Advancements in the understanding of tumor immunology in urothelial carcinoma (UC) have led to U.S Food and Drug Administration (FDA) approval of five novel anti-programmed cell death protein-1/ligand 1 (PD-1/L1) checkpoint inhibitors. In 2017, the anti-PD-L1 antibody atezolizumab and the anti-PD-1 antibody pembrolizumab gained approval for use in cisplatin-ineligible patients with locally advanced and metastatic UC. These approvals were based on single-arm trials, IMvigor210 (atezolizumab) and KEYNOTE-052 (pembrolizumab). Since then, additional checkpoint inhibitors, including avelumab, durvalumab, and nivolumab, have gained approval. Preliminary results suggest additional benefits with combinations of these agents in both first- and subsequent-line therapies, inferring a paradigm shift in the future treatment approach in advanced UC. Ongoing clinical trials will investigate how to utilize predictive biomarkers for optimal patient selection and to incorporate immunotherapy into earlier lines of multimodal treatment. In this comprehensive review, we summarize the evidence supporting the use of checkpoint inhibitors for patients with UC, and highlight ongoing clinical trials that are investigating novel combinations of immunotherapy in various disease settings.
Keywords: biomarkers; clinical trials; immune checkpoint inhibitor; immunotherapy; urothelial carcinoma.