Hybrid Drug Delivery System Designed from Spatiotemporal Hierarchical Controlled-Release Strategy Co-Delivering Rutin and Resveratrol for Coordinated Anti-Tumor Immunotherapy

Background: The highly heterogeneous and dynamically evolving tumor microenvironment leads to the development of drug resistance and recurrence in traditional therapies. Although immunotherapy demonstrates unique advantages, its clinical utility remains constrained by the suboptimal immunogenicity and the limited effect of monotherapy. Herein, a hybrid drug delivery system based on a spatiotemporal hierarchical controlled-release strategy was proposed to achieve dual immunotherapy with immune checkpoint blockade (ICB) and immunogenic cell death (ICD) to promote synergistic anti-tumor therapy. Methods: A liposome–micelle hybrid drug delivery system (RUT-RPP-LP) was constructed using a lipid bilayer composed of dioleoyl phosphatidylethanolamine/hemisuccinyl cholesterol to encapsulate rutin (RUT) and to form an inner cavity-encapsulated resveratrol micelle (RPP). RUT-RPP-LP was characterized, and its pH sensitivity and release behavior were investigated. Subsequently, a colon cancer tumor-bearing mouse model was constructed to evaluate the in vivo targeted anti-tumor effect and biological safety. On this basis, the combined mechanism of ICB and ICD was preliminarily explored. Results: RUT-RPP-LP possessed excellent formulation characteristics, stability, and biocompatibility, achieving graded controlled release of drugs via responding to the TME and lysosomal acidity, respectively. Obviously, RUT-RPP-LP could specifically target the tumor site, induce the occurrence of ICD, and simultaneously block the PD-1/PD-L1 immune checkpoint signaling pathway, thereby enhancing the function of T cells and inducing apoptosis of tumor cells. Conclusions: The RUT-RPP-LP based on the hierarchical controlled-release strategy exerted a spatiotemporally coordinated enhancement of anti-tumor immunity, and may provide a novel combinatorial approach to overcome the low response of immunotherapy in solid tumors.