AstraZeneca and Daiichi Sankyo have reported that their drug candidate Enhertu (trastuzumab deruxtecan) showed a greater progression-free survival (PFS) and objective response rate (ORR) in the Phase III DESTINY-Breast03 clinical trial for breast cancer.
A HER2-directed antibody-drug conjugate, Enhertu is being co-developed by both companies.
The international, head-to-head, open-label, randomised, registrational trial is analysing Enhertu’s safety and efficacy as against trastuzumab emtansine (T-DM1).
It enrolled a total of 500 individuals with HER2-positive unresectable and/or metastatic breast cancer who already received treatment with trastuzumab and a taxane.
The trial recruited subjects at various study centres in Europe, Asia, North America, South America and Oceania.
PFS is the primary efficacy goal of the trial while overall survival, duration of response, ORR, investigator evaluated PFS and safety were included as secondary efficacy goals.
According to the latest data, Enhertu showed an increased PFS and ORR compared to T-DM1 in pre-specified subject subgroups.
In trial subjects with stable brain metastases at baseline, Enhertu treatment offered a greater PFS of a median of 15 months versus three months in the T-DM1 arm.
For the same group of patients, Enhertu provided a confirmed ORR of 67.4% against 20.5% in the T-DM1 arm.
The safety profile of the most prevalent side effect with Enhertu treatment in the trial was found to be in line with prior breast cancer trial data of the drug without any new safety signals detected.
Nearly 10.5% of the subjects in the Enhertu arm had adjudicated treatment-associated interstitial lung disease or pneumonitis versus 1.9% in the T-DM1 arm.
Daiichi Sankyo R&D global head Ken Takeshita said: “These additional analyses from DESTINY-Breast03 continue to demonstrate the benefit of Enhertu compared to T-DM1 in patient subgroups, including 15-month progression-free survival in those with stable brain metastases, illustrating the potential of this treatment to become the new standard of care in patients with previously treated HER2-positive metastatic breast cancer.
“These data will support our ongoing conversations with global health authorities to realise our commitment to bring Enhertu to patients with previously treated HER2-positive breast cancer earlier in the metastatic setting.”
Earlier this month, Daiichi Sankyo dosed the first subject in the Phase III DESTINY‑Breast11 trial of Enhertu for treating breast cancer.