Among all the inhibitory immune mediators, the pathway consisting of the programmed cell death protein 1 (PD-1) and its ligands PD-L1 (B7-H1, CD274) and PD-L2 (B7-DC, CD273) [3] has become a relevant tool for the great development that current cancer immunotherapy has achieved in recent years. Here, PDCD1 is linked to cancer.