Target Delivery siRNA Blockade Dual CD47 and PD-L1 Checkpoints Induced Innate and Adaptive Immune Responses

Treatment multiple tumors by immune therapy can be achieved by mobilizing both innate and adaptive immunity. The programmed death ligand 1 (PD-L1; or CD274, B7-H1) is a critical "don't find me" signal to the adaptive immune system. Equally CD47 is a critical "don't eat me" signal to the innate immune system and a regulator of the adaptive immune response. Both of them are overexpressed on the surface of cancer cells to enable to escape immune-surveillance. EpCAM (epithelial cell adhesion  molecule)-targeted cationic liposome (LPP-P4-Ep) contained si-CD47 and si-PD-L1 could knockdown both CD47 and PD-L1 proteins on PC-9 cells surface, and this multinanoparticles  versus single gene therapy showed significantly high-EpCAM tumor targeting and lower toxicity, and enhanced immune therapeutic efficacy. Efficient silencing of CD47 and PD-L1 in tumor tissues with systemic administration of LPP-P4-  Ep also significantly inhibited the growth of solid tumors. In a lung metastasis model,LPP-P4-Ep efficiently inhibited lung metastasis to 15% of the untreated control. Target  delivery of the complexes LPP-P4-Ep increased anti-tumor T cell and NK cell response, and release various cytokines including IFN-γ and IL-6 in vivo and in vitro. Our data indicated that dual-blockade tumor cell-specific innate and adaptive checkpoints represents an improved strategy for tumor immunotherapy. Funding Statement: This research was supported by the Ministry of Science and Technology of the People’s Republic of China (grant number 2015CB931804); the National Natural Science Foundation of China (NSFC, grant numbers 81703555, U1505225 and 81773063), and the China Postdoctoral Science Foundation (grant number 2017M620268). Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: All animal experiments were approved by the Institutional Animal Care and Use Committee of Fuzhou University and operated following the NSFC regulations concerning the care and use of experimental animals. The healthy blood collection procedure was carried out in accordance with the guidelines verified and approved by Fujian Provincial People's Hospital Affiliated. All donors signed an informed consent for scientific research statement.