The FDA has granted accelerated approval to AstraZeneca’s Etcamah, an oral selective estrogen receptor degrader (SERD), for certain patients with advanced breast cancer.
The drug is approved in combination with a CDK4/6 inhibitor for adults with HR-positive, HER2-negative metastatic or locally advanced breast cancer that has developed an ESR1 mutation following an aromatase inhibitor.
ESR1 mutations are acquired resistance mutations that can develop during treatment, making breast cancer more difficult to treat. While fewer than 5% of patients have an ESR1 mutation at diagnosis, nearly 40% will develop one following treatment with an aromatase inhibitor.
“Women living with metastatic breast cancer face an uphill battle as their tumors continuously evolve to escape treatment,” 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.”
Alongside Etcamah, the FDA approved the Guardant360 CDx assay as a companion diagnostic to identify breast cancer patients who have developed ESR1 mutation.
The approval marks the first FDA approval of a cancer therapy guided by detection of a resistance mutation in circulating tumor DNA (ctDNA) before imaging shows disease progression. However, the FDA noted that additional evidence is needed to confirm clinical benefit.
The agency has required AstraZeneca to conduct additional studies to confirm Etcamah’s clinical efficacy and safety.
