83.8
MB514	T230I/V231P/P232A/S238E/S239M		T7	4.5	0.2	22.3
MB515	T230E/V231P/P232N/S238E/S239M		T8	165.0	1.7	100.0
MB516	T230Q/V231P/P232N/S238E/S239M		T9	38.6	1.6	24.3
MB481	T230E/V231A/P232Y/S238E	S	T1	8.5	0.6	14.1
MB482	T230E/V231D/P232Y/S238E		T2	14.1	0.7	21.1
MB483	T230E/V231N/P232Y/S238E		T3	9.4	0.9	10.8
MB484	T230E/V231T/P232Y/S238E		T4	14.9	1.1	14.1
MB485	T230E/P232Y/S238E		T5	5.0	0.5	10.2
MB486	T230E/V231P/P232A/S238E		T6	28.1	1.1	25.8
MB487	T230I/V231P/P232A/S238E		T7	6.8	0.5	13.5
MB488	T230E/V231P/P232N/S238E		T8	28.7	1.8	15.6
MB489	T230Q/V231P/P232N/S238E		T9	6.9	1.1	6.3
MB517	T230E/V231A/P232Y/S238E/S239W	W	T1	1.2	0.4	3.0
MB518	T230E/V231D/P232Y/S238E/S239W		T2	1.2	0.4	2.8
MB519	T230E/V231N/P232Y/S238EIS239W		T3	1.0	0.9	1.2
MB520	T230E/V231T/P232Y1S238E/S239W		T4	1.8	1.3	1.4
MB521	T230E/P232Y/S238E/S239W		T5	1.6	0.7	2.1
MB522	T230E/V231P/P232A/S238E/S239W		T6	1.5	0.1	10.3
MB523	T230I/V231P/P232A/S238E/S239W		T7	0.5	0.1	4.6
MB524	T230E/V231P/P232N/S238EIS239W		T8	10.0	0.3	29.8
MB525	T230Q/V231P/P232N/S238E/S239W		T9	2.8	0.3	10.3
(Relative binding activity: value determined by dividing the KD value of H237-mIgGl/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR,
Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-mIgGl/MRAL-k0)

[0356] As seen from the results of FIG. 7, the substitution of the amino acid at EU numbering position 239 by the same amino acid produced the common rank of mFcγRII-binding activity among the templates, though the degree of this change largely differed among the templates. In addition, no common behavior was observed in change in selectivity. These S239X variants had S238E alteration in common and additionally had alterations at some of EU numbering positions 230, 231, 232, and 239. These results demonstrated that the effects of amino acid substitution at EU numbering position 239 are influenced by the types of the amino acids at EU numbering positions 230, 231, and 232.

[0357] From the results of FIGS. 6 and 7 and Table 8, some variants with the amino acid at EU numbering position 239 substituted by Glu, Met, Ser, or Trp were newly found to reduce mFcγRII-binding activity compared with that of the variants containing the S239D alteration obtained in Example 4, but to maintain or improve relative I/A (mFcγRII selectivity). These variants also include an variant with mFcγRIII-binding activity enhanced by less than 2 times, suggesting that use of these Fc variants enables the effects of enhanced mFcγRII-binding activity to be more accurately evaluated while substantially excluding the influence of enhanced binding activity against mFcγRIII. Four variants, i.e., H237-MB475/MRAL-k0 (T230E, V231P, P232N, S238E, and S239E alterations were introduced in H237-mIgG1/MRAL-k0), H237-MB476/MRAL-k0 (T230Q, V231P, P232N, S238E, and S239E alterations were introduced in H237-mIgG1/MRAL-k0), H237-MB513/MRAL-k0 (T230E, V231P, P232A, S238E, and S239M alterations were introduced in H237-mIgG1/MRAL-k0), and H237-MB515/MRAL-k0 (T230E, V231P, P232N, S238E, and S239M alterations were introduced in H237-mIgG1/MRAL-k0) exhibited 62.1-fold, 73.4-fold, 83.9-fold, and 100-fold relative I/A (mFcγRII selectivity), respectively, with the value of H237-mIgG1/MRAL-k0 as 1 and were much superior to H237-MB390/MRAL-k0 having the highest selectivity (44-fold) in the foregoing.

[0358] For reference, Table 9 shows the KD values for each mFcγR and I/A (mFcγRII selectivity) of H237-mIgG1/MRAL-k0 and each variant that exhibited 200-fold or more relative mFcγRII-binding activity or 25-fold or more relative I/A (mFcγRII selectivity) compared with that of H237-mIgG1/MRAL-k0. “Name” in the table represents the name of the H chain constant region of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Table 9 were alterations introduced to the H chain constant region (SEQ ID NO: 4) of mouse IgG1 (mIgG1).

[0359]

TABLE 9
				I/A
Name		KD	KD	(mFcγRII
(CH)	Introduced alteration	(mFcgR2)	(mFcgR3)	selectivity)
mIgG1	—	2.10E−07	2.82E−07	1.3
MB373	T230E/V231A/P232Y/S238E/S239D	5.38E−10	1.82E−08	33.8
MB379	T230E/P232Y/S238E/S239D	7.68E−10	2.32E−08	30.2
MB382	T230E/V231D/P232Y/S238E/S239D	6.55E−10	2.30E−08	35.1
MB387	T230EN231N/P232Y/S238E/S239D	6.59E−10	1.69E−08	25.6
MB389	T230E/V231P/P232A/S238E/S239D	8.58E−10	4.06E−08	47.3
MB390	T230E/V231P/P232N/S238E/S239D	4.03E−10	2.37E−08	59.0
MB397	T230E/V231T/P232Y/S238E/S239D	3.79E−10	1.46E−08	38.7
MB425	T230I/V231P/P232A/S238E/S239D	1.08E−09	5.10E−08	47.2
MB432	T230Q/V231P/P232N/S238E/S239D	6.13E−10	2.64E−08	43.1
MB473	T230E/V231P/P232A/S238E/S239E	3.65E−09	1.96E−07	53.8
MB474	T230I/V231P/P232A/S238E/S239E	4.89E−09	2.47E−07	50.4
MB475	T230EN231P/P232N/S238E/S239E	9.79E−10	8.14E−08	83.1
MB476	T230Q/V231P/P232N/S238E/S239E	8.54E−10	8.40E−08	98.3
MB486	T230E/V231P/P232A/S238E	7.47E−09	2.58E−07	34.5
MB513	T230E/V231P/P232A/S238E/S239M	4.53E−09	5.09E−07	112.4
MB515	T230E/V231P/P232N/S238E/S239M	1.27E−09	1.71E−07	133.9
MB524	T230E/V231P/P232N/S238E/S239W	2.10E−08	8.37E−07	39.9
(I/A (mFcγRII selectivity): value determined by dividing the KD value for mFcγRII) by the KD value for mFcγRII)

[0360] In the foregoing, amino acid substitution at EU numbering positions 230, 231, 232, 238, and 239 was studied. Amino acid substitution at sites other than these positions was studied for the purpose of further enhancing mFcγRII-binding activity.

[0361] The antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab. H237-MB397/MRAL-k0 and H237-MB390/MRAL-k0 that exhibited relative mFcγRII-binding activity enhanced by 500 times or more compared with that of H237-mIgG1/MRAL-k0 in Example 4 were used as templates to introduce new alterations. The resulting variant groups were designated as MB397 variants and MB390 variants, respectively. These variants were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200.

[0362] The results of analyzing interaction with each mFcγR were plotted according to the following method: the KD value of templated H237-MB397/MRAL-k0 or H237-MB390/MRAL-k0 for mFcγR was divided by the KD value of each corresponding variant for mFcγR, and the obtained value was used as an index for the relative binding activity for each mFcγR with the value of H237-MB397/MRAL-k0 or H237-MB390/MRAL-k0 as 1. The horizontal axis indicates the value of the relative binding activity of each variant for mFcγRIII, and the vertical axis indicates the value of the relative binding activity of each variant for mFcγRII (FIG. 8: MB397 variants, FIG. 9: MB390 variants).

[0363] Table 10 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the evaluated MB397 variants with the values of H237-mIgG1/MRAL-k0 or H237-MB397/MRAL-k0 as 1. Likewise, Table 11 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the evaluated MB390 variants with the values of H237-mIgG1/MRAL-k0 or H237-MB390/MRAL-k0 as 1. “Name” in each table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Table 10 were alterations introduced to the H chain constant region (SEQ ID NO: 5) of MB397. All of the alterations described in Table 11 were alterations introduced to the H chain constant region (SEQ ID NO: 6) of MB390.

[0364]

TABLE 10
		Relative	Relative		Relative	Relative
		mFcγRII-	mFcγRIII-	Relative I/A	mFcγRII	mFcγRIII-	Relative I/A
	Alteration	binding	binding	(mFcγRII	binding	binding	(mFcγRII
Name	added to	activity	activity	selectivity)	activity	activity	selectivity)
(CH)	MB397	(MB397 = 1)	(MB397 = 1)	(MB397 = 1)	(mIgG1= 1)	(mIgG1= 1)	(mIgG1 = 1)
MB397	—	1.00	1.00	1.00	554.8	19.3	28.9
MB439	S267E	0.07	0.23	0.30	39.5	4.5	8.8
M B440	P271L	0.22	0.36	0.61	120.1	6.9	17.5
MB441	A330K	0.07	0.21	0.34	39.7	4.1	9.7
MB442	K334R	1.60	1.39	1.14	884.2	26.9	33.0
MB443	F296E	0.44	0.79	0.55	243.3	15.3	15.9
MB444	F296N	0.42	0.67	0.62	231.1	12.9	17.9
MB445	F296T	0.40	0.68	0.58	220.3	13.2	16.7
MB446	S298L	2.45	3.30	0.74	1360.1	63.7	21.4
MB447	S298M	1.10	1.63	0.67	608.0	31.4	19.4
MB448	N324D	0.95	1.30	0.73	525.1	25.1	20.9
MB449	N324L	0.28	0.56	0.50	154.3	10.7	14.4
MB450	N324M	0.68	1.18	0.58	376.6	22.7	16.6
MB451	A330G	0.11	0.50	0.22	60.1	9.7	6.2
MB452	A330Q	0.08	0.23	0.37	46.9	4.4	10.8
MB453	P331D	0.21	0.49	0.43	117.8	9.5	12.4
MB454	P331F	0.53	1.04	0.51	295.0	20.0	14.8
MB455	P331Y	0.60	1.38	0.43	331.7	26.6	12.5
MB456	E333N	0.12	0.23	0.53	67.9	4.5	15.2
MB457	E333Y	0.36	0.70	0.52	202.1	13.6	14.9
MB458	E333V	0.46	0.81	0.56	252.6	15.7	16.2
MB459	T335N	0.51	1.06	0.48	285.0	20.5	13.9
MB460	T335Y	0.60	1.10	0.54	331.6	21.2	15.7
MB461	S337I	0.45	0.97	0.46	246.9	18.8	13.2
MB462	S337K	0.39	0.78	0.49	213.9	15.1	14.2
MB463	S337W	0.55	1.12	0.49	307.2	21.6	14.3
MB464	S267A	0.16	0.39	0.40	88.5	7.6	11.7
MB465	Q295L	0.35	0.77	0.45	192.3	15.0	12.9
MB466	A326D	0.81	1.66	0.49	449.1	32.0	14.1
MB467	A327G	0.49	0.99	0.49	270.8	19.2	14.2
(Relative binding activity: value determined by dividing the KD value of H237-mIgGl/MRAL-k0 or H237-MB397/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR,
Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-mIgGl/MRAL-k0 or H237-MB397/MRAL-k0)

[0365]

TABLE 11
		Relative	Relative	Relative	Relative	Relative	Relative
		mFcγRII-	mFcγRIII-	I/A	mFcγRII-	mFcγRIII-	I/A
		binding	binding	(mFcγRII	binding	binding	(mFcγRII
		activity	activity	selectivity)	activity	activity	selectivity)
Name	Alteration added to	(MB390 =	(MB390 =	(MB390 =	(mIgG1 =	(mIgG1 =	(mIgG1 =
(CH)	MB390	1)	1)	1)	1)	1)	1)
MB390		1.00	1.00	1.00	521.7	11.9	44.0
MB477	S267A	0.38	0.25	1.49	195.7	3.0	65.3
MB478	Q295L	0.49	0.39	1.23	254.2	4.7	54.3
MB479	A326D	1.41	1.16	1.21	733.8	13.8	53.2
MB480	K334R	0.98	0.85	1.15	511.3	10.2	50.4
MB490	S298L	2.16	2.90	0.74	1127.8	34.6	32.7
MB491	S298M	0.92	1.05	0.87	478.0	12.4	38.5
MB492	N324D	1.19	0.92	1.29	621.5	10.9	57.0
MB493	S298L/N324D	2.73	3.77	0.72	1423.7	44.9	31.8
MB494	S298L/K334R	4.05	4.99	0.81	2111.4	59.4	35.6
MB495	S298M/N324D	1.20	1.45	0.82	623.1	17.2	36.3
MB496	S298M/K334R	1.70	1.71	0.99	883.5	20.3	43.6
MB497	N324D/K334R	1.48	1.32	1.12	772.6	15.7	49.3
MB498	S298L/N324D/K334R	6.40	7.15	0.89	3335.5	85.1	39.3
MB499	S298M/N324D/K334R	1.90	2.03	0.93	992.0	24.2	41.1
(Relative binding activity: value determined by dividing the KD value of H237-mIgGl/MRAL-k0 or H237-MB390/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR,
Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-mIgGl/MRAL-k0 or H237-MB390/MRAL-k0)

[0366] From these results (FIGS. 8 and 9 and Tables 10 and 11), it was newly found that: the introduction of one or two or more of the S298L, S298M, N324D, A326D, and K334R alterations enhances binding activity against mFcγRII without largely reducing I/A (mFcγRII selectivity); and these alterations are effective for enhancing binding activity against mFcγRII. The introduction of these alterations to the highly selective variants (H237-MB475/MRAL-k0, H237-MB476/MRAL-k0, H237-MB513/MRAL-k0, and H237-MB515/MRAL-k0) found in Example 5 is expected to further enhance binding activity against mFcγRII while maintaining their high selectivity.

(7-1) Evaluation of Time-Dependent Change in Plasma Concentration of Mouse Antibody with Selectively Enhanced Binding Activity Against mFcγRII

[0367] In the foregoing Examples, the antibodies having the Fc variants with selectively enhanced binding activity against mFcγRII were obtained. These antibodies having the Fc variants with selectively enhanced binding activity against mFcγRII were tested for time-dependent change in their in vivo plasma concentrations by comparison with antibodies having Fc variants with both mFcγRII-binding activity and mFcγRIII-binding activity enhanced at the same levels. For this purpose, the following tests were conducted using normal mice.

(7-2) Preparation of Antibody with Enhanced Binding Activity Against FcγR

[0368] The antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab. An anti-human IL-6 receptor antibody H237-mIgG1/MRAL-k0 comprised of H237-mIgG1 (SEQ ID NO: 7) having the H chain constant region mIgG1, and MRAL-k0, an anti-human IL-6 receptor antibody H237-MB367/MRAL-k0 comprised of H237-MB367 (SEQ ID NO: 8) having the Fc variant with selectively enhanced binding activity against mFcγRII, and MRAL-k0, and an anti-human IL-6 receptor antibody H237-mF46/MRAL-k0 comprised of H237-mF46 (SEQ ID NO: 9) having an Fc variant with mIgG1 Ser 239 (EU numbering) substituted by Asp and Ala 327 (EU numbering) substituted by Asp for the purpose of enhancing binding activity against mFcγRII and mFcγRIII, and MRAL-k0 were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200. Table 12 shows the binding activity against each mFcγR and I/A (mFcγRII selectivity) of each evaluated antibody. Furthermore, Table 13 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of each evaluated antibody with the values of H237-mIgG1/MRAL-k0 as 1. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Tables 12 and 13 were alterations introduced to the H chain constant region of H237-mIgG1 (SEQ ID NO: 7).

[0369]

TABLE 12
				I/A
	Introduced	KD	KD	(mFcγRII
Antibody name	alteration	(mFcγRII)	(mFcγRIII)	selectivity)
H237-	—	2.10E−07	2.82E−07	1.3
mIgG1/MRAL-
k0
H237-	T230E/N231A/	1.32E−09	4.54E−08	34.3
MB367/MRAL-	P232N/S238E/
k0	S239D
H237-	S239D/A327D	1.33E−09	6.40E−09	4.8
mF46/MRAL-k0
(I/A (mFcγRII selectivity): value determined by dividing the KD value of each variant for mFcγRIII by its KD value for mFcγRII)

[0370]

TABLE 13
		Relative	Relative	Relative
		mFcγRII-	mFcγRIII-	I/A
		binding	binding	(mFcγRII
	Introduced	activity	activity	selectivity)
Antibody name	alteration	(mIgG1 = 1)	(mIgG1 = 1)	(mIgG1 = 1)
H237-	—	1.0	1.0	1.0
mIgG1/MRAL-k0
H237-	T230E/V231A/P23	158.6	6.2	25.6
MB367/MRAL-k0	2N/S238E/S239D
H237-mF46/MRAL-	S239D/A327D	158.5	44.0	3.6
k0
(Relative binding activity: value determined by dividing the KD value of H237-mIgG1/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR, Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-mIgG1/MRAL-k0)

[0371] From these results, H237-MB367/MRAL-k0 was confirmed to have an Fc variant with more selectively enhanced mFcγRII binding which enhanced binding activity against mFcγRII at the same level as that of H237-mF46/MRAL-k0 and prevented enhancement in binding to mFcγRIII.

(7-3) In Vivo Test Using Normal Mice

[0372] A soluble human IL-6 receptor (prepared in Reference Example 3) was administered alone or simultaneously with an anti-human IL-6 receptor mouse antibody to each normal mouse (C57BL/6J mouse, Charles River Laboratories Japan, Inc.). Then, the anti-human IL-6 receptor mouse antibody was evaluated for its disposition. The soluble human IL-6 receptor solution (5 μg/mL) or the mixed solution of the soluble human IL-6 receptor and the anti-human IL-6 receptor mouse antibody was administered to the tail vein at a dose of 10 mL/kg. The doses of the antibody and the soluble human IL-6 receptor were set to 1 mg/kg and 50 μg/kg, respectively. The anti-human IL-6 receptor mouse antibody used was H237-MB367/L104-mk1 and H237-mF46/L104-mk1 derived from the aforementioned H237-MB367/MRAL-k0 and H237-mF46/MRAL-k0, respectively, by the replacement of its L chain with L104-mk1 (SEQ ID NO: 32) comprised of the variable region L104 of the L chain VL3-CK of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825 and the constant region mk1 of the mouse chain. After a lapse of 5 minutes, 7 hours, 1 day, 2 days, 3 days, 7 days, 14 days, and 21 days after the administration of the anti-human IL-6 receptor mouse antibody, blood was collected from the mouse. The collected blood was immediately centrifuged at 15,000 rpm at 4° C. for 15 minutes to obtain plasma. The separated plasma was stored in a refrigerator set to −20° C. or lower until measurement.

(7-4) Measurement of Anti-Human IL-6 Receptor Mouse Antibody Concentration in Plasma by ELISA

[0373] The anti-human IL-6 receptor mouse antibody concentration in the mouse plasma was measured by ELISA. First, a soluble human IL-6 receptor was dispensed to wells of Nunc-Immuno Plate, MaxiSoup (Nalge Nunc International). The plate was left standing overnight at 4° C. to prepare a soluble human IL-6 receptor-immobilized plate. Calibration curve samples containing the anti-human IL-6 receptor mouse antibody at a plasma concentration of 2.50, 1.25, 0.625, 0.313, 0.156, 0.078, or 0.039 μg/mL, and mouse plasma assay samples diluted 100-fold or more were prepared. These calibration curve samples and plasma assay samples were dispensed at a volume of 100 μL/well to the soluble human IL-6 receptor-immobilized plate, followed by stirring at room temperature for 2 hours. Then, the plate was reacted with Anti-Mouse IgG-Peroxidase antibody (Sigma-Aldrich Corp.) at room temperature for 2 hours. The chromogenic reaction of the reaction solution in each well was performed using TMB One Component HRP Microwell Substrate (BioFX Laboratories, Inc.) as a substrate. The reaction was stopped by the addition of 1 N sulfuric acid (Showa Chemical Industry Co., Ltd.). The absorbance of the reaction solution in each well was measured at 450 nm using a microplate reader. The antibody concentration in the mouse plasma was calculated using analysis software SOFTmax PRO (Molecular Devices, LLC) from the absorbance of the calibration curve. The results are shown in FIG. 10.

[0374] As seen from the results of FIG. 10, H237-MB367/L104-mk1 with selectively enhanced binding activity against mFcγRII exhibited time-dependent change that kept its plasma concentration high compared with that of H237-mF46/L104-mk1 with enhanced binding activity against both mFcγRII and mFcγRIII. This suggests that the antibody H237-mF46/L104-mk1 in comparison with H237-MB367/L104-mk1 disappears via mFcγRIII due to its enhanced binding not only to mFcγRII but to mFcγRIII. In other words, use of such a low selective molecule seems to fail to accurately test the effects of a molecule with selectively enhanced binding activity against mouse FcγRII (or human FcγRIIb). These results demonstrated that use of an Fc variant, such as MB367, which has selectively enhanced binding activity against mFcγRII enables the effects of selectively enhanced binding activity against mouse FcγRII (or human FcγRIIb) to be more accurately tested in vivo.

[0375] For the purpose of obtaining Fc having enhanced binding activity against mFcγRII and also having high selectivity, two highly selective variants (H237-MB476/MRAL-k0 and H237-MB515/MRAL-k0) found in Example 5 were studied to introduce one or two or more of the S298L, N324D, A326D, and K334R alterations found in Example 6.

[0376] The antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab. H237-MB476/MRAL-k0 and H237-MB515/MRAL-k0 were used as templates to introduce new alterations. These variants were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200.

[0377] The results of analyzing interaction with each mFcγR were plotted according to the following method: the KD value of templated H237-MB476/MRAL-k0 or H237-MB515/MRAL-k0 for mFcγR was divided by the KD value of each corresponding variant for mFcγR, and the obtained value was used as an index for the relative binding activity for each mFcγR with the value of H237-MB476/MRAL-k0 or H237-MB515/MRAL-k0 as 1. Also, I/A (mFcγRII selectivity) which is a value determined by dividing the KD value of each variant for mFcγRIII by its KD value for mFcγRII was divided by I/A (mFcγRII selectivity) of H237-MB476/MRAL-k0 or H237-MB515/MRAL-k0, and the obtained value was used as an index for the relative I/A (mFcγRII selectivity) with the value of H237-MB476/MRAL-k0 or H237-MB515/MRAL-k0 as 1. The horizontal axis indicates the value of the relative I/A (mFcγRII selectivity) of each variant, and the vertical axis indicates the value of the relative binding activity of each variant for mFcγRII (FIG. 13). Likewise, the horizontal axis indicates the value of the relative I/A (mFcγRII selectivity) of each variant, and the vertical axis indicates the value of the relative binding activity of each variant for mFcγRII, with the values of unmutated H237-mIgG1/MRAL-k0 as 1 (FIG. 14).

[0378] Table 14 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the variants evaluated in this study with the values of H237-mIgG1/MRAL-k0 or each template (H237-MB476/MRAL-k0 or H237-MB515/MRAL-k0) as 1. “Name” in the table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. The alterations described in Table 14 were alterations introduced to the H chain constant region (SEQ ID NO: 37) of the template MB476 or the H chain constant region (SEQ ID NO: 38) of the template MB515.

[0379]

TABLE 14
			Relative	Relative	Relative	Relative	Relative	Relative
			mFcγRII-	mFcγRIII-	I/A	mFcγRII-	mFcγRIII-	I/A
			binding	binding	(mFcγRII	binding	binding	(mFcγRII
			activity	activity	selectivity)	activity	activity	selectivity)
Name		Alteration added to	(template =	(template =	(template =	(mIgG1 =	(mIgG1 =	(mIgG1 =
(CH)	template	template	1)	1)	1)	1)	1)	1)
MB476	MB476	—	1.00	1.00	1.00	261.2	2.6	99.0
MB526		S298L	0.89	3.23	0.28	232.4	8.5	27.3
MG527		S298L/N324D	1.05	2.09	0.50	273.3	5.5	49.5
MB528		S298L/A326D	1.44	5.52	0.26	375.3.	14.6	25.7
MB529		S298L/K334R	1.08	2.24	0.48	281.9	5.9	47.7
MB530		N324D/A326D	2.38	3.04	0.78	622.6	8.0	77.6
MB531		N324D/K334R	0.88	1.25	0.70	228.8	3.3	69.1
MB532		A326D/K334R	1.26	2.35	0.54	328.6	6.2	53.0
MB533		S298L/N324D/A326D	1.51	2.74	0.55	393.6	7.2	54.5
MB534		S298L/N324D/K334R	1.61	12.79	0.13	420.7	33.8	12.5
MB535		S298L/A326D/K334R	1.61	3.21	0.50	421.7	8.5	49.8
MB536		N324D/A326D/K334R	1.52	2.90	0.52	396.0	7.7	51.7
M6537		S298L/N324D/A326D/K334R	1.95	3.36	0.58	510.1	8.9	57.4
MB515	MB515	—	1.00	1.00	1.00	137.3	1.3	104.4
MB538		S298L	0.63	1.30	0.48	86.2	1.7	50.3
MB539		S298L/N324D	0.77	1.45	0.53	105.1	1.9	55.0
MB540		S298L/A326D	1.09	2.15	0.51	149.4	2.8	52.7
MB541		S298L/K334R	0.75	2.48	0.30	103.0	3.3	31.6
MB542		N324D/A326D	2.80	2.57	1.09	384.2	3.4	113.7
MB543		N324D/K334R	1.42	1.69	0.84	195.3	2.2	87.7
MB544		A326D/K334R	2.01	2.45	0.82	276.2	3.2	85.6
MB545		S298L/N324D/A326D	1.19	2.02	0.59	163.4	2.7	61.6
MB546		S298L/N324D/K334R	1.15	4.28	0.27	158.1	5.6	28.1
MB547		S298L/A326D/K334R	1.24	3.43	0.36	170.3	4.5	37.7
MB548		N324D/A326 1K334R	2.60	2.99	0.87	356.7	3.9	90.9
MB549		S298L/N324D/A326D/K334R	1.53	4.11	0.37	210.0	5.4	38.9
(Relative binding activity: value determined by dividing the KD value of H237-mIgG1/MRAL-k0, H237-MB476/MRAL-k0, or H237-MB515/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR,
Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-mIgG1/MRAL-k0, H237-MB476/M RAL-k0, or H237-MB515/MRAL-k0)

[0380] From these results (FIGS. 13 and 14 and Table 14), some variants in which one or two or more of the S298L, N324D, A326D, and K334R alterations were introduced were found to enhance binding activity against mFcγRII without largely reducing I/A (mFcγRII selectivity). Of them, H237-MB530/MRAL-k0 (N324D/A326D alterations were introduced in H237-MB476/MRAL-k0), H237-MB542/MRAL-k0 (N324D/A326D alterations were introduced in H237-MB515/MRAL-k0), H237-MB548/MRAL-k0 (N324D/A326D/K334R alterations were introduced in H237-MB515/MRAL-k0), H237-MB544/MRAL-k0 (A326D/K334R alterations were introduced in H237-MB515/MRAL-k0), and H237-MB543/MRAL-k0 (N324D/K334R alterations were introduced in H237-MB515/MRAL-k0) had relative mFcγRII-binding activity enhanced by 1.4 times or more, while maintaining 0.75-fold or more relative I/A (mFcγRII selectivity), with the values of each template as 1.

[0381] Particularly, H237-MB530/MRAL-k0, H237-MB542/MRAL-k0, and H237-MB548/MRAL-k0 exhibited 350-fold or more relative mFcγRII-binding activity and 70-fold or more relative I/A (mFcγRII selectivity) with the values of H237-mIgG1/MRAL-k0 as 1 and were much superior in I/A (mFcγRII selectivity) to the above-prepared variants having the same level of mFcγRII binding activity thereas.

(8-2) Study on Amino Acid Substitution at EU Numbering Position 239

[0382] As shown in Example 5, some variants with the amino acid substitution at EU numbering position 239 were found to maintain or improve I/A (mFcγRII selectivity). Thus, the substitution of this position by other amino acids that had not been studied in Example 5 was also studied.

[0383] The antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab. The same 9 variants (all having Asp as the amino acid at EU numbering position 239) as those used in Example 5 were altered as templates to substitute the amino acid at EU numbering position 239 by Leu, Asn, Tyr, or Phe. Of the 9 templated variants, two templated variants H237-MB389/MRAL-k0 and H237-MB390/MRAL-k0 were also altered to substitute the amino acid at EU numbering position 239 by Ala, Gly, Val, Ile, Pro, Thr, Gln, Arg, or His. Of the 9 templated variants, the templated variant H237-MB432/MRAL-k0 was also altered to substitute the amino acid at EU numbering position 239 by Val or Ile. These variants were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200.

[0384] The results of analyzing interaction with each mFcγR were plotted according to the following method: in order to compare the effects of the types of the amino acid at EU numbering position 239 on each template, the KD value of each templated variant for mFcγR was divided by the KD value of each variant prepared from the templated variant for mFcγR, and the obtained value was used as an index for the relative binding activity for each mFcγR with the value of each templated variant as 1. Also, I/A (mFcγRII selectivity) which is a value determined by dividing the KD value of each variant for mFcγRIII by its KD value for mFcγRII was divided by I/A (mFcγRII selectivity) of its templated variant, and the obtained value was used as an index for the relative I/A (mFcγRII selectivity) with the value of each templated variant as 1. The horizontal axis indicates the type of the amino acid at EU numbering position 239, and the vertical axis indicates relative mFcγRII-binding activity (filled square) and relative I/A (mFcγRII selectivity) (open square) on a template basis (FIG. 15).

[0385] Table 15 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the variants evaluated in this study with the values of H237-mIgG1/MRAL-k0 as 1. “Name” in the table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Table 15 were alterations introduced to the H chain constant region (SEQ ID NO: 4) of mouse IgG1 (mIgG1).

[0386]

TABLE 15
			Amino acid	Relative	Relative
			at EU	mFcγRII-	mFcγRIII-	Relative I/A
			numbering	binding	binding	(mFcγRII
Name			position	activity	activity	selectivity)
(CH )	Alteration introduced to mIgG1	template	239	(mIgG1 = 1)	(mIgG1 = 1)	(mIgG1 = 1)
MB623	T230E/V231A/P232Y/S238E/S239L	MB373	L	0.53	0.09	5.99
MB624	T230E/V231D/P232Y/S238E/S239L	MB382	L	0.80	0.10	8.14
MB625	T230E/V231N/P232Y/S238E/S239L	MB387	L	0.67	0.12	5.53
MB626	T230E/V231T/P232Y/S238E/S239L	MB397	L	0.81	0.12	6.78
MB627	T230E/P232Y/S238E/S239L	MB379	L	0.32	0.09	3.45
MB628	T230E/V231P/P232A/S238E/S239L	MB389	L	2.20	0.06	35.18
MB629	T230I/V231P/P232A/S238E/S239L	MB425	L	0.38	0.04	9.08
MB630	T230E/V231P/P232N/S238E/S239L	MB390	L	14.31	0.25	57.03
MB631	T230Q/V231P/P232N/S238E/S239L	MB432	L	4.29	0.28	15.32
MB632	T230E/V231A/P232Y/S238E/S239N	MB373	N	3.64	0.18	19.97
MB633	T230E/V231D/P232Y/S238E/S239N	MB382	N	2.77	0.17	16.12
MB634	T230E/V231N/P232Y/S238E/S239N	MB387	N	2.52	0.21	12.20
MB635	T230E/V231T/P232Y/S238E/S239N	MB397	N	5.06	0.29	17.54
MB636	T230E/P232Y/S238E/S239N	MB379	N	4.41	0.14	30.84
MB637	T230E/V231P/P232A/S238E/S239N	MB389	N	2.60	0.15	17.48
MB638	T230I/V231P/P232A/S238E/S239N	MB425	N	0.75	0.08	9.02
MB639	T230E/V231P/P232N/S238E/S239N	MB390	N	4.91	0.38	12.98
MB640	T230Q/V231P/P232N/S238E/S239N	MB432	N	1.06	0.18	5.87
MB641	T230E/V231A/P232Y/S238E/S239Y	MB373	Y	1.47	0.13	10.98
MB642	T230E/V231D/P232Y/S238E/S239Y	MB382	Y	1.87	0.08	22.12
MB643	T230E/V231N/P232Y/S238E/S239Y	MB387	Y	1.66	0.14	11.82
MB644	T230E/V231T/P232Y/S238E/S239Y	MB397	Y	4.55	0.30	15.32
MB645	T230E/P232Y/S238E/S239Y	MB379	Y	1.17	0.20	5.87
MB646	T230E/V231P/P232A/S238E/S239Y	MB389	Y	4.38	0.15	29.58
MB647	T230I/V231P/P232A/S238E/S239Y	MB425	Y	1.05	0.10	10.48
MB648	T230E/V231P/P232N/S238E/S239Y	MB390	Y	10.75	0.64	16.77
MB649	T230Q/V231P/P232N/S238E/S239Y	MB432	Y	3.89	0.51	7.63
MB650	T230E/V231A/P232Y/S238E/S239F	MB373	F	0.24	0.05	4.51
MB651	T230E/V231D/P232Y/S238E/S239F	MB382	F	0.30	0.04	6.85
MB652	T230E/V231N/P232Y/S238E/S239F	MB387	F	0.28	0.06	4.60
MB653	T230E/V231T/P232Y/S238E/S239F	MB397	F	0.41	0.10	3.95
MB654	T230E/P232Y/S238E/S239F	MB379	F	0.27	0.07	3.73
MB655	T230E/V231P/P232A/S238E/S239F	MB389	F	0.40	0.06	6.99
MB656	T230I/V231P/P232A/S238E/S239F	MB425	F	N.B.	0.02	—
MB657	T230E/V231P/P232N/S238E/S239F	MB390	F	1.77	0.08	21.92
MB658	T230Q/V231P/P232N/S238E/S239F	MB432	F	0.51	0.06	8.77
MB704	T230E/V231P/P232A/S238E/S239A	MB389	A	14.09	0.87	16.16
MB705	T230E/V231P/P232A/S238E/S239G	MB389	G	8.71	0.75	11.71
MB706	T230E/V231P/P232A/S238E/S239V	MB389	V	0.23	N.B.	—
MB707	T230E/V231P/P232A/S238E/S239I	MB389	I	0.37	N.B.	—
MB708	T230E/V231P/P232A/S238E/S239P	MB389	P	0.28	0.03	8.24
MB709	T230E/V231P/P232A/S238E/S239T	MB389	T	0.61	0.04	16.61
MB710	T230E/V231P/P232A/S238E/S239Q	MB389	Q	50.80	1.22	41.88
MB711	T230E/V231P/P232A/S238E/S239R	MB389	R	0.05	N.B.	—
MB712	T230E/V231P/P232A/S238E/S239H	MB389	H	0.16	N.B.	—
MB713	T230E/V231P/P232N/S238E/S239A	MB390	A	23.48	2.50	9.41
MB714	T230E/V231P/P232N/S238E/S239G	MB390	G	14.16	1.61	8.81
MB715	T230E/V231P/P232N/S238E/S239V	MB390	V	0.89	0.02	37.80
MB716	T230E/V231P/P232N/S238E/S239I	MB390	I	3.98	0.05	86.85
MB717	T230E/V231P/P232N/S238E/S239P	MB390	P	0.41	0.03	12.51
MB718	T230E/V231P/P232N/S238E/S239T	MB390	T	0.85	0.05	16.80
MB719	T230E/V231P/P232N/S238E/S239Q	MB390	Q	70.38	2.31	30.54
MB720	T230E/V231P/P232N/S238E/S239R	MB390	R	0.08	N.B.	—
MB721	T230E/V231P/P232N/S238E/S239H	MB390	H	0.30	N.B.	—
MB792	T230Q/V231P/P232N/S238E/S239V	MB432	V	0.31	N.B.	—
MB793	T230Q/V231P/P232N/S238E/S239I	MB432	I	1.17	0.05	22.87
(N.B.: although assay was conducted, binding was not observable because of being too weak, Relative binding activity: value determined by dividing the KD value of H237-mIgG1/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR, Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-mIgG1/MRAL-k0)

[0387] As seen from the results of FIG. 15 and Table 15, mFcγRII-binding activity was largely reduced in all of the variants, whereas I/A (mFcγRII selectivity) was maintained or improved in some of the variants. In FIG. 15, variants having 0.8-fold or more relative I/A (mFcγRII selectivity) with the value of each templated variant as 1 were indicated by arrow with the name of CH. Of the variants with improved I/A (mFcγRII selectivity), H237-MB716/MRAL-k0, H237-MB630/MRAL-k0, and H237-MB710/MRAL-k0 had mFcγRII selectivity as high as 40-fold or more relative I/A (mFcγRII selectivity) with the value of H237-mIgG1/MRAL-k0 as 1. The introduction of, for example, the additional alterations shown in Example 6 or 8-1 to these variants as templates is expected to be able to prepare variants with further enhanced binding activity against mFcγRII while maintaining high mFcγRII selectivity.

(8-3) Study on Additional Alteration to H237-MB630/MRAL-k0

[0388] The study of Example 8-2 newly obtained variants having high mFcγRII selectivity. Of them, one variant (H237-MB630/MRAL-k0) was examined for further amino acid substitution for the purpose of enhancing mFcγRII-binding activity.

[0389] The antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab. H237-MB630/MRAL-k0 found in Example 8-2 was used as a template to introduce the alterations studied in Example 6, etc. These variants were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200.

[0390] For the results of analyzing interaction with each mFcγR, the KD value of H237-MB630/MRAL-k0 or H237-mIgG1/MRAL-k0 for mFcγR was divided by the KD value of each variant for mFcγR, and the obtained value was used as an index for the relative binding activity for each mFcγR with the value of H237-MB630/MRAL-k0 or H237-mIgG1/MRAL-k0 as 1. Also, I/A (mFcγRII selectivity) which is a value determined by dividing the KD value of each variant for mFcγRIII by its KD value for mFcγRII was divided by I/A (mFcγRII selectivity) of H237-MB716/MRAL-k0 or H237-mIgG1/MRAL-k0, and the obtained value was used as an index for the relative I/A (mFcγRII selectivity) with the value of H237-MB716/MRAL-k0 or H237-mIgG1/MRAL-k0 as 1. The horizontal axis indicates the value of the relative binding activity of each variant against mFcγRIII with the value of H237-MB630/MRAL-k0 as 1, and the vertical axis indicates the value of the relative binding activity of each variant against mFcγRII with the value of H237-MB630/MRAL-k0 as 1 (FIG. 16).

[0391] Table 16 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the variants evaluated in this study with the values of H237-MB630/MRAL-k0 or H237-mIgG1/MRAL-k0 as 1. “Name” in the table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Table 16 were alterations introduced to the H chain constant region (SEQ ID NO: 39) of MB630.

[0392]

TABLE 16
		Relative	Relative		Relative	Relative
		mFcγRII-	mFcγRIII-	Relative I/A	mFcγRII-	mFcγRIII-	Relative I/A
		binding	binding	(mFcγRII	binding	binding	(mFcγRII
Name		activity	activity	selectivity)	activity	activity	selectivity)
(CH)	Alteration added to MB630	(MB630 = 1)	(MB630 = 1)	(MB630 = 1)	(mIgG1 = 1)	(mIgG1 = 1)	(mIgG1 = 1)
MB748	S267A	0.70	0.70	1.00	11.7	0.14	85.8
MB749	Q295L	1.52	1.96	0.78	25.3	0.38	66.5
MB750	A326D	1.77	2.06	0.86	29.4	0.40	73.8
MB751	K334R	1.53	1.63	0.94	25.4	0.32	80.5
MB752	S298L	0.36	0.44	0.81	6.0	0.09	69.7
MB753	S298M	0.34	0.34	1.01	5.7	0.07	86.4
MB754	N324D	1.26	1.28	0.99	21.0	0.25	84.5
MB755	S298L/N324D	0.45	0.58	0.78	7.6	0.11	67.1
MB756	S298L/K334R	0.64	1.09	0.59	10.6	0.21	50.3
MB757	S298M/N324D	0.46	0.45	1.01	7.6	0.09	86.8
MB758	S298M/K334R	0.59	0.69	0.86	9.8	0.13	73.4
MB759	N324D/K334R	2.03	2.25	0.91	33.8	0.44	77.6
MB760	S298L/N324D/K334R	0.85	1.42	0.60	14.1	0.28	51.2
MB761	S298M/N324D/K334R	0.81	0.92	0.87	13.4	0.18	74.9
MB762	F296E	0.40	0.51	0.79	4.4	0.09	49.9
MB763	F296N	0.31	0.41	0.76	3.4	0.07	47.9
MB764	F296T	0.23	0.32	0.71	2.5	0.05	45.3
MB765	N324L	0.49	0.64	0.76	5.3	0.11	48.3
MB766	N324M	1.29	1.55	0.83	14.0	0.27	52.8
MB767	A330G	0.16	0.19	0.88	1.8	0.03	55.9
MB768	A330Q	0.50	0.81	0.61	5.4	0.14	38.9
MB769	P331D	0.31	0.38	0.82	3.3	0.06	51.7
MB770	P331F	1.23	1.40	0.88	13.3	0.24	55.5
MB771	P331Y	1.27	1.53	0.83	13.8	0.26	52.7
MB772	E333N	0.32	0.42	0.76	3.5	0.07	47.9
MB773	E333Y	1.17	1.25	0.93	12.7	0.22	59.2
MB774	E333V	0.87	1.05	0.83	9.4	0.18	52.4
MB775	T335N	0.84	1.02	0.82	9.1	0.18	52.0
MB776	T335Y	1.04	1.15	0.90	11.3	0.20	57.1
MB777	S337I	0.74	0.72	1.02	9.7	0.17	58.2
MB778	S337K	0.57	0.65	0.88	6.1	0.11	55.4
MB779	S337W	0.92	1.02	0.91	10.0	0.18	57.3
MB780	A327G	1.86	2.29	0.81	20.2	0.39	51.4
MB781	A330K	0.48	0.77	0.62	5.2	0.13	39.1
MB782	Q295L/N324D	1.96	2.89	0.68	21.3	0.50	42.9
MB783	Q295L/A326D	2.82	4.34	0.65	30.6	0.75	41.2
MB784	Q295L/K334R	1.36	2.24	0.61	14.7	0.38	38.4
MB785	N324D/A326D	2.29	2.85	0.81	24.9	0.49	51.1
MB786	A326D/K334R	2.50	3.33	0.75	27.2	0.57	47.6
MB787	Q295L/N324D/A326D	3.55	5.57	0.64	38.5	0.96	40.3
MB788	Q295L/N324D/K334R	2.06	3.46	0.60	22.4	0.59	37.8
MB789	Q295L/A326D/K334R	2.84	4.79	0.59	30.9	0.82	37.6
MB790	N324D/A326D/K334R	3.08	4.09	0.75	33.5	0.70	47.8
MB791	Q295L/N324D/A326D/K334R	3.70	6.43	0.58	40.1	1.10	36.4
MB807	Q295L/N324M	1.67	2.11	0.79	21.9	0.49	45.1
MB808	Q295L/A327G	2.22	3.40	0.65	29.2	0.78	37.3
MB809	Q295L/P331F	1.44	1.92	0.75	19.0	0.44	43.0
MB810	Q295L/P331Y	1.58	2.24	0.71	20.8	0.52	40.3
MB811	Q295L/E333Y	1.69	1.87	0.90	22.2	0.43	51.6
MB812	N324D/A327G	2.54	2.93	0.87	33.4	0.68	49.6
MB813	N324D/P331F	1.24	1.29	0.96	16.3	0.30	55.0
MB814	N324D/P331Y	1.37	1.48	0.93	18.0	0.34	52.9
MB815	N324D/E333Y	1.34	1.30	1.02	17.6	0.30	58.5
MB816	N324M/A326D	2.31	2.84	0.82	30.4	0.65	46.6
MB817	N324M/A327G	2.17	2.27	0.95	28.5	0.52	54.6
MB818	N324M/P331F	1.19	1.25	0.95	15.6	0.29	54.3
MB819	N324M/P331Y	1.38	1.40	0.98	18.1	0.32	56.1
MB820	N324M/E333Y	1.49	1.43	1.04	19.5	0.33	59.3
MB821	N324M/K334R	1.86	1.96	0.95	24.4	0.45	54.3
MB822	A326D/A327G	3.33	4.02	0.83	43.8	0.93	47.4
MB823	A326D/P331F	1.90	2.13	0.90	25.0	0.49	51.2
MB824	A326D/P331Y	2.13	2.45	0.87	28.0	0.56	49.6
MB825	A326D/E333Y	2.16	2.17	1.00	28.4	0.50	57.0
MB826	A327G/P331F	1.41	1.48	0.95	18.5	0.34	54.5
MB827	A327G/P331Y	1.63	1.64	0.99	21.5	0.38	56.8
MB828	A327G/E333Y	2.16	2.14	1.01	28.4	0.49	57.6
MB829	A327G/K334R	2.57	2.75	0.93	33.8	0.63	53.4
MB830	P331F/E333Y	0.37	0.36	1.01	4.8	0.08	57.7
MB831	P331F/K334R	1.70	1.71	0.99	22.3	0.39	56.8
MB832	P331Y/E333Y	0.40	0.40	0,99	5.2	0.09	56.3
MB833	P331Y/K334R	1.92	1.94	0.99	25.3	0.45	56.5
MB834	E333Y/K334R	1.29	1.25	1.03	17.0	0.29	58.9
MB835	K268D	2.00	3.05	0.66	26.3	0.70	37.4
MB846	K268D/A326D/A327G	6.80	11.57	0.59	72.1	2.12	34.1
MB847	Q295L/A326D/A327G	4.12	7.24	0.57	43.7	1.33	33.0
MB848	N324D/A326D/A327G	4.33	5.00	0.86	45.8	0.92	50.1
MB849	A326D/A327G/P331Y	2.97	3.54	0.84	31.4	0.65	48.6
MB850	A326D/A327G/E333Y	4.12	4.30	0.96	43.7	0.79	55.5
MB851	A326D/A327G/K334R	4.13	5.23	0.79	43.8	0.96	45.9
MB852	Q295L/N324D/A326D/A327G	5.76	10.02	0.58	61.0	1.83	33.4
MB853	Q295L/A326D/A327G/P331Y	3.31	6.20	0.53	35.0	1.13	31.0
MB854	Q295L/A326D/A327G/E333Y	4.77	6.84	0.70	50.6	1.25	40.5
MB855	Q295L/A326D/A327G/K334R	3.41	6.21	0.55	36.2	1.14	31.9
MB856	N324D/A326D/A327G/P331Y	4.23	4.95	0.85	44.8	0.91	49.5
MB857	N324D/A326D/A327G/E333Y	4.21	4.92	0.85	44.6	0.90	49.6
MB858	N324D/A326D/A327G/K334R	5.86	6.92	0.85	62.0	1.27	49.1
MB859	A326D/A327G/P331Y/K334R	3.22	3.90	0.83	34.2	0.71	48.0
MB860	A326D/A327G/E333Y/K334R	3.74	4.07	0.92	39.6	0.75	53.3
MB861	K268D/N324D/A326D/A327G	7.25	13.18	0.55	76.8	2.41	31.9
MB862	K268D/A326D/A327G/P331Y	6.41	10.83	0.59	67.9	1.98	34.4
MB863	K268D/A326D/A327G/E333Y	7.68	12.71	0.60	81.3	2.33	35.0
MB864	K268D/A326D/A327G/K334R	10.42	19.86	0.52	110.4	3.63	30.4
MB865	K268D/Q295L/A326D/A327G	7.91	18.26	0.43	83.8	3.34	25.1
(Relative binding activity: value determined by dividing the KD value of H237-MB630/MRAL-k0 or H237-mIgG1/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR, Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-MB630/MRAL-k0 or H237-mIgG1/MRAL-k0)

[0393] From the results of FIG. 16 and Table 16, many specimens with amino acid substitution newly introduced in H237-MB630/MRAL-k0 were found to reduce mFcγRII selectivity, but to enhance mFcγRII-binding activity. In addition, some variants were found to enhance or reduce mFcγRII-binding activity while maintaining high mFcγRII selectivity.

(8-4) Study on Additional Alteration to H237-MB716/MRAL-k0

[0394] Additional amino acid substitution was also studied on H237-MB716/MRAL-k0 (having Ile as the amino acid at EU numbering position 239) shown in the study of Example 8-2 to have higher mFcγRII selectivity than that of H237-MB630/MRAL-k0 (having Leu as the amino acid at EU numbering position 239). 7 alterations (K268D, Q295L, N324D, A326D, A327G, E333Y, and K334R) were selected from among the alterations found to enhance mFcγRII-binding activity by introduction to H237-MB630/MRAL-k0 in Example 8-3. These alterations were introduced in various combinations and studied.

[0395] The antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab. H237-MB716/MRAL-k0 was used as a template to introduce the alterations. These variants were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200.

[0396] For the results of analyzing interaction with each mFcγR, the KD value of H237-MB716/MRAL-k0 or H237-mIgG1/MRAL-k0 for mFcγR was divided by the KD value of each variant for mFcγR, and the obtained value was used as an index for the relative binding activity for each mFcγR with the value of H237-MB716/MRAL-k0 or H237-mIgG1/MRAL-k0 as 1. Also, I/A (mFcγRII selectivity) which is a value determined by dividing the KD value of each variant for mFcγRIII by its KD value for mFcγRII was divided by I/A (mFcγRII selectivity) of H237-MB716/MRAL-k0 or H237-mIgG1/MRAL-k0, and the obtained value was used as an index for the relative I/A (mFcγRII selectivity) with the value of H237-MB716/MRAL-k0 or H237-mIgG1/MRAL-k0 as 1. The horizontal axis indicates the value of the relative binding activity of each variant against mFcγRIII with the value of H237-MB716/MRAL-k0 as 1, and the vertical axis indicates the value of the relative binding activity of each variant against mFcγRII with the value of H237-MB716/MRAL-k0 as 1 (FIG. 17).

[0397] Table 17 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the variants evaluated in this study with the values of H237-MB716/MRAL-k0 or H237-mIgG1/MRAL-k0 as 1. “Name” in the table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Table 17 were alterations introduced to the H chain constant region (SEQ ID NO: 47) of MB716.

[0398]

TABLE 17
		Relative	Relative	Relative	Relative	Relative	Relative
		mFcγRII-	mFcγRII)-	I/A	mFcγRII-	mFcγRII)-	I/A
		binding	binding	(mFcγRII	binding	binding	(mFcγRll
		activity	activity	selectivity)	activity	activity	selectivity)
Name	Alteration added to	(MB716 =	(MB716 =	(MB716 =	(mIgG1 =	(mIgG1 =	(mIgG1 =
(CH)	MB716	1)	1)	1)	1)	1)	1)
MB866	A326D/A327G	3.0	3.02	0.99	12.96	0.18	72.42
MB867	K268D/A326D/A327G	8.1	14.35	0.57	35.23	0.85	41.41
MB868	K268D/N324D/A326D/	8.4	14.45	0.58	36.63	0.86	42.76
	A327G
MB869	K268D/A326D/A327G/	9.4	15.85	0.60	41.01	0.94	43.65
	E333Y
MB870	K268D/A326D/A327G/	8.9	17.64	0.50	38.60	1.05	36.92
	K334R
MB871	K268D/Q295L/A326D/	14.2	28.17	0.51	61.82	1.67	37.02
	A327G
MB875	K268D/Q295L/N324D/	16.8	32.31	0.52	72.84	1.92	38.03
	A326D/A327G
MB876	K268D/Q295L/A326D/	13.5	24.85	0.54	58.66	1.48	39.81
	A327G/E333Y
MB877	K268D/N324D/A326D/	12.7	24.36	0.52	55.26	1.45	38.26
	A327G/K334R
(Relative binding activity: value determined by dividing the KD value of H237-MB716/MRAL-k0 or H237-mIgG1/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR, Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-MB716/MRAL-k0 or H237-mIgG1/MRAL-k0)

[0399] From the results of FIG. 17 and Table 17, as observed in Example 8-3, many specimens with amino acid substitution newly introduced in H237-MB716/MRAL-k0 were found to reduce mFcγRII selectivity, but to enhance mFcγRII-binding activity. In addition, some variants were found to enhance mFcγRII-binding activity while maintaining high mFcγRII selectivity.

[0400] As mentioned above, H237-MB716/MRAL-k0 had higher mFcγRII selectivity than that of H237-MB630/MRAL-k0. The H237-MB716/MRAL-k0-templated variants exhibited higher mFcγRII selectivity than that of the H237-MB630/MRAL-k0-templated variants. These results suggest that the introduction of various alterations to H237-MB716/MRAL-k0 as a template can yield many specimens having high mFcγRII selectivity.

[0401] As described herein, immune complexes are formed through the binding of antibodies to multivalent antigens and seem to induce various adverse reactions by their interaction with activating FcγR. This might reduce the values of the antibodies as drugs. For circumventing this problem while maintaining the effects mediated by FcγRIIb, it is desirable to maintain binding to FcγRIIb and, at the same time, to selectively reduce binding to activating FcγR. Nonetheless, there has been no report on an Fc variant that has such features in relation to mouse FcγR. Accordingly, in this Example, study was conducted for the purpose of preparing an Fc variant with reduced binding activity against activating mFcγRIII while keeping binding activity against inhibitory mFcγRII at the same level as that of naturally occurring mIgG1.

(9-1) Study on Combined Alterations to Reduce Binding Activity Against mFcγRIII

[0402] From the results of analyzing the interaction of the variants having 1 amino acid mutation obtained in Example 2 with mFcγRII and mFcγRIII, alterations to selectively reduce binding activity against mFcγRIII were searched for, and 10 variants were selected therefrom. These variants were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200.

[0403] For the results of analyzing interaction with each mFcγR, the KD value of H237-mIgG1/MRAL-k0 for mFcγR was divided by the KD value of each variant for mFcγR, and the obtained value was used as an index for the relative binding activity for each mFcγR with the value of H237-mIgG1/MRAL-k0 as 1. Also, I/A (mFcγRII selectivity) which is a value determined by dividing the KD value of each variant for mFcγRIII by its KD value for mFcγRII was divided by I/A (mFcγRII selectivity) of H237-mIgG1/MRAL-k0, and the obtained value was used as an index for the relative I/A (mFcγRII selectivity) with the value of H237-mIgG1/MRAL-k0 as 1.

[0404] Table 18 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the evaluated variants. “Name” in the table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Table 18 were alterations introduced to the H chain constant region (SEQ ID NO: 4) of mouse IgG1 (mIgG1).

[0405]

TABLE 18
		Relative	Relative	Relative
		mFcγRII-	mFcγRIII)-	I/A
	Alteration	binding	binding	(mFcγRII
Name	introduced to	activity	activity	selectivity)
(CH)	mIgG1	(mIgG1 = 1)	(mIgG1 = 1)	(mIgG1 = 1)
MB092	S238D	0.16	0.05	2.87
MB093	S238E	2.48	0.61	4.05
MB075	V237E	0.12	0.07	1.80
MB112	S239F	0.47	0.27	1.77
MB125	S239W	0.81	0.48	1.70
MB146	F241D	0.85	0.21	4.09
MB147	F241E	0.95	0.36	2.64
MB159	F241T	0.37	0.28	1.33
MB208	S267M	0.40	0.26	1.52
MB258	S298H	0.37	0.32	1.17
(Relative binding activity: value determined by dividing the KD value of H237-mIgG1/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR, Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRII) by the KD value for mFcγRII) of each variant by I/A of H237-mIgG1/MRAL-k0; the value of H237-mIgG1/MRAL-k0 used was a value obtained by the same assay run as that of each variant)

[0406] From the results of Table 18, all of the variants were confirmed to improve mFcγRII selectivity by reducing binding activity against mFcγRIII relative to mFcγRII. Thus, study was conducted on whether the combination of these alterations could yield a variant strongly effective for reducing binding activity against mFcγRIII to thereby improve mFcγRII selectivity.

[0407] The antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab. H237-mIgG1/MRAL-k0 was used as a template to introduce the alterations. These variants were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200.

[0408] For the results of analyzing interaction with each mFcγR, the KD value of H237-mIgG1/MRAL-k0 for mFcγR was divided by the KD value of each variant for mFcγR, and the obtained value was used as an index for the relative binding activity for each mFcγR with the value of H237-mIgG1/MRAL-k0 as 1. Also, I/A (mFcγRII selectivity) which is a value determined by dividing the KD value of each variant for mFcγRIII by its KD value for mFcγRII was divided by I/A (mFcγRII selectivity) of H237-mIgG1/MRAL-k0, and the obtained value was used as an index for the relative I/A (mFcγRII selectivity) with the value of H237-mIgG1/MRAL-k0 as 1.

[0409] Table 19 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the variants evaluated in this study with the values of H237-mIgG1/MRAL-k0 as 1. “Name” in the table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Table 19 were alterations introduced to the H chain constant region (SEQ ID NO: 4) of mouse IgG1 (mIgG1).

[0410]

TABLE 19
		Relative	Relative	Relative
		mFcγRII-	mFcγRIII-	I/A
		binding	binding	(mFcγRII
Name	Alteration	activity	activity	selectivity)
(CH)	introduced to mIgG1	(mIgG1 = 1)	(mIgG1 = 1)	(mIgG1 = 1)
MB561	V237E/S238E	0.48	0.07	7.08
MB562	S238E/S239F	0.05	0.02	1.99
MB563	S238E/S239W	0.20	0.08	2.54
MB564	S238E/F241D	0.32	0.11	3.02
MB565	S238E/F241E	0.66	0.23	2.88
MB566	S238E/F241T	0.18	0.10	1.80
MB567	S238E/S267M	0.21	0.07	2.82
MB568	S238E/S298H	0.71	0.18	3.83
MB571	V237E/S239F	0.22	0.05	4.34
MB572	V237E/S239W	0.26	0.07	3.66
MB573	V237E/F241D	0.43	0.06	6.81
MB574	V237E/F241E	0.27	0.10	2.83
MB575	V237E/F241T	0.08	0.05	1.67
MB576	S239F/F241D	1.54	0.60	2.55
MB577	S239F/F241E	2.51	1.19	2.10
MB578	S239F/F241T	0.39	0.25	1.55
MB579	S239W/F241D	0.89	0.34	2.60
MB580	S239W/F241E	1.38	0.61	2.26
MB581	S239W/F241T	0.69	0.42	1.65
MB584	V237E/S238D	0.08	0.02	3.92
MB585	S238D/S239F	0.06	0.03	1.84
MB586	S238D/S239W	0.13	0.08	1.68
MB587	S238D/F241D	1.33	0.60	2.22
MB588	S238D/F241E	2.01	1.01	1.99
MB589	S238D/F241T	0.23	0.19	1.24
MB590	S238D/S267M	N.B.	N.B.	—
MB591	S238D/S298H	0.08	0.02	4.61
MB594	T230E/V237E/S238E	1.85	0.10	18.70
MB595	T230E/S238E/S239F	0.09	0.05	1.64
MB596	T230E/S238E/S239W	0.55	0.17	3.25
MB597	T230E/S238E/F241D	1.28	0.54	2.38
MB598	T230E/S238E/S267M	0.41	0.08	5.31
MB599	T230E/V237E/S239F	0.70	0.11	6.58
MB600	T230E/V237E/S239W	1.24	0.25	4.95
MB601	T230E/V237E/F241D	0.55	0.10	5.55
MB602	T230E/V237E/S238D	0.26	0.05	4.80
MB603	T230E/S238D/S239F	0.12	0.06	1.96
MB604	T230E/S238D/S239W	0.34	0.16	2.13
MB605	T230E/S238D/F241D	9.85	4.40	2.24
MB606	T230E/S238D/S267M	0.05	N.B.	—
MB607	V237E/S238E/S239E	3.14	0.18	17.40
MB608	S238E/S239E/F241D	0.42	0.13	3.21
MB609	S238E/S239E/S267M	2.66	0.32	8.22
MB610	V237E/S239E/F241D	0.23	N.B.	—
MB611	V237E/S238D/S239E	1.11	0.09	11.90
MB612	S238D/S239E/F241D	0.81	0.30	2.72
MB613	S238D/S239E/S267M	0.24	0.06	3.77
MB614	V237E/S238E/S239D	10.90	0.84	12.94
MB615	S238E/S239D/F241D	0.59	0.14	4.16
MB616	S238E/S239D/S267M	4.06	0.57	7.15
MB617	V237E/S239D/F241D	0.84	0.15	5.51
MB619	S238D/S239D/F241D	0.62	0.16	3.91
MB620	S238D/S239D/S267M	0.23	0.07	3.19
MB621	S238D/S239E	3.15	0.23	13.70
MB622	S238D/S239D	3.83	0.40	9.48
MB618	V237E/S238D/S239D	1.63	0.13	12.23
(N.B.: although assay was conducted, binding was not observable because of being too weak, Relative binding activity: value determined by dividing the KD value of H237-mIgG1/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR, Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-mIgG1/MRAL-k0; the value of H237-mIgG1/MRAL-k0 used was a value obtained by the same assay run as that of each variant)

[0411] From the results of Table 19, a plurality of variants having the combination of the alterations were found to have more reduced binding activity against mFcγRIII and improved mFcγRII selectivity. In addition, some variants were also found to keep binding activity against mFcγRII at the same level as that of naturally occurring mIgG1. Six variants (MB594, MB599, MB601, MB611, MB617, and MB618) were successfully obtained which differed in mFcγRII-binding activity by within 2 times from H237-mIgG1/MRAL-k0 (0.5-fold or more and 2.0-fold or less relative mFcγRII-binding activity with the value of H237-mIgG1/MRAL-k0 as 1) and had 5-fold or more relative I/A (mFcγRII selectivity) compared with that of H237-mIgG1/MRAL-k0.

(9-2) Study on Introduction of mFcγR Binding-Reducing Alteration to Variant with Selectively Enhanced mFcγRII-Binding Activity

[0412] The variants with selectively enhanced binding to mFcγRII were altered as templates to reduce binding activity against all mFcγ receptors also including mFcγRII. The resulting variants were expected to keep binding activity against mFcγRII at the same level as that of mIgG1 while having reduced binding activity against mFcγRIII compared with that of mIgG1.

[0413] P232K and S239K were used as alterations to reduce binding activity against all mFcγ receptors. As in Example 5, 9 variants were used as templates and studied for the effects of the P232K and S239K alterations.

[0414] The antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab. The same 9 variants (all having Asp as the amino acid at EU numbering position 239) as those used in Example 5 were used as templates to introduce the alterations. These variants were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200.

[0415] For the results of analyzing interaction with each mFcγR, the KD value of H237-mIgG1/MRAL-k0 for mFcγR was divided by the KD value of each variant for mFcγR, and the obtained value was used as an index for the relative binding activity for each mFcγR with the value of H237-mIgG1/MRAL-k0 as 1. Also, I/A (mFcγRII selectivity) which is a value determined by dividing the KD value of each variant for mFcγRIII by its KD value for mFcγRII was divided by I/A (mFcγRII selectivity) of H237-mIgG1/MRAL-k0, and the obtained value was used as an index for the relative I/A (mFcγRII selectivity) with the value of H237-mIgG1/MRAL-k0 as 1.

[0416] Table 20 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the variants evaluated in this study with the values of H237-mIgG1/MRAL-k0 as 1. “Name” in the table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. The alterations described in Table 20 were alterations introduced to the H chain constant region (SEQ ID NO: 40) of the template MB373, the H chain constant region (SEQ ID NO: 41) of the template MB382, the H chain constant region (SEQ ID NO: 42) of the template MB387, the H chain constant region (SEQ ID NO: 5) of the template MB397, the H chain constant region (SEQ ID NO: 43) of the template MB379, the H chain constant region (SEQ ID NO: 44) of the template MB389, the H chain constant region (SEQ ID NO: 45) of the template MB425, the H chain constant region (SEQ ID NO: 6) of the template MB390, or the H chain constant region (SEQ ID NO: 46) of the template MB432.

[0417]

TABLE 20
			Relative	Relative	Relative
			mFcγRII-	mFcγRIII-	I/A
		Alteration	binding	binding	(mFcγRII
Name		added to	activity	activity	selectivity)
(CH)	template	template	(mIgG1 = 1)	(mIgG1 = 1)	(mIgG1 = 1)
MB669	MB373	S239K	N.B.	0.04	—
MB670	MB382		N.B.	0.06	—
MB671	MB387		N.B.	0.04	—
MB672	MB397		0.30	0.07	4.35
MB673	MB379		N.B.	0.04	—
MB674	MB389		N.B.	0.06	—
MB675	MB425		N.B.	0.01	—
MB676	MB390		0.22	0.12	1.84
MB677	MB432		N.B.	0.03	—
MB364	MB373	P232K	6.55	1.35	4.84
MB678	MB379		8.03	2.01	4.00
MB679	MB382		7.57	1.68	4.51
MB680	MB387		8.97	1.75	5.13
MB681	MB389		13.88	1.83	7.60
MB682	MB390		14.01	2.14	6.55
MB683	MB397		7.70	0.90	8.55
MB684	MB432		5.37	1.02	5.28
(N.B.: although assay was conducted, binding was not observable because of being too weak, Relative binding activity: value determined by dividing the KD value of H237-mIgG1/MRAL-k0 for each mFcγR by the KD value of each variant for each mFcγR, Relative I/A (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing the KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-mIgG1/MRAL-k0; the value of H237-mIgG1/MRAL-k0 used was a value obtained by the same assay run as that of each variant)

[0418] As seen from the results of Table 20, some variants having the introduced P232K alteration maintained 5-fold or more relative I/A (mFcγRII selectivity), while their relative mFcγRII-binding activity was enhanced by approximately 5 to 15 times. These results implied that it is effective to decrease the number of alterations for enhancing binding activity against mFcγRII or to further combine therewith alterations to reduce binding to mFcγRIII as studied in Example 9-1.

[0419] On the other hand, the introduction of the S239K alteration remarkably reduced binding activity against mFcγRII. Since the 9 variants used as templates had approximately 200-fold to 600-fold relative mFcγRII-binding activity, the variants with more enhanced binding activity against mFcγRII as with H237-MB498/MRAL-k0 and H237-MB494/MRAL-k0 (having approximately 3300-fold and approximately 2100-fold relative mFcγRII-binding activity, respectively) found in Example 6 may be used as templates to keep binding activity against mFcγRII at the same level as that of mIgG1.

[0420] All of these 9 variants had the S239D alteration, which made a great contribution to enhancement in mFcγRII-binding activity. Alteration at this site therefore reduces its own enhancement itself in mFcγRII-binding activity. Accordingly, it may also be effective to adopt an alteration to reduce FcγR-binding activity at a site different from an already altered site. Such an alteration is possibly, for example, N297A alteration for eliminating N-linked sugar chains added to Asn 297 (EU numbering). Reportedly, antibodies exhibit significantly reduced binding to FcγR as a result of eliminating N-linked sugar chains added to Asn 297 (EU numbering) in their Fc regions (The Journal of Biological Chemistry, 2000, 276, 6591-6604).

(9-3) Study on Decrease of the Number of Alterations in Variant with Selectively Enhanced mFcγRII-Binding Activity

[0421] Decrease of the number of introduced alterations from the variants with selectively enhanced binding to mFcγRII was expected to obtain variants with reduced binding activity against mFcγRIII compared with that of mIgG1 while keeping binding activity against mFcγRII at the same level as that of mIgG1.

[0422] Of the variants prepared in the foregoing Examples up to Example 9-1, 7 variants (H237-MB594/MRAL-k0, H237-MB628/MRAL-k0, H237-MB632/MRAL-k0, H237-MB636/MRAL-k0, H237-MB642/MRAL-k0, H237-MB646/MRAL-k0, and H237-MB657/MRAL-k0) were selected from among variants having 1-fold to 5-fold relative mFcγRII-binding activity and 15-fold or more relative I/A (mFcγRII selectivity) with the values of H237-mIgG1/MRAL-k0 as 1, and studied for decrease of the number of the alterations introduced therein.

[0423] The antibody H chain variable region used was the variable region H237 (SEQ ID NO: 1) of the H chain VH3-IgG1 of the anti-IL-6 receptor antibody Fv4-IgG1 described in WO2009/125825. The antibody L chain commonly used was the L chain MRAL-k0 (SEQ ID NO: 2) of the anti-IL-6 receptor antibody tocilizumab. The aforementioned 7 variants were used as templates to substitute the amino acids at the alteration sites by the amino acids before the alteration. These variants were expressed and purified by the method of Reference Example 1 and evaluated for their binding to mFcγRII and mFcγRIII by the method of Reference Example 2 using Biacore T200.

[0424] For the results of analyzing interaction with each mFcγR, the KD value of H237-mIgG1/MRAL-k0 for mFcγR was divided by the KD value of each variant for mFcγR, and the obtained value was used as an index for the relative binding activity for each mFcγR with the value of H237-mIgG1/MRAL-k0 as 1. Also, I/A (mFcγRII selectivity) which is a value determined by dividing the KD value of each variant for mFcγRIII by its KD value for mFcγRII was divided by I/A (mFcγRII selectivity) of H237-mIgG1/MRAL-k0, and the obtained value was used as an index for the relative I/A (mFcγRII selectivity) with the value of H237-mIgG1/MRAL-k0 as 1. The horizontal axis indicates the value of the relative binding activity of each variant (also including the 7 templated variants) against mFcγRIII, and the vertical axis indicates the value of relative binding activity of each variant (also including the 7 templated variants) against mFcγRII (FIG. 18).

[0425] Table 21 shows the relative binding activity against each mFcγR and relative I/A (mFcγRII selectivity) of all of the variants (also including the 7 templated variants) evaluated in this study with the values of H237-mIgG1/MRAL-k0 as 1. “Name” in the table represents the name of the H chain constant region (CH) of each evaluated variant. As for alterations, “X000Z” represents the substitution of amino acid X at EU numbering position 000 by amino acid Z. In this context, X and Z represent the one-letter codes of the amino acid residues. All of the alterations described in Table 21 were alterations introduced to the H chain constant region (SEQ ID NO: 4) of mouse IgG1 (mIgG1).

[0426]

TABLE 21
		Relative	Relative	Relative
		mFcγRII-	mFcγRIII-	I/A
		binding	binding	(mFcγRII
Name		activity	activity	selectivity)
(CH)	Introduced alteration	(mIgG1 = 1)	(mIgG1 = 1)	(mIgG1 = 1)
MB594	T230E/V237E/S238E	1.302	0.057	23.0
MB628	T230E/V231P/P232A/S23XE/S239L	2.087	0.083	25.0
MB632	T230E/V231A/P232Y/S238E/S239N	3.720	0.236	15.8
MB636	T230E/P232Y/S238E/S239N	3.917	0.172	22.8
MB642	T230E/V231D/P232Y/S238E/S239Y	1.647	0.100	16.5
MB646	T230E/V231P/P232A/S238E/S239Y	3.804	0.176	21.7
MB657	T230E/V231P/P232N/S238E/S239F	1.541	0.087	17.7
MB645	T230E/P232Y/S238E/S239Y	1.058	0.217	4.9
MB685	V231P/P232A/S238E/S239L	0.606	0.093	6.5
MB686	T230E/P232A/S238E/S239L	0.167	0.052	3.2
MB687	T230E/P231P/S238E/S239L	0.943	0.096	9.8
MB688	P232Y/S238E/S239N	0.634	0.081	7.8
MB689	T230E/S238E/S239N	0.413	0.075	5.5
MB690	V231P/P232A/S238E/S239Y	1.597	0.188	8.5
MB691	T230E/P232A/S238E/S239Y	0.582	0.071	8.2
MB692	T230E/V231P/S238E/S239Y	1.747	0.115	15.2
MB693	V231D/P232Y/S238E/S239Y	1.219	0.094	12.9
MB694	T230E/V231D/S238ES239Y	0.544	0.031	17.5
MB695	V231P/P232N/S238E/S239F	0.435	0.088	5.0
MB696	T230E/P232N/S238E/S239F	0.400	0.094	4.3
MB697	T230E/V231P/S238E/S239F	0.217	N.B.	—
MB698	T230E/V237E/S238E/S239L	0.194	0.024	8.1
MB699	T230E/V237ES238E/S239N	0.216	0.035	6.1
MB700	T230E/V237E/S238E/S239Y	0.559	0.044	12.7
MB701	T230E/V237E/S238E/S239F	0.187	N.B.	—
MB702	V231A/P232Y/S238E/S239N	0.960	0.145	6.6
MB703	T230E/V231A/S238E/S239N	0.943	0.104	9.1
(N.B.: although assay was conducted, binding was not observable because of being too weak, Relative binding activity: value determined by dividing the KD value of H237-mIgG1/MRAL-k0 mFcγR by the KD value of each variant for each mFcγR, Relative FA (mFcγRII selectivity): value determined by dividing I/A (value determined by dividing KD value for mFcγRIII by the KD value for mFcγRII) of each variant by I/A of H237-mIgG1/MRAL-k0; the value of H237-mIgG1/MRAL-k0 used was a value obtained by the same assay run as that variant)