Title:Tetraamine-Coupled Peptides and Resulting 99mTc-Radioligands: An Effective Route for Receptor-Targeted Diagnostic Imaging of Human Tumors
Volume: 12
Issue: 23
Author(s): Berthold A. Nock and Theodosia Maina
Affiliation:
Keywords:
Tumor imaging, 99mTc-radiopeptide, acyclic tetraamine, receptor targeting
Abstract: The successful application of OctreoScan® ([111In-DTPA]octreotide) in the diagnosis of sst2-expressing neuroendocrine
tumors (NETs), on one hand, and the manifestation of peptide receptor targets in a wide range of human cancers,
on the other, have synergistically induced a booming emergence of numerous radiolabeled peptide (radiopeptide)
probes for tumor diagnosis and therapy in man. Definition of molecular targets and their relation to neoplastic disease has
preceded peptide-based radiopharmaceutical design and development. New criteria have been set to safeguard efficient
localization of radionuclides on tumor-associated high affinity – low capacity peptide receptor systems. New technical
and biological terms, such as specific activity or receptor affinity and internalization, have invaded the Radiopharmacy
domain and have irrevocably altered our concept of radiopharmaceutical design. Nonetheless, 99mTc remains the gold
standard of diagnostic nuclear medicine as a result of ideal nuclear characteristics, cost-effectiveness and wide availability
in high purity and high specific activity by means of commercial 99Mo/99mTc-generators. The evolution of conventional
99mTc-perfusion agents into modern state-of-the-art molecular radiopharmaceuticals has been a challenge addressed by
several researchers. The present review summarizes recent advances in the development of 99mTc-labeled peptides for in
vivo targeting of neoplastic disease, and, in particular, those functionalized with acyclic tetraamines. Conclusions on their
applicability in non-invasive diagnosis and staging of cancer patients are drawn.
