Background: Antibodies against programmed death 1 (PD-1) and programmed death ligand 1 (PD-L1) have recently demonstrated a survival benefit in several types of cancer, including melanoma and non-small cell lung cancer (NSCLC). PD-L1 expression has provided a predictive biomarker for anti-PD-1/PD-L1 therapy. However, the relationship between PD-L1 expression and clinical and clinicopathological characteristics remains unclear in NSCLCs. The aim of this study was to investigate the relevance of PD-L1 expression to clinical and clinicopathological factors in resected NSCLCs. Materials and Methods: PD-L1 expression was evaluated in 154 surgically resected NSCLC specimens by immunohistochemistry (IHC) using the SP142 antibody. Before the IHC of clinical samples, we performed a concordance study of Western blot analysis and IHC in 17 lung cancer cell lines. We evaluated the relationship between PD-L1 expression and clinical and clinicopathological factors by univariate and multivariate analyses. Survival curves were estimated by the Kaplan-Meier methods, and differences in survival distributions were evaluated by the log-rank test.

Results: PD-L1 expression was well concordantly observed in Western blot analysis and IHC in the lung cancer cell lines analyzed. PD-L1 expression was observed in 51 of 154 (33%) surgically resected NSCLCs. PD-L1 expression was significantly correlated with male, heavy smoking history, squamous cell carcinoma, and moderate/poor differentiation of tumors by univariate analysis. In multivariate analysis, tumor differentiation had a strong relationship with PD-L1 expression (odds ratio: 6.32, 95% CI: 1.70-23.49, P = 0.006). The survival was not statistically different between patients with high and low PD-L1 expression (5-year survival rate: 44.1% versus 58.1%, P = 0.22). PD-L1 expression was not an independent prognostic factor in univariate and multivariate analyses.

Conclusion: PD-L1 expression was strongly associated with tumor differentiation in resected NSCLCs. PD-L1 expression was not a prognostic factor in this cohort of resected NSCLCs.

Citation Format: Yoshihito Ohhara, Ichiro Kinoshita, Utano Tomaru, Kanako C. Hatanaka, Yutaka Hatanaka, Rio Honma, Satoshi Takeuchi, Yasushi Shimizu, Kichizo Kaga, Yoshihiro Matsuno, Hirotoshi Dosaka-Akita. Clinicopathological features of programmed cell death ligand 1 (PD-L1) expression in resected non-small cell lung cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2625. doi:10.1158/1538-7445.AM2017-2625

©2017 American Association for Cancer Research.
2017
American Association for Cancer Research.