Safety and Efficacy of Etanercept (Recombinant Human Tumor Necrosis Factor Receptor Fusion Protein [TNFR:Fc]) in Children With Juvenile Rheumatoid Arthritis (JRA)

Inclusion Criteria:

* Diagnosis of JRA by the American College of Rheumatology (ACR) criteria.
* Disease course must be polyarticular with disease duration long enough to have been given an adequate trial of non-steroidal anti-inflammatory drugs (NSAIDs) and low-dose methotrexate at a dose of at least 10 mg/m²/week
* Continuing active disease, defined as ≥ 5 swollen joints and ≥ 3 joints with limitation of motion accompanied by pain, tenderness or warmth.
* Disease refractory to methotrexate or intolerant of methotrexate.
* Have not received disease-modifying anti-rheumatic drugs (DMARDs) within 28 days prior to enrollment.
* Have not received methotrexate within 14 days prior to dosing of study drug.

Exclusion Criteria:

* Pregnant or nursing female
* Functional class IV by ACR criteria
* Unable to meet concomitant medication restrictions
* Intraarticular corticosteroid injection within 4 weeks prior to enrollment
* Clinically significant deviations from normal, defined as:

  * thrombocytopenia; platelet count \< 100,000/cmm
  * leukopenia; total white cell count \< 4000 cells/cmm
  * neutropenia; neutrophils \< 1000 cells/cmm
  * hepatic transaminase levels \> two times the upper limit of normal (ULN)
  * serum bilirubin \> 2 times ULN
  * creatinine clearance \< 90 mL/min/1.73 m² body surface area (BSA) and/or a glomerular filtration rate (GFR) \< 90 mL/min/1.73 m² BSA.
  * known human immunodeficiency virus (HIV), hepatitis B surface antigen positivity, or hepatitis C positivity.
  * anti-double-stranded deoxyribonucleic acid (dsDNA) antibodies or anti-cardiolipin antibodies present.
* Previously received antibody to TNF, antibody to cluster of differentiation (CD)4, or diphtheria interleukin (IL)-2-fusion protein (DAB-IL-2)
* Participated in a study of an investigational drug or biologic requiring informed consent within 3 months prior to study entry.
* Any concurrent medical condition which would, in the investigator's opinion, compromise the patient's ability to tolerate the study drug or make the patient unable to cooperate with the protocol.
* History of or current psychiatric illness that would interfere with ability to comply with protocol requirements or informed consent.
* History or drug or alcohol abuse that would interfere with ability to comply with protocol requirements