Nanotechnology-based multifunctional vaccines for cancer immunotherapy

Cancer immunotherapy including cancer vaccines, immune checkpoint blockade or chimeric antigen receptor T cells has been considered a promising cancer terminator, which can direct the patient's own immune system to specifically fight against this challenging disease. Cancer immunotherapy involved the "cancer immunity cycle", which mainly includes the following steps: specific tumor antigen identification, lymph node-targeted antigen/adjuvant co-delivery, antigen internalization and release, as well as antigen cross-presentation to T cells. However, the widespread implementation of cancer immunotherapy still faces several challenges, for instance, life-threatening off-target side effects, long processing time, inadequate cytotoxic T lymphocyte response due to immunosuppressive tumor microenvironment, and high cost. Multifunctional nanovaccine based on nanotechnology, which can be designed to efficiently deliver tumor antigens and adjuvants to activate antigen-presenting cells and induce specific antitumor immune responses, is uniquely suited to overcome these challenges involved in the "cancer immunity cycle". In this review, we summarized the nanovaccines that have been used to overcome the obstacles of nanotechnology-based cancer immunotherapy. In order to achieve more effective cancer suppression and elimination in the future, we also provide challenges and perspectives associated with cancer immunotherapy and nanovaccine design of this emerging field.