Photo-induced crosslinked and anti-PD-L1 peptide incorporated liposomes to promote PD-L1 multivalent binding for effective immune checkpoint blockade therapy

Immune checkpoint blockade(ICB)therapy targeting PD-L1 via monoclonal antibody(m Ab)has shown extensive clinical benefits in the diverse types of advanced malignancies.However,most patients are completely refractory to ICB therapy owing to the PD-L1 recycling mechanism.Herein,we propose photo-induced crosslinked and anti-PD-L1 peptide incorporated liposomes(immune checkpoint blockade liposomes;ICB-LPs)to promote PD-L1 multivalent binding for inducing lysosomal degradation of PD-L1 in tumor cells.The ICB-LPs are prepared by formulation of DC_(8,9)PC with photo-polymerized diacetylenic moiety,1,2-dipalmitoylphosphatidylcholine(DPPC)and anti-PD-L1peptide(D-form NYSKPTDRQYHF)-conjugated DSPE-PEG_(2k)(anti-PD-L1-DSPE-PEG_(2k))in a molar ratio of 45:45:10,followed by cross-linking of liposomal bilayer upon UV irradiation.The 10 mol% antiPD-L1-DSPE-PEG_(2k)incorporated ICB-LPs have a nano-sized lipid bilayer structure with an average diameter of 137.7±1.04 nm,showing a high stability in serum condition.Importantly,the ICB-LPs efficiently promote the multivalent binding with PD-L1 on the tumor cell membrane,which are endocytosed with aim to deliver PD-L1 to the lysosomes,wherein the durable PD-L1 degradation is observed for72 h,in contrast to anti PD-L1 m Abs showing the rapid PD-L1 recycling within 9 h.The in vitro coculture experiments with CD8^(+)T cells show that ICB-LPs effectively enhance the T cell-mediated antitumor immune responses against tumor cells by blocking the PD-L1/PD-1 axis.When ICB-LPs are intravenously injected into colon tumor-bearing mice,they efficiently accumulate within the targeted tumor tissues via both passive and active tumor targeting,inducing a potent T cell-mediated antitumor immune response by effective and durable PD-L1 degradation.Collectively,this study demonstrates the superior antitumor efficacy of crosslinked and anti-PD-L1 peptide incorporated liposome formulation that promotes PD-L1 multivalent binding for trafficking of PD-L1 toward the lysosomes instead of the recycling endosomes.

All-in-one glycol chitosan nanoparticles for co-delivery of doxorubicin and anti-PD-L1 peptide in cancer immunotherapy

Synergistic immunotherapy of immune checkpoint blockade (ICB) and immunogenic cell death (ICD) has shown remarkable therapeutic efficacy in various cancers. However, patients show low response rates and undesirable outcomes to these combination therapies owing to the recycling mechanism of programmed death-ligand 1 (PD-L1) and the systemic toxicity of ICD-inducing chemotherapeutic drugs. Herein, we propose all-in-one glycol chitosan nanoparticles (CNPs) that can deliver anti-PD-L1 peptide (PP) and doxorubicin (DOX) to targeted tumor tissues for a safe and more effective synergistic immunotherapy. The PP-CNPs, which are prepared by conjugating ᴅ-form PP (NYSKPTDRQYHF) to CNPs, form stable nanoparticles that promote multivalent binding with PD-L1 proteins on the targeted tumor cell surface, resulting in effective lysosomal PD-L1 degradation in contrast with anti-PD-L1 antibody, which induces recycling of endocytosed PD-L1. Consequently, PP-CNPs prevent subcellular PD-L1 recycling and eventually destruct immune escape mechanism in CT26 colon tumor-bearing mice. Moreover, the ICD inducer, DOX is loaded into PP-CNPs (DOX-PP-CNPs) for synergistic ICD and ICB therapy, inducing a large number of damage-associated molecular patterns (DAMPs) in targeted tumor tissues with minimal toxicity in normal tissues. When the DOX-PP-CNPs are intravenously injected into CT26 colon tumor-bearing mice, PP and DOX are efficiently delivered to the tumor tissues via nanoparticle-derived passive and active targeting, which eventually induce both lysosomal PD-L1 degradation and substantial ICD, resulting in a high rate of complete tumor regression (CR: 60%) by a strong antitumor immune response. Collectively, this study demonstrates the superior efficacy of synergistic immunotherapy using all-in-one nanoparticles to deliver PP and DOX to targeted tumor tissues.