Bridging trial and practice: Real-world data of adjuvant nivolumab in high-risk muscle-invasive urothelial carcinoma.

710 Background: Adjuvant immune checkpoint inhibition with nivolumab has demonstrated efficacy in randomized clinical trials for patients with high-risk muscle-invasive urothelial carcinoma (MIUC). However, its effectiveness in real-world clinical practice remains unclear. We aimed to evaluate the prognostic impact of adjuvant nivolumab compared with conventional adjuvant chemotherapy or observation in a multicenter Japanese cohort. Methods: We retrospectively analyzed 366 patients with high-risk IMUC (bladder or upper tract urothelial carcinoma: UTUC) who underwent radical surgery between 2016 and 2025 across 22 institutions in the AGEHA database. Among them, 126 received adjuvant nivolumab, 59 received adjuvant chemotherapy, and 181 had no adjuvant therapy. Primary endpoints were disease-free survival (DFS) and overall survival (OS). Kaplan–Meier curves, Cox proportional hazards models, and propensity score matching were applied to adjust for baseline imbalances. Subgroup analyses were performed in patients with prior neoadjuvant chemotherapy (NAC). Results: Adjuvant nivolumab was associated with improved DFS (HR 0.63, 95% CI 0.43–0.94) and OS (HR 0.54, 95% CI 0.28–1.03) compared with chemotherapy or no adjuvant therapy. After propensity score matching, both DFS (HR 0.48, 95% CI 0.31–0.74; p < 0.005) and OS (HR 0.42, 95% CI 0.22–0.80; p = 0.010) remained significantly better in the adjuvant nivolumab group. Subgroup analysis showed consistent benefits in patients with prior NAC. Limitations include the retrospective design and potential residual confounding despite adjustment. Conclusions: This multicenter real-world analysis demonstrated that adjuvant nivolumab after radical surgery significantly prolongs DFS and OS in patients with high-risk urothelial carcinoma. These findings bridge the gap between trial and practice, supporting adjuvant nivolumab as a standard option in real-world settings.