Anti-tumor vaccines in head and neck cancer: targeting immune responses to the tumor.

Immune therapies aiming at the destruction of a residual tumor and inducing tumor-specific memory responses are gaining acceptance among clinicians treating head and neck squamous cell carcinoma (HNSCC). This solid tumor lends itself remarkably well to currently popular vaccination strategies. Immune suppression is a hallmark of HNSCC, and its reversal accompanied by the vaccine-mediated restoration of antitumor immunity might be a promising approach to achieving improved survival of HNSCC patients. To date, few antitumor vaccines for HNSCC have been clinically evaluated. The reasons for this slow start are discussed, and the ongoing phase I clinical vaccination trials for HNSCC patients are briefly described. The emphasis is on dendritic cell (DC)-based vaccines, largely because of enhanced immunogenicity of epitopes presented by adoptively-transferred DC to responder T cells in vivo. Delivery of such antitumor vaccines in combination with conventional therapies and in the setting of a minimal residual disease to HNSCC patients takes advantage of exquisite specificity of the immune system at the time when tumor-induced suppression is reduced. Vaccine-driven generation, long-term survival and maintenance of tumor-specific immune cells are the objectives that antitumor vaccines have to realize to be clinically beneficial in HNSCC.