66Ga: A Novelty or a Valuable Preclinical Screening Tool for the Design of Targeted Radiopharmaceuticals?

Alejandro Amor-Coarasa, James M. Kelly, Shashikanth Ponnala, Anastasia Nikolopoulou, Clarence Williams, John W. Babich

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Emerging interest in extending the plasma half-life of small molecule radioligands warrants a consideration of the appropriate radionuclide for PET imaging at longer time points (>8 h). Among candidate positron-emitting radionuclides, 66Ga (t1/2 = 9.5 h,β+ = 57%) has suitable nuclear and chemical properties for the labeling and PET imaging of radioligands of this profile. We investigated the value of 66Ga to preclinical screening and the evaluation of albumin-binding PSMA-targeting small molecules. 66Ga was produced by irradiation of a natZn target. 66Ga3+ ions were separated from Zn2+ ions by an optimized UTEVA anion exchange column that retained 99.99987% of Zn2+ ions and allowed 90.2 ± 2.8% recovery of 66Ga3+. Three ligands were radiolabeled in 46.4 ± 20.5%; radiochemical yield and >90% radiochemical purity. Molar activity was 632 ± 380 MBq/mol. Uptake in the tumor and kidneys at 1, 3, 6, and 24 h p.i. was determined by μPET/CT imaging and more completely predicted the distribution kinetics than uptake of the [66Ga]Ga-labeled ligands did. Although there are multiple challenges to the use of 66Ga for clinical PET imaging, it can be a valuable research tool for ligand screening and preclinical imaging beyond 24 h.

Original languageEnglish (US)
Article number2575
JournalMolecules
Volume23
Issue number10
DOIs
Publication statusPublished - Oct 9 2018

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Keywords

  • Ga
  • PET imaging
  • Preclinical screening
  • Targeted radiotherapy

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemistry (miscellaneous)
  • Molecular Medicine
  • Pharmaceutical Science
  • Drug Discovery
  • Physical and Theoretical Chemistry
  • Organic Chemistry

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