A novel bi-cistronic high-capacity gutless adenovirus vector driving constitutive expression of HSV1-TK and Tet-inducible expression of Flt3L for glioma therapeutics

PUNTEL; MUHAMMAD; CANDOLFI; SALEM; YAGIZ; FARROKHI; KROEGER; XIONG; CURTIN; LIU; BONDALE; LERNER; PECHNICK; PALMER; NG; LOWENSTEIN; CASTRO

JOURNAL OF VIROLOGY

AMER SOC MICROBIOLOGY

Año: 2010 p. 6007 - 6017

0022-538X

GBM is a deadly primary brain tumor. Conditional cytotoxic/immune-stimulatory gene3 therapy (Ad-TK and Ad-Flt3L) elicits tumor regression and immunological memory in4 rodent GBM models. Since the majority of patients enrolled in clinical trials would exhibit5 adenovirus immunity which could curtail transgene expression and therapeutic efficacy,6 we used high-capacity adenovirus vectors (HC-Ads) as gene delivery platform. Herein,7 we describe for the first time a novel bi-cistronic HC-Ad driving constitutive expression8 of HSV1-TK and inducible Tet-mediated expression of Flt3L within a single vector9 platform. We achieved anti-GBM therapeutic efficacy with no overt toxicities using this10 bi-cistronic HC-Ad even in the presence of systemic Ad immunity. The bi-cistronic HC11Ad-TK/TetOn-Flt3L was delivered into intracranial gliomas in rats. Survival, vector12 biodistribution, neuropathology, systemic toxicity and neurobehavioral deficits were13 assessed for up to one year post-treatment. Therapeutic efficacy was also assessed in14 animals pre-immunized against Ads. We demonstrate therapeutic efficacy, with vector15 genomes restricted to the brain injection site and an absence of overt toxicities.16 Importantly, anti-adenoviral immunity did not inhibit therapeutic efficacy. These data17 represent the first report of a bi-cistronic vector platform driving the expression of two18 therapeutic transgenes, i.e., constitutive HSV1-TK and inducible Flt3L. Further, our data19 demonstrate no promoter interference and optimum gene delivery and expression from20 within this single vector platform. Analysis of the efficacy, safety, and toxicity of this21 bicistronic HC-Ad vector in an animal model of GBM strongly support further pre-clinical22 testing and downstream process development of HC-Ad-TK/TetOn-Flt3L for a future23 Phase I clinical trial for GBM.