Evaluation of Clinical Outcomes, Tolerability, and Costs of Avelumab Maintenance and Pembrolizumab Second-Line Therapy in Advanced Urothelial Cancer.

The goal of this observational study is to evaluate the clinical outcomes, side effects, and costs of Avelumab maintenance therapy in first-line and Pembrolizumab in second-line for platinum-fit patients with advanced urothelial cancer who have not shown disease progression after 4-6 cycles of platinum-based first-line chemotherapy. Researchers will compare the effects of Avelumab (used as maintenance in first-line) and Pembrolizumab (used in second-line) to see if there are differences in clinical outcomes, toxicity profiles, and costs. Participants will: Receive Avelumab as maintenance therapy in the first-line or Pembrolizumab in the second-line as per standard clinical practice. Be monitored for clinical outcomes, side effects, and costs over a period of up to 12 months prospectively and 10 years retrospectively.