title: A high affinity recombinant antibody to the human EphA3 receptor with enhanced ADCC activity.
abstract: EphA3 is expressed in solid tumors and leukemias and is an attractive target for the therapy. We have generated a panel of Humaneered® antibodies to the ligand-binding domain using a Fab epitope-focused library that has the same specificity as monoclonal antibody mIIIA4. A high-affinity antibody was selected that competes with the mIIIA4 antibody for binding to EphA3 and has an improved affinity of ∼1 nM. In order to generate an antibody with potent cell-killing activity the variable regions were assembled with human IgG1k constant regions and expressed in a Chinese hamster ovary (CHO) cell line deficient in fucosyl transferase. Non-fucosylated antibodies have been reported to have enhanced binding affinity for the IgG receptor CD16a (FcγRIIIa). The affinity of the antibody for recombinant CD16a was enhanced approximately 10-fold. This resulted in enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) activity against EphA3-expressing leukemic cells, providing a potent antibody for the evaluation as a therapeutic agent.
authors.affiliation: KaloBios Pharmaceuticals , South San Francisco, CA , USA.
authors.forename: Nenad
authors.initials: N
authors.lastname: Tomasevic
authors.forename: Kenneth
authors.initials: K
authors.lastname: Luehrsen
authors.forename: Mark
authors.initials: M
authors.lastname: Baer
authors.forename: Varghese
authors.initials: V
authors.lastname: Palath
authors.forename: David
authors.initials: D
authors.lastname: Martinez
authors.forename: Jason
authors.initials: J
authors.lastname: Williams
authors.forename: Christina
authors.initials: C
authors.lastname: Yi
authors.forename: Swathi
authors.initials: S
authors.lastname: Sujatha-Bhaskar
authors.forename: Rohini
authors.initials: R
authors.lastname: Lanke
authors.forename: John
authors.initials: J
authors.lastname: Leung
authors.forename: Wendy
authors.initials: W
authors.lastname: Ching
authors.forename: Andreia
authors.initials: A
authors.lastname: Lee
authors.forename: Lu
authors.initials: L
authors.lastname: Bai
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Yarranton
authors.forename: Christopher
authors.initials: C
authors.lastname: Bebbington
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000276:immunology*; D000915:Antibody Affinity; D000920:Antibody-Dependent Cell Cytotoxicity; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000276:immunology; D008253:Macaca mulatta; D008969:Molecular Sequence Data; D036121:Receptor, EphA3 / Q000276:immunology*; D017452:Receptors, IgG / Q000276:immunology; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D007141:Immunoglobulin Fc Fragments; D017452:Receptors, IgG; D011994:Recombinant Proteins; D036121:Receptor, EphA3
keywords: ADCC; EphA3; Humaneered; leukemia; non-fucosylated