Long-term Safety of Rituximab in Primary Sjögren Syndrome: The Experience of a Single Center

Objective: This work aims to evaluate the long-term safety of rituximab (RTX) in primary Sjögren syndrome (pSS) and to determine the safety and the efficacy of long-term treatment with B cell depleting therapy in pSS patients with active systemic disease. Methods: A historical cohort study, enrolling 35 patients with pSS treated with RTX between 2008 and 2019 in a single rheumatologic unit, was performed. When patients experienced adverse events, the treatment was suspended and patients' data were recorded. Results: The included patients were mainly female (91%), with a mean age of 54 years. During the time of observation, 13 patients (37.1%) suspended RTX treatment (10 cases per 100 patient-years, 95% CI 0.06-0.17). Baseline demographics, disease characteristics, European Alliance of Associations for Rheumatology (EULAR) Sjögren's Syndrome Disease Activity Index (ESSDAI) values, and treatment were comparable across RTX-suspended and nonsuspended groups. Patients exposed to RTX had been followed for 35.82 ± 32.56 months, and the time of observation varied from 6 to 96 months. All the patients except one experienced a significant and persisting meaningful improvement of their ESSDAI (≥ 3 points) during the long-term follow-up. For the duration of the follow-up, 13 (37%) patients discontinued RTX treatment. Four out of 13 (30.8%) discontinued the treatment after the first administration due to infusion-related reactions. During subsequent RTX courses, the main cause of withdrawal was hypogammaglobulinemia onset (7 patients). In 2 patients, hypogammaglobulinemia was associated with severe infections. Conclusion: Long-term RTX administration was shown to be a safe, well tolerated, and effective treatment in patients with active systemic disease, significantly reducing ESSDAI and controlling disease activity. Keywords: hypogammaglobulinemia; primary Sjögren syndrome; rituximab; safety.