Oncolytic HSV therapy increases trametinib access to brain tumors and sensitizes them in vivo

Ji Young Yoo, Jessica Swanner, Yoshihiro Otani, Mitra Nair, Flora Park, Yeshavanth Banasavadi-Siddegowda, Joseph Liu, Alena Cristina Jaime-Ramirez, Bangxing Hong, Feng Geng, Deliang Guo, Darlene Bystry, Mitch Phelphs, Haroon Quadri, Tae Jin Lee, Balveen Kaur

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)


Background: Hyperactivation of the RAS-RAF-MEK-ERK signaling pathway is exploited by glioma cells to promote their growth and evade apoptosis. MEK activation in tumor cells can increase replication of ICP34.5-deleted herpes simplex virus type 1 (HSV-1), but paradoxically its activation in tumor-associated macrophages promotes a pro-inflammatory signaling that can inhibit virus replication and propagation. Here we investigated the effect of blocking MEK signaling in conjunction with oncolytic HSV-1 (oHSV) for brain tumors. Methods: Infected glioma cells co-cultured with microglia or macrophages treated with or without trametinib were used to test trametinib effect on macrophages/microglia. Enzyme-linked immunosorbent assay, western blotting, and flow cytometry were utilized to evaluate the effect of the combination therapy. Pharmacokinetic (PK) analysis of mouse plasma and brain tissue was used to evaluate trametinib delivery to the CNS. Intracranial human and mouse glioma-bearing immune deficient and immune competent mice were used to evaluate the antitumor efficacy. Result: Oncolytic HSV treatment rescued trametinib-mediated feedback reactivation of the mitogen-activated protein kinase signaling pathway in glioma. In vivo, PK analysis revealed enhanced blood-brain barrier penetration of trametinib after oHSV treatment. Treatment by trametinib, a MEK kinase inhibitor, led to a significant reduction in microglia- and macrophage-derived tumor necrosis factor alpha (TNFα) secretion in response to oHSV treatment and increased survival of glioma-bearing mice. Despite the reduced TNFα production observed in vivo, the combination treatment activated CD8+ T-cell mediated immunity and increased survival in a glioma-bearing immune-competent mouse model. Conclusion: This study provides a rationale for combining oHSV with trametinib for the treatment of brain tumors.

Original languageEnglish
Pages (from-to)1131-1140
Number of pages10
Issue number9
Publication statusPublished - Sept 6 2019
Externally publishedYes


  • Glioblastoma (GBM)
  • Oncolytic herpes simplex virus-1 (oHSV)
  • RAS-RAF-MEK-ERK signaling
  • Trametinib
  • Tumor necrosis factor α (TNFα)

ASJC Scopus subject areas

  • Oncology
  • Clinical Neurology
  • Cancer Research


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