FDA approves AstraZeneca's camizestrant for breast cancer despite negative advisory committee vote

The FDA has granted accelerated approval to AstraZeneca's camizestrant for adults with ESR1-mutated, HR-positive, HER2-negative advanced breast cancer, marking the first time a cancer treatment change is approved based on ctDNA testing rather than imaging. The approval came despite a 6-3 negative vote by an FDA advisory committee in April 2026. In the SERENA-6 trial, camizestrant improved median progression-free survival to 16 months compared to 9.2 months for continued aromatase inhibitor therapy.

FDA accelerated approval of camizestrant

• ▪The FDA required confirmatory studies to verify and describe the clinical benefit of AstraZeneca's camizestrant following its accelerated approval
• ▪The FDA granted accelerated approval to AstraZeneca's camizestrant, in combination with a CDK 4/6 inhibitor, for adults with hormone receptor-positive, HER2-negative locally advanced or metastatic breast cancer upon detection of an ESR1 mutation

Advisory committee negative vote

• ▪In April 2026, the FDA's Oncologic Drugs Advisory Committee voted 6-3 against the approval of AstraZeneca's camizestrant
• ▪Members of the FDA's Oncologic Drugs Advisory Committee objected to the approval of AstraZeneca's camizestrant because there was no evidence that patient outcomes improve when switching based on ctDNA testing rather than radiographic progression

ctDNA-guided treatment switching

• ▪Approximately 30% of breast cancer patients develop ESR1 mutations during upfront aromatase inhibitor and CDK4/6 inhibitor treatment, which causes resistance to the aromatase inhibitor
• ▪The approval of AstraZeneca's camizestrant marks the first time the FDA has approved a cancer treatment change based on circulating tumor DNA testing instead of disease progression on imaging
• ▪The FDA approved the Guardant360 CDx circulating tumor DNA assay to detect ESR1 mutations in patients undergoing aromatase inhibitor and CDK4/6 inhibitor therapy

SERENA-6 trial results

• ▪In the SERENA-6 clinical trial, switching to AstraZeneca's camizestrant improved median progression-free survival to 16 months compared to 9.2 months for patients who continued aromatase inhibitor treatment
• ▪The SERENA-6 clinical trial, which evaluated AstraZeneca's camizestrant, included 315 patients with ESR1 mutations who had been on an aromatase inhibitor and a CDK4/6 inhibitor for at least six months
• ▪In the SERENA-6 clinical trial, the median time to deterioration in patient-reported global health status and quality of life was 21 months for the AstraZeneca camizestrant group compared to 6.4 months for the continued aromatase inhibitor group

QTc prolongation boxed warning

• ▪The prescribing information for AstraZeneca's camizestrant includes a boxed warning on QTc interval prolongation when used with other drugs that prolong the QTc interval
• ▪The prescribing information for AstraZeneca's camizestrant includes warnings and precautions for bradycardia and embryo-fetal toxicity

Prescribing dosage information

• ▪During AstraZeneca camizestrant treatment, the accompanying CDK4/6 inhibitor is continued at the same dose as when the ESR1 mutation was first detected
• ▪The recommended dosage for AstraZeneca's camizestrant is 75 mg taken orally once daily, with or without food, until disease progression or unacceptable toxicity

Debatable claims

• ▪The FDA should approve cancer treatment changes based on ctDNA testing instead of imaging
• ▪The FDA was justified in approving camizestrant despite the advisory committee's negative vote

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