A unique gene having homology with the kinesin family member 18A encodes a tumour-associated antigen recognised by cytotoxic T lymphocytes from HLA-A2+ colon cancer patients

Colon cancer is one of the major malignant tumours for which the development of a new treatment modality is needed. To provide the scientific basis for a specific immunotherapy for colon cancer, we looked for tumour-associated antigens recognised by cytotoxic T lymphocytes (CTLs) from human leukocyte antigen (HLA)-A2+ colon cancer patients. We report here a unique gene, 3362 base-pairs (bp) long, which has homology with the kinesin family member 18A. This gene was expressed at the mRNA level in the majority of tumour cells, but not in any normal tissues tested except for testis and lung. Two of 16 peptides with HLA-A2-binding motifs were recognised by tumour-reactive CTLs. In addition, these two peptides had the ability to induce HLA-A2-restricted and cancer-reactive CTLs from peripheral blood mononuclear cells (PBMCs) of colon cancer patients with several HLA-A2 subtypes. Overall, this study provides new information about a colon cancer-related antigen that might be an appropriate target for specific immunotherapy in HLA-A2+ colon cancer patients.