A Study to Evaluate Immunotherapy Combinations in Participants With Gastrointestinal Malignancies

This is a Phase 1/1b, open-label, dose-escalation, and dose-expansion study to evaluate the safety, tolerability, pharmacokinetic (PK), pharmacodynamic (PD), and clinical activity of etrumadenant (AB928) in combination with mFOLFOX in participants with advanced metastatic gastroesophageal Cancer (GEC) or colorectal cancer (CRC).