AstraZeneca and Daiichi Sankyo have reported positive results from the Phase III DESTINY-Breast03 clinical trial of Enhertu (trastuzumab deruxtecan) in HER2-positive, unresectable and/or metastatic breast cancer patients.
Based on Daiichi Sankyo’s DXd ADC technology, Enhertu is a HER2-directed antibody-drug conjugate.
In March 2019, the companies entered an international partnership to co-develop and co-market Enhertu, except in Japan where Daiichi Sankyo holds exclusive rights.
The global head-to-head, randomised, open-label, registrational Phase III DESTINY-Breast03 trial compared the safety and efficacy of Enhertu to T-DM1 (trastuzumab emtansine).
It enrolled nearly 500 participants who had already received trastuzumab and taxane treatments at various centres in Asia, Europe, North America, Oceania and South America.
Progression-free survival (PFS) was the trial’s primary efficacy goal.
Secondary efficacy goals of the trial included overall survival (OS), objective response rate, duration of response, clinical benefit rate, and PFS according to investigator evaluation and safety.
At a planned interim analysis, the Independent Data Monitoring Committee (IDMC) noted that the drug offered a statistically significant and clinically meaningful improvement in PFS in trial subjects.
High-level data from the trial showed that Enhertu demonstrated superiority over T-DM1.
Furthermore, the drug exhibited a robust trend toward OS improvement as against T-DM1, even though the OS results are still immature, AstraZeneca noted.
Enhertu’s safety data in the trial is in line with its previous profile without any new safety concerns and Grade 4 or 5 drug-related interstitial lung disease events observed.
AstraZeneca Oncology R&D executive vice-president Susan Galbraith said: “There is a continued need for new options and better outcomes for patients with HER2-positive metastatic breast cancer who often experience disease progression after initial treatment with available standards of care.
“These transformative progression-free survival results demonstrate the superiority of Enhertu compared to T-DM1, and the encouraging safety data may open future opportunities to bring this benefit to patients in earlier treatment settings.”
The companies plan to share the latest data with global regulatory health authorities.
In June 2021, Daiichi Sankyo and AstraZeneca dosed the first subject in a Phase III DESTINY‑Breast09 trial of Enhertu with or without pertuzumab.