Switch to Anti-TNF Biosimilar Well-Tolerated in Juvenile Idiopathic Arthritis

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Disease activity was similar between patients with JIA undergoing a non-medical biological switch and those continuing the originator anti-TNF product.

A matched comparative effectiveness analysis found no evidence that switching from an anti-tumor necrosis factor (TNF) originator to a biosimilar product stopped treatment, or worsened disease activity, in patients with juvenile idiopathic arthritis (JIA).1

In the UK JIA Biologics Register, approximately three-quarters of patients remained on biosimilar treatment, with only 9% switching back to the originator, after 1 year, supporting the tolerability of non-medical switching in children and young individuals with JIA.

“The results of this study show that switching from an originator to a biosimilar in a non-medical switch does not result in a significant change in disease activity or alter whether patients subsequently stop treatment, compared with those who continue the originator therapy, providing reassurance to patients and their families, as well as healthcare professionals,” wrote the investigative team, led by Lianne Kearsley-Fleet, PhD, Center for Musculoskeletal Research, The University of Manchester.

Initial treatment with conventional synthetic disease-modifying antirheumatic drugs (DMARDs) or steroid or non-steroidal anti-inflammatory drugs can be unsuccessful—biological therapies were first introduced into care in the early 2000s. As the original patents for biological DMARDs have expired, biosimilar products have been manufactured and have demonstrated equivalent efficacy in Phase 3 clinical trials.

In the UK, biosimilars have been licensed in JIA since 2016. Given the competitive pricing of biosimilars, many patients have been switched from an originator for cost-saving purposes, deemed as a ‘non-medical switch.’

However, given the lack of data on clinical outcomes after switching from an originator to a biosimilar in JIA, Kearsley-Fleet and colleagues explored the impact of switching from an anti-TNF originator to a biosimilar on drug survival and disease activity, compared with those who continued on an originator product.

All children and young adults in the UK JIA Biologics Register treated with anti-TNF therapy until July 2023 were identified and eligible for inclusion in the analysis. Those with systemic JIA, or who started treatment ≥6 months before registration were excluded from the study.

Each patient switching to an anti-TNF biosimilar was matched 1:1 to a patient continuing the originator product, based on characteristics at the start of the originator treatment, including age, sex, disease duration, and line of therapy. A Cox proportional hazards model evaluated whether drug persistence differed between those who switched to a biosimilar and those who continued the originator.

A 71-joint juvenile arthritis disease activity score (JADAS-71) was calculated at the index date, or 6 months after the index date. The proportion of patients with a clinically notable worsening score (by ≥1.7 units) after 6 months was compared across cohorts.

Overall, 224 children and young individuals (62% female) with non-systemic JIA were identified as switched from a biological originator to a biosimilar product from January 2017 to July 2023. Most patients (64%) who switched to a biosimilar were originally on adalimumab, while 25% were on etanercept and 11% were on infliximab.

Among this population, 164 patients were matched successfully to a patient continuing on the originator product. Upon analysis, Kearsley-Fleet and colleagues observed no evidence the switching cohort was more likely to stop treatment than those continuing the originator (hazard ratio [HR], 1.46; 95% CI, 0.93–2.30).

For patients (n = 51) who stopped the biosimilar treatment, 18 (35%) switched back to the originator product, including 14 patients in the first year. Meanwhile, 28 (55%) patients began a different biological therapy, and 5 (10%) patients discontinued treatment altogether by the final follow-up.

In matched patients with available disease activity (n = 87), Kearsley-Fleet identified no evidence of clinically important worsening of disease activity by JADAS-71 after 6 months (odds ratio [OR], 0.71; 95% CI, 0.34 - 1.51; P = .38).

“The results from this analysis will be reassuring to clinicians, patients, and their families considering a non-medical switch, and suggests good tolerance of non-medical switching in this patient population,” investigators wrote.


  1. Kearsley-Fleet L, Baildam E, Beresford MW, et al. Outcomes after anti-tumour necrosis factor originator to biosimilar switching in children and young people with juvenile idiopathic arthritis in the UK: a national cohort study. Lancet Rheumatol. Published online June 3, 2024. doi:10.1016/S2665-9913(24)00087-0