Study to Evaluate the Efficacy and Safety of Filgotinib in Participants With Active Psoriatic Arthritis Who Have an Inadequate Response or Are Intolerant to Biologic DMARD Therapy

Key Inclusion Criteria:

Male or female participants who are 18-75 years of age (19-75 years of age at sites in Republic of Korea, 20-75 years of age at sites in Japan and Taiwan), on the day of signing initial informed consent
Meet Classification Criteria for Psoriatic Arthritis (CASPAR)
Have a history consistent with Psoriatic Arthritis (PsA) ≥ 6 months at Screening
Have active PsA defined as ≥ 3 swollen joints (from a 66 swollen joint count [SJC]) and ≥ 3 tender joints (from a 68 tender joint count [TJC]) at Screening and Day 1; these may or may not be the same joints at Screening and Day 1

Must have a documented history or active signs of at least one of the following at Screening

Plaque psoriasis
Nail changes attributed to psoriasis
Have had inadequate response (lack of efficacy after ≥ 12 week duration of therapy) or intolerance to at least one and not more than 3 biologic DMARDs (bioDMARD) administered for the treatment of PsA or psoriasis, as per local guidelines / standard of care
Prior to the first dose of study drug on Day 1, treatment with bioDMARD(s) should have been discontinued

Key Exclusion Criteria:

Prior exposure to a janus kinase (JAK) inhibitor > 2 doses
Any active / recent infection
Any chronic and / or uncontrolled medical condition that would put the individual at increased risk during study participation or circumstances which may make a individual unlikely or unable to complete or comply with study procedures and requirements, per investigator judgement
Any moderately to severely active musculoskeletal or skin disorder other than PsA or plaque psoriasis that would interfere with assessment of study parameters, as per judgement of investigator

NOTE: Prior history of reactive arthritis or axial spondyloarthritis is permitted if there is documentation of change in diagnosis to PsA or additional diagnosis of PsA

Any history of an inflammatory arthropathy with onset before age of 16 years old
Active autoimmune disease that would interfere with assessment of study parameters or increase risk to the individual by participating in the study, (e.g. uveitis, inflammatory bowel disease, uncontrolled thyroiditis, systemic vasculitis, transverse myelitis), per judgement of investigator
Pregnancy or nursing females
Active drug or alcohol abuse, as per judgement of investigator

Note: Other protocol defined Inclusion/Exclusion criteria may apply.