Bispecific HER2 x CD3 antibodies enhance T-cell cytotoxicity in vitro and localize to HER2-overexpressing xenografts in nude mice.
Recently, we reported the development of fully humanized bispecific F(ab')2 antibodies with dual binding specificities to human T-lymphocytes and to tumor cells overexpressing HER2. These antibodies were shown to effectively mediate targeted HER2-overexpressing tumor cell killing by freshly isolated human T-cells. In this report we extend our studies to describe the interaction of the bispecific antibody with activated T-lymphocytes (ATL) maintained in culture for an extended period of time. A microtiter plate radioreceptor assay was used to elucidate the affinity of bispecific antibody binding to ATL. The data show that ATL maintained in vitro for up to 5 weeks continued to express high-affinity CD3 surface markers that bound to bispecific antibody with a Kd of 2.49 nM and exerted cytolytic activities against targets overexpressing HER2. In addition, we demonstrated the specific localization of HER2 x CD3 bispecific antibody to HER2-overexpressing tumor xenografts in nude mice. Furthermore, HER2 x CD3 bispecific antibody has the ability to inhibit the proliferative activities of breast tumor (SKBR-3) cells in vitro. The clinical implications of these data are discussed.
Shalaby
M R
MR
Department of BioAnalytical Technology, Genentech, Inc., South San Francisco, California 94080-4990.
Carter
P
P
Maneval
D
D
Giltinan
D
D
Kotts
C
C
D000818:Animals; D018033:Antibodies, Bispecific / Q000276:immunology*; D001667:Binding, Competitive; D017252:CD3 Complex / Q000276:immunology*; D002455:Cell Division / Q000276:immunology; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D005434:Flow Cytometry; D018734:Genes, erbB-2; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation / Q000276:immunology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014183:Transplantation, Heterologous / Q000276:immunology; D014407:Tumor Cells, Cultured
D018033:Antibodies, Bispecific; D017252:CD3 Complex; D007140:Immunoglobulin Fab Fragments; D018719:Erb-b2 Receptor Tyrosine Kinases