In vitro activity: WP1066 markedly inhibits the growth of HEL cells carrying the JAK2 V617F mutant isoform in a dose-dependent manner with IC20, IC50 and IC80 of 0.8, 2.3 and 3.8 μM. WP1066 at concentrations of 0.5, 1.0, 2.0, 3.0, or 4.0 μM inhibits the phosphorylation of JAK2, STAT3, STAT5, and ERK1/2 without affecting the phosphorylation of JAK1 and JAK3 in erythroid leukemia HEL cells that express the JAK2 V617F isoform. WP1066 at concentrations ranging from 0.5 to 3.0 μM inhibits the proliferation of AML colony-forming cells obtained from patients and that of the AML cell lines OCIM2 and K562 in a dose-dependent manner. WP1066 at concentrations of 0.5, 1.0, 2.0, 3.0, or 4.0 μM dose-dependently decreases JAK2 and pJAK2 protein levels as well as downstream phosphorylation levels of STAT3, STAT5, and AKT in OCIM2 and K562 cells. WP1066 at concentrations of 2 μM inhibits OCIM2 cell multiplication by inducing accumulation of cells at the G0-G1 phase of the cell cycle. WP1066 at concentrations of 1, 2, or 3 μM induces apoptosis in both OCIM2 and K562 cells in a dose-dependent fashion by activating procaspase-3 and cleaving PARP. WP1066 at concentrations of 5 μM prevents the phosphorylation of STAT3, and at concentrations of 2.5μM WP1066 significantly inhibits cell survival and proliferation in Caki-1 and 786-O renal cancer cells. WP1066 at concentrations of 5 μM suppresses HIF1α and HIF2α expression and VEGF production in Caki-1 and 786-O renal cancer cells.

Kinase Assay: WP1066 is an inhibitor of JAK2 and STAT3, and also shows effect on STAT5 and ERK1/2, without affecting JAK1 and JAK3.

Cell Assay: The 3, [4,5-dimethylthiazol-2-yl]-5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]-2H-tetrazolium (MTT) assay is done using an MTT-based cell proliferation/cytotoxicity assay system. Briefly, fresh low-density peripheral blood cells and various cell lines at the logarithmic phase of their growth are washed twice in RPMI 1640 containing 10% FCS and counted in a hemocytometer. Cell viability is assessed by the trypan blue (0.1%) staining method. Equal numbers of viable cells (5 × 104 per well) are incubated in a total volume of 100 μL of RPMI 1640 supplemented with 10% FCS alone or with WP1066 at increasing concentrations; the incubations are continued for up to 72 h in 96-well flat-bottomed plates at 37 °C in a humidified 5% CO2 atmosphere. Experiments for each condition are done in triplicate. After incubation, 20 μL of CellTiter96 One Solution Reagent are added to each well. The plates are then incubated for an additional 60 min at 37 °C in a humidified 5% CO2 atmosphere. Immediately after incubation, absorbance is read using a 96-well plate reader at a wavelength of 490 nm.