AstraZeneca and Daiichi Sankyo’s Enhertu (trastuzumab deruxtecan) has been approved in the U.S. for the treatment of adult patients with unresectable or metastatic hormone receptor (HR)-positive, HER2-low (IHC 1+ or IHC 2+/ISH-) or HER2-ultralow (IHC 0 with membrane staining) breast cancer, as determined by an FDA-approved test, that has progressed on one or more endocrine therapies in the metastatic setting.

The approval was granted by the FDA after securing Priority Review and Breakthrough Therapy Designation and was based on results from the DESTINY-Breast06 Phase III trial, which were published in The New England Journal of Medicine.

Dave Fredrickson, Executive Vice President, Oncology Haematology Business Unit, AstraZeneca, 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. The approval also highlights the importance of testing metastatic breast cancer tumours for detectable staining with a standard IHC test to identify those who may be eligible for treatment with Enhertu following endocrine therapy.”

Ken Keller, Global Head of Oncology Business, and President and CEO, Daiichi Sankyo, said: “Enhertu continues to redefine the classification and treatment of HR-positive metastatic breast cancer with important new data across the spectrum of HER2 expression. Today’s approval underscores our ongoing commitment to realising the full potential of this innovative antibody drug conjugate and represents another paradigm shift in how certain breast cancers can be treated.”

Enhertu is a specifically engineered HER2-directed DXd antibody drug conjugate (ADC) discovered by Daiichi Sankyo and being jointly developed and commercialized by AstraZeneca and Daiichi Sankyo.

Enhertu is already approved in more than 70 countries, including the U.S., for 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 based on the results from the DESTINY-Breast04 trial. Regulatory applications are under review in the EU, Japan and several other countries based on the DESTINY-Breast06 results.