In this study we investigate whether dose reduction of adalimumab in patients with supratherapeutic adalimumab Ctrough levels is non-inferior to standard dosing of adalimumab.~Before randomization, 3 subsequent evaluations of adalimumab Ctroughs will be executed. Patients will be included after signing informed consent and randomized if 2/3 subsequent measurements during screening show supratherapeutic Ctrough levels. Time point of randomization is considered baseline (week 0). PASI calculation will be performed by a blinded and independent physician.~In the concentration based arm, dosing frequency will be lowered to 40 mg every 3 weeks (33% reduction). In case of persistent supratherapeutic Ctroughs, a 50% dose reduction will be applied from week 12 onwards. In the standard based arm, patients will continue on standard dosing schedule of 40 mg every other week.~During each study visit PASI and IGA score will be evaluated by an independent and blinded physician and adverse events, and concomitant medications will be evaluated by a member of the study team. Ctrough is quantified at each visit; and anti-drug antibodies concentrations only if subtherapeutic concentrations are observed. Patients complete the Dermatology Life Quality Index (DLQI) and EuroQol-5D-5L instrument at each visit.~In addition, in a subset of patients in each treatment arm, additional sampling will be collected by dried blood spot sampling in order to build a PK(PD) model for adalimumab,
Recently, the optimal therapeutic serum trough level range of adalimumab was defined between 3,5 and 7,0 µg/ml in patients with plaque type psoriasis. An adalimumab serum through level above this therapeutic range did not add to clinical response. Based on this therapeutic window, the introduction of dose adjustments based on serum trough levels (therapeutic drug monitoring) will be further validated in a prospective controlled trial. Here, we aim to determine whether, in patients with a good clinical response and supratherapeutic adalimumab STLs, dose reduction based on therapeutic drug monitoring (TDM) is able to maintain the initial clinical outcome.