Bladder Preservation Therapy in Combination with Atezolizumab and Radiation Therapy (BPT-ART) for Invasive Bladder Cancer: Final Analysis from a Multicentre, Open-label, Prospective Phase 2 Trial

Radical cystectomy (RC) is the standard care for muscle-invasive or very high-risk non-muscle-invasive bladder cancer (BC), but optimal management for bladder preservation remains uncertain. In this multicentre, open-label, phase 2 trial, patients with cT1-3 N0 M0 muscle-invasive BC received radiation therapy (RT; 41.4 Gy to the small pelvis and 16.2 Gy to the whole bladder) and atezolizumab (1200 mg) every 3 wk. The primary endpoint was progression-free survival (PFS) at 3 yr. Key secondary endpoints included the clinical complete response (cCR) rate at 24 wk, overall survival (OS), and the bladder-intact recurrence-free rate (BIRFR). From 2019 to 2021, 41 of the 45 patients enrolled received treatment. The median age was 71 yr and most patients (73%) had T2 tumours. At 24 wk, 84% achieved cCR. The 3-yr PFS rate was 70% (95% confidence interval CI 54-81%), with the lower limit of the 95% CI exceeding the prespecified threshold of 45%. The 3-yr OS rate was 91% and the 3-yr BIRFR was 89%. Grade ≥3 adverse events occurred in 55% of patients, but no treatment-related deaths were observed. Limitations include the single-arm design and cohort size. Bladder preservation therapy with atezolizumab and RT showed favourable treatment effects with manageable toxicity for patients unfit for or refusing RC.