The IMvigor011 trial tested circulating tumor DNA (ctDNA)-guided bladder cancer therapy in patients with muscle-invasive disease after surgery.[3][4] More than 760 patients were monitored with regular blood tests for ctDNA after surgical removal of the tumor.[3] Patients with positive ctDNA were randomly assigned to atezolizumab (immunotherapy) or placebo, while patients with negative ctDNA received no further treatment.[3][4] In ctDNA positive patients, atezolizumab reduced the risk of relapse by 36% and the risk of death by 41% compared to placebo.[4] Patients with persistently negative ctDNA had a low risk of cancer recurrence: 95% disease-free at one year and 88% at two years, 89% free of recurrence at a median follow-up of 21.8 months.[3][4] The study provided the first level 1 evidence for an intervention based on positive ctDNA in the adjuvant setting and was presented at ESMO 2025 and published in the New England Journal of Medicine.[1][3] The safety profile of atezolizumab was similar to that known, with grade 3 or 4 adverse events in 28% of patients on the drug versus 22% on placebo.[1]