Many studies highlight the fact that colo-rectal cancer has immunogenic properties and that host immune responses can influence survival. Recent data have provided a clearer understanding of the factors limiting the antitumor immune response in colo-rectal cancer. One of the most critical checkpoint pathways responsible for mediating tumor-induced immune suppression is the programmed death-1 (PD-1) and PD ligand 1 (PD-L1) pathway.