Comparative effectiveness of rituximab versus ocrelizumab in relapsing multiple sclerosis on clinical relapses and radiological outcomes in British Columbia, Canada

Background: Recent research has suggested that rituximab is not non-inferior to ocrelizumab in the treatment of relapsing multiple sclerosis (RMS). We compared the effectiveness of rituximab versus ocrelizumab in RMS. Methods: Individuals with RMS treated with rituximab or ocrelizumab with ⩾12 months of clinical follow-up and/or post-rebaseline magnetic resonance imaging (MRI) data were propensity-scored matched 1:1 and included. Objectives: Primary outcomes were annualized relapse rate (ARR), ARR ratio and cumulative hazard of relapses. The secondary outcome was the proportion of each group demonstrating post-rebaseline radiological activity. Results: In total, 538 individuals were included in the primary (clinical) outcome analysis and 350 individuals were included in the secondary (radiologic) outcome analysis. Over a median 2-year follow-up, very low ARR was observed in both groups (rituximab: 0.05 (95% CI: 0.03–0.08) versus ocrelizumab: 0.03 (95% CI: 0.02–0.05)). The adjusted ARR ratio for rituximab compared with ocrelizumab was elevated at 1.76 (95% CI: 0.70–4.59), and the adjusted cumulative hazard of relapses was also elevated for rituximab-treated individuals (HR = 2.17 (95% CI: 0.91–5.1)). Conclusion: Although our results suggest that rituximab may be inferior to ocrelizumab for relapse suppression, the rarity of relapses underpowered comparisons, and no definitive conclusions could be drawn.