PDCD1 and neoplasm: Immune checkpoint inhibitors (ICIs) targeting cytotoxic T lymphocyte-associated protein 4 (CTLA4), programmed cell death-1 (PD-1), and programmed cell death ligand-1 (PD-L1) have shown promising efficacy in certain tumor types, leading to their entry into the clinic (Gaynor et al. 2022).