Preparation and biodistribution assessment of 68Ga-Bleomycin as a possible PET imaging

Bleomycin is an anti-cancer ( antineoplastic or cytotoxic ) chemotherapy drug which is classified as an antitumor antibiotic.Several radiolabeled Bleomycin derivatives have been developed for imaging and/or therapy of neoplastic tissues. The most important imaging compounds contain indium-111,[1] cobalt-57,[2] technetium-99m,[3] radioferricsalts[4] and rhodium-105 [5].The positron-emitting Ga(III) radioisotopes, 66Ga3+and 68Ga3+, have been proposed for applications inpositron emission tomography (PET) imaging.In this study, by applying a produced 68Ge/68Ga generator,a simple technique for the synthesis and quality control of 68Ga-Bleomycin wasintroduced; followed by preliminary animal studies. 68GaCl3 eluted from the generator was studied in terms of qualitycontrol factors including radiochemical purity (assessed by RTLC),chemical purity and radionuclide purity. This study reports the preparation and biodistribution assessment of Gallium-Bleomycin (68Ga-BLM) complex as a radiopharmaceutical and optimization of its labeling conditions; pH, reaction time, temperature, concentration of Bleomycin and its biodistribution in normal mice. The biodistribution of the complex was compared with 68Ga-Cl3 in 11 selected organs including blood, liver, lung, spleen, muscle, skin, heart, kidney, colon, colon content, and bladder at 4 selected times of 1, 2, 4, 24 hours after injection. The optimized pH condition was found 2 at temperature of 90ºC for reaction temperature of 30 minutes when 1 mg of bleomycin was mixedofabout2mCi of 68Ga-Cl3.Radio thin layer chromatography showed an overall radiochemicalpurity of 90-94% at the optimized conditions with a specific activity of about 1.5mCi/m mole and radiochemical purity greater than 93% in 15 min.