This is the first approval based on a resistance mutation detected before standard imaging
Key takeaways
- The U.S. Food & Drug Administration has approved Etcamah (camizestrant) for certain people with HR-positive/HER2-negative breast cancer.
- Patients taking Etcamah must also take a CDK4/6 inhibitor
- Progression-free survival on Etcamah and a CDK4/6 inhibitor was 16 months, compared to 9.2 months for an aromatase inhibitor plus CDK4/6 inhibitor.
The U.S. Food & Drug Administration (FDA) granted accelerated approval to Etcamah (camizestrant), in combination with a CDK4/6 inhibitor (abemaciclib, palbociclib, or ribociclib) for adults with hormone receptor (HR)-positive/HER2-negative, locally advanced or metastatic breast cancer with an estrogen receptor-1 (ESR1) mutation acquired during aromatase inhibitor and CDK 4/6 inhibitor therapy.
Approval was granted based on the results from the SERENA-6 phase 3 clinical trial, led by Breast Cancer Research Foundation (BCRF) researcher Dr. Nicholas Turner. It showed an estimated median progression-free survival in the Etcamah and CDK4/6 inhibitor group to be 16 months, compared to 9.2 months in the aromatase inhibitor and CDK4/6 inhibitor group. Results of the trial were most recently shared at the 2026 American Society of Clinical Oncology meeting.
Etcamah (camizestrant) is a next-generation oral selective estrogen receptor degrader (SERD) that binds tightly to estrogen receptors, causing them to breakdown. HR-positive breast cancer needs estrogen to grow, so eliminating its receptors helps stop or slow progression. The drug is usually prescribed in HR-positive breast cancers that have become resistant to frontline hormonal therapies, often due to ESR1 mutations that develop during treatment. Fewer than 5% of patients have an ESR1 mutation when they are diagnosed with HR-positive metastatic breast cancer, but after taking an aromatase inhibitor, the number rises to nearly 40%.
This is the first time a cancer therapy has been approved based on a mutation detected via circulating tumor DNA (ctDNA) testing, which measures tiny fragments of tumor DNA in the blood. It could potentially usher in a new way to see cancer earlier, on a molecular level, before it is visible on imaging.
The FDA’s accelerated approval program grants expedited approval of potentially lifesaving medications. Etcamah’s approval was based on how long patients lived without their cancer worsening but will still require additional studies to confirm overall survival i.e., long term clinical benefit.
