Finally, it is important to note that the associations of perfusion, diffusion, and volumetric MRI metrics with PFS in this limited patient cohort are not reflective of any potential benefit of IDH inhibitor therapy (see commentary on survival by tumor response by Anderson and Gelber49) in IDH1-mutant gliomas, but simply reflect patient stratifications based on radiographic assessment within patients treated with IDH inhibitors. This evidence concerns the gene IDH1 and central nervous system cancer.