European Commission Approves AstraZeneca's Etcamah for ER-Positive Breast Cancer with ESR1 Mutations

Jul 23, 2026

The European Commission has approved AstraZeneca's Etcamah (camizestrant) in combination with a CDK4/6 inhibitor for adult patients with ER-positive, HER2-negative advanced breast cancer who develop ESR1 mutations. Based on the Phase III SERENA-6 trial, this regimen reduces the risk of disease progression or death by 56% compared to standard-of-care aromatase inhibitors. The approval marks a shift toward ctDNA-guided, pre-progression treatment switching to address emerging endocrine resistance.

Etcamah EU regulatory approval

▪Etcamah is also approved in Japan, the United Arab Emirates, and Saudi Arabia, while regulatory applications remain under review in other countries, including the United States.
▪The European Commission approved AstraZeneca's Etcamah (camizestrant) in combination with a CDK4/6 inhibitor for adults with ER-positive, HER2-negative locally advanced or metastatic breast cancer with an ESR1 mutation and no disease progression during first-line endocrine therapy.
▪Etcamah is approved in the European Union for use in combination with any of the widely approved CDK4/6 inhibitors, including palbociclib, ribociclib, or abemaciclib.

SERENA-6 trial efficacy results

▪The SERENA-6 trial demonstrated a median progression-free survival of 16.0 months for the Etcamah combination compared to 9.2 months for the standard-of-care aromatase inhibitor combination.
▪A pre-planned analysis of the SERENA-6 trial showed a statistically significant second progression-free survival benefit of 25.7 months for the Etcamah combination versus 19.1 months for the comparator.
▪In the pivotal Phase III SERENA-6 trial, the Etcamah combination reduced the risk of disease progression or death by 56% compared to standard-of-care treatment with an aromatase inhibitor and a CDK4/6 inhibitor.

ctDNA-guided treatment switching

▪In the SERENA-6 trial, patients were monitored via blood-based circulating tumor DNA tests every two to three months to identify early signs of endocrine resistance through the emergence of ESR1 mutations.
▪Data presented at the American Society of Clinical Oncology meeting in June showed that patients switching to Etcamah had a median 99% reduction in ctDNA after eight weeks, with half achieving total ctDNA clearance.
▪The Phase III SERENA-6 trial is the first global registrational study to use a circulating tumor DNA-guided approach to detect endocrine resistance and switch therapy before radiographic disease progression.

ESR1 mutation endocrine resistance

▪Mutations in the ESR1 gene are a key driver of endocrine resistance in hormone receptor-positive breast cancer, emerging during treatment and becoming more prevalent as the disease progresses.
▪Approximately 30% of patients with endocrine-sensitive hormone receptor-positive breast cancer develop ESR1 mutations during first-line treatment before disease progression.

CDK4/6 inhibitor combination therapy

▪The safety profile of Etcamah in combination with palbociclib, ribociclib, or abemaciclib in the SERENA-6 trial was consistent with the known safety profile of each individual medicine, with very low discontinuation rates.
▪The recommended dose of Etcamah, a potent, next-generation oral selective estrogen receptor degrader and complete estrogen receptor antagonist, is 75mg administered orally once daily.