AstraZeneca, Daiichi Sankyo's Enhertu Regimen Greenlit as First-line Breast Cancer Treatment in US

01:00 AM EST, 12/16/2025 (MT Newswires) -- AstraZeneca (AZN.L, AZN.ST) on Monday said Enhertu plus pertuzumab won approval in the US as the first-line treatment of adult patients with unresectable or metastatic HER2-positive breast cancer. Generically labelled trastuzumab deruxtecan, Enhertu was discovered by the drugmaker's Japanese peer, Daiichi Sankyo, and is being jointly developed and commercialized by both pharmaceuticals. The specifically engineered HER2-directed DXd antibody drug conjugate was initially approved six years ago. With the US approval of Enhertu in the first-line HER2-positive metastatic setting, AstraZeneca will make a milestone payment of $150 million to Daiichi Sankyo, which recognizes the US sales of the drug. The latest approval followed the US Food and Drug Administration's priority review and breakthrough therapy designation and is based on the results from the Destiny-Breast09 phase 3 trial. The data showed reduced disease progression or death risk by 44%, compared with taxane, trastuzumab, and pertuzumab. The safety profile was consistent with the known profiles of each therapy. "Trastuzumab deruxtecan plus pertuzumab is the only 1st-line treatment approved in more than a decade to demonstrate a statistically significant improvement in progression-free survival over the current standard regimen for patients with HER2-positive metastatic breast cancer," said the trial's principal investigator, Sara Tolaney. "With a median progression-free survival exceeding three years, versus approximately two years with THP, trastuzumab deruxtecan combined with pertuzumab should become a new 1st-line standard of care in this setting." The first-line regimen is currently under review by Swissmedic and Singapore's Health Sciences Authority, as well as other countries. Besides Enhertu, AstraZeneca has a portfolio of approved and potential compounds in development to address breast cancer, including Datroway or datopotamab deruxtecan, next-generation oral SERD, and potential new medicine camizestrant.