Preventing Extension of Oligoarticular Juvenile Idiopathic Arthritis JIA (Limit-JIA)

To be eligible for this trial, participants must meet all of the following criteria in order to be include in the study:

1. Age ≥ 2 years old and ≤16.5 years old
2. Clinical diagnosis of JIA by a pediatric rheumatologist within the past 6 months
3. Arthritis affecting ≤4 joints between disease onset and enrollment
4. Enrollment in the CARRA Registry
5. Participants of childbearing potential must agree to remain abstinent or agree to use an effective and medically acceptable form of birth control from the time of written or verbal assent to at least 66 days after taking the last dose of study drug.
6. Weight ≥50 kg (Canadian Sites only) ¹ Enrollment is defined as having signed consent to participate in the Limit-JIA study.

The presence of any of the following will exclude a study participant from inclusion in the study:

1. 1. Systemic JIA as defined by 2004 ILAR criteria1
2. Sacroiliitis (clinical or radiographic)
3. Inflammatory bowel disease (IBD)
4. History of psoriasis or currently active psoriasis
5. History of uveitis or currently active uveitis
6. Prior treatment with systemic medication(s) for JIA (e.g. one or more of the following: DMARD or biologic medication)
7. Current or previous (within 30 days of enrollment) treatment with systemic glucocorticoids (A short course of oral prednisone [≤ 14 days] is allowed)
8. History of active or chronic liver disease
9. Chronic or acute renal disorder
10. AST (SGOT), ALT (SGPT) or BUN >2 x ULN (upper limit of normal) or creatinine >1.5 mg/dL or any other laboratory abnormality considered by the examining physician to be clinically significant within 2 months of the enrollment visit
11. Presence of any medical or psychological condition or laboratory result which would make the participant, in the opinion of the investigator, unsuitable for the study
12. Participation in another concurrent clinical interventional study within 30 days of enrollment
13. Known positive human immunodeficiency virus (HIV)
14. Received a live virus vaccine within 1 month of the baseline visit
15. Current or prior positive Purified Protein Derivative (PPD) test or Quantiferon Gold TB
16. Pregnant, breast feeding, or planned breast feeding during the study duration
17. Planned transfer to non-participating pediatric rheumatology center or adult rheumatologist in the next 12 months
18. Active malignancy of any type or history of malignancy
19. Chronic or active infection or any major episode of infection requiring hospitalization or treatment with intravenous (IV) antibiotics within 30 days or oral antibiotics within 14 days prior to screening
20. Primary language other than English or Spanish
21. Positive for Hepatitis B surface antigen or core antibody
22. <10 Kg in weight
23. If a potential subject has symptoms consistent with COVID-19 and/or known COVID-19 exposure at screening, it is recommended that the site follow CDC guidance regarding testing and quarantine requirements. The subject can be re-screened when there is no longer concern for active infection. A subject with a positive COVID -19 test may be re-screened.