Compounds used in photodynamic therapy with selectivity for tumour tissue and their potential for poritron emission tomography (PET)

Porphyrins and phthalocyanines are among the most potent classes of compounds used for photodynamic therapy of malignancies. Furthermore, several such compounds have been found to possess high tumour/healthy tissue ratios. In particular, this behavior see sms to be outspoken for brain tumours. Due to their chemical structure, these compounds are strong chelating agents, and their tumour localising ability does not seem to be hampered by the attachment of a metal ion into their center. . Practically no inf ormation about the use of porphyrins and phthalocyanines emerges from litterature. The objective of the present project is to perform the first chemical studies necessary in order to clearify if radiopharmaceuticals based on these structures may be develo ped. In the first phase of the project, simple labelling procedures using complexation with suitable radiometals (64-Cu, 68-Ga) will be tried out. For radiopharmaceuticals dedicated to clearify the behavior of brain malignancies, penetration of the blood/ brain barrier is essential. PET-relevant compounds with general affinity to brain malignancies are warranted, due to the insufficiencies of existing PET methods for such lesions. The present project, with a duration of two years, focusses on the necessar y radiochemical basis for this type of investigation, in particular automatisation of the radionuclide production, folowed by stability investigations. After this chemical work, the most promising compounds will be tested in a glioma rodent model, using t he animal PET scanner presently available and running at Rikshospitalet.