title: Antibody humanization using monovalent phage display.
abstract: Antibody humanization often requires the replacement of key residues in the framework regions with corresponding residues from the parent non-human antibody. These changes are in addition to grafting of the antigen-binding loops. Although guided by molecular modeling, assessment of which framework changes are beneficial to antigen binding usually requires the analysis of many different antibody mutants. Here we describe a phage display method for optimizing the framework of humanized antibodies by random mutagenesis of important framework residues. We have applied this method to humanization of the anti-vascular endothelial growth factor murine monoclonal antibody A4.6.1. Affinity panning of a library of humanized A4.6.1 antibody mutants led to the selection of one variant with greater than 125-fold enhanced affinity for antigen relative to the initial humanized antibody with no framework changes. A single additional mutation gave a further 6-fold improvement in binding. The affinity of this variant, 9.3 nM, was only 6-fold weaker than that of a murine/human chimera of A4.6.1. This method provides a general means of rapidly selecting framework mutations that improve the binding of humanized antibodies to their cognate antigens and may prove an attractive alternative to current methods of framework optimization based on cycles of site-directed mutagenesis.
authors.affiliation: Department of Protein Engineering, Genentech, Inc., South San Francisco, California 94080, USA.
authors.forename: M
authors.initials: M
authors.lastname: Baca
authors.forename: L G
authors.initials: LG
authors.lastname: Presta
authors.forename: S J
authors.initials: SJ
authors.lastname: O'Connor
authors.forename: J A
authors.initials: JA
authors.lastname: Wells
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis* / Q000737:chemistry*; D001435:Bacteriophages; D001483:Base Sequence; D001666:Binding Sites, Antibody; D003001:Cloning, Molecular / Q000379:methods; D003062:Codon; D016228:Endothelial Growth Factors / Q000276:immunology*; D004926:Escherichia coli; D015723:Gene Library; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000096:biosynthesis* / Q000737:chemistry*; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis / Q000737:chemistry; D008222:Lymphokines / Q000276:immunology*; D051379:Mice; D008961:Models, Structural; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009838:Oligodeoxyribonucleotides; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: D000911:Antibodies, Monoclonal; D003062:Codon; D016228:Endothelial Growth Factors; D007140:Immunoglobulin Fab Fragments; D007143:Immunoglobulin Heavy Chains; D008222:Lymphokines; D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors