Enhertu shows 72% reduction in progression or death risk versus T-DM1 in HER2-positive breast cancer

AstraZeneca and Daiichi Sankyo announced that their HER2-directed antibody-drug conjugate, Enhertu (trastuzumab deruxtecan), demonstrated superior efficacy compared to trastuzumab emtansine (T-DM1) in patients with HER2-positive unresectable and/or metastatic breast cancer. The findings come from the Phase III DESTINY-Breast03 trial, presented at the European Society for Medical Oncology (ESMO) Congress.

At a pre-specified interim analysis, Enhertu showed a 72% reduction in the risk of disease progression or death versus T-DM1. The median progression-free survival (PFS) was not reached in the Enhertu arm, compared to 6.8 months for T-DM1, per blinded independent central review. Investigator-assessed median PFS was 25.1 months for Enhertu versus 7.2 months for T-DM1.

The confirmed objective response rate (ORR) was 79.7% for Enhertu compared to 34.2% for T-DM1. Complete responses were observed in 16.1% of patients treated with Enhertu, versus 8.7% in the T-DM1 arm.

The safety profile of Enhertu in this trial was consistent with previous studies, with no new safety concerns identified. Treatment-related interstitial lung disease (ILD) or pneumonitis occurred in 10.5% of patients, with the majority being low grade.

Updated results from the DESTINY-Breast01 Phase II trial were also presented, reinforcing Enhertu's efficacy and durable responses in patients with previously treated HER2-positive metastatic breast cancer.