FLT3/ITD-IN-2 (Compound 17) is a potent FLT3 internal tandem duplications ( FLT3-ITD ) inhibitor with IC 50 values of 0.3, 0.4 and 1.0 nM against FLT3 D835Y , FLT3 and FLT3-ITD, respectively. FLT3/ITD-IN-2 potently inhibits the phosphorylation of FLT3 and displays excellent antiproliferative activities against acute myeloid leukemia cell lines.