Checkpoint inhibitors (such as programmed cell death protein 1 (PD‐1) or Cytotoxic T‐Lymphocyte Associated protein 4 (CTLA‐4) inhibitors) present one avenue of immunotherapy that aim to circumvent the immunosuppression inherent to many cancers and thus, enable immune cells to carry out their ‘anti‐tumour’ roles.2 This evidence concerns the gene PDCD1 and neoplasm.