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)
