Preclinical evaluation of 3-18F-Fluoro-2,2-dimethylpropionic acid as an imaging agent for tumor detection

Witney, T. H. et al. (2014) Preclinical evaluation of 3-18F-Fluoro-2,2-dimethylpropionic acid as an imaging agent for tumor detection. Journal of Nuclear Medicine, 55(9), pp. 1506-1512. (doi: 10.2967/jnumed.114.140343)

Abstract

Deregulated cellular metabolism is a hallmark of many cancers. In addition to increased glycolytic flux, exploited for cancer imaging with 18F-FDG, tumor cells display aberrant lipid metabolism. Pivalic acid is a short-chain, branched carboxylic acid used to increase oral bioavailability of prodrugs. After prodrug hydrolysis, pivalic acid undergoes intracellular metabolism via the fatty acid oxidation pathway. We have designed a new probe, 3-18F-fluoro-2,2-dimethylpropionic acid, also called 18F-fluoro-pivalic acid (18F-FPIA), for the imaging of aberrant lipid metabolism and cancer detection. Methods: Cell intrinsic uptake of 18F-FPIA was measured in murine EMT6 breast adenocarcinoma cells. In vivo dynamic imaging, time course biodistribution, and radiotracer stability testing were performed. 18F-FPIA tumor retention was further compared in vivo to 18F-FDG uptake in several xenograft models and inflammatory tissue. Results: 18F-FPIA rapidly accumulated in EMT6 breast cancer cells, with retention of intracellular radioactivity predicted to occur via a putative 18F-FPIA carnitine-ester. The radiotracer was metabolically stable to degradation in mice. In vivo imaging of implanted EMT6 murine and BT474 human breast adenocarcinoma cells by 18F-FPIA PET showed rapid and extensive tumor localization, reaching 9.1% ± 0.5% and 7.6% ± 1.2% injected dose/g, respectively, at 60 min after injection. Substantial uptake in the cortex of the kidney was seen, with clearance primarily via urinary excretion. Regarding diagnostic utility, uptake of 18F-FPIA was comparable to that of 18F-FDG in EMT6 tumors but superior in the DU145 human prostate cancer model (54% higher uptake; P = 0.002). Furthermore, compared with 18F-FDG, 18F-FPIA had lower normal-brain uptake resulting in a superior tumor-to-brain ratio (2.5 vs. 1.3 in subcutaneously implanted U87 human glioma tumors; P = 0.001), predicting higher contrast for brain cancer imaging. Both radiotracers showed increased localization in inflammatory tissue. Conclusion: 18F-FPIA shows promise as an imaging agent for cancer detection and warrants further investigation.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Gottlieb, Professor Eyal and Schug, Dr Zachary
• Authors: Witney, T. H., Pisaneschi, F., Alam, I. S., Trousil, S., Kaliszczak, M., Twyman, F., Brickute, D., Nguyen, Q.-D., Schug, Z., Gottlieb, E., and Aboagye, E. O.
• College/School: College of Medical Veterinary and Life Sciences > School of Cancer Sciences
• Journal Name: Journal of Nuclear Medicine
• Publisher: Society of Nuclear Medicine and Molecular Imaging
• ISSN: 0161-5505
• ISSN (Online): 2159-662X