SAT0494 RITUXIMAB IN REFRACTORY PEDIATRIC RHEUMATIC DISEASES: FOCUS FOR THE SAFETY IN REAL CLINICAL PRACTICE
Authors: M. Kaleda, I. Nikishina, E. Nikolaeva, S. Arsenyeva
Journal: Annals of the Rheumatic Diseases (2020)

Background: Rituximab (RTX) is now approved only for pediatric patients (pts) 2 years of age and older with granulomatosis with polyangiitis or microscopic polyangiitis, but it has been used with success to treat another rheumatic diseases (RD) in children despite the status “of label”. Objectives: to analyze the safety of RTX in children with various RD who did not respond to conventional therapy. Methods: In our retrospective study safety data was analyzed for all pts, who received at least one infusion of RTX. The dose of RTX was established as 375 mg/m 2 of body surface area, administered by intravenous infusion once weekly for 1 to 4 weeks, depending on the CD19 lymphocyte count. Results: 81 patients with RD, who received RTX, were included: 38 (46.9%) with systemic lupus erythemathosis (SLE), 16 (19.75%) – JIA, polyarthritis (2 pts - RF negative, 14 - RF positive), 9 (11.1%) - systemic JIA (sJIA), 6 (7.4%) – systemic sclerosis (SSc), 5 (6.2%) – primary Sjogren’s syndrome (pSS), 2 (2.5%) - juvenile dermatomyositis (JDM), 4 (4.9%) - mixed connective tissue disease (MCTD ) and 1 with livedoid vasculitis (LV). Most were female – 69 (85.2%). The median age at onset – 11.6 years [interquartile range (IQR) 7.9; 14.3], median age of the starting therapy - 15.2 [IQR 12.5; 16.85] and median disease duration - 2.8 [IQR 1.0; 4.6]. 53 pts (65.4%) reported more than one course of RTX, maximum - 10. The median time between each course was 182 days [IQR 156–315]. The RTX was effective in 95% pts, ineffective in 5% (2 pts with sJIA, 2 pts with SLE and macrophage activation syndrome (MAS)). Adverse events (AE) were recorded in 23 (28.4%) pts, included upper respiratory tract infections – 7 (8.6%), urinary tract infections – 2 (2.5%), short-term infusion reactions that did not require discontinuation of therapy – 2 (2.5%), clinically insignificant neutropenia (grade I-II) – 4 (4.9%), decrease of IgG level was detected in 14 (17.5%) pts (median 5.5 g/l [IQR 4.0; 6.9]). The infection rate in pts with a low IgG level was 35.7%, in pts with neutropenia wasn’t recorded. Serious AE were recorded in 16 (19.7%) pts: sepsis – 4, pneumonia – 3, herpes zoster – 1, serious infusion reactions – 2, serious postinfusion reactions within 3 to 10 days – 4 (3 – MAS, 1 – hemorrhagic vasculitis), death – 2 pts with SLE and MAS (therapy of RTX was inefficiency). In general, various AE were registered in 55.6% of pts with sJIA, in 52.6% of pts with SLE, 50% of pts with SSc and JDM, and 80% of pts with pSS. Discontinuation of therapy due to SAE was observed in 15 pts (18.5%). Conclusion: Our study demonstrated that RTX is highly effective in children with RD, the majority with SLE, but the safety data obtained indicate the need for careful monitoring of therapy, primarily taking into account the frequency of infections. A decrease in IgG level was observed in a small proportion of pts and did not correlate with the incidence of infections. The frequency of serious infections was low. Disclosure of Interests: None declared