SKLB4771 is a potent and selective inhibitor of human receptor-type tyrosine-protein kinase FLT3 with IC50 of 10?nM.
SKLB4771 just weakly inhibits Aurora A, FMS, FLT4, and c-Kit (IC50s: 1.5 μM, 2.8 μM, 3.7 μM, and 6.8 μM, respectively). SKLB4771 displays almost no inhibitory activity against the other 13 selected protein kinases. SKLB4771 potently inhibits the growth of MV4-11 cells that express FLT3-ITD, with an IC50 value of 0.006 μM. SKLB4771 just exhibits very weak inhibitory activity against human T lymphoma Jurkat cells, human Burkitt’s lymphoma Ramos cells, human lung cancer PC-9 and H292 cells, and human epithelial carcinoma A431 cells (IC50: 3.05 μM, 6.25 μM, 3.72 μM, 6.94 μM, and 8.91 μM, respectively).[1].
Treatment with SKLB4771 at 100 mg/ kg/d results in rapid and complete tumor regression in all mice of this group in the MV4-11 xenograft model. SKLB4771 treatment at 20 mg/kg/d and 40 mg/kg/d significantly slows down the tumor growth, the tumor inhibition rates are 66% and 84%,respectively. Moreover, during the whole experiment, no significant weight loss or any other obvious signs of toxicity are observed for all of the SKLB4771-treated mice. The tumor tissues from the SKLB4771-treated groups show significantly fewer Ki67(tumor mitotic index)-positive cells. The TUNEL data shows an obvious increase in the percentage of apoptotic cells in a time-dependent manner.[1]
[1] Li WW, et al. J Med Chem. 2012 26;55(8):3852-66.