Advanced Techniques in Biology & Medicine
Open Access

Abstract

Development of a 68Ga-Labeled Bombesin Analog for Gastrin-Releasing Peptide Receptor-Expressing Prostate Tumor Imaging

Jae Cheong Lim, So Hee Dho, Eun Ha Cho, So Young Lee, Soo Yong Kim, Sung Hee Jung and Jong Choon Kim

Our previous study demonstrated the therapeutic efficacy of 177Lu-DOTA-gluBBN for the treatment of GRPRexpressing prostate tumors. As a matched pair for 177Lu, the development of labeling and molecular imaging technology using 68Ga is needed to introduce the “theranostic” approach. Therefore, the present study described the 68Ga-labeled bombesin analog, 68Ga-DOTA-gluBBN for the imaging of GRPR-expressing prostate tumors.

Methods: 68Ga was concentrated and labeled with DOTA-gluBBN using the NaCl method, and the labeling yield was evaluated by iTLC-SG. Human prostate PC-3 tumor cells were used to induce a subcutaneously xenografted-tumor model and a peritoneal metastasized tumor model. PET-CT imaging studies were performed in both animal models.

Results: Eluted 68Ga solution containing 5~10% of impurities was purified (>99%) and labeled with DOTA-gluBBN with a high incorporation yield (>98%). The total preparation time from the elution and quality control steps required below twenty minutes. 68Ga-DOTA-gluBBN was clearly visualized in xenografted PC-3 tumors at 1 hr p.i., and the tumor-tomuscle ratio was 1.7-fold higher than that observed using 18F-FDG. In a peritoneal metastasized tumor model, PC-3 tumors were widespread in peritoneum. The metastases could not be specifically visualized by PET imaging, but the tumor uptake was confirmed by ex-vivo autoradiography.

Conclusion: Favorable preclinical results demonstrating specific and effective imaging of GRPR-expressing prostate tumor recommend the further evaluation of 68Ga-DOTA-gluBBN in a clinical study to introduce a theranostic approach for prostate carcinoma patients.