Artikel
Targeted delivery of a toll-like receptor 3 agonist for immunotherapy of glioblastoma multiforme
Spezifischer Transfer eines TLR3-Agonisten zur Immuntherapie des Glioblastoma multiforme
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Autoren
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Alexander Hagstotz
- Universitätsklinikum Carl Gustav Carus Dresden, Neurochirurgie, Dresden, Deutschland
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Gabriele Schackert
- Universitätsklinikum Carl Gustav Carus Dresden, Neurochirurgie, Dresden, Deutschland
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Achim Temme
- Universitätsklinikum Carl Gustav Carus Dresden, Neurochirurgie, Dresden, Deutschland
| Veröffentlicht: | 4. Juni 2021 |
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Gliederung
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Objective: Glioblastoma multiforme (GBM) represents the most common primary adult brain tumor. Despite surgical resection followed by radiotherapy and chemotherapy, these tumors ultimately recur. One promising strategy for the treatment of GBM is immunotherapy. Yet, several vaccination approaches as well as adoptive transfer of tumor-reactive lymphocytes revealed disappointing responses due to immunosuppressive mechanisms of GBM. Thus far, agonists for toll-like receptors (TLRs) appear promising to reprogram the immunosuppressive environment of GBM. Yet, systemic treatment with TLR agonists is limited due to off-target effects. We sought to develop a selective delivery system for TLR3 agonists for treatment of GBM. Therefore, we designed immunoconjugate-nanoparticles (IC-NPs) for targeting exclusively astrocytoma/GBM cells with surface expression of oncogenic EGFRvIII.
Methods: For assembly of EGFRvIII-specific IC-NPs mono-biotinylated scFv(MR1.1)-P-BAP was conjugated to (neutr)avidin and mono-biotinylated 50bp dsRNA (TLR3 agonist). The specific endosomal localization of anti-EGFRvIII-IC-NPs in murine EGFRvIII-positive cells was examined by confocal microscopy (CM). Endosomal activation of TLR3 and the consecutive release of proinflammatory cytokines, chemokines, and type 1 interferons was analyzed via cytokine-specific multiplex bead-based flow cytometry. The immunotherapeutic anti-tumor effects of EGFRvIII-specific IC-NPs were investigated employing the syngeneic immunocompetent SMA-560/VM-Dk mouse model.
Results: The receptor-specific endocytosis and endosomal localization of anti-EGFRvIII-IC-NPs in EGFRvIII-expressing murine anaplastic astrocytoma cells (SMAvIII) was confirmed by CM. Furthermore, upon anti-EGFRvIII-IC-NP treatment the release of type 1 interferons, chemokines, and proinflammatory cytokines in SMAvIII followed a dose-dependent manner. Serial intraperitoneal application of anti-EGFRvIII-IC-NP tumors led to significant regression of subcutaneous SMAvIII tumors, and prolonged overall survival compared to PBS-treated controls.
Conclusion: Our results demonstrate the feasibility of IC-NPs for targeted delivery of TLR3 agonists to murine astrocytoma. Furthermore the IC-NP-mediated induction of innate and adaptive immune responses holds promises to improve immunotherapy of GBM.
