The US Food and Drug Administration (FDA) granted accelerated approval to AstraZeneca’s Etcamah, also known as camizestrant, on 4 September 2026 for adults with advanced or metastatic hormone receptor-positive, HER2-negative breast cancer with an ESR1 mutation. The drug was approved as a 75 mg oral daily therapy in combination with CDK4/6 inhibitors abemaciclib, palbociclib, or ribociclib.
Breast Cancer and Biomarker-Based Treatment
Hormone receptor-positive breast cancer is a subtype that depends on oestrogen or progesterone signalling for tumour growth. HER2-negative breast cancer lacks overexpression or amplification of the human epidermal growth factor receptor 2 gene. ESR1 is the gene that encodes the oestrogen receptor, and mutations in this gene are linked with resistance to aromatase inhibitors.
Companion Diagnostic and ctDNA
The FDA also approved Guardant Health’s Guardant360 CDx as a companion diagnostic for detecting qualifying ESR1 mutations. The assay uses circulating tumour DNA, or ctDNA, which refers to fragments of tumour-derived DNA found in blood plasma. ctDNA testing is a form of liquid biopsy used in oncology for molecular profiling.
Clinical Trial Basis and Regulatory Context
The approval was based on data from the 315-patient Phase III SERENA-6 trial. The trial found that the Etcamah combination reduced the risk of disease progression or death by 56% compared with standard aromatase inhibitor therapy, and the median progression-free survival was 16.0 months versus 9.2 months in the control group. The Oncologic Drugs Advisory Committee had voted 6-3 in April 2026 against the early-switching strategy before the FDA decision.
Important Facts for Exams
- Accelerated approval is a US FDA pathway used for serious conditions and unmet medical needs.
- CDK4/6 inhibitors include abemaciclib, palbociclib, and ribociclib.
- Guardant360 CDx is a companion diagnostic used with a specific therapy or drug class.
- Progression-free survival is a common endpoint in oncology trials and measures the time before disease progression or death.
AstraZeneca and 2026 Approvals
AstraZeneca’s Oncology Business Unit Executive Vice President Dave Fredrickson stated that Etcamah was the company’s tenth FDA drug approval in 2026 and its fourth approval for breast cancer. The approval date was 4 September 2026, and the therapy was authorised in the United States.
