WILMINGTON, DE — Positive interim results from the Phase III DESTINY-Breast09 trial revealed that ENHERTU® (fam-trastuzumab deruxtecan-nxki), combined with pertuzumab, delivered a highly statistically significant and clinically meaningful improvement in progression-free survival (PFS) as a first-line treatment for HER2-positive metastatic breast cancer. This combination outperformed the standard regimen of a taxane, trastuzumab, and pertuzumab (THP), offering new hope for patients facing aggressive disease.
The trial demonstrated PFS benefits across all pre-specified patient subgroups. While overall survival (OS), a key secondary endpoint, was not yet mature, initial data indicated an early trend favoring the ENHERTU and pertuzumab combination over THP. The study’s second arm, evaluating ENHERTU monotherapy versus THP, remains blinded and will progress to final PFS analysis.
HER2-positive metastatic breast cancer, affecting 15-20% of metastatic breast cancer patients, has historically shown poor outcomes despite advances in HER2-targeted therapies. Many patients experience disease progression within two years of first-line treatment, and one-third do not receive further therapy due to rapid progression or death.
Susan Galbraith, Executive Vice President of Oncology Hematology R&D at AstraZeneca, commented on the milestone, stating, “This is the first trial in more than a decade to demonstrate superior efficacy across a broad HER2-positive metastatic breast cancer patient population compared to the current 1st-line standard of care. This is a significant milestone for patients and sets the foundation for ENHERTU in combination with pertuzumab as an important treatment option in the first-line HER2-positive setting.”
Ken Takeshita, Global Head of R&D at Daiichi Sankyo, added, “The results from DESTINY-Breast09 reinforce the importance of effectively targeting HER2 to achieve durable disease control early in the treatment of HER2-positive metastatic breast cancer. Building on the positive results seen with ENHERTU in the second-line setting, these new findings suggest that starting treatment with ENHERTU in combination with pertuzumab at the time of metastatic diagnosis delays disease progression, postponing the time until additional treatment may be needed.”
The safety profile of ENHERTU combined with pertuzumab was consistent with the known profiles of the individual therapies, underscoring its potential as a safe and effective first-line option.
ENHERTU, a HER2-directed DXd antibody drug conjugate co-developed and commercialized by AstraZeneca and Daiichi Sankyo, is already approved in more than 75 countries as a second-line HER2-positive breast cancer treatment based on earlier trial results.
Full data from DESTINY-Breast09 will be presented at an upcoming medical meeting and shared with regulatory authorities. If approved for first-line use, ENHERTU’s combination with pertuzumab could redefine the standard of care for HER2-positive metastatic breast cancer, offering patients a longer progression-free period and improved outcomes.
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