Background/Purpose: The first biosimilars have been approved for the treatment of juvenile idiopathic arthritis (JIA) in the last two years. To date, only a few reports exist about the experience with biosimilars in the treatment of JIA. The objectives of our study was to describe disease characteristics of young adults with JIA at biosimilar treatment start and the onset of adverse events during Treatment.

Methods: We used data collected until May 2018 from the prospective, longitudinal JuMBO (Juvenile arthritis Methotrexate/Biologics long-term Observation) cohort. JIA patients who were originally included in the pediatric register BiKeR (biologics in paediatric rheumatology) with start of a bDMARD or csDMARD will continue to be monitored in the follow-up register JuMBO into adulthood. Details on disease activity, treatment and the onset of adverse events under treatment were half-yearly reported by the treating physician.

Results: Overall, 22 JIA patients started treatment with a biosimilar (SB4: n=20, GP2015: n=1, CT-P13: n=1) in JuMBO until May 2018. The mean age and disease duration at treatment initiation was 23 years (SD=5.2) and 14.9 years (SD=7.4). Three quarters of patients had polyarticular JIA and were female. Etanercept (n=12, 55%) and MTX monotherapy (n=5, 23%) were the most recently used DMARDs before treatment start with the biosimilar. The original DMARD was discontinued due to ineffectiveness (n=7, 32%), economic reasons (n=10, 46%), an adverse event (n=1, 4%) and other reasons (n=4, 18%). The mean cJADAS10 at treatment start was 8.2 (SD=4.5) and the mean physician’s global assessment of disease activity on a numerical rating scale was 3.4 (SD=2.2). Patients were treated with the biosimilar in mean for 6 months (SD=6, median=0.5, 13 exposure year). Five patients discontinued SB4 in mean after 4 months (SD=4, median=3) due to ineffectiveness (n=2, 40%), adverse events (n=2, 40%) and after attaining an inactive disease (n=1, 20%). These patients switched to etanercept (n=3, 75%) and golimumab (n=1, 25%) after biosimilar discontinuation. Seven adverse events (rate of 53.8 events per 100 exposure years) at all and 3 serious adverse events (23.1 events per 100 exposure years, hospitalization and two medical procedures) were reported during the observation period.

Conclusion: This study gives a first overview about the use of biosimilars in young adults with JIA in Germany. Economic reasons were the primary reason for switching from the original bDMARD to the biosimilar in Germany. More patients and a longer follow-up are necessary to compare the effectiveness and safety of a biosimilar with its originator in patients with JIA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/biosimilar-use-in-young-adults-with-juvenile-idiopathic-arthritis-in-germany/