Switching children and young people with juvenile idiopathic arthritis (JIA) from anti-tumor necrosis factor (TNF) originators to biosimilars showed similar disease activity and drug persistence compared to those continuing the originators, with a low rate of switching back, according to a study published in The Lancet Rheumatology. The findings support the practice of non-medical switching, offering reassurance to patients, families, and clinicians.
Study Design and Patient Population
The study utilized data from the UK JIA Biologics Register, focusing on children younger than 16 years with JIA initiating biological or targeted synthetic disease-modifying antirheumatic drug therapy by July 7, 2023. Researchers compared outcomes in 224 children with non-systemic JIA who transitioned from an originator to a biosimilar between January 1, 2017, and July 7, 2023, with a matched cohort continuing originator therapy. The primary outcome was drug survival, assessed using Kaplan-Meier estimates and Cox proportional hazard models. Disease activity was measured using the Juvenile Arthritis Disease Activity Score (JADAS-71).
Comparable Effectiveness and Drug Persistence
The analysis revealed no significant difference in treatment discontinuation rates between the biosimilar and originator groups (HR, 1.46; 95% CI, 0.93-2.30). At one year post-switch, 76% of biosimilar patients and 87% of originator patients remained on therapy. At two years, these rates were 64% and 70%, respectively. Furthermore, there was no clinically significant worsening of disease activity in those who switched to biosimilars (OR, 0.71; 95% CI, 0.34-1.51).
Reasons for Discontinuation and Switching Back
Of the 51 patients who stopped biosimilar treatment, 35% switched back to the originator, with a median time to restart of 0 days (IQR, 0-14). Another 55% switched to a different biological therapy due to ineffectiveness. Injection-related issues, such as stinging or painful injections, were reported by 22% of those who discontinued biosimilars, with 8 patients returning to the originator.
Context of Biosimilar Use in the UK
In the UK, approximately 12,000 children and young people are affected by JIA. Patients have access to multiple approved adalimumab, infliximab, and etanercept biosimilars. The UK’s Medicines and Healthcare products Regulatory Agency has declared all biosimilars interchangeable with their reference agents upon approval. However, previous studies have indicated a lack of understanding and confidence in biosimilars among some providers and patients.
Expert Commentary
The study authors noted, "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."
Study Limitations
The authors acknowledged several limitations, including potential misclassification of disease activity, difficulty interpreting unadjusted JADAS-71 changes, unmatched patients with rare characteristics, unmeasured confounders, and low patient numbers limiting drug-specific analyses.
