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NewsEurope approves Guardant360 CDx as a companion diagnostic for camizestrant in advanced breast cancer. The blood-based test detects ESR1 mutations in circulating tumor DNA, helping identify patients who may benefit from switching therapies before disease progression. This follows similar approvals in the US and Japan, cementing the test's global role in precision oncology.
Europe has given the green light to Guardant360 CDx as a companion diagnostic for camizestrant (Etcamah) in patients with ER-positive, HER2-negative locally advanced or metastatic breast cancer. The liquid biopsy test detects ESR1 mutations in blood-based circulating tumor DNA, enabling clinicians to identify patients who may benefit from switching to camizestrant — even before radiographic disease progression is visible. The EU approval follows similar companion diagnostic clearances in the US and Japan.
The move is backed by data from the phase 3 SERENA-6 trial, which showed that patients who switched to camizestrant upon detecting an emergent ESR1 mutation had significantly longer progression-free survival compared to those who continued aromatase inhibitor therapy. The European Commission had approved camizestrant itself in July 2026 for use in combination with a CDK4/6 inhibitor.
By the Numbers:
Why it matters: This approval expands access to a ctDNA-guided treatment strategy across Europe, offering oncologists a proactive tool to adapt therapy based on molecular signals — potentially delaying disease progression and improving outcomes for breast cancer patients.
