CD8A and neoplasm: The self‐tolerance developed in tumour microenvironment overtime dampens the therapeutic effect of T cell responses against tumours, but tumour‐derived exosomes can induce CD8+ T cell suppressors against tumours (Maybruck et al., 2017), increase regulatory T cells resistance to apoptosis and up‐regulate their suppressor functions (Szajnik et al., 2010).