Polymer nanoparticles as adjuvants in cancer immunotherapy

Immunotherapy is a promising strategy to inhibit cancer progression via activation of the immune system. In immunotherapy, adjuvants as immunologic stimulants or delivery systems play a critical role in inducing the antitumor immune response and decreasing the side effects of immune stimulants. Polymer nanoparticles have attracted increasing attention as an indispensable component of immunotherapy, owing to their favorable properties, such as excellent biocompatibility and biodegradability, flexible size, high activity as immune stimulants, large surface area for binding multivalent immune ligands, and high loading capacity for immune-related components. In cancer immunotherapy, polymer nanoparticles can protect cargo from the surrounding milieu, deliver the antigens and immunostimulatory molecules to antigen-presenting cells, or stimulate robust T cell response. This review summarizes the current advancements in polymer nanoparticle adjuvants for cancer immunotherapy and predicts their prospects in fundamental and clinical studies.