<em>68</em>Ga-Labeled Cyclic NGR Peptide for MicroPET Imaging of CD13 Receptor Expression.

Peptides containing the asparagines-glycine-arginine (NGR) motif have been identified as specific ligands binding to CD13/aminopeptidase N (APN) receptor, a tumor neovascular biomarker. In this study, we synthesized a novel NGR-containing peptide (NOTA-G₃-NGR), and labeled NOTA-G₃-NGR with ⁶⁸Ga (t1/2 = 67.7 min). The resulting ⁶⁸Ga-NOTA-G₃-NGR peptide was subject to in vitro and in vivo characterization. The microPET imaging results revealed that the ⁶⁸Ga-NOTA-G₃-NGR peptide exhibits rapid and specific tumor uptake, and high tumor-to-background contrast in a subcutaneous HT-1080 fibrosarcoma mouse model. We concluded that the ⁶⁸Ga-NOTA-G₃-NGR peptide has potential in the diagnosis of CD13-targeted tumor angiogenesis. [ABSTRACT FROM AUTHOR]