Epithelial ovarian cancers that develop in patients with BRCA (germline and somatic) mutations have been shown to have a higher mutational load, leading to an increase in the number of neoantigens and to higher levels in tumour-infiltrating lymphocytes, CD3+ and CD8+ counts and higher levels of PD-1 and PD-L1.46,47 This group of patients may therefore derive increased benefit from immune checkpoint inhibitors, either as single-agent therapy or in combination with PARP inhibitors or chemotherapy. The gene discussed is CD8A; the disease is ovarian carcinoma.