[68Ga]Ga-DOTA-DP-UBI 29-41: A Novel 68Ga-Labeled Ubiquicidin 29-41 Derivative Containing d-Proline for Bacterial...

Area of Science:

• Nuclear Medicine
• Radiochemistry
• Infectious Diseases

Background:

• Bacterial infections present a significant global health challenge.
• Distinguishing bacterial infections from sterile inflammation is crucial for effective patient management.
• Current diagnostic methods may lack specificity or timeliness.

Purpose of the Study:

• To develop and evaluate a novel ⁶⁸Ga-labeled radiotracer, [⁶⁸Ga]Ga-DOTA-DP-UBI 29-41, for imaging bacterial infections.
• To assess the tracer's ability to differentiate bacterial infection from sterile inflammation.
• To investigate the tracer's pharmacokinetic and biodistribution properties.

Main Methods:

• Radiosynthesis of [⁶⁸Ga]Ga-DOTA-DP-UBI 29-41 using DOTA-DP-UBI 29-41 and ⁶⁸Ga.
• In vitro characterization including radiochemical purity, stability, and binding assays with *Staphylococcus aureus*.
• In vivo biodistribution studies and PET/CT imaging in mouse models with bacterial infection and sterile inflammation.

Main Results:

• The novel radiotracer [⁶⁸Ga]Ga-DOTA-DP-UBI 29-41 was successfully synthesized with high radiochemical purity (>98%) and stability.
• In vitro studies demonstrated specific and rapid binding to *Staphylococcus aureus*.
• In vivo studies showed effective accumulation at infection sites, reduced renal uptake compared to previous analogs, and a significant infection-to-inflammation ratio (2.11 at 120 min p.i.).
• PET/CT imaging clearly visualized bacterial infection foci and differentiated them from sterile inflammation.

Conclusions:

• [⁶⁸Ga]Ga-DOTA-DP-UBI 29-41 is a promising PET tracer for the specific diagnosis of bacterial infections.
• The tracer demonstrates excellent potential for differentiating bacterial infections from sterile inflammatory processes.
• This novel agent could improve clinical management of infections through accurate and timely imaging.