Abstract
1353
Objectives Selective Internal Radiation Therapy (SIRT) of Hepatocellular Carcinoma (HCC) using yttrium-90 microspheres requires a pre-therapeutic step with a different vector, the 99mTc-macroaggregated albumin. This difference may reduce the precision of the pre-therapeutic dosimetry. To overcome this problem the aim of this work was to develop, validate and optimize the radiolabeling of Starch-Based Microparticles (SBMP) by 188Re and 68Ga in the form of ready-to-use radiolabeling kits, in order to obtain a unique theranostic vector for the treatment of HCC.
Methods Optimal labeling conditions and composition of freeze-dried kits for 188Re and 68Ga were defined by monitoring the Radiochemical Purity (RCP) while varying several parameters. The in vitro stability was assessed in complex media and histidine solution. An in vivo biodistribution was carried out as a proof of concept with the intra-arterial injection of 68Ga radiolabeled SBMP (68Ga-SBMP) in HCC diethylnitrosamine-induced rats followed by PET/CT acquisition.
Results All radiolabeling reactions were realized at room temperature. 188Re dedicated kits were developed with a RCP>95% with the following parameters: 300mg of SBMP, 1mg of SnCl2 and 30mg of Na gluconate. A stable RCP蠅98% was obtained with 100mg of SBMP by direct labelling with 68GaCl3 eluate. These results were optimized by adding pH4.1 acetate buffer to reach a RCP>99% from 5min after the beginning of the radiolabeling reaction. The in vivo injection of 68Ga-SBMP into the hepatic artery and 20min PET acquisition showed that all the activity was found in the liver, in particular in the tumor.
Conclusions The SBMP as a unique vector is a promising theranostic agent for the SIRT of HCC. RESEARCH SUPPORT: Thesis project funded by the Ministry of Education and Research into the Erasmus Mundus program NanoFar.