The U.S. Food and Drug Administration (FDA) has expanded treatment options for adults with advanced breast cancer through the accelerated approval of Etcamah (camizestrant). The decision reflects the FDA’s continued focus on advancing medical innovation and making new treatments available to patients who need them. Etcamah has been approved for use with a CDK4/6 inhibitor (abemaciclib, palbociclib, or ribociclib) for adult patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, locally advanced or metastatic breast cancer. The treatment applies when an estrogen receptor-1 (ESR1) mutation is detected during aromatase inhibitor and CDK 4/6 inhibitor therapy based on an FDA-authorized test.
ESR1 mutations are resistance mutations that tumors may acquire while a patient is receiving an aromatase inhibitor, a type of endocrine therapy commonly used as a front-line treatment for locally advanced or metastatic breast cancer. At the time HR-positive metastatic breast cancer is diagnosed, fewer than 5 percent of patients have this tumor mutation. Following disease progression while receiving an aromatase inhibitor, however, nearly 40 percent of patients will have the mutation.
“Women living with metastatic breast cancer face an uphill battle as their tumors continuously evolve to escape treatment. We owe them every weapon in our arsenal.” said Acting FDA Commissioner Kyle Diamantas, J.D.
“Today’s approval delivers a win to these patients by granting them a targeted therapy designed specifically to overcome resistance, giving them more time before their disease progresses,” he added.
Accelerated Approval Requires Confirmatory Evidence
Etcamah received accelerated approval based on progression-free survival, measuring how long patients remained without worsening disease from the point at which the resistance mutation was first identified in the blood. The FDA’s accelerated approval program permits earlier authorization of medicines intended for serious conditions that address an unmet medical need when approval is supported by surrogate or intermediate endpoints. Because it remains uncertain whether treating patients at the point of resistance mutation detection, instead of waiting for confirmed disease progression, provides a clinically meaningful benefit, the FDA has required confirmatory studies to establish and further describe the clinical benefit.
“I commend both the FDA and the sponsor for their commitment to advancing cancer care and securing this accelerated approval,” said Angelo de Claro, M.D., director of the FDA’s Oncology Center of Excellence.
ctDNA consists of small pieces of tumor DNA that are released into the bloodstream, providing an opportunity to detect resistance mutations at an earlier molecular stage. To support the identification of appropriate patients with breast cancer, the FDA also authorized the Guardant360 CDx assay as a companion diagnostic device for identifying patients with ESR1 mutations who may receive camizestrant.
Clinical Trial Shows Longer Progression-Free Survival
The efficacy of Etcamah was assessed in a clinical trial comparing a switch to the oral tablet in combination with a CDK4/6 inhibitor against continued treatment with an aromatase inhibitor alongside a CDK4/6 inhibitor. The estimated median progression-free survival reached 16 months among patients receiving Etcamah and a CDK4/6 inhibitor. By comparison, the estimated median progression-free survival was 9.2 months in the aromatase inhibitor and CDK4/6 inhibitor arm. The results form the clinical basis for the expanded breast cancer treatment option under the FDA’s accelerated approval pathway.
