A Study to Evaluate the Pharmacokinetics, Safety, and Effectiveness of Certolizumab Pegol in Children With Moderate to Severe Chronic Plaque Psoriasis

The purpose of the study is to evaluate the pharmacokinetic (PK) of certolizumab pegol (CZP) in study participants aged 6 to 17 years with moderate to severe chronic plaque psoriasis (PSO) in order to support extrapolation of efficacy.

Inclusion Criteria: * Study participant must have a diagnosis of moderate to severe plaque psoriasis (PSO) for ≥3 months and: 1. Body Surface Area (BSA) affected by psoriasis ≥10 % 2. Physician's Global Assessment (PGA) score ≥3 (on a scale from 0 to 4) 3. Psoriasis Area and Severity Index (PASI) score is ≥12 or 4. PASI score is ≥10 and \Clinically relevant facial or scalp involvement * \>Clinically relevant genital involvement * \>Clinically relevant palm and sole involvement * \>Clinically relevant axillary involvement Study participants aged ≥12 years may alternatively have a diagnosis of moderate to severe mixed guttate/plaque PSO with \>50 % to \2 biologic therapies * Study participant has a history of severe major depression or suicide attempt (including an actual attempt, interrupted attempt, or aborted attempt), or has had suicidal ideation in the past 6 months as indicated by a positive response ("Yes") to either Question 4 or Question 5 of the "Screening/Baseline" version of the Columbia Suicide Severity Rating Scale (CSSRS) at Screening