The usage of Pembrolizumab in Metastatic Urothelial Carcinoma

Bladder cancer is common cancer threatening countless people’s lives. Urothelial carcinoma contributes to 90% of bladder cancer cases and has a low average five-year relative survival rate of 6% if metastasized. Finding appropriate therapy for those with metastatic urothelial carcinoma (MUC) is therefore crucial. Most patients cannot get first-line cisplatin-based chemotherapy, and a small number cannot receive any platinum-based treatment. The immune checkpoint inhibitor pembrolizumab blocking the PD-1 with the PD-L1 protein expressed on urothelial carcinoma cells. This blockade reduces immunosuppressive effects and restores effective neoplastic cell eradication. Compared to conventional chemotherapy strategies, pembrolizumab had significant improvement in the safety profile, reduction of adverse effect rate, and elongation of survival under certain conditions. It offers an alternative treatment option for those who are ineligible for chemotherapy. Pembrolizumab has been given the approval to be used in first-line settings for patients who are ineligible for platinum and second-line settings for patients who have already had chemotherapy. This paper summarizes the mechanism and application of pembrolizumab for treating MUC. The drug’s efficacies under different conditions, advantages, current issues, and future investigation directions are discussed.