Photodynamic activity of liposome-delivered Cd-texaphyrin using tumor-bearing nude mice

Photodynamic effects in bladder-tumor bearing nude mice induced by a krypton ion laser (752.5 nm) after i.v. application of liposome-delivered cadmium texaphyrin were investigated. Cd-texaphyrin possesses strong absorption transitions in the far red spectral region (around 760 nm) and a high quantum efficiency of singlet oxygen production. No therapeutic effects were obtained using irradiation 24 hours after administration of the sensitizer, whereas phototreatment 2 hours after application led to significant tumor reduction. This corresponds well with studies on fluorophore-labeled liposomes indicating highest tumor accumulation 1-2 hours after administration. However, the induced cytotoxic effects were lower than those of HpD.