Evaluation of 99mTc-BFCA-NT(8-13) for potential application in breast cancer diagnosis

1918 Objectives Neurotensin and its receptor NTR-1 are known to contribute to the neurotensinergic cascade within the malignant MDA-MB-231 human breast cancer progression. The purpose of this study was the comparison of the biological behavior of Neurotensin (8-13) analog radiolabeled with 99mTc using HYNIC and NHS-Sacetyl-MAG3 as chelating agents in animals bearing breast cancer cell line. Methods Radiolabeling procedures for each radioconjugate were performed. Radiochemical purity was checked by ITLC-SG and HPLC. Biodistribution and imaging studies were carrried out in Nude mice bearing human breast cancer cells (MDA-MB 231) at 30 and 90 min post-injection. Blocking evaluation was also conducted by co-injection of 115 nmol of NT (8-13). Results Radiochemical purity was greater than 97% for both radioconjugates. A faster washout from tumor (2.0± 0.2 and 0.4± 0.1 %ID/g) at 30 and 90 min was observed for the HYNIC radioconjugate in comparison with the MAG3 molecule (1.9± 0.5 and 1.8± 0.7 %ID/g). At the same time, higher tumor/blood (16.9) and tumor/muscle (11.7) ratio at 90 min was achieved with MAG3, and more than 60% ID/g of tumor and small intestine uptake was blocked, versus just 45.9% and 36.4% ID/g respectively, in the case of HYNIC . Conclusions Differences in tumor uptake were not very remarkable for the two radiocomplexes. Nevertheless, when MAG3 was used better biological performance occurred due to longer retention time in tumor, as well as a notable specificity in blocking studies.