Use and Effectiveness of Rituximab in Children and Young People with Juvenile Idiopathic Arthritis in a Cohort Study in the United Kingdom

Objectives: Rituximab may be a treatment option for children and young people with juvenile idiopathic arthritis (JIA), although not licensed for this indication. The aim of this current study was to describe rituximab use and outcomes among children with JIA. Methods: This analysis included all JIA patients within the UK Biologics for Children with Rheumatic Diseases (BCRD) study starting rituximab. Disease activity was assessed at rituximab start and at follow-up. Total number of courses each patient received was assessed. Serious infections and infusion reactions occurring following rituximab were reported. Results: Forty-one JIA patients starting rituximab were included, the majority polyarthritis: polyarthritis RF negative (n=14, 35%), polyarthritis RF positive (n=13, 33%), extended oligoarthritis (n=9, 23%). Most were female (80%), median age 15 years (IQR 12, 16), median disease duration 9 years (IQR 5, 11). Median improvement in cJADAS from rituximab start was 9 units (n=7; IQR -14, 2). Over half reported >1 course of rituximab. Median time between each course was 219 days (IQR 198, 315). During follow-up, 17 (41%) patients reported switching to another biologic; tocilizumab (n=8), abatacept (n=6), tumour necrosis factor inhibitor (TNFi; n=3). Three patients (7%) reported a serious infection on rituximab (rate of first serious infection 6.2/100 person-years). Four patients (10%) reported an infusion reaction. Conclusions: This real-world cohort of children with JIA, the majority with polyarticular or extended oligoarticular JIA, has shown rituximab may be an effective treatment option for children who do not respond to TNFi, with a low rate of serious infections on treatment.