NY‐CO‐58/KIF2C is overexpressed in a variety of solid tumors and induces frequent T cell responses in patients with colorectal cancer

NY‐CO‐58/KIF2C has been identified as a tumor antigen by screening antibody responses in patients with colorectal cancer. However, expression had not consequently been examined, and nothing was known about its ability to induce spontaneous T cell responses, which have been suggested to play a role in the development of colorectal cancer. We analyzed 5 colorectal cancer cell lines, and tumor samples and adjacent healthy tissues from 176 patients with epithelial cancers for the expression of NY‐CO‐58/KIF2C by RT‐PCR and Western Blot. T cell responses of 43 colorectal cancer patients and 35 healthy donors were evaluated by ELISpot following stimulation with 30mer peptides or full‐length protein. All cell lines and tumor samples from colorectal cancer patients expressed NY‐CO‐58/KIF2C on the protein and RNA level, and expression levels correlated strongly with Ki‐67 expression ( r = 0.69; p = 0.0003). Investigating NY‐CO‐58/KIF2C‐specific T cell responses, CD8 + T cells directed against 1 or more peptides were found in less than 10% of patients, whereas specific CD4 + T cells were detected in close to 50% of patients. These T cells were of high avidity, recognized the naturally processed antigen and secreted IFN‐γ and TNF‐α. Depletion of CD4 + CD25 + T cells before stimulation significantly increased the intensity of the preexisting response. NY‐CO‐58/KIF2C is significantly overexpressed in colorectal and other epithelial cancers and expression levels correlate with the proliferative activity of the tumor. Importantly, NY‐CO‐58/KIF2C was able to induce spontaneous CD4 + T cell responses of the Th1‐type, which were tightly controlled by peripheral T regulatory cells.