Peptide Receptor Radionuclide Therapy: Preclinical Findings

Somatostatin is a cyclopeptide that has a broad inhibitory effect on the secretion of hormones such as growth hormone, glucagon, and insulin. The molecular basis of the use of radiolabeled octreotide in scintigraphy and radionuclide therapy is receptor-mediated internalization and cellular retention of the radionuclide. A large variety of radiolabeled somatostatin derivatives have been prepared for radionuclide therapy purposes and are in various stages of investigation. The chapter shows that radionuclide therapy with radiolabeled somatostatin analogs is a most promising new treatment modality for patients bearing sst₂-positive tumors. The molecular basis of the use of radiolabeled octreotide in scintigraphy and radionuclide therapy is receptor-mediated internalization and cellular retention of the radionuclide. Several reports have been published on the in vitro receptor binding to somatostatin receptors of another somatostatin analog, the octapeptide RC-160. In conclusion, radiolabeled peptides have opened a new era in nuclear oncology, not only for diagnosis but also for radionuclide therapy.