Programmed Cell Death Ligand 1 Expression in Primary Central Nervous System Lymphomas: A Clinicopathological Study

Abstract

Background/aim: Programmed cell death ligand 1 (PD-L1)/programmed cell death 1 (PD-1) have been shown to predict response to PD-L1/PD-1-targeted therapy. We analyzed PD-L1 expression in primary central nervous system lymphomas (PCNSLs).

Materials and methods: PD-L1 protein and mRNA expression were evaluated in 64 PCNSL tissue samples. IFN-γ, IL-10, CD4, and CD8 mRNA expression was also evaluated.

Results: PD-L1 protein was detected in tumor cells in 2 (4.1%) cases and in tumor microenvironments in 25 (52%) cases. PD-L1 mRNA positively correlated with IFN-γ (p=0.0024) and CD4 (p=0.0005) mRNA expression. IFN-γ mRNA positively correlated with CD8 mRNA expression (p=0.0001). Furthermore, tumor cell PD-L1 expression correlated positively with overall survival (p=0.0177), whereas microenvironmental PD-L1 expression exhibited an insignificant negative trend with overall survival (p=0.188).

Conclusion: PD-L1 was expressed on both tumor and/or tumor-infiltrating immune cells in PCNSL. The biological roles of this marker warrant further investigation.

Keywords: PD-L1; Primary central nervous system lymphoma; checkpoint inhibitor; diffuse large B cell lymphoma; tumor microenvironment; tumor-infiltrating immune cell.