Effectiveness and safety profile of pembrolizumab for metastatic urothelial cancer: A retrospective single‐center analysis in Japan

BACKGROUND: The paradigm of medical treatment for metastatic urothelial carcinoma is dramatically changing through the introduction of pembrolizumab. AIM: We investigated the treatment effectiveness, the safety profile, and the prognostic factors of pembrolizumab in Japanese real‐world clinical practice. METHODS AND RESULTS: The medical records of 74 consecutive Japanese patients with metastatic urothelial cancer (UC), who started pembrolizumab as a second‐ or later‐line treatment at our institution between January 2018 and March 2020, were reviewed and statistically analyzed. The median follow‐up period after initiation of pembrolizumab was 8.5 (interquartile range: 3.5–15.7) months. The objective response rate was 30.2%, the median progression‐free survival period was 4.9 months, and the median overall survival (OS) period was 13.3 months. Evaluation revealed that 39 (52.9%) patients experienced adverse events (AEs), among whom eight patients (10.9%) had severe AEs (grade 3 or more), including grade 5 hemophagocytic syndrome. Multivariate analysis indicated that the presence of liver metastasis, worse performance status (≥2), elevated serum lactate dehydrogenase, and increased C‐reactive protein were predictive of shorter OS. CONCLUSION: We studied the effectiveness and safety profile of pembrolizumab therapy in Japanese UC patients. We believe that the data presented here will be useful for clinical physicians.