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discovered 02_2012

FOCUS// The HZDR Research Magazine WWW.Hzdr.DE 16 17 organism as DNA. Thus, the radioactively labeled single DNA strands don‘t get digested in the bloodstream and there is only one possible binding site in the entire organism: the one on the antibodies that have accumulated in the tumor tissue and that carry the complementary DNA strand.“ Radioactive twins The use of radioactive substances for targeting cancer cells for destruction holds yet another advantage: there exist, if you will, “twin partners“ (so-called radioisotopes) of suitable radio-metals used in therapeutic applications. Yttrium-86, the lighter twin of yttrium-90, can be used for PET imaging to show whether a specific antibody is accumulating in the tumor tissue of a given patient – with only a very low dose of radiation given off to healthy tissues. Only if the antibody does accumulate in the tumor tissue, the larger of the twins, the therapy nuclide (Y90) with the identical antibody attached is administered to effectively destroy the cancer cells in the body. “In the future, this theragnostic principle will allow us to personalize internal radiotherapy and to apply the active drug in only those patients in whom it attacks the tumor and not the normal tissues,“ says Jörg Steinbach, director of the Institute of Radiopharmacy. To give another example: copper-64 is used in research for future radiodiagnostics whereas copper-67 is considered a very good candidate therapeutic radionuclide. All of this is still a far cry from development of a custom- tailored internal radiation therapy approach that has been approved for patient use. What is also clear is that these new approaches have to be combined with today’s state-of-the-art anti-cancer treatment modalities such as modern-day radiochemotherapy. This requires the close collaboration between two medical disciplines: nuclear medicine for internal radiotherapy and radiation oncology for external beam radiotherapy, or radiochemotherapy. Thanks to a fortuitous collaboration at the OncoRay Center, Jörg Steinbach is convinced that Dresden is the ideal site for putting such innovative concepts on the map. However, even with these new exciting perspectives for cancer research and cancer care, prevention is by far the most effective strategy for reducing cancer deaths. Cancer specialists estimate that the risk of getting cancer during one‘s lifetime can be cut in half simply by a healthy lifestyle without smoking and without long periods of exposure to the sun, with plenty of exercise, a healthy diet, and alcohol in moderation. Most of us probably know this already and should really be making a conscious effort to put this awareness into practice. Literature C. Förster, R. Bergmann et al.: “Radiolabeled L-oligonucleotides with tunable pharmacokinetics – A suitable complementary system for pretargeting approaches,“ in Nuclear Medicine and Biology, vol. 706 (2010), 37/6 (DOI: 10.1016/j.nucmedbio.2010.04.100) Contact _ Institute of Radiopharmacy at HZDR As of January 2013: Institute of Radiopharmaceutical Cancer Research at HZDR Dr. Hans-Jürgen Pietzsch Prof. Jörg Steinbach NATURE AS THE MODEL: Artificial DNA strands allow for the quick and precise delivery of radionuclides to scattered tumor cells. A single DNA strand is attached to a tumor affine antibody, which is introduced into the patient’s body, followed by the complementary strand with the radionuclide attached. In the body, the two strands combine, binding each other firmly (right). Such a staggered approach ensures that the radionuclides destroy only the tumor cells while preserving healthy tissues. tumor cell