PHOTODYNAMIC THERAPY OF PIGMENTED CHOROIDAL MELANOMAS

Purpose. To evaluate the effectiveness of photodynamic therapy with ch loroaluminum sulfonated phthalocyanine in the treatment of pigmented c horoidal melanomas in a rabbit model. Methods. Pigment containing B16F 10 murine melanoma cells were implanted transclerally into the subchor oidal space of 28 immunosuppressed New Zealand albino rabbits. The ani mals were treated with daily injections of cyclosporine and were follo wed up until tumors at least 2 mm in height were detected by ultrasono graphy. Twenty-four hours after the intravenous injection of chloroalu minum sulfonated phthalocyanine (CASPc, 5 mg/kg), tumors were irradiat ed at 675 nm through an argon-pumped dye laser at estimated total ligh t doses of 25 to 70 J/cm(2). Control animals were treated with light o nly or photosensitizer only. The animals were followed up for 4 1/2 to 8 weeks with regular fundus examinations. Results. Twenty tumor-beari ng rabbits were treated with light and dye. The tumor regressed in 12 animals. Five of these animals were followed up for at least 4 1/2 wee ks and the other seven for 8 weeks after treatment. At light doses und er 40 J/cm(2), tumor regrowth was observed in five animals within 10 d ays of treatment. In all central groups, the tumor-bearing eyes were f illed with tumor cells by the third week after implantation. Histologi c examination of tumors treated with photosensitizer and light reveale d prominent vascular damage early after treatment that resulted in vas cular occlusion. Tumor necrosis was evident within 24 hours of treatme nt. Conclusions. Results suggest that photodynamic therapy may have a role in the treatment of pigmented choroidal melanomas.