title: Novel asymmetrically engineered antibody Fc variant with superior FcγR binding affinity and specificity compared with afucosylated Fc variant.
abstract: Fc engineering is a promising approach to enhance the antitumor efficacy of monoclonal antibodies (mAbs) through antibody-dependent cell-mediated cytotoxicity (ADCC). Glyco- and protein-Fc engineering have been employed to enhance FcγR binding and ADCC activity of mAbs; the drawbacks of previous approaches lie in their binding affinity to both FcγRIIIa allotypes, the ratio of activating FcγR binding to inhibitory FcγR binding (A/I ratio) or the melting temperature (T(M)) of the C(H)2 domain. To date, no engineered Fc variant has been reported that satisfies all these points. Herein, we present a novel Fc engineering approach that introduces different substitutions in each Fc domain asymmetrically, conferring optimal binding affinity to FcγR and specificity to the activating FcγR without impairing the stability. We successfully designed an asymmetric Fc variant with the highest binding affinity for both FcγRIIIa allotypes and the highest A/I ratio compared with previously reported symmetrically engineered Fc variants, and superior or at least comparable in vitro ADCC activity compared with afucosylated Fc variants. In addition, the asymmetric Fc engineering approach offered higher stability by minimizing the use of substitutions that reduce the T(M) of the C(H)2 domain compared with the symmetric approach. These results demonstrate that the asymmetric Fc engineering platform provides best-in-class effector function for therapeutic antibodies against tumor antigens.
authors: Research Division, Chugai Pharmaceutical Co., Ltd., Tokyo, Japan.
authors: Futa
authors: F
authors: Mimoto
authors: Tomoyuki
authors: T
authors: Igawa
authors: Taichi
authors: T
authors: Kuramochi
authors: Hitoshi
authors: H
authors: Katada
authors: Shojiro
authors: S
authors: Kadono
authors: Takayuki
authors: T
authors: Kamikawa
authors: Meiri
authors: M
authors: Shida-Kawazoe
authors: Kunihiro
authors: K
authors: Hattori
mesh_terms: D019943:Amino Acid Substitution; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000915:Antibody Affinity; D000918:Antibody Specificity; D000920:Antibody-Dependent Cell Cytotoxicity; D002460:Cell Line; D005643:Fucose / Q000378:metabolism; D014644:Genetic Variation; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D015202:Protein Engineering / Q000379:methods*; D017452:Receptors, IgG / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; C496124:FCGR3A protein, human; D007141:Immunoglobulin Fc Fragments; D017452:Receptors, IgG; D005643:Fucose
keywords: A/I ratio; ADCC; Fc engineering; FcγR; antibody engineering