Onercept in the Treatment and Re-Treatment of Subjects With Moderate to Severe Plaque Psoriasis

Inclusion Criteria:

• Written informed consent, given prior to any study-related procedure not part of thesubject's normal medical care, with the understanding that consent may be withdrawn bythe subject at any time without prejudice to his or her future medical care

• At least 18 years of age

• Female subjects must be neither pregnant nor breast-feeding, and must lackchildbearing potential, as defined by either:

• Being post-menopausal (that is at least 12 months passed last menses) orsurgically sterile, or

• Using an effective form of contraception (that is, condoms, oral contraceptivesor intrauterine device) (Confirmation that the subject is not pregnant must beestablished by a negative urinary human chorionic gonadotrophin test within 7days before Study Day 1. A pregnancy test is not required if the subject ispost-menopausal or surgically sterile)

• An out-patient status at the time of enrollment

• Plaque psoriasis for at least 12 months

• Plaque psoriasis covering at least 10 percent of total body surface area and a PASIscore of 12.0 or more

• Candidate for phototherapy or systemic therapy

• Static Physician's Global Assessment (sPGA) of 3 or more

Exclusion Criteria:

• Use of more than one Non-steroidal anti-inflammatory drug (NSAID) to treat psoriaticarthritis or having a change in chronic NSAID regimen during the 28 days before StudyDay 1 to treat psoriatic arthritis

• Previous systemic treatment with biologics, including interferon, and/orcytokines/anti cytokines (for example, anti- tumor necrosis factor-alpha, anti-clusterof differentiation [CD]4, interleukin [IL]-10, IL-1ra, anti-CD11a, etc.) within 3months before Study Day 1

• Participation in any other investigational study or experimental therapeutic procedureconsidered to interfere with the study within 3 months before Study Day 1

• Treatment with any systemic corticosteroids or intra-articular corticosteroidinjection during the 28 days before Study Day 1

• Experimental or off-label treatments for psoriasis and/or psoriatic arthritis such asazathioprine, hydroxyurea / hydroxycarbamide, mycophenolate, chlorambucil, leflunomideor cyclophosphamide within 1 year prior to Study Day 1

• Treatment with cyclosporin, methotrexate, oral retinoids (that is, acitretin), orfumaric acid esters within 28 days (3 months for acitretin) before Study Day 1

• Treatment with any topical therapies, such as Vitamin D derivatives, corticosteroids,tars and tar oils, dithranol for chronic or short contact therapy, salicylic acid andtopical retinoids, within 14 days before Study Day 1

• Phototherapy within 28 days before Study Day 1

• Use of tanning booths within 14 days before Study Day 1

• Abnormal liver function, defined by a total bilirubin greater than or equal to 1.2times the upper limit of normal values, (except in the case of Gilbert's syndrome), oraspartate aminotransferase, alanine aminotransferase or alkaline phosphatase levelsgreater than or equal to 2.5 times the upper limit of normal values

• Inadequate bone marrow reserve, defined as:

• Leukocytes less than or equal to 3.5 * 10^9 per liter (/L), or

• Thrombocytes less than or equal to 100 * 10^9 /L, or

• Hemoglobin less than or equal to 5 millimole per liter (mmol/L) (8.9 gram perdeciliter).

• Abnormal renal function, defined by serum creatinine greater than 150 micromole perliter.

• Sero-positivity for human immunodeficiency virus (HIV), Hepatitis B surface antigen (HBsAg), or Hepatitis C virus (HCV)

• Planned major surgery within the treatment period of the study.

• History of cancer in the preceding 5 years (except adequately treated basal cellcarcinoma of the skin or squamous cell carcinoma in situ of the skin). Any history ofhematopoietic cancer

• History of active tuberculosis, current active tuberculosis or candidacy forprophylactic therapy for tuberculosis

• Active severe infection (or non-severe infection at the discretion of theInvestigator).

• History of any opportunistic infection (for example, viral, fungal, protozoal, orbacterial) in the 6 months preceding Study Day 1 related to any clinical condition ofimmunodeficiency

• Clinically significant and serious abnormalities on electrocardiography or chestX-ray, (at the discretion of the Investigator)

• Other serious concomitant disorders incompatible with the study. In particular,subjects with congestive heart failure, prior or current history of blood dyscrasia orcentral nervous system demyelinating disorders should not be included in the study

• History of or current drug (including narcotics) abuse, or current active problemswith alcohol abuse

• Requirement for immunization, allergy desensitization or vaccination during the entirestudy period (it is recommended that these procedures be scheduled at least 14 daysprior to Study Day 1 or greater than 3 months after the last injection of study drug),with the exception of killed influenza vaccines which are allowed at any time duringthe study

• Guttate, erythrodermic or pustular psoriasis as sole or predominant form of psoriasis.

• Evidence of skin conditions other than psoriasis (for example, eczema) that wouldinterfere with psoriasis disease assessments

• Clinically significant psoriasis flares during screening or at the time of enrollmentnecessitating immediate relief (at the Investigator's discretion)

• Live or killed virus or bacteria vaccines (within 14 days before Study Day 1) with theexception of killed influenza vaccines which are allowed both prior to Study Day 1 andat any time during the study

• Bedridden status

• Previous use of onercept