[(99m)Tc]Tc-DGA1, a Promising CCK(2)R-Antagonist-Based Tracer for Tumor Diagnosis with Single-Photon Emission Computed Tomography

Radiolabeled gastrin analogues have been proposed for theranostics of cholecystokinin subtype 2 receptor (CCK(2)R)-positive cancer. Peptide radioligands based on other receptor antagonists have displayed superior pharmacokinetics and higher biosafety than agonists. Here, we present DGA1, a derivative of the nonpeptidic CCK(2)R antagonist Z-360 carrying an acyclic tetraamine, for [(99m)Tc]Tc labeling. Preclinical comparison of [(99m)Tc]Tc-DGA1 with [(99m)Tc]Tc-DG2 (CCK(2)R-agonist reference) was conducted in HEK293-CCK(2)R/CCK(2i4sv)R cells and mice models, qualifying [(99m)Tc]Tc-DGA1 for further study in patients with CCK(2)R-positive tumors and single-photon emission computed tomography/CT.