Cisplatin-induced potentiation of the antitumor effect of photodynamic therapy

The effect of cisplatin on the effectiveness of photodynamic therapy (PDT) was experimentally studied using leukemia P-388 as a tumor growth model. Treatment was initiated in the presence of a disseminated tumor process. Photosens was administered once in dose of 5 mg/kg on day 5 of tumor growth; PDT was made 24 hours after administration of the sensitizer. Cisplatin was given once in a dose of 7 mg/kg 48, 24, 2, and 0.25 hours before PDT concurrently with the start of radiation or 0.25, 2 or 24 hours after it. A local antitumor effect was judged from the suppression of growth in a primary (irradiated) tumor focus; a systemic effect was from the increased lifespan of mice. The local effect of combination treatment during its all used regimens was higher than that of PDT or chemotherapy (CT) alone. The efficiency of systemic CT in during combination treatment versus its individual components was increased only when the cytostatic was injected prior to PDT.

photodynamic therapy, cisplatin