This is a double-blind, Phase III study to evaluate the efficacy, safety and PK of MRA in patients with sJIA.

Inclusion criteria

• Patients diagnosed as having systemic JIA based on the International League of Associations for Rheumatology criteria (1997)
• Patients between 2 and 19 years of age
• Patients who are under 16 years of age at onset
• Patients who have been treated with corticosteroids (continued treatment for 3 months or longer at a dose of ≥0.2 mg/kg as prednisolone equivalent) but who failed to respond adequately or in whom treatment could not be continued or the dose could not be increased due to adverse drug reactions

Exclusion criteria

• Patients who have been treated with infliximab or etanercept within 12 weeks before treatment with the investigational product

• Patients who have received the following treatments within 4 weeks before treatment with the investigational product

  1. Surgical treatment (e.g., operation)
  2. Plasma exchange therapy"