Updated results from the positive DESTINY-Breast01 Phase II trial showed AstraZeneca and Daiichi Sankyo Company, Limited (Daiichi Sankyo)’s Enhertu (trastuzumab deruxtecan) continued to demonstrate impressive efficacy and durable responses in patients with HER2-positive metastatic breast cancer following two or more prior HER2-based regimens.

The updated data were presented in a Spotlight Poster Discussion at the 2020 San Antonio Breast Cancer Symposium (SABCS).

With a median duration of follow-up of 20.5 months, patients treated with Enhertu (5.4 mg/kg) achieved an objective response rate (ORR) of 61.4% and a median duration of response (DoR) of 20.8 months. The median progression-free survival (PFS) was 19.4 months. In an exploratory landmark analysis of overall survival (OS), evaluated at 35% maturity, an estimated 74% of patients remained alive at 18 months.

In the previous analysis at 11.1 months of follow-up, an ORR of 60.9% was seen with a median DoR of 14.8 months and median PFS of 16.4 months. Additional trials are ongoing to confirm the results seen in DESTINY-Breast01.

Approximately one in five patients with breast cancer are considered HER2 positive, which is associated with aggressive disease, high recurrence rate, and increased mortality.

Shanu Modi, MD, Breast Medical Oncologist, Memorial Sloan Kettering Cancer Center and principal investigator in the DESTINY-Breast01 trial, said: “These longer-term data from the DESTINY-Breast01 trial further highlight the role that this treatment option may have in changing clinical outcomes for patients with previously treated HER2-positive metastatic breast cancer. It is important that we are able to offer patients therapy like this which provides a meaningful clinical benefit, as historically there have been few therapies that were able to do that in this patient population.”

José Baselga, Executive Vice President, Oncology R&D, said: “These results reinforce the transformational potential of Enhertu in patients with previously treated HER2-positive metastatic breast cancer. With a median duration of response of greater than twenty months, the updated results of DESTINY-Breast01 are unprecedented. We look forward to further confirming the DESTINY-Breast01 findings with results from our Phase III development programme for Enhertu.”

Antoine Yver, Executive Vice President and Global Head, Oncology R&D, Daiichi Sankyo, said: “The updated findings illustrate the practice-changing potential for Enhertu to become a long-term treatment option for patients with previously treated HER2-positive metastatic breast cancer. The duration of response and long-term safety profile further validate that our proprietary DXd antibody drug conjugate technology delivers effective and durable treatment.”