Prognostic value of PD-L1 expression for surgically treated localized renal cell carcinoma: implications for risk stratification and adjuvant therapies

Background: We aimed to evaluate the prognostic role of programmed-death receptor ligand (PD-L1) in a multinational cohort of patients with localized renal cell carcinoma (RCC). Methods: Formalin-fixed paraffin-embedded blocks of 1017 patients from the Latin American Renal Cancer Group were analyzed. Tissue microarrays were immunostained for PD-L1 using a commercially available monoclonal antibody. Expression of PD-L1 in > 5% tumor cells was considered positive. PD-1 expression in immune cells was also assessed. All cases were reviewed twice based on antibody expression and compared with a positive control. Cox proportional hazard regression models were used to identify predictors of recurrence-free survival (RFS) and overall survival (OS). Results: A total of 738 cases with complete follow up met criteria. Median age was 57 [interquartile range (IQR): 49-64] years, and median follow up was 34 (IQR: 15-62.9) months. Median tumor size was 5 cm (IQR: 3.0-7.5 cm). Approximately 8.2% and 7.6% of tumors were PD-L1 and programmed cell-death 1 (PD-1) positive, respectively. PD-L1 and PD-1 positivity were significantly associated with higher tumor stage (both p < 0.001), and presence of tumor necrosis and lymphovascular multivariable analyses; PD-L1 positivity was found as a predictor of worse RFS [hazard ratio (HR) = 2.08, p = 0.05] and OS (HR = 2.61, p = 0.02). Conclusions: PD-L1 positivity was significantly associated with worse outcomes for patients with localized RCC at intermediate follow up. This marker may help stratify patients for stricter surveillance after surgical treatment and provide a basis for checkpoint-inhibitor therapy in the adjuvant setting.