Preparation, biological characterization and preliminary human imaging studies of (68)Ga-DOTA-IBA

PURPOSE: In this study, DOTA-IBA was radiolabeled with (68)Ga and we determined the optimum labelling conditions and assessed the biological properties of (68)Ga-DOTA-IBA. We investigated the biodistribution of (68)Ga-DOTA-IBA in normal animals and undertook PET/CT imaging in humans. Finally, we explored the feasibility (68)Ga-DOTA-IBA as a bone imaging agent and demonstrated its potential for the therapeutic release of (177)Lu/(225)Ac-DOTA-IBA. METHODS: The controlled variables method was used to assess the impact of variables on the radiochemical purity of (68)Ga-DOTA-IBA. The biological properties of (68)Ga-DOTA-IBA were investigated.(68)Ga-DOTA-IBA micro-PET/CT imaging was performed on animals. Volunteers were recruited for (68)Ga-DOTA-IBA imaging and data were compared to (99m)Tc-MDP imaging studies to calculate the target to non-target ratio (T/NT) of the lesions. RESULTS: The prepared (68)Ga-DOTA-IBA had a radiochemical purity of >97% and demonstrated good biological properties with a good safety profile in normal mice. PET/CT imaging of the animals showed rapid blood clearance with high contrast between the bone and stroma. Human imaging showed that (68)Ga-DOTA-IBA could detect more lesions compared to (99m)Tc-MDP and had a higher targeted to untargeted ratio. CONCLUSIONS: (68)Ga-DOTA-IBA is an osteophilic radiopharmaceutical that can be synthesized using a simple labelling method. (68)Ga-DOTA-IBA has high radiochemical purity and is stable in vitro stability. It is rapidly cleared from the blood, has low toxicity and has strong targeting to the bone with long retention times. We also found that it is rapidly cleared in non-target tissues and has high contrast on whole-body bone imaging. (68)Ga-DOTA-IBA PET/CT has potential as a novel bone imaging bone modality in patients with metastatic disease.