FDA Clears Blood-Based Companion Diagnostic for Advanced Breast Cancer Therapy

Endocrine therapy resistance remains a significant challenge in estrogen receptor–positive, human epidermal growth factor receptor 2–negative (HER2-) advanced breast cancer, where tumor evolution can limit the effectiveness of standard treatments. Mutations in the estrogen receptor 1 gene (ESR1) are a recognized mechanism of resistance and are frequently found in advanced disease. Rapid, non-invasive detection of these mutations can help guide timely therapy selection. A newly approved blood-based test now enables identification of ESR1 mutations to inform treatment decisions in this setting.

Guardant Health’s (Palo Alto, CA, USA) Guardant360 CDx liquid biopsy has received U.S. Food and Drug Administration (FDA) approval as a companion diagnostic for VEPPANU (vepdegestrant). The authorization allows use of the assay to identify adults with ER-positive, HER2-negative, ESR1‑mutated advanced or metastatic breast cancer, as detected by an FDA‑authorized test, whose disease has progressed following at least one line of endocrine therapy. The approval enables clinical laboratories to use a validated, blood-based method to determine eligibility for the targeted therapy.

Guardant Health Guardant360 CDx is recognized as the first FDA-approved liquid biopsy for comprehensive genomic profiling. The test detects multiple genomic alterations across all solid tumors and has existing companion diagnostic indications spanning non–small cell lung cancer, breast cancer, and colorectal cancer. In this indication, the assay provides a non‑invasive approach to identify ESR1 mutations from a simple blood draw, aligning with the need to make treatment decisions when tissue biopsy may be impractical.

According to the company, the approval is supported by clinical data demonstrating the utility of identifying ESR1 mutations to guide treatment selection in ER‑positive, HER2‑negative advanced breast cancer. This clearance represents Guardant’s third companion diagnostic approval related to ESR1 and the 26th companion diagnostic indication for the platform across multiple tumor types. The company also notes broad coverage for the assay by Medicare and commercial payers, representing more than 300 million covered lives.

“This latest FDA approval using Guardant360 CDx reflects where cancer care is headed using blood-based testing to detect resistance earlier and guide smarter treatment decisions,” said Helmy Eltoukhy, Guardant Health chairman and co-CEO. “By identifying ESR1 mutations with just a simple blood draw, we’re helping bring more precise, personalized options to patients when they need them most.”

Related Links
Guardant Health