Intramuscular immunisation with MUC1 cDNA can protect C57 mice challenged with MUC1-expressing syngeneic mouse tumour cells.

Much interest is currently being shown in immunotherapy as a treatment for cancer since several tumour-associated antigens have been identified and the genes encoding them cloned. One such molecule is the tumour-associated human MUC1 gene product. In this report we describe tumour rejection studies in a C57B1 murine model system with syngeneic MUC1-expressing tumour cells designed to examine the efficacy of MUC1 cDNA as an immunogen. Intra-muscular immunisation with 100 microgram MUC1 cDNA 3 times at 3-weekly intervals resulted in tumour protection in approximately 80% of mice. Tumour protection was dose-dependent, with 50-100 microgram being the most effective dose. Both humoral and cell-mediated MUC1-specific immune responses were detected. Anti-MUC1 antibodies were detected after immunisation with DNA alone, indicating that the injected DNA was expressed. Humoral immune responses did not correlate with tumour rejection. Tumour challenge with syngeneic tumour cells expressing MUC1 appeared to be a pre-requisite for the generation of MUC1-specific cytotoxic T lymphocytes.