In vitro activity: In Ba/F3 cells overexpressing the constitutively active Tel-TRKC fusion, GNF-5837 shows potent anti-Trk activity and potent antiproliferation activity with IC50 of 0.042 μM.

Kinase Assay: TrkA and TrkC biochemical assays are carried out by HTRF method. The reaction mixtures contains 1 μM peptide substrate, 1 μM ATP, and either 1.8 nM TrkA or 34 nM TrkC in the reaction buffer (50mM HEPES pH 7.1, 10mM MgCl2, 2 mM MnCl2, 0.01% BSA, 2.5 mM DTT and 0.1 mM Na3VO4) at a final volume of 10 μL. All reactions are carried out at room temperature in white ProxiPlate(TM) 384-well Plus plates and are quenched with 5 μL of 0.2mM EDTA at 60 min. Five μL of the detection reagents (2.5 ng PT66K and 0.05 μg SAXL per well) are added, the plates are incubated at room temperature for 1 h and then read in EnVision reader. Compounds are diluted into assay mixture (final DMSO 0.5%), and IC50 values are determined by 12-point (from 50 to 0.000282 μΜ) inhibition curves in duplicate under the assay conditions. TrkB biochemical assay is carried out by caliper microfluidic method. The reaction mixtures contained 1 μM peptide substrate, 10 μM ATP, and 2 nM TrkB in a reaction buffer containing 100 mM HEPES, pH 7.5, 5 mM MgCl2, 0.01% Triton X-100, 0.1% BSA, 1 mM DTT, 10 μΜNa3VO4, and 10 μΜBeta-Glycerophosphate. The reactions are carried out at room temperature for 3 hrs, and the products are determined by Caliper EZ-reader. Compounds are diluted into assay mixture (final DMSO 1%), and IC50 values are determined by 12-point (from 50 to 0.000282 μΜ) inhibition curves in duplicate under the assay conditions.

Cell Assay: Compounds are tested for their ability to inhibit the proliferation of wt Ba/F3 cells and Ba/F3 cells transformed with constitutively expressed luciferase reporter and BCR-ABL or Tel-KDR or other Tel fusion kinases. Parental Ba/F3 cells are maintained in media containing recombinant mouse IL3 and the kinase transformed Ba/F3 cells are maintained in media without IL-3. 7.5 nL of compounds are spotted to each well of 1536-well assay plates by Liquid handling System Echo 555 (Labcyte). 700 cells are then plated into each well of the assay plates in 7 μL culture media per well and compounds are tested at 0.17 nM to 10 uM in 3-fold serial dilutions. The cells were then incubated for 48 hours at 37 °C. 3 μL of Bright-Glo(R) is added to each well and the plates are read using ViewLux. Cell line: Wt Ba/F3 cells and Ba/F3 cells transformed with constitutively expressed luciferase reporter and BCR-ABL or Tel-KDR or other Tel fusion kinases

ACS Med Chem Lett. 2012 Jan 1;3(2):140-5.