FDA approves AstraZeneca breast cancer drug

The FDA has granted accelerated approval to AstraZeneca drug Etcamah for certain adults with advanced breast cancer carrying an ESR1 mutation.

Etcamah, also known as camizestrant, was approved in combination with a CDK4/6 inhibitor, either abemaciclib, palbociclib or ribociclib.

The treatment is for adults with hormone receptor-positive, HER2-negative, locally advanced or metastatic breast cancer when an estrogen receptor-1 (ESR1) mutation is detected during aromatase inhibitor and CDK4/6 inhibitor therapy using an FDA-authorised test.

ESR1 mutations are acquired resistance mutations that tumours may develop during treatment with aromatase inhibitors, a type of endocrine therapy commonly used as a front-line treatment for locally advanced or metastatic breast cancer.

Fewer than 5 per cent of patients have the mutation when HR-positive metastatic breast cancer is diagnosed, according to the FDA. After disease progression on an aromatase inhibitor, nearly 40 per cent have the mutation.

Acting FDA commissioner Kyle Diamantas said: “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.

“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 accelerated approval programme allows earlier approval of drugs that treat serious conditions and fill an unmet medical need based on surrogate or intermediate endpoints.

For Etcamah, approval was based on how long patients lived without their disease worsening, measured from when the resistance mutation was first detected in their blood.

The FDA said it has not yet been confirmed whether intervening when the mutation is detected, rather than waiting until disease progression is confirmed, results in a clinically meaningful benefit. Confirmatory studies are therefore required to verify and describe clinical benefit.

Angelo de Claro, director of the FDA’s Oncology Center of Excellence, said: “I commend both the FDA and the sponsor for their commitment to advancing cancer care and securing this accelerated approval.

“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.

“But additional evidence is needed to confirm clinical benefit.”

Circulating tumour DNA, or ctDNA, consists of small pieces of tumour DNA released into the blood and can allow earlier molecular detection of resistance mutations.

The FDA also authorised the Guardant360 CDx assay as a companion diagnostic to identify patients with breast cancer who have ESR1 mutations for treatment with camizestrant.

Efficacy was assessed in a clinical trial comparing a switch to Etcamah plus a CDK4/6 inhibitor with continued treatment using an aromatase inhibitor plus a CDK4/6 inhibitor.

Estimated median progression-free survival was 16 months in the Etcamah group, compared with 9.2 months in the aromatase inhibitor group.

Etcamah’s prescribing information includes a boxed warning about the risk of irregular heart rhythm when taken with certain other medicines. It also includes warnings about an abnormally slow heart rate and potential harm to an unborn baby.

The FDA convened its Oncologic Drugs Advisory Committee for the application on 30 April 2026.