title: Asymmetrical Fc engineering greatly enhances antibody-dependent cellular cytotoxicity (ADCC) effector function and stability of the modified antibodies.
abstract: Antibody-dependent cellular cytotoxicity (ADCC) is mediated through the engagement of the Fc segment of antibodies with Fcγ receptors (FcγRs) on immune cells upon binding of tumor or viral antigen. The co-crystal structure of FcγRIII in complex with Fc revealed that Fc binds to FcγRIII asymmetrically with two Fc chains contacting separate regions of the FcγRIII by utilizing different residues. To fully explore this asymmetrical nature of the Fc-FcγR interaction, we screened more than 9,000 individual clones in Fc heterodimer format in which different mutations were introduced at the same position of two Fc chains using a high throughput competition AlphaLISA® assay. To this end, we have identified a panel of novel Fc variants with significant binding improvement to FcγRIIIA (both Phe-158 and Val-158 allotypes), increased ADCC activity in vitro, and strong tumor growth inhibition in mice xenograft human tumor models. Compared with previously identified Fc variants in conventional IgG format, Fc heterodimers with asymmetrical mutations can achieve similar or superior potency in ADCC-mediated tumor cell killing and demonstrate improved stability in the CH2 domain. Fc heterodimers also allow more selectivity toward activating FcγRIIA than inhibitory FcγRIIB. Afucosylation of Fc variants further increases the affinity of Fc to FcγRIIIA, leading to much higher ADCC activity. The discovery of these Fc variants will potentially open up new opportunities of building the next generation of therapeutic antibodies with enhanced ADCC effector function for the treatment of cancers and infectious diseases.
authors: From the Departments of Therapeutic Discovery and.
authors: Zhi
authors: Z
authors: Liu
authors: Kannan
authors: K
authors: Gunasekaran
authors: Wei
authors: W
authors: Wang
authors: Vladimir
authors: V
authors: Razinkov
authors: Laura
authors: L
authors: Sekirov
authors: Esther
authors: E
authors: Leng
authors: Heather
authors: H
authors: Sweet
authors: Ian
authors: I
authors: Foltz
authors: Monique
authors: M
authors: Howard
authors: Anne-Marie
authors: AM
authors: Rousseau
authors: Carl
authors: C
authors: Kozlosky
authors: William
authors: W
authors: Fanslow
authors: Wei
authors: W
authors: Yan
mesh_terms: D000818:Animals; D000912:Antibodies, Neoplasm / Q000235:genetics / Q000276:immunology / Q000494:pharmacology; D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D007074:Immunoglobulin G / Q000235:genetics / Q000276:immunology / Q000494:pharmacology; D051379:Mice; D016513:Mice, SCID; D009154:Mutation; D009369:Neoplasms; D015202:Protein Engineering; D017452:Receptors, IgG / Q000235:genetics / Q000276:immunology*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000912:Antibodies, Neoplasm; C496124:FCGR3A protein, human; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D017452:Receptors, IgG
keywords: Antibody Engineering; Cancer Therapy; Cell Death; FCγ Receptors; NK Cells