LAUSR

ABSTRACT Introduction Persistent and excess IL-6 production often contributes to a variety of immune diseases. IL-6–targeting therapy was first approved for Castleman disease, then rheumatoid arthritis, and now it is broadly used. Furthermore, it has been approved not only for chronic and acute inflammatory diseases but also for autoantibody-induced diseases such as neuromyelitis optica spectrum disorder and interstitial lung disease due to systemic sclerosis. Areas covered This review summarizes laboratory changes after IL-6 inhibition and molecular changes in the immune cell. A wide range of diseases is discussed, from those for which the efficacy of IL-6–targeting therapy is approved worldwide to those for which only a small number of clinical cases have been reported. It summarizes the characteristics of the diseases for which IL-6–targeting therapy is expected to be effective. Expert opinion Clinical evidence has demonstrated that IL-6–targeting therapy is relatively safe; however, it is necessary to be cognizant of early detection of infectious disease, as inhibition of IL-6 masks inflammation. Although many of the cases for which IL-6–targeting therapy was effective or partially effective still require validation through clinical trials, the therapy is suggested as a candidate treatment option for various refractory immune diseases.