Inhibition of the NAD+ synthesis enzyme nicotinamide phosphoribosyl transferase (NAMPT) with FK866 and GMX1778 [30] or activation of the NAD+ consuming enzyme sirtuin (SIRT) with SIRT1-activating compounds, or a combination thereof, reduce cellular NAD+ levels and inhibit the growth of IDH1-mutant tumor cells [31]. The gene discussed is IDH1; the disease is neoplasm.