In vitro activity: GSK1838705A potently and ATP-competitively inhibits IGF-1R and IR with appKi values of 0.7 nM and 1.1 nM, respectively.In cells, GSK1838705A potently inhibits ligand-induced phosphorylation of IGF-1R and IR with IC50 of 85 nM and 79 nM, respectively. GSK1838705A shows the significant anti-proliferative effect in a panel of cell lines derived from solid and hematologic tumors such as L-82, SUP-M2, SK-ES and MCF-7 cells with EC50 of 24 nM, 28 nM, 141 nM and 203 nM, respectively. GSK1838705A shows an accumulation of MCF-7 and NCl-H929 cells predominantly in G1 (2N) phase of the cell cycle. GSK1838705A also inhibits ALK with Ki of 0.35 nM and supresses the proliferation of nucleophosmin (NPM)-ALK fusion cells with EC50 of 24-88 nM. GSK1838705A potently inhibits NPM-ALK phosphorylation in Karpas-299 and SR-786 cells, while has modest effect on STAT3 phosphorylation.

Kinase Assay: Baculovirus-expressed glutathione S-transferase-tagged proteins encoding the intracellular domain of IGF-1R (amino acids 957-1367) and IR (amino acids 979-1382) are used for determinations of IC50s by a homogeneous time-resolved fluorescence assay. A filter binding assay is used for appKi determinations using activated IGF-1R and IR kinases. Expanded kinase-selectivity profiling of GSK1838705A is carried out by screening the compound in the KinaseProfiler panel.

Cell Assay:Cells ( L-82, SUP-M2, SK-ES and MCF-7) are seeded in 96-well dishes, incubated overnight at 37 °C, and treated with DMSO or GSK1838705A for 72 hours. For the NIH-3T3/LISN proliferation assays, cells are seeded on collagen-coated 96-well tissue culture plates and allowed to adhere for 24 hours. The medium is replaced with serum-free medium and the cells are treated with GSK1838705A for 2 hour. Cells are incubated for 72 hours after addition of IGF-I (30 ng/mL). Cell proliferation is quantified using the CellTiter-Glo Luminescent Cell Viability Assay.

Mol Cancer Ther. 2009 Oct;8(10):2811-20.