[²⁰¹Tl](III)-bleomycin for tumor imaging

Abstract

Summary Due to interesting physical properties and wide availability of thallium-201 as a SPECT radionuclide, the idea of incorporation of this nuclide into biologically active compounds was targeted. Thallium-201 ( T 1/2 = 3.04 d) in Tl + form was converted to Tl 3+ cation in presence of O 3 in 6 M HCl controlled by RTLC/gel electrophoresis methods. The final evaporated activity was reacted with bleomycin in normal saline to yield [ 201 Tl]BLM at room temperature after 0.5 h (radiochemical yield > 99%) followed by HPLC analysis. The studies showed that thallic ion is mostly incorporated into bleomycin A 2 while other species in the pharmaceutical sample almost remain unlabeled. Radiochemical purity of more than 99% was obtained using RTLC, HPLC with specific activity of about 7 Ci/mmol. The stability of the tracer was checked in the final product in presence of human serum at 37 °C up to 3 d. The tracer accumulated in tumors of fibrosarcoma-bearing mice after 72 h.