A Study to Evaluate the Efficacy and Safety of Bimekizumab in the Treatment of Subjects With Active Psoriatic Arthritis

Inclusion Criteria

• Subject is male or female at least 18 years of age
• Female subjects must be postmenopausal, permanently sterilized or willing to use a highly effective method of contraception
• Documented diagnosis of adult-onset Psoriatic Arthritis (PsA) meeting the Classification Criteria for Psoriatic Arthritis (CASPAR) for at least 6 months prior to Screening with active PsA and must have at Baseline tender joint count (TJC) >=3 out of 68 and swollen joint count (SJC) >=3 out of 66
• Subject must be negative for rheumatoid factor and anti-cyclic citrullinated peptide (CCP) antibodies
• Subject must have at least 1 active psoriatic lesion(s) and/or a documented history of psoriasis (PSO)
• Subject has a history of inadequate response (lack of efficacy after at least 3 months of therapy at an approved dose) or intolerance to treatment with 1 or 2 tumor necrosis factor alpha (TNF(α)) inhibitors for either PsA or PSO
• Subjects currently taking NSAIDs, cyclooxygenase 2 (COX-2) inhibitors, analgesics (including mild opioids), corticosteroids, methotrexate (MTX), leflunomide (LEF), sulfasalazine (SSZ), hydroxychloroquine (HCQ) AND/OR apremilast can be allowed if they fulfill specific requirements prior to study entry

Exclusion Criteria

• Female subjects who are breastfeeding, pregnant, or plan to become pregnant during the study
• Subjects with current or prior exposure to any biologics except tumor necrosis factor (TNF) inhibitors for the treatment of PsA or PSO
• Subject has an active infection or a history of recent serious infections
• 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 a diagnosis of inflammatory conditions other than PSO or PsA. Subjects with a diagnosis of Crohn's disease, ulcerative colitis, or other inflammatory bowel disease (IBD) are allowed as long as they have no active symptomatic disease at Screening or Baseline
• Subject had acute anterior uveitis within 6 weeks of Baseline
• 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
• Subject has a form of PSO other than chronic plaque-type (eg, pustular, erythrodermic and guttate PSO, or drug-induced PSO)
• Presence of active suicidal ideation, or moderately severe major depression or severe major depression
• Subject has a history of chronic alcohol or drug abuse within 6 months prior to Screening