Background: Programmed death-ligand 1 (PD-L1) positivity is associated with poor prognosis in renal cell carcinoma (RCC). Because the prognostic impact and effect of confounding factors are less known, we investigated the prognostic significance of PD-L1 expression in Japanese patients with recurrent/metastatic RCC who started systemic therapy in 2010–2015. Methods: This multicenter, retrospective study recruited patients from 29 Japanese study sites who had prior systemic therapy for RCC (November 2018 to April 2019) and stored formalin-fixed paraffin-embedded primary lesion samples. The primary outcome was overall survival (OS) by PD-L1 expression. Secondary outcomes included OS in subgroups and duration of first- and second-line therapies by PD-L1 expression. OS distributions were estimated using Kaplan–Meier methodology. Results: PD-L1 expression (on immune cells [IC] ≥ 1%) was observed in 315/770 (40.9%) patients. PD-L1 positivity was more prevalent in patients with poor risk per both Memorial Sloan Kettering Cancer Center [MSKCC] and International Metastatic RCC Database Consortium, and high-risk pathological features (higher clinical stage, nuclear grade and sarcomatoid features). Median OS for PD-L1–positive patients was 30.9 months (95% CI 25.5–35.7) versus 37.5 months (95% CI 34.0–42.6) for PD-L1–negative patients (HR 1.04 [90% CI 0.89–1.22, p = 0.65]; stratified by MSKCC risk and liver metastases). Propensity score weight (PSW)-adjusted OS was similar between PD-L1–positive and –negative patients (median 34.4 versus 31.5 months; estimated PSW-adjusted HR 0.986). Conclusions: This study suggests PD-L1 status was not an independent prognostic factor in recurrent/metastatic RCC during the study period because PD-L1 positivity was associated with poor prognostic factors, especially MSKCC risk status.
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