The U.S. Food and Drug Administration has approved Tevimbra (tislelizumab) in combination with Ziihera (zanidatamab) and chemotherapy for the first-line treatment of adult patients with unresectable locally advanced or metastatic HER2-positive gastric, gastroesophageal junction, or esophageal adenocarcinoma.
The approval follows results from the Phase 3 HERIZON-GEA-01 trial, which enrolled 914 patients across approximately 300 sites in more than 30 countries. The study compared the combination regimen against a control arm of trastuzumab plus chemotherapy, evaluating progression-free survival and overall survival as dual primary endpoints.
Median overall survival reached 26.4 months in the combination group, compared with 19.2 months in the control arm. Progression-free survival was 12.4 months versus 8.1 months, respectively. In patients with PD-L1-negative tumors, median overall survival was 29.7 months with the combination versus 15.8 months in the control group. The regimen demonstrated benefit across both HER2 IHC 3+ and HER2 IHC 2+ subpopulations.
Tevimbra is developed by Jazz Pharmaceuticals and BeOne Medicines under license agreements from Zymeworks. The drug has prior approvals in over 50 countries, with more than 2 million patients treated globally. Ziihera, the HER2-targeting component, is co-developed by Zymeworks and Jazz Pharmaceuticals.
HER2-positive disease accounts for approximately 20% of gastroesophageal adenocarcinoma cases. In the U.S., over 31,000 new stomach cancer diagnoses occur annually, with fewer than 40% of advanced HER2-positive patients surviving beyond two years.
