Current and future landscape of immune checkpoint inhibitors in urothelial cancer

Immune checkpoint inhibitors have revolutionized the fi eld of oncology, providing a novel mechanism for anticancer therapy. Programmed death 1�targeting antibodies pembrolizumab and nivolumab and programmed death ligand 1 (PD-L1)�targeting antibodies atezolizumab, durvalumab, and avelumab have been approved for use in advanced urothelial cancer in the post-platinum setting or in the upfront setting in platinum-ineligiblepatients. While this represents a signifi cant step forward inmanagement of urothelial cancers, most patients do not have anobjective response to these therapies. PD-L1 expression isnota consistently predictive biomarker, but is recommended forcheckpoint utilization in select circumstances. We report herea summary of known data and the differences between these agents, as well as future avenues to explore with immunooncologic agents in urothelial cancer. Much work is ongoing to better understand resistance mechanisms, to maximize effi cacy with combination strategies, to fi nd improved predictive biomarkers, toassess curative-intent strategies, and to better manage toxicity with these agents.