GSH-activable and cytolytic iPep-coupled immune nanoagonist for cancer synergetic therapy

Integrating an oncotic immunogenic cell death (ICD) inducer with TLR agonists to facilitate chemo-immunotherapy presents a promising avenue for addressing cancer treatment. While each agent shown remarkable potential in eliciting immune responses individually, the synergistic capabilities of oncotic chemotherapeutics in combination with TLR agonists remain an uncharted area of research. Herein, to prevent the occurrence of off-target systemic inflammatory side effects associated with the TLR7/8 agonist, the reactive amino group of Resiquimod (R848) was covalently linked to human serum albumin (HSA) via a glutathione (GSH)-activatable linker, thereby establishing a series of R848-HSA conjugates. Specifically, RS-HSA (with an R848: HSA ratio of 1.6:1, n/n) was assembled with an oncotic membrane-active peptide (iPep) to form iP-RS NPs, which exhibited reduced toxicity and synergistic effects in modulating the tumor immunosuppressive microenvironment, disrupting the surrounding desmoplastic stroma, and enhancing anti-tumor immunity. The iP-RS NPs demonstrated satisfactory chemo-immune effects, achieving complete tumor regression in orthotopic 4T1 breast tumor mice and subcutaneous Panc02 pancreatic tumor mice. Furthermore, iP-RS NPs achieved successful treatment in three out of five mice harboring a clinically relevant and challenging orthotopic model of fLuc-KPC pancreatic ductal adenocarcinoma (PDAC), leading to a significant prolongation of their survival. In stark contrast, the first-line treatment regimen of Gemcitabine + Nab-paclitaxel offered only a marginal survival extension of less than a week when compared to the PBS control group. Our findings underscore the promising prospects of combining oncotic therapeutics with TLR7/8 agonists, with a rational design aimed at minimizing the toxicity of the TLR agonist while achieving superior synergistic therapeutic efficacy.