SOX2 and FGFR1 gene copy number in surgically resected non-small cell lung cancer (NSCLC).

7061 Background: SOX2 is a member of the SRY-related HMG-box family of transcription factors and has been shown to be frequently amplified and overexpressed in squamous cell lung cancer, with conflicting results regarding its prognostic relevance. Similarly, FGFR1, a transmembrane tyrosine kinase receptor belonging to the fibroblast growth factor receptor family, has been recently reported to be amplified in squamous cell lung carcinomas, suggesting a potential role for FGFR1 as a therapeutic target in NSCLC. Aim of the present study is to evaluate SOX2 and FGFR1 gene copy number in surgically resected NSCLCs, to investigate their prognostic relevance and their association with clinico-pathological characteristics. Methods: SOX2 and FGFR1 gene copy number was assessed by fluorescence in situ hybridization (FISH) in tissue microarray cores from 447 surgically resected NSCLCs. Each patient was given a score ranging from 1 to 6 according to increasing mean copy number per cell of each gene, with 6 indicating true gene amplification. Results: SOX2 and FGFR1 FISH was successfully performed in 445 patients (pts), which were grouped as + (score 5-6) and - (score 1-4). Using this scoring system 105 (23.6%) pts tested SOX2+, while 74 (16.6%) pts resulted FGFR1+. True gene amplification for SOX2 and FGFR1 was observed in 19 (4.3%) and 37 (8.3%) cases, respectively. SOX2+ and FGFR1+ status was significantly associated with squamous histology (p<.001). Additionally, SOX2+ pts had a significantly higher chance of being former/current smokers, male and FGFR1+. FGFR1 gene status had no prognostic impact in the whole population and in the squamous cell carcinoma subgroup. Conversely, SOX2+ pts had significantly longer overall survival compared with SOX2- pts (HR 0.68, p=.020). When restricting survival analysis to squamous cell histology, stage I-II SOX2+ pts had a significant survival advantage compared with SOX2- group (HR 0.38, p=.006), while no difference was observed in stage III-IV pts. Conclusions: Increased SOX2 and FGFR1 gene copy number is a common event in lung cancer pts with squamous cell histology. SOX2 gene gain is a favorable prognostic factor in surgically resected pts, particularly in early stage squamous cell cancers.