Cancer vaccine adjuvants – recent clinical progress and future perspectives

Abstract

Despite recent breakthroughs in the prognosis, prevention and treatment, cancer still remains the leading cause of death and affects millions of people worldwide. With the US FDA approval of various preventive cancer vaccines such as Gardasil (Merck), Cervarix (Glaxosmithkline) and the therapeutic vaccine Sipulencel-T (Provenge), cancer vaccine development is gaining huge ground. Approval of these vaccines has encouraged the concept of cancer treatment through cellular immunotherapy. The FDA approval of the above vaccines has provided support for renewed interest and attention which the development of new therapeutic cancer vaccines deserves. However, most of the new generation vaccines including that for cancer are poorly immunogenic sub-unit vaccines and thus essentially need adjuvants in their formulations to compensate for the immune suppression. Adjuvants are the essential components of a potent vaccine which increases the efficacy by enhancing the antigen-specific immune response. However, the design of a successful adjuvant is not easy because of the complexity and the difficulty in designing adjuvants that are safe, potent and economically viable. The present communication takes a short review of the advancements in adjuvant technology, current clinical scenario of new adjuvants and application of their molecularly defined formulations to new generation cancer vaccines which are currently under development.

Polymeric micro/nanoparticles: Particle design and potential vaccine delivery applications

“…For example, the first Food and Drug Administration (FDA)-approved tumor vaccine (Provenge) could suppress metastatic castration-resistant prostate cancer by activating the power of the patient's own immune system [6]. A crucial requirement for therapeutic vaccine is to elicit sufficient cellular immune responses against the target cells, thus not only the strength but also the polarization of the immune response should be considered in adjuvant design, making it even more challenging [7]. Development of vaccines requires safe and efficient adjuvant or antigen delivery systems.…”

Cancer immunoprevention

“…), as well as immunostimulatory substances known as adjuvants. There has been a lot of progress in developing new delivery vehicles and adjuvants[53] but very few have been components of FDA approved vaccines that have been administered to large numbers of adults or children to provide a track record of acceptable toxicity. Those that have been used in vaccines against pathogens by and large induce type 2 immunity, which is not considered the most appropriate for anti-cancer vaccines.…”

Nanomaterials for cancer immunotherapy

“…They will induce highly focused, specific responses with low reactogenicity. Because of this, subunit antigens lack intrinsic innate and/or adaptive immune triggers, thus necessitating the inclusion of adjuvants [63, 64]. …”