title: Synthesis and preliminary evaluation of Tc-99m-labeled somatostatin analog (RC-160) using "3+1" mixed ligand approach.
abstract: The success of (111)In-pentetreotide as a cancer-imaging agent has given impetus to the search for other peptide-based radiopharmaceuticals. The labeling with Tc-99m has become even more attractive because of the ready availability and near ideal physical properties. Additionally, the kinetics of the peptide-receptor interactions favors the radiolabeling with technetium-99m. A somatostatin analog RC-160 has been labeled with Tc-99m using the "3+1" mixed ligand approach utilizing the NNS/S coordination sites. The ternary complex was formed in greater than 95% within 30 min by simultaneous reduction and complexation of technetium-99m pertechnetate. The Tc-99m and the surrogate rhenium complexes showed similar chromatographic behavior. The complex was evaluated by in vitro receptor binding studies carried out on HTB-121 breast cancer cell line and biodistribution studies performed in normal mice. Our findings suggest that RC-160 can be labeled by the mixed ligand approach with the complex retaining its biological activity and warrants further studies.
authors.affiliation: Cyclotron and Radiopharmaceutical Department, King Faisal Specialist Hospital and Research Centre, MBC-03, P.O. Box 3354, 11211, Riyadh, Saudi Arabia. Amarty@kfshrc.edu.sa
authors.forename: J K
authors.initials: JK
authors.lastname: Amartey
authors.forename: R S
authors.initials: RS
authors.lastname: Parhar
authors.forename: I
authors.initials: I
authors.lastname: Al-Jammaz
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism; D005260:Female; D006801:Humans; D008024:Ligands; D051379:Mice; D011869:Radioligand Assay; D019275:Radiopharmaceuticals / Q000138:chemical synthesis*; D013004:Somatostatin / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D017556:Technetium Compounds / Q000737:chemistry; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured / Q000378:metabolism
chemical_list: D008024:Ligands; D019275:Radiopharmaceuticals; D017556:Technetium Compounds; C051458:vapreotide; D013004:Somatostatin