Background/Purpose: Selective peripheral B-cell depletion by rituximab (RTX) is a relatively recent advance in rheumatic diseases. RTX is an approved treatment in RA. Although very few studies have examined RTX in JIA, evidence in adults for its better effectiveness in seropositive compared to seronegative RA, may have led to reluctance for the use of RTX in RF negative poly-articular JIA. The aim of this study was to describe the use and outcomes among children with JIA, including RF negative polyarticular subtype treated with RTX in the UK.

Methods: The UK Biologics for Children with Rheumatic Diseases (BCRD) study is a prospective register capturing information on JIA patients treated with biologic therapies. Demographic, disease information, disease activity before and after (median 5.5 months) rituximab (2 doses at 750mg per m², 2 weeks apart) and adverse events were analysed. Effectiveness of RTX was evaluated from the change in core set measures. The ACR pediatric (Pedi) criteria were applied for cases with complete information on disease activity.

Results: A total of 49 JIA patients treated with RTX were identified, 80% female, median (IQR) age at disease onset and start of RTX was 5 (3, 7) years and 15(6, 12) years respectively. RF (-) polyarticular was the commonest subtype (n=20) followed by RF (+) polyarthritis (n=12), oligoarticular extended (n=9), oligoarticular persistent (n=4), psoriatic (n=2) and 1 patient each with systemic-onset and enthesitis related arthritis. Most (n=46) had received treatment with at least 1 prior biologic before RTX, an anti-TNF being the most common (n=42), 16 received concomitant MTX. Most children started RTX following inadequate response to prior therapy (n=45). There were significant improvements in active and limited joint counts, physician assessment of disease activity and ESR; median functional ability (CHAQ score) did not improve (table1). The ACR Pedi criteria could be applied only in 20 children due to missing individual data items. ACR- Pedi30/50/70 were achieved in 65%, 56% and 20% overall, and in 73%, 56% and 43% of RF (-) polyarthritis. Most did not experience any adverse events related to RTX over the first 6 months of therapy, with 2 reported infusion reactions and 2 infections (1 serious).

Conclusion: In this small but varied JIA cohort, RTX therapy resulted in meaningful improvements in physician recorded outcomes in many children with JIA, including those with RF (-) arthritis with limited adverse effects, suggesting RTX may be an effective treatment option for children with subtypes other than RF(+) polyarthritis. Disability scores did not improve overall although this may reflect the severity of disease in this longstanding disease cohort.  

Table 1. Disease activity before and after RTX, and previous/concomitant therapies.