Peptide Delivery Systems for Cancer Vaccines

Cancer vaccines aim to activate the immune system so it can seek and eradicate cancer cells. Peptide vaccines hold the minimalistic amount of biochemical information required for generating antigen-specific T cells to elicit anticancer responses. Unfortunately, results from most peptide cancer vaccine large clinical trials have been underwhelming. This may stem from a number of reasons, such as tumor-mediated immunosuppression, limited T cell-tumor infiltration, or insufficient T cell numbers induced in response to the vaccine. On their own, immunization with naked peptides usually does not induce a satisfactory response, so adjuvants and/or delivery systems are required. Beyond the traditional aluminum salts, oil emulsions, and carrier protein conjugates, next generation peptide delivery systems hold potential to induce stronger or broader responses that could eventually provide for improved immunotherapy outcomes. This review summarizes recent approaches to peptide cancer vaccines, in the context of emerging delivery systems.