IDH1 and central nervous system cancer: in 2020, who showed upregulation of PD‐1 expression in IDH‐mutant GBM (current nomenclature is WHO grade IV IDH‐mutant astrocytoma) and IDH‐wildtype GBM, based on their analysis of PD‐1 transcriptional expression data of 1323 glioma from the CGGA and TCGA datasets and a local hospital cohort.