Abstract 558: Correlations of FGFR1 with ligand signaling in small-cell lung cancer

Abstract

Abstract Introduction: Small cell lung cancer (SCLC) accounts for 15% of all lung cancers and has been under-studied relative to novel therapies. Signaling through fibroblast growth factors (FGF2, FGF9) and their high-affinity receptor (FGFR1) has recently emerged as a contributing factor in the pathogenesis and progression of non-small cell lung cancer (NSCLC). However, knowledge of FGFR1 and ligand expression in SCLC is limited. Methods: FGFR1 gene copy number, mRNA levels and protein expression were determined by silver in situ hybridization (SISH), mRNA ISH and immunohistochemistry (IHC) in primary tumors from 78 SCLC patients. Expression of the ligands FGF2 and FGF9 mRNA and protein were determined by mRNA ISH and IHC, respectively. Spearman's correlations were conducted using SAS 9.4. Results: FGFR1 protein expression by IHC demonstrated a significant correlation with FGFR1 gene copy number (p = 0.03) and FGFR1 mRNA levels (p<0.0001). The positivity of FGFR1 mRNA in the SCLC cohort was 21%. FGFR1 mRNA expression correlated with both FGF2 (p = 0.0001) and FGF9 (p = 0.0018) mRNA levels, as well as with FGF2 (0.0105) and FGF9 (0.0012) protein levels. There was no significant association between FGFR1 and ligands with clinical characteristics or prognosis. Conclusions: FGFR1 amplification and mRNA levels correlate with FGFR1 protein expression. The SCLC cohort has a substantially higher proportion of FGFR1 mRNA positive cases (21%) compared to FGFR1 gene copy number positive cases (7.8%). Combined analysis of FGFR1 and ligand expression may be valuable to determine which SCLC patients may respond to FGFR1 inhibitor therapy. Key Words: small cell lung cancer; FGFR1; FGF2; FGF9 Citation Format: Hui Yu, Andrzej Badzio, Theresa Boyle, Xian Lu, Christopher J. Rivard, Ashley Kowalewski, Brad Rikke, Kim Ellison, Leslie Rozeboom, Biftu Hassan, Fred R. Hirsch. Correlations of FGFR1 with ligand signaling in small-cell lung cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 558. doi:10.1158/1538-7445.AM2015-558