A multicenter, randomized, vehicle-controlled phase 2 study of blue light photodynamic therapy with aminolevulinic acid HCl 20% topical solution for the treatment of actinic keratoses on the upper extremities: the effect of occlusion during the drug incubation period.

Background: Photodynamic therapy (PDT) with aminolevulinic acid (ALA) has been shown to be safe and effective in the treatment of actinic keratoses (AKs) of the face and scalp. A recent small study has suggested that ALA-PDT can be effective for AKs of the dorsal hands/forearms. However, studies designed to provide sufficient statistical power to test this hypothesis are lacking in the literature.

Objective: To determine and compare the safety and efficacy of blue light ALA-PDT vs blue light placebo vehicle (VEH) in the treatment of AKs of the upper extremities and to evaluate the effect of occlusion after application of ALA vs VEH.

Methods: ALA or VEH was applied to both dorsal hands/forearms for the 3-hour incubation period before blue light treatment (10 J/ cm2). One extremity of each subject was covered with occlusive dressing during the incubation period. Treatment was repeated at week 8 if any AK lesions remained.

Results: The median AK lesion clearance rate at week 12 was 88.7% for extremities treated with occluded ALA (ALA+OCC), 70.0% for extremities treated with nonoccluded ALA, 16.7% for extremities treated with occluded VEH (VEH+OCC), and 5.6% for extremities treated with nonoccluded VEH (P<.0001). ALA+OCC resulted in a significantly higher clearance rate compared with the nonoccluded extremity at weeks 8 (P=.0006) and 12 (P=.0029). Thirty-four percent (12/35) of extremities treated with ALA+OCC had complete clearance of lesions at week 12 compared with 0% (0/35) of extremities treated with VEH+OCC (P=.0002). The safety pro!le in this study is consistent with previously reported side effects of the therapy.

Conclusions: Blue light ALA-PDT following a 3-hour incubation appears efficacious for AK clearance of the upper extremities. Incubation using an occlusive dressing significantly increases the efficacy of the procedure and also increases the incidence and severity of some acute inflammatory side effects of PDT.