Abstract
Purpose: The aim of this study was development of an improved positron emission tomography (PET) radiotracer for measuring xC- activity with increased tumor uptake and reduced uptake in inflammatory cells compared to (S)-4-(3-18F-Fluoropropyl)-L-glutamic acid (18F-FSPG). Experimental design: A racemic glutamate derivative, 18F-hGTS13 was evaluated in cell culture and animal tumor models. 18F-hGTS13 was separated into C5-epimers and the corresponding 18F-hGTS13-isomer1 and 18F-hGTS13-isomer2 evaluated in H460 tumor bearing rats. Preliminary studies investigate the cellular uptake of 18F-hGTS13-isomer2 in multiple immune cell populations and states. Results: 18F-hGTS13 demonstrated excellent H460 tumor visualization with high tumor-to-background ratios, confirmed by ex vivo biodistribution studies. Tumor associated radioactivity of 18F-hGTS13 (7.5±0.9%ID/g, n = 3) was significantly higher than with 18F-FSPG (4.6±0.7%ID/g, n = 3, P = 0.01). 18F-hGTS13-isomer2 exhibited excellent H460 tumor visualization (6.3±1.1%ID/g, n-3), and significantly reduced uptake in multiple immune cell populations relative to 18F-FSPG. 18F-hGTS13-isomer2 exhibited increased liver uptake relative to 18F-FSPG (4.6±0.8%ID/g vs. 0.7±0.01%ID/g) limiting its application in hepatocellular carcinoma. Conclusion: 18F-hGTS13-isomer2 is a new PET radiotracer for molecular imaging of xC- activity which may provide information regarding tumor oxidation states. 18F-hGTS13-isomer2 has potential for clinical translation for imaging cancers of the thorax due to the low background signal in healthy tissue.
- Molecular Imaging
- Oncology: Lung
- PET
- 18F-hGTS13
- PET imaging
- cancer metabolism
- oxidative stress
- xC- transporter
- Copyright © 2019 by the Society of Nuclear Medicine and Molecular Imaging, Inc.