Compositions and methods for producing enhanced antibodies

Abstract

The invention provides a Vitaxin antibody and a LM609 grafted antibody exhibiting selective binding affinity to α c β 3 . The Vitaxin antibody consists of at least one Vitaxin heavy chain polypeptide and at least one Vitaxin light chain polypeptide or functional fragments thereof. Also provided are the Vitaxin heavy and light chain polypeptides and functional fragments. The LM609 grafted antibody consists of at least one CDR grafted heavy chain polypeptide and at least one CDR grafted light chain polypeptide or functional fragment thereof. The invention additionally provides a high affinity LM609 grafted antibody comprising one or more CDRs having at least one amino acid substitution, where the α v β 3 binding activity of the high affinity LM609 grafted antibody is enhanced. Nucleic acids encoding Vitaxin and LM609 grafted heavy and light chains as well as nucleic acids encoding the parental non-human antibody LM609 are additionally provided. Functional fragments of such encoding nucleic acids are similarly provided. The invention also provides a method of inhibiting a function of α v β 3 . The method consists of contacting α v β 3 with Vitaxin or a LM609 grafted antibody or functional fragments thereof under conditions which allow binding to α v β 3 . Finally, the invention provides for a method of treating an α v β 3 -mediated disease. The method consists of administering an effective amount of Vitaxin or a LM609 grafted antibody or functional fragment thereof under conditions which allow binding to α v β 3 .

1 . A method for producing an enhanced antibody, or functional fragment thereof, comprising: 
 (a) modifying a parent antibody, or functional fragment thereof;    (b) obtaining one or more variant antibodies, or functional fragments thereof, said one or more variant antibodies, or functional fragments thereof, comprising one or more amino acid substitutions in one or more variable regions compared to said parent antibody, and    (c) measuring the association rate constant (k on ) of said one or more variant antibodies, or functional fragments thereof, to an antigen, wherein a variant antibody, or functional fragment thereof, having an association rate to an antigen that is 4-fold higher or greater compared to the rate of said parent antibody binding to said antigen is an enhanced antibody, or functional fragment thereof.    
     
     
         2 . The method of  claim 1 , further comprising isolating said enhanced antibody, or functional fragment thereof.  
     
     
         3 . The method of  claim 1 , wherein said one or more amino acid substitutions are in one or more CDRs.  
     
     
         4 . The method of  claim 1 , wherein said one or more amino acid substitutions are in one or more framework regions.  
     
     
         5 . The method of  claim 1 , wherein said amino acid substitutions are in one or more CDRs and one or more framework regions.  
     
     
         6 . The method of  claim 1 , wherein said enhanced antibody, or functional fragment thereof, has an association rate constant (k on ) that is 6.8×10 5  M −1  sec −1  or higher.  
     
     
         7 . The method of  claim 6 , wherein said enhanced antibody, or functional fragment thereof, has an association constant (K a ) that is 2.0×10 9  M −1  or higher.  
     
     
         8 . The method of  claim 1 , wherein said enhanced antibody, or functional fragment thereof, is a grafted antibody, or functional fragment thereof.