Radiometallic Complexes of DO3A-Benzothiazole Aniline for Nuclear Medicine Theranostics

To develop a radioactive metal complex platform for tumor theranostics, we introduced three radiopharmaceutical derivatives of 1,4,7,10-tetraazacyclododecane-1,4,7-trisacetic acid-benzothiazole aniline (DO3A-BTA, L1) labeled with medical radioisotopes for diagnosis ( ⁶⁸ Ga/ ⁶⁴ Cu) and therapy ( ¹⁷⁷ Lu). The tumor-targeting ability of these complexes was demonstrated in a cellular uptake experiment, in which ¹⁷⁷ Lu-L1 exhibited markedly higher uptake in HeLa cells than the ¹⁷⁷ Lu-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid complex. According to in vivo positron emission tomography imaging, high accumulation of ⁶⁸ Ga-L1 and ⁶⁴ Cu-L1 was clearly visualized in the tumor site, while ¹⁷⁷ Lu-L1 showed therapeutic efficacy in therapy experiments. Consequently, this molecular platform represents a useful approach in nuclear medicine toward tumor-theranostic radiopharmaceuticals when ⁶⁸ Ga-L1 or ⁶⁴ Cu-L1 is used for diagnosis, ¹⁷⁷ Lu-L1 is used for therapy, or two of the compounds are used in conjunction with each other.