Programmed cell death‐ligand 1 (PD‐L1) expression and fibroblast growth factor receptor 1 (FGFR1) amplification in stage III/IV lung squamous cell carcinoma (SQC)

BACKGROUND This study was conducted to explore programmed cell death-ligand-1 (PD-L1) expression and fibroblast growth factor receptor 1 (FGFR1) amplification in stage IIIB/IV lung squamous cell carcinoma (SQC). Correlations between PD-L1 and FGFR1, and with clinicopathological characteristics, efficacy of platinum-based chemotherapy, and prognosis were analyzed. METHODS One hundred and twenty-eight consecutive stage III/IV SQC patients were enrolled in this study from 2009 to 2014. Seventy-eight patients received platinum-based chemotherapy. Immunohistochemistry was used to assess PD-L1 expression and fluorescence in situ hybridization was applied to detect FGFR1 amplification. RESULTS PD-L1 expression was detected in 61.7% (79/128) of lung SQC patients. Smokers had significantly higher PD-L1 expression rates than non-smokers (66.1% vs. 44.0%, P  = 0.042, respectively). The objective response and disease control rates for platinum-based chemotherapy were not significantly different between PD-L1 negative and positive patients (43.3% vs. 36.2%, P  = 0.434; 80.0% vs. 78.7% P  = 0.840, respectively); however, overall survival in PD-L1-negative patients was significantly longer than in PD-L1-positive patients (41.5 vs. 19.3 months, P  = 0.001). Twenty-five percent (32/128) of patients displayed FGFR1 amplification, with a lower rate in stage III patients compared to stage IV (17.1% vs. 36.5%, P  = 0.013, respectively). There was no significant difference in FGFR1 amplification levels between overall response, disease control or overall survival rates. No correlation was observed between PD-L1 expression and FGFR1 amplification ( P  = 0.916). CONCLUSION PD-L1 expression may function as a prognostic factor in Chinese stage III/IV SQC patients. FGFR1 amplification is more prevalent in late stage SQC patients but does not predict chemotherapy response. There is no apparent correlation between PD-L1 expression and FGFR1 amplification.