Upadacitinib is a JAK1 inhibitor (IC50 = 47 nM). It is selective for JAK1 over JAK3 and tyrosine kinase 2 (Tyk2; IC50s = 2,304 and 4,690 nM, respectively), as well as a panel of 83 additional kinases at 1 μM, but does inhibit JAK2, Rho-associated kinase I (ROCK1), and ROCK2 (IC50s = 120, 920, and 430 nM, respectively). Upadacitinib decreases cytokine-induced STAT phosphorylation in a variety of human cells with IC50 values ranging from 1.6 to 649 nM. It reduces M. tuberculosis-induced paw swelling and bone erosion in a rat model of arthritis when administered at doses of 1, 3, and 10 mg/kg twice per day for 17 days. Formulations containing upadacitinib have been used in the treatment of rheumatoid arthritis.
