CD8A and neoplasm: AT3‐OVA tumours in mice treated with PTPN2‐deficient OT‐1 CD8+ T cells started to re‐emerge after 21 days, but survival was prolonged for as long as 86 days (Fig 2D; Appendix Fig S3H); by contrast, control mice achieved the maximum ethically permissible tumour burden (200 mm2) by 25 days.