Study of Denikitug (GS-1811) Given Alone or With Nivolumab or Chemotherapy in Adults With Metastatic Gastric, Gastroesophageal Junction (GEJ), and Esophageal Adenocarcinomas

Exclusion Criteria

• •Active or history of autoimmune disease requiring systemic treatment within 2 years, IBD (Crohn's/ulcerative colitis), celiac disease, or noninfectious enteritis/colitis. (Physiologic hormone replacement not considered systemic treatment).
• •History or current noninfectious pneumonitis/interstitial lung disease, including radiation-induced pneumonitis requiring steroids or active/recurrent pneumonitis of any etiology.
• •Documented microsatellite instability-high (MSI-H) or deficient mismatch repair (dMMR) disease by local polymerase chain reaction (PCR) (microsatellite status) and/or informed consent form (ICH) (mismatch repair (MMR)) assay
• •(For Part 2 only) Has known history of peripheral neuropathy ≥ Grade 2 (per NCI-CTCAE Version 5.0).
• •(For Part 2 only) Known coagulopathy that increases the risk of bleeding, bleeding diatheses. Any other Grade 3 or higher hemorrhage/bleeding event within 28 days prior to enrollment.
• •Prior/Concurrent Therapy or Clinical Study Experience
• •Prior treatment with DEN or other C-C chemokine receptor 8 (CCR8)-targeted agents.
• •Prior Lonsurf (trifluridine-tipiracil) or paclitaxel (PAC)-based regimens in the first-line setting for advanced/metastatic gastroesophageal adenocarcinoma.
• •Any systemic therapy (including investigational) targeting vascular endothelial growth factor (VEGF) or VEGF receptor (VEGFR) signaling pathways.
• •Anticancer biologic within 4 weeks, orchemotherapy, targeted small molecule, or radiation therapy within 2 weeks prior to enrollment with unresolved AEs (Grade \>2). (Observational study participants are eligible).
• •Prior allogenic tissue/solid organ or stem cell transplantation. (Exception: corneal transplant not requiring systemic immunosuppression is allowed).