High folate receptor expression in gliomas can be detected

Area of Science:

• Oncology
• Radiochemistry
• Molecular Imaging

Background:

• Non-invasive imaging is crucial for cancer detection, especially in delicate organs like the brain.
• Folate receptors (FRs) are overexpressed in many tumor cells, making them targets for imaging and therapy.
• [18F]FOL, a folate analogue, shows preferential accumulation in FR-positive tumor cells.

Purpose of the Study:

• To investigate the ability of [18F]FOL to detect orthotopic gliomas in a rat model using PET.
• To study the expression of FRs in human glioblastoma samples for potential clinical relevance.

Main Methods:

• Orthotopic gliomas were induced in rats and imaged using PET/CT with [18F]FOL or [18F]FDG.
• Biodistribution studies, autoradiography, and immunostaining were performed on animal tissues.
• Human glioblastoma samples were analyzed for FR expression.

Main Results:

• [18F]FOL demonstrated a significantly increasing tumor-to-brain uptake ratio (TBR) in rat gliomas over time, reaching 5.7 ± 1.0 by day 32.
• [18F]FDG showed a consistently lower TBR (1.6 ± 0.1).
• Ex vivo autoradiography confirmed a high TBR for [18F]FOL (116.1 ± 26.9) compared to [18F]FDG (2.9 ± 0.6), correlating with increased FR-α expression in gliomas.

Conclusions:

• Upregulation of FR-α in glioma regions of both human and animal tissues provides a biochemical basis for [18F]FOL uptake.
• FR-targeting agents like [18F]FOL show potential for clinically relevant translation in glioma detection and treatment.