Adjuvants in Cancer Vaccines - Progress and Challenges

Ever since the use of aluminium hydroxide (alum) as a potent adjuvant, there has been a colossal rise in the available adjuvants of varied nature for vaccine development. We now have come to a point where we know that some of the immune components such as cytokines are themselves associated with adjuvant properties. However, despite hundreds of well-designed pre-clinical candidates obtained after decades of research, only a handful of vaccine adjuvants have been approved and licensed for human use. This may be attributed to the complexity and the difficulty in designing adjuvants that are safe, potent and economically viable. However recent advances in our understanding of innate immunity, the immune response pathways and the mechanism of adjuvant interactions has led to better adjuvant formulations. For cancer, the success stories of treatment through immunotherapy were not as significant as that of chemo- or radiotherapy. However, vaccine development research has got an enormous attention after the US FDA approval of various preventive cancer vaccines such as Gardasil (Merck), Cervarix (Glaxosmithkline) and the therapeutic vaccine Sipulencel-T (Provenge). Approval of these vaccines has invigorated the use of cellular immunotherapy as an effective alternate method for the treatment of cancer and has provided support for renewed interest and attention which the development of new therapeutic cancer vaccines deserves. The present chapter discusses the role, mechanism of action, current clinical scenario of new cancer vaccine adjuvants, application of their molecularly defined formulations to new generation cancer vaccines and the future challenges, for the benefit of a varied audience.

Keywords: Adjuvant formulation, Alum, AS03, AS04, BCG, BSA, Cancer vaccine, Cellular response, CLRs, Cytokines, Dendritic cells, Humoral response, Immunotherapy, Immunization, Inflammasome, MF59, New generation vaccines, NLRs, Pattern recognition receptors, Potential adjuvants, TLRs, Virus-like particles.