Both the NAMPT inhibitors FK866 and GMX1778, potently inhibited cell viability of six endogenous IDH1/2-mut cancer cell lines, including three IDH1R132H-mut GBM TICs (MGG119, MGG152, and BT142), the IDH1R132C-mut lines HT1080 and 30T, SW1353 chondrosarcoma (IDH2R172S), with IC50 values ranging between 1 and 25 nM. This evidence concerns the gene IDH1 and chondrosarcoma.