A Study of Guselkumab Administered Subcutaneously in Bio-naive Participants With Active Psoriatic Arthritis Axial Disease

Open to people ages 18 years and up

• Have a diagnosis of psoriatic arthritis (PsA) for at least 6 months prior to the first administration of study intervention and meet classification criteria for psoriatic arthritis (CASPAR) criteria at screening
• Have active PsA as defined by: a) at least 3 swollen joints and at least 3 tender joints at screening and at baseline and b) C-reactive protein (CRP) greater than or equal to (>=) 0.3 milligram/deciliter (mg/dL) at screening from the central laboratory, and despite previous non-biologic disease modifying antirheumatic drug (DMARD), apremilast, and/or nonsteroidal anti-inflammatory drug (NSAID) therapy
• Have magnetic resonance imaging (MRI)-confirmed PsA axial disease (positive MRI spine and/or sacroiliac [SI] joints, shown by a Spondyloarthritis Research Consortium of Canada [SPARCC] score of >= 3 in either the spine or the sacroiliac joints)
• Have a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score of at least 4, and have a spinal pain score (on a visual analog scale [VAS]) of at least 4
• Have active plaque psoriasis, with at least 1 psoriatic plaque of >= 2 centimeter (cm) diameter and/or nail changes consistent with psoriasis, or documented history of plaque psoriasis

• Has known allergies, hypersensitivity, or intolerance to guselkumab or its excipients
• Has other inflammatory diseases that might confound the evaluations of benefit of guselkumab therapy, including but not limited to rheumatoid arthritis (RA), ankylosing spondylitis (AS)/non-radiographic-axial spondyloarthritis (this does not include a primary diagnosis of PsA with spondylitis), systemic lupus erythematosus, or Lyme disease
• Has previously received any biologic treatment
• Has ever received a Janus kinase (JAK) inhibitor including but not limited to tofacitinib, baricitinib, filgotinib, peficitinib, decernotinib, upadacitinib or any other investigational JAK inhibitor
• Has received any systemic immunosuppressants (example, azathioprine, cyclosporine, 6 thioguanine, mercaptopurine, mycophenolate mofetil, hydroxyurea, tacrolimus) within 4 weeks of the first administration of study intervention