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Updated: Apr 18, 2026

Microwave-assisted One-pot Synthesis of N-succinimidyl-4-[18F]fluorobenzoate [18F]SFB
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Microwave-assisted One-pot Synthesis of N-succinimidyl-4-[18F]fluorobenzoate [18F]SFB

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Rerouting the metabolic pathway of (18)F-labeled peptides: the influence of prosthetic groups

Susan Richter1, Melinda Wuest, Cody N Bergman

  • 1Department of Oncology, University of Alberta, Cross Cancer Institute , 11560 University Avenue, Edmonton, Alberta T6G 2X4, Canada.

Bioconjugate Chemistry
|January 10, 2015
PubMed

Insights

Switching the prosthetic group for (18)F-labeled bombesin derivatives from [(18)F]SFB to [(18)F]FDG improved tumor uptake and renal clearance. This modification enhances the potential of these peptides for targeted cancer imaging and therapy.

Area of Science:

  • Radiochemistry and Nuclear Medicine
  • Oncology
  • Molecular Imaging

Background:

  • Translational cancer research focuses on peptide ligands targeting overexpressed neuropeptide receptors.
  • Radiolabeled peptides are crucial for molecular imaging and therapy, requiring high tumor-to-background ratios and favorable pharmacokinetics.
  • Bombesin derivatives are potent ligands for targeting gastrin-releasing peptide (GRP) receptor-expressing prostate cancer.

Purpose of the Study:

  • To investigate the impact of switching the prosthetic group from N-succinimidyl-4-[(18)F]fluorobenzoate ([(18)F]SFB) to 2-deoxy-2-[(18)F]fluoro-d-glucose ([(18)F]FDG) on the metabolic pathway and pharmacokinetic profile of an (18)F-labeled bombesin derivative.
  • To evaluate the suitability of [(18)F]FDG-labeled bombesin derivatives for targeted prostate cancer imaging and therapy.

Main Methods:

  • Radiosynthesis of (18)F-labeled bombesin analogues [(18)F]FBz-Ava-BBN2 and [(18)F]FDG-AOAc-BBN2.
  • Assessment of binding affinity and inhibitory potency of nonradioactive analogues FBz-Ava-BBN2 and FDG-AOAc-BBN2 in PC3 cells.
  • Dynamic small animal PET imaging in PC3 mouse xenografts to investigate the influence of prosthetic groups on tumor uptake, clearance, and biodistribution.

Main Results:

  • Both [(18)F]FBz-Ava-BBN2 and [(18)F]FDG-AOAc-BBN2 were synthesized in good radiochemical yields (~50%) with high specific activity (>40 GBq/μmol).
  • Nonradioactive analogues demonstrated high inhibitory potency (IC50 values of 9 and 16 nM).
  • The switch to [(18)F]FDG significantly increased total tumor uptake (doubled) and renal elimination compared to [(18)F]FBz-Ava-BBN2, while blood clearance and metabolic stability remained similar.

Conclusions:

  • The substitution of [(18)F]SFB with [(18)F]FDG reduced lipophilicity, leading to improved renal clearance and enhanced tumor uptake of the (18)F-labeled bombesin derivative.
  • The single-step radiolabeling-glycosylation approach offers an innovative strategy for site-directed peptide labeling with (18)F.
  • The [(18)F]FDG-labeled bombesin derivative exhibits a favorable pharmacokinetic profile for targeted cancer molecular imaging and therapy.

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