title: Structure-Directed and Tailored Diversity Synthetic Antibody Libraries Yield Novel Anti-EGFR Antagonists.
abstract: We tested whether grafting an interaction domain into the hypervariable loop of a combinatorial antibody library could promote targeting to a specific epitope. Formation of the epidermal growth factor receptor (EGFR) signaling heterodimer involves extensive contacts mediated by a "dimerization loop." We grafted the dimerization loop into the third hypervariable loop of a synthetic antigen-binding fragment (Fab) library and diversified other loops using a tailored diversity strategy. This structure-directed Fab library and a naı̈ve synthetic Fab library were used to select Fabs against EGFR. Both libraries yielded high affinity Fabs that bound to overlapping epitopes on cell-surface EGFR, inhibited receptor activation, and targeted epitopes distinct from those of cetuximab and panitumumab. Epitope mapping experiments revealed complex sites of interaction, comprised of domains I and II but not exclusively localized to the receptor dimerization loop. These results validate the grafting approach for designing Fab libraries and also underscore the versatility of naı̈ve synthetic libraries.
authors.affiliation: Banting and Best Department of Medical Research and Donnelly Centre for Cellular and Biomolecular Research, University of Toronto , Toronto, Ontario, Canada M5S 3E1.
authors.forename: Shane
authors.identifier: 0000-0003-4785-4508
authors.initials: S
authors.lastname: Miersch
authors.affiliation: Department of Biochemistry, University of Saskatchewan , Saskatoon, Saskatchewan, Canada S7N 5E5.
authors.forename: Bharathikumar Vellalore
authors.initials: BV
authors.lastname: Maruthachalam
authors.affiliation: Department of Pathology and Lab Medicine, University of Saskatchewan , Saskatoon, Saskatchewan, Canada S7N 0W8.
authors.forename: C Ronald
authors.initials: CR
authors.lastname: Geyer
authors.affiliation: Banting and Best Department of Medical Research and Donnelly Centre for Cellular and Biomolecular Research, University of Toronto , Toronto, Ontario, Canada M5S 3E1.
authors.forename: Sachdev S
authors.initials: SS
authors.lastname: Sidhu
mesh_terms: D000906:Antibodies / Q000737:chemistry*; D000915:Antibody Affinity; D001665:Binding Sites; D022801:Complementarity Determining Regions; D018604:Epitope Mapping; D000939:Epitopes; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000276:immunology*; D006801:Humans; D007140:Immunoglobulin Fab Fragments; D019151:Peptide Library; D015202:Protein Engineering / Q000379:methods*
chemical_list: D000906:Antibodies; D022801:Complementarity Determining Regions; D000939:Epitopes; D007140:Immunoglobulin Fab Fragments; D019151:Peptide Library; D066246:ErbB Receptors