Antimicrobial peptide 99mTc-UBI 29-41 for infection diagnosis: Kit formulation and a preliminary clinical study

Antimicrobial peptides that show specific binding to pathogens are potential precursors for the differential diagnosis of infections. The ubiquicidin derived peptide UBI 29-41 labelled with 99mTc was previously studied as part of the design of a radiopharmaceutical showing good physicochemical and biological properties. In searching for the clinical application of this labelled peptide, the research focused on the optimization of a lyophilized kit composition, labelling parameters such as time and temperature of incubation, as well as on storage conditions. The best labelling results were obtained for a kit containing 50.0 μg of UBI 29-41, 4.4 μg of SnF2, 13.6 μg of Na2P2O7 and 70.0 μg of KBH4, incubated with the pertechnetate in a boiling bath for 5 min. Radiochemical purity was higher than 95%. It showed a good stability at room temperature over 24 h. Studies of stability in human serum and cysteine challenge tests were performed, rendering good results. The kit was stable for more than five months at 4 deg C. Biological evaluation on mice with S. aureus induced infection indicated a differential uptake between normal and infected tissue. On the basis of promising preclinical results of 99mTc-UBI 29-41, a patient with a hip prothesis was studied. The results obtained encourage more work on its possible future routine use in nuclear medicine. (author)