Acceptor framework for cdr grafting

Abstract

The present invention relates to an antibody acceptor framework and to methods for grafting non-human antibodies, e.g., rabbit antibodies, using a particularly well suited antibody acceptor framework. Antibodies generated by the methods of the invention are useful in a variety of diagnostic and therapeutic applications.

1 . A human heavy chain acceptor framework comprising SEQ ID NO: 1. 
     
     
         2 . The human heavy chain acceptor framework of  claim 1 , comprising an amino acid substitution at position 12, 103, and/or 144 (Aho numbering). 
     
     
         3 . The human heavy chain acceptor framework of  claim 2 , wherein the substitution is
 (a) Serine (S) at position 12;   (b) Serine (S) or Threonine (T) at position 103; and/or   (c) Serine (S) or Threonine (T) at position 144.   
     
     
         4 . An isolated nucleic acid encoding the acceptor framework of  claim 1 . 
     
     
         5 . A vector comprising the nucleic acid of  claim 4 . 
     
     
         6 . A host cell comprising the vector of  claim 5 . 
     
     
         7 . An immunobinder specific to a desired antigen comprising:
 (a) a light chain acceptor framework comprising variable light chain CDRs of a lagomorph immunobinder; and   (b) human heavy chain acceptor framework of  claim 1  comprising variable heavy chain CDRs of a lagomorph immunobinder.   
     
     
         8 . The immunobinder of  claim 7 , wherein the light chain acceptor framework has at least 85% identity to SEQ ID NO: 2. 
     
     
         9 . The immunobinder of  claim 7 , further comprising a linker sequence that links the variable light chain framework and the heavy chain acceptor framework, wherein the linker sequence is SEQ ID NO: 4. 
     
     
         10 . The immunobinder of  claim 7 , further comprising donor framework residues involved in antigen binding. 
     
     
         11 . The immunobinder of  claim 7 , wherein the immunobinder is a scFv antibody, a full-length immunoglobulin or a Fab fragment. 
     
     
         12 . A method of humanizing a rabbit immunobinder, the method comprising:
 (a) grafting at least one heavy chain CDR of the group consisting of CDR H1, CDR H2 and CDR H3 sequences from a donor rabbit immunobinder into the human heavy chain acceptor framework of  claim 1 ; and   (b) grafting at least one light chain CDR of the group consisting of CDR L1, CDR L2 and CDR L3 sequences from a donor rabbit immunobinder into a human light chain acceptor framework into a light chain acceptor framework has at least 85% identity to SEQ ID NO: 2.   
     
     
         13 . The method of  claim 12 , further comprising substituting framework residues in one or both of the human heavy chain acceptor framework and the human light chain framework with framework residues of the donor rabbit immunobinder. 
     
     
         14 . The method of  claim 12 , wherein the heavy chain acceptor framework has a substitution at one or more of heavy chain amino positions 12, 103 and 144 (AHo numbering). 
     
     
         15 . The method of  claim 14 , wherein the substitution at one or more of positions 12, 103 and 144 are selected from the group consisting of:
 (a) Serine (S) at position 12;   (b) Threonine (T) at position 103; and   (c) Threonine (T) at position 144.   
     
     
         16 . An immunobinder humanized according to the method of  claim 12 .