Avelumab Maintenance Therapy in Patients With Curatively Unresectable Urothelial Carcinoma in Japan: Subgroup Analyses of Post-Marketing Surveillance Data by Age, Prior Chemotherapy Regimen, and Best Overall Response to Prior Chemotherapy.

INTRODUCTION: Avelumab maintenance therapy was approved in Japan for curatively unresectable urothelial carcinoma (UC) without progression after prior platinum-based chemotherapy (PBC) based on results from the JAVELIN Bladder 100 phase 3 trial. We report post hoc analyses of post-marketing surveillance (PMS) data in subgroups defined by age, prior PBC regimen, and best overall response (BOR) to prior PBC. METHODS: Patients with curatively unresectable UC who received ≥ 1 dose of avelumab maintenance in Japan between February and December 2021 were evaluated. The primary objective was to evaluate safety based on prespecified adverse drug reactions (ADRs). The secondary objective was to evaluate effectiveness, including time to treatment failure (TTF; discontinuation for any reason) and overall survival (OS). RESULTS: The analysis population included 453 patients. In patients aged ≤ 64 (n = 75), 65 to 74 (n = 198), or ≥ 75 (n = 180) years, prespecified ADRs occurred in 17 (22.7%), 69 (34.9%), and 58 (32.2%); median TTF was 4.8, 4.4, and 4.9 months; and 12-month OS rates were 77.6%, 82.7%, and 72.6%, respectively. In patients with prior cisplatin + gemcitabine (n = 267), carboplatin + gemcitabine (n = 163), or dose-dense methotrexate, vinblastine, doxorubicin, and cisplatin (n = 9) treatment, prespecified ADRs occurred in 93 (34.8%), 45 (27.6%), and 3 (33.3%); median TTF was 4.6, 4.6, and 5.1 months; and 12-month OS rates were 79.6%, 73.8%, and 88.9%, respectively. In patients with prior complete response (n = 47), partial response (n = 242), or stable disease (n = 149), prespecified ADRs occurred in 16 (34.0%), 79 (32.6%), and 45 (30.2%); median TTF was 5.2, 4.6, and 4.6 months; and 12-month OS rates were 89.4%, 76.3%, and 75.8%, respectively. DISCUSSION: In this PMS population, safety and effectiveness were observed with avelumab maintenance therapy across subgroups defined by age, prior PBC regimen, or BOR to prior PBC. Findings support the favorable benefit-risk profile of avelumab maintenance in clinical practice. TRIAL REGISTRATION: University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR: UMIN 43435).