IDH1 and glioblastoma: For the astrocytic glioma/glioblastoma, IDH-mutant cluster, independent of WHO grade, there is a significant overall survival difference across the M1–M3 molecular subtypes (p < 0.001, Cox proportional hazards regression, Fig. 7b), with median survivals of 23.3 months (M1), 63.0 months (M2) and 94.5 months (M3).