SignateraTM MRD Identifies Breast Cancer Patients Who Can Forgo Surgery

Key Takeaways

• 68% baseline MRD‑negative patients avoided progression
• All MRD‑positive cases flagged progression before imaging
• 64% of MRD‑positive cleared ctDNA after six months
• Over 80% said test reduced decision anxiety

Summary

Natera’s Signatera circulating‑tumor DNA test was shown in a prospective Clinical Cancer Research study to identify older women (≥70) with early‑stage ER⁺/HER2‑ breast cancer who can safely forgo surgery and remain progression‑free on primary endocrine therapy. Baseline MRD‑negative patients (68% of the cohort) experienced zero progression, delivering a 100% negative predictive value. Among MRD‑positive patients, 64% cleared ctDNA after six months of endocrine therapy, and all seven remained free of distant disease, while the test flagged progression before imaging in every case that later progressed. Over 80% of participants reported that Signatera helped guide treatment decisions without increasing anxiety.

Pulse Analysis

The emergence of circulating‑tumor DNA (ctDNA) assays has reshaped precision oncology, offering real‑time insight into tumor dynamics without invasive procedures. Signatera, Natera’s personalized MRD test, sequences patient‑specific mutations to detect trace amounts of ctDNA in blood. For women over 70 with hormone‑receptor‑positive, HER2‑negative breast cancer, primary endocrine therapy (pET) presents a less aggressive alternative to surgery, but clinicians have lacked robust tools to gauge who can safely avoid an operation. This study provides that missing molecular stratification layer, aligning molecular remission with clinical outcomes.

In the prospective cohort of 43 seniors who elected pET, baseline Signatera testing identified 23 MRD‑negative patients who experienced no disease progression, establishing a 100% negative predictive value. Conversely, the 11 MRD‑positive participants demonstrated a 100% longitudinal sensitivity, with ctDNA signals preceding radiographic evidence of progression. Notably, 64% of the MRD‑positive group cleared ctDNA after six months of endocrine therapy, and all remained free of distant metastasis, underscoring ctDNA’s role as an early response marker. The patient‑reported data—over 80% felt more confident in their treatment plan—suggests the test also mitigates decision‑making anxiety, a critical factor for older adults balancing treatment benefits against surgical risk.

From a market perspective, these results position Natera at the forefront of non‑surgical breast‑cancer management, a niche likely to attract payer interest given the potential cost savings from avoided surgeries and associated complications. As guidelines evolve to incorporate molecular monitoring, Signatera could become a standard companion diagnostic for endocrine‑only strategies, spurring broader adoption across oncology practices. Continued validation in larger, diverse cohorts will be essential to cement regulatory acceptance and secure reimbursement pathways, ultimately expanding personalized care for an aging patient population.