PDCD1 and cancer: During the last few years, new therapies directed against molecular targets involved in the regulation of the immune homeostasis and cancer immunity have been incorporated, particularly immune checkpoint inhibitors (ICIs), such as monoclonal antibodies against the Programmed Cell Death Protein 1/Ligand 1 (PD1/L1) axes or Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4) (4).