This is a phase 1/2, multicenter, open-label umbrella platform study that will evaluate the safety and tolerability of investigational agents with pembrolizumab and fluoropyrimidine chemotherapy for the first-line (1L) treatment of participants with locally advanced unresectable or metastatic human epidermal growth factor receptor 2 (HER2)-negative gastric, gastroesophageal junction, or esophageal adenocarcinoma.
This substudy will have two phases: a safety lead-in phase and an efficacy phase. The safety lead-in phase will be used to evaluate the safety and tolerability, and to establish a recommended Phase 2 dose (RP2D) for investigational agents in combination with chemotherapy and immunotherapy. There is no formal hypothesis in this study.
Has histologically and/or cytologically confirmed diagnosis of previously untreated locally advanced unresectable or metastatic first-line (1L) gastroesophageal adenocarcinoma
Is not expected to require tumor resection during the treatment course
Tumor tissue must be confirmed as negative for human epidermal growth factor receptor 2 (HER2) expression as classified by American Society of Clinical Oncology/College of American Pathologists (ASCO-CAP) guidelines
Core/excisional biopsy of a tumor lesion not previously irradiated has been provided
Has squamous cell or undifferentiated gastroesophageal cancer.
Has had previous therapy for locally advanced unresectable or metastatic gastric/gastroesophageal junction (GEJ)/esophageal adenocarcinoma
Has experienced weight loss >20% over 3 months before the first dose of study intervention
Has a history of documented severe dry eye syndrome, severe Meibomian gland disease and/or blepharitis, or severe corneal disease that prevents/delays corneal healing