High PD-L1 expression on immune cells, but not on tumor cells, is a favorable prognostic factor in urothelial carcinoma

Aims: To explore the prognostic value of high PD-L1 expression on tumor cells (TC) and tumor-infiltrating immune cells (TIIC) in urothelial carcinoma (UC). Patients & methods: 162 UC specimens were evaluated for PD-L1 expression on TIIC and TC with the SP263 assay. High PD-L1 expression was defined as ≥25% staining. Results: High PD-L1 expression on TC in UC patients with stage T1-4 disease was associated with poor overall survival. However, high PD-L1 expression on TIIC in UC patients with stage T1-4 disease revealed favorable disease-free and overall survival; more significant differences were observed in patients with stages T2-4. Multivariate analysis revealed that high PD-L1 expression on TIIC was an independent prognostic predictor for better disease-free and overall survival. Conclusion: High PD-L1 expression on TIIC, but not on TC, is a favorable prognostic factor in UC.Lay abstract Bladder cancer is the tenth most common form of cancer worldwide, and urothelial carcinoma is the most common type of bladder cancer. PD-L1 is a protein that can be expressed on the surface of many tissue types, including tumor cells (TC) and tumor-infiltrating immune cells (TIIC). PD-L1 can help the tumor evade the body’s natural immune defense system. The expression of PD-L1 not only related to the response of immunotherapy but is also associated with the prognosis in bladder cancer. However, the prognostic significance of PD-L1 expression on TC and TIIC remains controversial. This study drew a conclusion that high PD-L1 expression on TIIC, but not on TC, is a favorable prognostic factor in urothelial carcinoma.