In vitro activity: TAE684 does not exhibit significant cross-reactivity against other kinases. TAE684 potently inhibits the proliferation of Ba/F3 NPM-ALK cells with IC50 of 3 nM, without affecting the survival of Ba/F3 cells even at 1 μM. TAE684 also inhibits proliferation of NPM-ALK-expressing human ALCL cell lines including Karpas-299 and SU-DHL-1 with IC50 of 2–5 nM. Molecular modeling reveals that L258 may be one of the major kinase-selectivity determinants for TAE684. TAE684 treatment results in a rapid and sustained inhibition of phosphorylation of NPM-ALK. TAE684 induces apoptosis and G1 phase arrest in NPM-ALK-expressing Ba/F3 cells and ALCL patient cell lines. TAE684 markedly overcomes Crizotinib-resistance in H3122 CR cells, harboring the fusion oncogene EML4-ALK, decreasing cell growth, suppressing ALK phosphorylation and inducing apoptosis. Neurite outgrowth induced by expression of the mALK R1279Q mutant could be completely inhibited by TAE684 at 30 nM.

Kinase Assay: All in vitro enzyme assays are done at Upstate Biotechnology with the exception of InsR and IGF-1R. To determine the IC50 of TAE684 against InsR and IGF-1R a homogeneous time-resolved fluorescence assay is performed. ATP (10 mM) and 20 mg/ml biotinylated PolyEY (Glu, Tyr 4:1) are combined with 50 nL of serial dilutions of TAE684 (10-500 nM) and 4 ng of InsR enzyme in the presence of the kinase reaction buffer (20 mM TrisCl, pH 7.5/10 mM MgCl2/3 mM MnCl2/1 mM DTT/10 mM NaVO4/0.1 mg/ml of BSA). Assays are incubated for 1 hour at ambient temperature. Reactions are terminated by adding 10 mL of the detection solution containing 50 mM EDTA, 500 mM KF, 0.5 mg/ml of BSA, 5 mg/mL Eu3+ cryptate-labeled anti-phosphotyrosine antibody Mab PT66-K, and 5 mg/mL Streptavidin-XLent. The reaction is incubated for half an hour, and fluorescence signals are read on Analyst GT.

Cell Assay: Cells (Luciferase-expressing Karpas-299, SU-DHL-1, and Ba/F3 cells and transformed Ba/F3 stably expressing NPM-ALK, Bcr-Abl, or TEL-kinase fusion constructs) are seeded in 384-well plates (2.5×104 cells per well) and incubated with serial dilutions of TAE684 or DMSO for 2–3 days. Luciferase expression is used as a measure of cell proliferation/survival and is evaluated with the Bright-Glo Luciferase Assay System. IC50 values are generated by using XLFit software.

Proc Natl Acad Sci U S A. 2007 Jan 2;104(1):270-5; Proc Natl Acad Sci U S A. 2011 May 3;108(18):7535-40; Biochem J. 2011 Dec 15;440(3):405-13.