A Phase 2 Study of Cellular and Immunologic Changes in the Skin of Subjects Receiving PH-10

• Topical Rose Bengal, 0.005% (Drug), also known as PH-10: Subjects will apply PH-10 vehicle daily for 28 consecutive days followed by active PH-10 daily for 28 consecutive days to their plaque psoriasis areas on the trunk or extremities (excluding palms, soles, scalp, facial and intertriginous sites).

Primary outcomes

• Change in the immunologic, structural and hyperproliferative state of the skin in the target plaque and evidence of cellular atypia following PH-10 application [28 days]

Secondary outcomes

• Psoriasis Severity Index (PSI) changes from pre-treatment [28 days]
• Plaque Response changes from Day 1 pre-treatment [28 days]
• Pruritus Self-Assessment score changes from Day 1 pre-treatment [28 days]
• Correlation of PSI changes with observed histopathologic and immunohistopathologic changes in the skin of the target plaque [28 days]
• Incidence of adverse experiences [28 days]
• Incidence of adverse changes in clinical laboratory tests [28 days]
• Incidence of adverse changes in weight or vital signs [28 days]
• Correlation of adverse experiences with observed histopathologic and immunohistopathologic changes in the skin [28 days]

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Men or women, age 18 or older.
* Presence of mild to moderate plaque psoriasis on the trunk or extremities (excluding palms, soles, scalp, and facial or intertriginous areas).
* At least one target plaque having a minimum diameter of 5 cm (2 inches) with uniform mild to moderate plaque psoriasis.
* Fitzpatrick skin type I-VI.
* Written informed consent by the subject or legal guardian.

Exclusion Criteria:

* Female subjects of childbearing potential who are pregnant, attempting to conceive, not using effective contraception, or who are nursing an infant.
* Subjects who have received PH-10.
* Subjects who have received PUVA or systemic antipsoriatic therapy (immunosuppressants, cytostatics, corticosteroids) within 28 days of study initiation (14 days for methotrexate).
* Subjects who have received UVB light therapy within 14 days of study initiation.
* Subjects who have received topical antipsoriatic therapy (including corticosteroids, tar, anthralin or Vitamin D analogs) to the study plaque areas within 14 days of study initiation.
* Subjects who have received any approved or investigational biologic drug therapy for psoriasis within 90 days or 5 half-lives of study initiation.
* Subjects who have participated in a clinical research study within 28 days of study initiation.
* Subjects with a history of porphyria, systemic lupus erythematosus or xeroderma pigmentosum.
* Subjects with clinical conditions that, in the opinion of the Investigator, may pose a health risk to the subject because of involvement in the study or detrimentally affect regular follow-up of the subject.

• Eric Wachter, Ph.D., Study director, Provectus Biopharmaceuticals, Inc.