IDH1 and glioblastoma: Glioblastoma (GBM) comprises 54% of all gliomas and is the most malignant primary brain tumor in adults, currently classified as adult-type diffuse isocitrate dehydrogenase (IDH)-wildtype glioma, or grade 4 according to the fifth WHO (World Health Organization) classification of tumors of the central nervous system (WHO CNS5) (Louis et al., 2021).