Long-term treatment with valganciclovir improves lentiviral suicide gene therapy of glioblastoma

Jubayer A. Hossain, Md A. Latif, Lars A.R. Ystaas, Sandra Ninzima, Kristoffer Riecken, Arnaud Muller, Francisco Azuaje, Justin V. Joseph, Krishna M. Talasila, Jiwan Ghimire, Boris Fehse, Rolf Bjerkvig, Hrvoje Miletic*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

23 Citations (Scopus)


Background: Suicide gene therapy for malignant gliomas has shown encouraging results in the latest clinical trials. However, prodrug application was most often restricted to short-term treatment (14 days), especially when replication-defective vectors were used. We previously showed that a substantial fraction of herpes simplex virus thymidine kinase (HSV-TK) transduced tumor cells survive ganciclovir (GCV) treatment in an orthotopic glioblastoma (GBM) xenograft model. Here we analyzed whether these TK+ tumor cells are still sensitive to prodrug treatment and whether prolonged prodrug treatment can enhance treatment efficacy. Methods: Glioma cells positive for TK and green fluorescent protein (GFP) were sorted from xenograft tumors recurring after suicide gene therapy, and their sensitivity to GCV was tested in vitro. GBM xenografts were treated with HSV-TK/GCV, HSV-TK/valganciclovir (valGCV), or HSV-TK/valGCV + erlotinib. Tumor growth was analyzed by MRI, and survival as well as morphological and molecular changes were assessed. Results: TK-GFP+ tumor cells from recurrent xenograft tumors retained sensitivity to GCV in vitro. Importantly, a prolonged period (3 mo) of prodrug administration with valganciclovir (valGCV) resulted in a significant survival advantage compared with short-term (3 wk) application of GCV. Recurrent tumors from the treatment groups were more invasive and less angiogenic compared with primary tumors and showed significant upregulation of epidermal growth factor receptor (EGFR) expression. However, double treatment with the EGFR inhibitor erlotinib did not increase therapeutic efficacy. Conclusion: Long-term treatment with valGCV should be considered as a replacement for short-term treatment with GCV in clinical trials of HSV-TK mediated suicide gene therapy.

Original languageEnglish
Article numbernoz060
Pages (from-to)890-900
Number of pages11
Issue number7
Publication statusPublished - 11 Jul 2019


  • EGFR
  • brain tumors
  • glioblastoma
  • lentiviral vectors
  • suicide gene therapy


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