HHT and IPI50 inhibit the growth of primary AML cells. (A and B) The FLT3-ITD (+) primary AML cells and (C and D) FLT3-wild type primary AML cells were treated with HHT, IPI504 and HHT+IPI504 for 48 h. The rate of cell viability was measured by MTT assay. (E) The combination index (CI) values of 18 patient samples at the ED50, ED75 and ED90 were showed (FLT3-ITD (+) n= 7; FLT3-wt n=11, solid bars represent the mean CI values for each group). The CI values were calculated by Calcusyn according to the median effect method of Chou and Talalay [21]. (mean ± SEM, n=3, *P < .05, **P < .01, ***P < .001)