Abstract 3609: MGCD265, an orally active Met/VEGFR multitargeted kinase inhibitor in Phase II clinical development, potently inhibits clinically relevant Met mutants

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC MGCD265 is a multitargeted receptor tyrosine kinase inhibitor in Phase II clinical development, which inhibits the activation of regulators of cancer development and progression by targeting Met, the three members of the VEGFR family, Tie-2 and Ron. Met is a key player in the epithelial-mesenchymal transition (EMT) and Met deregulation is described in several types of cancer. The mechanisms involved in Met activation include co-expression of Met with its ligand HGF, overexpression of the Met protein, Met and/or HGF gene amplification or activating mutations. Originally found in hereditary papillary renal carcinoma (HPRCC), activating missense mutations in the kinase domain provided the first evidence that Met activation was causative of this disease. Mutations outside of the tyrosine kinase domain, such as those in the juxtamembrane and extracellular sema domains have also been analyzed, and found in NSCLC, SCLC, melanoma, head and neck cancer, mesothelioma and pancreatic cancer. For the clinical development of MGCD265, we demonstrated the ability of MGCD265 to inhibit clinically relevant Met mutants described in a variety of cancers, including HPRCC and NSCLC. In cell-based assays, MGCD265 inhibits the activation of Met kinase domain mutants (e.g. Y1230C) as well as mutants within the juxtamembrane region (e.g. R988C), and the extracellular domain (e.g. N375S) with nanomolar potency. This is of particular interest, as several kinase domain mutations confer resistance of Met to Met-selective agents such as PF-4217903. MGCD265 also inhibits signaling pathways activated downstream from Met mutants. The phosphorylation of Gab1 multisubstrate docking protein following the activation of Met mutants is inhibited by MGCD265 as is the ensuing activation of the Erk pathway. Furthermore, MGCD265 inhibits the motility of renal carcinoma cells expressing an extracellular domain Met mutant, and blocks tumor growth in a NSCLC cell line expressing a juxtamembrane domain Met mutant. These results, together with our previous findings, demonstrate that MGCD265 is particularly efficient at inhibiting tumor growth in animal models in which wild-type Met or Met mutants are active, suggesting that MGCD265 may particularly benefit patients with activated Met. 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 3609.