Real-world efficacy and sequential therapy patterns after avelumab maintenance in metastatic urothelial carcinoma: a Brazilian multicenter retrospective cohort study.

INTRODUCTION: Avelumab is approved as maintenance therapy after platinum-based chemotherapy in metastatic urothelial carcinoma (mUC). Real-world evidence is needed to validate outcomes and define its role in the era of newly approved agents. PATIENTS AND METHODS: This retrospective study included patients with mUC from a Brazilian multicenter oncology network (2021-2026) who received ≥1 cycle of avelumab following chemotherapy. The primary endpoint was overall survival (OS), defined as the time from avelumab initiation to death from any cause. Secondary endpoints included progression-free survival (PFS), treatment-related toxicity, and subsequent therapies after progression. Survival outcomes were estimated using the Kaplan-Meier method. RESULTS: Forty-six patients were included (63% male), with a median age of 71 years (range, 55-91). At a median follow-up of 24.4 months, 56.5% were alive, and 43.5% had died. Median treatment duration was 8.48 months, with a median of 19 cycles (range, 1-112). Median OS was not reached. Estimated OS rates at 12 and 36 months were 76.1% (95% CI, 65-89%) and 53% (95% CI, 40-71%), respectively. A PFS event occurred in 67.4% of patients, while 32.6% remained progression-free. After progression, 45.6% received second-line therapy, and 13% received third-line therapy. Median time to next treatment was 5.6 months. Grade 3-4 adverse events occurred in 26%, with no treatment-related deaths. CONCLUSION: Avelumab maintenance demonstrated durable disease control, prolonged survival, and acceptable tolerability in an unselected real-world mUC population. Nearly half of the patients received subsequent therapy after progression.