Clinical experience with pembrolizumab in the treatment of advanced urothelial cancer

[Introduction and objective) Pembrolizumab, a programmed death one checkpoint inhibitor, was approved as second-line treatment of advanced urothelial cancer (UC). We performed a pilot study to investigate the effect of pembrolizumab. [Methods and patients) 19 patients who were treated with pembrolizumab from April 2018 to July 2019 were retrospectively reviewed and analyzed to evaluate efficacy and safety. Pembrolizumab was administered after platinum-based chemotherapy. [Results) The median age was 68 years old; male-to-female ratio was 14:5; primary lesions were upper urinary tract, bladder and others (10, 7 and 2, respectively); recurrence lesions were lymph nodes, lung, bone and liver (14, 9, 4 and 2, respectively). The median number of cycles was three courses (range, 1-16). The objective response rate, median progression-free survival period (PFS), and median overall survival period (OS) were 24%, 2.7 months and 9.1 months, respectively. Pembrolizumab showed a long-term effect for all responsive cases until the end of the follow-up period. Immune-related adverse events (irAE) were observed in four patients. Neutrophil-to-lymphocyte ratio was negatively correlated with PFS, but not significantly correlated with OS. [Conclusion) Pembrolizumab demonstrated a comparable efficacy and safety profile in the treatment of advanced UC. In particular, responsive cases showed a durable response. Further investigation is required to identify predictive markers that can be routinely used in clinical practice.