British-Swedish biopharmaceutical company AstraZeneca plc (STO:AZN) (LON:AZN) (Nasdaq:AZN) and Japanese healthcare company Daiichi Sankyo Co Ltd (TYO:4568) on Wednesday announced positive high-level results from the DESTINY-Breast11 Phase III trial evaluating Enhertu in high-risk, HER2-positive early-stage breast cancer.

Enhertu (trastuzumab deruxtecan), followed by paclitaxel, trastuzumab and pertuzumab (THP), demonstrated a statistically significant and clinically meaningful improvement in pathologic complete response compared to the standard ddAC-THP regimen in the neoadjuvant setting.

The safety profile of Enhertu followed by THP was favourable versus standard of care, with no new safety concerns reported and similar rates of interstitial lung disease.

Event-free survival data, a secondary endpoint, showed an early positive trend but remains immature; follow-up will continue.

This marks the first Phase III trial to demonstrate a benefit for Enhertu in early-stage breast cancer, reinforcing its potential as a neoadjuvant therapy.

Roughly one-third of early-stage breast cancer patients are considered high risk, and current anthracycline-based regimens carry tolerability and long-term safety challenges.

The Independent Data Monitoring Committee recommended halting enrolment in a third trial arm testing Enhertu alone, following a prior interim analysis.

Full data will be presented at an upcoming medical meeting and submitted to regulatory authorities.