HERIZON-GEA-01: Zanidatamab + chemo ± tislelizumab for 1L treatment of HER2-positive gastroesophageal adenocarcinoma.

HER2-positive gastroesophageal adenocarcinomas (GEAs) are common cancers with high mortality and the treatment options for advanced/metastatic disease are limited. Zanidatamab and tislelizumab are novel monoclonal antibodies targeting HER2 and PD-1, respectively, and have shown encouraging antitumor activity in early phase studies in multiple cancers, including GEA. Preliminary data suggest that dual targeting of the HER2 and PD-1 pathways could further improve upon the results achieved with targeting either pathway alone. Here, we describe the design of HERIZON-GEA-01, a global, randomized, open-label, active-comparator, Phase III study to evaluate and compare the efficacy and safety of zanidatamab plus chemotherapy with or without tislelizumab to the standard of care (trastuzumab plus chemotherapy) as first-line treatment for patients with advanced/metastatic HER2-positive GEAs.