Systemic cancer therapy with a small molecule agonist of toll-like receptor 7 can be improved by circumventing TLR

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Carole Bourquin1, Christian Hotz, Daniel Noerenberg

  • 1Department of Internal Medicine, Ludwig-Maximilian University of Munich, Munich, Germany. carole.bourquin@med.lmu.de

Cancer Research
|June 24, 2011
PubMed

Insights

Repeated systemic Toll-like receptor 7 (TLR7) agonist injections can cause immune tolerance, hindering cancer therapy. A new intermittent dosing strategy circumvents this tolerance, improving immunotherapy efficacy in preclinical models.

Area of Science:

  • Immunology
  • Cancer Biology
  • Pharmacology

Background:

  • Systemic Toll-like receptor 7 (TLR7) agonists show promise for cancer therapy but face challenges due to immune tolerance.
  • Repeated TLR7 stimulation can lead to hyporesponsiveness, inhibiting crucial cytokine production and impairing anti-tumor immune responses.

Purpose of the Study:

  • To investigate the mechanisms underlying TLR7 tolerance after systemic administration.
  • To develop and evaluate a novel dosing strategy to overcome TLR7 tolerance for improved cancer immunotherapy.

Main Methods:

  • Systemic administration of the TLR7 agonist R848 in mice.
  • Analysis of cytokine secretion (IL-12p70, IL-6, IFN-α) and dendritic cell function.
  • Evaluation of a novel intermittent dosing protocol in a CT26 tumor-bearing mouse model.

Main Results:

  • Single R848 injection induced transient hyporesponsiveness, characterized by suppressed IL-12p70, IL-6, and IFN-α production.
  • TLR7 tolerance was observed in both plasmacytoid and myeloid dendritic cells, with reduced IL-1 receptor-associated kinase 1 in plasmacytoid dendritic cells.
  • Intermittent R848 dosing successfully circumvented TLR7 tolerance and enhanced anti-tumor immunotherapy efficacy.

Conclusions:

  • Systemic TLR7 agonist administration can induce immune tolerance mediated by dendritic cell dysfunction.
  • A novel intermittent dosing strategy effectively overcomes TLR7 tolerance.
  • This approach holds potential for improving the efficacy of cancer immunotherapy.

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