The first reports of cancer overexpressing this transmembrane glycoprotein and its ligand (PD-L1) date back to 2002 on a mice population: PD1-high tumor cells showed enhanced invasiveness and they were immune to cytotoxic T cells lysis, but both effects resulted reversible by the administration of anti-PD-L1 antibodies [96]. Here, PDCD1 is linked to cancer.