Summary of Invention The present invention relates to a novel, diagnostic antigen for colorectal cancer, uses thereof, and especially the use thereof in immunotherapeutic treatments for colorectal cancer. Solution to which problem (s) Colon cancer is a leading cause of mortality in Western countries. Despite the improvement of surgery and chemotherapy treatments, the five-year survival rate has not significantly altered over several decades. Immunological therapies have been intensively investigated in patients with melanoma, where treatment with IL-2, as well as the adoptive transfer of in-vitro cultured tumor infiltrating lymphocytes (TIL), has been found to result in cancer regression in a significant percentage of patients. In contrast, immunotherapy has not provided a benefit to colorectal cancer patients, which may be due to the poor immunological characterization of this cancer, limiting the treatment options for patients with this disease.

The presence of a CD8+ T cell infiltrate in colon cancer has prognostic value; nevertheless, the presence of an inflammatory infiltrate was not linked to systemic immunity against cancer in this report. The loss of HLA class I expression both in vitro and in vivo has frequently been described in colorectal cancers, and appears to be associated with tumor progression. The limited availability of in-vitro established tumor lines and specific T lymphocytes has in addition hindered analysis of the role of the immune system in colorectal cancer. Although a large number of tumor associated antigens (TAA) have been identified, the majority of these are either limited in their expression to melanoma or are expressed in melanoma as well as in a number of other histologies, including breast, ovarian, lung and prostate tumors. Candidate antigens that appear to be over-expressed in colon cancer such as carcinoembryonic antigen (CEA), the epithelial cell adhesion molecule EP-CAM, HER-2/neu and cyclophilin B, have been evaluated as potential targets for colorectal cancer therapy by carrying out in vitro sensitizations of PBMC with candidate peptides from these molecules that bind to particular HLA alleles. However, a relatively small number of potential epitopes have been identified using this approach and the T cells that have been generated, using many of these peptides, did not efficiently recognise native, unmanipulated tumor cells. We have now identified a new tumor associated antigen for colorectal cancer that is capable of eliciting a T cell-mediated immune response. Key applications The present invention allows to: - a method for stimulating immunity against colorectal cancer by the use of an immunizing peptide comprising the epitope that can elicit a T cell-mediated reactivity against tumor cells. Stage of Development: The technology is in the preclinical stage and only in vitro studies have been completed. In vivo experiments are planned in animal models.

USA priority filing Oct. 15, 2003; recently extended to PCT - joint ownership with NIH.

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