Objective: Programmed death-ligand 1 (PD-L1) is known to be over-expressed in non-small cell lung cancer (NSCLC). However, the impact of chemotherapy on the altered status of PD-L1 expression has not been examined for NSCLC. The present study was intended to examine the impact of neoadjuvant chemotherapy on PD-L1 expression and its prognostic significance in lung squamous cell carcinoma (SCC).
Patients and methods: Matched tumor samples were obtained from 76 SCC patients prior to and after neoadjuvant chemotherapy. The expression of PD-L1 was evaluated by immunohistochemistry. Survival analysis was performed by the Kaplan-Meier method.
Results: Prior to neoadjuvant chemotherapy, PD-L1 expression was identified in 52.6% (40/76) of SCC patients while 61.8% (47/76) were positive for PD-L1 expression after neoadjuvant chemotherapy. Nine patients switched from negative to positive while another two patients' samples showed the reverse of the above result. Multivariate analysis demonstrated that postoperative expression of PD-L1 was an independent prognostic factor for overall survival (HR=0.50, P=0.003), but not for PD-L1 expression prior to neoadjuvant chemotherapy.
Conclusion: Neoadjuvant chemotherapy may up-regulate the expression of PD-L1. As compared with the status of PD-L1 expression prior to chemotherapy, the postoperative expression of PD-L1 is a better prognostic factor for overall survival in SCC.
Keywords: Chemotherapy; Overexpression; Programmed death-ligand 1; SCC; Squamous cell carcinoma; Survival; squamous cell carcinoma.
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