FLT3 and acute myeloid leukemia: The in vitro efficacy of tefinostat was first assessed by MTS cell viability assay in AML cell lines HL60 (M2 FAB type), MV411 (M4, FLT3-ITD), OCIAML3 (M4 NPM1mut) and THP1 (M5) (EC50 = 2300 nM +/−226 vs. 57 nM +/−6.2 vs. 110 nM +/− vs. 560 nM +/−17.12 respectively, Figure 1A).