AstraZeneca (AZ) and Daiichi Sankyo’s Enhertu (trastuzumab deruxtecan) has been approved by the US Food and Drug Administration (FDA) to treat a new subset of breast cancer patients.
The antibody drug conjugate (ADC) has been authorised for use in adults with unresectable or metastatic hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-low or HER2-ultralow breast cancer that has progressed on one or more endocrine therapies in the metastatic setting.
The FDA’s decision, which makes Enhertu the first HER2-directed therapy approved for this patient population, was supported by positive results from the late-stage DESTINY-Breast06 trial.
Enhertu was associated with a 36% reduction in the risk of disease progression or death compared to chemotherapy in the overall study population of patients with chemotherapy-naïve HER2-low or HER2-ultralow metastatic breast cancer.
A median progression-free survival of 13.2 months was seen in Enhertu-treated patients compared to 8.1 months in those randomised to receive chemotherapy, and the confirmed objective response rate in the overall trial population was 62.6% for Enhertu and 34.4% for chemotherapy.
Additionally, in an exploratory analysis of patients with HER2-ultralow expression, results were found to be consistent between patients with HER2-low and HER2-ultralow expression.
More than 300,000 people are diagnosed with breast cancer every year in the US, and HR-positive, HER2-negative disease accounts for approximately 70% of all cases.
Endocrine therapies are typically given in the early lines of treatment for HR-positive metastatic breast cancer. However, further efficacy is often limited after initial treatment, and subsequent chemotherapy is associated with poor outcomes.
Enhertu is already approved in the US to treat patients with HER2-low metastatic breast cancer who have received a prior systemic therapy in the metastatic setting or developed disease recurrence during or within six months of completing adjuvant chemotherapy.
Commenting on the latest authorisation for the drug, Dave Fredrickson, executive vice president, oncology haematology business unit, AZ, said: “Building on the practice-changing previous approvals for Enhertu, this new approval brings this important medicine to an earlier treatment setting and a broader patient population with HER2-expressing metastatic breast cancer.”
Ken Keller, global head of oncology business, and president and chief executive officer, Daiichi Sankyo, added: “Enhertu continues to redefine the classification and treatment of HR-positive metastatic breast cancer with important new data across the spectrum of HER2 expression.”