PsA is a chronic, immune-mediated inflammatory disease characterized by peripheral joint inflammation, enthesitis, dactylitis, axial disease, and the skin lesions associated with psoriasis. Guselkumab is a fully human monoclonal antibody (mAb) that binds to p19 protein subunit of interleukin (IL)-23 and blocks the binding of extracellular IL-23 to the cell surface IL-23 receptor, inhibiting IL-23 specific intracellular signaling, subsequent activation, and cytokine production. The primary hypothesis of this study is that guselkumab is superior to placebo as assessed by the proportion of participants who had an inadequate response (IR) and/or intolerance to one prior anti-tumor necrosis factor (anti-TNF) achieving an American College of Rheumatology 20 (ACR 20) response at Week 24. This study will consist of a screening phase (up to 6 weeks), blinded treatment phase (approximately up to 2 years), which includes a placebo-controlled period from Week 0 to Week 24, and an active-controlled treatment phase from Week 24 to Week 100, and safety follow-up phase (Week 112). Safety assessments will include physical examinations, vital signs, height, weight, electrocardiograms, and clinical safety laboratory assessments. The total duration of the study will be up to 118 weeks.

PsA is a chronic, immune-mediated inflammatory disease characterized by peripheral joint inflammation, enthesitis, dactylitis, axial disease, and the skin lesions associated with psoriasis. Guselkumab is a fully human monoclonal antibody (mAb) that binds to p19 protein subunit of interleukin (IL)-23 and blocks the binding of extracellular IL-23 to the cell surface IL-23 receptor, inhibiting IL-23 specific intracellular signaling, subsequent activation, and cytokine production. The primary hypothesis of this study is that guselkumab is superior to placebo as assessed by the proportion of participants who had an inadequate response (IR) and/or intolerance to one prior anti-tumor necrosis factor (anti-TNF) achieving an American College of Rheumatology 20 (ACR 20) response at Week 24. This study will consist of a screening phase (up to 6 weeks), blinded treatment phase (approximately up to 2 years), which includes a placebo-controlled period from Week 0 to Week 24, and an active-controlled treatment phase from Week 24 to Week 100, and safety follow-up phase (Week 112). Safety assessments will include physical examinations, vital signs, height, weight, electrocardiograms, and clinical safety laboratory assessments. The total duration of the study will be up to 118 weeks.