AstraZeneca-Daiichi Sankyo get USFDA grants priority review for Enhertu combo for 1st line HER2+ Breast cancer treatment

The Food and Drug Administration (FDA) grants Priority Review to applications for medicines that, if approved, would offer significant improvements over available treatment options by demonstrating safety or efficacy improvements, preventing serious conditions or enhancing patient compliance. The Prescription Drug User Fee Act date, the FDA action date for their regulatory decision, is anticipated during the first quarter of 2026.

Enhertu was also recently granted Breakthrough Therapy Designation (BTD) by the FDA in this setting. BTD accelerates the development and regulatory review of potential new medicines intended to treat a serious condition and address a significant unmet medical need.

HER2-positive metastatic breast cancer is an aggressive disease driven by overexpression or amplification of HER2 that affects 15% to 20% of patients with metastatic breast cancer. Approximately 10,000 patients are treated each year in the 1st-line HER2-positive metastatic setting in the US.

Susan Galbraith, Executive Vice President, Oncology Haematology R&D, AstraZeneca, said, “The DESTINY-Breast09 trial showed that treating patients with HER2-positive metastatic breast cancer with Enhertu in combination with pertuzumab until progression in the first-line setting produced a new landmark of more than 40 months for progression-free survival and nearly doubled the number of patients with no evidence of disease on imaging. This marks the first major evolution in treatment in this first-line setting in more than a decade – a setting where a strong response is crucial, as up to one third of patients may not receive second-line therapy.”

Ken Takeshita, Global Head, R&D, Daiichi Sankyo, said, “Enhertu in combination with pertuzumab delayed disease progression for more than three years compared to around two years with current standard of care as a first-line treatment for patients with HER2-positive metastatic breast cancer. Receiving Priority Review moves us closer to offering Enhertu to patients even earlier in the metastatic treatment pathway as a potential new first-line treatment option.”

The sBLA is being reviewed under the Real-Time Oncology Review (RTOR) programme, an initiative of the FDA designed to bring safe and effective cancer treatments to patients as early as possible. RTOR allows the FDA to review components of an application before submission of the complete application.

The sBLA is based on data from the DESTINY-Breast09 Phase III trial presented as a special late-breaking oral session at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting. In the trial, Enhertu in combination with pertuzumab reduced the risk of disease progression or death by 44% versus a taxane, trastuzumab and pertuzumab (THP) (based on a hazard ratio of 0.56; 95% confidence interval 0.44-0.71; p<0.00001) as a 1st-line treatment for patients with HER2-positive metastatic breast cancer.

Median progression-free survival (PFS) was 40.7 months with Enhertu plus pertuzumab compared to 26.9 months for THP. The PFS benefit for Enhertu plus pertuzumab versus THP was consistent across subgroups.

Confirmed objective response rate (ORR) with Enhertu plus pertuzumab was 85.1% versus 78.6% with THP. There were 58 complete responses (CRs) with Enhertu plus pertuzumab compared to 33 CRs with THP.

The safety profile of Enhertu plus pertuzumab in DESTINY-Breast09 was consistent with the known profiles of each individual therapy with no new safety concerns identified.

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

Enhertu is already approved in more than 85 countries as 2nd-line treatment for patients with HER2-positive breast cancer based on the results from the DESTINY-Breast03 Phase III trial.