title: Targeted chemotherapy for head and neck cancer with a chimeric oncolytic adenovirus coding for bifunctional suicide protein FCU1.
abstract: OBJECTIVE
  Transfer of prodrug activation systems into tumors by using replication-deficient viruses has been suggested to be an effective method for achieving high local and low systemic anticancer drug concentrations. However, most current suicide gene therapy strategies are still hindered by poor efficiency of in vivo gene transfer, inefficient tumor penetration, limited bystander cell killing effect, and need of large prodrug doses. We hypothesized that local amplification provided by a replication competent platform would help overcome these limitations.
  
  
  METHODS
  We generated a transductionally and transcriptionally targeted oncolytic adenovirus Ad5/3-Delta24FCU1 expressing the fusion suicide gene FCU1. FCU1 encodes a bifunctional fusion protein that efficiently catalyzes the direct conversion of 5-FC, a relatively nontoxic antifungal agent, into the toxic metabolites 5-fluorouracil and 5-fluorouridine monophosphate, bypassing the natural resistance of certain human tumor cells to 5-fluorouracil.
  
  
  RESULTS
  We examined the efficacy of Ad5/3-Delta24FCU1 and the replication-defective control Ad5/3-FCU1 with and without 5-FC. FCU1 expression was confirmed by Western blot, whereas enzymatic conversion levels in vitro and in vivo were determined by high-performance liquid chromatography separation. Significant antitumor effect was observed in vitro and in vivo in a murine model of head and neck squamous cell carcinoma. Although we observed a decrease in viral DNA copy number in vitro and in tumors treated with Ad5/3-Delta24FCU1 and 5-FC, suggesting an effect on virus replication, the highest antitumor effect was observed for this combination.
  
  
  CONCLUSIONS
  It seems feasible and efficacious to combine adenovirus replication to the FCU1 prodrug activation system.
authors.affiliation: Cancer Gene Therapy Group, Molecular Cancer Biology Program & Transplantation Laboratory & Haartman Institute & Finnish Institute for Molecular Medicine, Helsinki, Finland.
authors.forename: João D
authors.initials: JD
authors.lastname: Dias
authors.forename: Ilkka
authors.initials: I
authors.lastname: Liikanen
authors.forename: Kilian
authors.initials: K
authors.lastname: Guse
authors.forename: Johann
authors.initials: J
authors.lastname: Foloppe
authors.forename: Marta
authors.initials: M
authors.lastname: Sloniecka
authors.forename: Iulia
authors.initials: I
authors.lastname: Diaconu
authors.forename: Ville
authors.initials: V
authors.lastname: Rantanen
authors.forename: Minna
authors.initials: M
authors.lastname: Eriksson
authors.forename: Tanja
authors.initials: T
authors.lastname: Hakkarainen
authors.forename: Monika
authors.initials: M
authors.lastname: Lusky
authors.forename: Philippe
authors.initials: P
authors.lastname: Erbs
authors.forename: Sophie
authors.initials: S
authors.lastname: Escutenaire
authors.forename: Anna
authors.initials: A
authors.lastname: Kanerva
authors.forename: Sari
authors.initials: S
authors.lastname: Pesonen
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Cerullo
authors.forename: Akseli
authors.initials: A
authors.lastname: Hemminki
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D043525:Cytosine Deaminase / Q000235:genetics / Q000378:metabolism; D005260:Female; D005437:Flucytosine / Q000378:metabolism / Q000494:pharmacology; D005472:Fluorouracil / Q000378:metabolism / Q000494:pharmacology; D041722:Genes, Transgenic, Suicide / Q000235:genetics; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics; D006258:Head and Neck Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D006801:Humans; D051379:Mice; D008815:Mice, Inbred Strains; D008819:Mice, Nude; D050504:Oncolytic Viruses / Q000235:genetics; D010430:Pentosyltransferases / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D014161:Transduction, Genetic; D023041:Xenograft Model Antitumor Assays
chemical_list: D011993:Recombinant Fusion Proteins; D005437:Flucytosine; D010430:Pentosyltransferases; C023269:uracil phosphoribosyltransferase; D043525:Cytosine Deaminase; D005472:Fluorouracil