Integrating ctDNA-Based MRD Testing in MIBC

In this segment, panelists provided an overview of the Signatera ctDNA assay, explaining its tumor-informed design that tracks up to 16 patient-specific mutations through plasma PCR, offering greater accuracy than panel-based tests due to reduced false positives from CHIP. They reviewed pivotal findings from the IMvigor-011 trial, which prospectively validated results from IMvigor-010, demonstrating that atezolizumab significantly improved overall and disease-free survival in ctDNA-positive patients, including those who converted from negative to positive post-surgery. Panelists emphasized that these findings confirm ctDNA as a valuable tool for guiding adjuvant immunotherapy decisions in checkpoint inhibitor–naïve patients, while integration with perioperative regimens like NIAGARA or EV-303 remains to be clarified. They contrasted tumor-informed assays with faster, methylation-based non–tumor-informed tests (e.g., Guardant), noting trade-offs between turnaround time and sensitivity. Panelists highlighted the promise of longitudinal ctDNA monitoring to enable “treat-upon–molecular-recurrence” approaches in future adjuvant strategies.