Increasing FcγRIIa affinity of an FcγRIII-optimized anti-EGFR antibody restores neutrophil-mediated cytotoxicity.
Antibody-dependent cell-mediated cytotoxicity (ADCC) has been suggested as an essential mechanism for the in vivo activity of cetuximab, an epidermal growth factor receptor (EGFR)-targeting therapeutic antibody. Thus, enhancing the affinity of human IgG1 antibodies to natural killer (NK) cell-expressed FcγRIIIa by glyco- or protein-engineering of their Fc portion has been demonstrated to improve NK cell-mediated ADCC and to represent a promising strategy to improve antibody therapy. However, human polymorphonuclear (PMN) effector cells express the highly homologous FcγRIIIb isoform, which is described to be ineffective in triggering ADCC. Here, non-fucosylated or protein-engineered anti-EGFR antibodies with optimized FcγRIIIa affinities demonstrated the expected benefit in NK cell-mediated ADCC, but did not mediate ADCC by PMN, which could be restored by FcγRIIIb blockade. Furthermore, eosinophils and PMN from paroxysmal nocturnal hemoglobinuria patients that expressed no or low levels of FcγRIIIb mediated effective ADCC with FcγRIII-optimized anti-EGFR antibody. Additional experiments with double FcγRIIa/FcγRIII-optimized constructs demonstrated enhanced PMN-mediated ADCC compared with single FcγRIII-optimized antibody. In conclusion, our data demonstrate that FcγRIIIb engagement impairs PMN-mediated ADCC activity of FcγRIII-optimized anti-EGFR antibodies, while further optimization of FcγRIIa binding significantly restores PMN recruitment.
Division of Stem Cell Transplantation and Immunotherapy; 2nd Department of Medicine; University Hospital Schleswig-Holstein and Christian-Albrechts-University; Kiel, Germany.
Stefanie
S
Derer
Division of Stem Cell Transplantation and Immunotherapy; 2nd Department of Medicine; University Hospital Schleswig-Holstein and Christian-Albrechts-University; Kiel, Germany.
Pia
P
Glorius
Division of Stem Cell Transplantation and Immunotherapy; 2nd Department of Medicine; University Hospital Schleswig-Holstein and Christian-Albrechts-University; Kiel, Germany.
Martin
M
Schlaeth
Division of Stem Cell Transplantation and Immunotherapy; 2nd Department of Medicine; University Hospital Schleswig-Holstein and Christian-Albrechts-University; Kiel, Germany.
Stefan
S
Lohse
Division of Stem Cell Transplantation and Immunotherapy; 2nd Department of Medicine; University Hospital Schleswig-Holstein and Christian-Albrechts-University; Kiel, Germany.
Katja
K
Klausz
Xencor, Inc; Monrovia, CA USA.
Umesh
U
Muchhal
Xencor, Inc; Monrovia, CA USA.
John R
JR
Desjarlais
Division of Stem Cell Transplantation and Immunotherapy; 2nd Department of Medicine; University Hospital Schleswig-Holstein and Christian-Albrechts-University; Kiel, Germany.
Andreas
A
Humpe
Division of Stem Cell Transplantation and Immunotherapy; 2nd Department of Medicine; University Hospital Schleswig-Holstein and Christian-Albrechts-University; Kiel, Germany.
Thomas
T
Valerius
Division of Stem Cell Transplantation and Immunotherapy; 2nd Department of Medicine; University Hospital Schleswig-Holstein and Christian-Albrechts-University; Kiel, Germany.
Matthias
M
Peipp
D061067:Antibodies, Monoclonal, Humanized / Q000235:genetics / Q000378:metabolism*; D000915:Antibody Affinity / Q000235:genetics; D000920:Antibody-Dependent Cell Cytotoxicity / Q000235:genetics; D002478:Cells, Cultured; D000068818:Cetuximab; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D004804:Eosinophils / Q000276:immunology*; D066246:ErbB Receptors / Q000276:immunology; D006031:Glycosylation; D006457:Hemoglobinuria, Paroxysmal / Q000276:immunology* / Q000628:therapy*; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000235:genetics; D007074:Immunoglobulin G / Q000235:genetics / Q000378:metabolism*; D007167:Immunotherapy / Q000379:methods* / Q000639:trends; D009504:Neutrophils / Q000276:immunology*; D011110:Polymorphism, Genetic; D015202:Protein Engineering; D017452:Receptors, IgG / Q000235:genetics / Q000276:immunology / Q000378:metabolism
D061067:Antibodies, Monoclonal, Humanized; C496124:FCGR3A protein, human; C080568:Fc gamma receptor IIA; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D017452:Receptors, IgG; C512478:EGFR protein, human; D066246:ErbB Receptors; D000068818:Cetuximab
ADCC; EGFR; Fc-engineering; FcγRIII; FcγRIIIb; FcγRIIa; PMN; cetuximab