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

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 <12 with at least one of the following:

• >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 mayalternatively have a diagnosis of moderate to severe mixed guttate/plaque PSO with >50 % to <80 % guttate lesions for ≥3 months, and must meet the same criteria listedabove

• Study participant must be a candidate for systemic psoriasis therapy and/orphototherapy and/or photochemotherapy

Exclusion Criteria:

• Study participant previously participated in this study or has previously beentreated with certolizumab pegol (CZP)

• Study participant has generalized pustular or erythrodermic psoriasis (PSO)

• Study participant has guttate PSO without plaque PSO

• Study participant has had a primary failure to an anti-tumor necrosis factor agent

• Study participant has had prior exposure 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 hadsuicidal 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 theColumbia Suicide Severity Rating Scale (CSSRS) at Screening