AB0479 RITUXIMAB MAY BE BENEFICIAL IN THE TREATMENT OF SEVERE FORMS OF SYSTEMIC AUTOIMMUNE DISEASES REFRACTORY TO STANDARD IMMUNOSUPPRESSIVE THERAPY. NINE-YEARS EXPERIENCE FROM SINGLE CLINICAL CENTRE

Background: Rituximab (RTX) is anti-CD20 monoclonal antibody, registered for the treatment of rheumatoid arthritis (RA). It has been used in clinical practice “of label” in various other conditions including systemic autoimmune diseases – systemic lupus erythematosus (SLE), systemic scleroderma (SScl), Sjogren’s syndrome (SjS), polymyositis (PM) and dermatomyositis (DM) and ANCA associated vasculitides, but the results of clinical studies are inconherent. Nevertheless, RTX is frequently used in patients with severe forms of systemic autoimmune diseases with organ involvement after failure of conventional immunosupressive treatment. In Czech Republic, RTX may be used “of label” upon a special request in these special cases. Objectives: To evaluate indications, clinical characteristics, general efficacy, safety and the impact of RTX therapy in patients with systemic autoimmune diseases treated in the Institute of Rheumatology, Prague since 2009 (a retrospective study). Methods: The medical reports of all patients treated with RTX for other diagnosis than RA were analyzed and the clinical data (diagnosis, previous treatment with glucocorticosteroids and immunosuppressive drugs, number of RTX infusion, side effects and global evaluation of the efficacy by physician) were collected and analyzed. Results: In the years 2009 – 2018, 50 patients with various systemic autoimmune diseases were treated with RTX in our clinic (SLE: n=8, SjS: n=2, SScl: n=16, PM: n=6, DM: n=3, MCTD: = 1, ANCA associated vasculitides: n=11, overlap syndromes: n=3). Mean age of the group was 48,12 ±12,9 years at the first RTX treatment and all of the patients experienced previous failure of treatment with 1-6 immunosuppressants. The total number of RTX infusions was 208 with mean 5,32 applications per patient. We have followed the patients for 37,1 months (mean), ranging from 2-114 months. During the follow-up two patients died due to complications of the disease, two patients were lost from the follow-up. The treatment was effective in majority of patients (n=27) and global efficacy was evaluated as “excellent” in 2, “very good” in 10 and “good” in 15 patients. In seven patients the treatment had no effect and in 4 patients the effect could not be evaluated due to short time follow-up. The treatment was well tolerated by patients and we have experienced 39 moderate or severe infections (requiring antibiotics or hospitalization) mostly in patients with ANCA associated vasculitides. In several patients, mild decrease of IgG levels following the RTX treatment was observed but only in one patient required a subsequent substitution with immunoglobulines. We have not observed any malignancy in the group. The detailed characteristics and results of the patients by diagnosis are provided. Conclusion: Rixuximab may be beneficial in some patients with severe forms of systemic autoimmune diseases refractory to the standard immunosuppressive therapy. The treatment is generally well tolerated and the infections are the most common side effect. Acknowledgement: This study was supported by the Research Project No. 0002372801 of the Czech Ministry of Health. Disclosure of Interests: None declared