PDCD1 and cancer: Clinical trials have repeatedly demonstrated the overall survival (OS) benefits of ICIs in patients with cancer of various types, and health authorities worldwide have granted regular approval for several ICIs, including a cytotoxic T‐lymphocyte antigen 4 (CTLA4) inhibitor (ipilimumab); programmed cell death 1 (PD‐1) inhibitors (cemiplimab, dostarlimab, nivolumab, and pembrolizumab); and programmed cell death ligand 1 (PD‐L1) inhibitors (atezolizumab, avelumab, and durvalumab).