AstraZeneca and Daiichi Sankyo’s Enhertu Shows Strong Phase III Results in HER2-Positive Early Breast Cancer

AstraZeneca and Daiichi Sankyo announced positive interim results from the DESTINY-Breast05 Phase III trial, reinforcing Enhertu’s (trastuzumab deruxtecan) potential as a foundational treatment for HER2-positive early breast cancer. The trial showed that Enhertu significantly improved invasive disease-free survival compared to trastuzumab emtansine (T-DM1) in patients with residual invasive disease after neoadjuvant treatment, who are at high risk of recurrence. This marks the second positive Phase III trial for Enhertu in this setting, following earlier encouraging results from the DESTINY-Breast11 neoadjuvant trial.

While overall survival data is not yet mature, it will be evaluated in a future analysis. Approximately half of patients with HER2-positive early breast cancer have residual disease after neoadjuvant therapy, which increases their risk of recurrence despite additional treatments. New options like Enhertu are needed to improve long-term outcomes and reduce progression to metastatic disease.

Susan Galbraith, AstraZeneca’s Executive Vice President of Oncology R&D, highlighted that this is the first trial directly comparing Enhertu to T-DM1 in early breast cancer, with results indicating Enhertu may be a superior option in the post-neoadjuvant setting. Ken Takeshita, Daiichi Sankyo’s Global Head of R&D, emphasized the importance of optimizing treatment for patients with residual disease to prevent progression, noting that Enhertu extends the time patients live free of invasive disease.

The safety profile of Enhertu in the trial was consistent with previous studies, with no new safety concerns identified. Enhertu is a HER2-directed antibody drug conjugate jointly developed by AstraZeneca and Daiichi Sankyo.

Data from the DESTINY-Breast05 and DESTINY-Breast11 trials will be presented at the European Society for Medical Oncology (ESMO) Congress 2025 during a Presidential Symposium. The DESTINY-Breast05 results will also be shared with global regulatory authorities. The trial was conducted in collaboration with leading breast cancer research groups, including NSABP, GBG, AGO-B, and SOLTI.