AstraZeneca PLC filed a Form 6-K on 27 October 2026 disclosing that the European Commission approved Enhertu (trastuzumab deruxtecan) as an adjuvant monotherapy for adult patients with resected HER2-positive breast cancer who have residual invasive disease after neoadjuvant taxane-based and HER2-targeted treatment.

Key Highlights

  • EU Approval Granted: The European Commission approved Enhertu for the adjuvant treatment of adult patients with resected HER2-positive breast cancer with residual invasive disease after neoadjuvant therapy.
  • 53% Risk Reduction: In the DESTINY-Breast05 Phase III trial, Enhertu reduced the risk of invasive disease recurrence or death by 53% versus T-DM1 (hazard ratio 0.47; 95% CI 0.34-0.66; p<0.0001), according to the filing.
  • Three-Year IDFS Rate: Enhertu demonstrated a three-year invasive disease-free survival rate of 92.4% (95% CI 89.7-94.4) compared to 83.7% with T-DM1 (95% CI 80.2-86.7), as reported in the filing.
  • $75 Million Milestone Payment: Following the EU approval, AstraZeneca disclosed that $75 million is due to Daiichi Sankyo as a milestone payment for the adjuvant HER2-positive early breast cancer indication.
  • First EU Approval in Early Breast Cancer Setting: The filing describes this as the first EU approval of Enhertu in the curative-intent early breast cancer setting.
  • Trial Enrollment: DESTINY-Breast05 enrolled 1,635 patients across Asia, Europe, North America, Oceania, and South America, according to the filing.

AstraZeneca and Daiichi Sankyo Secure EU Adjuvant Approval for Enhertu Based on DESTINY-Breast05 Results

According to the Form 6-K filed by AstraZeneca PLC (NYSE:AZN) for the month of October 2026, the European Commission granted approval for Enhertu (trastuzumab deruxtecan) as a monotherapy in the adjuvant setting for adult patients with resected HER2-positive breast cancer who have residual invasive disease after neoadjuvant taxane-based and HER2-targeted treatment. The filing states that the approval follows a positive opinion from the Committee for Medicinal Products for Human Use of the European Medicines Agency.

The approval is based on results from the DESTINY-Breast05 Phase III trial, described in the filing as a global, multicentre, randomised, open-label study evaluating Enhertu (5.4mg/kg) versus trastuzumab emtansine (T-DM1). The filing states that Enhertu reduced the risk of invasive disease recurrence or death by 53%, corresponding to a hazard ratio of 0.47 (95% CI 0.34-0.66; p<0.0001). The three-year invasive disease-free survival rate was reported as 92.4% for Enhertu versus 83.7% for T-DM1. The filing notes that "the safety profile of Enhertu was consistent with the known profile with no new safety concerns identified."

The filing discloses a financial consequence of the approval: a milestone payment of $75 million is due from AstraZeneca to Daiichi Sankyo for the adjuvant HER2-positive early breast cancer indication. The filing also notes that sales of Enhertu in most EU territories are recognised by Daiichi Sankyo, and directs readers to the collaboration agreement from March 2019 for further details on financial arrangements. The filing states that Enhertu is now approved in more than 35 countries for the adjuvant treatment of adult patients with HER2-positive breast cancer who have residual invasive disease following neoadjuvant trastuzumab and taxane-based treatment based on the DESTINY-Breast05 trial.

What Was Disclosed

AstraZeneca's October 2026 Form 6-K disclosed the European Commission's approval of Enhertu in the adjuvant early breast cancer setting, the key efficacy and safety results from the DESTINY-Breast05 trial supporting that approval, and a $75 million milestone payment obligation to Daiichi Sankyo.