Recent changes in the frequency of use of apheresis and biological drugs in the treatment of neuromyelitis optica spectrum disorders.

Dear Editor, Neuromyelitis optica spectrum disorders (NMOSD) is an immunological neurological disease caused by antiaquqporin-4 (AQP4) antibodies which trigger severe damage to the optic nerve and spinal cord. Steroid pulses are used as treatment in the acute phase of the disease, but not a few cases are unsuccessful, for which apheresis is often later performed [1]. Steroids and immunosuppressive drugs are conventionally used to prevent NMOSD recurrence, but are sometimes inadequate. Biological drugs (biologics) that have emerged in recent years have been shown to be effective in refractory cases. In Japan, biologics were approved for the prevention of relapse starting in November 2019 for eculizumab, an anti-C5 antibody, followed by satralizumab, an anti-IL-6 receptor antibody in August 2020, inebilizumab, an antiCD-19 antibody in March 2021, and rituximab, an antiCD20 antibody in June 2022 [2]. Herein, we present how the clinical characteristics and treatment of NMOSD have changed with the advent of biologics, and discuss the role of apheresis in this treatment. We retrospectively examined patients with NMOSD, diagnosed using the 2015 diagnostic criteria [3], who attended our hospital. Clinical information was