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

MARIANA PUNTEL; AKM GHULAM MUHAMMAD; MARIANELA CANDOLFI; ALIREZA SALEM; KADER YAGIZ; CATHERINE FARROKI; KURT M KROEGER; WEIDONG XIONG; JAMES F CURTIN; CHUNYAN LIU; NIYATI S BONDALE; JONATHAN LERNER; ROBERT N PECHNICK; DONNA PALMER; PHILLIP NG; PEDRO R LOWENSTEIN; MARIA G CASTRO

JOURNAL OF VIROLOGY

AMER SOC MICROBIOLOGY

Año: 2010 vol. 84 p. 6007 - 6017

0022-538X

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