Aluminium phthalocyanine mediated photodynamic therapy in experimental malignant glioma

The efficacy of aluminium tetrasulfonated phthalocyanine (AISPc) as a photosensitizer for photodynamic therapy (PDT) was investigated in the C6 glioma model in Wistar rats. The depth and extent of tumour necrosis was dependent on both the dosage of intravenously (IV) administered AISPc, and the dose and time post-sensitization of 675 nm light administration. There was no effect on tumour or normal brain if the sensitizer dose was less than 0.5 mg/kg. Selective necrosis of tumour was evident 6 hours post-sensitization at an AISPc dose up to 1 mg/kg and light doses up to 200 J/cm(2). Necrosis occurred in normal brain at higher doses of light and sensitizer. There was no photosensitizer effect in animals treated 24 hours post AISPc administration. The ability of AISPc to act as a selective photosensitizer causing photonecrosis provides a basis for the generation of modified AISPc species as future agents in the PDT of brain tumours, especially as these sensitizers absorb light at a higher wavelength than those that are currently available.