On the one hand, imatinib brings meaningful immunologic benefit to GIST patients, such as augmentations of the infiltration and activity of CD8+ T cells, DC cells and NK cells, increases of IFNγ secretion, reductions in Treg cells infiltration [35, 95, 99, 113, 134, 136, 141, 169, 175, 191–194] and PD-L1 expression [35, 102], and thereby enhancing the antitumor immune responses. Here, CD8A is linked to gastrointestinal stromal tumor.