Current developments in single photon radiopharmaceuticals for tumor imaging

Development of peptides and amino acids labeled with single photon gamma em itters has promoted a large number of investigations in nuclear medicine es pecially for tumor imaging. Radiolabeled peptides have several advantages o ver antibodies mainly related to immunogenicity and size. Tumor localizatio n and total body clearance of peptides are more rapid compared to antibodie s. Recently, several somatostatin analogues labeled with Tc-99m have been s tudied by several different investigators. In-111 labeled lanreotide (Mauri tus) was reported to be highly successful in localization of neuroendocrine tumors. A synthetic amino acid, alpha methyl tyrosine labeled with I-123 w as shown to be transported to tumors by a carrier mediated system. Developm ent of a glucose analog labeled with a single photon emitting radionuclide and meeting the structural requirements for hexokinase reaction and phospho rylation have not yet been possible. However, it has been possible to synth esize chemically stable single photon glucose analogues interacting with gl ut(s), glucose transporters.