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 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.