Tokyo, July 24, 2026
Daiichi Sankyo and AstraZeneca announced that the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP) has issued a positive opinion recommending the approval of Enhertu® (trastuzumab deruxtecan) in combination with pertuzumab as a first-line treatment for adult patients with unresectable or metastatic HER2-positive breast cancer. The recommendation is based on the Phase 3 DESTINY-Breast09 trial, where the combination demonstrated a 44% reduction in the risk of disease progression or death compared with the current standard-of-care regimen of taxane, trastuzumab and pertuzumab (THP). If approved by the European Commission, the combination would become the first new first-line treatment option in the European Union in more than a decade for patients with HER2-positive metastatic breast cancer, potentially redefining the treatment landscape for this aggressive disease.
DESTINY-Breast09 Shows Significant Improvement in Progression-Free Survival
The CHMP recommendation is supported by compelling results from the global Phase 3 DESTINY-Breast09 trial, which enrolled patients with previously untreated HER2-positive metastatic breast cancer. Treatment with Enhertu plus pertuzumab achieved a median progression-free survival (PFS) of 40.7 months, compared with 26.9 months for patients receiving the current THP standard of care, representing an improvement of more than 13 months. The combination also demonstrated an 85.1% confirmed objective response rate, including 15.1% complete responses, compared with 78.6% for THP. Additionally, the median duration of response exceeded three years (39.2 months), further highlighting the durability of clinical benefit. The progression-free survival advantage remained consistent across key patient subgroups, including hormone receptor status, recurrent versus de novo metastatic disease, and PIK3CA mutation status, reinforcing the therapy’s broad clinical potential.
Safety Profile Remains Consistent with Established Experience
According to Daiichi Sankyo and AstraZeneca, the safety profile of Enhertu plus pertuzumab remained consistent with previously established safety data, with no new safety concerns identified during the DESTINY-Breast09 study. The most common Grade 3 or higher treatment-related adverse events included neutropenia, hypokalemia, and anemia. Interstitial lung disease (ILD) or pneumonitis occurred in 12.1% of treated patients, with the majority of cases classified as Grade 1 or Grade 2, while Grade 5 ILD events occurred in only 0.5% of participants. Investigators noted that the benefit-risk profile supports moving Enhertu into earlier treatment settings, where initiating highly effective HER2-targeted therapy may significantly improve long-term patient outcomes and delay disease progression.
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Potential to Redefine First-Line HER2-Positive Breast Cancer Treatment
HER2-positive metastatic breast cancer accounts for approximately 15% to 20% of metastatic breast cancer cases and remains an aggressive disease despite advances in targeted therapies. Current first-line treatment with THP has remained the standard for more than 10 years, yet many patients experience disease progression within two years and a substantial proportion never receive subsequent therapy. If the European Commission grants final approval, Enhertu plus pertuzumab would establish a new first-line treatment standard across the European Union while expanding the growing global role of Enhertu, which is already approved in multiple countries for several HER2-positive and HER2-low cancers, including breast, lung, gastric, and solid tumors. The approval would further strengthen the long-standing oncology collaboration between Daiichi Sankyo and AstraZeneca, advancing the use of antibody-drug conjugate (ADC) technology to improve outcomes for patients with difficult-to-treat cancers.
Source: Daiichi Sankyo press release
