The antitumor properties of
antibodies to the beta-subunit of hCG (
hCG beta) coupled to
tetanus toxoid (tt) were studied in hamsters implanted with the BeWo strain of human
choriocarcinoma. After active immunization with
hCG beta-tt mixed in complete
Freund's adjuvant, hamsters synthesized large quantities of
antibodies which bound whole hCG, as measured in vitro by the binding of radiolabeled hCG to plasma. Scatchard binding analysis indicated that the total high affinity hCG-binding capacity of
hCG beta-tt plasma was approximately 130 microgram/ml. However, these
antibodies were devoid of any antitumor activity.
Choriocarcinoma implanted into hamsters during the peak times of [125I]
iodo-hCG-binding activity by plasma did not show any change in
tumor volume over a 20-day period of
tumor growth compared to
tumors in hamsters immunized with tt alone. Active immunization with
hCG beta-tt did not alter the percentage of
tumors taking, the length of lag phase of
tumor growth, or the initial day of grossly detectable
tumor necrosis. These results suggest that active immunization with
hCG beta-tt will not alter the growth of transplantable
choriocarcinoma.