Induction of cellular immune responses to tumor cells and peptides in colorectal cancer patients by vaccination with SART3 peptides.

The tumor-rejection antigen SART3 possesses two antigenic epitopes (SART3(109-118) and SART3(315-323)) capable of inducing HLA-A24-restricted and tumor-specific CTLs. To determine its safety and ability to generate antitumor immune responses, 12 patients with advanced colorectal cancer were administered s.c. vaccinations of these peptides. No severe adverse events were associated with the vaccinations. Significant levels of increased cellular immune responses to both HLA-A24+ colon cancer cells and the vaccinated peptide were observed in the postvaccination peripheral blood mononuclear cells in 7 of 11 and 7 of 10 patients tested, respectively, and the higher responses were observed in those patients vaccinated with the highest dose (3 mg/injection) of the peptides. These results encourage further development of SART3 peptide vaccine for colorectal cancer patients.