Background/Purpose: Rituximab (RTX), an anti-CD20 monoclonal antibody inducing B cell depletion, is used as therapy for diverse systemic autoimmune diseases (SAIDs), but is associated with adverse events (AE) such as infusion reactions, infections and others, which may lead to therapy suspension. We aim to evaluate the safety profile and persistence of RTX in SAIDs and factors that influence on the development of infections in real-life practice.

Methods: A retrospective observational study was conducted including patients diagnosed of SAIDs treated in a tertiary hospital between 2007 and 2018, who received at least 1 RTX infusion. At RTX initiation we collected clinical and demographic data including: age, sex, Charlson score, comorbidities, previous use of immunosuppressants (IM), biologic therapy and/or JAK inhibitors, use/dose of concomitant glucocorticoids (GC) and/or immunosuppressants and RTX dose. During treatment we analyzed: serum immunoglobulin (Ig) levels, number of RTX cycles and adverse events.

Results: 60 patients were included (73.3% women, mean age 52.8 ± 14.9 years), with median Charlson score of 3 (P25–75 1-4) and median disease evolution of 7.5 years (P25–75 1.2-12.6). Table 1 shows distribution of  SAIDs.

Prior to RTX 85% of patients received IM, 48.3% biologic agents (16.7% >1) and 5% JAK inhibitors. Associated to RTX 58.3% of patients received IM and 81.7% GC (median dose 12.5mg, P25–75 7.5-15). Total RTX cycles registered were 215.5 with a median of 2.25 (P25–75 1.3-5) cycles per patient. 
In terms of AE: 18 patients presented infusion reaction (72.2% were mild, 61.1% related to first cycle and 27.8% had recurrent infusion reactions). 28 patients presented infections (75% had >1), total number of infections was 64 (35 respiratory, 11 urinary, 6 skin and soft tissue, 4 gastrointestinal, 3 non-diseminated herpes zoster, 2 septic shock, 1 Pneumocystis Jiroveci pneumonia, 1 head and neck and 1 gynecological), 10 of them were serious and 1 was an opportunistic infection. There were 4 neoplasia (2 non-melanoma skin cancer, 1 bladder carcinoma and 1 ampullary carcinoma). 2 patients presented neutropenia and 1 presented an intersticial pneumonitis.
During RTX treatment 35% of patients had low Ig G and 48.3% low Ig M levels. None developed low Ig A levels. RTX was suspended in 26 patients (10 AE and 16 other reasons). 5 deaths were reported (2 infections, 2 unknown and 1 pulmonary fibrosis progression).
Low Ig G levels during RTX treatment were associated with the presence of infection (p< 0.042). Patients who had infection received more RTX cycles and higher doses of GC than those who did not, but there wasn’t association on statistical analysis. 
Kaplan Meier analysis showed less probability of continuing RTX therapy among SSc patients (p< 0.0095).

Conclusion: RTX therapy was safe and the presence of serious AE infrequent. Low Ig G levels were associated with the presence of infection. SSc patients showed less probability of continuing RTX than the rest of SAIDs.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/rituximab-safety-and-persistence-in-patients-with-systemic-autoimmune-diseases/