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

Placebo 0.5 ml and 1.0 ml will be administered subcutaneously (SC) on Weeks 0 and 4 respectively during the controlled period (Weeks 0-12).

Ustekinumab 45 mg (0.5 ml) and placebo (1.0 ml) will be administered SC on Weeks 0 and 4 during controlled period (Weeks 0-12).

Ustekinumab 90 mg (1.0 ml) and placebo (0.5 ml) will be administered SC on Weeks 0 and 4 during controlled period (Weeks 0-12).

After the controlled period (i.e., during the active drug treatment period \[Weeks 12-64\]), the placebo group will be randomized into 2 groups, including Placebo A, in which ustekinumab 45 mg (0.5 ml) and placebo (1.0 ml) will be administered SC at Weeks 12, 16, 28, 40, and 52.

After the controlled period (i.e., during the active drug treatment period \[Weeks 12-64\]), the placebo group will be randomized into 2 groups, including Placebo B, in which ustekinumab 90 mg (1.0 ml) and placebo (0.5 ml) will be administered SC at Weeks 12, 16, 28, 40, and 52.

After the controlled period (i.e., during the active drug treatment period \[Weeks 12-64\]), participants in the ustekinumab 45 mg group will receive placebo (0.5 ml and 1.0 ml) SC at Week 12 followed by ustekinumab 45 mg (0.5 ml) and placebo (1.0 ml) SC at Weeks 16, 28, 40 and 52.

After the controlled period (i.e., during the active drug treatment period \[Weeks 12-64\]), participants in the ustekinumab 90 mg group will receive placebo (0.5 ml and 1.0 ml) SC at Week 12 followed by ustekinumab 90 mg (1.0 ml) and placebo (0.5 ml) SC at Weeks 16, 28, 40 and 52.