Cytotoxicity assays of FLT3/ITD primary AML samples. Peripheral blood blasts isolated from 13 patients with AML harboring FLT3/ITD mutations were incubated in increasing concentrations of each of the 5 FLT3 inhibitors indicated and analyzed using the MTT assay as described in “Cytotoxicity assays.” The experiment was repeated, and the data from both experiments was combined. (A) Dose-response curves for a single FLT3/ITD sample (No. 10 from Table 2) exposed to each of 5 FLT3 inhibitors. Error bars represent standard deviations. (B) Composite dose-response curves for all 5 inhibitors and all 13 FLT3/ITD samples. For each drug concentration, the percentage control for all 13 samples was expressed as a mean value, with error bars representing the SEMs. Each individual data point on these curves represents the mean of roughly 7 OD values for each of 13 different AML samples (ie, 7 × 13 = 91 OD values). (C) Composite dose-response curves for 14 wild-type FLT3 samples exposed to sunitinib (top curve) or lestaurtinib (middle curve).