Effects of Janus Kinase Inhibitor tofacitinib on circulating serum amyloid A and interlukin-6 during treatment for rheumatoid arthritis
Tofacitinib is a JAK inhibitor currently approved for the treatment of RA in some parts of the world. In this paper, Migita et al tested the effects of tofacitinib on circulating serum amyloid A (SAA). SAA is a major acute-phase reactant in RA and studies have shown it may be a better marker for the assessment of inflammatory joint disease compared with C-reactive protein. SAA is induced by the binding of IL-6 and the activation of the JAK/STAT pathway, which is inhibited by tofacitinib. Results from the study show that SAA levels fell between treatment initiation and week 4. It was noted that the reduction in levels was greater in the tofacitinib + MTX group when compared with tofacitinib monotherapy. This ability to regulate serum levels of SAA, as well as appearing to have a down regulatory effect on serum levels of IL-6, could give a mechanistic basis to support tofacitinib’s anti-inflammatory properties.