Fibroblast growth factor receptor 1 (FGFR1) and SRY-related HMG-box (SOX2) amplification in squamous cell carcinoma (SCC) of the lung.

Abstract

11025 Background: SOX2 is a key transcription factor that is amplified in lung SCC. FGFR1 is a receptor tyrosine kinase that promotes cell proliferation, survival and apoptotic resistance through the PLCγ/PKC, RAS/MAPK and PI3K-AKT pathways, respectively. FGFR1 is amplified in 15-25% of lung SCC. Pre-clinical studies of targeted inhibitors showed a growth dependency on FGFR1 amplification both in vitro and in vivo. A European, multicenter clinical trial of second-line treatment with BIBF1120, an FGFR1 inhibitor, will be performed in p with lung SCC with FGFR1 amplification. Methods: We have examined FGFR1 and SOX2 gene copy number (GCN) in 76 lung SCC p by multiplex ligation-dependent probe amplification (MLPA). Genomic DNA (gDNA) was isolated from enriched tumor cells by laser capture microdissection from formalin-fixed paraffin embedded (FFPE) tumor tissue. 50-100 ng of gDNA was analyzed in each of three independent replicates per tumor sample. Two independent probe sets were used for each gene analyzed. For inter-patient GCN comparisons, the results from each patient were normalized against the GCN values derived from FFPE peripheral blood leukocytes. In order to study intra-tumor heterogeneity (TH), we examined FGFR1 and SOX2 GCN in different areas of 4 tumors. In 2 p, TH was examined in serial tumor biopsies and/or resections obtained at different points of disease progression. Results: High FGFR1 amplification was detected in 13/76 (17.10%) and low amplification in 7/76 (9.21%) p. High SOX2 amplification was observed in 38/63 (60.32%) and low amplification in 9/63 (14.28%) p. 46.15% of the FGFR1-amplified tumors were also co-amplified for SOX2. Intra-TH was observed in 2/4 tumors. Survival according to FGFR1 and SOX2 GCN will be presented. In addition, GCN changes in FGFR1, SOX2, PIK3CA, PDGFRA, KDR, EGFR and MET over 10 years of follow-up will be presented for one surgically resected SCC lung p. Conclusions: FGFR1 and SOX2 co-amplification could represent a novel therapeutic target and warrants further research.