Anti-rheumatic effect of JAK-inhibitors

Treatment of rheumatoid arthritis (RA) has dramatically developed with the use of biologics targeting inflammatory cytokines. However, expense and parenteral use can cause issues in the initiation and continuation of the treatment. Therefore a new orally available anti-rheumatic drug has been long-awaited. Recently, small-molecule compounds targeting Janus kinase (JAK) has shown clinical efficacy similar to biologics in clinical trials for active RA. Among the JAK-inhibitors, new drug application for tofacitinib is concurrently under review in western and asian countries and is highly expected to become a new anti-rheumatic drug in the near future. In order to evaluate the mode of action, we utilized peripheral blood and synovium from RA patients. Proliferation and cytokine production of CD4+ T cell was prominently reduced and subsequently inhibited cartilage destruction by the synovium. Our result is in line with the inhibitory effect of tofacitinib on joint destruction in RA patients those who were treated with tofacitinib. Therefore, further clinical efficacy is expected in the in the long-term treatment with tofacitinib.