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ABSTRACTS
Year : 2009  |  Volume : 8  |  Issue : 4  |  Page : 229

Scientific Session 3: Neuroendocrine Tumours 1


Date of Web Publication1-Apr-2011

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How to cite this article:
. Scientific Session 3: Neuroendocrine Tumours 1. World J Nucl Med 2009;8:229

How to cite this URL:
. Scientific Session 3: Neuroendocrine Tumours 1. World J Nucl Med [serial online] 2009 [cited 2019 Aug 19];8:229. Available from: http://www.wjnm.org/text.asp?2009/8/4/229/78305

031

Chemical aspects of Y-90 and Lu-177 labelling of Octreotide analogs.


Renata Mikolajczak, Dariusz Pawlak

Research Department, Institute of Atomic Energy POLATOM Radioisotope Centre, Otwock, Poland

Several octreotide analogues radiolabelled with In-111, Y- 90, Lu-177, Ga-68, Tb-161 and Tc-99m involving various chelating approaches have been reported in recent years. Out of these the In-111 DTPA-octreotide (®Octreoscan, Covidien) remains a gold standard for Somatostatin Receptors Scintigraphy (SRS). The new SPECT agent, 99mTc labeled analog of octreotide, 99mTc-HYNICoctreotide (Tc-99m HYNIC-TOC, ®Tektrotyd, Polatom) has been granted Marketing Authorization for SRS in the last period as well. In addition, there is a growing interest for 68Ga-labelled octreotide analogues for PET, utilizing DOTA as chelator for Ga.68 DOTA-derivatised octreotides are playing predominant role in targeted radioimmunotherapy of neuroendocrine tumors with the use of betaemitting radionuclides like Y-90 or Lu-177, hence either SPECT or PET diagnosis is important for staging, patient qualification to therapy and therapy follow up. In preparation of therapeutic doses, the highest labeling yield, radiochemical purity and specific activity are the goals to be achieved when developing labeling strategies in order to deliver the highest radiation does to the tumor and at the same time sparing the adjacent tissue. On the other hand the diagnostic value of the new receptor specific agents and the therapeutic efficacy of the receptor mediated therapy are strongly enhanced by specific activity of the labeled molecule. Chelators providing stable complexes with radiometals suitable for therapy usually have high stability constants for other metals as well. Therefore aspects such as radionuclide production mode, the arising specific activity of the radionuclide and the accompanying radionuclide and chemical impurities have to be considered. At lower specific activities of radiometal larger amounts of peptide are necessary to obtain satisfactory radiolabelling yield, these high concentrations of peptide increase the risk of receptor saturation in vivo. Additionally, reagents and materials used in the production process and in the labeling reaction itself can be a source of chemical contaminants, which may compete with radiometal in complex formation. Usually therapeutic doses are prepared at high radioactive concentrations, when radiolysis is affecting their stability; therefore the addition of free-radical scavengers is advisable. The optimal labeling conditions therefore are not only limited to the selection of a proper buffer, pH and incubation parameters, but require detailed knowledge about the chemical composition of the radionuclide solution and the peptide-chelator system.

References:

  1. W.A.P. Breeman, M. de Jong, T.J.Visser, J.L. Erion, E.P. Krenning: Optimising conditions for radiolabelling of DOTA-peptides with 90Y, 111In and 177Lu at high specific activities, Eur J Nucl med Mol Imaging 2003;30:917-920
  2. D.Pawlak, A. Korsak, R. Mikolajczak, B. Janota, U. Karczmarczyk, E. Jakubowska: Preclinical evaluation of therapeutic radiopharmaceuticals based on 90Y and 177Lu. In IAEA-TRS 458 Comparative evaluation of therapeutic radiopharmaceuticals, IAEA Vienna 2007: 217-232
  3. S.Jurrison, C.Cutler, S.V.Smith: Radiometal complexes characterization and relevant in vitro studies. QJ Nucl Med Mol Imaging 2008;52:222-34
032

The Targeting of G-protein Coupled Receptors with Radiopeptides for Imaging and Internal Radionuclide Therapy.


Prof. H. R. Maecke,

Division of Radiological Chemistry, University Hospital Basel, Petersgraben 4, CH-4031 Basel, Switzerland

No abstract available

033

An update on our experience with Peptide Receptor Radiotherapy (PRRT) in Neuroendocrine Tumours (NETs)


Prof. R.P. Baum.

Dept. of Nuclear Medicine, Center for PET/CT, Zentralklinik Bad Berka, Bad Berka, Germany

No abstract available

034

Lanreotide-based Diagnosis and Treatment of Cancer Patients: Current Status, Indications, Future Directions"


Prof. Roy Moncayo, University of Innsbruck, Austria

No abstract available






 

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