Systemic cancer therapy with a tumor-selective vaccinia virus mutant lacking thymidine kinase and vaccinia growth factor genes

J. Andrea McCart, Jerrold M. Ward, John Lee, Yun Hu, H. Richard Alexander, Steven K. Libutti, David L. Bartlett, Bernard Moss, Jerrold M. Ward

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309 Scopus citations


We have demonstrated previously the oncolytic effects of a systemically delivered, replicating vaccinia virus. To enhance the tumor specificity of this vector, we have developed a combined thymidine kinase-deleted (TK-) and vaccinia growth factor-deleted (VGF-) vaccinia virus and investigated its properties in vitro and in vivo. The gene for enhanced green fluorescent protein (EGFP) was inserted into the TK locus of a VGF- vaccinia virus by homologous recombination creating a double-deleted mutant vaccinia virus (vvDD-GFP). Infection of resting and dividing NIH3T3 cells with vvDD-GFP yielded reduced viral recovery compared with wild-type (WT), TK-, or VGF- viruses from resting cultures but equivalent virus recovery from dividing cultures. Eight days after nude mice were injected i.p. with 107 plaque-forming units (pfu) of WT, TK-, VGF-, or vvDD-GFP vaccinia virus, tissues and tumor were harvested for viral titer determination. No virus was recovered from the brains of mice injected with vvDD-GFP compared with the other viruses, which ranged from 130 to 28, 000 pfu/mg protein; however, equivalent amounts were recovered from tumor. There was no toxicity from vvDD-GFP because nude mice receiving 108 pfu of IP vvDD-GFP lived >100 days, whereas mice receiving WT, VGF-, or TK- virus had median survivals of only 6, 17, and 29 days, respectively. Similar results were seen when 109 pfu of vvDD-GFP were given. Nude mice bearing s.c. murine colon adenocarcinoma (MC38) had significant tumor regression after treatment with 109 pfu of systemic (i.p.) vvDD-GFP compared with control (mean tumor size, 180.71 ± 35.26 mm3 versus 2796.79 ± 573.20 mm3 12 days after injection of virus). Our data demonstrate that a TK- and VGF- mutant vaccinia virus is significantly attenuated in resting cells in vitro and demonstrates tumor-specific replication in vivo. It is a promising vector for use in tumor-directed gene therapy, given its enhanced safety profile, tumor selectivity, and the oncolytic effects after systemic delivery.

Original languageEnglish (US)
Pages (from-to)8751-8757
Number of pages7
JournalCancer Research
Issue number24
StatePublished - Dec 15 2001
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research


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