Cp-690550 - JAK3 inhibitor immunosuppressant treatment of rheumatoid arthritis treatment of transplant rejection

Standard immunosuppressive agents used in the clinic for the prevention of organ transplant rejection and autoimmune diseases, although generally effective, target ubiquitously expressed molecules and are associated with significant adverse events. Identification of potential targets selectively expressed by immune cells has become a research priority in order to develop immunosuppressants devoid of the toxicities observed with current therapies. In this regard, targeting of Janus kinase 3 (JAK3) represents a potentially effective immunosuppressive strategy since expression of this signaling molecule is relatively restricted to immune cells and it is only used by cytokine receptors containing the gamma-chain (gamma c). CP-690550 is a novel JAK3 inhibitor that has exhibited potent immunosuppressive effects in preclinical transplantation and arthritis models and has been shown to be clinically safe and effective in preventing transplant rejection and improving symptoms of rheumatoid arthritis and psoriasis. CP-690550 continues to undergo phase II development as an immunosuppressive agent.