title: Antibody Fc engineering improves frequency and promotes kinetic boosting of serial killing mediated by NK cells.
abstract: The efficacy of most therapeutic monoclonal antibodies (mAbs) targeting tumor antigens results primarily from their ability to elicit potent cytotoxicity through effector-mediated functions. We have engineered the fragment crystallizable (Fc) region of the immunoglobulin G (IgG) mAb, HuM195, targeting the leukemic antigen CD33, by introducing the triple mutation Ser293Asp/Ala330Leu/Ile332Glu (DLE), and developed Time-lapse Imaging Microscopy in Nanowell Grids to analyze antibody-dependent cell-mediated cytotoxicity kinetics of thousands of individual natural killer (NK) cells and mAb-coated target cells. We demonstrate that the DLE-HuM195 antibody increases both the quality and the quantity of NK cell-mediated antibody-dependent cytotoxicity by endowing more NK cells to participate in cytotoxicity via accrued CD16-mediated signaling and by increasing serial killing of target cells. NK cells encountering targets coated with DLE-HuM195 induce rapid target cell apoptosis by promoting simultaneous conjugates to multiple target cells and induce apoptosis in twice the number of target cells within the same period as the wild-type mAb. Enhanced target killing was also associated with increased frequency of NK cells undergoing apoptosis, but this effect was donor-dependent. Antibody-based therapies targeting tumor antigens will benefit from a better understanding of cell-mediated tumor elimination, and our work opens further opportunities for the therapeutic targeting of CD33 in the treatment of acute myeloid leukemia.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX;
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Romain
authors.affiliation: Division of Pediatrics, University of Texas M.D. Anderson Cancer Center, Houston, TX;
authors.forename: Vladimir
authors.initials: V
authors.lastname: Senyukov
authors.affiliation: Department of Electrical Engineering, University of Houston, Houston, TX; and.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Rey-Villamizar
authors.affiliation: Department of Electrical Engineering, University of Houston, Houston, TX; and.
authors.forename: Amine
authors.initials: A
authors.lastname: Merouane
authors.affiliation: Department of Chemical Engineering, Institute for Cell and Molecular Biology, University of Texas, Austin, TX.
authors.forename: William
authors.initials: W
authors.lastname: Kelton
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX;
authors.forename: Ivan
authors.initials: I
authors.lastname: Liadi
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX;
authors.forename: Ankit
authors.initials: A
authors.lastname: Mahendra
authors.affiliation: Department of Chemical Engineering, Institute for Cell and Molecular Biology, University of Texas, Austin, TX.
authors.forename: Wissam
authors.initials: W
authors.lastname: Charab
authors.affiliation: Department of Chemical Engineering, Institute for Cell and Molecular Biology, University of Texas, Austin, TX.
authors.forename: George
authors.initials: G
authors.lastname: Georgiou
authors.affiliation: Department of Electrical Engineering, University of Houston, Houston, TX; and.
authors.forename: Badrinath
authors.initials: B
authors.lastname: Roysam
authors.affiliation: Division of Pediatrics, University of Texas M.D. Anderson Cancer Center, Houston, TX;
authors.forename: Dean A
authors.initials: DA
authors.lastname: Lee
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX;
authors.forename: Navin
authors.initials: N
authors.lastname: Varadarajan
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000920:Antibody-Dependent Cell Cytotoxicity; D002478:Cells, Cultured; D005818:Genetic Engineering; D057809:HEK293 Cells; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000235:genetics / Q000276:immunology*; D007074:Immunoglobulin G / Q000235:genetics / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology*; D016296:Mutagenesis; D061251:Primary Cell Culture; D059008:Time-Lapse Imaging
chemical_list: D000911:Antibodies, Monoclonal; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G