%0 Journal Article %A Jung, Sang Taek %A Kelton, William %A Kang, Tae Hyun %A Ng, Daphne T.W. %A Andersen, Jan Terje %A Sandlie, Inger %A Sarkar, Casim A. %A Georgiou, George %D 2013 %T Effective Phagocytosis of Low Her2 Tumor Cell Lines with Engineered, Aglycosylated IgG Displaying High FcγRIIa Affinity and Selectivity %U https://acs.figshare.com/articles/journal_contribution/Effective_Phagocytosis_of_Low_Her2_Tumor_Cell_Lines_with_Engineered_Aglycosylated_IgG_Displaying_High_Fc_RIIa_Affinity_and_Selectivity/2442640 %R 10.1021/cb300455f.s001 %2 https://acs.figshare.com/ndownloader/files/4085299 %K glycosylated trastuzumab %K IgG display system %K receptor affinity %K Fc γRs %K 2 Tumor Cell Lines %K effector function %K affinity Fc γRIIa allele %K aglycosylated Fc domains %K antibody IgG Fc domain %K Fc domains %K tumor cell phagocytosis %K residue N 297 %K future engineering %K Fc domain %K Effective Phagocytosis %K High Fc γRIIa Affinity %K acid substitutions %K Aglycosylated IgG %K Fc γRIIb %X Glycans anchored to residue N297 of the antibody IgG Fc domain are critical in mediating binding toward FcγRs to direct both adaptive and innate immune responses. However, using a full length bacterial IgG display system, we have isolated aglycosylated Fc domains with mutations that confer up to a 160-fold increase in the affinity toward the low affinity FcγRIIa-R131 allele as well as high selectivity against binding to the remarkably homologous human inhibitory receptor, FcγRIIb. The mutant Fc domain (AglycoT-Fc1004) contained a total of 5 amino acid substitutions that conferred an activating to inhibitory ratio of 25 (A/I ratio; FcyRIIa-R131:FcγRIIb). Incorporation of this engineered Fc into trastuzumab, an anti-Her2 antibody, resulted in a 75% increase in tumor cell phagocytosis by macrophages compared to that of the parental glycosylated trastuzumab with both medium and low Her2-expressing cancer cells. A mathematical model has been developed to help explain how receptor affinity and the A/I ratio relate to improved antibody dependent cell-mediated phagocytosis. Our model provides guidelines for the future engineering of Fc domains with enhanced effector function. %I ACS Publications