Oncolytic virotherapy in glioblastoma patients induces a tumor macrophage phenotypic shift leading to an altered glioblastoma microenvironment

Neuro Oncol. 2018 Oct 9;20(11):1494-1504. doi: 10.1093/neuonc/noy082.


Background: Immunosuppressive protumoral M2 macrophages are important in pathogenesis, progression, and therapy resistance in glioblastoma (GBM) and provide a target for therapy. Recently oncolytic virotherapy in murine models was shown to change these M2 macrophages toward the pro-inflammatory and antitumoral M1 phenotype. Here we study the effects of the oncolytic virotherapy Delta24-RGD in humans, using both in vitro models and patient material.

Methods: Human monocyte-derived macrophages were co-cultured with Delta24-RGD-infected primary glioma stem-like cells (GSCs) and were analyzed for their immunophenotype, cytokine expression, and secretion profiles. Cerebrospinal fluid (CSF) from 18 Delta24-RGD-treated patients was analyzed for inflammatory cytokine levels, and the effects of these CSF samples on macrophage phenotype in vitro were determined. In addition, tumor macrophages in resected material from a Delta24-RGD-treated GBM patient were compared with 5 control GBM patient samples by flow cytometry.

Results: Human monocyte-derived M2 macrophages co-cultured with Delta24-RGD-infected GSCs shifted toward an M1-immunophenotype, coinciding with pro-inflammatory gene expression and cytokine production. This phenotypic switch was induced by the concerted effects of a change in tumor-produced soluble factors and the presence of viral particles. CSF samples from Delta24-RGD-treated GBM patients revealed cytokine levels indicative of a pro-inflammatory microenvironment. Furthermore, tumoral macrophages in a Delta24-RGD-treated patient showed significantly greater M1 characteristics than in control GBM tissue.

Conclusion: Together these in vitro and patient studies demonstrate that local Delta24-RGD therapy may provide a therapeutic tool to promote a prolonged shift in the protumoral M2 macrophages toward M1 in human GBM, inducing a pro-inflammatory and potentially tumor-detrimental microenvironment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brain Neoplasms / immunology
  • Brain Neoplasms / pathology*
  • Brain Neoplasms / therapy
  • Cytokines / metabolism
  • Glioblastoma / immunology
  • Glioblastoma / pathology*
  • Glioblastoma / therapy
  • Humans
  • Immunophenotyping
  • Macrophages / immunology
  • Macrophages / pathology*
  • Neoplastic Stem Cells / immunology
  • Neoplastic Stem Cells / pathology*
  • Oncolytic Virotherapy*
  • Oncolytic Viruses / immunology*
  • Tumor Cells, Cultured
  • Tumor Microenvironment / immunology*
  • Virus Replication


  • Cytokines