High efficiency of benzoporphyrin derivative in the photodynamic therapy of pigmented malignant melanoma

Benzoporphyrin derivative monoacid ring A (verteporfin, BPD-MA) when intravenously injected (5.5 mu mol kg(-1)) to C57/BL6 mice bearing a subcutaneously transplanted B1 melanoma gave a maximal accumulation in the tumour within 1-3 h with recoveries of 1.84-1.96 mu mol kg(-1). Irradiation of BPD-MA-loaded melanoma with 690-nm light from a dye laser at 3 h and 9 h post injection induced tumour necrosis and delay of tumour growth of 28 and 14 days respectively. The response of the tumour to BPD-MA photosensitization was enhanced by pretreatment with 1064-nm light from a pulse-operated Nd:YAG laser, which caused a selective breakdown of melanosomes.