In vitro cytotoxic response of primary AML blasts to single-agent lestaurtinib and PKC412. (A) MTS assay dose-response curves showing mean cytotoxic response of 65 patient samples, grouped according to FLT3 mutation status, to lestaurtinib and PKC412, normalized to untreated controls. Error bars represent standard error of the mean (SEM). P values refer to statistical comparison of the FLT3 ITD and WT groups at each dose using the Student t test (only significant P values [P < .05] shown). (B) Dot plots showing the range of individual patient in vitro MTS IC₅₀ values for lestaurtinib and PKC412. The median and quartiles for each mutation group are indicated. P values refer to intergroup statistical analysis of log-transformed data by the Student t test, with significant differences in lestaurtinib IC₅₀ distribution being seen between WT and ITD cases and between WT cases and all FLT3 mutants grouped together. No significant group differences were seen with PKC412. (C) MTS assay dose-response curves showing mean cytotoxic response of 21 ITD samples to lestaurtinib and PKC412, grouped according to percentage FLT3 ITD RNA.