Clinicopathological correlation and prognostic value of PD-L1 expression in renal cell carcinoma

Introduction: The expression of programmed cell death-ligand 1 (PD-L1) and its correlation with the prognosis of renal cell carcinoma (RCC) remains controversial. Objectives: This study aimed to study PD-L1 expression in tumor cells and tumor-infiltrating lymphocytes (TILs) in patients with RCC and its association with clinicopathological factors and survival outcomes. Patients and Methods: PD-L1 expression in tumor cells and TILs was analyzed using immunohistochemistry (IHC) from patients with histologically proven RCC. Results: PD-L1 was positive in tumor cells for 55.8% of patients. PDL-1 expression in TIL was reported in 31.2 % of patients. Patients with PDL1 positive tumor cells had higher median tumor size (P=0.07), higher nuclear grade (P=0.56), and higher lymphovascular invasion (LVI) (P=0.23). Patients with PDL1 positive TILs were significantly associated with larger median pathological tumor size (P=0.02), higher probability of renal fat invasion (P=0.001), higher nuclear grade (P=0.05), higher probability of positive margin (P=0.02), positive LVI (P=0.03), higher pathological T stage (P=0.0004); whereas patients with PDL-1 negative TILs had earlier stage at presentation (stage I-II) (P=0.004). There was no statistically significant difference in disease-free survival (DFS), progression-free survival (PFS), or overall survival (OS) for PD-L1 expression of tumor cells and TILs. Conclusion: PDL1 positivity in TILs and not in tumor cells was significantly associated with more aggressive features, and higher stage. No association was found with DFS, PFS, or OS. These data suggest that PD-L1 expression of TILs in RCC tumors contributes to cancer aggressiveness.