A Janus kinase 3–JAK3 inhibitor that interferes with the JAK-STAT signaling pathway which transmits extracellular information into the nucleus, downregulating transcription of inflammatory mediators and suppressing STAT1-dependent genes in joints. It is in clinical trials for managing psoriasis, inflammatory bowel disease, other immune disorders, and for preventing transplant rejection.
It was approved by the FDA in 2012 for managing moderately to severely active rheumatoid arthritis in adults who have not responded adequately to, or are intolerant of, methotrexate. Not surprisingly, it’s “pricey”–$2100/month.
Adverse effects Increased risk of opportunistic infections, tuberculosis, cancer and lymphoma.
Synonyms CP-690550, tasocitinib, Xeljanz