• The primary endpoint is the proportion of subjects who achieve >= 75% improvement in the psoriasis area-and-severity index from baseline at Week 12.
  

• Major secondary endpoints are the proportions of subjects with clear or minimal disease at Week 12 by Physician Global Assessment, the improvement in the Dermatology Life Quality Index, and the evaluation of dosing interval adjustment.
  

Although numerous therapeutic options exist for the treatment of psoriasis, there is still a significant unmet medical need due to the limited effectiveness and/or significant side effect profile of current treatment options. Preclinical studies and early phase clinical studies suggest that interleukins-12 and -23, two molecules that are part of the communication network in the immune system, may play an important role in psoriasis. CNTO 1275 is a monoclonal antibody directed against interleukins -12 and 23. This is a randomized, double blind, parallel-group, multicenter study to determine the effectiveness and safety of two different doses of CNTO 1275 administered subcutaneously as compared with placebo in patients with moderate to severe plaque-type psoriasis (the most common type of psoriasis). The hypothesis is that CNTO 1275 will be more effective in treatment of psoriasis than placebo, that the improvement in psoriasis will result in an improved quality of life for treated patients and that CNTO 1275 will be generally well tolerated. Patients will receive CNTO 1275, 45 or 90 mg, or placebo administered subcutaneously at weeks 0 and 4 weeks then every 12 weeks thereafter until week 52. For subjects who partially respond to the starting regimen, the dosing interval may be adjusted to every 8 weeks. Patients will enter long term extension portion of the study at week 52 during which subjects will continue to receive treatment with CNTO 1275 and will be followed for a total of up to 264 weeks from the initial (week 0) administration of study agent.

The dose of CNTO 1275 will be 45 or 90 mg or placebo administered subcutaneously at weeks 0 and 4 weeks then every 12 weeks thereafter. For subjects who partially respond to the starting regimen, the dosing interval may be adjusted to every 8 weeks.