Abstract
Background Ocrelizumab, a humanised anti-CD20 monoclonal, is a highly effective treatment for relapsing-remitting multiple sclerosis (RRMS). Long-term safety of B-cell depletion in RRMS is uncertain and there is no data on dose reduction of ocrelizumab as a risk mitigation strategy. Experience with rituximab suggests dose reduction paradigms may maintain efficacy whilst reducing side effects.
Objectives To evaluate effectiveness and safety of reducing ocrelizumab dose from 600 to 300mg every 6 months in patients with RRMS.
Methods Data was collected through the Townsville neurology service. Following standard randomised controlled trial regimen of 600mg every 6 months for 2 years, patients consented to dose reduction to 300mg every 6 months. Patients were included if they were diagnosed with RRMS, and received at least one reduced dose of ocrelizumab. Relapse, disability progression, new magnetic resonance imaging (MRI) lesions, CD19+ cell count, and immunoglobulin concentrations were analysed.
Results 29 patients were included, a total of 150 full and 86 reduced doses, mean follow-up on reduced dose was 17 (1–28) months. We observed no relapse or new MRI activity in the cohort receiving the reduced dose. No new safety concerns arose. Data regarding disability, CD19+ cell counts and immunoglobulin concentrations will be reported.
Conclusions In this single-centre observational study, dose reduction of ocrelizumab from 600 to 300mg every 6 months after 2 years appeared to maintain efficacy in terms of new inflammatory disease activity. A randomised trial may be warranted to confirm this and explore the impact of dose reduction on long-term safety.
