18F-FP-PEG2-β-Glu-RGD2: A Symmetric Integrin αvβ3-Targeting Radiotracer for Tumor PET Imaging

Radiolabeled cyclic arginine-glycine-aspartic (RGD) peptides can be used for noninvasive determination of integrin alpha(v)beta(3) expression in tumors. In this study, we performed radiosynthesis and biological evaluation of a new F-18-labeled RGD homodimeric peptide with one 8-amino- 3,6-dioxaoctanoic acid (PEG(2)) linker on the glutamate beta-amino group(F-18-FP-PEG(2)-beta-Glu-RGD(2)) as a symmetric PET tracer for tumor imaging. Biodistribution studies showed that radioactivity of F-18-FP-PEG(2)-beta-Glu-RGD(2) was rapidly cleared from blood by predominately renal excretion. MicroPET-CT imaging with F-18-FP-PEG(2)-beta-Glu-RGD(2) revealed high tumor contrast and low background in A549 human lung adenocarcinoma-bearing mouse models, PC-3 prostate cancer-bearing mouse models, and orthotopic transplanted C6 brain glioma models. F-18-FP-PEG(2)-beta-Glu-RGD(2) exhibited good stability in vitro and in vivo. The results suggest that this tracer is a potential PET tracer for tumor imaging.