A Study of Guselkumab in the Treatment of Participants With Moderate to Severe Plaque-Type Psoriasis

The purpose of this study is to evaluate the efficacy, safety, and tolerability of guselkumab (CNTO 1959) in the treatment of participants with moderate to severe plaque-type psoriasis.

This is a randomized (assignment of study drug by chance), double-blind (neither the participant or study staff will know the identity of study drugs), placebo- (inactive substance identical in appearance to study drug) and active-comparator-controlled (use of an approved drug to compare with study drug) study of guselkumab in participants with moderate to severe plaque-type psoriasis (scaly skin rash). The active comparator study drug is adalimumab, an approved drug for the treatment of moderate to severe plaque psoriasis. Participants who satisfy all inclusion and exclusion criteria will be randomly assigned in a 2:1:2 ratio to one of three treatment groups (arms): Group I (guselkumab 100 mg dose regimen), Group II (placebo then crossover to guselkumab at Week 16), or Group III (adalimumab at standard psoriasis dosing). All participants will receive guselkumab every 8 weeks (q8w) from Week 52 through Week 252 (open label treatment period).The end of the study is defined as the time the last participant completes the Week 264 visit. Participants will primarily be assessed for Investigator's Global Assessment (IGA) Score of 0 or 1 and Psoriasis Area and Severity Index (PASI) 90 Response at Week 16. The total duration of the study will be approximately 268 weeks (includes a 4-week screening period). Participants will be monitored for safety throughout the study.

Eligibility Criteria:
Inclusion Criteria:

* Have a diagnosis of plaque-type psoriasis (with or without psoriatic arthritis) at least 6 months before the first administration of study agent
* Have a Psoriasis Area and Severity Index (PASI) greater than or equal to (\>=) 12 at Screening and at Baseline
* Have an Investigator's Global Assessment (IGA) score \>=3 at Screening and at Baseline
* Have an involved body surface area (BSA) \>=10 percent (%) at Screening and at Baseline
* Must be a candidate for either systemic therapy or phototherapy for psoriasis

Exclusion Criteria:

* Participants with nonplaque forms of psoriasis (for example, erythrodermic, guttate, or pustular) or with current drug-induced psoriasis (for example, a new onset of psoriasis or an exacerbation of psoriasis from beta blockers, calcium channel blockers, or lithium)
* Participants who have ever received guselkumab or adalimumab
* History or current signs or symptoms of severe, progressive, or uncontrolled renal, hepatic, cardiac, vascular, pulmonary, gastrointestinal, endocrine, neurologic, hematologic, rheumatologic, psychiatric, or metabolic disturbances
* Has any condition that, in the opinion of the investigator, would make participation not be in the best interest (for example, compromise the well-being) of the participant or that could prevent, limit, or confound the protocol-specified assessments
* Is pregnant, nursing, or planning a pregnancy (both men and women) within 5 months following the last administration of study drug