⁶⁴Cu-Labeled Peptides for Tumor Visualization

Over the past decade, molecular imaging has revolutionized medical diagnostics especially the detection of cancer. Among this new frontier, positron emission tomography (PET) allows early diagnoses, efficient monitoring of therapeutic treatment, and quantitative imaging of cancer. One of the most attractive positron-emitting radionuclide is ⁶⁴Cu, which is meanwhile readily available in high specific activity from small cyclotrons. ⁶⁴Cu-labeled peptides represent very interesting vector molecules for certain entities of cancer.

Figure 1: Bifunctional chelating agents (BFCAs) for stable binding of copper radionuclides (arrows show the position of BFCAs for the linkage to peptides)

Pyridine-containing macrocyclic amine ligands I, bispidine II and cyclam tetrapropionic acid III derivatives (Fig. 1), which simultaneously allow the coupling to peptides, have been developed for the stable fixation of copper radionuclides.^[1-3] Corresponding bioconjugates with bombesin as well as neurotensin form rapidly very stable radiocopper complexes which permit clear visualization of tumor tissue in small animal PET studies.

Literature:

[1] G. Gasser, L. Tjioe, B. Graham, M.J. Belousoff, S. Juran, M. Walther, J.-U. Künstler, R. Bergmann, H. Stephan, L. Spiccia, Bioconjugate Chem. 2008, 19, 719-730. [2] S. Juran, M. Walther, H. Stephan, R. Bergmann, L. Steinbach, W. Kraus, F. Emmerling, P.Comba, Bioconjugate Chem. 2009, 20, 347-59. [3] A. Röhrich, R. Bergmann, A. Kretzschmann, S. Noll, J. Steinbach, J. Pietzsch, H. Stephan, 2010, submitted.