Efficacy and Safety Study of Guselkumab in the Treatment of Participants With Active Psoriatic Arthritis (PsA)

This is a multi-center (more than one clinical site will work on a medical research study),
randomized (study medication assigned to participants by chance), double-blind (neither
investigator nor participant knows which treatment the participant receives),
placebo-controlled (placebo is an inactive substance that is compared with a drug to test
whether the drug has a real effect in a clinical trial) study to determine the efficacy and
safety of guselkumab in participants with PsA. The study will consist of 4 parts: Screening
period (6 weeks), a double-blind treatment period (consists of guselkumab and placebo
treatment for 24 weeks), an active treatment period (guselkumab for 20 weeks), and follow-up
period (12 weeks). The maximal study duration for a participant will not exceed 62 weeks
including the Screening period. Eligible participants will be randomly assigned to one of
two groups in a 2:1 ratio to either receive Guselkumab 100 milligram (mg) at Weeks 0, 4 then
every 8 weeks or Placebo at Weeks 0, 4 then every 8 weeks until Week 24. At week 24,
participants remaining in the placebo group will start to receive guselkumab 100 mg at Weeks
24, 28, 36 and 44. Participants in both treatment groups who have less than (<) 5 percent
(%) improvement from baseline in both tender and swollen joint counts at Week 16 will
qualify for early escape and will switch to open-label therapy with ustekinumab 45 mg or 90
mg at Weeks 16, 20, 32, and 44 based on the approved dosage for the PsA indication in the
particular country of study. The efficacy will be assessed primarily by measuring percentage
of participants who achieve an American College of Rheumatology (ACR) 20 Response at Week
24. Participants' safety will be monitored throughout the study.

Inclusion Criteria:

- Has had Psoriatic Arthritis (PsA) for at least 6 months before the first
administration of study drug and meet classification criteria for Psoriatic Arthritis
(CASPAR) at Screening

- Had active PsA as defined by:

1. At least 3 swollen joints and at least 3 tender joints at Screening and at
baseline

2. C-reactive protein (CRP) greater than or equal to (>=) 0.3 milligram
(mg)/deciliter (dL) at Screening from the central laboratory

- Has 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

- Has plaque psoriasis with body surface area (BSA) involvement greater than or equal
to (>=) 3% at Screening and baseline

- Has active PsA despite current or previous non-biologic disease-modifying
antirheumatic drugs (DMARD), oral corticosteroid, and/or nonsteroidal
anti-inflammatory drug (NSAID) therapy

- If using methotrexate (MTX), oral corticosteroids or NSAIDs, the dose must be stable

Exclusion Criteria:

- Have other inflammatory diseases that might confound the evaluations of benefit of
guselkumab therapy, including but not limited to rheumatoid arthritis (RA),
ankylosing spondylitis (AS), systemic lupus erythematosus, or Lyme disease

- Has previously received guselkumab or ustekinumab

- Has received more than 1 type of biologic anti-tumor necrosis factor (TNF) agent
previously

- Have received infliximab (or its biosimilars) or golimumab intraveneous (IV) within
12 weeks before the first administration of study drug

- Have received adalimumab (or its biosimilars), golimumab subcutaneous (SC),
certolizumab pegol or etanercept (or its biosimilars) within 8 weeks before the first
administration of study drug