Natera announced a collaborative Phase II MiRaDoR trial with MEDSIR and Roche funding to evaluate Signatera ctDNA monitoring in HR+/HER2‑ early breast cancer. The study will enroll up to 60 Signatera‑positive patients without radiologic relapse into four sequential treatment arms testing endocrine therapy, giredestrant, and combinations with abemaciclib or inavolisib. The trial’s primary endpoint is a 90% reduction or clearance in baseline ctDNA at three months; serial ctDNA sampling will evaluate molecular response dynamics. The study couples MRD detection with targeted therapeutic arms, reflecting a precision‑oncology model that routes ctDNA‑positive patients into biomarker‑matched interventions rather than surveillance alone.