Part I Role of the Tumor Microenvironment -- An Overview of the Tumor Microenvironment and Response to Immunotherapy in Gastrointestinal Malignancies -- Part II Esophagus -- Approach to Immunotherapy in Oesophageal Cancer -- Perspective on the Immunotherapy of Esophageal Cancer -- Part III Stomach -- Immunotherapy of Gastric Cancer: Focus on Perioperative Strategies -- Stomach: The Standard of Care ± HER2 -- Perspective on the Immunotherapy of Gastric Cancer -- Part IV Colon -- Immunotherapy in dMMR/MSI-H Colon Cancer -- Immunotherapy in the Treatment of Advanced Colorectal Cancer -- Immunotherapy of Rectal Cancer -- Perspective on Immunotherapy of Colon Cancer: Challenges for the Future -- Part V HCC -- Immune Strategies for Gastrointestinal Cancer: HCC -- Immunotherapy in GI Cancers: Hepatocellular Carcinoma: Perspective -- Part VI Biliary Tract -- Immunotherapy of Biliary Tract Cancer -- Perspective on Immunotherapy Use in Biliary Tract Cancer -- Part VII Pancreas -- Immune Landscape of Pancreas Ductal Adenocarcinoma: Current Therapeutic Strategies and Future Perspective -- Perspective on the Immunotherapy of Pancreatic Cancer -- Part VIII Biomarkers for Immunotherapy in Gastrointestinal Cancers -- Biomarkers for Immunotherapy in Gastrointestinal Cancers.