Antigen-binding molecule capable of binding to plurality of antigen molecules repeatedly

Abstract

An objective of the present invention is to provide methods for promoting antigen uptake into cells by antigen-binding molecules, methods for increasing the number of times of antigen binding by one antigen-binding molecule, methods for promoting reduction of the antigen concentration in plasma by administering antigen-binding molecules, and methods for improving the plasma retention of an antigen-binding molecule, as well as antigen-binding molecules that allow enhanced antigen uptake into cells, antigen-binding molecules having an increased number of times of antigen binding, antigen-binding molecules that can promote reduction of the antigen concentration in plasma when administered, antigen-binding molecules with improved plasma retention, pharmaceutical compositions comprising the above antigen-binding molecules, and methods for producing them. The present inventors revealed that the above objective can be achieved by using antigen-binding molecules that show calcium-dependent antigen-antibody reaction.

1 - 74 . (canceled) 
     
     
         75 . An antibody comprising an antigen-binding domain and a human FcRn-binding domain, wherein the antibody has an antigen-binding activity that is lower under a low calcium concentration condition than under a high calcium concentration condition, wherein the low calcium concentration is an ionized calcium concentration of 0.1 μM to 30 μM and the high calcium concentration is an ionized calcium concentration of 100 μM to 10 mM and wherein the antigen-binding domain comprises a light chain variable domain and a heavy chain variable domain, each comprising three CDRs, and wherein a calcium-binding motif is located within a CDR of the light chain variable domain and/or within a CDR of the heavy chain variable domain. 
     
     
         76 . The antibody of  claim 75 , wherein the calcium-binding motif comprises the amino acid(s) at positions 30, 31, and/or 32 (Kabat numbering) in CDR1 of the light chain variable domain. 
     
     
         77 . The antibody of  claim 75 , wherein the calcium-binding motif comprises the amino acid at position 50 (Kabat numbering) in CDR2 of the light chain variable domain. 
     
     
         78 . The antibody of  claim 75 , wherein the calcium-binding motif comprises the amino acid at position 92 (Kabat numbering) in CDR3 of the light chain variable domain. 
     
     
         79 . The antibody of  claim 75 , wherein the calcium-binding motif comprises the amino acid(s) at positions 95, 96, 100a and/or 101 (Kabat numbering) in CDR3 of the heavy chain variable domain. 
     
     
         80 . The antibody of  claim 75 , wherein the antigen-binding activity of the antibody is lower at acidic pH than at neutral pH. 
     
     
         81 . The antibody of  claim 75 , wherein the FcRn-binding domain is a modified Fc region wherein the amino acid sequence of the modified Fc region varies from the sequence of a wild type Fc domain at one or more of positions 248, 250, 252, 254, 255, 256, 257, 258, 265, 286, 289, 297, 303, 305, 307, 308, 309, 311, 312, 314, 315, 317, 332, 334, 360, 376, 380, 382, 384, 385, 386, 387, 389, 424, 428, 433, 434, and 436 (EU numbering). 
     
     
         82 . A method of producing a calcium concentration-dependent antibody, the method comprising:
 (a) contacting an antigen with an antibody or a library of antibodies under a high calcium concentration condition, thereby producing an antigen/antibody complex, wherein the high calcium concentration is an ionized calcium concentration of 100 μM to 10 mM;   (b) placing the antigen/antibody complex under a low calcium concentration condition, wherein the low calcium concentration is an ionized calcium concentration of 0.1 μM to 30 μM;   (c) obtaining an antibody that dissociates from the antigen/antibody complex in step (b);   (d) obtaining nucleic acid encoding the antibody obtained in step (c); and   (e) producing the antibody by expressing the nucleic acid obtained in step (d).   
     
     
         83 . A method of producing a calcium concentration-dependent antibody, the method comprising:
 (a) contacting an antigen with an antibody or a library of antibodies under a low calcium concentration condition, wherein the low calcium concentration is an ionized calcium concentration of 0.1 μM to 30 μM;   (b) selecting an antibody that does not bind to the antigen in step (a);   (c) allowing the antibody selected in step (b) to bind to the antigen under a high calcium concentration condition, wherein the high calcium concentration is an ionized calcium concentration of 100 μM to 10 mM;   (d) selecting an antibody that binds to the antigen in step (c);   (e) obtaining nucleic acid encoding the antibody obtained in step (d); and   (f) producing the antibody by expressing the nucleic acid obtained in step (e).   
     
     
         84 . The method of  claim 82 , further comprising altering the coding sequence of the nucleic acid to encode a modified antibody, wherein the human FcRn-binding activity of the modified antibody at a neutral pH is higher than that of the antibody that was not so modified. 
     
     
         85 . The method of  claim 82 , further comprising altering the coding sequence of the nucleic acid to encode a modified antibody, wherein the antigen-binding activity of the modified antibody at an acidic pH is (1) decreased compared to the antigen-binding activity at the acidic pH of the antibody that was not so modified, and (2) lower than the antigen-binding activity of the modified antibody at neutral pH. 
     
     
         86 . The method of  claim 83 , further comprising altering the coding sequence of the nucleic acid to encode a modified antibody, wherein the human FcRn-binding activity of the modified antibody at a neutral pH is higher than that of the antibody that was not so modified. 
     
     
         87 . The method of  claim 83 , further comprising altering the coding sequence of the nucleic acid to encode a modified antibody, wherein the antigen-binding activity of the modified antibody at an acidic pH is (1) decreased compared to the antigen-binding activity at the acidic pH of the antibody that was not so modified, and (2) lower than the antigen-binding activity of the modified antibody at neutral pH. 
     
     
         88 . A pharmaceutical composition comprising the antibody of  claim 75  and a pharmaceutically acceptable carrier. 
     
     
         89 . A method of screening for a calcium concentration-dependent antibody, the method comprising:
 (a) contacting an antigen with an antibody or library of antibodies under a high calcium concentration condition, to produce an antigen/antibody complex, wherein the high calcium concentration is an ionized calcium concentration of 100 μM to 10 mM;   (b) placing the antigen/antibody complex under a low calcium concentration condition, wherein the low calcium concentration is an ionized calcium concentration of 0.1 μM to 30 μM; and   (c) obtaining an antibody that dissociates from the antigen/antibody complex in step (b).   
     
     
         90 . A method of screening for a calcium concentration-dependent antibody, the method comprising:
 (a) contacting an antigen with an antibody or a library of antibodies under a low calcium concentration condition, wherein the low calcium concentration is an ionized calcium concentration of 0.1 μM to 30 μM;   (b) selecting an antibody that does not bind to the antigen in step (a);   (c) allowing the antibody selected in step (b) to bind to the antigen under a high calcium concentration condition, wherein the high calcium concentration is an ionized calcium concentration of 100 μM to 10 mM; and   (d) obtaining an antibody that binds to the antigen in step (c).   
     
     
         91 . A method for promoting antigen uptake into a cell in a subject in need thereof, the method comprising administering the antibody of  claim 75  to the subject. 
     
     
         92 . A method for reducing the plasma concentration of an antigen in a subject in need thereof, the method comprising administering the antibody of  claim 75  to the subject. 
     
     
         93 . The method of  claim 91 , wherein the antigen-binding activity of the antibody is lower at acidic pH than at neutral pH. 
     
     
         94 . The method of  claim 92 , wherein the antigen-binding activity of the antibody is lower at acidic pH than at neutral pH.