A Bridge not too Far: Personalized Medicine with the use of Theragnostic Radiopharmaceuticals

This article deals primarily with the selection criteria, production,and the nuclear, physical, and chemical properties of certaindual-purpose radionuclides, including those that are currentlybeing used, or studied and evaluated, and those that warrantfuture investigations. Various scientific and practical issuesrelated to the production and availability of these radionuclidesis briefly addressed. At brookhaven national laboratory (BNL),we have developed a paradigm that involves specific individual�dual-purpose� radionuclides or radionuclide pairs with emissionssuitable for both imaging and therapy, and which whenmolecularly (selectively) targeted using appropriate carriers,would allow pre-therapy low-dose imaging plus higher-dosetherapy in the same patient. We have made an attempt to sortout and organize a number of such theragnostic radionuclidesand radionuclide pairs that may thus potentially bring us closerto the age-long dream of personalized medicine for performingtailored low-dose molecular imaging (SPECT/CT or PET/CT)to provide the necessary pretherapy information onbiodistribution, dosimetry, the limiting or critical organ or tissue,and the maximum tolerated dose (MTD), etc., followed byperforming higher-dose targeted molecular therapy in the samepatient with the same radiopharmaceutical. As an example, ourpreclinical and clinical studies with the theragnostic radionuclideSn-117m are covered in somewhat greater detail.A troublesome problem that remains yet to be fully resolvedis the lack of availability, in sufficient quantities and at reasonablecost, of a majority of the best candidate theragnosticradionuclides in a no-carrier-added (NCA) form. In this regard,a summary description of recently developed new or modifiedmethods at BNL for the production of five theragnosticradionuclide/radionuclide pair items, whose nuclear, physical,and chemical characteristics seem to show promise fortherapeutic oncology and for treating other disorders thatrespond to radionuclide therapy, is provided.