Radioimmunotherapy of carcinoma of colon with [131I]-labeled recombinant chimeric monoclonal antibodies to carcinoembryonic antigen

Abstract

Aim: To study the distribution of [(131)I]-labeled anti-CEA MoAbs and its therapeutic effect on the human colonic cancer model in nude mice.

Methods: A nude mice model of human colonic cancer was established. [(131)I]-labeled anti-CEA MoAbs were injected intravenously into mice. The distribution of the MoAbs was then determined and the effect of RIT on human colonic cancer was observed.

Results: The [(131)I]-labeled anti-CEA MoAbs had a specific distribution after injection. Tumor/non-tumor ratios for [(131)I]-labeled anti-CEA MoAbs were 10-20 times higher than [(131)I]-labeled IgG 96 h after injection. Thirty days after injection, significant inhibition of the volume and weight of tumor was observed in the treated mice compared with the control. The tumor growth inhibition rate of 3.1 mCi/kg CEA MoAbs group (LS180, LS174T, SW1116) was 47.8%-64.0%. This was 69.6%-78.6% in the 6.25 mCi/kg CEA MoAbs group, and 81.8%-86.2% in the 12.5 mCi/kg [(131)I]-labeled anti-CEA MoAbs group. The plasma CEA level was also lower in treated mice.

Conclusion: The results indicate that [(131)I]-labeled anti-CEA MoAbs can be effective in RIT on colonic cancers.