Virus directed enzyme prodrug therapy for ovarian and pancreatic cancer using retrovirally delivered E. coli nitroreductase and CB1954

Gene Ther. 1998 Aug;5(8):1061-9. doi: 10.1038/


Expression of the E. coli enzyme nitroreductase (NTR) in tumour cells enables them to activate the prodrug CB1954 (5-(aziridin-1-yl)-2,4-dinitrobenzamide), leading to interstrand DNA crosslinking and cell death. Using transfected or retrovirally transduced SKOV3 ovarian carcinoma cell clones, we show a strong correlation between sensitivity to CB1954 and level of NTR enzyme activity. Importantly for clinical application in ovarian cancer, a cisplatin-resistant ovarian tumour cell line remains as susceptible to the NTR-dependent cytotoxicity of CB1954 as parental cells. In mixed populations of NTR-expressing and non-expressing cells, we observe a marked 'bystander killing' effect with this system. The use of NTR-encoding retroviruses from clonal producer cell lines at titres of 5 x 10(5) c.f.u./ml to transduce either established or low passage primary ovarian carcinoma lines only achieves an average 10-fold sensitisation of the cultures at gene transfer efficiencies of 15-25%. Concentration of the retrovirus to 3 x 10(7) c.f.u./ml elevates gene transfer to 80-90% in a single exposure to target cells, resulting in up to 500-fold sensitisation of the entire, unselected SKOV3 population to CB1954. In an initial investigation of NTR/CB1954 for the treatment of tumours in vivo, we observe regression of tumours expressing NTR following administration of CB1954, resulting in significantly increased median survival.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents / therapeutic use
  • Aziridines / therapeutic use
  • Female
  • Gene Transfer Techniques*
  • Genetic Therapy / methods*
  • Genetic Vectors
  • Mice
  • Mice, Inbred BALB C
  • Nitroreductases / genetics*
  • Ovarian Neoplasms / therapy*
  • Pancreatic Neoplasms / therapy*
  • Prodrugs / therapeutic use
  • Retroviridae


  • Antineoplastic Agents
  • Aziridines
  • Prodrugs
  • tretazicar
  • Nitroreductases