Indeed, T cell exhaustion was first described in the context of chronic infections.7 8 In the following, T lymphocytes with a similar phenotype were also detected in the tumor microenvironment.2 7–9 Exhausted T lymphocytes are functionally characterized by a loss of interleukin 2 (IL-2) production, impaired proliferation, diminished cytotoxicity, and altered production of proinflammatory cytokines.2 7–9 Moreover, the overexpression of immune checkpoint receptors, including PD-1 and CTLA-4, is a characteristic. This evidence concerns the gene PDCD1 and neoplasm.