Challenges in the management of juvenile idiopathic arthritis with etanercept

Clare E Pain, Liza J McCann

Alder Hey Children’s NHS Foundation Trust, Eaton Road, Liverpool, UK

Abstract: Biologic agents have been designed with the help of immunological studies to target particular areas of the immune system which are thought to play a role in the pathogenesis of disease. Etanercept is a soluble anti-tumor necrosis factor alpha (TNF-α) agent licensed for the treatment of active poly-articular juvenile idiopathic arthritis (JIA) in children aged 4 to 17 years who have failed to respond to methotrexate alone, or who have been intolerant of methotrexate. The safety and efficacy of etanercept in this patient group has been established by one randomized controlled trial and several longitudinal studies. This, together with the fact that until recently etanercept was the only anti-TNF licensed in JIA, has made it the most common first choice biologic for many clinicians. However, there are still many unanswered questions about etanercept, including its efficacy and safety in different subtypes of JIA, in children under 4 years of age and in those with uveitis. There are still concerns about the long term safety of TNF antagonists in the pediatric age group and unanswered questions about increased risks of malignancy and infection. Although adult studies are useful to improve understanding of these risks, they are not a substitute for good quality pediatric research and follow-up studies. Adult trials often include greater numbers of patients. However, they evaluate a different population and drug behavior may vary in children due to differences in metabolism, growth and impact on a developing immune system. In addition, rheumatoid arthritis is a different disease than JIA. Clinicians need to carefully weigh up the risk benefit ratio of anti-TNF use in children with JIA and push for robust clinical trials to address the questions that remain unanswered. This article summarizes the evidence available for use of etanercept in children with JIA and highlights aspects of treatment in need of further research.

Keywords: juvenile idiopathic arthritis, biologic therapy, etanercept