Efficient tumor synergistic chemoimmunotherapy by self-augmented ROS-responsive immunomodulatory polymeric nanodrug

Immunotherapy has emerged as a promising therapeutic strategy for cancer therapy. However, the therapeutic efficacy has been distracted due to poor immunogenicity and immunosuppressive tumor microenvironment. In this study, a self-augmented reactive oxygen species (ROS) responsive nanocarrier with immunogenic inducer paclitaxel (PTX) and indoleamine 2,3-dixoygenase 1 (IDO1) blocker 1-methyl-D, L-tryptophan (1-MT) co-entrapment was developed for tumor rejection. The carrier was composed of poly (ethylene glycol) (PEG) as hydrophilic segments, enzyme cleavable 1-MT ester and ROS-sensitive peroxalate conjugation as hydrophobic blocks. The copolymer could self-assemble into prodrug-based nanoparticles with PTX, realizing a positive feedback loop of ROS-accelerated PTX release and PTX induced ROS generation. Our nanoparticles presented efficient immunogenic cell death (ICD) which provoked antitumor immune responses with high effector T cells infiltration. Meanwhile immunosuppressive tumor microenvironment was simultaneously modulated with reduced regulatory T cells (Tregs) and M2-tumor associated macrophages (M2-TAMs) infiltration mediated by IDO inhibition. The combination of PTX and 1-MT achieved significant primary tumor regression and reduction of lung metastasis in 4T1 tumor bearing mice. Therefore, the above results demonstrated co-delivery of immunogenic inducer and IDO inhibitor using the ROS amplifying nanoplatform with potent potential for tumor chemoimmunotherapy.