Nanoassembly of doxorubicin-conjugated polyphosphoester and siRNA simultaneously elicited macrophage- and T cell- mediated anticancer immune response for cancer therapy

Efficiently reawakening immune cells, including T cells and macrophages, to eliminate tumor cells is a promising strategy for cancer treatment, but remains a huge challenge nowadays. Herein, a nanoassembly formed by doxorubicin (DOX)-conjugated polyphosphoester (PP-(hDOX)) and CD47-targeting siRNA (siCD47) via electrostatic and π-π stacking interactions, termed as PP-(hDOX&siCD47), was developed to reawaken the T cell and macrophage-mediated anticancer activity. The PP-(hDOX&siCD47) could efficiently blockade antiphagocytic signal by downregulation of CD47 expression to reactive macrophage-mediated anticancer immunotherapy. Moreover, the conjugated DOX of PP-(hDOX&siCD47) can perform the chemotherapy towards tumor cells and also elicit the T cell-mediated anticancer immune response via immunogenic cell death (ICD) effect. Therefore, the PP-(hDOX&siCD47) treatment could significantly increase M1-like macrophages proportion and tumor infiltration of CD8+ T cells, while the proportions of regulatory T cells (Treg) and myeloid-derived suppressor cells (MDSC) were considerably reduced in tumor tissue, eventually achieving significantly tumor growth inhibition. Overall, this study provides a simple siRNA and DOX codelivery approach to simultaneously elicit the macrophage- and T cell-mediated anticancer immune response for cancer therapy.