Comparable long-term outcomes with biosimilar and originator adalimumab in juvenile idiopathic arthritis: a multicenter cohort study

Background Real-world evidence on biosimilar adalimumab in juvenile idiopathic arthritis (JIA) remains limited. We compared the effectiveness, treatment persistence, and safety of biosimilar and originator adalimumab.Methods This multicenter retrospective cohort study included children with JIA treated with biosimilar or originator adalimumab for ≥24 weeks. Disease activity was assessed using the Juvenile Arthritis Disease Activity Score-27 (JADAS-27) and, in enthesitis-related arthritis (ERA), the Juvenile Spondyloarthritis Disease Activity Index (JSpADA). Treatment persistence and adverse events were compared.Results 129 patients were analyzed (originator product [OP], n = 86; biosimilar product [BP], n = 43; ABP 501, n = 39; GP2017, n = 4). Prior biologic exposure was higher in OP (p = 0.007), and time to adalimumab initiation was longer in OP (p = 0.015). JADAS-27 scores were higher in BP at treatment initiation (T0) and month 3 (T3) (p = 0.029 and p = 0.027) but not thereafter. JSpADA scores were similar overall. Treatment persistence was similar between groups (p = 0.080). Remission ≥6 months was more frequent in OP (p = 0.039), whereas drug-free remission and adverse event rates were similar.Conclusions Biosimilar adalimumab demonstrated comparable long-term outcomes to the originator, although baseline differences between groups should be considered.