Potent and selective BTK inhibitor (IC50= 0.5 nM). Selective for BTK against a screening panel of kinase enzymes. Inhibits autophosphorylation of BTK, phosphorylation of PLCγ, and phosphorylation of ERK (IC50 of 11 nM, 29 nM and 13 nM, respectively). Induces cytotoxicity of chronic lymphocytic leukemia (CLL) cells. Reduces clinical arthritis scores in a mouse model. Purity 98%. MW (observed): 440.5