Abstract
Methyl aminolevulinate (MAL), an ester of aminolevulinic acid, has been used effectively as a topical photosensitizing agent in the photodynamic therapy (PDT) of epidermal lesions such as actinic keratosis (AK) and basal cell carcinoma (BCC).
The optimal regimen for MAL-PDT (as used in all clinical trials) is MAL 160 mg/g applied for 3 hours before illumination with red light (570-670nm) at a total light dose of 75 J/cm(2), as determined in dose-finding trials.
In randomized, multicenter, phase III clinical trials, treatment with MAL-PDT resulted in a complete response (i.e. complete disappearance) in up to 91% of AK lesions and up to 97% of BCC lesions. With regard to lesion response rates, MAL-PDT was superior to placebo-PDT (in AK or BCC), and at least as effective as cryotherapy (in AK or BCC) or excision surgery (in BCC).
Cosmetic outcome with MAL-PDT was excellent to good in the vast majority of patients, and was judged by investigators to be better than with cryotherapy (in AK or BCC) or surgery (in BCC).
Over 75% of BCC lesions treated with MAL-PDT, including difficult-to-treat BCC, were still in remission 12-24 months after the last treatment.
MAL-PDT was generally well tolerated in clinical trials. The most frequently reported adverse events were local phototoxicity reactions, most of which were of mild to moderate intensity, resolved rapidly and were rarely treatment limiting.