On Sept. 4, 2026, the U.S. Food and Drug Administration (FDA) announced they have expanded treatment options for adult patients with advanced breast cancer, reflecting the FDA’s commitment to advancing medical innovation and getting new treatments to patients who need them.

FDA granted accelerated approval to AstraZeneca’s Etcamah (camizestrant) in combination with a CDK4/6 inhibitor (abemaciclib, palbociclib, or ribociclib) for the treatment of adult patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, locally advanced or metastatic breast cancer upon detection of estrogen receptor-1 (ESR1) mutation during aromatase inhibitor and CDK 4/6 inhibitor therapy, based on an FDA-authorized test.

ESR1 mutations are acquired resistance mutations that a tumor may develop during treatment with an aromatase inhibitor, a type of endocrine therapy that is a common front-line treatment for locally advanced or metastatic breast cancer. At the diagnosis of HR-positive metastatic breast cancer, fewer than 5 percent of patients will have this tumor mutation. After disease progression on an aromatase inhibitor, nearly 40 percent of patients will have this tumor mutation.

The accelerated approval program allows for earlier approval of drugs that treat serious conditions, and fill an unmet medical need based on surrogate or intermediate endpoints. In this case, accelerated approval of Etcamah was granted based on how long patients lived without their disease worsening, measured from the point when the resistance mutation was first detected in the blood. Since it is not yet confirmed whether intervening at this point, rather than at the time of confirmed disease progression, translates into a clinically meaningful benefit, the FDA has required confirmatory studies to verify and describe clinical benefit.

ctDNA is made up of tiny pieces of tumor DNA released into the blood, which can allow for earlier molecular detection of resistance mutations.

To ensure precise patient matching, the FDA also authorized the Guardant360 CDx assay as a companion diagnostic device to identify patients with breast cancer with ESR1 mutations for treatment with camizestrant.

Efficacy was evaluated in a clinical trial to assess switching to Etcamah, an oral tablet, in combination with a CDK4/6 inhibitor versus continuing an aromatase inhibitor in combination with a CDK4/6 inhibitor. Estimated median progression-free survival was 16 months in the Etcamah and CDK4/6 inhibitor arm and 9.2 months in the aromatase inhibitor and CDK4/6 inhibitor arm.