Ga-68-NOTA-Aca-BBN(7-14) PET/CT in Healthy Volunteers and Glioma Patients

This work was designed to study the safety, biodistribution, and radiation dosimetry of a gastrin-releasing peptide receptor (GRPR)-targeting, Ga-68-labeled bombesin (BBN) peptide derivative PET tracer, NOTA-Aca-BBN(7-14) (denoted as Ga-68-BBN) in healthy volunteers and to assess the level of receptor expression in glioma patients. Methods: Four healthy volunteers (2 male and 2 female) underwent whole-body PET/CT at multiple time points after a bolus injection of Ga-68-BBN (111 +/- 148 MBq). Regions of interest were drawn manually over major organs, and time-activity curves were obtained. Dosimetry was calculated using the OLINDA/EXM software. Twelve patients with glioma diagnosed by contrast-enhanced MRI underwent PET/CT at 30-45 min after Ga-68-BBN injection. Within 1 wk afterward, the tumor was surgically removed and immunohistochemical staining of tumor samples against GRPR was performed and correlated with the PET/CT results. Results: Ga-68-BBN was well tolerated in all healthy volunteers, with no adverse symptoms being noticed or reported. Ga-68-BBN cleared rapidly from the circulation and was excreted mainly through the kidneys and urinary tract. The total effective dose equivalent and effective dose were 0.0335 +/- 0.0079 and 0.0276 +/- 0.0066 mSv/MBq, respectively. In glioma patients, all MRI-identified lesions showed high signal intensity on Ga-68-BBN PET/CT. SUVmax and SUVmean were 2.08 +/- 0.58 and 1.32 +/- 0.37, respectively. With normal brain tissue as background, tumor-to-background ratios were 24.0 +/- 8.85 and 13.4 +/- 4.54 based on SUVmax and SUVmean, respectively. The immunohistochemical staining confirmed a positive correlation between SUV and GRPR expression level (r(2) = 0.71, P < 0.001). Conclusion: Ga-68-BBN is a PET tracer with favorable pharmacokinetics and a favorable dosimetry profile. It has the potential to evaluate GRPR expression in glioma patients and guide GRPR-targeted therapy Of glioma.