AstraZeneca (AZN) said Thursday the European Commission approved its experimental drug, Etcamah, in combination with a CDK4/6 inhibitor, for adults with a type of breast cancer harboring an ESR1 mutation that emerges during first-line endocrine therapy, after the Phase 3 SERENA-6 trial met its primary endpoint.

The company said the trial met its primary goal by reducing the risk of disease progression or death by 56% compared with an aromatase inhibitor plus a CDK4/6 inhibitor.

Patients receiving the Etcamah combination lived a median of 16 months without their disease worsening, compared with 9.2 months for patients who remained on the comparator regimen, the company said.

AstraZeneca said the trial also showed patients lived longer before their disease worsened a second time, while overall survival data remain immature.

The company said it will continue evaluating overall survival in the ongoing SERENA-6 trial.