FDA Approves Guardant360 CDx as Companion Diagnostic for AstraZeneca's Breast Cancer Drug

Key Facts

1The U.S. FDA approved Guardant360 CDx to identify advanced breast cancer patients with ESR1 mutations for treatment with AstraZeneca's ETCAMAH.

In a move that advances precision medicine within the oncology sector, the U.S. Food and Drug Administration (FDA) has approved the Guardant360 CDx test as a companion diagnostic for AstraZeneca's latest breast cancer treatment. According to reports, the approval allows the liquid biopsy test to identify advanced breast cancer patients with ESR1 mutations who are eligible for therapy with ETCAMAH (camizestrant). This regulatory milestone aims to assist clinicians in identifying specific genetic markers in patients with HR-positive, HER2-negative advanced breast cancer.

The partnership between Guardant Health and AstraZeneca highlights a strategic push to integrate diagnostic tools with pharmaceutical therapies to expand market reach. Analyst assessments suggest that this FDA approval enhances the clinical utility for both the diagnostic provider and the pharmaceutical developer. Per market data, AstraZeneca's primary listings include AZN and AZN.L, which remain focal points for investors tracking the commercial rollout of companion diagnostics in the oncology market.

At the close on September 4, 2026, AZN was priced at $161.40, having reached a day high of $163.78. Similarly, the London-listed AZN.L closed at 12,006 pence on the same date. With no major upcoming sector-specific catalysts in the economic calendar for the next week, market participants will likely monitor the stock's performance relative to its recent trading range between $161.36 and $163.78.