therapeutic drug monitoring: towards tailored dosing of adalimumab in rheumatoid arthritis

Treatment with biologicals is based on the principle of *one size fits all*. In
the dosing scheme, patients characteristics or pharmacokinetic aspects are not
taken into account. In addition, when a patient responds well to the drug, the
question whether the dose can be de-escalated or the drug can be discontinued,
remains unanswered. Based on literature, dose de-escalation seems to be safe
with regard to disease activity and might be beneficial in lowering the risk of
adverse events. An important additional aspect is the large amount of costs
that can be saved when the same response rates are achieved with less
medication.

To examine disease activity in patients with high serum adalimumab
concentration who are randomly assigned to continuation of the regular dose or
to dose interval prolongation and to examine the cost-effectiveness of this
therapeutic drug monitoring strategy.

Open randomised controlled study of therapeutic drug monitoring in 112 RA
patients treated with adalimumab.

Patients with high adalimumab concentrations will be randomly assigned for
continuation of adalimumab every other week or prolongation of the dosage
interval to once every 3 weeks. Patients assigned to continuation of adalimumab
treatment prolong the dosage interval to once every 3 weeks for an additional 6
months after 6 months of continuation of the original dosage. The endpoint of
the study for patients assigned to prolongation of the dosage initially, will
be 6 months after inclusion.

We hypothesize that in patients with high adalimumab concentrations and dose
interval prolongation disease activity remains stable, however, an increased
disease activity risk can not be excluded.