Nanomedicine integrating the lipidic derivative of 5-fluorouracil,miriplatin and PD-L1 si RNA for enhancing tumor therapy

Immunosuppressive microenvironments present critical problems in clinical chemotherapy.To regulate the tumor immune microenvironment for enhancing antitumor effect,a combination of immune checkpoint inhibitors(ICIs)with chemotherapeutics has been applied clinically.In this study,miriplatin(MiPt),the lipidic derivative of 5-fluorouracil(Fu-OA),as well as the programmed death ligand 1(PD-L1)target si RNA(siPD-L1)were integrated into Lip-Pt/Fu@siPD-L1 nanoparticles(NPs)for chemo-immunotherapy.In vitro results showed that Lip-Pt/Fu@siPD-L1 NPs could exhibit effective siRNA gene silencing and promote the phagocytosis of tumor cells by macrophages.Furthermore,in vivo results revealed that LipPt/Fu@siPD-L1 NPs showed significantly higher anti-tumor efficiency than that of the physical mixing of Mi Pt,5-fluorouracil,and Lip@siPD-L1 NPs(delivery of siPD-L1 by liposomes).The best anti-tumor efficiency of Lip-Pt/Fu@siPD-L1 NPs resulted from the synergistic immunotherapeutic effects of Mi Pt and siPD-L1 based on the inhibition of CD47 expression and the downregulation of PD-L1 in tumor cells,which elicited a robust anti-tumor immune response through the activation of macrophage phagocytosis and immune checkpoint inhibition.The Lip-Pt/Fu@siPD-L1 NPs provide a potential strategy for tumor chemo-immunotherapy.