Influence of drug and light dose in determining PDT efficacy in human pancreatic cancer cells treated with zinc tetrasulfonated phthalocyanines (ZnTSPc)

Abstract

Photodynamic therapy (PDT) has the potential to be applied as an adjuvant treatment modality in advanced cancer cases and recently its role in the management of pancreatic cancer, has been evaluated. Nevertheless PDT remains an experimental therapy and one of the main reasons is its complexity, as far as it relies on the combined action of the photosensitizing drug and light source. In this study was evaluated the effect of various photosensitizer and photoirradiation doses, in the lethality of MIA PaCa cell line by using ZnPcS<SUB>4</SUB> as photosensitizer and a novel diode laser system as illumination source. No lethality was observed when only laser light or only photosensitizer was applied to cells. Cells treated with various concentrations of ZnTSPc and a light dose of 9 J/cm<SUP>2</SUP> indicated more than 70% lethality, 24 hrs after irradiation and with a light dose of 6 J/cm<SUP>2</SUP> presented almost 90% lethality, 72 hours after irradiation. The results show that low light and photosensitizer (drug) doses are enough to obtain lethality of more than 90% of MIA PaCa cells.