Preparation and biodistribution studies of a radiogallium-acetylacetonatebis [thiosemicarbazone] complex in tumor-bearing rodents

Various radiometal complexes have been developed for tumor imaging, especially Ga-68 tracer. In the present study, the development of a radiogallium bis-thiosemicarbazone complex has been reported. [[67]Ga] acetylacetonate bis[thiosemicarbazone] complex [[[67]Ga] AATS] was prepared starting [[67]Ga]Gallium acetate and freshly prepared acetylacetonate bis [thiosemicarbazone] [AATS] in 30 min at 90°C. The partition co-efficient and the stability of the tracer were determined in final solution [25°C] and the presence of human serum [37°C] up to 24 h. The biodistribution of the labeled compound in wild-type and fibrosarcoma-bearing rodents were determined up to 72 h. The radiolabled Ga complex was prepared in high radiochemical purity [> 97%, HPLC] followed by initial biodistribution data with the significant tumor accumulation of the tracer in 2 h which is far higher than free Ga-67 cation while the compound wash-out is significantly faster. Above-mentioned pharmacokinetic properties suggest an interesting radiogallium complex while prepared by the PET Ga radioisotope, 68Ga, in accordance with the physical half life, for use in fibrosarcoma tumors, and possibly other malignancies

Preliminary imaging studies of [[61]Cu] diacetyl-bis [N[4]-methylthiosemi-carbazone] in normal and hypoxic tumor models

[[61]Cu] diacetyl-bis [N[4] -methylthiosemicarbazone] [[[61]Cu] ATSM] is a well-established hypoxia imaging tracer with simple production and significant specifity. In this work the accumulation of the tracer is studied in wild-type, necrotic and hypoxic fibrosarcoma tumors. [[61] Cu] ATSM was prepared using ATSM ligand and [[61]Cu] CuOAc followed by i.v. administration and imaging studies in wid-type rats and hypoxic fibrosarcoma-bearing mic.e [[61] Cu] ATSM with high radiochemical purity [>99%, HPLC, RTLC] was injected to wild-type rats as well as hypoxic and necrotic fibrosarcoma-bearing mice followed by imaging up to 3 hours. [[61] Cu] ATSM was mainly accumulated in liver, as well as kidney and bladder and less but still significant in brain of wild-type rats. A significant and hypoxia-specific tumor/non tumor ratio in hypoxic models was observed by co-incidence imaging 2h post inection, while in necrotic and 12-week tumor-induced mice very slight tumor uptakes were detected. [[61]Cu] ATSM is a positron emission tomography [PET] radiotracer for selective tumor hypoxia imaging from necrotic and proliferative tumors