Most of the current FMS-like tyrosine kinase 3 (FLT3) inhibitors lack selectivity between FLT3 kinase and cKIT kinase as well as the FLT3 wt and internal tandem duplication (ITD) mutants. We report a new compound 27, which displays GI<sub>50</sub> values of 30-80 nM against different ITD mutants and achieves selectivity over both FLT3 wt (8-fold) and cKIT kinase in the transformed BaF3 cells (>300-fold). 27 potently inhibits the proliferation of the FLT3-ITD-positive acute myeloid leukemia cancer lines through suppression of the phosphorylation of FLT3 kinase and downstream signaling pathways, induction of apoptosis, and arresting the cell cycle into the G0/G1 phase. 27 also displays potent antiproliferative effect against FLT3-ITD-positive patient primary cells, whereas it does not apparently affect FLT3 wt primary cells. In addition, it also exhibits a good therapeutic window to PBMC compared to PKC412. In the in vivo studies, 27 demonstrates favorable PK profiles and suppresses the tumor growth in the MV4-11 cell inoculated mouse xenograft model.