Abstract LB-220: Molecular predictors of sensitivity to an IGF1R inhibitor in pre-clinical models of lung and colon cancers

Abstract

Abstract Targeting the insulin like growth factor receptor (IGF1R) signaling pathway is a promising approach against a variety of cancers and several clinical trials are now underway designed to evaluate the efficacy of IGF1R inhibitors singly or in combination with chemotherapeutic agents. Identification of the optimal patient population likely to respond is critical to the success of this class of targeted agents. To identify potentially predictive biomarkers, we sought to correlate response to figitumumab (CP-751,871), a fully human monoclonal antibody against IGF1R with molecular characteristics across a panel of cell lines. Growth inhibition to CP-751,871 was assessed in a panel of non-small cell lung carcinoma (NSCLC) (n=27) and colon cancer cell lines (n=21) cultured in anchorage and anchorage-independent conditions. Mutation status, whole-genome mRNA expression and DNA copy number were correlated to drug sensitivity. In addition, RNA expression of key genes in relevant signaling pathways was also interrogated via real time PCR. In the present studies, the frequency of response was greater in colon cancer cell lines than in NSCLC. Tissue or cell origin-specific expression levels of insulin-like growth factor binding proteins (IGFBPs) were associated with sensitivity. Low IGFBP3 expression [p=0.0035] correlated with response in NSCLC cell lines whereas low IGFBP6 [p=0.013] and IGF2BP3 [p=0.038] expression correlated with response in colon cancer lines. Increased IGF1R mRNA [p=0.045] levels, microsatellite stability, and PIK3CA wild-type status were also correlated with sensitivity in colon cancer lines. In addition, high expression of erbB2 [p=0.04] and erbB3 [p=0.04] were also associated with sensitivity of colon cancer lines. Collectively, findings from these studies are of potential value to identify patient populations with increased probability of benefit from IGF1R targeted agents. Our results further indicate that molecular predictors associated with the IGF1R pathway are potentially distinct between lung and colon cancer lines and additional studies to extend to other tumor types are warranted. 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 LB-220.