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The Differential Impact of Ocrelizumab Versus Rituximab on Lymphocyte Count, Immunoglobulins, and Infection Rate
Ocrelizumab and rituximab are anti-CD20 monoclonal antibodies which have demonstrated efficacy in treating MS, NMOSD, and other related neurological conditions. While effective, safety concerns of these treatments, namely excessive immunosuppression, remains a concern. Limited data exist exploring differences in the safety profile between these two agents.
Objectives:
To evaluate differences in immunosuppressive safety profile between the anti-CD20 agents ocrelizumab and rituximab.
Methods:
An observational, cohort study was completed among patients of the University Hospitals Neurological Institute receiving ocrelizumab or rituximab for the treatment of MS, NMOSD, or other related neurological disorders from January 2018- January 2022. An exploratory analysis was performed investigating the differences in lymphocyte count, immunoglobulins, B-cell concentrations, and infection rates between the two therapies.
Results:
A total of 184 patients were included in the analysis. Thirty two patients received rituximab and 152 patients received ocrelizumab. Mean age (48.3 ±13.6 years) and gender (67% female) were similar between groups. Ocrelizumab was used exclusively for treating multiple sclerosis (92 patients RRMS, 43 PPMS, 17 SPMS) while rituximab was used to treat primarily NMOSD (19 patients), recurrent optic neuritis (4), neurosarcoidosis (3), RRMS (2), recurrent transverse myelitis (2), pachymeningitis (1), and recurrent autoimmune encephalitis (1). Total duration of therapy was longer among patients receiving rituximab (t=3.17, p-0.0018). Patients receiving rituximab were more likely to experience hypogammaglobulinemia during treatment, even after adjusting for therapy duration (25.0% vs. 9.20%; p=0.0212). No differences were observed between groups in on-treatment B cell concentration (p=0.3603), lymphocyte count (p=0.1667), or incidence of severe infections (p=0.4097).
Conclusions:
Patients receiving rituximab were more likely to have experienced hypogammaglobulinemia during treatment than those receiving ocrelizumab. However, the infection risk was similar in the two groups. Likewise, on-treatment lymphocyte count and B cell concentrations were similar between agents.