Adenovirus-mediated suicide gene therapy for experimental bladder cancer.
OBJECTIVE
To determine the feasibility, safety, and efficacy of suicide gene therapy using adenoviral-mediated herpes simplex virus thymidine kinase gene (HSV-tk) and the prodrug ganciclovir (GCV) in a murine model of human transitional cell carcinoma.


METHODS
We used a replication-defective adenoviral construct containing the beta-galactosidase gene (ADV/Rous sarcoma virus [RSV]-beta-gal) as a control or ADV/RSV-tk as the therapeutic vector under the transcriptional control of the RSV long-terminal repeat promoter. Transduction efficiency was assessed in vitro by infection of MBT-2 cells with ADV/RSV-beta-gal at various multiplicities of infection (MOI) utilizing 5-bromo-4-chlor-3-indolyl-beta-D-galactoside (X-gal) staining. Sensitivity of MBT-2 cells to the therapeutic vector was determined after infection with ADV/RSV-tk with or without GCV. Subcutaneous tumors were established in syngeneic C3H/He female mice with 5 x 10(5) MBT-2 cells. Optimal dosing of ADV/RSV-tk was determined by direct percutaneous tumor injection with increasing viral doses and treatment with GCV. Treatment efficacy, long-term survival, and toxicity were determined in separate, similar, controlled experiments.


RESULTS
In vitro studies indicated greater than 95% transduction 96 hours after inoculation at an MOI of 3000 and a greater than 95% cell death rate with RSV-tk + GCV at an MOI of 61 or greater. In vivo experiments demonstrated an optimal viral dose of 3 x 10(8) plaque-forming units (pfu) and a greater than fourfold reduction in tumor growth for the animals treated with ADV/RSV-tk compared with control animals (P = 0.0013). Toxicity was limited to histologic evidence of hepatitis with ADV/RSV-tk doses greater than 3 x 10(8) pfu + GCV. Long-term survival of treatment animals was significantly increased over that of control animals (59%, P = 0.0001).


CONCLUSIONS
ADV/RSV-tk with GCV treatment results in efficient gene transfer in vitro and provides effective therapy in experimental murine bladder cancer by significantly inhibiting tumor growth and improving host survival.
Sutton
M A
MA
Scott Department of Urology, Baylor College of Medicine, Houston, TX 77030, USA.
Berkman
S A
SA
Chen
S H
SH
Block
A
A
Dang
T D
TD
Kattan
M W
MW
Wheeler
T M
TM
Rowley
D R
DR
Woo
S L
SL
Lerner
S P
SP
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D002295:Carcinoma, Transitional Cell / Q000628:therapy*; D005240:Feasibility Studies; D015774:Ganciclovir; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D051379:Mice; D008809:Mice, Inbred C3H; D018139:Simplexvirus / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics; D001749:Urinary Bladder Neoplasms / Q000628:therapy*
D013937:Thymidine Kinase; D015774:Ganciclovir