2023 Volume 40 Issue 3 Pages 279-282
Neuromyelitis optica spectrum disorder (NMOSD) is caused by aquaporin 4 (AQP4) antibodies and results in refractory inflammatory lesions in the central nervous system. Traditionally, oral prednisolone and immunosuppressive drugs have been used to prevent relapses, but in the past three years, four monoclonal antibody drugs, eculizumab, satralizumab, inebilizumab, and rituximab, have been approved in Japan. Among these, eculizumab, which targets complement C5, is highly effective in preventing relapse, even with monotherapy, immediately after induction. Even when used in patients who relapse despite receiving at least 10 mg/day of prednisolone, the dose of prednisolone can be reduced or discontinued relatively quickly. Because it blocks the terminal complement activation pathway, it can affect encapsulated bacterial infections, particularly Neisseria meningitidis infections, and therefore vaccination should be given before eculizumab administration, with a booster vaccination at least 8 weeks apart and a routine vaccination every 5 years. In addition, genetic analysis prior to administration is strongly recommended because the C5 polymorphism, present in 3.5% of Japanese patients, prevents eculizumab from binding to the drug and thus prevents it from being effective. Eculizumab has a 2–week dosing interval and is also available as an intravenous infusion, requiring a clinic visit every 2 weeks. However, ravulizumab, which targets the same C5, is expected to be approved soon because the administration interval can be extended to 8 weeks and the infusion time can be reduced by increasing the concentration.
