A comparative study of tolerability and effects on immunoglobulin levels and CD19 cell counts with ocrelizumab vs low dose of rituximab in multiple sclerosis

Background Rituximab (RTX) and ocrelizumab (OCR) are two anti-CD20 biologics used in MS; however, comparisons on safety and efficacy are rare. Objective To compare treatment outcomes over the first year with RTX and OCR. Methods Retrospective cohort study comprising MS patients initiating RTX at the Karolinska University Hospital (Sweden; n=311) and OCR at Rocky Mountain MS Clinic (Utah, USA; n=161), respectively. Results Levels of immunoglobulin G measured in blood dropped 0.16g/L (95% confidence interval 0.01 to 0.31) with each OCR infusion, but remained stable with RTX. In contrast, levels of immunoglobulin M decreased to a similar extent with both drugs. Ten and 15% of patients discontinued treatment with RTX and OCR, respectively (n.s), however, adverse events leading to treatment discontinuation were more common with OCR (6.8% vs 2.6%; p=0.026). Only 3.1 and 1.6% discontinued OCR and RTX, respectively, due to lack of effect (n.s). The degree of B cell depletion was superior with OCR. Conclusion Overall, differences between the two treatments were small. Although the study design precludes robust conclusions regarding the risk-benefit with the studied therapies, our findings indicate that the tolerability and safety with RTX is not inferior to OCR.