Abstract 2583: LA480, a bivalent humanized c-Met monoclonal antibody, inhibits tumor growth without eliciting significant agonist activity

Abstract

Abstract The receptor tyrosine kinase c-Met and its ligand HGF elicit multiple cellular activities including cell proliferation, motility, invasion, tubulogenesis, angiogenesis and anti-apoptosis. Dysregulation of this pathway has emerged as a crucial feature for many human tumors. However, past efforts in developing c-Met therapeutic antibodies that inhibit both ligand-dependent and ligand-independent c-Met activation have been largely unsuccessful due to agonist properties of the antibodies. In fact, c-Met antibodies exhibiting medium to strong agonist activity stimulate proliferation of both normal and tumor cells. We report here that LA480, a bivalent humanized monoclonal c-Met antibody, blocks HGF binding to c-Met and also induces c-Met internalization. Moreover, LA480 inhibits growth of xenograft tumors mediated by HGF-dependent and HGF-independent c-Met pathway activation. In order to evaluate whether LA480 has agonist activity, we tested LA480 in the following HGF-responsive biological assays: proliferation of primary human hepatocytes and tumor cell lines, scattering of DU145 cells, stimulation of HepG2 invasion and tubulogenesis, tube formation in endothelial and stromal cell co-cultures, and protection from apoptosis induced by staurospor in Caki-1 cells. A bivalent c-Met agonist antibody and HGF were included in the assays as positive controls, in addition to antibody isotype negative controls. Our results demonstrate that LA480 does not significantly stimulate cell proliferation, scattering, invasion, tubulogenesis, angiogenesis or apoptosis protection in the above assay systems. Under the same conditions, the agonist positive control c-Met antibody and HGF both significantly induced these biological effects. These unique properties of LA480 suggest that it may be a promising therapeutic reagent for treatment of cancers driven by ligand-dependent and ligand-independent c-Met activation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2583.