Phase 3b Safety and Efficacy Study of Apremilast to Treat Moderate to Severe Plaque-plaque Psoriasis

This study will test the clinical effectiveness and safety of apremilast compared with placebo as well as etanercept compared with placebo in the same group of patients with moderate to severe plaque psoriasis.

This is a phase 3b, multicenter, randomized, placebo-controlled, double-blind, double-dummy, study of the efficacy and safety of apremilast, etanercept, and placebo, in adults with moderate to severe plaque psoriasis.

250 participants will be randomized 1:1:1 to the three treatment groups. All subjects will receive both tablets and injections through Week 16.

The study will consist of four phases:

* Screening Phase - up to 35 days
* Double-blind Placebo-controlled Phase - Weeks 0-16
* Apremilast Extension Phase - Weeks 16-104
* Post-treatment Observational Follow-up Phase

During the double-blind, placebo-controlled phase, subjects will receive treatment with one of the following:

* apremilast (APR) 30 mg tablets orally twice a day (BID) plus once weekly (QW) evaluator/subject-blinded subcutaneous (SC) saline (placebo) injections (1 mL x 2 injections SC), or
* etanercept (ETN) 50 mg evaluator/subject-blinded subcutaneous (SC) once weekly (QW) injections (2 x 25 mg) plus placebo tablets orally twice a day (BID), or
* placebo tablets and evaluator/subject-blinded subcutaneous (SC) saline (placebo) injections.

All subjects will be asked to participate in a 4-week Post-treatment Observational Follow-up Phase either upon completion of the study or upon discontinuation of investigational product for those subjects who terminate the study early.

Eligibility Criteria:
Inclusion Criteria:

* Males or females, ≥ 18 years of age
* Diagnosis of chronic, moderate to severe plaque psoriasis for at least 12 months prior to Screening, and a candidate for phototherapy and/or systemic (including etanercept) therapy
* Had an inadequate response, intolerance, or contraindication to at least 1 conventional systemic agent for the treatment of psoriasis.
* No prior exposure to biologics for treatment of psoriatic arthritis or psoriasis

Exclusion Criteria:

* Other than psoriasis, history of any clinically significant and uncontrolled systemic diseases; any condition, including the presence of laboratory abnormalities, which would place the subject at unacceptable risk if he/she were to participate in the study.
* Pregnant or breast feeding.
* Have failed more than 3 systemic agents for treatment of psoriasis.
* History of allergy to any component of the investigational product (IP), including human immunoglobulin (Ig) proteins or allergy to etanercept.
* Hepatitis B surface antigen or anti-hepatitis C antibody positive at Screening.
* Latent, active tuberculosis (TB) or inadequately treated TB; nontuberculous mycobacterial infection or opportunistic infection (eg, cytomegalovirus, Pneumocystis carinii, aspergillosis, Clostridium difficile).
* Have a history of, or ongoing, chronic or recurrent infectious disease
* Have received, or are expected to receive, any live virus or bacterial vaccination within 3 months before first administration of IP, or through Week 20 during the study.
* Had a Bacillus Calmette-Guérin (BCG) vaccination within 1 year prior to screening.
* History of positive human immunodeficiency virus (HIV), or have congenital or acquired immunodeficiency (eg, common variable immunodeficiency disease).
* Active substance abuse or a history of substance abuse within 6 months prior to Screening.
* Malignancy or history of malignancy, except for treated \[ie, cured\] basal cell or squamous cell in situ skin carcinomas and cervical intraepithelial neoplasia \[CIN\] or carcinoma in situ of the cervix with no evidence of recurrence within the previous 5 years.
* Psoriasis flare or rebound within 4 weeks prior to Screening.
* Topical therapy within 2 weeks of randomization or systemic therapy for psoriasis within 4 weeks prior to randomization
* Use of phototherapy within 4 weeks prior to randomization or prolonged sun exposure or use of tanning booths or other ultraviolet (UV) light sources.
* Any investigational drug within 4 weeks prior to randomization, or 5 pharmacokinetic/pharmacodynamic half lives, if known (whichever is longer).
* Prior treatment with apremilast or etanercept.