Evaluating the survival benefits of adjuvant immunotherapy in muscle-invasive urothelial carcinoma: A real-world experience.

750 Background: Despite current guidelines recommendations to administer adjuvant nivolumab following radical cystectomy (RC) in patients with adverse pathologies, regardless of prior neoadjuvant chemotherapy (NAC), evidence on the long-term efficacy of ICIs remains sparse. This study aims to evaluate the potential survival benefits of the two most common ICIs, Nivolumab and Pembrolizumab, in patients with muscle-invasive bladder cancer (MIBC) at a single institution. Methods: We queried our IRB-approved, prospectively maintained institutional RC database for all patients who underwent RC from January 2017 (following FDA approval for ICIs in MIBC) to July 2022. Patients with pT3-4a and/or N+ after RC, or ypT2-4a and/or N+ after NAC + RC, were included and categorized into two groups: those who received adjuvant ICI (ICI+) and those who did not (ICI-). Demographic, clinical, and survival data were retrieved from our database. Multivariable Cox regressions were performed to adjust for potential confounding variables. Results: A total of 191 patients were included, with 38 (19.9%) receiving adjuvant ICI (30 Nivolumab and 8 Pembrolizumab). The table outlines the patient characteristics, stratified by adjuvant ICI treatment. With a median follow up of 17.9 months, overall survival (OS) was 97.4% in the ICI+ group and 66.0% in the ICI- group (p = .003). Recurrence-free survival (RFS) was 84.2% and 67.9% in the ICI+ and ICI- groups, respectively (p=.206). in the ICI- group, 10 out of 49 (20.4%) recurrences were local or regional (i.e. urethral or ureteral), while all recurrences (N=6) in the ICI+ group were distant. Multivariable Cox regressions demonstrated that, after adjusting for age and pathological stage, adjuvant ICI was associated with significantly improved OS (HR = 0.08 [95%CI: 0.01, 0.59], p = .013), but not RFS (HR = 0.43 [95%CI: 0.18, 1.04], p = .062). Conclusions: Our results corroborated the beneficial effect of ICIs on OS. Although the improvement in RFS did not reach statistical significance, ICIs showed a trend toward positive clinical impact. A notable finding was the potential for ICIs to alter the recurrence pattern in MIBC. Although limited by a small sample size, this study represents one of the first real-world evaluations of adjuvant ICI efficacy in a single-institution cohort. Demographics and baseline clinical characteristics. ICI+ (N=38) ICI- (N=153) p Age (years) 68.7 ± 8.6 71.6 ± 10.4 .060 Sex (Male) 27 (71.1%) 118 (77.1%) .433 Charleson Comorbidity Index 0 9 (23.7%) 31 (20.3%) .886 1 6 (15.8%) 27 (17.6%) ≥ 2 23 (60.5%) 95 (62.1%) Pathological staging OC (< (y)pT2; pN0) 3 (7.9%) 29 (19.0%) .013 EV (> (y)pT2; pN0) 11 (28.9%) 67 (43.8%) LN+ (pN+) 24 (63.2%) 57 (37.2%) Neoadjuvant Chemotherapy (yes) 30 (79.0%) 85 (55.6%) .008