Impressive Phase III results for Enhertu plus pertuzumab

The DESTINY-Breast09 Phase III trial of AstraZeneca (LSE: AZN) and Daiichi Sankyo’s (TYO: 4568) Enhertu (trastuzumab deruxtecan) is the first trial in more than a decade to demonstrate superior efficacy across a broad HER2-positive metastatic patient population versus current first-line standard of care.

The companies noted that positive high-level results from a planned interim analysis of the DESTINY-Breast09 Phase III trial showed Enhertu in combination with pertuzumab demonstrated a highly statistically-significant and clinically-meaningful improvement in progression-free survival (PFS) compared to a taxane, trastuzumab and pertuzumab (THP) as a first-line treatment for patients with HER2-positive metastatic breast cancer.

The PFS improvement was seen across all pre-specified patient subgroups with Enhertu in combination with pertuzumab. The key secondary endpoint of overall survival (OS) was not mature at the time of this planned interim analysis; however, interim OS data showed an early trend favoring the Enhertu combination compared with THP.