PDCD1 and central nervous system cancer: Given the important role of ICIs in diverse cancers (André et al., 2020; Cacciotti et al., 2020; Ott et al., 2020), we further analyzed all immune checkpoints in glioma and found that most of those immune checkpoints, such as PD-1, PD-L1, PD-L2, CTLA4, and TIM3, were significantly different between the two risk groups (Figure 12).