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

This study is a randomized (patients are assigned different treatments based on chance), double blind (neither the patient nor the physician knows whether drug or placebo is being taken, or at what dosage), parallel-group, multicenter study to evaluate the effectiveness and safety of ustekinumab compared to placebo in the treatment of patients with active psoriatic arthritis. The primary effectiveness endpoint will be measured by the reduction in signs and symptoms of arthritis, as defined by 20% improvement from baseline in American College of Rheumatology (ACR) measurements of arthritis at Week 24. The study will additionally look at higher levels of joint improvement (i.e. 50% or 70% improvement from baseline) and improvement in activity and quality of life, as well as the impact of ustekinumab on psoriatic skin lesions. Safety assessments will be performed throughout the study and include obtaining and evaluating laboratory tests, vital signs (e.g., blood pressure) and the occurrence and severity of adverse events (side effects). Patients will be assigned to one of three treatment groups. Patients will receive either 45 mg ustekinumab, 90 mg ustekinumab or placebo at weeks 0, 4 and every 12 weeks until week 88. Patients who do not have >=5% improvement in their disease (tender and swollen joints) at week 16 may be eligible to receive an increase or change to their ustekinumab dosage. Ustekinumab 45 mg, 90 mg, or placebo subcutaneous injections at Weeks 0 and 4 followed by every 12 week dosing with the last dose at Week 88. Early escape possibility at Week 16. Patients randomized to placebo will crossover to receive ustekinumab at Weeks 24 and 28 followed by every 12 week dosing with the last dose at Week 88. Expected duration of exposure to study agent is 100 weeks.

• Drug: placebo
  SC at Wks 0, 4, 16, 20, 24, 28, 40, 52, 64, 76, and 88
• Drug: placebo
  2 SC at Wks 0, 4, 16 & 20
• Drug: ustekinumab
  If Early Escape, 90 mg SC at Wk 16 & every 12 wks to Wk 88
• Drug: ustekinumab
  45 mg SC at Wk 24, 28 & every 12 wks to Wk 88
• Drug: ustekinumab
  45 mg SC at Wks 0, 4 and every 12 wks to Wk 88
• Drug: ustekinumab
  90 mg SC at Wks 0, 4 and every 12 wks to Wk 88
• Drug: placebo
  SC at Wks 0, 4, 16, 20, 24, 28, 40, 52, 64, 76 and 88
• Drug: ustekinumab
  If Early Escape, 45 mg SC at Wk 16, 20, 28 & every 12 wks to Wk 88

• 001: Experimental
  placebo SC at Wks 0 4 16 20 24 28 40 52 64 76 and 88,ustekinumab 45 mg SC at Wks 0 4 and every 12 wks to Wk 88,ustekinumab If Early Escape 90 mg SC at Wk 16 & every 12 wks to Wk 88
  Interventions:

  • Drug: placebo
  • Drug: ustekinumab
  • Drug: ustekinumab
• 002: Experimental
  placebo SC at Wks 0 4 16 20 24 28 40 52 64 76 and 88,ustekinumab 90 mg SC at Wks 0 4 and every 12 wks to Wk 88
  Interventions:

  • Drug: ustekinumab
  • Drug: placebo
• 003: Experimental
  placebo 2 SC at Wks 0 4 16 & 20,ustekinumab 45 mg SC at Wk 24 28 & every 12 wks to Wk 88,ustekinumab If Early Escape 45 mg SC at Wk 16 20 28 & every 12 wks to Wk 88
  Interventions:

  • Drug: placebo
  • Drug: ustekinumab
  • Drug: ustekinumab

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 patient is using methotrexate they should have started treatment at a dose not to exceed 25 mg/week at least 3 months prior to the beginning of the study and should have no serious toxic side effects attributable to methotrexate

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 IL-12 or IL-23, including but not limited to ustekinumab and ABT-874
• Have used any biologic agents that are targeted for reducing TNF-alpha, including but not limited to infliximab, etanercept, adalimumab, and golimumab
• Have a medical history of latent or active granulomatous infection, including TB, histoplasmosis, or coccidioidomycosis, prior to screening
• 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