Cancer immunotherapy: moving forward with peptide T cell vaccines

- Cancer vaccines have not generated effective anti-tumor responses due to suboptimal immunogenicity.
- Peptide vaccines with appropriate adjuvants are the most promising strategy to induce tumor-reactive T cells and treat cancer.
- The combination of optimized peptides, strong adjuvants and costimulatory molecule stimulation together with systemic immunizations results in robust T cell responses.
- Therapeutic peptide-based vaccines can reduce the tumor growth by generating tumor-specific CD8 CTLs or CD4 HTLs.
- Blocking the immunosuppressive tumor microenvironment potentiates the effectiveness of cancer vaccines.

Recent advances in cancer immunology, such as the discovery of immune checkpoint inhibitors, have validated immune cells as potential key players for effective cancer treatment. The efficacy of these therapies seems to be codependent on a tumor-reactive T lymphocyte response. For many years, numerous attempts and strategies in developing vaccines to generate tumor-reactive T cells have yielded poor results in the clinic due to suboptimal immunogenicity and the inability to overcome an immunosuppressive tumor microenvironment. In this review, we summarize past and current advances in T cell vaccines and describe our experience in developing optimized methods for antigen/adjuvant selection and vaccine administration in order to induce powerful anti-tumor responses.