Safety and efficacy of once weekly etanercept 0.8 mg/kg in a multicentre 12 week trial in active polyarticular course juvenile idiopathic arthritis.

Objectives: Etanercept, a recombinant TNF receptor fusion protein, has been approved for the treatment of resistant polyarticular course juvenile idiopathic arthritis at a dosage of 0.4 mg/kg twice weekly in children older than 4 years. In adult patients, efficacy and safety of etanercept 25 mg twice weekly was comparable with 50 mg once weekly. Therefore, safety and efficacy of etanercept once weekly 0.8 mg/kg up to 50 mg s.c. was evaluated in a 3 month open label trial.

Methods: Twenty patients 4 to 17 years old received 0.8 mg of etanercept per kilogram of body weight subcutaneously once weekly for 3 months in an open multicentre trial. Active polyarticular disease was defined by the presence of five or more active joints with swelling, alternatively with pain or tenderness combined with limitation of motion. Safety assessments were based on adverse events (AEs) reports. Efficacy was assessed using the PedACR30/50/70 criteria.

Results: At the start of treatment the patients showed high disease activity. A rapid reduction of all disease activity parameters was observed. A PedACR30/50/70 response was reached by 75%/35%/10% of patients after 4 weeks, 90%/75%/35% after 8 weeks and 95%/75%/75% after 12 weeks of treatment. There were 37 AEs, none of them serious, with injection site reactions and minor infections being the most frequent. There was no drop out. Long-term follow-up of the patients will be carried out in the German JIA Registry.

Conclusion: Treatment with etanercept once weekly using a double dosage leads to a significant improvement of disease activity in patients with active polyarticular course juvenile idiopathic arthritis and is well tolerated.