Efficacy, pharmacokinetics, and safety of adalimumab in pediatric patients with juvenile idiopathic arthritis in Japan

The objective of this study was to evaluate the efficacy, pharmacokinetics, and safety of adalimumab in patients with polyarticular juvenile idiopathic arthritis (JIA) in Japan. Patients aged 4 to 17 years were enrolled in a single-arm, open-label, multicentre study of adalimumab. Patients weighing <30 kg received 20 mg every other week (eow), and those ≥30 kg received 40 mg eow. Concomitant methotrexate (MTX) was allowed (≤10 mg/m(2) per week). The primary efficacy outcome was the percent of patients with American College of Rheumatology Pediatric 30 response (ACR Pedi 30) at week 16. JIA core variables, serum adalimumab concentrations, and anti-adalimumab antibodies (AAAs) were analysed. Patients were monitored for adverse events (AEs). Twenty-five patients (20 with concomitant MTX at baseline and 5 without) were enrolled: 24 patients completed 16 weeks of therapy and 22 patients completed 60 weeks. At week 16, 90 % of patients with MTX and 100 % without MTX achieved ACR Pedi 30; response rates were maintained through week 60 in 94 and 80 % of patients, respectively. Each JIA core variable improved over time. Six patients became AAA positive (two each at weeks 8, 16, and 60), some of which were transient. All six AAA-positive patients achieved ACR Pedi 30 at week 16, and four maintained that response at week 60. Six patients (all with MTX) experienced nine serious AEs (JIA, pyrexia, arthralgia, pneumonia, hepatitis B infection, pharyngitis, dehydration, pharyngeal pain, and pneumonia). In pediatric patients with polyarticular JIA in Japan, adalimumab was safe and effective for reducing disease activity for up to 60 weeks.