Daiichi Sankyo announced that ENHERTU (trastuzumab deruxtecan) has been approved in Japan for the treatment of adult patients with HER2 positive unresectable or recurrent breast cancer after prior chemotherapy, which includes trastuzumab and a taxane.

The approval by Japan’s Ministry of Health, Labour and Welfare (MHLW) was based on the results of the DESTINY-Breast03 trial where ENHERTU demonstrated a 72% reduction in the risk of disease progression or death compared to trastuzumab emtansine (T-DM1) (hazard ratio [HR] = 0.28; 95% confidence interval in patients with HER2 positive unresectable and/or metastatic breast cancer previously treated with trastuzumab and a taxane. The median progression-free survival (PFS) for patients treated with ENHERTU was not reached (95% CI: 18.5-NE) compared to 6.8 months for T-DM1 (95% CI: 5.6-8.2) as assessed by blinded independent central review (BICR).

Data from DESTINY-Breast03 has met the requirement for a confirmatory phase 3 trial as part of the conditional early approval received in Japan in March 2020.

“We are proud of the quality and speed in which we were able to deliver a confirmatory phase 3 trial that demonstrated the superiority of ENHERTU in prolonging progression-free survival compared to T-DM1 in patients with previously treated HER2 positive metastatic breast cancer,” said Wataru Takasaki, PhD, Executive Officer, Head of R&D Division in Japan, Daiichi Sankyo. “This approval by the MHLW highlights the importance of the conditional approval system in Japan that allows for early approval of medicines to treat serious conditions such as breast cancer.”

Efficacy and safety of ENHERTU in patients without prior trastuzumab and a taxane, or as a neoadjuvant or adjuvant therapy, has not been established. ENHERTU is approved in Japan with a Warning for Interstitial Lung Disease (ILD). As cases of ILD, including fatal cases, have occurred in ENHERTU-treated patients, ENHERTU is to be used in close collaboration with a respiratory disease expert.