A Study to Determine the Efficacy and Safety of Deucravacitinib Compared With Placebo in Participants With Active Psoriatic Arthritis (PsA) Who Are Naïve to Biologic Disease Modifying Anti-rheumatic Drugs or Had Previously Received TNFα Inhibitor Treatment

Inclusion Criteria:

• Diagnosed to have psoriatic arthritis (PsA) of at least 3 months duration atScreening

• Meets the Classification Criteria for Psoriatic Arthritis (CASPAR) criteria atScreening

• Active plaque psoriatic skin lesion(s) or documented medical history of plaquepsoriasis (PsO) at Screening

• Active arthritis as shown by ≥ 3 swollen joints and ≥ 3 tender joints at Screeningand Day 1

• Participant has high sensitivity C-reactive protein (hsCRP) ≥ 3 mg/L at Screening

• Must have completed the week 52 treatment for the optional open-label long-termextension period

Exclusion Criteria:

• Nonplaque psoriasis at Screening or Day 1

• Other autoimmune condition such as systemic lupus erythematous, mixed connectivetissue disease, multiple sclerosis, or vasculitis

• History of or current inflammatory joint disease other than PsA (e.g., gout,reactive arthritis, rheumatoid arthritis, ankylosing spondylitis, Lyme disease)

• Active fibromyalgia

• Received an approved or investigational biologic therapy for the treatment of PsA orPsO

Other protocol-defined inclusion/exclusion criteria apply