JAK inhibitors in rheumatology.

Janus kinase inhibitors (JAKis) are a group of drugs with a different mechanism of action from biologics and are most rapidly uptaken in the rheumatology field. JAK is a protein kinase activated in the cytoplasm by multiple cytokines and hormones involved in inflammatory pathology. The expression of JAK has been observed in various diseases, indicating the utility of JAK inhibitors in a wide variety of immune-mediated inflammatory diseases. Clinical trials are underway for a number of different rheumatic diseases based on the therapeutic efficacy of JAKis, which is comparable to that of biologics. This article will review the current status of JAKis for rheumatic diseases in terms of efficacy and safety and extend to future clinical applications for rare diseases.