Developments in anticancer vaccination: budding new adjuvants.

The immune system has a limited capacity to recognize and fight cells that become cancerous and in cancer patients, the immune system has to seek the right balance between cancer rejection and host-immunosupression. The tumor milieu builds a protective shell and tumor cells rapidly accumulate mutations that promote antigen variability and immune-escape. Therapeutic vaccination of cancer is a promising strategy the success of which depends on a powerful activation of the cells of the adaptive immune system specific for tumor-cell detection and killing (e.g. CD4+ and CD8+ T-cells). In the last decades, the search for novel adjuvants that enhance dendritic cell (DC) function and their ability to prime T-cells has flourished and some Toll-like receptor (TLR) agonists have long been known to be valid immune adjuvants. The implementation of TLR-synthetic agonists in clinical studies of cancer vaccination is replacing the initial use of microbial-derived products with some encouraging results. The purpose of this review is to summarize the latest discoveries of TLR-synthetic agonists with adjuvant potential in anti-cancer vaccination.