Uridine-Based PET/NIRF Dual-Modality imaging for precision tumor diagnosis and surgery.

[PURPOSE] Metabolic reprogramming allows cancer cells to survive and proliferate under nutrient-deprived conditions. Uridine, a central molecule in pyrimidine metabolism, supports both nucleotide biosynthesis and redox homeostasis. However, high-sensitivity imaging tools for equilibrative nucleoside transporter 1 (ENT1)-mediated uridine transport are lacking, limiting applications in precise diagnosis and intraoperative guidance. This study aimed to develop and validate a novel dual-modality imaging platform targeting ENT1-mediated uridine transport for tumor imaging and surgical navigation.

[METHODS] We synthesized [Ga]Ga-DOTA-FZUD and ICG-FZUD probes for PET and NIR-II fluorescence imaging, respectively. Small-animal PET/CT and NIR-II fluorescence imaging were performed, and biodistribution were analyzed. Ex vivo NIR-II fluorescence imaging using ICG-FZUD was performed on surgical specimens from three gastric cancer patients to confirm tumor targeting.

[RESULTS]  [Ga]Ga-DOTA-FZUD exhibited excellent radiochemical purity. In pancreatic cancer models with relatively higher ENT1 expression (AsPC-1, Panc-1) compared with lower ENT1 expression models (MiaPaCa-2, BxPC-3), [Ga]Ga-DOTA-FZUD demonstrated markedly greater tumor uptake. Similar uptake was also observed in gastric, breast, and glioblastoma models, with tumor-to-muscle ratios consistently exceeding 3.5. ICG-FZUD enabled high-contrast NIR-II imaging and clearly delineated tumor margins. Notably, ICG-FZUD penetrated the blood-brain barrier and visualized orthotopic glioblastoma. Ex vivo imaging of human gastric cancer tissues confirmed selective tumor uptake, consistent with histopathological findings.

[CONCLUSION] This ENT1-targeted uridine transport PET/NIRF dual-modality imaging platform complements conventional glucose-based imaging and provides real-time intraoperative navigation. It holds significant promise for early cancer diagnosis and precision surgery with strong translational potential.