68-Ga-labeled NODAGA-RGD-BBN heterodimer peptide as a novel radiotracer for dual integrin and GRPR-targeted tumor imaging

Due to the excellent physical and biochemical characteristics of 68Ga, 68Ga-1,4,7-triazacy–clononane–glutaric acid– 4,7 acetic acid- arginyl-glycyl-aspartic acid- bombesin (68Ga-NODAGA-RGD-BBN) was prepared as a new positron emission tomography (PET) imaging agent, and afterward, the preclinical evaluation of this labeled peptide was studied.

68Ga radioisotope was extracted from a 68Ge/68Ga generator with high radionuclide, chemical and radiochemical purities. Then; the 68Ga-NODAGA-RGD-BBN radiolabeled complex was prepared at optimized conditions. The stability of the complex was evaluated in phosphate-buffered saline (PBS) for at least 2 h. Cell studies of the radiolabeled peptide were also assessed on the gastrin releasing peptide receptor (GRPR)-expressing cell line. Finally; the biodistribution and whole-body scan imaging study of 68Ga-NODAGA-RGD-BBN was studied in normal and tumor-bearing mice.

The biodistribution and whole-body scan imaging of the radiolabeled compound on GRPR-expressing tumor-bearing mice demonstrated the high uptake in the tumor site at all post-injection intervals.  The biodistribution results also demonstrated the major excretion route of the complex is the urinary tract.

68Ga-NODAGA-RGD-BBN shows high potential for PET imaging of patients with GRPR-expressing tumors; however, more biological studies are still needed.