Evaluation of a series of new 99mTc-labeled bombesin-like peptides for early cancer detection

Bombesin (BN) is a peptide exhibiting a high affinity for the gastrin-releasing peptide (GRP) receptor, which is overexpressed by a variety of tumors, including breast or prostate cancer. The aim of the present study was the investigation of the complexes formed between a series of BN-like peptides and the nuclides Re-185/187 and Tc-99m. The Re-185/187 complexes were formed via the precursor Re-gluconate. The radiolabeling of the derivatives with Tc-99m was performed using either Tc-99m-gluconate or Tc-99m-MDP as the intermediate complex. For the in vitro evaluation of the new peptides, the cancer cell line PC3 was used. The in vivo behavior of the Tc-99m-labeled BN-like peptides was evaluated in normal mice. All the derivatives showed specific uptake in the pancreas, an organ rich in BN receptors and high affinity for the cancer cell line PC3. The above preliminary results indicated that the new BN derivatives are promising for human cancer studies.