Anti-CD20 monoclonal antibody (mAb) therapies have shown a marked reduction in multiple sclerosis (MS) inflammatory activity by selectively depleting B lymphocytes. Rituximab is a chimeric mAb whereas ocrelizumab is fully humanized. Clinical trial efficacy and safety data suggest a favorable benefit-to-risk profile. However, there is a paucity of literature on comparative real-world safety profile of rituximab and ocrelizumab.
To investigate the adverse events (AEs) associated with rituximab and ocrelizumab reported to the Food and Drug Administration adverse event (AE) Reporting System (FAERS) database.
The FAERS database query was filtered by reason for use (MS) and suspected active component (rituximab or ocrelizumab). In order to identify drug-AE associations, disproportionality analyses including but not limited to reporting odds ratio (ROR) were conducted. A signal was detected if the lower limit of the 95% two-sided confidence interval of ROR (ROR025) exceeded 1.
There were 623 and 7,948 reports for rituximab and ocrelizumab, respectively. The most frequently reported AEs with rituximab and ocrelizumab were infusion related reactions (4.82%) and urinary tract infections (10.52%), respectively. The strongest drug-AE association for rituximab and ocrelizumab were ear pruritus (ROR25 47.53) and oral herpes (ROR025 38.99), respectively. When classified by AE class, ocrelizumab was associated with a nearly two-times higher frequency of infections than rituximab (21.93% vs 11.05%, respectively).
This study revealed notable differences between rituximab and ocrelizumab. Specifically, infections were reported more frequently with ocrelizumab. A potentially more robust B cell depletion by ocrelizumab leading to more profound immunosuppression could explain these findings. Additional studies are needed to further investigate these differences.