The purpose of this study is to evaluate the pharmacokinetics (the study of the way a drug enters and leaves the blood and tissues over time) of golimumab administered intravenously (IV) to pediatric participants with polyarticular (affects 5 or more joints) juvenile (an onset before age 16) idiopathic (of unknown cause) arthritis (joint pain) (pJIA) manifested by greater than or equal to (\>=) 5 joints with active arthritis despite methotrexate (MTX) therapy for \>= 2 months.
This is a single arm, Open-label (all people know the identity of the intervention), multi-center (when more than one hospital or medical school team work on a medical research study) study to determine the pharmacokinetics (the study of the way a drug enters and leaves the blood and tissues over time), efficacy (effectiveness) and safety of intravenous golimumab in participants with pJIA despite current treatment with methotrexate (MTX). The study will consist of 3 parts: Screening Phase (6 weeks); an Open-label Treatment Phase (consists of golimumab and MTX treatment for 52 weeks, wherein after Week 28, MTX dose change is allowed); Long-term Extension Phase (after Week 52 through Week 252) and Extended Treatment Period (after week 252). The maximal study duration for a participant will not exceed 832 weeks. All the eligible participants will be administered golimumab IV infusion and commercial MTX. Blood samples will be collected for evaluation of pharmacokinetics of study treatment. Participants' safety will be monitored throughout the study.
Golimumab 80 mg/m\^2 IV infusion at Weeks 0, 4, and every 8 weeks through Week 244. At Week 252, participants who meet the criteria for the optional Extended Treatment Period (ETP) may continue treatment with golimumab 80 mg/m\^2 every 8 weeks after completion of the Week 252 assessments.
Methotrexate BSA-based dose (10 to 30 mg/m\^2 per week for participants with BSA \<1.67 m\^2, or minimum of 15 mg/week for participants with BSA \>=1.67 m\^2) weekly at least through Week 28.
Buenos Aires, Argentina
Rosario, Argentina
San Miguel de Tucumán, Argentina