PDCD1 and cancer: Furthermore, reactivating CD8+ T cell immunity against tumours using targeted checkpoint blockade therapy has revolutionised cancer treatments and patient outcomes, subsequently leading to the Nobel Prize in Physiology and Medicine in 2018 being awarded to James Allison and Tasuku Honjo for their discovery of CTLA-4 (cytotoxic lymphocyte protein 4) and PD-1 (programmed cell death protein 1) [12,13].