Abstract PO-042: FGFR1 expression correlates inversely with the in vitro and in vivo efficacy of FGFR inhibitors in pancreatic cancer

Abstract

Abstract Aberrant functions of fibroblast growth factor receptors (FGFR) have been implicated in the tumor progression of pancreatic cancer (PaCA). However, the mechanisms of FGFR action and the therapeutic utilities of FGFR inhibitors (FGFRi) in PaCA remain largely under-investigated. Here the mechanisms of FGFR inhibition in PaCA were investigated using pan-FGFRi that are under clinical development and specific shRNA against individual FGFRs. FGFRi treatment, such as BGJ398 and AZD4547, significantly inhibited cell proliferation, migration, and invasion, and cell expression of key markers associated with cell survival and invasiveness was suppressed, in multiple PaCA cell lines. Gemcitabine (Gem) is the standard-of-care for PaCA, and the development of Gem resistance (GemR) compromises its efficacy, thereby Gem only provides modest survival benefits. We found that FGFRi was effective in inhibiting cell proliferation, migration of strongly GemR cells and tumors (named as MIA-GR8 cells and MIA-GR8 tumors) that were all derived by increasing Gem exposure from MIA PaCa-2 cells in vitro and selected by Gem in vivo. These results suggest its potential clinical utility as a class of alternative drug candidates in tumors that acquired GemR. Downregulation of GemR markers mediated by FGFRi treatment in GemR cells also suggested its therapeutic application of FGFRi in combination with Gem, in order to overcome GemR. Mechanistically, the molecular mechanisms of individual FGFR were investigated. shRNA-mediated inhibition of FGFR2 or FGFR3 did not decrease cell growth, and the overexpression of FGFR1 promoted cell migration rather than proliferation. Furthermore, the efficacy of FGFRi treatment was investigated in multiple cell lines and patient-derived xenograft. The inhibitory effects of BGJ398 in PANC-1 cell growth and migration were compromised by exogenic overexpression of FGFR1, and its efficacy on cell viability suppression was correlated with FGFR1 in multiple cell lines. In patient-derived xenografts, the efficacy of FGFRi on tumor growth inhibition was also correlated with FGFR1 expression. These data provide evidence that precision medicine which targets FGFR using FGFRi in PaCA tumors which express relatively modest or low amount of FGFR1 could be more effective than that with a high FGFR1 expression. Citation Format: Qingxiang Lin, Andrea Serratore, Eugene Kandel, Robert M. Straubinger. FGFR1 expression correlates inversely with the in vitro and in vivo efficacy of FGFR inhibitors in pancreatic cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PO-042.