Jazz Pharmaceuticals reported second interim overall survival results from the Phase 3 HERIZON-GEA-01 trial, showing that Ziihera (zanidatamab-hrii) combined with chemotherapy produced statistically significant and clinically meaningful overall survival improvements versus trastuzumab plus chemotherapy in first-line treatment for adults with HER2-positive locally advanced or metastatic gastroesophageal adenocarcinoma. The Ziihera-plus-chemotherapy overall survival hazard ratio improved from the first interim analysis, while longer follow-up also improved the hazard ratio for Ziihera plus Tevimbra (tislelizumab-jsgr) and chemotherapy. The company said the updated results reinforce Ziihera as a potential HER2-targeted backbone therapy and support the combination with tislelizumab and chemotherapy as a new U.S. standard of care, although those statements are forward-looking. The data were submitted for presentation at a major medical meeting in the fourth quarter of 2026 and will also be submitted to global health authorities. The FDA approved Ziihera on Aug. 25, 2026, for specified first-line HER2-positive unresectable locally advanced or metastatic GEA regimens. HER2 is a cancer-related protein used to identify tumors that may respond to targeted treatment. GEA includes cancers of the stomach, gastroesophageal junction and esophagus; it is the fifth most common cancer worldwide, about 20% of cases are HER2-positive, and metastatic disease has a global five-year survival rate below 10%. HERIZON-GEA-01 randomized 914 patients across approximately 225 sites in more than 30 countries and evaluated three treatment arms, with progression-free survival and overall survival as dual primary endpoints. Ziihera is a bispecific HER2-directed antibody that binds two extracellular sites on HER2. Its U.S. prescribing information carries Boxed Warnings for severe diarrhea and embryo-fetal toxicity, alongside warnings involving left ventricular dysfunction and other adverse reactions.