Efficacy and safety of mitoxantrone in patients with highly relapsing neuromyelitis optica

Objective: To evaluate the efficacy and safety of mitoxantrone hydrochloride and determine how it exhibits a differential inhibitory effect on subsets of B cells in patients with highly relapsing neuromyelitis optica (NMO). Design: Retrospective case series with prospective follow-up. Setting: Three referral medical centers in the Republic of Korea. Patients: Twenty patients with highly relapsing NMO or neuromyelitis optica spectrum disorder who had at least 2 relapses during the year preceding the start of mitoxantrone treatment, despite other immunotherapies. Intervention: Infusions of mitoxantrone up to a maximum cumulative dose of 120 mg/m². Main Outcome Measures: Annualized relapse rate, disability according to the Expanded Disability Status Scale score, and fraction of CD27⁺CD19⁺ memory B cells. Results: During mitoxantrone treatment, the median annualized relapse rate was reduced by 75%, and 50% of patients became relapse free. Disability improved or stabilized in all patients. No patients had serious adverse effects during the mean follow-up period of 41 months after completing therapy. Flow cytometric analysis of cell surface markers revealed that mitoxantrone treatment preferentially affected CD27⁺CD19⁺ memory B cells. Conclusions: Treatment with mitoxantrone in patients with highly relapsing NMO significantly reduces relapse rates, resulting in subsequent functional stabilization or improvement.