title: Radiolabeled somatostatin analogs in prostate cancer.
abstract: Vapreotide (RC-160), a somatostatin analog, was labeled with 99mTC by a direct method and also by using CPTA [1,4,8,11-tetraazacyclotetradecane] as a bifunctional chelating agent. The labeled compounds were evaluated in nude mice bearing experimental human prostate cancers. In these studies, 111In-DTPA-D-Phe-Octreotide (111In-DTPA-octreotide) served as a standard and 99mTc-oxytocin as a receptor-non-specific control. 99mTc-octreotide was also used. The 24 htumor uptake of 99mTc-RC-160 was nearly 400% higher, (p < 0.05), than that of 111In-DTPA-octreotide and diminished upon receptor blocking. In all tissues except the kidneys, the uptake of 99mTc-RC-160 was also higher than that of 111In-DTPA-octreotide. The uptake of 99mTc-RC-160 was influenced by the amount of peptide injected and the best tumor/muscle and tumor/blood ratios were obtained when only one micrograms of the peptide (200 Ci/mmol) was administered.
authors.affiliation: Department of Radiology, Thomas Jefferson University Hospital, Philadelphia, PA 19107, USA. thakur1@jeflin.edu.tju
authors.forename: M L
authors.initials: ML
authors.lastname: Thakur
authors.forename: H
authors.initials: H
authors.lastname: Kolan
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: R
authors.initials: R
authors.lastname: Wiaderkiewicz
authors.forename: V R
authors.initials: VR
authors.lastname: Pallela
authors.forename: R
authors.initials: R
authors.lastname: Duggaraju
authors.forename: A V
authors.initials: AV
authors.lastname: Schally
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000493:pharmacokinetics*; D018931:Antineoplastic Agents, Hormonal / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D015282:Octreotide / Q000493:pharmacokinetics; D010121:Oxytocin / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism; D011877:Radionuclide Imaging; D017481:Receptors, Somatostatin / Q000378:metabolism; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D017556:Technetium Compounds / Q000493:pharmacokinetics; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D018931:Antineoplastic Agents, Hormonal; D017481:Receptors, Somatostatin; D017556:Technetium Compounds; C051458:vapreotide; D010121:Oxytocin; D013004:Somatostatin; D015282:Octreotide