CAMBRIDGE, UK, Sept. 1, 2026
AstraZeneca and Daiichi Sankyo announced that the European Commission has approved Enhertu (trastuzumab deruxtecan) in combination with pertuzumab for the first-line treatment of adults with HER2-positive, unresectable or metastatic breast cancer. The approval introduces the first new first-line treatment regimen for this patient population in more than a decade and is based on results from the Phase III DESTINY-Breast09 trial, which demonstrated a significant improvement in progression-free survival compared with the established treatment combination of trastuzumab and a taxane.
DESTINY-Breast09 Demonstrates Longer Disease Control
The European approval was supported by results from the randomized, multicenter, open-label DESTINY-Breast09 Phase III trial, which evaluated Enhertu alone and Enhertu plus pertuzumab against trastuzumab plus pertuzumab and a taxane in patients with previously untreated HER2-positive metastatic or unresectable breast cancer. The study investigated whether the antibody-drug conjugate-based regimens could provide greater disease control in the first-line setting. The Enhertu plus pertuzumab combination significantly improved progression-free survival, meeting the primary endpoint of the trial. Patients receiving the combination achieved a median progression-free survival of approximately 40.7 months, compared with approximately 26.9 months for patients treated with trastuzumab, pertuzumab and a taxane. These results represent a substantial extension in the time before disease progression and highlight the potential of the new regimen to change the treatment approach for HER2-positive metastatic breast cancer. The trial also showed encouraging overall survival findings. At the time of the reported analysis, the Enhertu-containing treatment demonstrated a favorable trend in overall survival compared with the control regimen. The companies said overall survival data were not yet mature at the primary analysis, meaning continued follow-up is needed to establish the full survival benefit.
New First-Line Option for HER2-Positive Disease
HER2-positive metastatic breast cancer is characterized by high levels of the HER2 protein, which can promote cancer-cell growth and progression. Although targeted therapies have substantially improved outcomes for patients with HER2-positive disease, metastatic breast cancer remains incurable and continued treatment innovation is needed. Enhertu is an antibody-drug conjugate (ADC) designed to deliver a topoisomerase I inhibitor payload directly to HER2-expressing cancer cells. Pertuzumab is a HER2-targeted monoclonal antibody that binds to a different region of the HER2 receptor. Combining the two medicines is intended to provide complementary mechanisms of HER2 targeting while using Enhertu’s ADC technology to deliver its cytotoxic payload. The EU approval allows the regimen to be used as a first-line treatment, giving physicians an additional treatment option for eligible adults with HER2-positive metastatic breast cancer. The companies described the regulatory decision as an important advance for patients who require effective treatment from the beginning of their metastatic disease journey.
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Approval Expands Enhertu’s Role in Breast Cancer
The decision further expands the role of Enhertu in the treatment of HER2-positive breast cancer and builds on the medicine’s established clinical development program across multiple stages and types of HER2-expressing cancers. The latest approval reflects growing evidence supporting antibody-drug conjugates as an important class of targeted cancer therapies. The safety profile observed with the Enhertu plus pertuzumab combination in DESTINY-Breast09 was generally consistent with the known safety profiles of the individual medicines. Important adverse reactions associated with Enhertu include interstitial lung disease or pneumonitis, neutropenia, nausea, fatigue, anemia and thrombocytopenia, while pertuzumab has its own established safety considerations. Appropriate monitoring and management are therefore important when administering the regimen. The European Commission’s decision represents a significant regulatory milestone for AstraZeneca and Daiichi Sankyo and provides European clinicians with a new first-line treatment strategy for HER2-positive metastatic breast cancer. With more than a decade since a new regimen was introduced in this setting, the approval marks an important development in the ongoing effort to improve outcomes for patients with advanced HER2-positive disease.
Source: AstraZeneca and Daiichi Sankyo press relese
