Discovery of pyrazolo[1,5-a]pyridines as p110α-selective PI3 kinase inhibitors

We have made a novel series of pyrazolo[1,5-a]pyridines as PI3 kinase inhibitors, and demonstrated their selectivity for the p110 alpha isoform over the other Class Ia PI3 kinases. We investigated the SAR around the pyrazolo[1,5-a] pyridine ring system, and found compound 5x to be a particularly potent example (p110 alpha IC50 0.9 nM). This compound inhibits cell proliferation and phosphorylation of Akt/PKB, a downstream marker of PI3 kinase activity, and showed in vivo activity in an HCT-116 human xenograft model. (C) 2011 Elsevier Ltd. All rights reserved.