ß-SPECIFIC 4 Patients: Study of Pediatric EffiCacy and Safety wIth FIrst-line Use of Canakinumab

Inclusion Criteria: Cohort 1: • Patients who are receiving canakinumab treatment (4 mg/kg every 4 weeks) for Systemic Juvenile Idiopathic Arthritis (SJIA) and have inactive disease at the last visit in Study CACZ885G2301E1 Cohort 2: * Confirmed diagnosis of SJIA as per International League Against Rheumatism (ILAR) definition that must have occurred at least 2 months prior to enrollment with an onset of disease \< 16 years of age. * Active SJIA defined as having 2 or more of the following: * Documented spiking, intermittent fever (body temperature \> 38°C) for at least 1 day within 1 week before first canakinumab dose; * At least 2 joints with active arthritis * C-reactive protein (CRP) \> 30 mg/L (normal range \< 10 mg/L) * Rash due to SJIA * Serositis * Lymphadenopathy * Hepatosplenomegaly * Negative TB screen (QuantiFERON or, if required by local guidelines, Purified Protein Derivative). Exclusion Criteria: * With active or recurrent bacterial, fungal or viral infection at the time of enrollment, including patients with evidence of Human Immunodeficiency Virus (HIV) infection, Hepatitis B and Hepatitis C infection. * With underlying metabolic, renal, hepatic, infectious or gastrointestinal conditions which in the opinion of the investigator immunocompromises the patient and /or places the patient at unacceptable risk for participation. * With neutropenia (absolute neutrophil count \< 1500/mm3) at screening.