Study to Determine the Maximum Tolerated Dose and Safety of PEP005 Topical Gel

Actinic keratoses (AK) is a common skin condition characterized by rough, scaly patches or sores on the top layer of the skin which if left untreated can progress to skin cancer. Current treatments can cause scarring and hypopigmentation, be inconvenient, or require long treatment duration. Non-invasive alternative therapy for treatment of AK lesions is thus being researched.

This is an open label, dose escalation, cohort study to determine the maximum tolerated dose (MTD) of PEP005 Topical Gel, administered once daily for two consecutive days (90 ul gel applied topically over a 3 x 3cm template surrounding a target lesion), to patients with actinic keratoses (AK). The study will be conducted in one centre in the US. Three patients will be entered initially at the lowest dose level (0.01%) with up to an additional three patients to be entered in the event of a dose limiting toxicity (DLT) in the initial patients. DLT are defined as 'severe' local skin reactions observed by the Investigator, either prior to treatment on Day 2 ( following treatment on Day 1 ) or observed on Day 8 (following treatment on Day 2). Based on findings from phase I studies and the low systemic absorption found in non-clinical toxicokinetic evaluations, no systemic toxicity is anticipated.Once determined A total of 10 patients will be treated at the MTD in order to confirm it's determination. Based on findings from the phase I study, the starting dose will be 0.01% PEP005 Gel.

Secondary objectives of the study are (1) evaluate the clinical efficiency of PEP005 Topical Gel, when administered once daily for two consecutive days and (2) determine the systemic absorption of PEP005 Topical Gel at the MTD . Hematologic and biochemical assessments will be undertaken at the screening visit and at days 8 and 29 . Adverse events will be assessed at every study visit. Clinical response to treatment will be assessed at Days 8, 15 and 29.