The study focuses on people whose immune system is weakened (immunosuppressed) and who have skin lesions caused by long‑term sun exposure, including rough, scaly patches known as actinic keratosis, a mild form of skin cancer called basal cell carcinoma, and a more aggressive type referred to as cutaneous squamous cell carcinoma. The treatment uses a specially formulated gel that contains the substance 5-aminolevulinic acid, identified in the trial by the code name BF-200 ALA (commercially Ameluz). After the gel is applied to the affected skin area, a controlled light source is used in a process called photodynamic therapy to activate the medication and target the abnormal cells.
The purpose of the trial is to evaluate how well the treatment works and how safe it is in the described patient group compared with people who are not immunosuppressed. Participants receive the gel, wait briefly for it to be absorbed, and then undergo the light‑based procedure. Follow‑up visits are scheduled a few months later to check whether the lesions have disappeared completely and to monitor for any new skin changes over the next year.



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