Radiology, Vol 149, 549-555, Copyright © 1983 by Radiological Society of North America
Metastatic colon carcinoma detected with radiolabeled F(ab')2 monoclonal antibody fragments
PJ Moldofsky, J Powe, CB Mulhern Jr, N Hammond, HF Sears, RA Gatenby, Z Steplewski and H Koprowski
Nine patients with colonic carcinoma were studied with I-131-labeled
F(ab')2 fragments of an anti-colorectal carcinoma monoclonal antibody. A
total of 69% of colon cancer sites were detected without background
subtraction; metastases from a concurrent breast carcinoma in one patient
were not seen. Lesions ranged from 1.5 to 8 cm. The mean thyroid uptake of
I-131 at 24 hours was 0.25%. Half-lives of I-131 in the blood
(protein-bound and total) fit a two-compartment model, with half-lives of
3.5 and 27.6 hours for the protein-bound fraction and 3.6 and 23.8 hours
for total I-131. Using quantitative methods, a mean value of 0.0047%/cm3 of
the administered dose was localized in the tumor at peak concentration,
which occurred approximately 48 hours post- administration. This has
implications for therapy planning.
