A Study of Guselkumab in Participants With Active Psoriatic Arthritis and an Inadequate Response to Anti-Tumor Necrosis Factor Alpha (Anti-TNF Alpha) Therapy

The purpose of this study is to evaluate guselkumab efficacy versus placebo in participants with active psoriatic arthritis (PsA) and an inadequate response to Anti-Tumor Necrosis Factor Alpha (TNF-alpha) therapy by assessing the reduction in signs and symptoms of joint disease.

Psoriatic arthritis is a multi-faceted disease that impacts the joints, soft tissues, and skin, all of which not only results in functional disability and impaired quality of life, but participants with this disease also have increased mortality. Guselkumab is a monoclonal antibody that binds to human interleukin 23 (IL-23) and inhibits IL-23 specific intracellular signaling and subsequent activation and cytokine production. Investigation of guselkumab in this Phase 3b PsA clinical study is supported by the favorable efficacy and safety results from Phase 2 study of guselkumab in PsA and Phase 2 and Phase 3 studies in psoriasis including the subset of participants with PsA. The primary hypothesis is that guselkumab 100 milligram (mg) at Weeks 0, 4, and every 8 weeks (q8w) thereafter is superior to placebo which will be assessed by the proportion of participants achieving an American College of Rheumatology (ACR 20) response at Week 24. The study includes 2 periods: A 24-week double-blind, placebo-controlled period for the primary analysis of the efficacy and safety of guselkumab, compared with placebo and a 32-week active-treatment and safety follow-up period for additional analysis of the efficacy and safety of guselkumab. Safety will be monitored throughout the study (Up to Week 56).

Eligibility Criteria:
Inclusion Criteria:

* Have a diagnosis of psoriatic arthritis (PsA) for at least 6 months before the first administration of study intervention and meet classification criteria for Psoriatic Arthritis (CASPAR) at screening
* Have active PsA as defined by at least 3 swollen joints and at least 3 tender joints at screening and at baseline
* Have at least 1 of the PsA subsets: distal interphalangeal joint involvement, polyarticular arthritis with absence of rheumatoid nodules, arthritis mutilans, asymmetric peripheral arthritis, or spondylitis with peripheral arthritis
* Have an inadequate response to anti-TNF alpha therapy, defined as presence of active PsA despite previous treatment with either 1 or 2 anti-TNF alpha agents and either of the following: a) Lack of benefit of an anti-TNF alpha therapy, as documented in the participant history by the treating physician, after at least 12 weeks of etanercept, adalimumab, golimumab, or certolizumab pegol therapy (or biosimilars) and/or at least a 14-week dosage regimen (i.e., at least 4 doses) of infliximab (or biosimilars). Documented lack of benefit may include inadequate improvement in joint counts, skin response, physical function, or disease activity, b) Intolerance to an anti-TNF alpha therapy, as documented in the patient history by the treating physician, to etanercept, adalimumab, golimumab, certolizumab pegol, or infliximab (or biosimilars, if available)
* Be willing to refrain from the use of complementary therapies for PsA or psoriasis including ayurvedic medicine, traditional Taiwanese, Korean, or Chinese medications and acupuncture within 2 weeks before the first study intervention administration and through Week 48

Exclusion Criteria:

* Has other inflammatory diseases that might confound the evaluations of benefit of guselkumab therapy, including but not limited to rheumatoid arthritis (RA), axial spondyloarthritis (this does not include a primary diagnosis of PsA with spondylitis), systemic lupus erythematosus, or Lyme disease
* Has ever received more than 2 different anti-TNF alpha agents
* Has previously received any biologic treatment (other than anti-TNF Alpha agents), including, but not limited to ustekinumab, abatacept, secukinumab, tildrakizumab, ixekizumab, brodalumab, risankizumab, or other investigative biologic treatment
* Has previously received tofacitinib, baricitinib, filgotinib, peficitinib (ASP015K), decernotinib (VX 509), or any other a Janus kinase (JAK) inhibitor
* Has previously received any systemic immunosuppressants (for example, azathioprine, cyclosporine, 6 thioguanine, mercaptopurine, mycophenolate mofetil, hydroxyurea, tacrolimus) within 4 weeks of the first administration of study intervention