Project description:Direct activation of tumor infiltrating antigen-presenting cells (APCs) by intratumoral injection of STING agonists (STINGa) leads to regression of the treated lymphoma tumor. Because STING activation induces apoptosis in lymphoma cells in vitro, we distinguished between the direct therapeutic vs the indirect immunotherapeutic properties of STINGa in vivo. Employing wild-type or STING knockout hosts bearing either wild-type or STING knockout tumor cells, we demonstrated that local tumor regression is totally dependent on STING expression by the host and is therefore immune mediated. However, distant untreated tumors are weakly affected after injection of STINGa to a single tumor site. Therefore, using the STINGa currently being tested in clinical trials, we screened for immunomodulatory agents that could synergize with the STING pathway to induce a systemic antitumor immune response and regression of distant tumors. We combined the STINGa with agents that improve APC or T-cell function. We found that modulation of both APCs and T cells can enhance control of distant lymphoma tumors by STINGa. In particular, adding an anti-GITR antibody induced lymphocyte expansion in the lymph node draining the treated site followed by increased T-cell infiltration in the distant tumor. Furthermore, more of these CD8 T cells at the distant site expressed PD-1. Therefore, blockade of PD-1 further enhanced tumor control at the distant site, leading to cure in 50% of the mice. These preclinical data provide the rationale for testing local injection of STINGa followed by agonistic anti-GITR and anti-PD-1 antibodies as immunotherapy for human lymphoma.
Project description:Cyclic dinucleotides (CDNs), such as c-di-GMP (CDG), are agonists for stimulator of interferon genes (STING) and are promising for cancer immunotherapy. Yet, the therapeutic efficacy of CDNs has been limited by poor delivery and biostability. Here, STING-activating DNA nanovaccines (STING-NVs) are developed, which biostabilize, deliver, and conditionally release CDG in the endosome of immune cells, elicit potent antitumor immune responses in murine and human immune cells, ameliorate immunosuppression in vitro and in the tumor microenvironment, and mediate potent cancer immunotherapy in a murine melanoma model. STING-NVs have PLA-b-PEG in the core and cytosine (C)-rich i-motif DNA on the surface. i-Motif DNA undergoes characteristic pH-responsive conformational switch, allowing efficient CDG loading via C:G base pairing at physiological pH, and CDG release in sensitive response to acidic environment such as cell endosome. STING-NVs protect CDG from enzymatic degradation. STING-NVs facilitate cell delivery. Remarkably, STING-NVs promote the endosome escape of CDG by ninefold, and potentiate antitumor immunity. STING-NVs repolarize immunosuppressive M2-like macrophages into antitumor M1-like macrophages in vitro and in the tumor microenvironment of melanoma. In a poorly immunogenic murine melanoma model, intralesional STING-NVs outperform liposomal CDG and fluoride-CDG for melanoma immunotherapy. These results suggest the great potential of STING-NVs for cancer immunotherapy.
Project description:Nanozymes and cyclic GMP-AMP synthase (cGAS) the stimulator of interferon genes (STING) signaling pathway, as powerful organons, can remodel the tumor microenvironment (TME) to increase efficacy and overcome drug resistance in cancer immunotherapy. Nanozymes have the potential to manipulate the TME by producing reactive oxygen species (ROS), which lead to positive oxidative stress in tumor cells. Cyclic dinucleotide (2',3'-cGAMP), as a second messenger, exists in the TME and can regulate it to achieve antitumor activity. In this work, Co,N-doped carbon dots (CoNCDs) were used as a model nanozyme to evaluate the properties of the anti-tumor mechanism, and effective inhibition of S180 tumor was achieved. Based on CoNCDs' good biocompatibility and therapeutic effect on the tumor, we then introduced the cGAS-STING agonist, and the combination of the CoNCDs and STING agonist significantly inhibited tumor growth, and no significant systemic toxicity was observed. The combined system achieved the enhanced tumor synergistic immunotherapy through TME reprogramming via the peroxidase-like activity of the CoNCDs and cGAS-STING signaling pathway agonist synergistically. Our work provides not only a new effective way to reprogram TME in vivo, but also a promising synergic antitumor therapy strategy.
Project description:Immune checkpoint blockade (ICB) has significantly advanced cancer immunotherapy, yet its patient response rates are generally low. Vaccines, including immunostimulant-adjuvanted peptide antigens, can improve ICB. The emerging neoantigens generated by cancer somatic mutations elicit cancer-specific immunity for personalized immunotherapy; the novel cyclic dinucleotide (CDN) adjuvants activate stimulator of interferon genes (STING) for antitumor type I interferon (IFN-I) responses. However, CDN/neoantigen vaccine development has been limited by the poor antigen/adjuvant codelivery. Here, pH-responsive CDN/neoantigen codelivering nanovaccines (NVs) for ICB combination tumor immunotherapy are reported. pH-responsive polymers are synthesized to be self-assembled into multivesicular nanoparticles (NPs) at physiological pH and disassembled at acidic conditions. NPs with high CDN/antigen coloading are selected as NVs for CDN/antigen codelivery to antigen presenting cells (APCs) in immunomodulatory lymph nodes (LNs). In the acidic endosome of APCs, pH-responsive NVs facilitate the vaccine release and escape into cytosol, where CDNs activate STING for IFN-I responses and antigens are presented by major histocompatibility complex (MHC) for T-cell priming. In mice, NVs elicit potent antigen-specific CD8+ T-cell responses with immune memory, and reduce multifaceted tumor immunosuppression. In syngeneic murine tumors, NVs show robust ICB combination therapeutic efficacy. Overall, these CDN/neoantigen-codelivering NVs hold the potential for ICB combination tumor immunotherapy.
Project description:Therapeutic cancer vaccines require adjuvants leading to robust type I interferon and proinflammatory cytokine responses in the tumor microenvironment to induce an anti-tumor response. Cyclic dinucleotides (CDNs), a potent Stimulator of Interferon Receptor (STING) agonist, are currently in phase I trials. However, their efficacy may be limited to micromolar concentrations due to the cytosolic residence of STING in the ER membrane. Here we utilized biodegradable, poly(beta-amino ester) (PBAE) nanoparticles to deliver CDNs to the cytosol leading to robust immune response at >100-fold lower extracellular CDN concentrations in vitro. The leading CDN PBAE nanoparticle formulation induced a log-fold improvement in potency in treating established B16 melanoma tumors in vivo when combined with PD-1 blocking antibody in comparison to free CDN without nanoparticles. This nanoparticle-mediated cytosolic delivery method for STING agonists synergizes with checkpoint inhibitors and has strong potential for enhanced cancer immunotherapy.
Project description:Recently, nanovaccine-based immunotherapy has been robustly investigated due to its potential in governing the immune response and generating long-term protective immunity. However, the presentation of a tumor peptide-major histocompatibility complex to T lymphocytes is still a challenge that needs to be addressed for eliciting potent antitumor immunity. Type 1 conventional dendritic cell (cDC1) subset is of particular interest due to its pivotal contribution in the cross-presentation of exogenous antigens to CD8+ T cells. Here, the DC-derived nanovaccine (denoted as Si9GM) selectively targets cDC1s with marginal loss of premature antigen release for effective stimulator of interferon genes (STING)-mediated antigen cross-presentation. Bone marrow dendritic cell (BMDC)-derived membranes, conjugated to cDC1-specific antibody (αCLEC9A) and binding to tumor peptide (OVA257-264), are coated onto dendrimer-like polyethylenimine (PEI)-grafted silica nanoparticles. Distinct molecular weight-cargos (αCLEC9A-OVA257-264 conjugates and 2'3'-cGAMP STING agonists) are loaded in hierarchical center-radial pores that enables lysosome escape for potent antigen-cross presentation and activates interferon type I, respectively. Impressively, Si9GM vaccination leads to the upregulation of cytotoxic T cells, a reduction in tumor regulatory T cells (Tregs), M1/M2 macrophage polarization, and immune response that synergizes with αPD-1 immune checkpoint blockade. This nanovaccine fulfills a dual role for both direct T cell activation as an artificial antigen-presenting cell and DC subset maturation, indicating its utility in clinical therapy and precision medicine.
Project description:The cGAS-STING pathway is essential for immune defense against microbial pathogens and malignant cells; as such, STING is an attractive target for cancer immunotherapy. However, systemic administration of STING agonists poses safety issues while intratumoral injection is limited by tumor accessibility. Here, we generated antibody-drug conjugates (ADCs) by conjugating a STING agonist through a cleavable linker to antibodies targeting tumor cells. Systemic administration of these ADCs was well tolerated and exhibited potent antitumor efficacy in syngeneic mouse tumor models. The STING ADC further synergized with an anti-PD-L1 antibody to achieve superior antitumor efficacy. The STING ADC promoted multiple aspects of innate and adaptive antitumor immune responses, including activation of dendritic cells, T cells, natural killer cells and natural killer T cells, as well as promotion of M2 to M1 polarization of tumor-associated macrophages. These results provided the proof of concept for clinical development of the STING ADCs.
Project description:The Stimulator of Interferon Genes (STING) pathway is a promising target for cancer immunotherapy. Despite recent advances, therapies targeting the STING pathway are often limited by routes of administration, suboptimal STING activation, or off-target toxicity. Here, we report a dendritic cell (DC)-targeted polymeric prodrug platform (polySTING) that is designed to optimize intracellular delivery of a diamidobenzimidazole (diABZI) small-molecule STING agonist while minimizing off-target toxicity after parenteral administration. PolySTING incorporates mannose targeting ligands as a comonomer, which facilitates its uptake in CD206+/mannose receptor+ professional antigen-presenting cells (APCs) in the tumor microenvironment (TME). The STING agonist is conjugated through a cathepsin B-cleavable valine-alanine (VA) linker for selective intracellular drug release after receptor-mediated endocytosis. When administered intravenously in tumor-bearing mice, polySTING selectively targeted CD206+/mannose receptor+ APCs in the TME, resulting in increased cross-presenting CD8+ DCs, infiltrating CD8+ T cells in the TME as well as maturation across multiple DC subtypes in the tumor-draining lymph node (TDLN). Systemic administration of polySTING slowed tumor growth in a B16-F10 murine melanoma model as well as a 4T1 murine breast cancer model with an acceptable safety profile. Thus, we demonstrate that polySTING delivers STING agonists to professional APCs after systemic administration, generating efficacious DC-driven antitumor immunity with minimal side effects. This new polymeric prodrug platform may offer new opportunities for combining efficient targeted STING agonist delivery with other selective tumor therapeutic strategies.
Project description:Most non-muscle invasive bladder cancers have been treated by transurethral resection and following intravesical injection of immunotherapeutic agents. However, the delivery efficiency of therapeutic agents into bladder wall is low due to frequent urination, which leads to the failure of treatment with side effects. Here, we report a urease-powered nanomotor containing the agonist of stimulator of interferon genes (STING) for the efficient activation of immune cells in the bladder wall. After characterization, we perform in vitro motion analysis and assess in vivo swarming behaviors of nanomotors. The intravesical instillation results in the effective penetration and retention of nanomotors in the bladder. In addition, we confirm the anti-tumor effect of nanomotor containing the STING agonist (94.2% of inhibition), with recruitment of CD8+ T cells (11.2-fold compared with PBS) and enhanced anti-tumor immune responses in bladder cancer model in female mice. Furthermore, we demonstrate the better anti-tumor effect of nanomotor containing the STING agonist than those of the gold standard Bacille Calmette-Guerin therapy and the anti-PD-1 inhibitor pembrolizumab in bladder cancer model. Taken together, the urease-powered nanomotor would provide a paradigm as a next-generation platform for bladder cancer immunotherapy.
Project description:Recently, cancer immunotherapy has received attention as a viable solution for the treatment of refractory tumors. However, it still has clinical limitations in its treatment efficacy due to inter-patient tumor heterogeneity and immunosuppressive tumor microenvironment (TME). In this study, we demonstrated the triggering of anti-cancer immune responses by a combination of irreversible electroporation (IRE) and a stimulator of interferon genes (STING) agonist. Optimal electrical conditions inducing damage-associated molecular patterns (DAMPs) by immunogenic cell death (ICD) were determined through in vitro 2D and 3D cell experiments. In the in vivo syngeneic lung cancer model, the combination of IRE and STING agonists demonstrated significant tumor growth inhibition. We believe that the combination strategy of IRE and STING agonists has potential for effective cancer immunotherapy.