Clinical outcomes in patients with locally advanced or metastatic urothelial cancer (la/mUC) in France treated with avelumab first-line maintenance (1LM): A real-world observational study using the French National Healthcare Database (Système National des Données de Santé SNDS).

740 Background: Avelumab 1LM is a recommended treatment for patients with la/mUC without disease progression following 1L platinum-based chemotherapy. This study aimed to describe treatment patterns and outcomes in patients with la/mUC receiving avelumab 1LM treatment in routine clinical practice in France, using the SNDS database, which covers 99% of the national population. Methods: In this retrospective, noninterventional study, adults with unresectable la/mUC (ICD-10 codes: C65-C68.0, D09.0) with prior 1L chemotherapy (Z51.1) who received avelumab 1LM treatment between Jan 1 and Dec 31, 2021, were identified. Patients were followed up until death or end of follow-up (Dec 31, 2022), whichever occurred first. The overall primary study objective was to describe the clinical course of patients; secondary objectives included describing patient characteristics and overall survival (OS). Duration of treatment and OS were analyzed using the Kaplan-Meier method. OS was assessed in the overall population and subgroups with laUC or mUC. Results: In 1,090 patients with UC (any stage) who received avelumab 1LM following 1L chemotherapy, 892 (82%) were male, median age was 72 years (≥75 years in 321 29%), and 537 (49%) had metastatic disease. Patients received 1L chemotherapy for a median of 3.6 months (IQR, 2.5-4.4) before starting avelumab 1LM, and the treatment-free interval from end of chemotherapy to start of avelumab was 10 weeks in 418 (38%), 583 (53%), and 89 (8%) patients, respectively. Median duration of avelumab 1LM treatment was 4.8 months (IQR, 2.1-10.3). At last follow-up, 658 patients (60%) were alive, 279 (26%) remained on avelumab, and 512 (47%) had received second-line treatment (63% of patients who discontinued avelumab). Median OS from the start of avelumab 1LM treatment was 22.1 months (95% CI, 19.6-26.5), and 1- and 2-year OS rates were 69% and 47%, respectively. No difference in OS was observed between subgroups with laUC (median, 22.2 months 95% CI, 18.8-not estimable) or mUC (median, 20.7 months 95% CI, 18.1-26.5). Additional effectiveness outcomes and subsequent treatment will be reported. Conclusions: This large observational study, using national data from France, supports findings from previous real-world studies showing the effectiveness of avelumab 1LM treatment in patients with la/mUC, irrespective of disease stage at treatment initiation. Results were generally consistent with an earlier study of avelumab 1LM treatment in France (AVENANCE; N = 595).