Tofacitinib (INN) is a drug of the janus kinase (JAK) inhibitor class, discovered and developed by the National Institutes of Health and Pfizer. Tofacitinib is marketed as Xeljanz and Jakvinus.It is currently approved for the treatment of rheumatoid arthritis (RA) in the United States and other countries.It has demonstrated effectiveness in the treatment of psoriasis in Phase 3 studies. It is being studied for treatment of inflammatory bowel disease, and other immunological diseases, as well as for the prevention of organ transplant rejection.
It is an inhibitor of the enzyme janus kinase 1 (JAK1) and janus kinase 3 (JAK 3) , which means that it interferes with the JAK-STAT signaling pathway, which transmits extracellular information into the cell nucleus, influencingDNA transcription.In a mouse model of established arthritis, tofacitinib rapidly improved disease by inhibiting the production of inflammatory mediators and suppressing STAT1-dependent genes in joint tissue. This efficacy in this disease model correlated with the inhibition of both JAK1 and 3 signaling pathways, suggesting that tofacitinib may exert therapeutic benefit via pathways that are not exclusive to inhibition of JAK3.
