WA28029 Estudio de frecuencia de dosis disminuida en participantes con artritis juvenil sistémica que experimentan anomalías de laboratorio durante el tratamiento con RoActemra/Actemra (tocilizumab) (ARTHUR)

PART 1 and 2

• Children 2 to 17 years of age inclusive at screening
• Systemic juvenile idiopathic arthritis (sJIA) according to International League of Associations for Rheumatology (ILAR) classification (2001) and sJIA symptoms lasting for at least 1 month since diagnosis of sJIA
• Must meet one of the following:
• Not receiving methotrexate (MTX) or discontinued MTX at least 4 weeks prior to baseline visit, or
• Taking MTX for at least 12 weeks immediately prior to the baseline visit and on a stable dose of less than or equals (</=) 20 milligrams per meter square (mg/m^2) for at least 8 weeks prior to the baseline visit, together with either folic acid or folinic acid according to local standard of care
• Participants entering Part 1 who are naive to TCZ therapy must also meet the following inclusion criterion:
• History of inadequate clinical response (in the opinion of the treating physician) to Non steroidal Anti-Inflammatory Drugs (NSAIDs) and corticosteroids PART 2
• Juvenile Arthritis Disease Activity Score (JADAS) -71 score of 3.8 or less and absence of fever (related to sJIA) at screening and baseline
• Neutropenia, thrombocytopenia, or elevated Alanine transaminase/Aspartate transaminase (ALT/AST) previously experienced on the labeled dose (Q2W) of RoActemra/Actemra at any time
• Not currently receiving oral corticosteroids, or taking oral corticosteroids at a stable dose for a minimum of 2 weeks prior to baseline visit at no more than 10 milligrams per day (mg/day) or 0.2 miiligrams per kilogram per day (mg/kg/day), whichever is less
• Not taking (NSAIDs), or taking no more than 1 type of NSAID at a stable dose for a minimum of 2 weeks prior to the baseline visit, with the dose being less than or equal to the maximum recommended daily dose

• Wheelchair bound or bedridden
• Any other auto-immune, rheumatic disease, or overlap syndrome other than sJIA
• Pregnant or lactating, or intending to become pregnant during study conduct and up to 6 months after the last administration of study drug
• Any significant concurrent medical or surgical condition which would jeopardize the participant's safety or ability to complete the trial
• History of significant allergic or infusion reactions to prior TCZ infusion, and/or presence of anti-TCZ antibodies at screening
• Inborn conditions characterized by a compromised immune system
• Known Human Immunodeficiency Virus (HIV) infection or other acquired forms of immune compromise
• History of alcohol, drug, or chemical abuse within 6 months of screening
• Evidence of serious uncontrolled concomitant diseases, including but not limited to the nervous, renal, hepatic, or endocrine systems
• Any active acute, subacute, chronic or recurrent bacterial, viral, or systemic fungal infection
• History of atypical tuberculosis (TB)
• Active TB requiring treatment within 2 years prior to the screening visit
• Positive purified protein derivative (PPD) at screening
• Any major episode of infection requiring hospitalization or treatment during screening or treatment with IV antibiotics completing within 4 weeks of the screening visit or oral antibiotics completing within 2 weeks of the screening visit
• History of reactivation or new onset of a systemic infection within 2 months of the screening visit
• Positive for hepatitis B or hepatitis C infection
• Chronic hepatitis, viral or pulmonary disease
• Significant cardiac or pulmonary disease
• History of or current cancer or lymphoma
• Uncontrolled diabetes mellitus
• History of or concurrent serious gastrointestinal disorders
• History of macrophage activation syndrome (MAS) within 3 months prior to screening visit