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

Abstract

ObjectivesCheckpoint 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 methodsWe 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. ResultsOf 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). ConclusionPositive 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.