In vitro activity: AMG 925 inhibits cell growth (IC50 values of 19nM and 18nM, respectively) through inhibiting P-FLT3 and P-STAT5 and inducing apoptosis. FLT3 mutants cause resistance to the current FLT3 inhibitors. AMG 925 is reported to inhibit cell growth in AML cells with FLT3 mutants FLT3-D835Y and FLT3-D835V.

Kinase Assay: AMG 925 also inhibits CDK6, CDK2, and CDK1 in kinase assays with IC50s of 8±2 nM, 375±150 nM, 1.90±0.51 μM, respectively. A fair overall kinase selectivity of AMG 925 is as determined by KinomScan against a panel of 442 various kinases.

Cell Assay: MOLM13 and Mv4-11 are used. MOLM13-Luc cells are constructed by transduction of MOLM13 cells with the pLV218G luciferin/lentivector, which expresses luciferase under the murine EF1α promoter. Sorafenib-resistant MOLM13 (MOLM13sr) and Mv4-11 (Mv4-11sr) are isolated by passaging the cells in growth medium containing increasing concentrations of Sorafenib (1-1 nM). Cell growth is measured by a DNA synthesis assay. Cells are seeded in a 96-well Cytostar T plate at a density of 5×103 cells/well in a total volume of 160 μL. Test compounds (e.g., AMG 925; 0.03 and 0.3μM) are serially diluted into the plate (20 μL/well) and 20 μL/0.1 μCi of [14C]-Thymidine added to each well. Isotope incorporation is determined using a β plate counter after further 72-hour incubation. Apoptosis is assayed by using the Vybrant Apoptosis Assay Kit. Briefly, cells are seeded into a 6-well plate at 5×105 cells per well and treated with compounds (e.g., AMG 925; 0.003, 0.01, 0.03, 0.1, 0.3, and 1 μM) for 24 hours. The cells are then stained with reagents provided in the kit and analyzed by flow cytometry. The Sytox Green fluorescence versus allophycocyanin fluorescence dot plot shows resolution of live, apoptotic, and dead cells, which are quantified using the Flowjo software. The cell-cycle analysis is done by treating the cells with AMG 925 for 24 hours followed by using the CycleTest Kit. Ten thousand events are acquired and the proportions of cells in each cycle phase are calculated using the ModFit software