AstraZeneca PLC (LSE:AZN) reported positive high-level results from its pivotal DESTINY-Breast04 Phase III trial which showed an improved survival rate for patients treated with Enhertu (trastuzumab deruxtecan).
In the trial, Enhertu demonstrated a statistically significant and clinically meaningful improvement in both progression-free survival (PFS) and overall survival (OS) in patients with HER2-low unresectable and/or metastatic breast cancer regardless of hormone receptor (HR) status versus treatment with chemotherapy, the drug giant said in a statement.
Enhertu is a HER2-directed antibody drug conjugate (ADC) being jointly developed by AstraZeneca and Daiichi Sankyo.
HER2 testing is well established to determine an appropriate treatment strategy in metastatic breast cancer. Targeting the lower range of HER2 expression may offer another approach to delay disease progression and extend survival in patients with metastatic breast cancer, AstraZeneca said.
Currently, chemotherapy is the only treatment option both for patients with HR-positive tumours following progression on endocrine (hormone) therapy, and for those who are HR-negative.
DESTINY-Breast04 met its primary endpoint, where Enhertu demonstrated superior PFS in previously treated patients with HR-positive HER2-low metastatic breast cancer compared to the standard-of-care chemotherapy.
The trial met the key secondary endpoint of PFS in patients with HER2-low metastatic breast cancer regardless of HR status (HR-positive or HR-negative). It also met the key secondary endpoints of OS in patients with HR-positive disease and in patients regardless of HR status at interim analysis.
"Today's historic news from DESTINY-Breast04 could reshape how breast cancer is classified and treated,” Susan Galbraith, executive vice president, Oncology R&D, AstraZeneca said.
“A HER2-directed therapy has never before shown a benefit in patients with HER2-low metastatic breast cancer. These results for Enhertu are a huge step forward and could potentially expand our ability to target the full spectrum of HER2 expression, validating the need to change the way we categorise and treat breast cancer."
READ: AstraZeneca's Enhertu granted Priority Review for breast cancer in US
Enhertu (5.4mg/kg) is approved in more than 40 countries for the treatment of adult patients with unresectable or metastatic HER2-positive breast cancer who have received two or more prior anti-HER2-based regimens based on the results from the DESTINY-Breast01 trial.
The drug is being further assessed in a comprehensive clinical development programme evaluating efficacy and safety across multiple HER2-targetable cancers, including breast, gastric, lung and colorectal cancers.