Structure-based discovery of cellular-active allosteric inhibitors of FAK.

Abstract In order to develop potent and selective focal adhesion kinase (FAK) inhibitors, synthetic studies on pyrazolo[4,3- c ][2,1]benzothiazines targeted for the FAK allosteric site were carried out. Based on the X-ray structural analysis of the co-crystal of the lead compound, 8-(4-ethylphenyl)-5-methyl-1,5-dihydropyrazolo[4,3- c ][2,1]benzothiazine 4,4-dioxide 1 with FAK, we designed and prepared 1,5-dimethyl-1,5-dihydropyrazolo[4,3- c ][2,1]benzothiazin derivatives which selectively inhibited kinase activity of FAK without affecting seven other kinases. The optimized compound, N -(4- tert -butylbenzyl)-1,5-dimethyl-1,5-dihydropyrazolo[4,3- c ][2,1]benzothiazin-8-amine 4,4-dioxide 30 possessed significant FAK kinase inhibitory activities both in cell-free (IC 50  = 0.64 μM) and in cellular assays (IC 50  = 7.1 μM). These results clearly demonstrated a potential of FAK allosteric inhibitors as antitumor agents.