Enhancement of anti-PD-1/PD-L1 immunotherapy for osteosarcoma using an intelligent autophagy-controlling metal organic framework

Poor immunogenicity and compromised T cell infiltration impede the application of immune-checkpoint blockade (ICB) immunotherapy for osteosarcoma (OS). Although autophagy is involved in enhancing the immune response, the synergistic role of autophagy in ICB immunotherapy and the accurate control of autophagy levels in OS remain elusive and challenging. Here, we designed a pH-sensitive autophagy-controlling nanocarrier, CUR-BMS1166@ZIF-8@PEG-FA (CBZP), loading a natural derivative, curcumin (CUR), to boost the immunotherapeutic response of PD-1/PD-L1 blockade by activating immunogenic cell death (ICD) via autophagic cell death, and BMS1166 to inhibit the PD-1/PD-L1 interaction simultaneously, enhancing the tumor immunogenicity and sensitizing the antitumor T cell immunity. After entering tumor cells, the pH-sensitive nanoparticles induced autophagy and decreased the intracellular pH, which in turn further facilitated the release of CUR to enhance autophagic activity. Transferring CBZP to orthotopic OS tumor-bearing mice showed powerful antitumor effects and established long-term immunity against tumor recurrence, accompanied by enhanced dendritic cell maturation and tumor infiltration of CD8+ T lymphocytes. Collectively, CBZP exhibited synergistic effects in treating OS by combining ICD induction with checkpoint blockade, thereby shedding light on the use of autophagy control as a potential clinical therapy for OS.