ECR 2014: First-in-human glutamine PET trial results revealed

VIENNA—Preliminary data regarding the first known human trial involving glutamine PET for the detection of glioma showed encouraging pharmacokinetics and biodistribution, according to researchers presenting at this year’s European Congress of Radiology (ECR).

Glutamine is taken up by tumor cells as a source of energy and therefore the radionuclide and glutamine analog F-18 4-L-fluoroglutamine is an ideal biomarker for metabolic imaging of tumors. The current study is limited to neuroimaging of glioma, but the agent is also being researched for other cancers. Fluoroglutamine is set apart from other metabolic agents like FDG because it uses different metabolic pathways that can indicate high-grade tumor development and potential metastases.

Co-author of the study, Christina Pressl, MD, from the department of radiology at the Medical University of Vienna, presented the early-stage results showing no adverse effects. All five low-grade tumors that were included in the study were fluoroglutamine-PET negative, whereas the only high-grade lesion that was deemed suspicious of transformation by FDG PET also tested positive with fluoroglutamine-PET.

“To our knowledge this is the first in-human trial of a glutamine-analog imaging agent with PET/CT,” stated Pressl. “It shows fluoroglutamine’s eligibility for detecting high-grade glioma in human subjects and encourages further testing of fluoroglutamine as a much needed noninvasive biomarker for distinguishing high-grade gliomas from low-grade gliomas.”

Addicted to glutamine

Pressl noted glutamine as a prime research subject for oncologic imaging by outlining how voracious tumors become dependent on glutamine once they are high-grade and require anabolic pathways of metabolism. “Glutamine is a very important source for the tumor cell.”

For this reason, glutamine imaging has the potential to go beyond glioma imaging into other clinical applications. “We have just started investigating patients so the data isn’t ready to be presented quite yet,” Pressl told Molecular Imaging.

F-18 fluoroglutamine is not currently approved for clinical use and requires further study and regulatory approval before it can be made available for oncologic imaging.