Immunotherapy maintenance therapy for advanced urothelial carcinoma (aUC): a comprehensive review

Immunotherapy has revolutionized the systemic treatment of solid tumors, including advanced urothelial carcinoma (aUC), providing durable responses with a favorable safety profile. Multiple immune checkpoint inhibitor agents have been approved in monotherapy in second-line setting, and for a selected group of chemo-naïve cisplatin-ineligible patients with high PD-L1 expression. Despite the incorporation of immunotherapy to the systemic treatment landscape of aUC, platinum-based chemotherapy remains the standard of care in frontline setting for vast majority of patients. Urothelial carcinoma is a chemosensitive disease with response rates of up to 50% to frontline chemotherapy. However, the response to chemotherapy is short lasting with vast majority of patients experiencing disease progression and death within months. In this context, maintenance therapy constitutes an attractive therapeutic strategy to maximize the time to treatment failure. Different cytotoxic and targeted agents have been investigated as maintenance therapy for aUC but have not shown an impact on survival. Avelumab has become the first and only drug to improve overall survival as maintenance therapy after frontline platinum-based therapy in aUC patients and the first drug to be approved in this setting. This article will review the rational for maintenance therapy, the different drugs investigated as maintenance therapy for aUC, and the impact of avelumab maintenance therapy as a new standard of care in the management of aUC.