Biomimetic Sonodynamic Therapy-Nanovaccine Integration Platform Potentiates Anti-PD-1 Therapy In Hypoxic Tumors

Immune checkpoint blockade（ICB）therapy,has emerged as novel therapeutic modalities for hard-to-treat solid tumors.However,inadequate T cell infiltration in hypoxic solid tumors has limited their anticancer efficacy.Therefore,the combination of other therapeutic modalities which can relieve tumor hypoxia and induce T cell infiltration into tumors is an optimal strategy for improved clinical outcomes of PD-1 antibody therapy.Cancer vaccines that deliver tumor-associated antigens to dendritic cells（DCs）and consequently activate T cells can induce substantial tumor-specific immunity,providing a promising approach to amplify the therapeutic efficacy of ICB to exert robust antitumor responses.Sonodynamic therapy（SDT）generates reactive oxygen species（ROS）by using the powerful penetrating ability of ultrasound（US）irradiation to activate sonosensitizers to kill cancer cells.Moreover,SDT has been reported to induce immunogenic cell death（ICD）and activate antitumor immunity as an in situ tumor vaccine.However,the insufficient tumor targeting of sonosensitizers and the improper tumor microenvironment,such as hypoxia and high glutathione（GSH）restrict SDT effects.Therefore,it is highly desirable to develop a suitable sonosensitizer with the self-sufficiency of O₂,GSH decreasing and tumor targeting capacity to synergistically increase ROS levels,improving the therapeutic effects of SDT and enhancing antitumor immunity.In this work,the sonosensitizer manganese porphyrin-based metal-organic framework（Mn-MOF）with the characteristics of catalase-like activity and decreasing intracellular GSH is synthesized and then binds with an immune adjuvant Cp G,followed by coating with cell membranes derived from ovalbumin（OVA）-overexpressing melanoma B16 cells（B16-OVA cells）.cMn-MOF@CM with prolonged blood circulation and enhanced tumor targeting efficiently relieves tumor hypoxia and generates strong SDT effects and elicit a strong tumor-specific immune response.Importantly,the combination of cMn-MOF@CM-triggered SDT and anti-PD-1 antibody induces stronger systemic immune response and long-term immunological memory function to prevent tumor growth and recurrence.The main research contents and results of this paper are as follows:（1）The preparation and characterization of cMn-MOF@CMMn-MOF with the characteristics of self-producing O₂ and decreasing intracellular GSH is synthesized and then binds with an immune adjuvant Cp G,followed by coating with cell membranes derived from OVA-overexpressing melanoma B16 cells to prepare cMn-MOF@CM.Transmission electron microscopy（TEM）and dynamic light scattering（DLS）analysis showed that cMn-MOF@CM had a diameter of about 121.1 nm and zeta potential of about-25.93 m V.In vitro characterization showed that binding with Cp G and cell membrane coating did not affect the capacity of Mn-MOF to catalyze H₂O₂ to produce O₂,decrease GSH and generate ROS under hypoxia upon US irradiation.（2）In vitro antitumor activity and immunity induced by cMn-MOF@CM upon US irradiationcMn-MOF@CM showed specific targeting ability to homologous cells.cMn-MOF@CM could efficiently decrease intracellular GSH content and produce ROS upon US irradiation under hypoxia to kill B16-OVA cells.cMn-MOF@CM induced ICD effects in B16-OVA cells upon US irradiation,eliciting a strong tumor-specific immune response by promoting DC maturation and T cell activation in combination of the immune adjuvant Cp G.Moreover,cMn-MOF@CM itself acting as a nanovaccine,efficiently activated the anti-tumor immune response by inducing DC maturation and CTL activation.（3）CM@cMn-MOF exertes excellent anti-tumor efficacy and activates antitumor immunity upon US irradiation in vivo.CM@cMn-MOF efficiently prolonged blood circulation and enhanced targeting to B16-OVA tumors to relieve tumor hypoxia.cMn-MOF@CM effectively inhibited tumor growth,prolonged the survival time of B16-OVA tumor-bearing mice upon US irradiation without significant side effects in unilateral and bilateral B16-OVA tumor-bearing mice.cMn-MOF@CM could elicit a strong tumor-specific immune response by promoting DC maturation and T cell activation as well as reprogramming the tumor immunosuppressive microenvironment.Meanwhile,the number of effector memory CD8⁺T cells significantly increased in spleens and tumor draining lymph nodes and prevent tumor formation after tumor re-challenge.（4）Combination of cMn-MOF@CM with US irradiation and anti-PD-1 antibody exerts synergistic antitumor efficacyCM@cMn-MOF increased PD-1 expression in CD8⁺T cells and PD-L1 expression in tumor cells of B16-OVA tumor bearing mice upon US irradiation.Combination of cMn-MOF@CM with US irradiation and anti-PD-1 antibody generated the strongest anticancer activity in unilateral and bilateral B16-OVA tumor-bearing mice,induced stronger systemic immune response and long-term immunological memory function to prevent tumor relapse.In summary,cMn-MOF@CM with high tumor targeting was developed to efficiently integrate SDT-nanovaccine synergistic platform for potentiating PD-1 antibody therapy in solid tumors therapy,which provideds a new strategy for tumor therapy.