Clinical evaluation of antimicrobial peptide [99mTc/Tricine/HYNIC0]ubiquicidin 29–41 as a human-specific infection imaging agent

Abstract Introduction Ubiquicidin (UBI) 29–41 is a cationic synthetic antimicrobial peptide fragment that binds preferentially with the anionic microbial cell membrane at the site of infection. This study was conducted to evaluate the potentiality of [ 99m Tc/Tricine/HYNIC 0 ]UBI 29–41 prepared from lyophilized kits as an infection imaging agent in humans. Methods Seven patients (5 males and 2 females; mean age=55 years; age range=35–75 years) with suspected bone or soft-tissue infections participated in this study. [ 99m Tc/Tricine/HYNIC]UBI 29–41, corresponding to activity in the range 555–740 MBq added to 40 μg of peptide obtained from instant freeze-dried kit formulations with radiochemical purities >95%, was injected intravenously. A 45-min dynamic study was followed by spot views of the suspected region of infection (target) and a corresponding normal area (nontarget). Whole-body anterior and posterior images were also acquired at 30, 60 and 120 min after injection. True- or false-positive or true- or false-negative images were interpreted upon bacterial culture, radiography, clinical tests and bone scanning. Results The biodistribution of [ 99m Tc/Tricine/HYNIC]UBI 29–41 in patients showed rapid accumulation of activity in the kidneys in the first 30 min after injection that gradually declined and accumulated in the urinary bladder. There were positive findings in five studies and negative findings in two. Findings were subsequently confirmed to be true positive or negative. Images showed minimal accumulation in nontarget tissues, with an average target/nontarget ratio of 2.10±0.33 in positive lesions at 30 min. Conclusion Given its favorable clinical characteristics, [ 99m Tc/Tricine/HYNIC]UBI 29–41 shows promise as a tracer for infection imaging that allows early diagnosis (30 min) of infection.