A Safety and Efficacy Study of Treatment Combinations With and Without Chemotherapy in Adult Participants With Advanced Upper Gastrointestinal Tract Malignancies

Key Inclusion Criteria:

Participants with histologically confirmed diagnosis of locally advanced unresectable or metastatic gastric, GEJ, or esophageal adenocarcinoma with life expectancy ≥3 months as assessed by the Investigator
Eastern cooperative oncology group (ECOG) Performance Score of 0-1
At least one measurable target lesion per RECIST v1.1.
Adequate organ and marrow function
Able to provide an archival tumor sample that is representative of the cancer under investigation and suitable for central immunotherapy-drugs-are-boosting-survival/" >PD-L1 testing

Key Exclusion Criteria:

Participants with underlying medical conditions that, in the Investigator's or Sponsor's opinion, will make the administration of investigational products hazardous
Only for Cohort A: Known Human Epidermal Growth Factor Receptor 2 (HER-2) positive tumor
Known untreated, symptomatic, or actively progressing central nervous system (brain) metastases. Participants with leptomeningeal metastases are excluded from enrollment.
Discontinued use of prior immune checkpoint therapy due to immune related adverse events; received prior treatment with an anti-TIGIT monoclonal antibody.
History of trauma or major surgery within 28 days prior to enrollment.

Note: Other protocol defined Inclusion/Exclusion criteria may apply.