Study On The 188Re Labeling Of Anti-human Hepatoma Monoclonal Antibody Fragment 188Re-HAb18-Fab'

Anti-human hepatoma monoclonal antibody fragment HAb18 F (ab' )₂ is the newest productof 863 Hepatoma Targeting Research Center on Department of Pathology at the fourth militarymedical university.¹⁸⁸Re has become the emphasis as its excellent nuclear characters. It will beable to develop a kind of a new therapeutic agent for hepatocellular carcinoma .The research hasbeen done is listed as follows:(1) We have investigated various factors affecting the labeling efficiency underthe best labeling conditions, and established the method for measuring radiochemicalpurity composed of paper chromatography and HPLC.(2)We have determined the numbers of thiols of the reduced antibody fragmentsby Ellman's method and the immunoreactivity using a modified in vitro cell bindingassay, and analyzed the in vitro stability challenged with DTPA. L-cysteine (thechallenging agent to the labeled antibody molar ratios are 700: 1 and 200 : 1 )andsaline;(3)We also studied the blood clearance in New Zealand rabbit, the tissuebiodistribution in normal and tumor-bearing rats, and RII in tumor-bearing rats.The radiochemical purity can achieve 85%⁹5% under the best conditions and becomegreater than 98% after further purification. Both paper chromatography and HPLC can be used todetermine the radiochemical purity. Paper chromatography was much more convenient. ButHPLC can conform the quality of the labeled antibody. The number of thiols andimmunoreactive fraction reached 2. 4 per molecule and 0.91. The in vitro stabilityof the labeled antibody was perfect.The results of animals showed that the labeled antibodies can be cleared fromblood fast, eliminated mainly by kidney, and concentrated significantly in tumor.The tumor can be visualized at 5h after injection and become clear at 9h up to 48h.Such demonstrates that ¹⁸⁸Re-HAb18-Fab' may be used for hepatocellular carcinoma therapyby liver artery intubatton.