ABSTRACT

INTRODUCTION Therapeutic vaccination for cancer continues to be a major approach to the overall immunotherapy of cancer. Historically, interest in cancer immunology stemmed from the perceived potential activity of the immune system as a weapon against cancer cells. In fact, the term ‘‘magic bullet,’’ commonly used to describe many visions of cancer therapy, was coined by Paul Erlich in the late 1800s in reference to antibodies targeting both microbes and tumors. Central to the concept of successful cancer immunotherapy are the dual tenets that tumor cells express an antigenic profile distinct from their normal cellular counterparts and that the immune system is capable of recognizing these antigenic differences. Support for this notion originally came from animal models of carcinogen-induced cancer in which it was demonstrated that a significant number of experimentally induced tumors could be rejected upon transplantation into syngeneic immunocompetent animals (1-4). Extensive studies by Prehn on the phenomenon of tumor rejection suggested that the most potent tumor rejection antigens were unique to the individual tumor (5).