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 language | English |
|---|---|
| Pages (from-to) | 583-592 |
| Number of pages | 10 |
| Journal | In Vivo |
| Volume | 26 |
| Issue number | 4 |
| State | Published - 2012 |
Keywords
- Agonist
- Antagonist
- Bombesin
- Copper
- MicroPET