Evaluation of topical photodynamic therapy of mammary carcinoma with an experimental gel containing liposomal hydroxyl-aluminium phthalocyanine.

BACKGROUND: Photodynamic therapy (PDT) is a clinically-accepted approach for the therapy of many types of cancer. This study focused on the treatment of mammarian carcinoma by topical administration of hydroxyl-aluminium phthalocyanine (AlOH-PC), compared to a clinically-approved photosensitizer (Metvix, Galderma & PhotoCure ASA, Inc., Oslo, Norway).

MATERIALS AND METHODS: MDA-MB 231 cells were subcutaneously injected into the right flank of athymic nude mice. Mice with grown tumours were used for in vivo efficacy studies. Different doses of liposomal AlOH-PC were applied to determine the most effective dose. In later studies, Metvix or our liposomal-AlOH-PC gel formula were used. Topical application of photosensitizers was followed by the PDT irradiation at 600-700 nm (635 nm peak). Tumour growth was measured three times weekly.

RESULTS: Therapeutic studies revealed that AlOH-PC treatment led to complete tumour remission in 90% (9/10) of experimental animals, whereas usage of the commercially available Metvix only postponed the tumour growth. Moreover, usage of liposomal AlOH-PC shortened the time allowed between the application of the photosensitizer and light exposure: for Metvix, hours are usually needed, while the tested liposomal AlOH-PC showed remarkable outcomes after only 10 min.

CONCLUSION: Liposomal AlOH-PC gel appears to be potentially suitable for PDT of mammarian carcinoma.