Modulating barriers of tumor microenvironment through nanocarrier systems for improved cancer immunotherapy: a review of current status and future perspective

Cancer immunotherapy suppresses and destroys tumors by re-activating and sustaining the tumor-immune process, and thus improving the immune response of the body to the tumor. Immunotherapeutic strategies are showing promising results in pre-clinical and clinical trials, however, tumor microenvironment (TME) is extremely immunosuppressive. Thus, their translation from labs to clinics still faces issues. Recently, nanomaterial-based strategies have been developed to modulate the TME for robust immunotherapeutic responses. The combination of nanotechnology with immunotherapy potentiates the effectiveness of immunotherapy by increasing delivery and retention, and by reducing immunomodulation toxicity. This review aims to highlight the barriers offered by TME for hindering the efficiency of immunotherapy for cancer treatment. Next, we highlight various nano-carriers based strategies for modulating those barriers for achieving better therapeutic efficacy of cancer immunotherapy with higher safety. This review will add to the body of scientific knowledge and will be a good reference material for academia and industries.