LY2784544(Gandotinib (LY2784544)) is a potent JAK2 inhibitor (IC50: 3 nM), effective in JAK2V617F(Ki: 0.245 nM). The selectivity is higher 8- and 20-fold than JAK1 and JAK3.

In severe combined immunodeficient mice, LY2784544 (administered orally) does not affect CD71/Ter119 positive erythroid progenitor cells within the spleen. LY2784544 significantly inhibits STAT5 phosphorylation in Ba/F3-JAK2 V617F-GFP xenografts (effective dose 50% [ED50]: 12.7 mg/kg). Additionally, in a JAK2 V617F-induced myeloproliferative neoplasm (MPN) model, LY2784544 (administered orally) reduces the tumor burden of Ba/F3-JAK2 V617F-GFP (ED50: 13.7 mg/kg).

In proliferation assays, LY2784544 exhibits an anti-proliferative effect on JAK2 V617F-driven cells, with an IC50 of 68 nM. It demonstrates a less potent effect on cells driven by wild-type JAK2 and JAK3, with IC50 values of 1356 nM and 940 nM, respectively. LY2784544 also inhibits IL-3-activated wild-type JAK2 with an IC50 of 2.26 μM.

LY2784544 is dissolved in DMSO and stored, and then diluted with appropriate medium before use[1]. Ba/F3 cells expressing JAK2V617F are placed in RPMI-1640-containing vehicle (DMSO) or LY2784544 (concentration range, 0.001-20 μM) (1×104 cells/96-well). Ba/F3 cells expressing wild-type JAK2 are treated similarly except IL-3 (2 ng/mL) is added. After a 72-hour incubation, cell proliferation is assessed by adding Cell Titer 96 Aqueous One Solution Reagent (20 μL/well). The IC50 for inhibition of cell proliferation is calculated using the GraphPad Prism 4 software[1].