In vitro activity: AZD8330 potently and strongly inhibits MEK 1/2. AZD8330 has no inhibitory activity against over 200 other kinases including at concentrations up to 10 μM. AZD8330 demonstrates sub-nanomolar potency in mechanistic (pERK) and low to sub-nanomolar potency in functional (proliferation) assays in MEK 1/2 inhibitor sensitive cell lines.

Kinase Assay: NH2-terminal hexahistidine tagged, constitutively active MEK1 (S218D, S222D ΔR4F) is expressed in baculovirus-infected Hi5 insect cells and purified by immobilized metal affinity chromatography, ion exchange, and gel filtration. The activity of MEK1 is assessed by measuring the incorporation of [γ- 33P]phosphate from [γ-33P]ATP onto ERK2. The assay is carried out in a 96-well polypropylene plate with an incubation mixture (100 μL) composed of 25 mM HEPES (pH 7.4), 10 mM MgCl2, 5 mM β-glycerolphosphate, 100 μM sodium orthovanadate, 5 mM DTT, 5 nM MEK1, 1 μM ERK2, and 0 to 80 nM AZD8330 (final concentration of 1% DMSO). The reactions are initiated by the addition of 10 μM ATP (with 0.5 μC k[γ-33P]ATP/well) and incubated at room temperature for 45 min. An equal volume of 25% trichloracetic acid is added to stop the reaction and precipitate the proteins. Precipitated proteins are trapped onto glass fiber B filter plates, excess labeled ATP is washed off with 0.5% phosphoric acid, and radioactivity is counted in a liquid scintillation counter. ATP dependence is determined by varying the amount of ATP in the reaction mixture. The data are globally fitted.

Cell Assay: Malme-3M melanoma cells are plated in 96-wells and treated with various concentrations of AZD8330 for 1 hour at 37 °C. The cells are fixed, permeabilized, and incubated with an anti-phospho-ERK antibody and an anti-ERK 1/2 antibody. Plates are washed and fluorescently-labeled secondary antibodies are added. Plates are analyzed on a LICOR fluorescence imager. The pERK signal is normalized to the total ERK signal.

Clin Cancer Res. 2007 Mar 1;13(5):1576-83.