CNX-774 is a highly specific, irreversible, and orally active BTK inhibitor (IC50<1 nM).

BTK:<1 nM

In a cellular assay, CNX-774 targeted residue Cys-481, the ATP-binding site of BTK, thereby inhibiting its activity (IC50: 1-10 nM).

In vitro kinase assays: The p38α and p38β are assayed in 25 mM Tris-HCl, pH 7.5, containing 0.1 mM EGTA, with myelin basic protein (0.33 mg/mL) as substrate. Assays are performed either manually for 10 minutes at 30 °C in 50 μL incubations using [γ-33P]ATP, or with a Biomek 2000 Laboratory Automation Workstation in a 96-well format for 40 minutes at ambient temperature in 25 μL incubations using [γ-33P]ATP. The concentrations of ATP and magnesium acetate are 0.1 mM and 10 mM respectively. All assays are initiated with MgATP. Manual assays are terminated by spotting aliquots of incubation on to phosphocellulose paper, followed by immersion in 50 mM phosphoric acid. Robotic assays are terminated by the addition of 5 μL of 0.5 M phosphoric acid before spotting aliquots on to P30 filter mats. All papers are then washed four times in 50 mM phosphoric acid to remove ATP, once in acetone (manual incubations) or methanol (robotic incubations), and then dried and counted for radioactivity.