ISCOM® based vaccines for cancer immunotherapy

Immunostimulating complex (ISCOM(R)) vaccines are particulate antigen delivery vehicles composed of saponin, cholesterol, phospholipid and immunogen. Here we illustrate that ISCOM(R)-based vaccines represent an attractive modality for the development of anti-cancer vaccines. Using murine models and a model cancer antigen, ISCOM(R) vaccines were shown to induce potent CD8 T cell responses, to mediate protection in three different tumor models, to promote Th1-biased immunity, and to induce CD8 T cell responses in the absence of CD4(+) T cell help. The former three activities were also found to be substantially improved when the vaccine antigen was associated with the ISCOM(R) structure. Furthermore, the presence in vivo of pre-existing antibodies against the vaccine antigen did not inhibit CD8 T cell induction by the ISCOM(R) vaccine. Although vaccination was effective against challenge with vaccine-antigen expressing tumors, no activity against neighboring vaccine-antigen negative tumor cells was observed, indicating that determinant spreading or bystander activity does not lead to significant anti-cancer activity. (C) 2003 Elsevier Ltd. All rights reserved.