ABSTRACT
PURPOSE: We explored the imaging of bombesin receptors and evaluated the clinical use of [(99m)Tc]Demobesin 4 ([(99m)Tc]DB4) in prostate cancer patients. PROCEDURES: [(99m)Tc]DB4 was prepared according to Good Manufacturing Practice. Patients with prostate cancer underwent serial planar and SPECT imaging up to 3 h after administration. Blood and urine samples were taken to assess pharmacokinetics. RESULTS: [(99m)Tc]DB4 is safe and clears rapidly from the bloodstream via the kidneys resulting in low background activity. The tracer binds strongly to the gastrin-releasing peptide receptor (GRPR) in vivo as indicated by the high uptake in the pancreas seen in all patients. In patients who had undergone hormone therapy, [(99m)Tc]DB4 did not efficiently image metastatic prostate cancer. In contrast, in newly diagnosed patients local disease was visualised. CONCLUSIONS: The GRPR is an unsuitable target for imaging refractory prostate cancer but may be useful in untreated disease. [(99m)Tc]DB4 is a promising radiopharmaceutical which merits further exploration in this specific group of patients.
