In particular, GBM elicits severe T cell exhaustion among CD8+ TILs with prominent upregulation of inhibitory immune checkpoints PD-1, LAG-3, TIGIT, and CD39, and the function of TILs from murine GBM, such as the production of IFN-γ and IL-2, was impaired [47]. Here, IL2 is linked to glioblastoma.