Radioiodination of murine anti-alpha-foetoprotein E.9 monoclonal antibody and its F (ab') 2 fragment for the diagnosis of hepatocellular carcinoma
Beyers, M.; Aspinall, S.; Conradie, J.D.; Fourie, P.J.
Nuklearmedizin. Nuclear Medicine 27(3): 87-94
1988
ISSN/ISBN: 0029-5566 PMID: 2457207 Document Number: 319097
The high incidence of hepatocellular carcinoma amongst certain population groups of Southern Africa made feasible the investigation of a radiolabeled monoclonal anti-alphafetoprotein as a radioimmunodiagnostic agent for this disease. This paper reports the preclinical trials with monoclonal antialphafoetoprotein E.9 (anti-AFP) and its F(ab')2 fragment after radiolabelling with 131I. Various radioiodinations were tried. The best results were obtained with the lodogen and Bolton-Hunter methods. 131I from only one of the sources tested gave and 131I-labelled anti-AFP with meaningful immunoreactivity . It was shown by means of gamma-camera scans and monitoring of radioactivity in individual organs that 131I-anti-AFP and the 131I-anti-AFP F(ab')2 fragments did not accumulate abnormally in any organ(s) in healthy animals. The correlation in healthy mice of the biodistribution of 125I human IgG to 131I-anti-AFP, and 125I human IgG to 131I-F(ab')2 was good. Human hepatoma xenografts in athymic mice showed uptake of 13I-anti-AFP and the 13I-F(ab')2 fragment. The uptake of 131I-F(ab')2 was improved by liver background subtraction. There was correlation between circulatory alphafoetoprotein concentrations and tumor uptake of 131I-F(ab')2 in tumor-bearing athymic mice and a definite relationship was found between tumor size and radiolabeled antibody and the F(ab')2 fragment. After the biological action of the 131I-anti-AFP and the 131I-F(ab')2 fragment was known, sterile pyrogen-free consignments were supplied for clinical trials in humans on a regular basis.