Preclinical Evaluation of Gastrin-Releasing Peptide Receptor Antagonists Labeled with Tb and Lu: A Comparative Study.

To elucidate potential benefits of the Auger-electron-emitting radionuclide Tb, we compared the preclinical performance of the gastrin-releasing peptide receptor antagonists RM2 (DOTA-Pip-d-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH) and AMTG (α-Me-Trp-RM2), each labeled with both Lu and Tb. Tb/Lu labeling (90°C, 5 min) and cell-based experiments (PC-3 cells) were performed. In vivo stability (30 min after injection) and biodistribution studies (1-72 h after injection) were performed on PC-3 tumor-bearing CB17-SCID mice.