Nanosonosensitizer-Augmented Sonodynamic Therapy Combined with Checkpoint Blockade for Cancer Immunotherapy

Int J Nanomedicine. 2021 Mar 5:16:1889-1899. doi: 10.2147/IJN.S290796. eCollection 2021.

Abstract

Introduction: Sonodynamic therapy (SDT) has good targeting and non-invasive advantages in the treatment of solid cancers, and checkpoint blockade immunotherapy is also a promising treatment to cure cancer. However, their antitumor effects are not sufficient due to some inherent factors. Some studies that combined SDT with immunotherapy or nanoparticles have managed to enhance its efficiency to treat cancers.

Methods: In this work, an effective therapeutic strategy that can potentiate the antitumor efficacy of anti-PD-L1 antibody (aPD-L1) is developed by the use of cascade immuno-sonodynamic therapy (immuno-SDT). Titanium dioxide (TiO2), a nanostructured agent for SDT, sonosensitizer Chlorin e6 (Ce6), and immunological adjuvant CpG oligonucleotide (CpG ODN), are used to construct a multifunctional nanosonosensitizer (TiO2-Ce6-CpG). Then, we conducted in vitro and in vivo experiments to explore the antitumor effect of TiO2-Ce6-CpG under ultrasound (US) treatment.

Results: The characterization tests showed that the nanosonosensitizers are polycrystalline structure with homogeneous sizes, resulting in a good drug loading efficiency. The innovative nanosonosensitizers (TiO2-Ce6-CpG) can not only effectively inhibit tumor growth but also stimulate the immune system to activate the adaptive immune responses, using the TiO2-Ce6 to augment SDT and the immune adjuvant CpG to enhance the immune response. After combined with the aPD-L1, the synergistic effect could not only efficiently inhibit the primary tumor growth but also lead to an inhibition of the non-irradiated pre-existing distant tumors by inducing a strong tumor-specific immune response.

Conclusion: In this study, we present an effective strategy for tumor treatment by combining nanosonosensitizer-augmented SDT and aPD-L1 checkpoint blockade. This work provides a promising strategy and offers a new vision for treating malignant tumors.

Keywords: cancer immunotherapy; checkpoint blockade; sonodynamic therapy; sonosensitizer; titanium dioxide nanoparticles.

MeSH terms

  • Animals
  • Cell Death / drug effects
  • Cell Line, Tumor
  • Chlorophyllides
  • Combined Modality Therapy
  • Dendritic Cells / drug effects
  • Endocytosis / drug effects
  • Female
  • Humans
  • Immune Checkpoint Inhibitors / pharmacology
  • Immune Checkpoint Inhibitors / therapeutic use*
  • Immunity / drug effects
  • Immunotherapy*
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Nanoparticles / chemistry*
  • Nanoparticles / ultrastructure
  • Neoplasms / immunology*
  • Neoplasms / pathology
  • Neoplasms / therapy*
  • Oligodeoxyribonucleotides / chemistry
  • Porphyrins / chemistry
  • Reactive Oxygen Species / metabolism
  • Titanium / chemistry
  • Ultrasonic Therapy*

Substances

  • CPG-oligonucleotide
  • Chlorophyllides
  • Immune Checkpoint Inhibitors
  • Oligodeoxyribonucleotides
  • Porphyrins
  • Reactive Oxygen Species
  • titanium dioxide
  • phytochlorin
  • Titanium