SEANGWORLD FACT BRIEF · SEANGWORLDNEWS · 1 SOURCE
FDA grants accelerated approval to Etcamah combined with CDK4/6 inhibitors for treatment of advanced HR-positive, HER2-negative breast cancer with ESR1 mutation
On September 4, 2026, the U.S. Food and Drug Administration (FDA) granted accelerated approval to Etcamah (camizestrant) in combination with a CDK4/6 inhibitor (abemaciclib, palbociclib, or ribociclib) for treating adult patients with hormone receptor-positive, HER2-negative locally advanced or metastatic breast cancer with ESR1 mutation detected during aromatase inhibitor and CDK4/6 inhibitor therapy. This approval is based on progression-free survival data from a clinical trial, showing a median of 16 months for patients on the Etcamah regimen compared to 9.2 months for those continuing aromatase inhibitor therapy. The FDA also authorized the Guardant360 CDx assay as a companion diagnostic to identify eligible patients. The approval includes a boxed warning for risks related to heart rhythm irregularities and potential harm to unborn babies. Confirmatory studies are required to verify clinical benefits of early intervention based on circulating tumor DNA mutation detection. The accelerated approval was granted to AstraZeneca.
Published ET · Updated ET
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Facts
- Established fact
FDA granted accelerated approval to Etcamah in combination with a CDK4/6 inhibitor for treatment of adult patients with HR-positive, HER2-negative, locally advanced or metastatic breast cancer upon detection of ESR1 mutation during aromatase inhibitor and CDK4/6 inhibitor therapy.
- Established fact
The Guardant360 CDx assay was authorized as a companion diagnostic to identify patients with ESR1 mutations for treatment with camizestrant.
- Established fact
Clinical trial showed median progression-free survival of 16 months for patients on Etcamah and CDK4/6 inhibitor versus 9.2 months for those continuing aromatase inhibitor and CDK4/6 inhibitor.
- Established fact
FDA's accelerated approval is based on progression-free survival measured from the detection of ESR1 mutation in blood, requiring confirmatory studies to verify clinical benefit.
- Established fact
Prescribing information includes warnings for irregular heart rhythm when Etcamah is combined with certain medications, slow heart rate, and potential harm to unborn babies.
- Established fact
ESR1 mutations develop as resistance mechanisms during treatment with aromatase inhibitors; fewer than 5% of patients have these mutations at diagnosis, rising to nearly 40% after disease progression on aromatase inhibitor therapy.
What changed
FDA approved Etcamah combined with CDK4/6 inhibitors for breast cancer patients with ESR1 mutation detected during specific therapy, authorizing a companion diagnostic test.
Who is affected
Adult patients with hormone receptor-positive, HER2-negative advanced or metastatic breast cancer with ESR1 mutation during aromatase inhibitor and CDK4/6 inhibitor therapy.
What happens next
FDA mandates confirmatory studies to verify and describe the clinical benefit of Etcamah based on early mutation detection through ctDNA.
Sources
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