Zymeworks and BeOne Say Phase 3 Zanidatamab Regimens Top Two Years’ Survival in First-Line HER2+ GEA

Overview

• Company releases report that zanidatamab with chemotherapy, with or without tislelizumab, improved outcomes versus trastuzumab plus chemotherapy in the Phase 3 HERIZON-GEA-01 trial.
• Progression-free survival reached 12.4 months with either zanidatamab regimen versus 8.1 months on control, reflecting about a 35% reduction in risk of progression or death.
• Overall survival at the first interim analysis was 26.4 months for zanidatamab plus tislelizumab and chemotherapy (HR 0.72; P=0.0043) and 24.4 months for zanidatamab plus chemotherapy (HR 0.80; P=0.0564) versus 19.2 months on control.
• Benefits were generally consistent across prespecified subgroups, including PD-L1 status and geographic region, and an additional planned OS interim analysis for the doublet is expected in mid-2026.
• Safety profiles aligned with known effects of HER2-directed therapy and immunotherapy, with higher rates of grade ≥3 diarrhea reported but infrequent treatment discontinuation due to this event.