Outcomes following anti-TNF originator to biosimilar switching in children and young people with Juvenile Idiopathic Arthritis (JIA)

Objectives: For cost-saving, children and young people with JIA are being switched (non-medical) from biologic originators to biosimilars. This analysis investigates what happens to those who switch from an anti-TNF originator to biosimilar, regarding drug survival and disease activity, compared with a matched-cohort who remain on originator.

Methods: Includes all patients in the UK JIA Biologics Register (cohort study) switching directly from an anti-TNF originator to biosimilar of the same product. All patients were matched (age, gender, disease duration, calendar-year, line of therapy, ILAR) to patients receiving originator. For those matched successfully, Cox-proportional hazard models assessed whether drug persistence differed between those who switched versus those remaining on originator. Change in JADAS-71, and proportion worsening (by ≥1.7units), after six-months was compared between cohorts. This analysis was designed to address a priority research area set by our patient-partners.

Results: 224 patients switched from originator to biosimilar; 143(63%) adalimumab, 56(25%) etanercept, 25(11%) infliximab. Of these, 164 patients were matched successfully to those remaining on originator. There was no evidence that patients switching were more likely to stop treatment compared with those remaining on originator: hazard ratio 1.44 (95%CI:0.91-2.26). Of the 50 biosimilar patients who stopped treatment, 18 switched-back to the originator (14 in year one), 27 started a different biologic, and five remained off treatment at last follow-up. Of the 87 matched-patients with available disease activity, there was no evidence that JADAS-71 worsened more after six-months: odds ratio 0.71 (95%CI:0.34-1.52).

Conclusions: In this large matched comparative effectiveness analysis, many children and young people with JIA have switched from originators to biosimilars. Disease activity remained similar between patients switching versus those remaining on originator. Three-in-four were still receiving their biosimilar after one year, with switching back to originator uncommon, 9% after one year, suggesting good tolerability of non-medical switching in this patient population.