On August 25, 2026, the Food and Drug Administration approved zanidatamab-hrii (Ziihera, Jazz Pharmaceuticals). FDA also approved two companion diagnostic devices, the PATHWAY anti-HER-2/neu (4B5) Rabbit Monoclonal Primary Antibody and the VENTANA HER2 Dual ISH DNA Probe Cocktail (Ventana Medical Systems, Inc./Roche Diagnostics), for identifying patients with HER2-positive (IHC3+ or IHC2+/ISH+) gastric, gastroesophageal junction, and esophageal adenocarcinoma for treatment with Ziihera, consistent with the approved drug labeling.