Successful radioimmunotherapy for lung metastasis of human colonic cancer in nude mice.

The potential for radioimmunotherapy as an adjuvant treatment for early disseminated colonic cancer was investigated in an experimental lung metastasis model. Nude mice receiving intravenous injection with a suspension of human colonic cancer cells (GW-39) developed multiple (10-100) tumor nodules throughout the lungs, and more than 50% of the animals died of extensive tumor involvement within 5-10 weeks. Groups of eight or nine animals bearing 7-day-old tumor transplants were treated with a single intravenous injection of radioiodinated agents: either 0.15 or 0.30 mCi of whole IgG of the NP-4 murine monoclonal antibody (MAb) against carcinoembryonic antigen (CEA) or 0.15 or 0.30 mCi of whole IgG of Immu-31, an anti-alpha-fetoprotein (anti-AFP) MAb. Treatment of animals with 0.15 or 0.30 mCi of 131I-labeled NP-4 IgG 7 days after injection of tumor cells resulted in survival for 23 weeks after tumor implantation in four of eight and seven of nine animals, respectively. Microscopic examination revealed that over 90% of the lung tumor colonies had no evidence of surviving cells. Animals treated with 0.30 mCi of anti-AFP, an irrelevant MAb, survived 4 weeks longer than controls. Toxicity was evident in four of the 17 animals given 0.30 mCi of NP-4 IgG (specific) or anti-AFP IgG (irrelevant) MAb. These animals died within 1-3 weeks after radioantibody injection, suggesting that death was related to the radiation dose. None of the animals given 0.15 mCi of 131I-MAb died within this period.(ABSTRACT TRUNCATED AT 250 WORDS)