WILMINGTON, DE — The Phase III DESTINY-Breast09 clinical trial has delivered groundbreaking results, demonstrating that ENHERTU® (fam-trastuzumab deruxtecan-nxki) plus pertuzumab significantly improves progression-free survival (PFS) for patients with HER2-positive metastatic breast cancer when used as a first-line treatment. The findings were presented during a late-breaking session at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, IL.
Compared to the standard treatment of a taxane, trastuzumab, and pertuzumab (THP), ENHERTU plus pertuzumab reduced the risk of disease progression or death by 44%, achieving a median PFS of 40.7 months versus 26.9 months as assessed by blinded independent central review. These results mark the first improvement in first-line care for this broad patient population in over a decade, according to AstraZeneca and Daiichi Sankyo, the developers of ENHERTU.
Dr. Sara Tolaney, Chief of the Division of Breast Oncology at Dana-Farber Cancer Institute and principal investigator in the trial, noted, “Patients with HER2-positive metastatic breast cancer often experience disease progression around two years after initiating standard-of-care first-line treatment. With a median progression-free survival of more than three years, the DESTINY-Breast09 results show trastuzumab deruxtecan combined with pertuzumab has the potential to become a new first-line standard of care for these patients.”
The trial reported an impressive confirmed objective response rate (ORR) of 85.1% for ENHERTU plus pertuzumab, compared to 78.6% for THP. Additionally, the new therapy demonstrated a longer median duration of response (39.2 months) compared to the standard treatment (26.4 months).
Safety data from the trial were consistent with the known profiles of both ENHERTU and pertuzumab, with no new concerns identified. Interstitial lung disease (ILD) occurred in 12.1% of cases, with the majority of events being Grades 1 or 2. Notably, there were two Grade 5 ILD events reported.
Susan Galbraith, Executive Vice President of Oncology Haematology R&D at AstraZeneca, emphasized the study’s importance, stating, “Bringing ENHERTU earlier in the treatment of HER2-positive metastatic breast cancer may represent an important advancement for patients. The DESTINY-Breast09 trial showed the combination of ENHERTU and pertuzumab in the first-line setting substantially increased the amount of time before a patient’s cancer progressed compared to standard of care and nearly doubled the number of patients showing no signs of disease on imaging.”
Ken Takeshita, Global Head of R&D at Daiichi Sankyo, added, “DESTINY-Breast09 shows that initiating treatment with ENHERTU in combination with pertuzumab at the time of metastatic diagnosis can delay disease progression.”
ENHERTU, a HER2-directed DXd antibody drug conjugate (ADC), is jointly developed and commercialized by AstraZeneca and Daiichi Sankyo. Approved in over 80 countries for second-line treatment, it continues to demonstrate its potential to reshape cancer therapies, offering hope to countless patients worldwide.
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