Maintenance therapy with avelumab as the first-line treatment in patients with metastatic urothelial carcinoma: A real-world, ambispective RAVE-Bladder study.

e16569 Background: The RAVE-Bladder study was designed to assess the efficacy and safety of avelumab maintenance in patients with metastatic urothelial carcinoma in a real-world population. Methods: In this non-interventional, ambispective study, eligible patients had metastatic urothelial carcinoma and measurable disease that had not progressed with first-line platinum-based chemotherapy. Patients received maintenance avelumab according to a standard regimen (800 mg, administered every 2 weeks). Tumor imaging was performed at baseline and then every 12 weeks. The primary endpoint was overall survival (OS) at the initiation of avelumab treatment, while secondary endpoints included progression-free survival (PFS), objective response rate (ORR), and safety. Results: At data cutoff (February 02, 2024), 110 patients (81% male, 19% female) were recruited from 21 sites and median follow-up was 9.71 months. Median age was 65 (range, 36-84) years. All patients had confirmed urothelial carcinoma (high grade, 62.8%). Primary tumor site was upper urinary tract in 26 (23.6%) and bladder in 84 (76.4%) cases. Forty-five (40.9%) patients had radical surgery; 68 (61.8%) had metastatic disease at time of diagnosis; 44 (40%) had 2 and more metastatic sites. First-line chemotherapy included gemcitabine + cisplatin, gemcitabine + carboplatin, cisplatin only, carboplatin only, and MVAC in 51 (46.4%), 32 (29%), 19 (17.3%), 7 (6.4%), and 1 (0.9%) patients, respectively. Median number of chemotherapy cycles was 4 (range, 3-9) and median number of avelumab infusions was 16 (range, 2-43). ORR to chemotherapy was 48.2%. An additional 38 patients (34.6%) responded to avelumab therapy (16 CR, 22 PR). Median OS was not reached and 1-year OS rate was 78.7%. Median PFS was 9.5 months (95% CI 7.8 – 11.2 months). Thirteen (11.8%) patients experienced grade 3 adverse events during avelumab therapy. Conclusions: The findings illustrate the favorable tolerability of maintenance therapy with avelumab, a remarkable progression-free interval subsequent to standard platinum-containing chemotherapy and prominent additional response rate among patients with metastatic urothelial carcinoma. Ongoing follow-up continues to provide additional insights. Clinical trial information: KCRB01012022 .