PDCD1 and cancer: Since the anti-CTLA-4 inhibitor ipilimumab was approved for the management of advanced melanoma,9 immune checkpoint inhibitors (ICIs), such as anti-cytotoxic T lymphocyte associated antigen 4 (CTLA-4) and anti-programmed cell death protein-1 (PD-1)/programmed death-ligand-1 (PD-L1) antibodies, have led a paradigm shift in the management of advanced cancers.