Recent progress in nanomaterials for nucleic acid delivery in cancer immunotherapy

The combination of gene therapy and immunotherapy has the potential to systemically promote anti-tumor effects while reducing adverse reactions. Small interfering RNA (siRNA) has generated great interest in biology, engineering and medicine, especially for cancer treatment due to its ability to knock down genes of interest. Nanomaterials play significant roles in the design of delivery systems of siRNA, and nanomaterial-mediated siRNA delivery in cancer immunotherapy is one of the most important directions for future clinical cancer treatment. Here, we review the recent advances in nanomaterial mediated targeted delivery of siRNA to dendritic cells (DCs), tumor-associated macrophages (TAMs), immune checkpoint inhibitors, B lymphocytes, natural killer cells (NKs), and immunosuppressive cytokines. Fundamental challenges in nucleic acid delivery enabled by bio-barriers, its promising solution strategies and future directions are also reviewed.