In vitro activity: BMS265246 inhibits the activity of CDK4/cycD with IC50 of 0.23 μM and prevents A2780 Cytox with IC50 of 0.76 μM. BMS265246 which binds to CDK2 shows the inhibitor resides coincident with the ATP purine binding site and forms important H-bonds with Leu83 on the protein backbone. BMS265246 exhibits CDK1 and CDK2 potency that is 25- and 11-fold more potent versus CDK1 and CDK2, respectively. BMS265246 represents the most potent CDK/CDK2 selective analogue from this chemotype. A recent study shows that BMS-265246 inhibits cell proliferation with EC50 ranging from 0.293 μM-0.492 μM in HCT-116 cells. After treatment of BMS-265246, the dominant cell populations are G2-arrested cells having 4N DNA content, large round nuclei, and low DNA intensity.

Kinase Assay: Kinase reactions consists of 100 ng of baculovirus expressed GST-CDK1/cyclin B1 complex, 1 μg histone H1, 0.2 μCi 33P γ-ATP, 25 μM ATP in 50 μL of kinase buffer (50 mM Tris, pH 8.0, 10 mM MgCl2, 1 mM EGTA, 0.5 mM DTT). Reactions are incubated for 45 min at 30 °C and stopped by the addition of cold trichloroacetic acid (TCA) to a final concentration of 15%. TCA precipitates are collected onto GF/C unifilter plates using a Filtermate universal harvester, and the filters are quantitated using a TopCount 96 well liquid scintillation counter. Dose response curves are generated to determine the concentration required to inhibit 50% of kinase activity (IC50). BMS265246 is dissolved at 10 mM in DMSO and evaluated at six concentrations, each in triplicate. The final concentration of DMSO in the assay equals 2%. IC50 values are derived by nonlinear regression analysis and have a coefficient of variance (SD/mean, n = 6) = 16%.

Cell Assay: HCT-116 cells are plated onto 96-well dishes. For each well, the cell density is calculated by counting the number of objects (cells) per field of view, and averaging across all fields for a given well. For a treatment compound, cell density is converted to a percentage relative to the plate-averaged cell density from DMSO treatment (i.e., 100% corresponds to the average cell density for DMSO treatment). Logistic regression curve fits are done using TIBCO Spotfire, and the concentration at which the curve crosses 50% is reported as the EC50 of BMS-265246.

Bioorg Med Chem Lett. 2003 Jul 21;13(14):2405-8; Mol Cancer Ther. 2011 Feb;10(2):242-54.