Abstract LB-329: Identification of alternative mechanisms of resistance to FGFR inhibitor treatment in FGFR1-amplified large cell compared to FGFR1-amplified small cell lung cancer models

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA It is becoming increasingly clear that many solid tumors are not a homogeneous mass, but instead consist of highly heterogeneous microsystems comprised of multiple tumor subpopulations together with stromal cells. Such heterogeneity is often attributed to genetic and epigenetic alterations that promote functional specialization of different tumor subpopulations, thereby supporting the growth and differentiation of the primary tumor and subsequent invasion and metastases. This intratumoral complexity serves as a base for a range of intrinsic and acquired resistance mechanisms that are responsible for the failure of targeted therapies, especially in highly heterogeneous tumors such as lung cancer. JNJ-42756493 is a nanomolar inhibitor of fibroblast growth factor receptors (FGFRs) 1, 2, 3 and 4, that is currently being evaluated in Phase I clinical trials. As part of our ongoing preclinical program to elucidate potential mechanisms of resistance to JNJ-42756493, we have developed and characterized a range of cell-based models, representing different solid tumor histologies which show resistance to JNJ-42756493 and other FGFR inhibitors. Here, we describe the outgrowth of pre-existing subpopulations of cells that were intrinsically resistant to FGFR inhibition, from different FGFR1-amplified lung cancer subtypes: NCI-H1581, large cell (LCLC), and DMS114, small cell lung carcinoma (SCLC) cells. Following expansion of these resistant clones, a range of comparative ‘omics’ approaches (microarray analysis, RNA sequencing, shRNA knockdown screening, exome sequencing, and phospho RTK array analysis) were employed to explore the molecular mechanisms of resistance. Comprehensive profiling of these intrinsically resistant subpopulations has revealed that the LCLC and SCLC models have divergent mechanisms of resistance. Met pathway activation was found in LCLC model whilst IGF1R was found to be activated in the SCLC model resistant to FGFR inhibition. This is a novel observation of IGF1R pathway activation in FGFR1 amplified small cell lung cancer models that are resistant to FGFR inhibition. Blocking Met or IGF1R pathways with targeted therapies was observed to prevent the emergence of intrinsic resistance observed in these FGFR driven tumors. Follow-up experiments were performed in vitro and in vivo to confirm these intrinsic mechanisms of resistance and these data help build a rationale for combinations of targeted therapies in the clinic. Finally, our data indicates that pre-existing heterogeneity is likely to be a key driver for the appearance of resistance to targeted therapy in independent lung cancer models. Citation Format: Eleonora Jovcheva, Souichi Ogata, Kelly Van De Ven, Caroline Paulussen, Inez Van de Weyer, Hans De Wolf, Hugo Ceulemans, Steve McClue, Jorge Vialard, Timothy Perera. Identification of alternative mechanisms of resistance to FGFR inhibitor treatment in FGFR1-amplified large cell compared to FGFR1-amplified small cell lung cancer models. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-329. doi:10.1158/1538-7445.AM2014-LB-329