Synthesis and Ex Vivo Autoradiographic Evaluation of Ethyl-β-d-galactopyranosyl-(1,4′)-2′-deoxy-2′-[18F]fluoro-β-d-glucopyranoside—A Novel Radioligand for Lactose-Binding Protein: Implications for Early Detection of Pancreatic Carcinomas with PET

Introduction Previous studies demonstrated that the lactose-binding protein (hepatocellular carcinoma–intestine–pancreas and pancreatitis-associated proteins (HIP/PAP)) is upregulated >130 times in peritumoral pancreatic tissue as compared to normal pancreatic tissue. Therefore, we developed a new radiolabeled ligand of HIP/PAP, the ethyl- β - d -galactopyranosyl-(1,4′)-2′-deoxy-2′-[ 18 F]fluoro- β - d -glucopyranoside (Et-[ 18 F]FDL) for noninvasive imaging of pancreatic carcinoma using positron emission tomography and computerized tomography (PET/CT). Methods The novel precursor and radiolabeling methods for synthesis of Et-[ 18 F]FDL produced no isomers; the average decay-corrected radiochemical yield was 68%, radiochemical purity >99%, and specific activity >74 GBq/µmol. The radioligand properties of Et-[ 18 F]FDL were evaluated using an ex vivo autoradiography and immunohistochemistry in pancreatic tissue sections obtained from mice-bearing orthotopic pancreatic tumor xenografts. Results and Discussion Et-[ 18 F]FDL binding to peritumoral pancreatic tissue sections strongly correlated with HIP/PAP expression ( r = 0.81) and could be completely blocked by treatment with 1 mM lactose. Conclusion These results suggest that Et-[ 18 F]FDL is a promising agent which should be evaluated for detection of early pancreatic carcinomas by PET/CT imaging.