Background/Purpose: Rituximab targets CD20-bearing B cells and is used to treat Rheumatoid Arthritis (RA). Common Variable Immune Deficiency (CVID) is a primary immune deficiency syndrome with immune dysregulation, hypogammaglobulinemia, and recurrent infections. It was hypothesised that iatrogenic B cell depletion could produce a CVID-like phenotype. We sought to evaluate the safety of long-term Rituximab administration in RA patients.

Methods: A systematic review of the Medline/Embase, Web of Science, and Cochrane Library databases was conducted until February 2023. Observational studies in RA populations evaluating the safety of >2 courses of Rituximab, and/or >12 months’ exposure to Rituximab were included. Exclusion criteria were case series, short-term exposure to Rituximab, or studies with patients under 16 years of age. Data on adverse events (hypogammaglobulinemia, severe infections, serious adverse events) were extracted. Pooled incidence rates of adverse events were calculated by random-effects meta-analysis.

Results: Twenty-three studies were included, reporting 253 episodes of hypogammaglobulinemia, 964 severe infections, and 1,903 severe adverse events, from a total 19,855 patient-years (PY) exposure. Their pooled incidence rates/100PY were 1.57 [95% confidence interval (95%CI) 1.24-1.89], 3.22 (95%CI 2.95-3.48), and 8.07 (95%CI 7.60-8.54), respectively. Event rates did not increase with longer duration of exposure.

Conclusion: The safety risk of long-term exposure to Rituximab appears to be consistent over time. However, there was high heterogeneity in the outcomes, limited data on use beyond 5 years, and risk of bias was substantial. More research on long-term safety of Rituximab is required to address this.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/long-term-safety-of-rituximab-in-rheumatoid-arthritis-a-systematic-review-and-meta-analysis/