Evaluation of adalimumab tapering regimens in children and adolescents with juvenile idiopathic arthritis in remission: a simulation study

Adalimumab (ADM) in children with juvenile idiopathic arthritis (JIA) is usually dosed using fixed weight-based bands (label dosing: 20 mg for < 30 kg, 40 mg for ≥ 30 kg) every other week (EOW). This has been shown to result in higher exposure after remission than targeted in adult patients with rheumatic diseases (trough concentrations of 2–8 mg/L) suggesting possibility of treatment adjustments and tapering, particularly in children weighing 30 to 50 kg. A pharmacometric simulation study was performed to evaluate different ADM dosing regimens supported by therapeutic drug monitoring (TDM) to provide insights for JIA management in remission. This simulation study used a previously established pharmacokinetic ADM model. Simulation scenarios included dose reduction to 30 mg in children 30 to 50 kg and interval extension from 14 to 21 or 28 days. To further personalize ADM dosing and avoid exposure above predefined target range, TDM-guided tapering within mentioned simulation scenarios was investigated, i.e., adjusting dosing interval in children and adolescents whose ADM trough concentrations were above the upper limit of the predefined ADM target range of 9 mg/L. Proportions of virtual patients within the extrapolated target exposure range from adults including a safety-margin, i.e., 4–9 mg/L, were assessed and compared to label dosing, stratified by body weight. In children and adolescents with JIA weighing 30 to 50 kg both, dose interval extension to 21 days and dose reduction to 30 mg EOW increased proportion of patients within predefined target range from 17 - 29% (label dose regimen) to 34–43% or 28–43%, respectively. TDM-guided tapering for patients with trough concentrations > 9 mg/L further increased proportion with target exposure to 56–63% while keeping the proportion of patients with trough concentrations < 2 mg/L similar to label dosing (≤ 2%). This simulation study suggests that ADM tapering, in children with JIA who reached remission, may be applicable. Appropriate ADM dose reduction or dose interval extension, especially when supported by TDM, could help to reduce treatment-related and socioeconomic burden, while minimize risk of underexposure. Provided simulation framework can be validated and further fine-tuned once paediatric exposure-response data and target ranges have been established.