A Novel Tri-Functional Liposome Re-Educates "Cold Tumor" and Abrogates Tumor Growth by Synergizing Autophagy Inhibition and PD-L1 Blockade

Immunotherapy has been regarded as a breakthrough in cancer treatment and achieved great success. However, the poor response rate is still a formidable challenge of current immunotherapies, especially in solid tumors without sufficient infiltration of immune cells, also known as "cold tumor." SAR405 is a highly specific VPS34 inhibitor and has been suggested as a potential approach converting "cold tumor" into "hot tumor" by inhibiting autophagy. In this study, a tri-functional doxorubicin (DOX) plus SAR405 liposome system is established and further modified with a novel anti-PD-L1 peptide JY4 for targeted delivery (DOX-SAR-JY4(LIPO)). The data here demonstrate that in a lung cancer xenograft mouse model, by facilitating the tumoral enrichment of both SAR405 and DOX, DOX-SAR-JY4(LIPO) effectively increases the infiltration of cytotoxic lymphocytes in the tumor by synergizing DOX-induced immunogenic cell death (ICD) and SAR405-mediated upregulation of chemokines including CCL5 and CXCL10. As results, DOX-SAR-JY4(LIPO) significantly inhibits tumor growth, metastasis, and resurrection by re-educating immunosuppressive tumor microenvironment. In conclusion, this study not only proves the concept of inhibiting autophagy for better immune infiltration in the tumor but also presents a novel tri-functional liposomal system that overcomes the deficiencies of current therapies and holds great promise in cancer immunotherapy.