Tofacitinib

Tofacitinib (CP-690550) is a potent, specific, orally active inhibitor of JAK3 with IC50 of 1 nM in cell-free assays; displays 20- to 100-fold less potency for JAK2 and JAK1 (IC50=20 nM and 112 nM, respectively), and shows no potent activity against 30 other kinases at >3 uM (CaMK1, ROCK2, Lck, MST2, etc.); effectively inhibits a murine mixed lymphocyte reaction (MLR) with IC50 of 91 nM, significantly prolonges survival in a murine model of heart transplantation and in cynomolgus monkeys receiving kidney transplants.Rheumatoid Arthritis Approved(In Vitro):Tofacitinib (CP-690550) citrate binds potentially at JAK3 and JAK2 as 2.2 nM and 5 nM (Kd). The report includes additional binding for Tofacitinib at Camk1 (Kd of 5,000 nM), DCamkL3 (Kd of 4.5 nM), Mst2 (Kd of 4,300 nM), Pkn1 (Kd of 200 nM), Rps6ka2 (Kin.Dom.2-C-terminal) (Kd of 1,400 nM), Rps6ka6 (Kin.Dom.2-C-terminal) (Kd of 1,200 nM), Snark (Kd of 420 nM), Tnk1 (Kd of 640 nM) and Tyk2 (Kd of 620 nM).\n(In Vivo):Animals that are treated with Tofacitinib show a significantly lower production of anti-drug antibodies (ADAs) compare with PEG-treated control mice (for five weeks after initial immunization, p4 hours.