CHEMBL5732044

RET G810R Mutant Assay: The potency of a compound inhibiting G81 OR mutant RET kinase was determined using CisBio's HTRF Kinease-TK assay technology. The assays contained G810R mutant RET produced at Array Biopharma, Inc. (1 nM enzyme p1982 Lot. No. 160713. The kinase was incubated with 250 nM TK-substrate biotin (CisBio, part of Catalog #62TK0PEC) and 1 mM ATP along with test compound in a buffer consisting of 25 mM HEPES, pH 7.4, 10 mM MgCl2, 0.01% Triton X-100, and 2% DMSO in a volume of 8 μL. Compounds were typically prepared as a threefold serial dilution in DMSO and added to the assay to give the appropriate final concentration. After a 60-min incubation at 22° C., the reaction was quenched by adding 8 μL of quench solution containing 31.25 nM Sa-XL665 and 1× TK-Ab-Cryptate in HTRF detection buffer (all from CisBio, part of cat #62TK0PEC). After a 1-h incubation at 22° C., the extent of reaction was determined using a PerkinElmer EnVision multimode plate reader via HTRF dual wavelength detection, and the percent of control (POC) was calculated using a ratiometric emission factor. One hundred POC was determined using no test compounds, and 0 POC was determined using pre-quenched control reactions. A 4-parameter logistic curve was fit to the POC values as a function of the concentration of compound, and the IC50 value was the point where the best-fit curve crossed 50 POC.