Psoriatic arthritis (PsA) is a chronic inflammatory disease that affects the joints and skin in people who have psoriasis (PsO).
The main aim of the study is to know how well zasocitinib (TAK-279) works in participants with active PsA based on their previous experience with specific treatments.
The participants will be treated with either zasocitinib, or placebo. Participants will be in the study for up to 60 weeks.
The participant is aged 18 years or older at the time of signing the informed consent form (ICF).
The participant has a diagnosis of PsA.
The participant must have signs and symptoms of PsA for at least 3 months prior to screening.
The participant meets the Classification Criteria for Psoriatic Arthritis (CASPAR criteria).
The participant has other disease(s) that might confound the evaluations of benefit of zasocitinib therapy, including but not limited to rheumatoid arthritis, axial spondyloarthritis, systemic lupus erythematosus, Lyme disease, gout, or fibromyalgia.
The participant has a concomitant comorbid skin condition that, in the opinion of the investigator, would interfere with the study assessments, such as evidence of non-plaque PsO (erythrodermic, pustular, predominately guttate PsO, inverse, or drug-induced PsO).