Assay Method Information
Assay Name:  Exon20-mutant-EGFR(D770_N771insSVD) kinase assay
Description:   Inhibitory activity of compounds of the present invention against an Epidermal Growth Factor Receptor (EGFR) with an insertion of the amino acids sequence SVD between D770and N771 was quantified employing the TR-FRET based kinase activity assay as described in the following paragraphs.A recombinant fusion protein of N-terminal Glutathion-S-Transferase (GST) and a fragment of human EGFR variant (amino acids R669 to A1210 with insertion of the amino acids sequence SVD between D770 and N771 ( EGFR ins SVD ), expressed in Sf9 insect cells and purified via affinity chromatography using Glutathion Sepharose as described above, was used as a kinase. As substrate for the kinase reaction the biotinylated peptide biotin-Ahx-AEEEEYFELVAKKK (C-terminus in amide form) was used which can be purchased e.g. form the company Biosynthan GmbH (Berlin-Buch, Germany).For the assay 50 nl of a 100-fold concentrated solution of the test compound in DMSO was pipetted into either a black low volume 384 well microtiter plate or a black 1536 well microtiter plate (both Greiner Bio-One, Frickenhausen, Germany), 2 痞 of a solution of EGFR in aqueous assay buffer [50 mM Hepes pH 7.0, 10 mM MgCl2, 1 mM dithiothreitol, 0.5 mM EGTA, 0.3 mM activated sodium ortho-vanadate, 0.005% (w/v) bovine serum albumin, 0.005% (v/v) Tween-20] were added and the mixture was incubated for 15 min at 22蚓 to allow pre binding of the test compounds to the enzyme before the start of the kinase reaction. Then the kinase reaction was started by the addition of 3 無 of a solution of adenosine tri phosphate (ATP, 3.33 mM => final conc. in the 5 無 assay volume is 2 mM) and substrate (1.67 然 => final conc. in the 5 無 assay volume is 1 然) in assay buffer and the resulting mixture was incubated for a reaction time of 30 min at 22蚓. The concentration of EGFR was adjusted depending of the activity of the enzyme lot and was chosen appropriate to have the assay in the linear range, typical concentration was 15 pg/痞. The reaction was stopped by the addition of 3 痞 of a solution of HTRF detection reagents (83.3 nM streptavidine-XL665 [Cisbio Bioassays, Codolet, France] and 1.67 nM PT66-Tb-Cryptate, a terbium-cryptate labelled anti-phospho-tyrosine antibody from Cisbio Bioassays [instead of the PT66 Tb cryptate PT66 Eu Chelate from Perkin Elmer can also be used]) in an aqueous EDTA-solution (133.3 mM EDTA, 0.2% (w/v) bovine serum albumin in 50 mM HEPES pH 7.5). The resulting mixture was incubated 1 h at 22蚓 to allow the binding of the biotinylated phosphorylated peptide to the streptavidine-XL665 and the PT66-Tb-Cryptate. Subsequently the amount of phosphorylated substrate was evaluated by measurement of the resonance energy transfer from the PT66-Tb-Cryptate to the streptavidine-XL665. Therefore, the fluorescence emissions at 620 nm and 665 nm after excitation at 337 nm were measured in a HTRF reader, e.g. a Pherastar (BMG Labtechnologies, Offenburg, Germany) or a Viewlux (Perkin-Elmer). The ratio of the emissions at 665 nm and at 622 nm was taken as the measure for the amount of phosphorylated substrate. The data were normalised (enzyme reaction without inhibitor = 0% inhibition, all other assay components but no enzyme = 100% inhibition). Usually the test compounds were tested on the same microtiterplate in 11 different concentrations in the range of 20 然 to 0.07 nM (20 然, 5.7 然, 1.6 然, 0.47 然, 0.13 然, 38 nM, 11 nM, 3.1 nM, 0.9 nM, 0.25 nM and 0.07 nM, the dilution series prepared separately before the assay on the level of the 100fold concentrated solutions in DMSO by serial dilutions, exact concentrations may vary depending pipettors used) in duplicate values for each concentration and IC50 values were calculated using Genedata Screener software.
Affinity data for this assay
 
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