Background/Purpose: Rituximab (RTX) is a biologic therapy approved for the treatment of active rheumatoid arthritis (RA) refractory to tumour necrosis factor antagonists. It causes B cell depletion, with a progressive reduction of the levels of immunoglobulin (Ig) that may be associated with an increased risk of infection. Our objective was to analyse the long-term safety of treatment with RTX in patients with RA and other inflammatory arthritis, and especially the risk of severe infections.

Methods: We made a retrospective descriptive study including patients treated by the Rheumatology Department of a tertiary hospital from June 2006 to December 2013 who had received at least one cycle of treatment with RTX. We analysed: demographic data (age, sex), diagnosis and disease duration, positive rheumatoid factor (RF) or anti-cyclic citrullinated peptide antibodies (anti-CCP); previous biologic treatment; concomitant treatment: disease-modifying antirheumatic drugs (DMARD) and/or concomitant glucocorticoids (GC); number of cycles received; levels of immunoglobulin (Ig) and adverse effects, especially severe infections.

Results: 53 patients were included (85 % female, mean age 58.9 ± 12.9) until December 2013, who received a total of 169 cycles of RTX (mean: 3.3 ± 2.2 cycles/patient) during 7 years. Diagnoses were: RA (75.5 %), overlap syndrome (11.3 %), systemic lupus erythematosus (5.7 %), psoriatic arthritis (3.7 %), seronegative oligoarthritis (1.9 %) and juvenile idiopathic arthritis (1.9 %). Mean disease duration was 15.1 ± 8.4 years, 79.2 % were RF/anti-CCP positive, 67.9 % had received prior biological treatment, 37.7 % had received ≥ 2 or more biologic drugs, 77.3% received concomitant DMARDs (47.2% methotrexate, 30.2 % leflunomide, 11.3% hydroxychloroquine and 3.8 % mycophenolate mofetil) and 79.2% received GC. A progressive, significant decrease in IgG levels (p = 0.018), IgM (p = 0.018) and IgA (0.05), already evident after the first RTX cycle, was observed, although only 13.2% of patients had Ig levels below the normal range. Twenty-five adverse events were reported, of which 19 were considered drug-related: 2 infusion reactions, 2 cases of leukopenia and 15 infections (7 respiratory tract, 5 urinary tract, 1 soft tissue infection, 1 case of bacteremia and 1 septic shock), and 4 of which were considered serious according to medical criteria, although no patient discontinued RTX for those reasons. No opportunistic infection or malignancy was reported. Patients with low Ig levels did not have a greater number of infections than those with normal Ig levels.

Conclusion: After prolonged exposure to RTX, serious adverse events, including infections, were stable over time and multiple treatment courses, and showed a good safety profile, even in patients with reduced Ig levels.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/safety-of-rituximab-in-patients-with-chronic-inflammatory-arthritis-seven-year-follow-up-observational-study/