Throughout the past 3 decades, along with the recognition that the immune system not only influences
oncogenesis and
tumor progression, but also determines how established neoplastic lesions respond
therapy, renovated enthusiasm has gathered around the possibility of using
vaccines as
anticancer agents. Such an enthusiasm quickly tempered when it became clear that anticancer
vaccines would have to be devised as therapeutic, rather than prophylactic, measures, and that malignant cells often fail to elicit (or actively suppress) innate and adaptive immune responses. Nonetheless, accumulating evidence indicates that a variety of anticancer
vaccines, including cell-based,
DNA-based, and purified component-based preparations, are capable of circumventing the poorly immunogenic and highly immunosuppressive nature of most
tumors and elicit (at least under some circumstances) therapeutically relevant immune responses. Great efforts are currently being devoted to the identification of strategies that may provide anticancer
vaccines with the capacity of breaking immunological tolerance and eliciting
tumor-associated
antigen-specific immunity in a majority of patients. In this sense, promising results have been obtained by combining anticancer
vaccines with a relatively varied panels of adjuvants, including multiple immunostimulatory
cytokines,
Toll-like receptor agonists as well as inhibitors of immune checkpoints. One year ago, in the December issue of OncoImmunology, we discussed the biological mechanisms that underlie the
antineoplastic effects of
peptide-based
vaccines and presented an abundant literature demonstrating the prominent clinical potential of such an approach. Here, we review the latest developments in this exciting area of research, focusing on high-profile studies that have been published during the last 13 mo and clinical trials launched in the same period to evaluate purified
peptides or full-length
proteins as therapeutic
anticancer agents.