Cancer Vaccines: Promising Therapeutics or an Unattainable Dream

Abstract

The advent of cancer immunotherapy has revolutionized the field of cancer treatment and offers cancer patients new hope. Although this therapy has proved highly successful for some patients, its efficacy is not all encompassing and several cancer types do not respond. Cancer vaccines offer an alternate approach to promote anti-tumor immunity that differ in their mode of action from antibody-based therapies. Cancer vaccines serve to balance the equilibrium of the crosstalk between the tumor cells and the host immune system. Recent advances in understanding the nature of tumor-mediated tolerogenicity and antigen presentation has aided in the identification of tumor antigens that have the potential to enhance anti-tumor immunity. Cancer vaccines can either be prophylactic (preventative) or therapeutic (curative). An exciting option for therapeutic vaccines is the emergence of personalized vaccines, which are tailor-made and specific for tumor type and individual patient. This review summarizes the current standing of the most promising vaccine strategies with respect to their development and clinical efficacy. We also discuss prospects for future development of stem cell-based prophylactic vaccines.

Cancer Vaccines and Immunotherapy for Tumor Prevention and Treatment

“…Numerous challenges make cancer vaccination difficult, and two review articles in this Special Issue give insight into numerous immunological and technical challenges [4,6]. Development of prophylactic and therapeutic vaccines for cancer is far more challenging than developing vaccines against viral or bacterial diseases because of the limited antigenicity of cancer cells; immune evasion pathways that block T-cell activation, suppress the TME, and others; differences in ideal effector mechanisms to resist microbial pathogenesis (often antibodies) and eliminate cancer (often cytotoxic CD8 + T-cells); and many more.…”

“…Several review articles in this Special Issue emphasized how our understanding of antitumor immune responses has accelerated the identification of tumor antigens which may be recognized by endogenous antitumor immune responses and exploited as vaccine targets for cancer immunotherapy [4,6,9]. These review articles discuss several TAAs, including overexpressed antigens and differentiation antigens.…”

“…Overexpressed antigens such as mucin 1 (MUC1), HER2/neu, telomerase, and survivin are generally expressed at very low levels in normal cells, but their expression increases in tumor cells, producing an opportunity for targeting by vaccines. Normal differentiation antigens such as gp100 and prostatic acid phosphatase (PAP) are proteins that are normally expressed in differentiated tissues (melanocytes and prostate, respectively) and retained in cancers derived from those tissues (melanoma and prostate cancer, respectively) [6]. Although discoveries in genomics and proteomics have significantly accelerated the identification of tumor antigens in patients, identification of shared tumor antigens remains a challenge for many cancer types, leading to a need for identifying patient-specific tumor neoantigens, which may be a better approach to eradicate tumors by targeting immunogenic and/or driver mutations.…”

“…While vaccine strategies for cancer are inherently more challenging than those against viruses, cancers of viral origin [hepatitis B virus (HBV) and human papillomavirus (HPV)] provide an excellent opportunity for primary cancer prevention through viral-directed vaccines [6,10]. HBV and HPV infection, major viral causes of hepatocellular and cervical cancer, respectively, have been successfully prevented through FDA-approved vaccines [9].…”

“…Review articles in this issue reminded us how the recent SARS-CoV-2 pandemic has boosted awareness of vaccines to prevent communicable diseases and brought a renewed focus on cancer vaccines and improved vaccine technologies [4][5][6]. Renewed interest in vaccine technologies has accelerated scientific interest in using these technologies to design vaccines for cancer immunotherapy.…”