Proactive TDM Versus Standard Use of Biologics in Psoriasis

Rationale: Biologics are effective agents for the treatment of psoriasis. The newest generation of biologics block interleukin 17 and 23. Physicians always prescribe these drugs in a fixed dose, but this may lead to under- and overdosing in some patients. Underdosing may lead to inadequate response or loss of response over time. Overdosage, on the other hand, can lead to higher risk of side effects and higher costs for the healthcare system. In daily clinical practice, physicians often tackle this real-world issue by blind trial- and- error dose modifications or switching to another biologic. In this study, we want to rationalize these dose modifications and optimize dosing based on the drug concentrations, measured in the blood of the patient (i.e. therapeutic drug monitoring). Objectives: The primary goal is to assess if proactive TDM is non-inferior compared to standard of care with respect to sustained disease control, defined as an absolute PASI ≤ 2 OR a delta PASI from baseline ≥ 50% during at least 80% of all 3-monthly study visits over a period of 18 months, in patients with moderate to severe psoriasis treated with novel biologics (secukinumab, ixekizumab or guselkumab). Secondary goals are: To compare proactive TDM to standard of care with respect to disease activity, quality of life, treatment satisfaction and costs of treatment (cost-effectiveness) To identify baseline predictors for sustained disease control. To evaluate the cost-effectiveness of proactive TDM To evaluate the safety of proactive TDM. Study design: A multicentre, pragmatic, randomised, controlled, non-inferiority trial. Study population: Patients with moderate-to-severe psoriasis, treated with secukinumab or ixekizumab (IL-17 inhibitors) or guselkumab (IL-23 inhibitor) in daily clinical practice for at least 6 months on standard dosing (maintenance phase). A total of 210 patients will be randomized (1:1) to the intervention group (TDM based dosing) or continuation of usual care. Intervention: Stepwise treatment modifications based on drug levels: if the drug level is below/above the target, the dose of the biologic will be increased/decreased by stepwise interval shortening/lengthening - first modified by 33% and then 50% increase or decrease. If the target is still not reached at the next study visit, the dosing interval will be shortened or prolonged with one additional week at each additional visit until the target is reached. In case the dosing regimen shifts from dose increase to dose decrease or vice versa, the dosing interval will be shortened or prolonged with one additional week at each additional visit until the target is reached.