Dosing of Biologics in Juvenile Idiopathic Arthritis: Is the Sky the Limit?

Abstract

In the past decade, biologic therapy has been a valuable new option in the treatment of both adult and pediatric rheumatic diseases. Many patients previously refractory to anti-rheumatic drugs have shown excellent responses to biologic therapy. However, there remains a significant minority of patients who do not respond to these drugs or who lose efficacy after a period of successful treatment. Why are some patients with inflammatory arthritis primary or secondary nonresponders? Part of the problem is likely due to the heterogeneous nature of the disease. But insufficient dosing might be an issue for some patients. In drug research, dosing is evaluated by pharmaco-dynamic and pharmacokinetic (PK) models and then tested in humans for a safe dosage range and possible side effects before a drug is tested for its efficacy1,2. Unfortunately, a large proportion of medicines (50–90%) used in children are prescribed outside the terms of the drug license, i.e., off-label, which can place children at a direct risk of under- or overdosing and a delayed risk of longterm adverse effects3. The US Food and Drug Administration (FDA) has provided an incentive to US pharmaceutical companies since 1997 to study products that could be beneficial for the pediatric population3,4. The European Union (EU) enforced the Paediatric Regulation in 20075. The goals of the EU legislation are similar to those of US pediatric legislation: to improve children’s health through advancements in research and to provide a new framework for evaluating the efficacy and safety of medicines for children3,6. However, in the EU, … Address correspondence to Dr. F.H.M. Prince, Academic Medical Centre, Emma Children’s Hospital, Department of Pediatrics, H7-270, Meibergdreet 9, Amsterdam, 1105 A2, the Netherlands. E-mail: femkeprince{at}gmail.com