ROSETTA Gastric-204: A Blinded, Randomized, Phase 2/3 Study of Pumitamig in Combination With Chemotherapy Versus Nivolumab in Combination With Chemotherapy in Participants With Previously Untreated Advanced or Metastatic Gastric, Gastroesophageal Junction, or Esophageal Adenocarcinoma

Inclusion Criteria * Participants must be previously untreated with systemic treatment for advanced/metastatic disease, histologically or cytologically confirmed advanced or metastatic gastric cancer (GC), gastroesophageal junction adenocarcinoma (GEJC) or distal esophageal adenocarcinoma (EAC). GEJ involvement can be confirmed via biopsy, endoscopy, or imaging. * Participants must have a documented programmed cell death-(ligand)1 (PD-L1) ≥ 1 or \< 1 status for Phase 2, and document PD-L1 ≥ 1 status for the Phase 3 part of the study. * Participants must have documented human epidermal growth…