Approximately 170 juvenile patients will take part in the study worldwide. 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 be randomized to receive either placebo (sham medicine injection) or 30 mg/m2 of golimumab injections every 4 weeks from week 16 through week 48. If a patient gets markedly worse and is receiving placebo injections, they will be restarted on golimumab at the next scheduled visit and will continue on golimumab. Patients can leave the study at any time without question. Between the Week 48 analyses timepoint to Week 144, which is subsequently amended to Week 248, 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 change in background treatment after Week 48 based on therapeutic effect. Patients will continue active treatment after Week 48 in a long-term extension until Week 144, which is subsequently amended to Week 248. All patients will receive their fixed dose of commercial methotrexate throughout the study duration. Safety will be monitored up to 152 week, which is subsequently amended to 256 weeks including drawing blood and looking at laboratory tests, vital signs (eg, blood pressure), and the frequency and type of adverse events (side effects).
