An Efficacy and Safety Study of Ustekinumab (CNTO 1275) in Participants With Plaque Psoriasis

The purpose of this study is to evaluate the safety and efficacy of ustekinumab (CNTO 1275) compared with placebo in participants with moderate to severe plaque type psoriasis.

This is a multicenter (involving more than 1 study center), randomized (study medication assigned by chance), double-blind (neither the invesitigator nor the participant knows the identity of the study medication), placebo- controlled (1 of the study medications is inactive), parallel-group comparative study (different groups of participants will receive different treatments at the same time). The total duration of the study will be 78 weeks which will be comprised of: a screening period (6 weeks); an efficacy assessment period (64 weeks \[with a total of 7 treatments at Weeks 0, 4, 12, 16, 28, 40, and 52\]) and a follow-up assessment period (8 weeks). The efficacy assessment period will further include: a placebo-controlled treatment period (Weeks 0-12) and an active drug treatment period (Weeks 12-64). During the placebo-controlled treatment period, participants will receive ustekinumab (45 mg or 90 mg) subcutaneously (SC-into the muscles) or placebo SC. During the active drug treatment period, participants will continue treatment with 45 mg or 90 mg SC as assigned during the placebo-controlled treatment period; however, participants in the placebo group will be divided into 2 groups and will receive ustekinumab 45 mg (Placebo A) or 90 mg (Placebo B) SC. Efficacy will be evaluated primarily by analysis of psoriasis area and severity index (PASI) score. Participant safety will also be monitored.

Eligibility Criteria:
Inclusion Criteria:

* Participants diagnosed with psoriasis (psoriasis vulgaris and psoriatic arthritis) at least 6 months before registration
* Participants with plaque type psoriasis covering at least 10 percent of total body surface area at the time of informed consent and at registration
* Participants with a PASI score of greater than or equal to 12 at the time of informed consent and at registration
* Female participants of childbearing potential or males, whose partner can be pregnant, must agree that he/she will continuously take an appropriate contraceptive measure for 1 year from the day of informed consent to termination of the final investigational treatment; in the case of childbearing potential females, pregnancy test at screening must be negative
* Participants must agree not to receive Bacillus Calmette-Guérin (BCG) vaccination and live vaccine inoculation for 1 year after final treatment with the investigational product

Exclusion Criteria:

* Participants with guttate psoriasis, erythrodermic psoriasis, or pustular psoriasis
* Participants with a medical history of tuberculosis infection or suspected tuberculosis infection
* Participants with present or past history of chronic or recurrent infection (e.g., chronic or recurrent urinary tract infection or respiratory infection)
* Participants with a current serious infection (e.g., sepsis, hepatitis, pneumonia, or pyelonephritis) or those who experienced a serious infection within the 2 month period before registration and including participants who received intravenous administration of antibiotics or antiviral agents within the 2 month period before registration
* Participants with a current or past history of malignant tumors (except for basal cell carcinoma, intraepidermal squamous cell carcinoma in the skin and uterine cervical squamous cell carcinoma, whose treatment was completed and no sign suggesting a recurrence has been observed, and squamous cell carcinoma in the skin whose treatment was completed and no sign suggesting a recurrence has been observed in the past 5 years)