Daiichi Sankyo (TSE: 4568) and AstraZeneca’s (LSE/STO/NYSE: AZN) supplemental Biologics License Application (sBLA) for ENHERTU^® (fam-trastuzumab deruxtecan-nxki) has been accepted and granted Priority Review in the U.S. for the treatment of adult patients with HER2 positive (immunohistochemistry [IHC] 3+ or in-situhybridization (ISH)+) breast cancer who have residual invasive disease after neoadjuvant HER2 targeted treatment.

ENHERTU is a specifically engineered HER2 directed DXd antibody drug conjugate (ADC) discovered by Daiichi Sankyo and being jointly developed and commercialized by Daiichi Sankyo and AstraZeneca.

The U.S. Food and Drug Administration (FDA) grants Priority Review to applications for medicines that, if approved, would offer significant benefit over available treatment options by demonstrating safety or efficacy improvements, preventing serious conditions or enhancing patient compliance. The Priority Review follows receipt of Breakthrough Therapy Designation granted by the FDA in December 2025 for ENHERTU based on data from the DESTINY-Breast05phase 3 trial presented at the 2025 European Society of Medical Oncology (#ESMO25) Congress and subsequently published in The New England Journal of Medicine. The Prescription Drug User Fee Act (PDUFA) date, the FDA target action date for their regulatory decision, is July 7, 2026.

Results from DESTINY-Breast05 showed ENHERTU significantly reduced the risk of invasive disease recurrence or death (invasive disease-free survival [IDFS]) by 53% (hazard ratio [HR]=0.47; 95% confidence interval [CI]: 0.34-0.66; p<0.0001) compared to trastuzumab emtansine (T-DM1) as a post-neoadjuvant treatment for patients with HER2 positive breast cancer with residual invasive disease following neoadjuvant therapy. Trial results demonstrated a three-year IDFS rate of 92.4% (95% CI: 89.7-94.4) in the ENHERTU arm compared to 83.7% with T-DM1 (95% CI: 80.2-86.7). IDFS findings were consistent across all prespecified subgroups.

Data also showed that ENHERTU significantly reduced the risk of disease recurrence or death by 53% (HR=0.47; 95% CI: 0.34-0.66; p<0.0001) compared to T-DM1. Treatment with ENHERTU in DESTINY-Breast05 also reduced the risk of distant disease recurrence (distant recurrence-free interval [DRFI]) by 51% (HR=0.49; 95% CI: 0.34-0.71) and the risk of brain metastases (brain metastasis-free interval [BMFI]) by 36% (HR=0.64; 95% CI: 0.35-1.17) versus T-DM1.

The sBLA is being reviewed under Project Orbis, which provides a framework for the concurrent submission and review of oncology medicines among participating international partners. This initiative is designed to bring effective cancer treatments to patients as early as possible.

“For patients with residual invasive disease after neoadjuvant therapy, identifying additional treatments following surgery is critical to help further reduce the risk of recurrence and help prevent progression to metastatic disease,” said Ken Takeshita, MD, Global Head, R&D, Daiichi Sankyo. “This Priority Review reinforces the potential of ENHERTU to become a new standard of care for HER2 positive early breast cancer based on the results of DESTINY-Breast05.”

“While there has been significant progress in treating HER2 positive early breast cancer, managing patients at a higher risk of recurrence remains challenging,” said Susan Galbraith, MBBChir, PhD, Executive Vice President, Oncology Hematology R&D, AstraZeneca. “With this Priority Review, we move closer to bringing ENHERTU to the post-neoadjuvant setting, offering more patients the opportunity for sustained long-term outcomes and a potential path to cure.”

The safety profile of ENHERTU observed in DESTINY-Breast05 was consistent with its known profile with no new safety concerns identified. Grade 3 or higher treatment emergent adverse event (TEAE) rates were comparable between ENHERTU (50.6%) and T-DM1 (51.9%). The most common grade 3 or higher TEAEs occurring in 5% or more of patients treated with ENHERTU were decreased neutrophil count (15.5%), decreased white blood cell count (10.1%), decreased platelet count (6.7%) and neutropenia (8.1%). Rates of interstitial lung disease (ILD) or pneumonitis were low in both arms with ILD events occurring in 9.6% of the ENHERTU arm and 1.6% of the T-DM1 arm. The majority of ILD or pneumonitis events were low grade (grade 1 [ENHERTU=16; 2.0%; T-DM1=8; 1.0%] or grade 2 [ENHERTU=52; 6.5%; T-DM1=5; 0.6%]). There were no grade 3 or higher ILD or pneumonitis events for T-DM1. In the ENHERTU arm, there were seven grade 3 events (0.9%) and two grade 5 events (0.2%) as determined by an independent adjudication committee.

Regulatory submissions for ENHERTU based on DESTINY-Breast05 are under review in the EU and Japan. In addition, an sBLA for ENHERTU followed by paclitaxel, trastuzumab and pertuzumab (THP) currently is under review in the U.S. for the neoadjuvant treatment of adult patients with HER2 positive (IHC 3+ or ISH+) stage 2 or stage 3 breast cancer based on results from the DESTINY-Breast11 trial with a PDUFA date of May 18, 2026.