Cancer vaccines targeting carbohydrate antigens.

Cancer carbohydrate antigens have been surprisingly potent targets for immune recognition and attack by antibodies, both because of their abundance at the cell surface and their immunogenicity. Antibodies are ideally suited for eradicating pathogens from the bloodstream and from early tissue invasion. Passively administered and vaccine induced antibodies have accomplished this, eliminating circulating tumor cells and systemic or intraperitoneal micrometastases in a variety of preclinical models. A series of carbohydrate cancer cell-surface differentiation antigens have now been identified and synthesized. Antibodies against each can be induced in the majority of vaccinated patients using KLH conjugate vaccines with a potent saponin immunological adjuvant. Polyvalent vaccines will probably be required due to tumor cell heterogeneity, heterogeneity of the human immune response and the correlation between overall antibody titer against tumor cells and antibody effector mechanisms. Trials testing the clinical impact of these polyvalent vaccines in the adjuvant setting are planned for the near future.