A conditionally replicative adenovirus that codes for a TK-GFP fusion protein (Ad5Delta24TK-GFP) for evaluation of the potency of oncolytic virotherapy combined with molecular chemotherapy.
The utility of conditionally replicative adenoviruses (CRAds) in cancer gene therapy is based on their ability to destroy tumor cells by oncolysis. However, in order to achieve adequate therapeutic response, CRAds have to spread through the tumor tissue by replication. Thus, to study the potency of these viruses to replicate and penetrate in tumors, we created a herpes simplex virus type 1 thymidine kinase-green fluorescent protein fusion gene (TK-GFP) encompassing CRAd (Ad5Delta24TK-GFP), whose tumor selectivity is mediated by a retinoblastoma (Rb)-binding site mutation. In addition, we evaluated the oncolytic efficacy of Ad5Delta24TK-GFP in combination with the TK/ganciclovir (GCV) system. Based on our results, Ad5Delta24TK-GFP replicates in cancer cells resulting in oncolysis and can efficiently penetrate into tumors. Additionally, the combination of GCV with Ad5Delta24TK-GFP augmented cell death in vitro but this was not observed in vivo: tumor growth was significantly reduced by oncolysis when compared to non-replicative virus (p<0.001), but administration of GCV did not significantly enhance oncolysis. This suggests that in certain conditions, TK/GCV-mediated cell killing may be counterproductive to replication and oncolysis, which on the other hand might be useful feature for clinical trials in case of replication-associated toxicity.
Hakkarainen
Tanja
T
Rational Drug Design Program, University of Helsinki, 00014 University of Helsinki, Helsinki, Finland. tanja.m.hakkarainen@helsinki.fi
Hemminki
Akseli
A
Curiel
David T
DT
Wahlfors
Jarmo
J
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology / Q000627:therapeutic use; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003131:Combined Modality Therapy; D005260:Female; D015774:Ganciclovir / Q000494:pharmacology / Q000627:therapeutic use*; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics / Q000493:pharmacokinetics; D049452:Green Fluorescent Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D051379:Mice; D008815:Mice, Inbred Strains; D008819:Mice, Nude; D050130:Oncolytic Virotherapy / Q000379:methods*; D010051:Ovarian Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000378:metabolism / Q000493:pharmacokinetics; D013937:Thymidine Kinase / Q000235:genetics* / Q000378:metabolism; D014779:Virus Replication; D023041:Xenograft Model Antitumor Assays / Q000379:methods
D000998:Antiviral Agents; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D013937:Thymidine Kinase; D015774:Ganciclovir