Targeted immunotherapies and most prominently immune checkpoint blockade (ICB) therapies, brought clinical benefits to tumour patients that were inconceivable 15 years ago.2 These ICBs target inhibitory receptors such as PD-1 on tumour infiltrating CD8+ cytotoxic T lymphocytes (CTLs) that can recognise mutated cancer cell antigens and thereby enable tumour cell killing. The gene discussed is CD8A; the disease is cancer.