Long-term open-label preliminary study of the safety and efficacy of leflunomide in patients with polyarticular-course juvenile rheumatoid arthritis.

OBJECTIVE: To obtain preliminary data regarding the efficacy and long-term safety of leflunomide in patients with refractory polyarticular-course juvenile rheumatoid arthritis (JRA).
METHODS: Twenty-seven patients were entered into the initial 26-week open-label study of leflunomide therapy; 17 entered the extension phase (maximum 107 weeks). Mean disease duration at study entry was 7.0 years. All patients had >or=5 joints with active arthritis and had received methotrexate for a mean of 36.0 months. Following a loading dose, patients initially received leflunomide at a dosage of 10 mg/1.73 m(2)/day, which could be increased to 20 mg/1.73 m(2)/day (maximum 20 mg/day) beginning at week 8. The primary efficacy outcome was the American College of Rheumatology (ACR) Pediatric 30 (Pedi 30) criteria for improvement. Last observation carried forward (LOCF) analysis was used, and all patients were entered into an intent-to-treat analysis. Intraarticular corticosteroids (maximum of 2 in the initial 26 weeks) were allowed, but no new disease-modifying antirheumatic drug or change in nonsteroidal antiinflammatory drug was allowed throughout the study.
RESULTS: Seventeen of the 27 patients (63%) completed the initial 26-week study. Fourteen patients (52%) met the ACR Pedi 30 response criteria at week 26. Seventeen patients entered into the extension phase (13 who met response criteria and 4 who failed to meet response criteria but decided to continue). Nine of the 17 patients (53%) who entered the extension phase either completed all 30 months of study or the study ended prior to the month 30 visit. Five patients withdrew because of failure to maintain efficacy, 2 withdrew their consent, and 1 withdrew because of an adverse event. Using LOCF analysis, 65% of patients met ACR Pedi 30 response criteria at 1 year and 2 years (weeks 50 and 106, respectively) and 53% at the end of the study. Good response rates were also seen using ACR Pedi 50 and ACR Pedi 70 criteria (47% and 24% at week 106, respectively).
CONCLUSION: In this open-label study of JRA patients who either failed to respond to, or were intolerant of, methotrexate, the majority met the ACR Pedi 30 response criteria at week 26. The response was durable, since 53% of patients who entered into the extension phase (maximum 30 months) responded at the end of this phase. Our findings support the further study of the role of leflunomide in the treatment of polyarticular-course JRA.