First Astellus/AstraZeneca (AZN.US) blockbuster ADC therapy is poised to secure EU approval.

First and third-party and AstraZeneca (AZN.US) recently announced that their jointly developed antibody-drug conjugate (ADC) Enhertu (trastuzumab deruxtecan) has been recommended for approval in the European Union by the European Medicines Agency's (EMA) Committee for Medicinal Products for Human Use (CHMP), as a single agent for the treatment of adult patients with unresectable or metastatic hormone receptor (HR) positive, human epidermal growth factor receptor 2 (HER2) low-expressing or HER2-low-expressing breast cancer who have received at least one prior endocrine therapy for metastatic disease and are considered not suitable for endocrine therapy as a next-line treatment.

Enhertu is an ADC therapy jointly developed by AstraZeneca and Daiichi Sankyo. It is designed using Daiichi Sankyo's proprietary DXd ADC technology platform, composed of a humanized monoclonal antibody targeting HER2 linked to a topoisomerase I inhibitor payload via a tetrapeptide cleavable linker. Enhertu is the first HER2-targeting ADC with an indication not limited to a specific cancer type.

The positive opinion of CHMP was based on the results of the phase 3 clinical trial DESTINY-Breast. The results were presented at the 2024 American Society of Clinical Oncology (ASCO) annual meeting and published in the New England Journal of Medicine. In the trial, Enhertu reduced the risk of disease progression or death by 38% compared to chemotherapy in patients with HR-positive, HER2-low-expressing metastatic breast cancer who had not received chemotherapy (HR=0.62; 95% CI, 0.52–0.75; p<0.0001), with a median progression-free survival (PFS) of 13.2 months in the Enhertu group versus 8.1 months in the chemotherapy group. In the DESTINY-Breast06 trial, the safety profile of Enhertu was consistent with previous breast cancer clinical trials, without any new safety issues.