FDA Grants Accelerated Approval to a New Treatment in Advanced Breast Cancer: Etcamah (camizestrant)
The FDA has granted accelerated approval to camizestrant in HR-positive/HER2-negative advanced breast cancer. It is the first FDA approval based on a resistance mutation detected in blood alone, before disease progression becomes visible on imaging; progression-free survival rose from 9.2 to 16 months.
4 September 2026 — The U.S. Food and Drug Administration (FDA) announced accelerated approval of the next-generation agent Etcamah (camizestrant) for the treatment of adult patients with hormone receptor (HR) positive, HER2-negative locally advanced or metastatic breast cancer.
Developed by AstraZeneca, the drug is to be used in combination with a CDK4/6 inhibitor (abemaciclib, palbociclib or ribociclib).
A First in Oncology: Detection From Blood Before Imaging
This approval represents a historic milestone in cancer treatment. As Dr. Angelo de Claro, Director of the FDA Oncology Center of Excellence, noted, this is the first FDA approval granted on the basis of a resistance mutation detected solely in circulating tumor DNA (ctDNA — liquid biopsy), before disease progression is picked up by radiologic imaging tests (scans).
For the treatment to be given, an ESR1 mutation must be detected by an FDA-approved blood test while patients are receiving aromatase inhibitor and CDK4/6 inhibitor therapy. To identify this mutation from blood with precision, the FDA authorized the Guardant360 CDx liquid biopsy test as the companion diagnostic device.
The ESR1 Mutation and the Resistance Mechanism
ESR1 mutations are "acquired resistance" mutations: rare at the outset of the tumor (present in fewer than 5% of patients), but developing over time against aromatase inhibitors, the first-line endocrine therapy.
- At diagnosis: Seen in fewer than 5% of patients.
- When the disease progresses on standard treatment: This resistance mutation emerges in the tumors of roughly 40% of patients.
Etcamah was designed precisely to break this resistance mechanism and to give patients additional time before progression occurs.
Progression-Free Survival Extended to 16 Months
The efficacy of the drug was evaluated in a clinical trial comparing patients who continued on a standard aromatase inhibitor once an ESR1 mutation was detected with those who switched to the oral Etcamah tablet.
| Treatment Arm | Median Progression-Free Survival (PFS) |
|---|---|
| Aromatase inhibitor + CDK4/6 inhibitor (continuing standard treatment) | 9.2 months |
| Etcamah (camizestrant) + CDK4/6 inhibitor | 16 months |
According to the data, patients who switched to the oral Etcamah tablet once an ESR1 mutation was detected reached a progression-free survival of 16 months, a clear clinical benefit.
Safety and Side Effect Profile
The prescribing information for the drug contains a boxed warning — the most serious form of warning — for the risk of irregular heart rhythm (arrhythmia) when Etcamah is used together with certain other drugs.
- Risk of arrhythmia: Boxed warning when used with certain drugs.
- Bradycardia: Abnormally slow heart rate.
- Embryo-fetal toxicity: Potential harm to unborn babies.
💬 What Does Accelerated Approval Mean?
Accelerated approval is a pathway that lets a drug reach patients sooner in serious diseases, on the basis of promising early data. As a requirement of this program, confirmatory clinical trials will continue to be conducted in order to verify and describe the ultimate clinical benefit of the treatment.
Conclusion
Until now, the decision to change treatment in breast cancer depended largely on seeing progression on imaging. With this approval, that decision point moves earlier: an ESR1 mutation found in blood is considered sufficient grounds to change treatment before the tumor has grown on a scan. The gain of roughly seven months in progression-free survival shows that catching resistance early has become as decisive as the choice of treatment itself.