On March 9, 2026 Daiichi Sankyo (TSE: 4568) and AstraZeneca (LSE/STO/NYSE: AZN) reported that its 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-situ hybridization (ISH)+) breast cancer who have residual invasive disease after neoadjuvant HER2 targeted treatment.
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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-Breast05 phase 3 trial presented at the 2025 European Society of Medical Oncology (ESMO) (Free ESMO Whitepaper) (#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.
About DESTINY-Breast05
DESTINY-Breast05 is a global, multicenter, randomized, open-label, phase 3 trial evaluating the efficacy and safety of ENHERTU (5.4 mg/kg) versus T-DM1 in patients with HER2 positive early breast cancer with residual invasive disease in breast or axillary lymph nodes following neoadjuvant therapy and a high risk of recurrence. High risk of recurrence was defined as presentation with inoperable cancer (prior to neoadjuvant therapy) or pathologically positive axillary lymph nodes following neoadjuvant therapy.
The primary endpoint of DESTINY-Breast05 is investigator-assessed IDFS, which is defined as the time from randomization until first invasive local, axillary or distant recurrence or death from any cause. The key secondary endpoint is investigator-assessed DFS. Other secondary endpoints include overall survival, DRFI, BMFI, interval and safety.
DESTINY-Breast05 enrolled 1,635 patients in Asia, Europe, North America, Oceania and South America. For more information about the trial, visit ClinicalTrials.gov.
About Post-Neoadjuvant Treatment for HER2 Positive Early Breast Cancer
Breast cancer is the second most common cancer and one of the leading causes of cancer-related deaths worldwide.1 More than two million breast cancer cases were diagnosed in 2022, with more than 665,000 deaths globally.1 In the U.S., more than 320,000 cases of breast cancer are diagnosed annually with more than 42,000 deaths.2
HER2 is a tyrosine kinase receptor growth-promoting protein expressed on the surface of many types of tumors including breast cancer.3 HER2 protein overexpression may occur as a result of HER2 gene amplification and is often associated with aggressive disease and poor prognosis in breast cancer.3 Approximately one in five cases of breast cancer is considered HER2 positive.4
For patients with HER2 positive early breast cancer, achieving pathologic complete response (pCR) with neoadjuvant treatment is the earliest indicator of improved long-term survival.5 However, approximately half of patients who receive neoadjuvant treatment do not experience pCR, putting them at increased risk of disease recurrence.6,7,8,9,10
Despite receiving additional treatment for residual disease in the post-neoadjuvant setting, some patients still experience invasive disease or death and current treatment options have shown limited impact on central nervous system recurrence.11 Once patients are diagnosed with metastatic disease, the five-year survival rate drops from nearly 90% to approximately 30%.12
Post-neoadjuvant therapy represents a key opportunity to minimize the risk of recurrence and prevent progression to metastatic disease for patients with residual disease. New treatment options are needed in the early breast cancer setting to help reduce the likelihood of disease progression and improve long-term outcomes for more patients.13,14
About ENHERTU
ENHERTU (trastuzumab deruxtecan; fam-trastuzumab deruxtecan-nxki in the U.S. only) is a HER2 directed ADC. Designed using Daiichi Sankyo’s proprietary DXd ADC Technology, ENHERTU is the lead ADC in the oncology portfolio of Daiichi Sankyo and the most advanced program in AstraZeneca’s ADC scientific platform. ENHERTU consists of a HER2 monoclonal antibody attached to a number of topoisomerase I inhibitor payloads (an exatecan derivative, DXd) via tetrapeptide-based cleavable linkers.
ENHERTU (5.4 mg/kg) in combination with pertuzumab is approved in the U.S. as a first-line treatment for adult patients with unresectable or metastatic HER2 positive (IHC 3+ or ISH+) breast cancer, as determined by an FDA-approved test, based on the results from the DESTINY-Breast09 trial.
ENHERTU (5.4 mg/kg) is approved in more than 90 countries/regions worldwide for the treatment of adult patients with unresectable or metastatic HER2 positive (IHC 3+ or ISH+) breast cancer who have received a prior anti-HER2-based regimen, either in the metastatic setting or in the neoadjuvant or adjuvant setting, and have developed disease recurrence during or within six months of completing therapy based on the results from the DESTINY-Breast03 trial.
ENHERTU (5.4 mg/kg) is approved in more than 90 countries/regions worldwide for the treatment of adult patients with unresectable or metastatic HER2 low (IHC 1+ or IHC 2+/ISH-) breast cancer who have received a prior systemic therapy in the metastatic setting or developed disease recurrence during or within six months of completing adjuvant chemotherapy based on the results from the DESTINY-Breast04 trial.
ENHERTU (5.4 mg/kg) is approved in more than 60 countries/regions worldwide for the treatment of adult patients with unresectable or metastatic hormone receptor (HR) positive, HER2 low (IHC 1+ or IHC 2+/ ISH-) or HER2 ultralow (IHC 0 with membrane staining) breast cancer, as determined by a locally or regionally approved test, that have progressed on one or more endocrine therapies in the metastatic setting based on the results from the DESTINY-Breast06 trial.
ENHERTU (5.4 mg/kg) is approved in more than 70 countries/regions worldwide for the treatment of adult patients with unresectable or metastatic NSCLC whose tumors have activating HER2 (ERBB2) mutations, as detected by a locally or regionally approved test, and who have received a prior systemic therapy based on the results from the DESTINY-Lung02 and/or DESTINY-Lung05 trials. Continued approval in China and the U.S. for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.
ENHERTU (6.4 mg/kg) is approved in more than 80 countries/regions worldwide for the treatment of adult patients with locally advanced or metastatic HER2 positive (IHC 3+ or IHC 2+/ISH+) gastric or gastroesophageal junction (GEJ) adenocarcinoma who have received a prior trastuzumab-based regimen based on the results from the DESTINY-Gastric01, DESTINY-Gastric02 and/or DESTINY-Gastric04 trials.
ENHERTU (5.4 mg/kg) is approved in more than 10 countries/regions worldwide for the treatment of adult patients with unresectable or metastatic HER2 positive (IHC 3+) solid tumors who have received prior systemic treatment and have no satisfactory alternative treatment options based on efficacy results from the DESTINY-PanTumor02, DESTINY-Lung01 and DESTINY-CRC02 trials. Continued approval in the U.S. for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.
About the ENHERTU Clinical Development Program
A comprehensive global clinical development program is underway evaluating the efficacy and safety of ENHERTU as a monotherapy or in combination or sequentially with other cancer medicines across multiple HER2 targetable cancers.
(Press release, Daiichi Sankyo, MAR 9, 2026, View Source [SID1234663383])