Document Report Card

ID: ALA2176956

Journal: J Med Chem

Title: Application of structure-based drug design and parallel chemistry to identify selective, brain penetrant, in vivo active phosphodiesterase 9A inhibitors.

Authors: Claffey MM, Helal CJ, Verhoest PR, Kang Z, Fors KS, Jung S, Zhong J, Bundesmann MW, Hou X, Lui S, Kleiman RJ, Vanase-Frawley M, Schmidt AW, Menniti F, Schmidt CJ, Hoffman WE, Hajos M, McDowell L, O'Connor RE, Macdougall-Murphy M, Fonseca KR, Becker SL, Nelson FR, Liras S.

Abstract: Phosphodiesterase 9A inhibitors have shown activity in preclinical models of cognition with potential application as novel therapies for treating Alzheimer's disease. Our clinical candidate, PF-04447943 (2), demonstrated acceptable CNS permeability in rats with modest asymmetry between central and peripheral compartments (free brain/free plasma = 0.32; CSF/free plasma = 0.19) yet had physicochemical properties outside the range associated with traditional CNS drugs. To address the potential risk of restricted CNS penetration with 2 in human clinical trials, we sought to identify a preclinical candidate with no asymmetry in rat brain penetration and that could advance into development. Merging the medicinal chemistry strategies of structure-based design with parallel chemistry, a novel series of PDE9A inhibitors was identified that showed improved selectivity over PDE1C. Optimization afforded preclinical candidate 19 that demonstrated free brain/free plasma ≥ 1 in rat and reduced microsomal clearance along with the ability to increase cyclic guanosine monophosphosphate levels in rat CSF.

CiteXplore: 23025719

DOI: 10.1021/jm3009635