AZD6482

The inhibition of PI3Kβ, PI3Kα, PI3Kγ, and PI3Kδ is evaluated in an AlphaScreen based enzyme activity assay using human recombinant enzymes. The assay measures PI3K-mediated conversion of PIP2 to PIP3. Biotinylated PIP3, a GST-tagged pleckstrin homology (PH) domain and the two AlphaScreen beads form a complex that elicits a signal upon laser excitation at 680 nm. The PIP3 formed in the enzyme reaction competes with the biotinylated PIP3 for binding to the PH domain thus reducing the signal with increasing enzyme product. The AZD6482 is dissolved in DMSO and added to 384 well plates. PBKβ, PBKα, PBKγ, or PBKδ is added in a Tris buffer (50 mM Tris pH 7.6, 0.05% CHAPS, 5 mM DTT, and 24 mM MgCl₂) and allowed to preincubate with AZD6482 for 20 minutes prior to the addition of substrate solution containing PIP2 and ATP. The enzyme reaction is stopped after 20 minutes by addition of stop solution containing EDTA and biotin-PIP3, followed by addition of detection solution containing GST-grpl PH and AlphaScreen beads. Plates are left for a minimum of 5 hours in the dark prior to analysis. The final concentration of DMSO, ATP and PIP2 in the assay are, 0.8%, 4 μM, and 40 μM, respectively. IC50 values are calculated according to the equation, y = {a+[(b-a)/(l+(x/IC50)^s)]}, where y = % inhibition; a = 0%; b = 100%; s = the slope of the concentration-response curve; x = AZD6482 concentration.

Human platelet pellet

0–60 nM, dissolved in DMSO

5 min

For assay of washed platelet aggregation (WPA), the platelet pellets are isolated from human blood and re-suspended to 2 × 10¹⁵/L in Tyrodes buffer (TB) containing 1 μM hirudin and 0.02 U/mL apyrase. Then, the platelet suspension is left to rest at room temperature for 30 min. Just prior to time for assay, CaCl₂ is added to a final concentration of 2 mM. AZD6482, dissolved in DMSO, is added to a 96-well plate prior to the addition of the washed platelet suspension. The platelet suspension is preincubated with AZD6482 for 5 min. Light absorption at 650 nm is recorded before and after a 5 min plate shake and referred to as recording 0 (R0) and Rl. A mouse anti-human CD9 antibody is added (at a donor specific concentration) to each well prior to next 10 min plate shake and light absorption recording; R2. For data analysis, light absorbance in wells with TB are subtracted from all readings before percent aggregation is calculated according the formula: [(R1-R2)/R1] × 100 = % aggregation. Spontaneous aggregation or pro-aggregatory effect of the inhibitor is evaluated by the same formula, [(R0-Rl)/R0] × 100 = % aggregation. IC50 values are calculated according to the equation, y = {a+[(b-a)/(l+(x/IC50)^s)]}, where y = % inhibition; a = 0%; b = 100%; s = the slope of the concentration-response curve; x = AZD6482 concentration.