Cancer vaccines and immunotherapies: emerging perspectives.

Research efforts over the last two decades studying immune responses to human carcinomas have demonstrated that antigens expressed by tumor cells can elicit specific cellular and humoral immune responses. Unfortunately, despite the observation that existent immune responses to these antigens are present in some patients with cancer, the tumors continue to progress. Thus, there has been considerable interest to augment these immune responses by immunization. Some of the clinical trials of the first cancer vaccines have provided evidence of clinical benefit thus encouraging the development of other vaccines. Challenges to development of such cancer vaccines include the identification and characterization of the antigen(s) to be targeted, the definition of the desired immune response to be elicited by the vaccine, and the choice of the appropriate vaccine delivery system.