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.