FDA expands Enhertu into HER2-positive early breast cancer

Enhertu is moving earlier in breast cancer care. On May 15, 2026, the US FDA approved AstraZeneca and Daiichi Sankyo’s fam-trastuzumab deruxtecan-nxki, sold as Enhertu, for two HER2-positive early-stage breast cancer indications: first, as neoadjuvant treatment before surgery when given for four cycles followed by taxane, trastuzumab, and pertuzumab; and second, as adjuvant treatment after surgery for patients with residual invasive disease following prior neoadjuvant trastuzumab-based and taxane-based therapy. The FDA also cleared two companion diagnostics to identify eligible HER2-positive patients. The decision was backed by the phase 3 DESTINY-Breast11 and DESTINY-Breast05 trials. In DESTINY-Breast11, pathologic complete response was 67.3% with the Enhertu-based regimen versus 56.3% with ddAC-THP. In DESTINY-Breast05, the 3-year invasive disease-free survival rate was 92.4% with Enhertu versus 83.7% with T-DM1. (fda.gov)

Why it matters: For veterinary professionals, this isn’t a practice-changing animal health story, but it is a useful signal about where oncology is heading. Enhertu’s approval expands the role of antibody-drug conjugates into curative-intent, earlier-line treatment, not just metastatic disease. That matters for clinicians tracking translational oncology, comparative cancer research, and the pace at which targeted therapeutics, companion diagnostics, and biomarker-defined treatment pathways are becoming standard in human medicine. It also underscores the growing importance of monitoring boxed-warning toxicities such as interstitial lung disease and pneumonitis as these agents move into broader use. (fda.gov)

What to watch: Next up will be how quickly treatment guidelines, payer coverage, and regulators outside the US incorporate these new early-stage indications, especially since the neoadjuvant data are based on pCR while longer-term event-free survival is still immature. (fda.gov)