Ruxolitinib phosphate (INCB018424)(INCB018424 phosphate) is the first potent, selective, JAK1/2 inhibitor to enter the clinic with IC50 of 3.3 nM/2.8 nM, >130-fold selectivity for JAK1/2 versus JAK3.

JAK2:2.8 nM, JAK1:3.3 nM

Ruxolitinib (INCB018424) effectively and selectively attenuates signaling and proliferation mediated by JAK2V617F. It demonstrates potent inhibition of HEL cell growth, with an EC50 of 186 nM, and significantly elevates apoptosis levels in the Ba/F3-EpoR-JAK2V617F cell system. Additionally, Ruxolitinib suppresses the proliferation of hematopoietic progenitor cells in samples from primary MPN patients[1].

Ruxolitinib (180 mg/kg, p.o.) reduces the tumor burden of mice inoculated with JAK2V617F-expressing cells while not causing anemia or lymphopenia[1].

Ruxolitinib phosphate is dissolved in 0.2% DMSO. Cells are seeded at 2000/well of white bottom 96-well plates, treated with compounds from DMSO stocks (0.2% final DMSO concentration), and incubated for 48 hours at 37°C with 5% CO2. Viability is measured by cellular ATP determination using the Cell-Titer Glo luciferase reagent or viable cell counting. Values are transformed to percent inhibition relative to vehicle control, and IC50?curves are fitted according to nonlinear regression analysis of the data using PRISM GraphPad.