Trial results for a Phase 3 study evaluating trastuzumab deruxtecan (Enhertu) in HER2-positive early breast cancer were posted on ClinicalTrials.gov on 2026-06-09. The study reported varying pathologic complete response (pCR) rates across its arms, with statistically significant differences observed between treatment groups.
Background
Trastuzumab deruxtecan (Enhertu) was investigated in this study for its efficacy and safety in a neoadjuvant setting for high-risk, HER2-positive early non-metastatic breast cancer. The trial aimed to compare trastuzumab deruxtecan alone or in sequence with other therapies against a standard treatment regimen.
Trial design
The Phase 3 study (NCT05113251) enrolled 927 participants with HER2-positive early breast cancer. The trial investigated trastuzumab deruxtecan (T-DXd) alone or in sequence with paclitaxel, trastuzumab, and pertuzumab (THP), comparing these approaches against a standard treatment regimen (ddAC-THP). The interventions involved in the study included trastuzumab deruxtecan, paclitaxel, trastuzumab, pertuzumab, and doxorubicin. The primary outcome measured was the Rate of Pathologic Complete Response (pCR).
Key results
The trial reported the following rates of pathologic complete response (pCR):
- In Arm A, the pCR rate was 43.01%.
- In Arm B, the pCR rate was 67.29%.
- In Arm C, the pCR rate was 56.25%.
Statistical analysis using Miettinen and Nurminen's method revealed significant differences in pCR rates between arms. One analysis showed an estimated difference in rates of -13.18 (95.0% CI: -20.84 to -5.41; p=0.001). Another analysis indicated an estimated difference in rates of 11.17 (95.0% CI: 3.95 to 18.28; p=0.003).
What this means
The reported results indicate that different treatment regimens involving trastuzumab deruxtecan had distinct impacts on achieving pathologic complete response (pCR) in patients with HER2-positive early breast cancer. The statistically significant differences in pCR rates (p=0.001 and p=0.003) suggest that the variations observed across the study arms are not attributable to random chance. Specifically, the estimated differences in rates of -13.18 and 11.17 highlight the varying efficacy profiles of the tested approaches. These findings provide important data for clinicians and researchers assessing optimal neoadjuvant strategies for this patient population.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for the study NCT05113251, titled "Trastuzumab Deruxtecan (T-DXd) Alone or in Sequence With THP, Versus Standard Treatment (ddAC-THP), in HER2-positive Early Breast Cancer", were posted on 2026-06-09 on clinicaltrials.gov.