The aim of this study is to investigate whether PD P 506 A-PDT is effective in treating mild to moderate AK lesions located on the head.

Actinic keratosis (AK) is a pre-cancerous skin abnormality usually caused by sun exposure. Actinic keratoses occur most commonly in fair skin, especially in the elderly. They mainly occur in sun-exposed skin areas like head and hands. It is standard of care to remove AK when diagnosed, which can be achieved by either physical ablation, chemotherapeutic agents or photodynamic therapy (PDT). A direct comparison versus placebo which is necessary for the exact quantification of the effect of PD P 506 A has not yet been performed and is subject of this study protocol.

Inclusion Criteria:

• Written informed consent
• Caucasian patients
• Diagnosis of actinic keratosis (AK) with at least three locally separated lesions located on head and/or face (hairless areas)
• Selected AK study lesions have clearly defined margins and are mild to moderate
• The distance between the study lesion borders is > 1.0 cm
• Maximum diameter of each study lesion is 1.8 cm
• Skin sun sensitivity type I to IV according to Fitzpatrick

Exclusion Criteria:

• PDT Non-responder
• Pre-treatment of the AK lesions eligible for study procedures with pharmaceuticals approved for the treatment of AK during the 4 weeks preceding PDT
• Pre-treatment of the AK lesions eligible for study procedures during the 2 weeks preceding PDT with keratolytic agents e.g. TCA, urea or salicylic acid containing formulations
• Pre-treatment with hypericin during the 2 weeks preceding PDT
• Treatment with systemic retinoids during the 3 months preceding PDT
• Treatment with cytostatics or radiation during the 3 months preceding PDT
• Female patients of childbearing potential
• Patients with clinically relevant suppression of the immune system
• Diagnosis of Porphyria
• Skin diseases that might interfere with response evaluation of study PDT
• Skin sun sensitivity type V or VI according to Fitzpatrick
• Known intolerance to one or more of the ingredients of the study medication
• Dementia or psychic condition that might interfere with the ability to understand the study and thus give a written informed consent
• Simultaneous participation in another clinical study or participation in another clinical study in the 30 days directly preceding inclusion
• Suspected lack of compliance