The primary purpose of this study is to evaluate the effectiveness and safety of ustekinumab (CNTO 1275) in the treatment of patients with moderate to severe plaque psoriasis.

This is a randomized (patients are assigned to different treatments based on chance), double blind (neither the patient nor the physician knows whether medication or placebo [an inactive substance that is compared with a medication to test whether the medication has a real effect in a clinical study] is being taken, or at what dosage), parallel-group (each group of patients are treated at the same time), multicenter study to determine the effectiveness and safety of two different doses of ustekinumab administered subcutaneously (under the skin) as compared with placebo in patients with moderate to severe plaque-type psoriasis (the most common type of psoriasis). 766 patients will be randomized to Group 1 (ustekinumab 45 mg), Group 2 (ustekinumab 90 mg) and Group 3 (placebo) at Week 0. The study was designed to evaluate the effectiveness and safety of 2 dose regimens of ustekinumab: (1) 45 mg at Weeks 0 and 4 followed by 45 mg every 12 weeks maintenance therapy (treatment designed to help the original primary treatment succeed) and (2) 90 mg at Weeks 0 and 4 followed by 90 mg every 12 weeks maintenance therapy. The study will consist of 4 periods: (1) Placebo-controlled portion of study [Week 0 to Week 12] during which the safety and effectiveness of 2 doses (45mg and 90mg) of ustekinumab will be compared to placebo; (2) Placebo crossover and active treatment portion of study [Week 12 to Week 40] during which patients randomized to receive placebo at Week 0 will crossover to receive ustekinumab, and all patients will receive active treatment; (3) Randomized withdrawal portion of study [beginning at Week 40] during which patients who received ustekinumab [45mg or 90mg every 12 weeks] at Week 0 and are responding to it, will be randomized either to placebo or continued maintenance therapy with ustekinumab; and (4) Long-term extension [from Week 52 to Week 264 (ie, 5 years)] period during which the safety and effectiveness of ustekinumab long-term use will be evaluated in patients.

Inclusion Criteria:

• Patients with plaque-type psoriasis diagnosed at least 6 months prior and covering at least 10% of total body surface areas
• Have psoriasis area-and-severity index score of >=12
• Patients who are considered by treating dermatologist to be a candidate for phototherapy or systemic treatment of psoriasis
• Have no history of latent or active TB

Exclusion Criteria:

• Currently have nonplaque forms of psoriasis or drug-induced psoriasis
• Have any therapeutic agent targeted at reducing IL-12 or IL-23
• Have had a BCG vaccination within the previous 12 months
• Have a history of chronic or recurrent infectious disease or who have or have had a serious infection requiring hospitalization or intravenous antibiotics within the previous 2 months
• Have or ever have had a nontuberculous mycobacterial infection or opportunistic infection
• Patients known to be infected with human immunodeficiency virus, hepatitis B, or hepatitis C
• Have current signs or symptoms of severe, progressive, or uncontrolled renal, hepatic, hematological, gastrointestinal, endocrine, pulmonary, cardiac, neurologic, cerebral, or psychiatric disease
• Patients with a malignancy or who have a history of malignancy (with the exception of certain skin cancers and pre-invasive cervical cancer)

Generally, the only disclosure restriction on the PI is that the sponsor has 60 days to review results communications prior to public release and can embargo communications regarding trial results for a period that does not exceed 180 days from the time submitted to the sponsor for review. The sponsor cannot require changes to the communication and cannot extend the embargo.