Immunolocalization of hepatic metastases of human colonic cancer by chimeric anti-TAG72 antibody in SCID mice.

TAG72 is a well-characterized, human tumor-associated antigen present in > 85% of human colonic cancers. In this study, we established an animal model of hepatic metastases of human colonic carcinoma. The high-mucin variant cell line, designated HM7, was derived from the human colonic carcinoma cell line LS174T. Following intrasplenic injection, HM7 was able to induce much greater hepatic metastases in SCID mice compared to its parental cell line LS174T. Numerous hepatic metastases were evident 18 days subsequent to the intrasplenic injection of tumor cells. Using the chimeric anti-TAG72 antibody ccM4, immunohistochemistry demonstrated strong expressions of the TAG72 antigen in these metastases. Our biodistribution and imaging data also showed that the radiolabelled ccM4 antibody was able to localize hepatic metastases in the SCID mice. Based upon these findings, w anticipate that the herein described SCID mouse model will prove most useful in studying hepatic metastases of human colonic carcinoma by using anti-TAG72 therapeutic immunoreagents.