The FDA approved Genentech’s Tecentriq (atezolizumab) and Tecentriq Hybreza as adjuvant therapy for muscle-invasive bladder cancer patients with circulating tumor DNA after cystectomy, using Natera’s Signatera CDx as the companion test. The approval makes ctDNA MRD the basis for selecting patients for immunotherapy in the post-surgical setting. In the Phase III IMvigor011 trial, patients with ctDNA-positive results randomized to Tecentriq had a disease-free survival of 9.9 months versus 4.8 months with placebo, with median overall survival of 32.8 months versus 21.1 months. The study also reported a high proportion of survival among Signatera-negative patients who avoided adjuvant treatment. The approval also authorizes Signatera as a CDx for identifying patients likely to benefit from Tecentriq or Tecentriq Hybreza, marking the first FDA authorization for a blood-based MRD assay used this way. Genentech and Natera framed the decision as a step toward reducing unnecessary therapy based on molecular residual disease. Regulatory approval of an MRD-guided adjuvant regimen is likely to shift post-cystectomy workflows toward serial blood testing and away from purely radiographic staging for treatment decisions.