Fig. 5.

NAMPT inhibitors demonstrate potent in vitro cytotoxicity in cells from ALL patient-derived xenografts through NAD+ depletion. (a) Viability curves. Samples were incubated for 48 h with each of three NAMPT inhibitors or doxorubicin (DOX), then analysed for viability by ATP assay. Each data point represents the mean and standard deviation of three technical replicates. (b) Summary of IC₅₀ values. FK866 demonstrated the lowest IC₅₀ in all five samples. Effects of NAD pre-treatment on (c) apoptosis. Patient samples 22763, 2003, 1995, or 105127-R were pre-treated with water or 100 µM NAD+ for one hour, then incubated with FK866 or DOX for 72 h for Annexin V/PI analysis. NAD+ completely prevented increases in mean (plus or minus standard deviation) apoptosis in FK866- but not DOX-treated patient samples. Experiments were performed with triplicate wells. Differences between groups were calculated with two-way ANOVA and Side's multiple comparisons test (*p < 0•05, **p < 0•001).