A 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