Inhibition of mouse PI3K alpha expressed in insect cells coexpressing p85 subunit assessed as PI(3,4,5)P3 formation using PI(4,5)P2 as substrate by measuring displacement of TAMRA-labeled PI(3,4,5)P3 from Grip1 PH domain after 35 mins by ligand displacement fluorescence polarization assay
Drug metabolism in iv dosed rat plasma assessed as 2-amino-8-((trans)-4-hydroxycyclohexyl)-6-(6-methoxypyridin-3-yl)-4-methylpyrido[2,3-d]pyrimidin-7(8H)-one level
Drug metabolism in po dosed mouse plasma assessed as 2-amino-8-((trans)-4-hydroxycyclohexyl)-6-(6-methoxypyridin-3-yl)-4-methylpyrido[2,3-d]pyrimidin-7(8H)-one level
Biochemical Assay: Compounds of the present invention were evaluated for potency against PI3-Kα using an in vitro kinase assay. PI3-Kα activity is measured in vitro by determining the level of phosphorylation of the substrate PI(4,5)P2. The formation of product PI(3,4,5)P3 is monitored by binding to the Grip1 PH domain in a ligand displacement fluorescence polarization (FP) assay, in which the TAMRA-labeled PI(3,4,5)P3 complexed with Grip1 PH domain is displaced by PI(3,4,5)P3 formed in the PI3-Kα reaction resulting in a decrease in FP signal.