Overview

• The sBLA from Daiichi Sankyo and AstraZeneca is supported by phase 3 DESTINY-Breast09 results against the current standard regimen of taxane plus trastuzumab and pertuzumab.
• T-DXd plus pertuzumab reduced the risk of progression or death by 44% vs THP (HR 0.56) and delivered a median PFS of 40.7 months vs 26.9 months by blinded central review.
• The confirmed overall response rate was 85.1% with the combination vs 78.6% with THP, including complete responses in 15.1% vs 8.5% of patients.
• Safety findings were consistent with known profiles of the agents with no new signals reported; common events included nausea, diarrhea, neutropenia, fatigue, alopecia, and vomiting.
• The filing follows a July 2025 Breakthrough Therapy designation, and the trial’s T-DXd monotherapy arm remains blinded to final PFS analysis during the FDA’s RTOR review.