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.