CHAPTER 15: Methyl-Aminolevulinate/Aminolevulinic Acid Photodynamic Therapy: State of the Art in Dermatology and Possible Developments

After more than 25 years having passed since the first clinical report, photodynamic therapy (PDT) with topical aminolevulinic acid (ALA) or its methyl ester (methyl-aminolevulinate [MAL]) has been demonstrated to be highly effective and safe, with many therapeutic advantages over other treatment options in the treatment of actinic keratosis—particularly for multiple lesions with a cancerisation field—or Bowen's disease, and also to represent a valuable treatment option for basal cell carcinoma. However, it is still regarded as a “novel” therapy and its use is limited to selected dermatological patients, mainly because of the high cost of the approved MAL/ALA preparations and the lack of reimbursement of the drug and the procedure in many European countries and the USA. In addition, MAL/ALA PDT has been demonstrated to be useful for the treatment of other oncologic, inflammatory and infectious diseases, but it has—up to now—not raised enough interest from drug companies to fund trials for its approval by regulatory authorities.