WASHINGTON, D.C. (WDNews) – The U.S. Food and Drug Administration has granted accelerated approval to a new treatment for certain patients with advanced or metastatic breast cancer.
According to the FDA, Etcamah, also known as camizestrant, was approved in combination with a CDK4/6 inhibitor for adults with hormone receptor-positive, HER2-negative locally advanced or metastatic breast cancer whose tumors develop a specific ESR1 mutation during treatment.
The treatment is intended for patients whose ESR1 mutation is detected while they are receiving an aromatase inhibitor and a CDK4/6 inhibitor. An FDA-authorized test must be used to identify the mutation.
ESR1 mutations can develop as breast cancer adapts to treatment and becomes resistant to aromatase inhibitors, a common type of endocrine therapy.
According to the FDA, fewer than 5% of patients have an ESR1 mutation when HR-positive metastatic breast cancer is first diagnosed. However, nearly 40% may have the mutation after their cancer progresses while being treated with an aromatase inhibitor.
“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,” Acting FDA Commissioner Kyle Diamantas said. “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.”
The FDA said the approval represents the first time it has approved a cancer treatment based on detecting a resistance mutation in circulating tumor DNA before imaging shows that the cancer is progressing.
Circulating tumor DNA, or ctDNA, consists of small pieces of DNA released by tumors into the bloodstream. Blood testing can allow doctors to detect certain molecular changes before they become apparent on imaging tests.
“This marks the first FDA approval of a cancer therapy guided by the detection of a resistance mutation in circulating tumor DNA (ctDNA) before imaging tests show that the disease is progressing,” said Dr. Angelo de Claro, director of the FDA’s Oncology Center of Excellence. “But additional evidence is needed to confirm clinical benefit.”
The FDA also authorized the Guardant360 CDx assay as a companion diagnostic test to identify breast cancer patients with ESR1 mutations who may be eligible for treatment with camizestrant.
In a clinical trial, patients who switched to Etcamah, an oral tablet, combined with a CDK4/6 inhibitor had an estimated median progression-free survival of 16 months. Patients who continued an aromatase inhibitor with a CDK4/6 inhibitor had an estimated median progression-free survival of 9.2 months.
Progression-free survival measures how long patients live without their cancer worsening.
The treatment was granted accelerated approval, a pathway that allows the FDA to approve treatments for serious conditions earlier based on evidence suggesting a potential clinical benefit.
However, the FDA said it has not yet been confirmed whether beginning the new treatment when the mutation is detected — rather than waiting until the disease is confirmed to have progressed — provides a clinically meaningful benefit. Confirmatory studies will be required.
Etcamah’s prescribing information includes a boxed warning about the risk of irregular heart rhythm when it is taken with certain other medications. The FDA also lists warnings for an abnormally slow heart rate and possible harm to an unborn baby.
The accelerated approval was granted to AstraZeneca.
