Tofacitinib in the treatment of ankylosing spondylitis
Tofacitinib is a targeted synthetic disease-modifying antirheumatic drug that is approved for the treatment of rheumatoid arthritis and other rheumatic diseases. Tofacitinib selectively inhibits JAK/STAT signalling system and modulates cytokines, including interleukin (IL)-17, IL-21 and IL-23, that are essential for the pathogenesis of ankylosing spondylitis (AS). In phase III, 48-week, randomised, double-blind, placebo-controlled study that enrolled patients diagnosed with active AS, the ASAS20 response rate at 16 weeks (the primary end-point) was significantly greater with tofacitinib 5 mg twice daily versus placebo. These findings were supported by analysis of the ASAS40 response rate and other secondary efficacy endpoints, which demonstrated significant improvements with tofacitinib versus placebo in disease activity, mobility, function and health-related quality of life. The effect of tofacitinib was rapid (as early as week 2) and was sustained up to the end of the open-label phase (week 48). Based on the results of this study, tofacitinib was approved for treatment of active AS in adult patients with an inadequate response or intolerance to >2 non-steroidal anti-inflammatory drugs.