Immunotherapy has revolutionized cancer care in the modern era of oncology. Research in immunotherapy has led to important advances in the treatment of melanoma, non-small cell lung cancer and other malignancies using checkpoint inhibition. Multiple systemic immunotherapies have been approved or are currently being investigated for the management of urothelial malignancies (1). Five antibodies targeting the programmed cell death protein 1--programmed cell death 1 ligand 1 (PD-1--PD-L1) pathway have been approved by the U.S. Food and Drug Administration (FDA) for the management of various malignancies: pembrolizumab, nivolumab, atezolizumab, durvalumab and avelumab. Recent publications illustrate that in specific stages, immunotherapy is more effective than chemotherapy with a better toxicity profile (1). Currently, the only FDA-approved indication for the anti-PD-L1 monoclonal antibody durvalumab (MEDI-4736) is locally advanced or metastatic urothelial carcinoma that has progressed during or following platinum-based chemotherapy within 12 months of treatment. This article summarizes the milestones in the development of durvalumab leading to its approval for urothelial carcinoma.