Of the 8 patients with secondary or low-grade glioma, 5 (5/8;62 %) had an isocitrate dehydrogenase (IDH) 1 or IDH2 mutation (Table 3), and 4 of these 5 showed clinical benefit, while none of the 3 low-grade or secondary gliomas without IDH mutations showed radiographic responses or SD ≥6 cycles. This evidence concerns the gene IDH2 and central nervous system cancer.