TY - JOUR T1 - Positron-emission Tomography (PET) Imaging Agents for Diagnosis of Human Prostate Cancer: Agonist <em>vs</em>. Antagonist Ligands JF - In Vivo JO - In Vivo SP - 583 LP - 592 VL - 26 IS - 4 AU - PRASANT K. NANDA AU - BRIEANNE E. WIENHOFF AU - TAMMY L. ROLD AU - GARY L. SIECKMAN AU - ASHLEY F. SZCZODROSKI AU - TIMOTHY J. HOFFMAN AU - BUCK E. ROGERS AU - CHARLES. J. SMITH Y1 - 2012/07/01 UR - http://iv.iiarjournals.org/content/26/4/583.abstract N2 - 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. ER -