Tofacitinib (CP-690550) Citrat

Tofacitinib citrate inhibits IL-2-mediated human T cell blast proliferation and IL-15-induced CD69 expression with IC50 of 11 nM and 48 nM, respectively. Tofacitinib citrate prevents mixed lymphocyte reaction with IC50 of 87 nM. Tofacitinib citrate treatment of murine factor-dependent cell Patersen–erythropoietin receptor (FDCP-EpoR) cells harboring human wild-type or V617F JAK2 leads to prevention of cell proliferation with IC50 of 2.1 µM and 0.25 µM, respectively. Tofacitinib citrate inhibits interleukin-6-induced phosphorylation of STAT1 and STAT3 with IC50 of 23 nM and 77 nM, respectively. Moreover, Tofacitinib citrate generates a significant pro-apoptotic effect on murine FDCP-EpoR cells carrying JAK2V^V617F, whereas a lesser effect is observed for cells carrying wild-type JAK2. This activity is coupled with the inhibition of phosphorylation of the key JAK2^V617F-dependent downstream signaling effectors signal transducer and activator of transcription (STAT)3, STAT5, and v-akt murine thymoma viral oncogene homolog (AKT). ^[2] Additionally, Tofacitinib citrate prevents IL-15-induced CD69 expression in human and cynomolgus monkey NK and CD8+ T cells in vitro. ^[3]