Pilaralisib (XL-147) is an orally available small molecule that selectively inhibits the activity of phosphoinositide-3 kinase (PI3K). Pilaralisib has been used in trials studying the treatment of Cancer, Lymphoma, Solid Tumors, Glioblastoma, and Breast Cancer, among others.

PI3Kγ:23 nM, PI3Kα:39 nM, PI3Kβ:36 nM, PI3Kδ:36 nM

Pilaralisib exhibits cytotoxic activity in Pediatric PreClinicalal Testing Program (PPTP) cell lines, with a median relative IC50 value of 10.9 mM (range 2.7 mM to 24.5 mM).[2]

In BALB/c nu/nu mice, Pilaralisib (100 mg/kg, p.o.) induces tumor growth inhibition for solid glioma xenografts. Pilaralisib is well tolerated, with only 0.7% toxicity rate in the treated groups, similar to that observed for control animals.[2] In athymic female mouse, Pilaralisib (100 mg/kg, p.o.) significantly delays tumor growth without significant drug-related toxicity.[3]

In vitro kinase inhibition assays: Kinase activity for PI3K isoforms is measured as the percentage of ATP consumed following the kinase reaction using luciferase–luciferin-coupled chemiluminescence, with ATP concentrations approximately equal to the Km for each respective kinase. Kinase reactions are initiated by combining test compounds, ATP and kinase in a 20 μL volume. PI3Kα, PI3Kβ, PI3Kγ, and PI3Kδ final enzyme concentrations are 0.5, 8, 20, and 2 nM, respectively. Of note, 0.5 μL dimethyl sulfoxide (DMSO) containing varying concentrations of the test compound is mixed with 10 μL enzyme solution (2×concentration). Kinase reactions are initiated by the addition of 10 μL of liver phosphatidylinositol and ATP solution (2×concentration). Assay concentrations for VPS34, ATP, and phosphatidylinositol are 40 nM, 1 μM, and 5 μM, respectively

Cell proliferation is measured by using MTT or pre-mixed WST-1 reagent. For MTT/WST-1 assays, 10,000 cells/well are seeded in 96-well plates. 24 h after plating, cells are treated with DMSO or pilaralisib. After 5 days of treatment, MTT/WST-1 assays are performed.(Only for Reference)