On Dec. 20, 2019, the U.S. Food and Drug Administration (FDA) granted accelerated approval to Daiichi Sankyo’s Enhertu for the treatment of adults with unresectable or metastatic HER2-positive breast cancer who had received two or more prior anti-HER2-based regimens in the metastatic setting.

Approval was based on data from study DS8201-A-U201 (DESTINY-Breast01) with supportive safety data from study DS8201-A-J101. The primary efficacy endpoint in DESTINY-Breast01 was overall response rate (ORR) based on confirmed responses by blinded independent central review (ICR) using RECIST v1.1 in all participants who were assigned to receive the recommended dose of 5.4 mg/kg while secondary endpoints included duration of response (DoR).

The confirmed ORR based on ICR in these 184 patients was 60.3% (95% CI: 52.9, 67.4) and the median DoR was 14.8 months (95% CI: 13.8, 16.9). Interstitial lung disease (ILD), including pneumonitis, was experienced in patients treated with T-DXd and can be severe, life-threatening or fatal. In addition, neutropenia and left ventricular dysfunction were included as Warnings and Precautions in labeling.

Other important common adverse reactions were nausea, fatigue, vomiting, alopecia, constipation, decreased appetite, anemia, diarrhea, and thrombocytopenia.

Overall, the totality of efficacy and safety data supported the accelerated approval of T-DXd for the intended indication.