Non-bacterial cystitis secondary to pembrolizumab: A case report and review of the literature.

In recent years, immune checkpoint inhibitors were successfully introduced to various of cancer therapy. Pembrolizumab, an antibody to programmed cell death-1 (PD-1), which is was approved for treatment of any adult or pediatric, unresectable or metastatic solid tumor. However, just as chemotherapeutics, immune checkpoint inhibitors have many side effects, which are named as immune-related adverse events. Common immune-related adverse events are dermatological, gastrointestinal, or endocrine side effects. However, there have been few cases that associated adverse cystitis with immune checkpoint inhibitors in recent years. We present a case showed that cystitis can be caused by pembrolizumab, which should be identified with non-bacterial cystitis.