Etcamah (camizestrant): FDA approval, pivotal trial and safety
Approved
Type
New molecular entity · Oral
FDA-approved use
To treat hormone receptor-positive, human epidermal growth factor receptor 2-negative, locally advanced or metastatic breast cancer upon detection of ESR1 mutation during aromatase inhibitor and CDK4/6 inhibitor therapyWording from FDA's list of novel approvals.
FDA review
Standard review
Company
AstraZeneca
Application
NDA 220359
Specialty
Oncology
Boxed warning: Arrhythmia risk with concomitant use of QTc interval prolonging drugs
At a glance
Etcamah (camizestrant) is an oral estrogen receptor antagonist approved under accelerated approval, with a CDK4/6 inhibitor, for HR-positive, HER2-negative locally advanced or metastatic breast cancer when an ESR1 mutation is detected during aromatase inhibitor plus CDK4/6 inhibitor therapy. In SERENA-6, switching to it cut the risk of progression or death versus continuing the aromatase inhibitor (hazard ratio 0.44; median PFS 16.0 vs 9.2 months). It carries a boxed warning for arrhythmia risk with QTc-prolonging drugs.
What it is and how it works
Camizestrant binds the ligand binding domain of ER alpha and blocks its activity, including the mutated ESR1 form. It also drives proteasome-dependent degradation of the receptor and does not act as an agonist. Aromatase inhibitors lower estrogen production and do not overcome ESR1-mutant receptor signaling. Here the drug is used as a switch, guided by ctDNA testing, while the CDK4/6 inhibitor continues and before clinical progression.
Randomized, double-blind, placebo-controlled, multicenter phase III trial with ctDNA-guided switching. ESR1 testing was done every 2 to 3 months, and randomization (1:1) occurred when a mutation was found without progression.
Patients
315 patients with ER-positive, HER2-negative advanced breast cancer and an emerging ESR1 mutation, after at least 6 months of first-line aromatase inhibitor plus CDK4/6 inhibitor. 3256 patients were tested. Median age 61 years; 99% female.
Compared with
Continued aromatase inhibitor (anastrozole or letrozole) plus the same CDK4/6 inhibitor, with placebo in place of camizestrant.
Primary endpoint
Investigator-assessed progression-free survival by RECIST v1.1.
Result
Median PFS was 16.0 months (95% CI 12.7 to 18.2) with camizestrant versus 9.2 months (95% CI 7.2 to 9.5) with the aromatase inhibitor. Hazard ratio 0.44 (95% CI 0.31 to 0.60); P<0.0001. Events occurred in 71 of 157 and 100 of 158 patients.
Other results
Median time to deterioration in patient-reported global health status and quality of life was 21.0 vs 6.4 months (hazard ratio 0.54; 95% CI 0.34 to 0.84). Overall survival data were immature at analysis (12% maturity).
Safety in the trial
Serious adverse reactions occurred in 10% and fatal adverse reactions in 1.3%. Discontinuation for adverse events was 1.3% with camizestrant and 1.9% with the aromatase inhibitor. QTc prolongation occurred in 2.6%. Visual effect adverse events occurred in 31.6% vs 16.1%, 90% grade 1, none leading to discontinuation, with no change in visual acuity or ocular structure.
How does Etcamah (camizestrant) compare with the alternatives (Aromatase inhibitor plus CDK4/6 inhibitor (continued), Fulvestrant, Elacestrant) for hormone receptor-positive, human epidermal growth factor receptor 2-negative, locally advanced or metastatic breast cancer upon detection of ESR1 mutation during aromatase inhibitor and CDK4/6 inhibitor therapy? Summarize head-to-head and indirect evidence, efficacy, safety and where each fits, with citations.
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Safety signals
The boxed warning covers torsades de pointes, other ventricular arrhythmias, and sudden death when the drug is combined with ribociclib or other QTc-prolonging drugs. Avoid other QTc-prolonging drugs; if unavoidable, monitor the QTc more often. Obtain an ECG before starting, and monitor heart rate and QTc and correct electrolytes during treatment. Bradycardia is a separate warning, with closer heart rate monitoring in the first 30 days. The drug can cause fetal harm, so effective contraception is advised. Common adverse reactions were low blood counts, visual disturbances, and fatigue. Visual effects were mostly grade 1 and reversible.
What it competes with
First-line treatment for HR-positive, HER2-negative advanced breast cancer is usually an aromatase inhibitor with a CDK4/6 inhibitor. After progression, options include other endocrine agents, targeted combinations, and chemotherapy.
Aromatase inhibitor plus CDK4/6 inhibitor (continued)The standard first-line regimen and the comparator in the pivotal trial. Continuing it leaves the ESR1-mutant clone without targeted endocrine therapy.
FulvestrantAn injectable estrogen receptor degrader used after progression on endocrine therapy, often with a CDK4/6 inhibitor.
ElacestrantAn oral estrogen receptor antagonist approved for ESR1-mutated disease after prior endocrine therapy.
ChemotherapyUsed when endocrine options are exhausted or disease is rapidly progressing. Delaying it was a rationale for the switching strategy.
Bottom line for clinicians
This drug is for patients on first-line aromatase inhibitor plus CDK4/6 inhibitor without progression who have an ESR1 mutation found on an FDA-authorized ctDNA test. Approval is accelerated and rests on PFS, and overall survival data were immature, so clinical benefit still needs confirmation. Weigh the arrhythmia and bradycardia risks, especially with ribociclib, and plan ECG and electrolyte monitoring.
Dosing, contraindications and full warnings are in the prescribing information.
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Last updated October 27, 2026 by 2 Minute Medicine.
For healthcare professionals. A summary of public FDA documents and published trials, not medical advice. Check the full prescribing information before prescribing.
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