Cytokine conditioning enhances systemic delivery and therapy of an oncolytic virus

Elizabeth Ilett, Timothy Kottke, Oliver Donnelly, Jill Thompson, Candice Willmon, Rosa Diaz, Shane Zaidi, Matt Coffey, Peter Selby, Kevin Harrington, Hardev Pandha, Alan Melcher, Richard Vile

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


Optimum clinical protocols require systemic delivery of oncolytic viruses in the presence of an intact immune system. We show that preconditioning with immune modulators, or loading virus onto carrier cells ex vivo, enhances virus-mediated antitumor activity. Our early trials of systemic reovirus delivery showed that after infusion reovirus could be recovered from blood cells - but not from plasma - suggesting that rapid association with blood cells may protect virus from neutralizing antibody. We therefore postulated that stimulation of potential carrier cells directly in vivo before intravenous viral delivery would enhance delivery of cell-associated virus to tumor. We show that mobilization of the CD11b + cell compartment by granulocyte macrophage-colony stimulating factor immediately before intravenous reovirus, eliminated detectable tumor in mice with small B16 melanomas, and achieved highly significant therapy in mice bearing well-established tumors. Unexpectedly, cytokine conditioning therapy was most effective in the presence of preexisting neutralizing antibody. Consistent with this, reovirus bound by neutralizing antibody effectively accessed monocytes/macrophages and was handed off to tumor cells. Thus, preconditioning with cytokine stimulated recipient cells in vivo for enhanced viral delivery to tumors. Moreover, preexisting neutralizing antibody to an oncolytic virus may, therefore, even be exploited for systemic delivery to tumors in the clinic.

Original languageEnglish (US)
Pages (from-to)1851-1863
Number of pages13
JournalMolecular Therapy
Issue number10
StatePublished - Jan 1 2014

ASJC Scopus subject areas

  • Molecular Medicine
  • Molecular Biology
  • Genetics
  • Pharmacology
  • Drug Discovery


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