A multi-institutional study published in European Urology demonstrated that quantification of urine tumor DNA (utDNA) can accurately predict recurrence risk in patients with high-risk non–muscle-invasive bladder cancer undergoing atezolizumab immunotherapy. This non-invasive biomarker supports personalized treatment strategies for BCG-unresponsive patients, who currently face limited options including radical cystectomy. The research, leveraging the SWOG S1605 clinical trial cohort, illustrates how utDNA monitoring before and during therapy offers critical prognostic information to optimize immunotherapy management.