In Vivo Evaluation of a Bombesin Analogue Labeled with Ga-68 and Co-55/57

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Abstract

Purpose: The purpose of this study was to apply an analogue of bombesin, NOTA-AMBA, labeled with Co-55 or Ga-68, for preclinical imaging of prostate cancer. Procedures: The peptide NOTA-AMBA was labeled with Ga-68 or Co-55 by microwave irradiation. Biodistribution in xenograft mice (PC3) was performed at 1, 4, and 24 h (only cobalt at 24 h) using a fixed amount of peptide. Four weeks post-inoculation, xenograft mice were positron emission tomography/X-ray computed tomography scanned after tail vein injection of [ 68Ga]NOTA-AMBA or [ 55Co]NOTA-AMBA. Results: Labeling with Ga-68 and Co-55/57 was achieved in yields greater than 90 %. A radiochemical purity (RCP) of 95 and 90 % were obtained for Ga-68 and Co-55, respectively. Both radiopeptides showed high uptake in the intestines, stomach, pancreas, and in the tumor ([ 68Ga]NOTA-AMBA, 10.3 %ID/g at 1 h to 6.4 %ID/g at 4 h; [ 57Co]NOTA-AMBA, 8.2 %ID/g at 1 h to 5.3%ID/g at 24 h). Normal tissue cleared over time improving tumor-to-background ratios. Conclusions: NOTA-AMBA was labeled in high yields and RCP with Ga-68 and Co-55/57. High tumor uptake in a subcutaneous mouse prostate cancer model was observed. At 24 h, [ 55/57Co]NOTA-AMBA showed better tumor-to-organ ratios than [ 68Ga]NOTA-AMBA at both 1 and 4 h post-injection. Hence, for imaging, [ 55Co]NOTA-AMBA was found to be superior compared to [ 68Ga]NOTA-AMBA.

Original languageEnglish
JournalMolecular Imaging and Biology
Volume18
Issue number3
Pages (from-to)368-376
ISSN1536-1632
DOIs
Publication statusPublished - Jun 2016

Keywords

  • AMBA
  • Bombesin
  • Cobalt-55
  • Gallium-68
  • PET
  • Positron emission tomography
  • Prostate cancer
  • Cobalt Radioisotopes/chemistry
  • Humans
  • Male
  • Tomography, X-Ray Computed
  • Positron-Emission Tomography
  • Chromatography, High Pressure Liquid
  • Peptides/blood
  • Gallium Radioisotopes/chemistry
  • Tissue Distribution
  • Inhibitory Concentration 50
  • Bombesin/analogs & derivatives
  • Protein Stability
  • Binding, Competitive
  • Radiopharmaceuticals/chemistry
  • Mice, SCID
  • Xenograft Model Antitumor Assays
  • Animals
  • Cell Line, Tumor

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