Positron-emission tomography (PET) imaging agents for diagnosis of human prostate cancer: Agonist vs. antagonist ligands

Prasant K. Nanda, Brieanne E. Wienhoff, Tammy L. Rold, Gary L. Sieckman, Ashley F. Szczodroski, Timothy J. Hoffman, Buck E. Rogers, Charles J. Smith

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Aim: The present study adds scientific support to the growing debate regarding the superiority of radiolabeled bombesin-based antagonist peptides over agonists for molecular imaging and therapy of human tumors overexpressing the gastrin-releasing peptide receptor (GRPR) and describes a detailed in vitro and in vivo comparison of 64Cu-NODAGA-6-Ahx-BBN(7-14)NH2 agonist and 64Cu-NODAGA-6-Ahx-DPhe6-BBN(6-13)NHEt antagonist ligands. Materials and Methods: Conjugates were synthesized by solid-phase peptide synthesis, purified by reversed-phase high-performance liquid chromatography, and characterized by electrospray ionization-mass spectroscopy. The conjugates were radiolabeled with 64Cu. Results: In vitro and in vivo data support the hypothesis for targeting of the GRPR by these tracer molecules. Maximum-intensity micro Positron Emission Tomography (microPET) imaging studies show the agonist ligand to provide high-quality, high-contrast images with very impressive tumor uptake and background clearance, with virtually no residual gastrointestinal or renal-urinary radioactivity. Conclusion: Based on microPET imaging experiments, we conclude the agonist peptide ligand to be a superior molecular imaging agent for targeting GRPR.

Original languageEnglish
Pages (from-to)583-592
Number of pages10
JournalIn Vivo
Volume26
Issue number4
StatePublished - 2012

Keywords

  • Agonist
  • Antagonist
  • Bombesin
  • Copper
  • MicroPET

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