An Extension Study to Demonstrate Long-Term Efficacy and Safety of CT-P13 When Co-administered With Methotrexate in Patient With Rheumatoid Arthritis Who Were Treated With Infliximab (Remicade or CT-P13) in Study CT-P13 3.1

CT-P13(3mg/kg) administered as a 2-hour IV infusion per dose co-administered with methotrexate between 12.5 to 25 mg/week, oral or parenteral dose (dose and route must be maintained from Study CT-P13 3.1 and be maintained from the beginning to the end of the extension study) and folic acid(≥5mg/week, oral dose)