title: Multimodal cancer treatment mediated by a replicating oncolytic virus that delivers the oxazaphosphorine/rat cytochrome P450 2B1 and ganciclovir/herpes simplex virus thymidine kinase gene therapies.
abstract: Multimodal therapy is generally more effective than single-agent treatment for cancer. rRp450 is an engineered herpes simplex viral mutant that replicates in and kills tumor cells in a relatively selective fashion. It also expresses, in infected cells, the cyclophosphamide (CPA)-sensitive rat cytochrome P450 2B1 (CYP2B1) and the ganciclovir (GCV)-sensitive herpes simplex virus thymidine kinase (HSV-TK) transgenes. We show that cultured rat 9L and human U87deltaEGFR glioma cells, infected and lysed by rRp450, also exhibit supra-additive sensitivity to both CPA and GCV, as determined by Chou-Talalay synergy analysis. DNA cross-linking, assayed by ethidium bromide fluorescence, was significantly inhibited in the presence of GCV, suggesting that interactions between the CPA/CYP2B1 and GCV/HSV-TK gene therapies occurred at the level of DNA repair. In vivo, regression of 9L s.c. tumor volumes in athymic mice was achieved only by the multimodal treatment allowed by rRp450 viral oncolysis combined with CPA/CYP2B1 and GCV/HSV-TK gene therapies, whereas all other treatment combinations produced only tumor growth retardation.
authors.affiliation: Molecular Neuro-Oncology Laboratories, Neurosurgical Service, Massachusetts General Hospital, Boston 02114, USA.
authors.forename: M
authors.initials: M
authors.lastname: Aghi
authors.forename: T C
authors.initials: TC
authors.lastname: Chou
authors.forename: K
authors.initials: K
authors.lastname: Suling
authors.forename: X O
authors.initials: XO
authors.lastname: Breakefield
authors.forename: E A
authors.initials: EA
authors.lastname: Chiocca
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D003520:Cyclophosphamide / Q000031:analogs & derivatives / Q000627:therapeutic use*; D019362:Cytochrome P-450 CYP2B1 / Q000235:genetics; D015774:Ganciclovir / Q000627:therapeutic use*; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D005910:Glioma / Q000235:genetics* / Q000628:therapy*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D051381:Rats; D013937:Thymidine Kinase / Q000235:genetics; D014407:Tumor Cells, Cultured; D014779:Virus Replication; D014780:Viruses / Q000235:genetics*
chemical_list: D000970:Antineoplastic Agents; D003520:Cyclophosphamide; D019362:Cytochrome P-450 CYP2B1; D013937:Thymidine Kinase; D015774:Ganciclovir