High-LET endoradiotherapy: in vivo studies with a metabolically-directed Auger emitting anticancer drug in a murine tumour model

Therapeutic studies with high specific activity 6-[125I]-iodo-MNDP (0.925-22.2 MBq) have demonstrated that this Auger-emitting drug is effective in treating mice with a transplanted CMT-93 rectal adenocarcinoma without incurring early or late radiation-associated sequelae. Its efficacy has been attributed to the selective intranuclear localization of 6-[125I]-iodo-MNDP metabolite and consequent high-LET quality toxicity in heterogeneously distributed tumour cells that exhibit specific onco-alkaline phosphatase isoenzyme activity. Quasi-microdosimetric estimations of the radiobiologically equivalent low-LET single fraction absorbed tumour dose are of an order of magnitude that might be associated with the permanent control of this tumour. (author)