In an additional methylation analysis of the PD-L1 promoter region, a hypermethylation in IDH1/2 mutated patients was found (Figure 1C, 1D), possibly explaining the downregulation of PD-L1 expression in proneural glioblastoma, which are partly G-CIMP (Figure 1D). Here, IDH1 is linked to glioblastoma.