Etanercept in the treatment of disease-modifying anti-rheumatic drug (DMARD)-refractory polyarticular course juvenile idiopathic arthritis: experience from Japanese clinical trials

Efficacy, safety, and pharmacokinetics results from 4 studies—3 open-label (OL) and 1 randomized double-blind (DB)—have provided data for approval of etanercept for treatment of disease-modifying anti-rheumatic drug (DMARD)-refractory juvenile idiopathic arthritis (JIA) in Japan. Results from the 3 shorter-term (2 OL and 1 DB) studies are reported here. Subjects (4–17 years) enrolled in the OL studies had active JIA, i.e. ≥5 swollen joints and ≥3 joints with limitation of motion and pain or tenderness. Subjects enrolled in the primary OL study received etanercept 0.4 mg/kg subcutaneously twice weekly; in the lower-dose OL study subjects received etanercept 0.2 mg/kg. Subjects in the primary OL study who completed ≥48 weeks could continue into a 12-week DB dose-down extension study in which subjects received etanercept 0.4 or 0.2 mg/kg twice weekly. The primary endpoint in all 3 studies, i.e. 30% improvement in the American College of Rheumatology criteria for JIA (ACR Pedi 30) at 12 weeks, was achieved by ≥80% of subjects by week 2 and sustained to week 12. Common adverse events reported were injection site reactions, nasopharyngitis, and gastroenteritis. These results provide further evidence that etanercept is effective therapy for DMARD-refractory polyarticular JIA patients.