One of the most successful ICIs targets the programmed cell death 1 (PD‐1) molecule, a key checkpoint on T‐cells which dampens responses (including proliferation, cytokine production and cytotoxicity) when bound to programmed death ligand 1 (PD‐L1) or PD‐L2 on tumour cells (Patsoukis et al., 2020). The gene discussed is PDCD1; the disease is neoplasm.