Daiichi Sankyo Co., Ltd. (TSE: 4568), headquartered in Tokyo, and AstraZeneca (LSE/STO/NYSE: AZN), headquartered in Cambridge, UK, announced that the U.S. Food and Drug Administration (FDA) accepted and granted Priority Review to a supplemental Biologics License Application (sBLA) for ENHERTU (fam-trastuzumab deruxtecan-nxki), a HER2-directed antibody-drug conjugate (ADC), 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. The Prescription Drug User Fee Act (PDUFA) target action date is July 7, 2026.
Priority Review shortens the FDA's standard review clock to approximately eight months and is reserved for applications that may offer a meaningful benefit over available therapy through improvements in safety, efficacy, or the prevention of a serious condition. The designation follows Breakthrough Therapy Designation (BTD) granted in December 2025 for the same indication. The sBLA is also being reviewed under Project Orbis, the FDA's framework for concurrent international review of oncology products.
The application rests on data from the Phase III DESTINY-Breast05 trial (NCT04622319), a global, multicenter, randomized, open-label study that enrolled 1,635 patients across Asia, Europe, North America, Oceania, and South America. DESTINY-Breast05 compared ENHERTU (5.4 mg/kg) with trastuzumab emtansine (T-DM1) in patients with HER2-positive early breast cancer and residual invasive disease in the breast or axillary lymph nodes following neoadjuvant therapy. High recurrence risk was defined as presentation with inoperable cancer prior to neoadjuvant therapy or pathologically positive axillary lymph nodes afterward. On the primary endpoint of investigator-assessed invasive disease-free survival (IDFS), ENHERTU reduced the risk of invasive disease recurrence or death by 53% versus T-DM1 (hazard ratio [HR]=0.47; 95% confidence interval [CI]: 0.34–0.66; p<0.0001). Three-year IDFS rates were 92.4% (95% CI: 89.7–94.4) and 83.7% (95% CI: 80.2–86.7), respectively. ENHERTU also reduced the risk of distant recurrence by 51% (HR=0.49; 95% CI: 0.34–0.71) and brain metastasis by 36% (HR=0.64; 95% CI: 0.35–1.17). Grade 3 or higher treatment-emergent adverse event rates were comparable between ENHERTU (50.6%) and T-DM1 (51.9%). Interstitial lung disease (ILD) or pneumonitis occurred in 9.6% of the ENHERTU arm versus 1.6% for T-DM1; two grade 5 ILD events (0.2%) were reported in the ENHERTU arm. ENHERTU was discovered by Daiichi Sankyo using its proprietary DXd ADC technology platform and has been jointly developed and commercialized with AstraZeneca under a global collaboration established in March 2019. Regulatory submissions based on DESTINY-Breast05 are also under review in the EU and Japan. Separately, an sBLA for ENHERTU followed by paclitaxel, trastuzumab, and pertuzumab in the neoadjuvant setting, based on the DESTINY-Breast11 trial, carries a PDUFA date of May 18, 2026.