Synthesis and evaluation of Al18F-NODA complex conjugated 2-(4-aminophenyl)benzothiazole as a potential tumor imaging agent

The objective of the study was to prepare and evaluate a F-18-radiolabled tracer ((AlF)-F-18-5), derivated from the antitumor agent 2-(4-aminophenyl)benzothiazole, as a PET probe for tumor imaging. (AlF)-F-18-5 was successfully prepared with approx. 40% radiochemical yield in aqueous phase. In in vitro cell uptake experiments and competition assay, (AlF)-F-18-5 displayed good tumor-binding ability and specificity in HeLa cells (24.7 +/- 0.9% ID/10(6) cells, IC50 = 63.8 +/- 13.6 nM) and MCF-7 cells (6.8 +/- 0.3% ID/10(6) cells, IC50 = 331.1 +/- 33.7 nM). The nonradioactive compound, (AlF)-F-19-5, visibly marked HeLa cells and MCF-7 cells but did not stain HEB cells in florescent staining, which further indicated the tumor-binding ability of (AlF)-F-18-5. In in vivo PET imaging, HeLa and MCF-7 tumors were clearly delineated by specific accumulation of (AlF)-F-18-5 in model mice. In biodistribution study, (AlF)-F-18-5 exhibited good tumor uptake (4.66 +/- 0.13% ID/g and 3.69 +/- 0.56% ID/g, respectively), moderate tumor-to-muscle ratio (3.38 and 2.48, respectively) at 1 h post injection, which were in a good consistency with the results of PET imaging. In conclusion, (AlF)-F-18-5 might be developed as a candidate PET probe for tumor imaging, though additional optimizations are still needed to improve pharmacokinetics in vivo.