Prognostic impact of PD-L1 expression in correlation with HLA class I expression status in stage I adenocarcinoma of the lung.

Abstract

8548 Background: Programmed death-ligand 1 (PD-L1) and human leukocyte antigen (HLA) class-I, expressed on tumor cells (TCs), are important regulators in cancer immunity. The current study was conducted to assess prognostic impact of PD-L1 status in correlation with HLA class-I status in lung adenocarcinoma. Methods: A total of 94 patients with completely resected pathologic stage I lung adenocarcinoma were retrospectively reviewed. PD-L1 expression on TCs was evaluated with immunohistochemistry, in correlation with several clinicopathological and molecular features including HLA class-I expression on tumor TCs. Results: Seventeen patients (18.1%) had tumor with positive PD-L1 expression (percentage of TCs expressing PD-L1, ≥ 5%), and the incidence was higher in smokers with higher smoking index and in poorly differentiated tumor. There was no significant correlation between HLA class-I expression and PD-L1 expression. PD-L1-positivity was a significant factor to predict a poor survival (5-year survival rate, 66.7% versus 85.9%; P = 0.048), which was enhanced in tumor with normal HLA class-I expression (p = 0.029) but disappeared in tumor with reduced HLA class-I expression. Conclusions: The prognostic impact of PD-L1 expression on TCs in early-stage resectable lung adenocarcinoma was distinct according to HLA class-I expression on TCs.