Biological Effects of LEO 43204 in Actinic Keratosis

This is a Phase I, single-centre, open label, within-subject comparison trial to explore the biological effects of LEO 43204 Gel, 0.037%, applied once daily for 3 consecutive days in patients with actinic keratosis on the upper extremity. The treatment area for each patient will be as defined as a contiguous area of 250 cm2 of skin on the upper extremity (including the dorsum manus) that contains a minimum of 5 AK lesions. Additionally there must be at least one AK lesion located in a non-treated area on the contralateral arm. All eligible subjects will receive LEO 43204 Gel, 0.037%, on the treatment area on Days 1, 2 and 3. Study medication application will be (sub)investigator applied. A total of 30 patients will be enrolled into this study (n=15 in each of the two groups). Patients will be divided into two groups with different biopsy schedules.