2019 Volume 31 Issue 2 Pages 162-168
The treatment of rheumatoid arthritis（RA）has improved dramatically following the advent of biological disease-modifying antirheumatic drugs（bDMARDs）. However, these bDMARDs require intravenous or subcutaneous injection and some patients fail to respond to them. Janus kinase （JAK）, which constitutively binds to cytokine receptors, plays an important role in the pathological processes of RA. Several JAK inhibitors that belong to a class of targeted synthetic DMARDs have been developed as new therapies for patients with RA. Two JAK inhibitors, tofacitinib and baricitinib, have already been approved in Japan. Results of phase III clinical trials using those JAK inhibitors have shown feasible efficacy and tolerable safety. Both drugs are effective in patients who showed inadequate response to bDMARDs as well as conventional synthetic DMARDs such as methotrexate. Since serious infections occur at a rate similar to other bDMARDs, the patients should be monitored carefully and regularly for adverse effects. Although JAK inhibitors are potent therapies for RA, more cautious consideration and measurement for their risk-benefit ratio are needed, after considering the safety results of ongoing post marketing surveillance.
