Efficacy and Safety of Prurisol Administered Orally for Active Mild to Moderate Chronic Plaque Psoriasis

The total duration of study participation for an individual subject is approximately 112 days
(16 weeks) consisting of a Screening visit, followed within 21 days by Randomization and a
Treatment Period of 84 days, and a Follow-up Period of 28 days after the last day of study
drug treatment. A window of ± 3 days will be considered acceptable for conduct of each
scheduled visit following the first visit.

This study will require eight (8) scheduled subject visits:

x Visit 1: Screening (Up to Day 21) x Visit 2: Baseline (Day 0) x Visit 3: Day 14 Interim (±
3 days) x Visit 4: Day 28 Interim (± 3 days) x Visit 5: Day 42 Interim (± 3 days) x Visit 6:
Day 56 Interim (± 3 days) x Visit 7: Day 84 End of Treatment/Unscheduled/ET (± 3 days) x
Visit 8: Day 112 Follow-up (± 3 days)

Inclusion Criteria:

- Male or non-pregnant female adults aged 18 years with a clinical diagnosis of stable
(at least 6 months) plaque psoriasis, not including scalp or intertriginous areas.

- The extent of psoriasis must meet all of the following three (3) criteria:

- Total Body Surface Area (BSA) affected by plaque psoriasis of 10% to 20%
inclusive

- Investigator's Global Assessment (IGA) score of the severity of psoriasis of 2 or
3 (5- point ordinal scale)

- Identification of a target psoriatic lesion with a score of 3 on the Target
Lesion Assessment scale (5-point ordinal scale) for Scaling. (Other psoriatic
lesions may have lower scaling scores.)

- Females of reproductive potential must not be pregnant

- Female subjects with reproductive potential, if sexually active, must agree to use
reliable means of contraception

- The subject must agree to avoid prolonged exposure to the sun and avoid the use of
tanning booths or other ultraviolet light sources during the study.

- The subject must provide signed and dated written informed consent to participate in
the clinical study.

Exclusion Criteria:

- 1. Females of reproductive potential who are not using reliable contraception.

- Presence of any non-psoriatic uncontrolled (in the Investigator's medical opinion)
systemic disease. i

- Unstable forms of psoriasis, e.g. guttate, erythrodermic, exfoliative, palmoplantar,
nail, or pustular.

- Use within 6 months of biologic treatment for psoriasis

- Use within 24 months of chemotherapy or radiation therapy.

- Use within 2 months of any systemic immunosuppressive therapy.

- Use within 1 month of (1) systemic corticosteroids, (2) systemic antibiotics, (3)
systemic antipsoriasis treatments (e.g. methotrexate, corticosporin, hydroxyurea), (4)
PUVA therapy, (5) UVB, (6) systemic anti-inflammatory treatment.

- Use within 2 weeks of topical antipsoriasis drugs or topical corticosteroids or
topical retinoids.

- Presence of a condition (e.g., history of frequent consumption of substantial
quantities of alcohol, or an untreated psychiatric condition) that makes it unlikely
that the requirements of the protocol will be completed.

- History of any previous use of a Tumor Necrosis Factor (TNF) blocker or other
immunomodulating drug as therapy for psoriasis within the 6 months prior to screening.

- History of any allergic reaction to any formulation of abacavir.

- Previous treatment with any abacavir-containing product, e.g., Ziagen®, Epzicom®, or
Trizivir®.