Urinary Tumor DNA-Guided Systemic Immunotherapy for Unresectable Very-High-Risk Non-Muscle-Invasive Bladder Cancer

This study evaluates whether urinary tumor DNA (utDNA) testing, together with clinical, pathologic, and radiographic assessment, can help guide treatment discontinuation and active surveillance in patients with unresectable very-high-risk non-muscle-invasive bladder cancer (VHR NMIBC) treated with bladder-sparing systemic immunotherapy. Participants receive systemic immune checkpoint inhibitor-based therapy every 3 weeks for an initial 3 cycles. Initial response assessment is performed using transurethral resection of bladder tumor (TURBT) and chest and abdominopelvic computed tomography (CT). Participants without progression to muscle-invasive, regional nodal, or distant metastatic disease then undergo post-TURBT urine cytology and urinary tumor DNA (utDNA) testing. Participants with both negative urine cytology and negative utDNA results receive an additional 3 cycles of systemic immunotherapy. After the additional treatment, participants undergo repeat evaluation using cystoscopy with biopsy, urine cytology, utDNA testing, and chest and abdominopelvic CT. Participants with negative findings on cystoscopic biopsy, urine cytology, and utDNA testing, and without radiographic evidence of nodal or distant metastatic disease, discontinue systemic immunotherapy and enter an active surveillance phase with regular follow-up monitoring. Participants who do not meet these criteria continue further clinical management and follow-up according to institutional practice. The study aims to determine whether a shortened duration of systemic immunotherapy guided by integrated molecular, clinical, pathologic, and radiographic response assessment can maintain favorable oncologic outcomes while reducing unnecessary treatment exposure in this high-risk population.