In Vivo Evaluation of a Bombesin Analogue Labeled with Ga-68 and Co-55/57

PURPOSE - The purpose of this study was to apply an analogue of bombesin, NOTA-AMBA, labeled with Co-55 or Ga-68, for preclinical imaging of prostate cancer.

PROCEDURES - The peptide NOTA-AMBA was labeled with Ga-68 or Co-55 by microwave irradiation.

Biodistribution in xenograft mice (PC3) was performed at 1, 4, and 24 h (only cobalt at 24 h) using a fixed amount of peptide. Four weeks post-inoculation, xenograft mice were positron emission tomography/X-ray computed tomography scanned after tail vein injection of [(68)Ga]NOTA-AMBA or [(55)Co]NOTA-AMBA.

RESULTS - Labeling with Ga-68 and Co-55/57 was achieved in yields greater than 90 %. A radiochemical purity (RCP) of 95 and 90 % were obtained for Ga-68 and Co-55, respectively. Both radiopeptides showed high uptake in the intestines, stomach, pancreas, and in the tumor ([(68)Ga]NOTA-AMBA, 10. 3 %ID/g at 1 h to 6. 4 %ID/g at 4 h; [(57)Co]NOTA-AMBA, 8. 2 %ID/g at 1 h to 5. 3%ID/g at 24 h). Normal tissue cleared over time improving tumor-to-background ratios.

CONCLUSIONS - NOTA-AMBA was labeled in high yields and RCP with Ga-68 and Co-55/57. High tumor uptake in a subcutaneous mouse prostate cancer model was observed. At 24 h, [(55/57)Co]NOTA-AMBA showed better tumor-to-organ ratios than [(68)Ga]NOTA-AMBA at both 1 and 4 h post-injection. Hence, for imaging, [(55)Co]NOTA-AMBA was found to be superior compared to [(68)Ga]NOTA-AMBA.

Molecular imaging and biology : MIB : the official publication of the Academy of Molecular Imaging. 2015 Nov 11 [Epub ahead of print]

Johan Hygum Dam, Birgitte Brinkmann Olsen, Christina Baun, Poul-Flemming Høilund-Carlsen, Helge Thisgaard

Department of Nuclear Medicine, Odense University Hospital, Sdr. Boulevard 29, 5000, Odense, Denmark. Department of Nuclear Medicine, Odense University Hospital, Sdr. Boulevard 29, 5000, Odense, Denmark. , Department of Nuclear Medicine, Odense University Hospital, Sdr. Boulevard 29, 5000, Odense, Denmark. , Department of Nuclear Medicine, Odense University Hospital, Sdr. Boulevard 29, 5000, Odense, Denmark. , Department of Nuclear Medicine, Odense University Hospital, Sdr. Boulevard 29, 5000, Odense, Denmark.

PubMed

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