An Open-label, Ascending, Repeated Dose-finding Study of Sarilumab in Children and Adolescents With Polyarticular-course Juvenile Idiopathic Arthritis (pcJIA)

Inclusion criteria : * Male and female participants aged ≥2 and ≤17 years (or country specified age requirement) at the time of the screening visit. * Diagnosis of rheumatoid factor-negative or rheumatoid factor positive polyarticular Juvenile Idiopathic Arthritis (JIA) subtype or oligoarticular extended JIA subtype according to the International League of Associations for Rheumatology (ILAR) 2001 Juvenile Idiopathic Arthritis Classification Criteria with at least 5 active joints as per American College of Rheumatology (ACR) definition for "active arthritis" at Screening * Participant with an inadequate response to current treatment and considered as a candidate for a biologic disease modifying antirheumatic drug (DMARD) as per investigator's judgment Exclusion criteria: * Body weight \<10 kg or \>60 kg for participants enrolled in the 3 ascending dose cohorts, then body weight \<10 kg for participants subsequently enrolled at the selected dose-regimen. * If nonsteroidal anti-inflammatory drugs (NSAIDs) \[including cyclo oxygenase-2 inhibitors (COX-2)\] taken, dose stable for \<2 weeks prior to the baseline visit and/or dosing prescribed outside of approved label. * If non-biologic DMARD taken, dose stable for \<6 weeks prior to the baseline visit or at a dose exceeding the recommended dose as per local labeling. * If oral glucocorticoid taken, dose exceeding equivalent prednisone dose 0.5 mg/kg/day (or 30 mg/day) within 2 weeks prior to baseline. * Use of parenteral or in…