title: Bispecific antibody-dependent cellular cytotoxicity of HER2/neu-overexpressing tumor cells by Fc gamma receptor type I-expressing effector cells.
abstract: A bispecific antibody, MDX-H210, was developed to target cytotoxic effector cells expressing Fc gamma receptor type I (Fc gammaRI, CD64) to HER2/neu-overexpressing tumor cells. HER2/neu is an appropriate target for immunotherapy due to the high level of expression of this proto-oncogene in a variety of malignancies. The expression of Fc gammaRI is limited primarily to cytotoxic immune cells, including monocytes, macrophages, and cytokine-activated polymorphonuclear (PMN) cells. Therefore, tumor cells bound with MDX-H210 can be selectively recognized by effector cells with cytotoxic potential. MDX-H210 was prepared by chemical conjugation of Fab' fragments derived from the HER2/neu-specific monoclonal antibody, 520C9, and the Fc gammaRI-specific monoclonal antibody, H22. This bispecific molecule demonstrated specific, dose-dependent, and saturable binding to both HER2/neu- and Fc gammaRI-expressing cells. A solid-phase immunoassay that demonstrated simultaneous and specific binding to both antigens was used to confirm the bispecific nature of MDX-H210. Monocytes and PMN cells mediated MDX-H210-dependent lysis of HER2/neu-overexpressing cell lines derived from breast, ovarian, and lung carcinomas. IFN-gamma treatment of monocytes enhanced antibody-dependent cellular cytotoxicity, whereas IFN-gamma and granulocyte colony-stimulating factor were required for PMN cell-mediated tumor cell lysis. In addition, MDX-H210 elicited tumor necrosis factor-alpha secretion from monocytes when cultured in the presence of HER2/neu-positive target cells. These in vitro data suggest that targeting tumor cells to Fc gammaRI with MDX-H210 may be an effective treatment for malignancies that overexpress HER2/neu. The in vivo cytotoxic potential of MDX-H210 may be enhanced by combination therapy with the cytokines granulocyte colony-stimulating factor and IFN-gamma, which up-regulate Fc gammaRI expression on cytotoxic effector cells.
authors.affiliation: Medarex, Inc., Annandale, New Jersey 08801, USA.
authors.forename: T
authors.initials: T
authors.lastname: Keler
authors.forename: R F
authors.initials: RF
authors.lastname: Graziano
authors.forename: A
authors.initials: A
authors.lastname: Mandal
authors.forename: P K
authors.initials: PK
authors.lastname: Wallace
authors.forename: J
authors.initials: J
authors.lastname: Fisher
authors.forename: P M
authors.initials: PM
authors.lastname: Guyre
authors.forename: M W
authors.initials: MW
authors.lastname: Fanger
authors.forename: Y M
authors.initials: YM
authors.lastname: Deo
mesh_terms: D018033:Antibodies, Bispecific / Q000627:therapeutic use*; D000920:Antibody-Dependent Cell Cytotoxicity; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007167:Immunotherapy / Q000379:methods; D000090063:Proto-Oncogene Mas; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology*; D017452:Receptors, IgG / Q000276:immunology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D018033:Antibodies, Bispecific; D000090063:Proto-Oncogene Mas; D018719:Erb-b2 Receptor Tyrosine Kinases; D017452:Receptors, IgG; D014409:Tumor Necrosis Factor-alpha; C000715470:MAS1 protein, human