CD8+ T cell exhaustion is currently a major obstacle to anti-tumour immunotherapies, and in-depth studies of these cells in cancer have defined a four-stage developmental framework: Texprog1 (quiescent), Texprog2 (proliferative), Texint (moderately cytotoxic), and Texterm (terminally exhausted), and PD-1 pathway blockade has been shown to preferentially amplify Texprog2 and Texint subpopulations [34]. The gene discussed is CD8A; the disease is cancer.