Rationale: Biologics are very effective treatments for psoriasis. Research indicated that the dose of TNFα-blocking biologics can be reduced in a proportion of patients. Safety profiles can improve and costs can be reduced if the reduction of the dose is successful. Recently, the newest generation of biologics entered the market: interleukin (IL) 17 and IL23 inhibitors. It is not yet known whether dose reduction of these agents is possible, and to what extent they can be reduced. The timely investigation of the possibilities for dose reduction of new biologics is therefore important.~Objectives: The primary goal is to investigate whether controlled dose reduction of IL17 or IL23 inhibiting biologics is not inferior compared to usual care. This is measured by comparing the proportion of long-term disease flares between the two groups (dose reduction group versus usual care group). Secondary goals are: determining the proportion of patients with successful dose reduction, clinical effectiveness measured with the Psoriasis Area and Severity score (PASI) score, Dermatology Life Quality Index (DLQI) scores, predictors for successful dose reduction, safety, and cost-effectiveness of dose reduction. Pharmacokinetic (PK) analysis will be performed for modeling.~Study design: a multicenter, practice-oriented, pragmatic, randomized, controlled, non-inferiority study.~Study population: Patients treated with the newest generation of biologics (IL17 or IL23 inhibitors), with long-term stable low disease activity at a normal dose. A total of 244 patients will be randomized (2:1) to dose reduction or continuation of usual care.~Intervention: Dose reduction by interval prolongation in 2 steps to a maximum decrease of 50% of the original dose when disease activity (PASI) and quality of life index (DLQI) remain low.
The main objective of this study is to investigate whether controlled dose reduction of IL17 or IL23 inhibiting biologics is not inferior compared to usual care in psoriasis patients. Therefore, a pragmatic, multicentre, randomized, controlled, non-inferiority study will be carried out.