Association of PD-L1 and PD-1 Expression With Clinicopathological Characteristics and Prognosis in Upper Tract Urothelial Carcinoma.

[INTRODUCTION] To investigate the expression of PD-L1/PD-1 in tumor cells and tumor-infiltrating immune cells (TIICs) and their association with clinicopathologic characteristics and prognosis in UTUC.

[PATIENTS AND METHODS] Immunohistochemistry (IHC) was performed to detect the expression of PD-L1 and PD-1 in 124 formalin-fixed paraffin embedded tumor specimens in UTUC. Clinicopathological variables and overall survival (OS) were documented. Association between PD-L1, PD1 with clinicopathologic characteristics and OS were evaluated using binary logistic regression or Cox regression. Statistical significance was considered at 0.05.

[RESULTS] Of 113 eligible patients (11 excluded due to insufficient tissue), 31.9% (36/113) showed PD-L1⁺ tumor cells, and 28.8% (29/101) had PD-L1⁺ TIICs. PD-1⁺ TIICs were observed in 58.4% (59/101). PD-L1 expression in tumor cells correlated significantly with high tumor grade (P = .029). PD-L1⁺ tumor cells predicted reduced OS in univariate (HR = 1.83, P = .025) and multivariable analyses (HR = 2.15, P = .007). PD-1⁺ TIICs associated with early-stage disease (P = .005) but not OS (P = .166). PD-L1⁺ TIICs also showed no OS association (P = .644).

[CONCLUSIONS] PD-L1 is expressed in 31.9% of UTUC tumors and 28.8% of TIICs, while PD-1 is detected in 58.4% of TIICs. Tumor cell PD-L1 positivity independently predicts poor survival and may drive UTUC progression. PD-1⁺ TIICs correlate with early-stage disease but lack prognostic value for OS. These findings highlight PD-L1 as a potential biomarker for risk stratification in UTUC.