A Study to Evaluate the Efficacy and Safety of Bimekizumab Compared to an Active Comparator in Adult Subjects With Moderate to Severe Chronic Plaque Psoriasis

This is a study to compare the efficacy of bimekizumab versus secukinumab in subjects with moderate to severe chronic plaque psoriasis (PSO).

The study consists of a 48-week double-blind Treatment Period, an optional 96-week open-label extension (OLE) Period and an optional 48-week OLE2 Period for eligible subjects in the USA and Canada.

Eligibility Criteria:
Inclusion Criteria:

Double-blind Treatment Period

* Male or female at least 18 years of age
* Subject must have had chronic plaque psoriasis (PSO) for at least 6 months prior to the Screening visit
* Subject must have 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 must be a candidate for systemic PSO therapy and/or phototherapy
* Subject must be considered, in the opinion of the Investigator, to be a suitable candidate for treatment with secukinumab per regional labeling and has no contraindications to receive secukinumab as per the local label
* Female subject of childbearing potential must be willing to use highly effective method of contraception

Open-label extension (OLE) Period

* Completed the double-blind Treatment Period without meeting any withdrawal criteria
* All Week 48 visit assessments completed
* Compliant with ongoing clinical study requirements
* Signed a separate OLE Period Informed Consent Form (ICF)
* Female subject of childbearing potential must be willing to use highly effective method of contraception

OLE2 Period (USA and Canada)

* Completed the OLE Period without meeting any withdrawal criteria
* Compliant with ongoing clinical study requirements
* Female subject of childbearing potential must be willing to use highly effective method of contraception
* Subjects with a diagnosis of Crohn's disease or ulcerative colitis are allowed as long as they have no active symptomatic disease (US only)
* Signed a separate OLE2 Period ICF

Exclusion Criteria:

Double-blind Treatment Period

* Subject has an active infection (except common cold), a 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 severe 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

OLE2 Period (USA and Canada)

* Subject has developed any medical or psychiatric condition, which, in the Investigator's judgment, would make the subject unsuitable for inclusion in OLE2 Period
* Subject had a positive or indeterminate interferon-gamma release assay (IGRA) in the OLE study to Week 144, unless appropriately evaluated and treated
* Presence of active suicidal ideation or severe depression
* Subject has developed any active malignancy or history of malignancy prior to the OLE2 Screening Visit EXCEPT treated and considered cured cutaneous squamous or basal cell carcinoma, or in situ cervical cancer