A Redox-responsive Prodrug Nanogel of TLR7/8 Agonist for Improved Cancer Immunotherapy

The existence of tumor immunosuppressive microenvironment (TIME) is the major determinant for the poor efficacy of current tumor immunotherapy. Tumor-associated macrophages (TAMs) tend to become tumor-promoting M2-like phenotype and hinder immune response in solid tumors. Repolarization of TAMs from M2 to anti-tumor M1 phenotype is robust for remodeling the TIME. Herein, we developed a redox-responsive nanogel as the delivery system of Toll-like receptor 7 and 8 (TLR7/8) agonist (R848) prodrug for potent cancer immunotherapy. The nanogel (denoted as R848-Gel) was obtained by emulsion polymerization of HSEMA and R848 prodrug (R848-HSEMA), whose size was appropriate 100 nm. R848-Gel could be internalized by macrophages and dendritic cells in vitro, and effectively repolarized M2 into M1 macrophages and promoted the maturation of antigen-presenting cells. In vivo study indicated that the R848-Gel showed a stronger tumor inhibitory effect and no drastic body weight change compared with free drug. Immune cell analysis after the treatment indicated that R848-Gel was helpful to activating the TIME. In summary, this study provides a simple but effective vehicle for R848 to improve cancer immunotherapy.

Automated summary

The existence of tumor immunosuppressive microenvironment (TIME) is the major determinant for the poor efficacy of current tumor immunotherapy. In this study, a redox-responsive nanogel was developed as a delivery system for a potent cancer immunotherapy drug, with promising results in repolarizing tumor-associated macrophages and activating the immune response.