Synthesis of a 68Ga-Labeled Peptoid-Peptide Hybrid for Imaging of Neurotensin Receptor Expression in Vivo

The neurotensin receptor subtype 1 (NTS1) represents an attractive molecular target for imaging various tumors. Positron emission tomography (PET) gained widespread importance due to its sensitivity. We combined the design of a metabolically stable neurotensin analogue with a Ga-68-radiolabeling approach. The Ga-68-labeled peptoid peptide hybrid [Ga-68]3 revealed high stability, specific tumor uptake (0.7 % ID/g, 65 min p.i.), and advantageous biokinetics in vivo using HT29 tumor-bearing nude mice. Because of the ability to internalize into NTS1-expressing tumor cells, [Ga-68]3 proved to be highly suitable for a reliable and practical visualization of NTS1-expressing tumors in vivo by small animal PET.