S-Ruxolitinib is the chirality of INCB018424, is a potent and selective small-molecule Janus kinase 1 (JAK1) and JAK2 inhibitor. It was initially developed to target the constitutive activation of the JAK-STAT pathway. Janus kinases (JAKs) are a family of cytoplasmic tyrosine kinases that mediates signals from the receptors for various cytokines and growth factors that have a key role in haematopoiesis and immune function. Ruxolitinib maintains its anti-JAK activity by competitive inhibition of the ATP-binding catalytic site of the kinase domain. Ruxolitinib is well absorbed at >95%. Exposure of JAK2V617F-positive Ba/F3 cells to ruxolitinib iss shown to result in reduced cellular proliferation.

Reference

[1].Ruben A. Mesa, Uma Yasothan, Peter Kirkpatrick. Ruxolitinib. Nature Reviews Drug Discovery. 2012; 11: 103-104
[2].John Mascarenhas, Ronald Hoffman. Ruxolitinib: The First FDA Approved Therapy for the Treatment of Myelofibrosis. Clinical Cancer Research. 2012; 18(11): 3008 - 3014