Metronomic Doses of Temozolomide Enhance the Efficacy of Carbon Nanotube CpG Immunotherapy in an Invasive Glioma Model

PLoS One. 2016 Feb 1;11(2):e0148139. doi: 10.1371/journal.pone.0148139. eCollection 2016.

Abstract

Even when treated with aggressive current therapies, most patients with glioblastoma survive less than two years. Rapid tumor growth, an invasive nature, and the blood-brain barrier, which limits the penetration of large molecules into the brain, all contribute to the poor tumor response associated with conventional therapies. Immunotherapy has emerged as a therapeutic approach that may overcome these challenges. We recently reported that single-walled carbon nanotubes (SWCNTs) can be used to dramatically increase the immunotherapeutic efficacy of CpG oligonucleotides in a mouse model of glioma. Following implantation in the mouse brain, the tumor cell line used in these previous studies (GL261) tends to form a spherical tumor with limited invasion into healthy brain. In order to evaluate SWCNT/CpG therapy under more clinically-relevant conditions, here we report the treatment of a more invasive mouse glioma model (K-Luc) that better recapitulates human disease. In addition, a CpG sequence previously tested in humans was used to formulate the SWCNT/CpG which was combined with temozolomide, the standard of care chemotherapy for glioblastoma patients. We found that, following two intracranial administrations, SWCNT/CpG is well-tolerated and improves the survival of mice bearing invasive gliomas. Interestingly, the efficacy of SWCNT/CpG was enhanced when combined with temozolomide. This enhanced anti-tumor efficacy was correlated to an increase of tumor-specific cytotoxic activity in splenocytes. These results reinforce the emerging understanding that immunotherapy can be enhanced by combining it with chemotherapy and support the continued development of SWCNT/CpG.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology
  • Antineoplastic Agents / therapeutic use
  • Brain Neoplasms / drug therapy*
  • Brain Neoplasms / pathology
  • Cell Death / drug effects
  • Cell Line, Tumor
  • Dacarbazine / analogs & derivatives*
  • Dacarbazine / therapeutic use
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Female
  • Glioma / drug therapy*
  • Glioma / pathology
  • Immunotherapy*
  • Inflammation / pathology
  • Lipids / chemistry
  • Mice, Inbred C57BL
  • Nanotubes, Carbon / chemistry*
  • Neoplasm Invasiveness
  • Oligodeoxyribonucleotides / therapeutic use*
  • Polyethylene Glycols / chemistry
  • Spleen / pathology
  • Temozolomide
  • Treatment Outcome

Substances

  • Antineoplastic Agents
  • CPG-oligonucleotide
  • Lipids
  • Nanotubes, Carbon
  • Oligodeoxyribonucleotides
  • Polyethylene Glycols
  • Dacarbazine
  • Temozolomide