Abatacept as Monotherapy and in Combination With Methotrexate in Patients With Juvenile Idiopathic Arthritis: Analysis of 2 Phase III Trials.

OBJECTIVE: To describe the efficacy and safety data of children with polyarticular-course juvenile idiopathic arthritis (pcJIA) treated with abatacept (ABA) + methotrexate (MTX) or ABA monotherapy when prior MTX use was either ineffective or not tolerated. METHODS: Posthoc analysis of 2 phase III trials of subcutaneous (SC) and intravenous (IV) ABA over 2 years in patients with pcJIA (aged 2-17 years). Patients were stratified by treatment with ABA + MTX or ABA monotherapy and further by prior biologic use. Efficacy outcomes included JIA-American College of Rheumatology (JIA-ACR) responses, Juvenile Arthritis Disease Activity Score in 27 joints using C-reactive protein (JADAS27-CRP), and safety. Descriptive pharmacokinetic analyses were also performed. RESULTS: Efficacy responses (JIA-ACR and JADAS27-CRP) were similar between patients receiving ABA + MTX (n = 310) or ABA monotherapy (n = 99) and persisted over 2 years. Clinical response rates were similar in biologic-naïve patients and prior biologic users; this was independent of MTX use. Across both studies, ABA + MTX and ABA monotherapy displayed similar safety profiles. Pharmacokinetic results revealed similar minimum steady-state trough ABA concentrations between studies. Further, baseline MTX did not influence ABA clearance and was not a significant predictor of JIA-ACR responses. CONCLUSION: ABA monotherapy (SC and IV) was effective and well tolerated in children with pcJIA when prior MTX use was ineffective or not tolerated. Treatment effects of ABA appear to be independent of MTX coadministration. Consequently, ABA monotherapy can be considered for those with prior biologic therapy if MTX use is inappropriate. (ClinicalTrials.gov: NCT01844518 and NCT00095173).