Real-world efficacy of enfortumab vedotin in Japanese patients with metastatic urothelial carcinoma stratified by EV-301 trial eligibility: a multicenter Bayesian restricted mean survival time analysis

BACKGROUND: Enfortumab vedotin (EV) exhibited superior efficacy in the EV-301 trial; however, real-world outcomes stratified by trial eligibility criteria remain unclear. We evaluated the real-world efficacy of EV in Japanese patients with metastatic urothelial carcinoma (mUC) via EV-301 eligibility stratification and restricted mean survival time (RMST) analysis. METHODS: This multicenter retrospective study analyzed 115 Japanese mUC patients treated with EV following platinum-based chemotherapy and immune checkpoint inhibitors. Patients were categorized as eligible (n = 81, 70.4%) or ineligible (n = 34, 29.6%) based on EV-301 criteria. The primary endpoint was overall survival (OS) evaluated via RMST at multiple time points. Reconstructed individual patient data from EV-301 enabled comparative analysis, with Bayesian power prior methodology integrating evidence sources. RESULTS: Eligible patients exhibited significantly higher OS than ineligible ones (HR 2.19, 95% CI 1.24-3.89, P = .009). RMST analysis at 12 months revealed OS of 9.65 months (95% CI 8.67-10.63) and 7.11 months (4.79-9.44) in eligible and ineligible patients, respectively. Significant RMST differences were observed between the eligible and ineligible groups at 6 months (1.18 months, P = .017) and 12 months (2.54 months, P = .049). Bayesian analysis with moderate borrowing (α = 0.5) revealed posterior RMST of 9.40 months (95% credible intervals 8.80-9.98) at 12 months. Eligible patients showed comparable RMST outcomes to EV-301 trial participants, with no significant differences. CONCLUSIONS: EV exhibited real-world efficacy in Japanese mUC patients comparable to the eligible patients' outcomes in the EV-301 trial. Ineligible patients showed statistically inferior outcomes.