A Study of the Safety and Effectiveness of Ustekinumab in Patients With Psoriatic Arthritis

The purpose of this study is to evaluate the effectiveness (improvement of signs and symptoms) and safety of ustekinumab in participants with active psoriatic arthritis.

This is a randomized (participants are assigned different treatments based on chance), double-blind (neither the participant nor the physician knows whether drug or placebo is being taken, or at what dosage), parallel-group (each group of participants will be treated at the same time), and multicenter (study conducted at multiple sites) study. Approximately, 615 participants will participate in this study. Participants will be assigned to one of three treatment groups: Group I: ustekinumab 45 mg, Group II: ustekinumab 90 mg, and Group III: placebo group (an inactive substance). Participants will receive either 45 mg ustekinumab or 90 mg ustekinumab at Weeks 0, 4, and every 12 weeks until Week 88 as randomized to respective groups. Participants in placebo group will receive placebo at Weeks 0, 4, 16, and 20 and 45 mg ustekinumab at Weeks 24 and 28 followed by every 12 weeks dosing until Week 88. Participants who do not have greater than or equal to 5 percentage improvement in their disease (tender and swollen joints) will be eligible for an early escape. Specifically, during early escape at Week 16, participants in Group I will receive 90 mg ustekinumab, for participants in Group II same dosing schedule will be continued, and participants in placebo group will receive 45 mg ustekinumab. Safety evaluations will include assessments of adverse events, clinical laboratory tests, and physical examination. The maximum study duration will be approximately 108 weeks.

Eligibility Criteria:
Inclusion Criteria:

* Have had a documented diagnosis of psoriatic arthritis (PsA) at least 6 months
* Have a diagnosis of active PsA at the time of entry into the study
* If the participant is using methotrexate they should have started treatment at a dose not to exceed 25 milligram per week at least 3 months prior to the beginning of the study and should have no serious toxic side effects attributable to methotrexate. Methotrexate route of administration and doses should be stable for at least 4 weeks prior to the first administration of study agent. If currently not using methotrexate, must have not received methotrexate for at least 4 weeks prior to the first administration of the study agent

Exclusion Criteria:

* Have other inflammatory diseases, including but not limited to rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, or Lyme disease
* Have used any therapeutic agent targeted at reducing interleukin (IL)-12 or IL-23, including but not limited to ustekinumab and briakinumab (ABT-874)
* Have used any biologic agents that are targeted for reducing tumor necrosis factor-alpha, including but not limited to infliximab, etanercept, adalimumab, and golimumab
* Have a medical history of latent or active granulomatous infection
* Have any known malignancy or have a history of malignancy (with the exception of basal cell carcinoma, squamous cell carcinoma in situ of the skin, or cervical carcinoma in situ that has been treated with no evidence of recurrence, or squamous cell carcinoma of the skin that has been treated with no evidence of recurrence within 5 years of the beginning of the study