Clinical Trial Finder

Inclusion Criteria:

Part 1:

• - Healthy on the basis of physical examination, medical history, vital signs, and 12-lead electrocardiogram (ECG) performed at screening.

Any abnormalities, must be considered not clinically significant and this determination must be recorded in the participant's source documents and initialed by the investigator.

• - Has a negative severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Coronavirus disease 2019 [COVID-19]) reverse transcription polymerase chain reaction (RT-PCR) test within 72 hours prior to study intervention administration.

• - Body weight within 50 kilograms (kg) to 100 kg and body mass index (BMI) within the range 18 kilograms per meter square (kg/m^2) to 30 kg/m^2 (inclusive) Parts 2 and 3: - Have a diagnosis of psoriatic arthritis (PsA) for at least 3 months before the first administration of study agent and meet classification criteria for psoriatic arthritis (CASPAR) at screening.

• - Have active plaque psoriasis.

Exclusion Criteria:

Part 1:

• - History or current signs and symptoms of liver or renal insufficiency, significant cardiac, vascular, pulmonary, gastrointestinal, endocrine, neurologic, hematologic, rheumatologic, psychiatric, genitourinary, or metabolic disturbances.

• - Had major illness or surgery (example, requiring general anesthesia) within 12 weeks before screening, or will not have fully recovered from illness or surgery, or has surgery planned during the time the participant is expected to participate in the study or within 21 weeks after the last dose of study intervention administration.

Parts 2 and 3:

• - History or current signs and symptoms of severe, progressive, or uncontrolled liver or renal insufficiency, significant cardiac, vascular, pulmonary, gastrointestinal, endocrine, neurologic, hematologic, rheumatologic (with the exception of PsA), psychiatric, genitourinary, or metabolic disturbances.

- A nonplaque form of psoriasis (example, erythrodermic, guttate, or pustular)

Arms

Experimental: Part 1: Healthy Participants-Coadministration

Healthy participants will receive a single co-administered dose of risankizumab and guselkumab subcutaneously (SC) on Day 1.

Experimental: Part 2: Psoriatic Arthritis (PsA) Participants-Coadministration

Participants with PsA will receive a single co-administered dose of risankizumab and guselkumab SC on Day 1 and Day 29.

Experimental: Part 3: PsA Participants-Separate Administration

Participants with PsA will receive a single dose of either risankizumab or guselkumab SC on Day 1 and Day 29.

Interventions

Drug: - Guselkumab

Guselkumab will be administered subcutaneously.

Drug: - Risankizumab

Risankizumab will be administered subcutaneously.