68Ga-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 (68)Ga (t1/2 = 67.7 min). The resulting (68)Ga-NOTA-G3-NGR peptide was subject to in vitro and in vivo characterization. The microPET imaging results revealed that the (68)Ga-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 (68)Ga-NOTA-G3-NGR peptide has potential in the diagnosis of CD13-targeted tumor angiogenesis.