Photodynamic therapy (PDT) was the selective destruction of abnormal cells through light activation of a photosensitiser in the presence of oxygen. These cells accumulated more photosensitiser than normal cells. The photosensitiser generated reactive oxygen species upon illumination. For skin diseases, there had been an increasing interest in using precursors of the endogenous photosensitiser protoporphyrin IX (PpIX). The most commonly used precursors have been 5-aminolevulinic acid (ALA) and its derivatives. The present test drug, Metvix, contained the methyl ester of ALA, which penetrated the lesions well and shows high lesion selectivity. In vitro studies of animal and human tissues had shown significant intracellular formation of photoactive porphyrins after addition of Metvix. The increased photoactive porphyrins levels induced cytotoxic effects in tumour cells after photoactivation. The primary objective was to compare PDT with Metvix cream to PDT with placebo cream in terms of participants complete response rates based on histologically verified disappearance of the lesions at 6 months after last treatment cycle. Secondary objectives was to compare the two treatments in terms of histological and clinical mean participant response weighted by the number of lesions within a participant, lesion response rates across participants, clinical complete participant response, cosmetic outcome and adverse events.
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Number of Participants With Histologically Confirmed Complete Response
Timeframe: up to 9 months