Viral vector vaccines to treat colorectal cancer

Despite recent advances in the diagnosis and treatment of colorectal cancer, it remains the second commonest cause of cancer deaths in the USA. Current therapeutic agents have provided a small, incremental survival benefit at the cost of significantly increased toxicities. There is a huge unmet need for novel effective therapies. Colorectal cancer evades the host immune surveillance as a result of weak immunogenicity and immunosuppressive effects of cancer cells. Cancer vaccines have the potential to activate the immune system against colorectal cancer cells by increasing the expression and presentation of tumor-associated antigens. Recent clinical trials using viral-vector-based cancer vaccines have demonstrated clinical benefit with excellent safety profiles in patients with metastatic colorectal cancer. Here, we review the rationale for immunotherapy in colon cancer; clinical trial data for viral-vector-based colorectal cancer vaccines, the advantages and disadvantages of viral vectors, and future treatment strategies.