Deuterium and Fluorine-18 Labeled Glutamine – a PET Imaging Agent with Enhanced in Vivo Stability

Background

Accurate and comprehensive non-invasive imaging of cancer metabolism is crucial for diagnosis and monitoring. Among the various metabolic pathways exploited by cancer cells, glutamine metabolism plays a central role in supporting tumor growth and survival, serving as a major carbon and nitrogen source to support biosynthesis, redox homeostasis, and energy production. A wide range of cancers, including neuroblastoma, lymphoma, and renal carcinoma, exhibit a pronounced dependence on glutaminolysis as an alternative or complementary metabolic pathway. To exploit this vulnerability, several fluorine-18–labeled glutamine analogs have been developed for positron emission tomography (PET) imaging of tumor glutamine uptake. Despite their conceptual promise, the clinical utility of these tracers has been limited by a key technical challenge: many are susceptible to in vivo defluorination. This metabolic instability results in the release of free [18F]fluoride, which accumulates preferentially in bone and skull, generating high background signal and compromising tumor detection and delineation, particularly in anatomically complex regions.

Technology

Researchers at Stony Brook University have synthesized and examined deuterium and fluorine-18 dual isotope-labeled glutamine (4-[18F]FGln-d3) as a novel PET tracer for imaging the glutamine metabolism, particularly in cancer. The deuteration strategy enhances the in vivo metabolic stability of the agent by improving resistance to defluorination while maintaining tumor uptake in tumor-bearing rats. By minimizing defluorination and reducing problematic [18F]fluoride bone uptake, this technology offers a powerful tool for elucidating in vivo glutamine metabolism with enhanced image clarity for cancer diagnosis.