FDA grants accelerated approval to camizestrant with a CDK4/6 inhibitor for ESR1-Mutated HR-positive, HER2-negative locally advanced or metastatic breast cancer
Regulatory approval: On Sept 4, 2026, the FDA granted accelerated approval to camizestrant (Etcamah) plus a CDK4/6 inhibitor (abemaciclib, palbociclib, or ribociclib) for adults with HR-positive, HER2-negative locally advanced or metastatic breast cancer with an ESR1 mutation detected during aromatase inhibitor (AI) + CDK4/6 inhibitor therapy using an FDA-authorized test. Approval was based on SERENA-6 PFS results; OS was not mature. Guardant360 CDx was approved as a companion diagnostic.
FDA accelerated approval (Sept 4, 2026)
The FDA granted accelerated approval to camizestrant (Etcamah; AstraZeneca), an estrogen receptor antagonist, in combination with a CDK4/6 inhibitor (abemaciclib, palbociclib, or ribociclib) for adults with HR-positive, HER2-negative locally advanced or metastatic breast cancer with ESR1 mutation detected during AI + CDK4/6 inhibitor therapy, as identified by an FDA-authorized test.
The FDA also approved Guardant360 CDx as a companion diagnostic to identify patients with ESR1 mutations for treatment with camizestrant.
Supporting evidence: SERENA-6 (NCT04964934)
SERENA-6 was a randomized, double-blind, placebo-controlled, multicenter trial evaluating switching to camizestrant + CDK4/6 inhibitor vs continuing AI (anastrozole or letrozole) + CDK4/6 inhibitor in adult patients with ER-positive, HER2-negative locally advanced/metastatic disease and detectable ESR1 mutations by ctDNA (Guardant360 CDx) during first-line AI + CDK4/6 inhibitor therapy. Patients had received AI + CDK4/6 inhibitor for ≥6 months with no investigator-assessed progression. 315 patients were randomized 1:1.
Primary endpoint was investigator-assessed PFS (RECIST v1.1): median PFS 16.0 months (95% CI, 12.7–18.2) with camizestrant vs 9.2 months (95% CI, 7.2–9.5) with AI (HR 0.44, 95% CI, 0.31–0.60; p<0.00001). OS data were not mature at the time of the PFS analysis.
Safety and dosing highlights
Labeling includes a boxed warning for arrhythmia due to QTc prolongation with concomitant QTc-prolonging drugs, and warnings/precautions for bradycardia and embryo-fetal toxicity. Recommended camizestrant dose: 75 mg orally once daily, with or without food, until progression or unacceptable toxicity, given with a CDK4/6 inhibitor.
Accelerated approval was based on PFS measured from ESR1 mutation detection; continued approval may be contingent on confirmatory trial(s).