Study to Evaluate the Pharmacokinetics (PK), Pharmacodynamics (PD), and Safety of Bimekizumab in Patients With Chronic Plaque Psoriasis

Inclusion Criteria:

- Male or female at least 18 years of age and less than or equal to 70

- Chronic plaque psoriasis for at least 6 months prior to Screening

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

- Candidates for systemic psoriasis therapy and/or phototherapy and/or chemophototherapy

- Female subjects must be postmenopausal, permanently sterilized or, if of childbearing
potential, must be willing to use a highly effective method of contraception up till
20 weeks after last administration of study drug, and have a negative pregnancy test
at Visit 1 (Screening) and immediately prior to first dose

- Male subjects with a partner of childbearing potential must be willing to use a condom
when sexually active, up till 20 weeks after the last administration of study
medication (anticipated 5 half-lives)

Exclusion Criteria:

- Subjects previously participating in a bimekizumab study

- Subjects with erythrodermic, guttate, pustular form of psoriasis, or drug-induced
psoriasis

- History of chronic or recurrent infections, or a serious or life-threatening infection
within the 6 months prior to the Baseline Visit (including herpes zoster)

- High risk of infection in the Investigator's opinion

- Current sign or symptom that may indicate an active infection

- Concurrent acute or chronic viral hepatitis B or C or human immunodeficiency virus
(HIV) infection

- Live (includes attenuated) vaccination within the 8 weeks prior to Baseline

- Subjects with concurrent malignancy or history of malignancy during the past 5 years
(except for specific malignant condition as defined in the protocol)

- Primary immunosuppressive conditions

- TB infection, high risk of acquiring TB infection, latent TB infection (LTBI), or
current or history of NTMB infection

- Laboratory abnormalities, as defined in the study protocol

- Any condition which, in the Investigator's judgement, would make the subject
unsuitable for inclusion in the study

- Exposure to more than 1 biological response modifier (limited to anti-TNF or
IL-12/-23) or any biologic response modifier during the three months prior to the
Baseline Visit

- Subjects have received previous treatment with any anti-IL-17 therapy for the
treatment of psoriasis or psoriatic arthritis

- Subjects with a diagnosis of inflammatory conditions other than psoriasis or psoriatic
arthritis, including but not limited to rheumatoid arthritis, sarcoidosis, or systemic
lupus erythematosus. Subjects with a diagnosis of Crohn's disease or ulcerative
colitis are allowed as long as they have no active symptomatic disease at Screening or
Baseline

- Subjects taking psoriatic arthritis medications other than nonsteroidal
anti-inflammatory drugs (NSAIDs) or analgesics