Optimized Peptide Vaccines Eliciting Extensive CD8 T Cell Responses with Therapeutic Anti-Tumor Effects

摘要

A major challenge for developing effective therapeutic vaccines against cancer is overcoming immunological tolerance to tumor-associated antigens that are expressed on both malignant cells and normal tissues. Herein, we describe a novel vaccination approach, TriVax that utilizes synthetic peptides representing CD8 T cell epitopes, Toll-like receptor (TLR) agonists that function as a potent immunological adjuvants and costimulatory anti-CD40 antibodies to generate large numbers of high avidity antigen-reactive T cells capable of recognizing and killing tumor cells. Our results show that TriVax induced huge numbers of long-lasting antigen specific CD8 T cells that displayed significant anti-tumor effects in vivo. The administration of a TriVax formulation containing a CD8 T cell epitope derived from a melanosomal antigen (Trp2180-188) elicited antigen-specific CD8 T cells that induced systemic autoimmunity (vitiligo). More important, TriVax immunization was effective in eliciting potent protective anti-tumor immunity as well as remarkable therapeutic effects against established B16 melanoma. This therapeutic effect was mediated by CD8 T cells via perforin-mediated lysis and required the participation of type I-IFN but not IFNγ. These results suggest that similar strategies would be applicable for the design of effective vaccination for conducting clinical studies in cancer patients.