Objective To evaluate the efficacy and safety of repeated rituximab treatment based on the assessment of peripheral circulating memory B cells over 24 months in patients with relapsing neuromyelitis optica (NMO).
Design Prospective open-label study.
Setting Institutional referral center for multiple sclerosis.
Patients Thirty patients with relapsing NMO or NMO spectrum disorder.
Intervention Treatment protocol of rituximab consisted of an induction therapy (375 mg/m2 once weekly for 4 weeks or 1000 mg infused twice, with a 2-week interval between the infusions) followed by maintenance therapy. The maintenance therapy was repeated treatment with rituximab (375 mg/m2, once) whenever the frequency of reemerging CD27+ memory B cells was more than 0.05% in peripheral blood mononuclear cells by flow cytometric analysis.
Main Outcome Measures Annualized relapse rate, disability (Expanded Disability Status Scale score), anti–aquaporin 4 antibody level, and safety of rituximab treatment.
Results Of 30 patients, 28 showed a marked reduction in relapse rate while taking rituximab over 24 months. The relapse rate was reduced significantly, by 88%, and 70% of patients became relapse-free over 24 months. Disability either improved or stabilized in 97% of patients. Anti–aquaporin 4 antibody levels declined significantly following treatment with rituximab, consistent with the clinical response and the effect on CD27+ memory B cells. Repeated treatment with rituximab was generally well tolerated, and no clinically relevant adverse event leading to discontinuation of treatment was observed.
Conclusion Repeated treatment with rituximab appeared to produce consistent and sustained efficacy over 24 months with good tolerability in patients with NMO.