A Study to Evaluate Safety and Efficacy of Toreforant (JNJ-38518168) in Participants With Moderate to Severe Plaque-type Psoriasis

This is a randomized (study medication assigned to participants by chance), double-blind (neither the researchers nor the participants know what treatment the participant is receiving), parallel-group, placebo-controlled (an inactive substance; a pretend treatment \[with no drug in it\] that is compared in a clinical trial with a drug to test if the drug has a real effect) study. The study consists of Screening Phase (maximum of 42 days prior to Week 0), Treatment Phase (Week 0-12) and Follow-up Phase (up to Week 16). Participants will be randomly assigned to receive JNJ-38518168 (3 milligram \[mg\] or 30 mg or 60 mg) or placebo once daily. The initial group of the participants will be randomized to either JNJ-38518168 30 mg or placebo. The dose assignments for the subsequent participants will depend on the results of up to 2 interim analyses. Efficacy will be primarily assessed by percentage of participants who achieve a Psoriasis Area and Severity Index (PASI) 75 response at Week 12. Participants' safety will be monitored throughout the study.