Extending genetic vaccines with chemokines

B-cell malignancies as a model for cancer vaccines: from prototype protein to next generation genetic chemokine fusions

B-cell malignancy-derived Ig may be considered a model tumor antigen for vaccine development. However, as a non-immunogenic self antigen, it must also be first rendered immunogenic by chemical or genetic fusion to carriers which enable the induction of protective antitumor immunity in murine tumor models. Our group has demonstrated that active immunizations of human patients with idiotypic vaccines elicited antigen-specific CD8+ T-cell responses and antitumor effects. Several alternative preclinical strategies to develop vaccines have been previously reported, including fusion of tumor idiotype-derived single chain Fv with cytokines and immunogenic peptides. On the other hand, we have recently explored a different approach in which the model antigen is rendered immunogenic in mice by genetically fusing it to a chemokine moiety. Administration of these vaccines as fusion proteins or naked DNA vaccines may allow efficient targeting of antigen-presenting cells in vivo. Potent antitumor immunity was dependent on the generation of specific anti-idiotypic antibodies and both CD4+ and CD8+ effector T cells. We propose that chemokine fusion may represent a novel, general strategy for formulating existing or newly identified tumor and HIV antigens into vaccines for cancer and AIDS, respectively, which elicit potent CD8+ T-cell immunity.