The principal objective of this review article was to discuss the advantages, limitations, and present challenges of anticancer peptide-based vaccines. Many new therapies are currently being used to treat cancer. Peptide-based chemotherapy has been of great interest due to the unique advantages of peptides, such as low molecular weight, the ability to specifically target tumor cells, and low toxicity in normal tissues. In treating cancer, peptide-based chemotherapy can be mainly divided into three types: peptide-alone therapy, peptide-based vaccines, and peptide-conjugated nanomaterials. Peptide-based vaccines have been used in advanced cancers to improve patient’s overall survival. The combination of peptides with nanomaterials expands the therapeutic ability of peptides to treat cancer by enhancing drug delivery and sensitivity. Immune recognition and elimination of cancerous cells are the primary goals of cancer immunotherapy. However, obstacles, including immune tolerance and tumor-induced immunosuppression, often limit beneficial immune responses. Vaccination is one proposed intervention that may help to overcome these issues and is an active area of study in cancer immunotherapy. Immunizing with tumor antigenic peptides is a promising vaccine strategy, hypothesized to boost pre-existing antitumor immunity. However, tumor antigens are often weak T cell agonists, attributable to several mechanisms, including immune self-tolerance and poor immunogenicity of self-derived tumor peptides. One strategy for overcoming these mechanisms is vaccination with mimotopes, which alter the antigen presentation and/or T cell activation. Peptide-based vaccines incorporate one or more short or long amino acid sequences as tumor antigens, combined with a vaccine adjuvant. Thus, they fall broadly into the category of defined-antigen vaccines, along with vaccines using protein, protein subunits, DNA, or RNA.
Current comprehensive cancer care is focused on reducing the bulk of disease through surgery, chemotherapy, and radiation. Despite the increasing effectiveness of these cornerstones of treatment and high cure rates of multiple cancer forms, cancer remains a leading cause of death. Recent breakthroughs in cancer immunotherapy have added several promising new therapies to the traditional armamentarium of oncology treatment regimens. The strategy of utilizing the immune system in the treatment of cancer dates back to the 1890s and the work of William Coley. Coley observed that some tumors regress in the setting of acute bacterial infection. He attempted to recapitulate this phenomenon by studying the injection of heat-inactivated Streptococcus erysipelas and Serratia marcescens (Coley’s toxins) in cancer patients. The field of cancer immunology and immunotherapy had greatly advanced since Coley’s initial studies, a time when little was known about the mechanisms underlying the antitumor effects of bacterial toxins. There is now a growing understanding of how the immune system identifies tumor cells and targets them for elimination. Just as important is the growing understanding of how tumors can undermine the immune system’s ability to recognize and eliminate cancer cells. Briefly, an adaptive immune response against tumor cells is classically believed to be initiated when tissue-resident antigen-presenting cells, such as dendritic cells, take up and process tumor-specific or tumor-associated antigens, and present these antigens in the context of major histocompatibility complex (MHC) complexes to naïve T-cells in secondary lymphoid organs.