FLT3-IN-20 (compound 34f) is a potent FLT3 inhibitor with IC 50 values of 1 and 4 nM for FLT3-D835Y and FLT3-ITD, respectively. FLT3-IN-20 has anti-proliferation efficacy in FLT3-ITD-positive AML cell lines MV4-11 and MOLM-13 (7 and 9 nM, respectively) and the MOLM-13 variant (4 nM) with the FLT3-ITD-D835Y mutation. FLT3-IN-20 can be used in research of cancer.