FLT3-IN-12 is a potent, selective and orally active FLT3 kinase inhibitor with IC 50 s of 1.48 nM and 2.87 nM for FLT3-WT and FLT3-D835Y , respectively. FLT3-IN-12 possesses high selectivity over c-KIT (>1000-fold). FLT3-IN-12 has an excellent anti-AML (acute myeloid leukemia) activity (MV4-11, IC 50 of 0.75 nM).