Expression of programmed cell death-ligand 1 and its correlation with clinical outcomes in gliomas

Programmed cell death-ligand 1(PD-L1) was expressed in various malignancies, and interaction with its receptor programmed cell death 1 (PD-1) often contributed to immune evasion of tumor cells. In this study, we explored the expression of PD-L1 and its correlation with clinical outcomes in gliomas. Clinicopathological data of 229 patients with gliomas was collected. PD-L1 expression was assessed by tissue-microarray-based immunohistochemistry. Over 5% of tumor cells with cytoplasm or membrane staining was defined as PD-L1 positive expression. The associations of clinicopathological features with overall survival (OS) and disease-free survival (DFS) were analyzed by univariate analysis and multivariate analysis was further performed by Cox regression model. PD-L1 positive expression was observed in 51.1% gliomas patients and no significant association was verified between PD-L1 expression and pathological grade in 229 gliomas patients. However, PD-L1 expression rate was 49.2%, 53.7% and 68.8% for grade II, III and IV in 161 patients with those ≥ 12 months of OS, respectively. Although no significant discrepancies was displayed, there was a certain degree of differences between PD-L1 expression and pathological grade (49.2% vs. 53.7% vs. 68.8%, P = 0.327). Univariate analysis showed that PD-L1 expression was significantly associated with poor OS in the patients with long-time survival or follow up (OS ≥ 12 months) (P = 0.018), especially in patients with grade IV (P = 0.019). Multivariate analysis revealed that a strong tendency towards statistical significance was found between PD-L1 expression and poor OS (P = 0.081). In gliomas patients with long-time survival or follow up, PD-L1 positive expression could indicate the poor prognosis and it is possible that immunotherapy targeting PD-L1 pathway needed to be determined in the further study.