Peptide Vaccines for Treatment of Colon Cancer: Have We Made Progress?

Colorectal cancer (CRC) is the third most common cancer diagnosis and cause of cancer-related death in the USA. It accounts for more than one million cases diagnosed each year worldwide. In the past 10 years, new drugs have been approved, but the survival times are still modest. Alternative therapeutic strategies are clearly needed. A large number of tumor antigens and epitopes recognized by cytotoxic T lymphocytes (CTLs) have been identified in CRC. Cancer vaccines, designed to activate immune effectors (T cells and antibodies), to prevent recurrence, or to treat advanced cancers, have demonstrated clinical benefit in melanoma, prostate cancer, and lymphoma. Immunotherapy that targets tumor-associated antigens (TAAs) on cancer cells or tumor stroma is under investigation. This review discusses CRC immune responsiveness, current status of CRC vaccines, challenges, and future directions. New therapeutic modalities hold a promise to improve the patient’s clinical outcome.