KinomeScan kinase binding assays are performed. For the FLT3 assay, a kinase construct that spanned the catalytic domain only (amino acids 592 to 969) is used. This construct does not include the juxtamembrane domain and is designed to measure the intrinsic binding affinity of the open FLT3 active site for inhibitors^[1].

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

MV4-11 and RS4;11 cells are cultured in Iscove media with 10% fetal bovine serum (FBS) and RPMI complete with 10% FBS, respectively. For proliferation assays, cells are cultured overnight in low serum media (0.5% FBS), then seeded in a 96-well plate at 40 000 cells per well. Inhibitors (e.g., Quizartinib) are added to the cells and incubated at 37°C for 72 hours. Cell viability is measured using the Cell Titer-Blue Cell Viability Assay. To measure inhibition of FLT3 autophosphorylation, cells are cultured in low serum media (0.5% FBS) overnight and seeded at a density of 400 000 cells per well in a 96-well plate the following day. The cells are incubated with inhibitors (e.g., Quizartinib) for 2 hours at 37°C. To induce FLT3 autophosphorylation in RS4;11 cells, 100 ng/mL FLT3 ligand is added for 15 minutes after the 2-hour compound incubation. Cell lysates are prepared and incubated in 96-well plates precoated with a total FLT3 capture antibody. The coated plates are incubated with either a biotinylated antibody against FLT3 to detect total FLT3 or an antibody against phosphotyrosines to detect FLT3 autophosphorylation. In both cases, a SULFO-tagged streptavidin secondary antibody is used for electrochemiluminescence detection on the Meso Scale Discovery platform^[1].

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

Mice^[1]
Female NU/NU or severe combined immunodeficient mice are used. Quizartinib (hydrochloride salt) is formulated in 22% hydroxypropyl-β-cyclodextrin, CEP-701 is formulated in 20% gelucire 44/14 in water (vol/vol), MLN-518 and SU 11248 are formulated in 10 mM sodium citrate (pH 3.5), PKC-412 is formulated in 3:1 gelucire 44/14-propylene glycol (vol/vol), and Bay 43-9006 is formulated in 80% PEG-400. Compound concentrations are chosen to deliver the desired dose in a volume of 10 mL/kg. Compounds are administered by oral gavage and plasma samples collected 0.25, 0.5, 1, 2, 4, 6, and 24 hours after dosing. To collect plasma samples, eye bleeds (150 μL) are taken semilongitudinally using 3 groups of 3 animals each, taking 2 to 3 time points per animal to obtain a total of 3 independent plasma concentration time courses. Plasma samples and controls (25 μL) are extracted with 4 volumes of acetonitrile containing an internal standard and analyzed by liquid chromatography tandem mass spectrometry.

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

• [1]. Zarrinkar PP, et al. AC220 is a uniquely potent and selective inhibitor of FLT3 for the treatment of acute myeloid leukemia (AML). Blood, 2009, 114(14), 2984-2992.  [Content Brief]

  [2]. Puissant A, et al. SYK is a critical regulator of FLT3 in acute myeloid leukemia. Cancer Cell. 2014 Feb 10;25(2):226-42.  [Content Brief]

  [3]. Sun X, et al. PROTACs: great opportunities for academia and industry. Signal Transduct Target Ther. 2019 Dec 24;4:64.  [Content Brief]