Selective photodynamic effects of the new photosensitizer ATX-S10(Na) on choroidal neovascularization in monkeys

Abstract

Objective: To determine the optimal treatment variables for photodynamic therapy (PDT) with new photosensitizer ATX-S10(Na) (13,17-bis[1- carboxypropionyl] carbamoylethyl-8-etheny-2-hydroxy-3-hydroxyimino- ethylidene-2,7,12,18-tetranethyl 6 porphyrin sodium) to induce selective occlusion of choroidal neovascularization (CNV) in nonhuman primate eyes. Methods: Experimental CNV was induced in monkey eyes by laser photocoagulation, and PDT was performed in neovascularized and healthy eyes with different treatment variables. At 0 to 150 minutes after 4-, 8-, and 12- mg/kg of body weight intravenous injections of ATX-S10(Na), a diode laser was irradiated at the dose of I to 127 J/cm2 (wavelength, 670 nm). Vascular occlusion induced by PDT was evaluated using fluorescein angiography, indocyanine green angiography, and histological examination at 1 day to 4 weeks after irradiation. Results: Selective occlusion of CNV without damage to healthy retinal and choroidal capillaries was achieved in the following conditions: 30 to 74 J/cm2 irradiation at 30 to 74 minutes after the 8-mg/kg injection, and 1 to 29 J/cm2 irradiation at 30 to 74 minutes or 30 to 74 J/cm2 irradiation at 75 to 150 minutes after the 12-mg/kg dye injection. Regrowth of CNV often occurred when the retina was heavily injured by excessive PDT. Conclusion: By using optimal treatment variables, PDT using ATX-S10(Na) induces selective occlusion of CNV in nonhuman primate eyes, providing the possibility of therapeutic application to the clinical practice. Clinical Relevance: Occlusion of CNV without direct damage to the sensory retina is useful to preserve visual acuity in patients with exudative age-related macular degeneration. A clinical trial of PDT using ATX-S10(Na) is desirable.