Ziihera® (zanidatamab-hrii) Combinations Achieve Unprecedented Results in First-Line HER2+ Locally Advanced or Metastatic GEA Including More Than Two Years Median Overall Survival Benefit

Core Insights - The Phase 3 HERIZON-GEA-01 trial results indicate that Ziihera (zanidatamab-hrii) in combination with chemotherapy, with or without tislelizumab, is positioned to become the new standard of care for HER2-positive first-line metastatic gastroesophageal adenocarcinoma (GEA) [1][2][4] Efficacy Summary - The trial achieved a median overall survival (OS) of 26.4 months for Ziihera plus tislelizumab and chemotherapy, which is the longest reported in a Phase 3 trial for this indication, showing a greater than seven-month improvement compared to the control arm [2][4][5] - Median progression-free survival (PFS) was over one year, with a 35% reduction in the risk of disease progression or death compared to trastuzumab plus chemotherapy, representing a more than four-month improvement [4][5] - The objective response rate (ORR) was 70.7% for Ziihera plus tislelizumab and chemotherapy, compared to 65.7% for the control arm [5] Safety Profile - The safety profile of Ziihera in combination with chemotherapy was consistent with known effects of HER2-directed therapy, with no new safety signals identified [6][7] - Grade 3 treatment-related adverse events (TRAEs) were reported at 71.8% for Ziihera plus tislelizumab and chemotherapy, and 59.0% for Ziihera plus chemotherapy [6] - The most common Grade 3 TRAE was diarrhea, occurring in 24.5% of patients receiving Ziihera plus tislelizumab and chemotherapy [6] Future Developments - Jazz Pharmaceuticals plans to submit Ziihera for FDA approval based on these results and is also evaluating Ziihera in other HER2-driven tumor types, including HER2-positive metastatic breast cancer [7][8] - An investor webcast is scheduled to discuss the Ziihera data presented at the ASCO GI symposium [8] Trial Details - The HERIZON-GEA-01 trial was a global, randomized, open-label study involving 914 patients across more than 30 countries, comparing Ziihera plus chemotherapy (with or without tislelizumab) to trastuzumab plus chemotherapy [9]