Mesoporous Silica as a Versatile Platform for Cancer Immunotherapy.

Immunotherapy has been recognized for decades as a promising therapeutic method for cancer treatment. To enhance host immune responses against cancer, antigen-presenting cells (APCs; e.g., dendritic cells) or T cells are educated using immunomodulatory agents including tumor-associated antigens and adjuvants, and manipulated to induce a cascading adaptive immune response targeting tumor cells. Mesoporous silica materials are promising candidates to improve cancer immunotherapy based on their attractive properties that include high porosity, high biocompatibility, facile surface modification, and self-adjuvanticity. Here, the recent progress on mesoporous-silica-based immunotherapies based on two material forms is summarized: 1) mesoporous silica nanoparticles (MSNs), which can be internalized into APCs, and 2) micrometer-sized mesoporous silica rods (MSRs) that can form a 3D space to recruit APCs. Subcutaneously injected MSN-based cancer vaccines can be taken up by peripheral APCs or by APCs in lymphoid organs to educate the immune system against cancer cells. MSR cancer vaccines can recruit immune cells into the MSR scaffold to induce cancer-specific immunity. Both vaccine systems successfully stimulate the adaptive immune response to eradicate cancer in vivo. Thus, mesoporous silica has potential value as a material platform for the treatment of cancer or infectious diseases.