Immunoscintigraphy of xenotransplanted hepatoblastoma with iodine 131-labeled anti-alpha-fetoprotein monoclonal antibody

Background/Purpose: Hepatoblastoma (HB) is the most common primary malignan t liver tumor affecting infants and young children. The alpha-fetoprotein l evel is elevated in 95% of all children with hepatoblastoma. Therefore, it is of interest to assess targeting of the HE marker alpha-fetoprotein by an tibody imaging. In this pilot study, the authors investigated the radioimmu noscintigraphy of xenotransplanted HE in nude mice utilizing an anti-alpha- fetoprotein antibody. Methods: HE cell suspensions from tumors of 3 children were transplanted su bcutaneously into nude mice NMR (nu/nu). A total of 200 mu g of intact anti -alpha-fetoprotein antibody was injected intravenously into 8 animals from each HE. Before injection, the monoclonal antibody was labeled with iodine (I) 131 (specific activity of 75 MBq/mg, labeling yield of 95%) using the c onventional iodogen method. Planar scintigraphic images of anesthetized mic e in posterior Views were acquired with a gamma camera immediately after in jection, and after 1, 2, 3, 7, and 14 days. The biodistribution data were o btained by killing and dissecting animals, and the activity in the tissues was measured in a gamma counter. The alpha-fetoprotein levels in the animal s' sera were recorded 15 days after imaging and were compared with the cont rol group. Results: A total of 66% of the hepatoblastomas could be detected by scintig raphy. Within 24 hours, the mean specific tumor uptake in nude mice hepatob lastomas with a volume of over 1,000 mm(3), was 14% per injected dose (+/-3 .9%). The biological half-life of the labeled antibody complex in the tumor was 3.86 (+/-0.84) days. Thyroid uptake of free I-131 was 2.85% per inject ed dose (+/-1.5%) reflecting the deiodination of the labeled antibody compl ex. Conclusions: The results show the possibility of imaging xenotransplanted h epatoblastoma with I-131-labeled anti-alpha-fetoprotein and may, in the fut ure, determine tumor recurrence and extension, and thereby improve the prog nosis of advanced HBs. J Pediatr Surg 34:1378-1384. Copyright (C) 1999 by W .B. Saunders Company.