Radioimmunotherapy of Human Colon Cancer in Nude Mice

• Nude mice bearing subcutaneous human colon cancer xenografts (LS174T) were treated with 120 μCi of yttrium 90—labeled anti-carcinoembryonic antigen monoclonal antibodies (specific therapy), 120 μCi of⁹⁰Y-labeled anti-melanoma monoclonal antibodies (nonspecific therapy), or phosphate-buffered saline solution (no treatment control). Mean (±SD) tumor growth rates (percent increase per day) over the first 30 days of the study were as follows: 0.6%±0.2% per day (specific therapy); 17.7%±5.7% per day (nonspecific therapy); and 30.5%±4.2% per day (control). In all three groups, tumors over 1 g had similar doubling times (5.74±0.71 d). Specific therapy caused a lag in tumor growth corresponding to a 3-logarithm cell kill. Estimated tumor dose of radiation obtained by tissue analysis was 34 and 14 Gy for specific and nonspecific therapy, respectively. In conclusion, 120 μCi of⁹⁰Y-labeled anti-carcinoembryonic antigen monoclonal antibodies was effective in suppressing growth of human colon cancer xenografts. Clinical studies with this preparation are recommended.

(Arch Surg. 1990;125:660-664)