FDA grants accelerated approval to AstraZeneca's camizestrant combo

The U.S. Food and Drug Administration has granted accelerated approval to AstraZeneca's (NYSE: AZN) ETCAMAH (camizestrant) in combination with a CDK4/6 inhibitor for the treatment of adult patients with hormone receptor-positive, HER2-negative locally advanced or metastatic breast cancer, upon detection of an ESR1 mutation during aromatase inhibitor and CDK4/6 inhibitor therapy.

The approval covers use alongside three CDK4/6 inhibitors: abemaciclib, palbociclib, or ribociclib. Detection of the ESR1 mutation must be confirmed using an FDA-authorized test. Concurrently, the FDA approved a companion diagnostic to detect emerging ESR1 resistance mutations in circulating tumor DNA.

The accelerated approval was based on results from the SERENA-6 Phase III trial, which were presented at the 2025 American Society of Clinical Oncology Annual Meeting and published in The New England Journal of Medicine. In a planned interim analysis, ETCAMAH combined with a CDK4/6 inhibitor reduced the risk of disease progression or death by 56% compared with a standard aromatase inhibitor plus CDK4/6 inhibitor regimen, with a median progression-free survival of 16.0 months versus 9.2 months (hazard ratio 0.44; 95% CI: 0.31–0.60; p<0.00001).

A subsequent pre-planned analysis showed a statistically significant improvement in time to second disease progression of 25.7 months versus 19.1 months (hazard ratio 0.63; 95% CI: 0.46–0.86; p=0.00373). Overall survival data remained immature and will continue to be assessed.

The trial enrolled 315 patients whose tumors developed ESR1 mutations during first-line treatment, without clinical disease progression. Approximately 30% of patients with endocrine-sensitive HR-positive disease develop ESR1 mutations during first-line treatment before progression, according to the press release.

The most common adverse reactions occurring in at least 20% of patients included decreased neutrophils (68%), decreased leukocytes (66%), decreased hemoglobin (47%), visual disturbances (34%), and fatigue (23%). The drug carries a boxed warning for arrhythmia risk when used with QTc interval-prolonging drugs, including ribociclib.

ETCAMAH is also approved in more than 30 countries, including the EU, Japan, Canada, and the UK, based on the same trial data. The accelerated approval may be contingent on results from a confirmatory trial.

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