Immunoscintigraphy of xenotransplanted hepatoblastoma with iodine 131-labeled anti-alpha-fetoprotein monoclonal antibody.
OBJECTIVE
Hepatoblastoma (HB) is the most common primary malignant liver tumor affecting infants and young children. The alpha-fetoprotein level is elevated in 95% of all children with hepatoblastoma. Therefore, it is of interest to assess targeting of the HB marker alpha-fetoprotein by antibody imaging. In this pilot study, the authors investigated the radioimmunoscintigraphy of xenotransplanted HB in nude mice utilizing an anti-alpha-fetoprotein antibody.


METHODS
HB cell suspensions from tumors of 3 children were transplanted subcutaneously into nude mice NMRI (nu/nu). A total of 200 microg of intact anti-alpha-fetoprotein antibody was injected intravenously into 8 animals from each HB. Before injection, the monoclonal antibody was labeled with iodine (I) 131 (specific activity of 75 MBq/mg, labeling yield of 95%) using the conventional iodogen method. Planar scintigraphic images of anesthetized mice in posterior views were acquired with a gamma camera immediately after injection, and after 1, 2, 3, 7, and 14 days. The biodistribution data were obtained by killing and dissecting animals, and the activity in the tissues was measured in a gamma counter. The alpha-fetoprotein levels in the animals' sera were recorded 15 days after imaging and were compared with the control group.


RESULTS
A total of 66% of the hepatoblastomas could be detected by scintigraphy. Within 24 hours, the mean specific tumor uptake in nude mice hepatoblastomas with a volume of over 1,000 mm3, 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 injected dose (+/-1.5%) reflecting the deiodination of the labeled antibody complex.


CONCLUSIONS
The results show the possibility of imaging xenotransplanted hepatoblastoma with 131I-labeled anti-alpha-fetoprotein and may, in the future, determine tumor recurrence and extension, and thereby improve the prognosis of advanced HBs.
Fuchs
J
J
Department of Pediatric Surgery, Medical School Hannover, Germany.
Gratz
K F
KF
Habild
G
G
Gielow
P
P
von Schweinitz
D
D
Baum
R P
RP
D000818:Animals; D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; D002675:Child, Preschool; D005260:Female; D018197:Hepatoblastoma / Q000000981:diagnostic imaging*; D006801:Humans; D007223:Infant; D007457:Iodine Radioisotopes / Q000378:metabolism; D008113:Liver Neoplasms / Q000000981:diagnostic imaging*; D051379:Mice; D008819:Mice, Nude; D010865:Pilot Projects; D016719:Radioimmunodetection; D014018:Tissue Distribution; D000509:alpha-Fetoproteins / Q000032:analysis*
D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; D007457:Iodine Radioisotopes; D000509:alpha-Fetoproteins