Clinical Trial Finder

Inclusion Criteria:

• - Have a diagnosis of psoriatic arthritis (PsA) for at least 3 months before the first administration of study intervention and meet classification criteria for psoriatic arthritis (CASPAR) 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 (b) C-reactive protein (CRP) greater than or equal to (>=) 0.1 milligrams per deciliter (mg/dL) at screening from the central laboratory.

• - 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 active plaque psoriasis with at least one psoriatic plaque of >= 2 cm diameter or nail changes consistent with psoriasis.

• - A female participant of childbearing potential must have a negative highly sensitive serum pregnancy test (Beta-hCG) at screening and a negative urine pregnancy test at Week 0 prior to administration of study intervention.

Exclusion Criteria:

• - Has previously received any biologic disease-modifying antirheumatic drugs (DMARDs) for PsA or psoriasis.

• - Has a history or current signs or symptoms of severe, progressive, or uncontrolled renal, hepatic, cardiac, vascular, pulmonary, gastrointestinal, endocrine, neurologic, hematologic, rheumatologic (with the exception of PsA), psychiatric, genitourinary, or metabolic disturbances.

• - Has known allergies, hypersensitivity, or intolerance to icotrokinra or its excipients.

• - Has other inflammatory diseases that might confound the evaluations of benefit of icotrokinra therapy, including but not limited to rheumatoid arthritis (RA), systemic lupus erythematosus, or lyme disease.

- Participants with fibromyalgia or osteoarthritis symptoms that, in the investigator's opinion, would have potential to interfere with efficacy assessments

Arms

Experimental: Group I: Icotrokinra Dose 1

Participants will receive icotrokinra dose 1. Participants who continue into a long term extension (LTE) will continue to receive icotrokinra dose 1.

Experimental: Group II: Icotrokinra Dose 2

Participants will receive icotrokinra dose 2. Participants who continue into a LTE will continue to receive icotrokinra dose 2.

Placebo Comparator: Group III: Placebo

Participants will receive placebo matched to icotrokinra and will cross over to receive icotrokinra dose 1 or dose 2. Participants who continue into the LTE will continue to receive icotrokinra dose 1 or dose 2.

Active Comparator: Group IV: Active Reference Comparator

Participants will receive active reference drug, ustekinumab. Participants who continue into a LTE will cross-over to receive icotrokinra dose 1 or dose 2.

Interventions

Drug: - Icotrokinra

Icotrokinra will be administered.

Drug: - Placebo

Placebo will be administered.

Drug: - Active reference comparator

Active reference comparator drug will be administered.