Currently, immunotherapy is considered as the fourth major modality of cancer treatment except surgery, chemotherapy and radiotherapy. The new therapeutic approach based on immune checkpoint inhibitors is a landmark innovation. Strategies considering checkpoint inhibitors have shown good anti-tumor effect by targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1) or programmed cell death ligand 1 (PD-L1). Moreover, DNA mismatch repair-deficient tumors appear to be potential candidates for these therapies. This review summarizes the discussion and oral presentations in the annual meeting of American Society of Clinical Oncology (ASCO) and ASCO-gastrointestinal cancer (GI) in 2016 and provides an update on immunotherapy in gastrointestinal cancers.