Avelumab first-line (1L) maintenance treatment in patients with locally advanced or metastatic urothelial carcinoma (la/mUC) in the Czech Republic: Updated real-world results from a national reimbursement registry.

693 Background: Platinum-based chemotherapy followed by avelumab 1L maintenance treatment for patients with nonprogressive disease is a standard of care in la/mUC. In the Czech Republic, following EU approval, there is a requirement to provide real-world data for “highly innovative medicinal products” and obtaining reimbursement requires registry creation for data collection. Interim results from a retrospective analysis of a national reimbursement registry for avelumab 1L maintenance treatment in the Czech Republic were reported previously; here, we report longer-term results. Methods: Registry data were collected by the Health Insurance Bureau for patients with la/mUC receiving avelumab 1L maintenance treatment between Oct 2021 and Jan 2024. The primary endpoint was overall survival (OS) from start of avelumab 1L maintenance (index date); secondary endpoints included progression-free survival (PFS) and safety. Descriptive statistics were used to analyze the data. OS, PFS, and probability of ongoing response were estimated using the Kaplan-Meier method. Results: Overall, 107 patients with la/mUC were treated with avelumab 1L maintenance (77 male/30 female). 1L platinum-based chemotherapy was cisplatin based in 55 patients (51.4%) and carboplatin based in 46 patients (43.0%); 6 patients (5.6%) switched regimens. At the start of avelumab, median age was 72 years (range, 45-92), and 41 patients (38.3%) had visceral metastases. Median follow-up was 8.2 months (range, 0-26.2). Median duration of avelumab treatment was 9.7 months (range, 1.0-29.2). The table shows effectiveness data for avelumab 1L maintenance. Overall, 16 adverse events were reported in 18 patients (16.8%), including 1 patient with a grade 3 infusion reaction and 2 patients with grade 2 diarrhea. At data cutoff (Jan 31, 2024), 88 patients were alive, and 23 had started subsequent treatment. Conclusions: These updated data are generally consistent with results from the JAVELIN Bladder 100 phase 3 trial and other real-world studies, supporting the effectiveness and favorable safety profile of avelumab as 1L maintenance treatment in patients with la/mUC that has not progressed with 1L platinum-based chemotherapy. N=107 Median OS, months Not reached OS rate, % (95% CI) 6 months12 months18 months 93.4 (88.4-98.7)79.3 (69.8-90.2)68.0 (54.6-84.6) Median PFS, months (95% CI) 11.0 (8.6-not estimable) PFS rate, % (95% CI) 6 months12 months18 months 67.8 (58.7-78.2)48.9 (38.8-61.6)39.1 (27.5-55.4) Objective response rate, n (%) Complete response Partial response 29 (27.1)12 (11.2)17 (15.9) Median duration of response, months Not reached Probability of ongoing response, % (95% CI) 6 months12 months18 months 91.1 (80.0-100)80.4 (64.7-99.8)80.4 (64.7-99.8) Median time to response, months 3.4 (1.8-18.2)