PD-L1 expression in tumor-infiltrating lymphocytes (TILs) as an independent predictor of prognosis in patients with pN0 bladder cancer undergoing radical cystectomy.

OBJECTIVES:Checkpoint inhibitors have led to a paradigm shift in urothelial carcinoma (UC) treatment. However, the relationship between PD-L1 expression status and oncological outcomes in UC patients remains uncertain. Here, we investigated the prognostic value of PD-L1 expression status in patients with UC of the bladder (UCB) who underwent radical cystectomy (RC). MATERIALS AND METHODS:We retrospectively analyzed pathological specimens from 97 UCB patients treated with RC from 1990 to 2015 at Kitasato University Hospital. Immunohistochemical staining using SP263 was performed to evaluate PD-L1 expression in tumor cells (TCs) and tumor-infiltrating lymphocytes (TILs). Kaplan-Meier plots and proportional Cox hazard ratios were examined to assess the relationship between PD-L1 expression and clinicopathological parameters and survival outcomes. RESULTS:Of the 97 specimens, 19.5% contained PD-L1-positive TCs, and 35.0% contained PD-L1-positive TILs. Regarding clinicopathological factors, PD-L1-positive TCs and TILs were significantly associated with high-grade tumors (TCs, P = 0.01; TILs, P = 0.003). Kaplan-Meier analyses showed that PD-L1-positive TCs were not correlated with survival rates. However, PD-L1-positive TILs were significantly associated with better recurrence-free survival (RFS; P = 0.03) and better cancer-specific survival (CSS; P = 0.02). Univariate analysis, but not multivariate analysis, CSS indicated that PD-L1-positive TILs were significant predictors of patient prognoses. Multivariate analysis showed that PD-L1-positive TILs independently predicted CSS in patients without lymph node metastasis (pN0). CONCLUSION:Positive PD-L1 expression is associated with high-grade tumors. PD-L1-positive TILs are independent predictors of favorable survival outcomes in surgically resected UCB patients at stage pN0.