Progress in the Treatment of Neuromyelitis Optica Spectrum Disorder: From Pathogenic Insights to Biologics.

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory disease of the central nervous system that affects the optic nerve and spinal cord. Attacks often result in severe neurological disabilities, which make relapse prevention critical. Conventional therapies rely on glucocorticoids (GCs) and immunosuppressants; however, relapses may still occur and long-term administration can cause adverse effects. Following the discovery of anti-aquaporin-4 (AQP4) antibodies, NMOSD has been recognized as an independent "astrocytopathy" distinct from multiple sclerosis, and the development of molecular targeted therapies has advanced rapidly. Recently, biologics such as complement inhibitors (eculizumab and ravulizumab), IL-6 receptor inhibitors (satralizumab), and B-cell-depleting agents (inebilizumab and rituximab) have been successively introduced. These biologics demonstrate better relapse prevention than conventional treatments and also contribute to the tapering of GC. Drugs have different mechanisms of action, administration, and side effect profiles; therefore, treatment selection should be individualized. This review summarizes the recent progress in this field.