In vitro activity: SKLB4771 (also known as FLT3-IN-1) is a novel, potent and selective inhibitor of FLT3 (fms-like tyrosine kinase 3) that may be potentially used for the treatment of cutaneous inflammation and psoriasis-like symptoms of disease. SKLB4771 inhibited FLT3 phosphorylation dose-dependently. Consistent with the downregulation of the phosphorylation of FLT3, the phosphorylation of the downstream signaling proteins STAT5 and ERK1/2 was also significantly inhibited at concentrations>0.1 μM.

Kinase Assay: SKLB4771 inhibited FLT3 phosphorylation in a dose-dependent manner. Consistent with the downregulation of the phosphorylation of FLT3, the phosphorylation of the downstream signaling proteins STAT5 and ERK1/2 was also significantly inhibited at concentrations>0.1 μM. S

Cell Assay: KLB4771 potently inhibited the growth of MV4-11 cells that express FLT3-ITD, with an IC50 value of 0.006 μM. It just exhibited 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). For other leukemia and solid tumor cell lines, including K562, U937, Karpas299, HCC827, A549, H2228, H820, MDA-MB-231, BT474, MCF-7, HCT116, SW480, LoVo, HeLa, SKOV-3, SK, DU145, PC-3, A431, and SH-SY5Y .