The finding that those patients rendering TR TILs had a higher frequency of CD137+PD-1+CD8+ TILs located in the tumour epithelium, suggests that their tumours may have special features that have enabled the activation of T cells, e.g., the presence of relevant antigens or/and an immune-permissive tumour microenvironment (TME). The gene discussed is PDCD1; the disease is neoplasm.