['psoriatic arthritis']
['filgotinib', 'placebo oral tablet']

        Key Inclusion Criteria:

          -  Male or female subjects who are ≥18 years of age, on the day of signing informed
             consent.

          -  Diagnosis of psoriatic arthritis meeting Classification Criteria for Psoriatic
             Arthritis (CASPAR)

          -  Have active psoriatic arthritis defined as ≥5 swollen joints (from a 66 swollen joint
             count [SJC]) and ≥5 tender joints (from a 68 tender joint count [TJC]) at Screening
             and Baseline (measurable dactylitis of a digit counts as a single swollen joint and if
             tender, then also a single tender joint).

          -  Have had a history of documented plaque psoriasis or currently active plaque psoriasis

          -  If using cDMARD therapy, subjects must have been on it for 12 weeks prior to
             screening, with a stable dose (including stable route of administration) for at least
             4 weeks prior to baseline.

          -  If using non-drug therapies (including physical therapies), thse should be kept sable
             during screening

          -  Male and female subjects of childbearing potential who engage in heterosexual
             intercourse must agree to use highly effective methods of contraception as described
             in the protocol

        Key Exclusion Criteria:

          -  Use of JAK inhibitors, investigational or approved, at any time, including filgotinib;

          -  Prior use of more than one TNF inhibitor, at any time.

          -  Use of oral steroids at a dose >10 mg/day of prednisone or prednisone equivalent or at
             a dose that hasn't been stable for at least 4 weeks prior to Baseline;

          -  Any therapy by intra-articular injections (e.g. corticosteroid, hyaluronate) within 4
             weeks prior to screening;

          -  Use of more than 1 NSAID or cyclooxygenase-2 (COX-2) inhibitor.

          -  Have undergone surgical treatment for psoriatic arthritis including synovectomy and
             arthroplasty in more than 3 joints and/or within the last 12 weeks prior to screening

          -  Presence of very poor functional status or unable to perform self-care.

          -  Administration of a live or attenuated vaccine within 12 weeks prior to baseline
      