Towards therapeutic drug monitoring of TNF inhibitors for children with juvenile idiopathic arthritis: a scoping review

Objectives Before a clinician decides whether treatment with TNF inhibition in children with JIA has failed, one should ensure adequate systemic exposure has been achieved. Therapeutic drug monitoring might allow for improved treatment outcome with lower treatment-associated costs. However, this requires understanding of the pharmacokinetic (PK) characteristics, and the pharmacokinetic/pharmacodynamic (PK/PD) relationship for children with JIA. We performed a scoping review to summarize the available literature and identify areas for future research. Methods A systematic search was conducted of the Medline, EMBASE, Web of Science and Cochrane databases as well as the clinicaltrials.gov registry. In total, 3959 records were screened and 130 publications were selected for full text assessment. Results Twenty publications were included and divided into three categories: PK (n = 9), PK/PD (n = 3) and anti-drug antibodies (n = 13). Industry involvement was significant in 14 publications. Although data are limited, systemic exposure to TNF inhibitors is generally lower in younger children but meta-analysis is not possible. The PK/PD relationship has had limited study but there is partial evidence for infliximab. Anti-drug antibodies are common, and are related to impaired clinical outcome with adalimumab and infliximab therapy. Conclusion The current knowledge about the PK and PK/PD of TNF inhibitors in the treatment of children with JIA is limited, which prevents the introduction of TDM. Re-analysis of available data from previous trials, incorporation of pharmacologic assessments into existing biorepository studies as well as new prospective PK and PK/PD trials are required to obtain this knowledge.