AstraZeneca’s Enhertu Achieves Record Response Rate In Phase 3 Trial For Early Breast Cancer

AstraZeneca drew some retail investor attention early Monday after the pharma major reported that its cancer therapy Enhertu, developed with Daiichi Sankyo, achieved the highest pathologic complete response rate ever seen in a Phase 3 study for HER2-positive early breast cancer, showing both superior efficacy and a favorable safety profile compared with standard treatment.

Trial Results Show Record Response Rates

The DESTINY-Breast11 study, presented at the ESMO 2025 Presidential Symposium in Berlin, found that Enhertu followed by paclitaxel, trastuzumab and pertuzumab (THP) led to a pathologic complete response rate of 67.3%, compared with 56.3% for the standard anthracycline-based regimen (ddAC-THP). That marks an 11.2% absolute improvement, seen across both hormone receptor–positive and negative patients.

After surgery, over 81% of patients in the Enhertu group had no or minimal residual invasive cancer compared to 69% of patients treated with standard therapy. An early analysis of event-free survival showed a favorable trend with Enhertu, but the data are not mature.

Doctors See Potential New Standard Of Care

Nadia Harbeck, Director of the Breast Center at LMU University Hospital in Munich and the trial’s lead investigator, said the results suggest Enhertu could become a new standard of care in early, high-risk HER2-positive breast cancer. 

AstraZeneca’s head of oncology R&D Susan Galbraith added that the data show Enhertu “has the potential to transform treatment in the neoadjuvant setting.”

Safety Profile And Regulatory Outlook

Enhertu followed by THP was also better tolerated, with fewer severe side effects compared with standard therapy. Rates of Grade 3 or higher adverse events were 37.5% versus 55.8%, and heart-related side effects were lower. Interstitial lung disease rates were low and consistent across both groups.

The FDA is reviewing a supplemental Biologics License Application for Enhertu in this setting. Enhertu is being developed by AstraZeneca and Japan's Daiichi Sankyo.

Stocktwits Traders Turn Cautious

On Stocktwits, retail sentiment for AstraZeneca was ‘bearish’ amid ‘low’ message volume.

AstraZeneca’s stock has risen 32% so far in 2025.

For updates and corrections, email newsroom[at]stocktwits[dot]com.

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