A Study With a Initial Treatment Period Followed by a Randomized-withdrawal Period to Evaluate the Efficacy and Safety of Bimekizumab in Adult Subjects With Moderate to Severe Chronic Plaque Psoriasis

Inclusion Criteria:

- Must be at least 18 years of age

- Chronic plaque psoriasis (PSO) for at least 6 months prior to the Screening Visit

- Psoriasis Area Severity Index (PASI) >=12 and body surface area (BSA) affected by PSO
>=10% and Investigator's Global Assessment (IGA) score >=3 on a 5-point scale

- Subject is a candidate for systemic PSO therapy and/or phototherapy

- Female subject of child bearing potential must be willing to use highly effective
method of contraception

Exclusion Criteria:

- Subject has an active infection (except common cold), a recent serious infection, or a
history of opportunistic, recurrent, or chronic infections

- Subject has concurrent acute or chronic viral hepatitis B or C or human
immunodeficiency virus (HIV) infection

- Subject has known tuberculosis (TB) infection, is at high risk of acquiring TB
infection, or has current or history of nontuberculous mycobacterium (NTMB) infection

- Subject has any other condition, including medical or psychiatric, which, in the
Investigator's judgment, would make the subject unsuitable for inclusion in the study

- Presence of active suicidal ideation or positive suicide behavior

- Presence of moderately severe major depression or severe major depression

- Subject has any active malignancy or history of malignancy within 5 years prior to the
Screening Visit EXCEPT treated and considered cured cutaneous squamous or basal cell
carcinoma, or in situ cervical cancer