Five different IDH inhibitors are under evaluation in glioma patients, including the two IDH1 inhibitors AG-120 and AG-881, the IDH2 inhibitor AG-221, the pan-mutant IDH inhibitor BAY1436032, and the IDH1 inhibitor IDH-305 to be evaluated in phase 2 studies in grade II or III gliomas with IDH1 mutation that have progressed after observation or radiation therapy [404]. This evidence concerns the gene IDH2 and central nervous system cancer.