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Evaluation of deuterated 18F- and 11C-labeled choline analogs for cancer detection by positron emission tomography.

AbstractPURPOSE:
(11)C-Choline-positron emission tomography (PET) has been exploited to detect the aberrant choline metabolism in tumors. Radiolabeled choline uptake within the imaging time is primarily a function of transport, phosphorylation, and oxidation. Rapid choline oxidation, however, complicates interpretation of PET data. In this study, we investigated the biologic basis of the oxidation of deuterated choline analogs and assessed their specificity in human tumor xenografts.
EXPERIMENTAL DESIGN:
(11)C-Choline, (11)C-methyl-[1,2-(2)H(4)]-choline ((11)C-D4-choline), and (18)F-D4-choline were synthesized to permit comparison. Biodistribution, metabolism, small-animal PET studies, and kinetic analysis of tracer uptake were carried out in human colon HCT116 xenograft-bearing mice.
RESULTS:
Oxidation of choline analogs to betaine was highest with (11)C-choline, with reduced oxidation observed with (11)C-D4-choline and substantially reduced with (18)F-D4-choline, suggesting that both fluorination and deuteration were important for tracer metabolism. Although all tracers were converted intracellularly to labeled phosphocholine (specific signal), the higher rate constants for intracellular retention (K(i) and k(3)) of (11)C-choline and (11)C-D4-choline, compared with (18)F-D4-choline, were explained by the rapid conversion of the nonfluorinated tracers to betaine within HCT116 tumors. Imaging studies showed that the uptake of (18)F-D4-choline in three tumors with similar radiotracer delivery (K(1)) and choline kinase α expression-HCT116, A375, and PC3-M-were the same, suggesting that (18)F-D4-choline has utility for cancer detection irrespective of histologic type.
CONCLUSION:
We have shown here that both deuteration and fluorination combine to provide protection against choline oxidation in vivo. (18)F-D4-choline showed the highest selectivity for phosphorylation and warrants clinical evaluation.
AuthorsTimothy H Witney, Israt S Alam, David R Turton, Graham Smith, Laurence Carroll, Diana Brickute, Frazer J Twyman, Quang-Dé Nguyen, Giampaolo Tomasi, Ramla O Awais, Eric O Aboagye
JournalClinical cancer research : an official journal of the American Association for Cancer Research (Clin Cancer Res) Vol. 18 Issue 4 Pg. 1063-72 (Feb 15 2012) ISSN: 1557-3265 [Electronic] United States
PMID22235095 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Copyright©2012 AACR.
Chemical References
  • Carbon Radioisotopes
  • Radioactive Tracers
  • Fluorodeoxyglucose F18
  • Deuterium
  • Choline
Topics
  • Animals
  • Carbon Radioisotopes
  • Cell Line, Tumor
  • Choline (analogs & derivatives, metabolism)
  • Deuterium
  • Disease Models, Animal
  • Fluorodeoxyglucose F18
  • Humans
  • Kidney (metabolism)
  • Kinetics
  • Male
  • Melanoma (diagnostic imaging, metabolism)
  • Mice
  • Mice, Inbred BALB C
  • Mice, Nude
  • Neoplasms (diagnostic imaging, metabolism)
  • Oxidation-Reduction
  • Positron-Emission Tomography
  • Prostatic Neoplasms (diagnostic imaging, metabolism)
  • Radioactive Tracers

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