A Study to Evaluate the Efficacy and Safety of Bimekizumab in Adult Study Participants With Active Psoriatic Arthritis

Inclusion Criteria: * Study participants must have a documented diagnosis of adult-onset PsA classified by and that meets the CASPAR classification criteria for at least 6 months prior to Screening with active PsA (despite previous csDMARD or apremilast therapy) and must have at Baseline tender joint count (TJC) ≥3 out of 68 joints and swollen joint count (SJC) ≥3 out of 66 joints (dactylitis of a digit counts as 1 joint each). * Study participant must have at least 1 active psoriatic lesion(s) and/or a documented history of chronic plaque-type psoriasis (PSO). * Study participants may currently be on conventional synthetic disease-modifying antirheumatic drug (csDMARD) therapy and must have previously been treated with at least 1 csDMARD (methotrexate (MTX), leflunomide (LEF), sulfasalazine (SSZ)). Study participants must have had an inadequate response to therapy or discontinued due to intolerance. (Inadequate response is determined by the Investigator and is defined as not achieving the minimal response after 12 weeks of therapy.) * Study participants can either be biological disease-modifying antirheumatic drug (bDMARD)-naïve or have received not more than 1 prior tumor necrosis factor alpha (TNFα) inhibitor. Study participants who have been on a TNFα inhibitor previously must not have discontinued the TNFα inhibitor due to financial or health insurance reasons and must have either: * experienced an inadequate response to previous treatment given at an approved dose for …