Gastric cancer (GC) is a major world-wide health problem. It is the third 
leading cause of death from cancer. The treatment of advanced GC by chemotherapy 
has limited efficacy. The addition of some targeted therapies like trastuzumab 
and ramucirumab have added a modest benefit, but only in human epidermal growth 
factor receptor 2 (ERBB2 or HER2)-positive patients and in the second-line 
setting, respectively. The development of new and effective therapeutic 
strategies must consider the genetic complexity and heterogeneity of GC; 
prognostic and predictive biomarkers should be identified for clinical 
implementation. Immune deregulation has been associated with some GC subtypes, 
especially those that are associated with virus infection and those with a high 
mutational rate. Different mechanisms to prevent immunologic escape have been 
characterized during the last years; in particular the PD-1/PD-L1 inhibitors 
pembrolizumab, avelumab, durvalumab and atezolizumab have shown early sign of 
efficacy. Therefore, immunotherapeutic strategies may provide new opportunities 
for GC patients. This review will discuss (1) the main characteristics of GC 
treatment, (2) the immune response in GC, and (3) the current status of 
immune-related strategies in clinical development in GC patients, focusing on 
immune checkpoints therapies.