About JAK inhibitors

Abstract

Cytokines are central to the pathogenesis of rheumatoid arthritis（RA）. In addition to existing anti-rheumatic drugs, the use of biologics that target cytokines and other factors has made RA a disease in which remission can be achieved. Janus kinase（JAK）inhibitors have become an option for the treatment of RA and are expected to be effective in RA refractory to pre-existing treatment tools. In addition, the indications for the use of JAK inhibitors have been expanded to include diseases and conditions other than RA, such as inflammatory bowel disease and pneumonia due to the novel coronavirus disease（COVID-19）, and clinical trials are underway for systemic lupus erythematosus, psoriatic arthritis, and ankylosing spondylitis. The incidence of herpes zoster（HZ）with JAK inhibitors is elevated, especially in Japanese population, so it is important to accumulate clinical data. The recombinant herpes zoster vaccine may reduce the risk of HZ, but there are numbers of questions regarding its appropriate use. Recent trial with a JAK inhibitor has pointed out the possibility of an increased risk of malignancy, major cardiovascular events, and venous thromboembolism. The most immediate issue seems to be the vaccination against COVID-19 under the use of JAK inhibitors, for which recommendations have been made, but no policy has been established. In this paper, we will present the latest information on these issues and discuss measures to resolve them.