A Study of the Safety and Efficacy of CNTO 148 (Golimumab) in Children With Juvenile Idiopathic Arthritis (JIA) and Multiple Joint Involvement Who Have Poor Response to Methotrexate (GO KIDS)

• Comparison of disease flare. Flare as defined by 30% or more than 3 of the 6 ACR (American College of Rheumatology) Ped (pediatric) Core Set Variables beginning at Week 16 [ Time Frame: Week 16 through Week 48 ] [ Designated as safety issue: No ]
  

• Improvement in physical function by physician and patient assessment [ Time Frame: every 4 weeks from Week 0 to Week 48, then every 12 weeks to Week 152 ] [ Designated as safety issue: No ]
  
• Study of drug metabolism [ Time Frame: From Week 0 to Week 152 ] [ Designated as safety issue: No ]
  Serum concentrations of golimumab
  
  
• Safety of golimumab by measuring adverse events and laboratory values [ Time Frame: every 4 weeks from Week 0 to Week 48, then every 12 weeks to Week 152 ] [ Designated as safety issue: No ]
  

Approximately 170 juvenile patients will take part in the study worldwide. Each patient who is allowed to join the study is put into a group by chance (randomly), like flipping a coin. All patients will receive 30mg/m2 (milligrams per meter squared, up to 50 mg per dose) of golimumab subcutaneously (injection under the skin) every 4 weeks from Week 0 through Week 12. At Week 16, patients who have shown at least a 30 percent improvement in their signs and symptoms from when they started the study will receive either placebo (sham medicine injection) or 30 mg/m2 golimumab injections every 4 weeks from week 16 through week 48. Between Week 16 and Week 48, if the child gets markedly worse and is receiving placebo injections, they will be restarted on golimumab at the next scheduled visit and will continue on golimumab. Children who get worse between Week 16 and Week 48 and are on golimumab will be allowed to continue in the study or can leave the study. Children can leave the study at any time without question. Between the Week 48 analyses timepoint to Week 152, all patients will receive golimumab 30mg/meter squared, unless, by measurements, they have been nearly cured (clinical remission) by being on placebo, whereby they will be discontinued from the study. Patients may have a treatment change after Week 48 based on therapeutic effect. Participation in the study will be approximately 152 weeks or 3 years. Safety will be monitored throughout the study including drawing blood and looking at laboratory tests, vital signs (e.g., blood pressure), and the frequency and type of adverse events (side effects). Patients will receive golimumab 30 mg/meter squared (up to 50 mg/dose) from Week 0 to Week 12. Patients will receive either placebo or golimumab 30 mg/meter squared every 4 weeks from Week 16 through Week 48, unless they get worse, in which case placebo patients will begin golimumab again. Unless the child is nearly completely cured (clinical remission) by being on placebo, all children in the study will be on golimumab 30 mg/meter squared (up to 50 mg/dose) from Week 48 to Week 152.