Automated Production of [18F]Fluoroglutamine for Tumor Imaging

Authors

• X Zhang
• F Bhattacharyya
• Z Shi
• O Vasalatiy
• B Xu
• G Griffiths
• P Choyke
• R Swenson

Abstract

Glutaminolysis is an alternative source of metabolic energy for tumor cells. Therefore, glutamine (Gln) and its analogues may serve as potential imaging agents for tumor diagnosis using positron emission tomography (PET), especially for tumors with negative [18F]FDG scan. Recently, the radiosynthesis and in vivo evaluation of [18F]fluoroglutamine ([18F]FGln) was reported, which displayed highly selective and reproducible binding to tumor cells. However, the radiochemical yield was as low as 8-10%, and to date there is no automated synthesis published. In this approach, we have developed the optimized radiosynthesis of [18F]FGln on a fully automated system. Starting from the tosylate precursor, the radiosynthesis was carried out on GE FX-N Pro in 6 steps: 18F catch and release, azeotropic drying, fluorination reaction, purification, hydrolysis, and tracer formulation. To better purify the reaction intermediate, an HPLC process was performed to replace the solid-phase-extraction of the reported procedure, which greatly increased the chemical purity and radiochemical yield. As a result, [18F]FGln was radiosynthesized by a fully automated procedure in 17-25% yield (uncorrected, n > 10). This optimized automation will allow the routine supply of [18F]FGln in high chemical purity, radiochemical yield, and reproducibility; meanwhile radiation exposure to the radiochemists was greatly reduced.

Scientific Focus Area: Research Support Services

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