Therapeutic Drug Monitoring of Guselkumab in Psoriasis Patients

Study Overview
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Brief Summary
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Biologic such as guselkumab are currently the most effective treatment option for patients with moderate to severe psoriasis. But they are costly for healthcare systems and still described according to a 'one dose fits all' dosing regimen, leading to potential over- and undertreatment. In this study we aim to investigate the predictive value of early serum trough levels of guselkumab and determine the therapeutic window of guselkumab in psoriasis patients.

Detailed Description
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Patients will be included after signing informed consent. After inclusion, patients will continue on standard dosing schedule of guselkumab (i.e. one loading dose (100 mg) at week 0 and week 4 and followed by subcutaenously injections every 8 weeks). During each study visit blood will be taken in order to quantify Ctroughs and/or anti-drug antibodies towards guselkumab. In addition, Psoriasis Area and Severity Index (PASI) and Investigator's Global Assessment (IGA) score will be evaluated by a physician. Patients complete the Dermatology Life Quality Index (DLQI) and European quality of life EQ-5D instrument at each visit.

Official Title
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Evaluation of the Preditive Value of Early Serum Trough Concentrations and Anti-drug Antibodies of Guselkumab and the Development of the Concentration-response Curve of Guselkumab for Psoriasis Patients.

Conditions
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Psoriasis Vulgaris

Intervention / Treatment
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* Procedure: Venapuncture
* Other: Patient questionnaires


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Participants must have a clinical or histological diagnosis of chronic plaque-type psoriasis Participants must sign an ICF indicating that he or she understands the purpose of, and procedures required for, the study and is willing to participate in the study Exclusion Criteria: Participants who have currently a predominant nonplaque form of psoriasis Participants who are pregnant, nursing or planning a pregnancy Participants who are unable or unwilling to undergo multiple venapunctures Participants who are treated according to a different dosing schedule than standard dosing of guselkumab

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Interventional Model Description: A prospective, open label, non-randomized study
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Standard of case - guselkumab<br>Patients will continue to receive guselkumab according to the standard dosing schedule; subcutaneous injection of 100 mg at weeks 0 and 4 and then every 8 weeks | Procedure: Venapuncture<br>* Blood samples will be collected to determine the serum trough levels and anti-drug antibodies of guselkumab.<br>Other: Patient questionnaires<br>* The study participant will complete the dermatology quality of life index (DLQI) and EQ-5D-5L questionnaire at each study visit<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Predictive value of early serum trough concentrations of guselkumab | Prediction of the clinical response (PASI) at week 12 and/or week 24 based on serum trough concentrations of guselkumab measurements taken from week 0, 1, 2, 3, and/or 4. | Week 0 until week 24 of treatment | 
| Predictive value of early anti-drug antibodies of guselkumab | Prediction of the clinical response (PASI) at week 12 and/or week 24 based on anti-drug antibodies of guselkumab measurements taken from week 0, 1, 2, 3, and/or 4. | Week 0 until week 24 of treatment | 
| Development of the therapeutic window of guselkumab in psoriasis | Defining a therapeutic window for guselkumab based on serum trough concentrations corresponding with adequate clinical response | Week 0 until week 52 of treatment | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| DLQI | The DLQI (Dermatology Life Quality Index) (range 0-30) is a dermatology specific quality of life (QoL) instrument designed to assess the impact of the disease on participant's QoL. It is a ten item questionnaire that, in addition to evaluated overall QoL, can be used to assess six different aspects that may affect QoL: 1) symptoms and feelings, 2) daily activities, 3) leasure, 4) work or school performances, 5) personal relationships, and 6) treatment. The scoring of each question is as follows: Very much - scored 3; A lot - scored 2; A little - scored 1; Not at all - scored 0; Not relevant - scored 0; Question 7, 'prevented work or studying' - scored 3. The DLQI is calculated by summing the score of each question resulting in a maximum of 30 and a minimum of 0. The higher the score, the more quality of life is impaired. | Week 0 until week 52 of treatment | 
| EQ-5D-5L | The EQ-5D-5L comprises five dimensions: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. Each dimension has 5 levels: no problems, slight problems, moderate problems, severe problems and extreme problems. The patient is asked to indicate his/her health state by ticking the box next to the most appropriate statement in each of the five dimensions. This decision results in a 1-digit number that expresses the level selected for that dimension. The digits for the five dimensions can be combined into a 5-digit number that describes the patient's health state. | Week 0 until week 52 of treatment | 
| EQ VAS | The EQ VAS (Visual Analogue Scale) (range 0-10) records the patient's self-rated health on a vertical visual analogue scale, where the endpoints are labelled 'The best health you can imagine' and 'The worst health you can imagine'. The VAS can be used as a quantitative measure of health outcome that reflect the patient's own judgement. | Week 0 until week 52 of treatment | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Therapeutic drug monitoring, Psoriasis, Guselkumab