Fluorine-labeled bombesin PET agent a winner for prostate cancer imaging

In a comparison of gastrin-releasing peptide receptor (GRPR) bombesin analogs, F-18 aluminum flouride NODAGA-RM1 showed the most promise for PET imaging of prostate cancer, according to a study published online Nov. 6 in the Journal of Nuclear Medicine.

Investigation of both PET and SPECT agents for prostate cancer are increasingly focused on GRPR-binding agents. Yang Liu, MD, a researcher from the Institute of Nuclear Medicine and Molecular Imaging of Zhejiang University, Center of Excellence in Medical Molecular Imaging, in Hangzhou, China, and colleagues reviewed 1,4,7-triazacyclononane, 1-glutaric acid-4, 7 acetic acid (NODAGA)-conjugated RM1 and AMBA PET agents for their GRPR homing abilities.

All agents were synthesized and, additionally, the RM1 and AMBA agents were radiolabeled with either Cu-64 or F-18 AIF and evaluated in vivo by a preclinical PET imaging system. Results of the study showed that not only can both NODAGA-RM1 and -AMBA be synthesized and radiolabeled, but that –RM1 showed the most GRPR affinity.

“F-18 AlF-labeled NODAGA-RM1 demonstrated excellent serum stability and tumor-imaging properties in the in vitro stability assays and in vivo imaging studies,” wrote Liu et al.

Cu-64 NODAGA-RM1 revealed tumor uptake values of about 3.3, 3.0 and 3.5 percentage injected dose per gram of tissue at 30 minutes, 90 minutes and four hours after injection, respectively. The same for F-18 AlF-NODAGA-RM1 showed significantly higher uptake values at about 4.6, 4.0 and 3.9 at 30 minutes, one hour and two hours, respectively.

“The high-stability, efficient tumor uptake and optimal pharmacokinetic properties highlight F-18 AlF-NODAGA-RM1 as a probe with great potential and clinical application for the PET imaging of prostate cancer,” concluded the researchers.