Nanosized drug delivery systems modulate the immunosuppressive microenvironment to improve cancer immunotherapy.

Immunotherapy that activates immune systems for combating cancer has yielded considerable clinical benefits recently. However, the immunosuppressive tumor microenvironment (ITME) is a major hurdle to immunotherapy as it supports tumor to evade immune surveillance. Reversing ITME facilitates the recruitment and activation of antitumor immune cells, thereby promoting immunotherapy. Our group has developed various nanosized drug delivery systems (NDDSs) to modulate ITME with enhanced efficacy and safety. In the review we introduce the ITME-remodeling strategies for improving immunotherapy based on NDDSs including triggering tumor cells to undergo immunogenetic cell death (ICD), applying tumor vaccine, and directly regulating intratumoral immune components (immune cells or cytokines). In order to guide the design of NDDSs for amplified effects of antitumor immunotherapy, the contributions and future directions of this field are also discussed.