PDCD1 and glioblastoma: In this study, we utilized pathway-based gene expression data and performed unsupervised clustering to identify two distinct prognostic GBM subtypes: cluster 1 (C1-GBM), characterized by an enriched immune microenvironment and active PD1 and MHC pathways (immune-infiltrated “hot” tumors), and cluster 2 (C2-GBM), defined by activation of cell cycle and G2/M checkpoint (inherent driving).