ANTIBODIES WITH pH DEPENDENT ANTIGEN BINDING

Abstract

The present invention relates to antibodies with pH dependent binding to its antigen such that the affinity for antigen binding at physiological pH (i.e., pH 7.4) is greater than at endosomal pH (i.e., pH 6.0 or 5.5). In other words, the KD or koff ratio at pH 5.5/pH 7.4 or at pH 6.0/pH 7.4 is more than, or ranges between, 2, 3, 4, 8, 10, 16, 20, 30, 40, or 100 or more. Such pH dependent antibodies preferentially dissociate from the antigen in the endosome. This can increase antibody half life, as compared to antibodies with equivalent KDs at pH 7.4 but with no pH dependent binding, when the antigen is one that undergoes antigen-mediated clearance (e.g., PCSK9). Antibodies with pH dependent binding can decrease total antigen half life when the antigen undergoes reduced clearance when bound to antibody (e.g., IL6). Antibodies with pH dependent binding can also prolong the decrease in antigen which is not antibody-bound. This can be important when antagonizing a target antigen typically present at high levels (e.g., IgE, DKK1, C5 and SOST). In addition, such antibodies can increase antigen half life when the antigen is a receptor and the receptor has increased clearance when bound to antibody (e.g., GMCSF receptor).

1 - 11 . (canceled) 
     
     
         12 . A method of extending interval dosing and/or decreasing the therapeutic dose for treating a patient with a therapeutic antibody, said method comprising administering to the patient a therapeutically effective amount of the antibody, wherein one or more amino acid substitutions have been engineered into one or more complementarity determining regions of said antibody as compared to the original unsubstituted antibody such that said antibody specifically binds an antigen with higher affinity at pH 7.4 than at pH 6.0, wherein the K D  ratio and the k off  ratio at pH 6.0/pH 7.4 at 25° C. is 2, 3, 4, 8, 10, 16, or more, and the K D  ratio and/or the k off  ratio is higher as compared to the unsubstituted antibody, wherein the antigen is soluble and not membrane bound, and wherein said antibody prolongs the antibody-mediated decrease in antigen that is not antibody-bound as compared to said unsubstituted antibody. 
     
     
         13 - 23 . (canceled) 
     
     
         24 . The method of  claim 12 , wherein the at least one amino acid substitution comprises at least one histidine substitution. 
     
     
         25 . The method of  claim 12 , wherein the antigen is not interleukin-6 receptor. 
     
     
         26 . The method of  claim 12 , wherein said antibody with pH dependent binding is an antibody drug conjugate, mediates antibody dependent cell-mediated cytotoxicity (ADCC), and/or mediates complement-dependent cytotoxicity (CDC). 
     
     
         27 . The method of  claim 12 , wherein pH dependent binding of the antibody has the K D  ratio and/or k off  ratio at pH 6.0/pH 7.4 and at 25° C. which is 20, 30, 40, 100 or more. 
     
     
         28 . The method of  claim 27 , wherein the antigen is PCSK9, IgE, C5, or DKK1. 
     
     
         29 . The method of  claim 28 , wherein the antigen is PCSK9 and the pH dependent binding of the antibody to the antigen at pH 7.4 and at 25° C. has a K D  ranging between 0.01 nM and 100 nM and a K D  ratio of 10, 30, 100 or more. 
     
     
         30 . The method of  claim 29 , wherein the binding of the antibody to antigen at pH 7.4 and at 25° C. has a K D  ranging between 0.1 nM to 10 nM. 
     
     
         31 . The method of  claim 28 , wherein the antigen is C5 and the pH dependent binding of the antibody to the antigen at pH 7.4 and 25C has a K D  ranging between 0.1 nM and 100 nM and the k off  ratio at pH 6.0/pH 7.4 at 25° C. is 10, 30 or more. 
     
     
         32 . The method of  claim 31 , wherein the k off  ratio is 30 or more. 
     
     
         33 . A method of making an antibody with prolonged half-life by regulating antibody-antigen binding affinity in a pH dependent manner, said method comprising engineering at least one amino acid substitution into the complementarity determining region of said antibody wherein said antibody specifically binds an antigen with higher affinity at pH 7.4 than at pH 6.0, wherein the K D  ratio and the k off  ratio at pH 6.0/pH 7.4 and at 25° C. is 2, 3, 4, 8, 10, 16, or more, and wherein said antigen is soluble and not membrane bound. 
     
     
         34 . The method of  claim 33 , wherein the at least one amino acid substitution comprises at least one histidine substitution. 
     
     
         35 . The method of  claim 33 , wherein the antigen is not interleukin-6 receptor. 
     
     
         36 . The method of  claim 33 , wherein the antigen is PCSK9, IgE, C5, or DKK1.