Preventive treatment for neuromyelitis optica spectrum disorder in Japan

Abstract

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory disease of the central nervous system involving aquaporin–4 antibodies, and complement is strongly implicated in its pathogenesis. In other words, the presence of aquaporin–4 antibodies, disruption of the blood–brain barrier, and complement activation are all necessary for the development of NMOSD. Pathologically, the focus of inflammation is around blood vessels, and in addition to lymphocyte and macrophage infiltration, there is a common finding of complement and IgG deposition and loss of staining for aquaporin 4 and GFAP. As in other autoimmune diseases, B–cell depletion therapy and IL–6 receptor antibodies are effective in preventing relapses, and complement C5 inhibitors can almost completely suppress clinically severe relapses. In the past, oral glucocorticoids (GCs) were prescribed in almost all cases and unapproved oral immunosuppressants were used as adjuncts or substitutes, but the effect on relapse prevention was not sufficient and there were often problems with the side effects of GCs. With the approval of five expensive biologic agents, it is important to consider how to use them differently.