Bladder preservation therapy in combination with atezolizumab and radiation therapy for invasive bladder cancer (BPT-ART) - A study protocol for an open-label, phase II, multicenter study.

Radical cystectomy (RC) is recommended for muscle-invasive bladder cancer (MIBC) or highest-risk non-muscle-invasive bladder cancer (NMIBC). Trimodal therapy (TMT) is the most favorable strategy among bladder preservation therapies (BPT) for patients who are ineligible for or refuse RC. However, referrals for TMT, especially following chemotherapy, are limited by the patient's condition. Therefore, new BPT approaches are needed. Atezolizumab inhibits programmed death-ligand 1, is well-tolerated in patient populations heavily dominated by renal insufficiency, and is expected to have synergistic anti-tumor effects in combination with radiation therapy (RT). Therefore, we have conducted this open-label phase II multicenter study to evaluate the efficacy and safety of RT in combination with atezolizumab for T2-3 MIBC and highest-risk T1 NMIBC patients. This study was initiated in January 2019, and we aimed to enroll a total of 45 patients. The study is registered in the Japan Registry of Clinical Trials (Identifier: RCT2031180060).