[64Cu-NOTA-8-Aoc-BBN(7-14)NH2] targeting vector for positron-emission tomography imaging of gastrin-releasing peptide receptor-expressing tissues

Adam F. Prasanphanich, Prasant K. Nanda, Tammy L. Rold, Lixin Ma, Michael R. Lewis, Jered C. Garrison, Timothy J. Hoffman, Gary L. Sieckman, Said D. Figueroa, Charles J. Smith

Research output: Contribution to journalArticle

192 Scopus citations

Abstract

Radiolabeled peptides hold promise as diagnostic/therapeutic targeting vectors for specific human cancers. We report the design and development of a targeting vector, [64Cu-NOTA-8-Aoc-BBN(7-14)NH2] (NOTA = 1,4,7-triazacyclononane-1,4,7-triacetic acid, 8-Aoc = 8-aminooctanoic acid, and BBN = bombesin), having very high selectivity and affinity for the gastrin-releasing peptide receptor (GRPr). GRPrs are expressed on a variety of human cancers, including breast, lung, pancreatic, and prostate, making this a viable approach toward site-directed localization or therapy of these human diseases. In this study, [NOTA-X-BBN(7-14)NH2] conjugates were synthesized, where X = a specific pharmacokinetic modifier. The IC50 of [NOTA-8-Aoc-BBN(7-14)NH2] was determined by a competitive displacement cell-binding assay in PC-3 human prostate cancer cells using 125I-[Tyr4]-BBN as the displacement ligand. An IC 50 of 3.1 ± 0.5 nM was obtained, demonstrating high binding affinity of [NOTA-8-Aoc-BBN] for the GRPr. [64Cu-NOTA-X-BBN] conjugates were prepared by the reaction of 64CuCl2 with peptides in buffered aqueous solution. In vivo studies of [64Cu-NOTA- 8-Aoc-BBN(7-14)NH2] in tumor-bearing PC-3 mouse models indicated very high affinity of conjugate for the GRPr. Uptake of conjugate in tumor was 3.58 ± 0.70% injected dose (ID) per g at 1 h postintravenous injection (p.i.). Minimal accumulation of radioactivity in liver tissue (1.58 ± 0.40% ID per g, 1 h p.i.) is indicative of rapid renal-urinary excretion and suggests very high in vivo kinetic stability of [64Cu-NOTA-8-Aoc-BBN(7-14) NH2] with little or no in vivo dissociation of 64Cu 2+ from the NOTA chelator. Kidney accumulation at 1 h p.i. was 3.79 ± 1.09% ID per g. Molecular imaging studies in GRPr-expressing tumor models produced high-contrast, high-quality micro-positron-emission tomography images.

Original languageEnglish (US)
Pages (from-to)12462-12467
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume104
Issue number30
DOIs
StatePublished - Jul 24 2007

Keywords

  • Bombesin
  • Copper 64
  • Molecular imaging
  • PC-3 tumors

ASJC Scopus subject areas

  • General

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