Spontaneous Glioblastoma in Dogs: Preclinical Model for High Capacity Adenovirus Vectors- Mediated Experimental Gene Therapy

CANDOLFI; CURTIN; NICKOLS; MUHAMMAD; PUNTEL; KING; XIONG; KROEGER; LIU; PLUHAR; MCNIEL; OHLFEST; FREESE; MOORE; PALMER; NG; YOUNG; LOWENSTEIN; CASTRO

Seattle, Washington, USA

Congreso; American Society of Gene Therapy; 2007

Spontaneous Glioblastoma in Dogs: Preclinical Model for High Capacity Adenovirus Vectors- Mediated Experimental Gene TherapyMarianela Candolfi1, James F Curtin1, W Stephen Nichols2, AKM Ghulam Muhammad1, Mariana Puntel1, Gwendalyn D King1, Weidong Xiong1, Kurt Kroeger1, Chunyan Liu1, G Elizabeth Pluhar3, Elizabeth A McNiel3, John R Ohlfest4, Andrew B Freese4, Peter F Moore5, Donna Palmer6, Phillip Ng6, John D. Young7, Pedro R. Lowenstein1, Maria G. Castro11 Gene Therapeutics Research Institute, Cedars-Sinai Medical Center, Dept of Medicine and Dept of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, 8700 Beverly Blvd., Davis Bldg., Rm: 5090, Los Angeles, CA 90048.2 Dept of Pathology and Laboratory Medicine, Cedars Sinai Medical Center, Los Angeles, CA 90048.3 Department of Veterinary Clinical Sciences, University of Minnesota, St. Paul, MN 551084 Department of Neurosurgery, University of Minnesota, Minneapolis, MN 55455.5 Pathology, Microbiology & Immunology, School of Veterinary Medicine, University of California Davis, CA 95616, USA6 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.7 Department of Comparative Medicine, Cedars Sinai Medical Center, Los Angeles, California 90034.Corresponding author: castromg@cshs.orgIn the present work we evaluated the dog spontaneous GBM as a large animal model for translational gene therapy strategies. We determined the neuropathological features of these tumors and the extent to which they resemble human GBM. We also determined the feasibility of infecting normal brain tissue in non-tumor bearing dogs by injecting adenoviral vectors expressing resporter and therapeutic trasngenes in the neocortex of healthy Beagle dogs. Considering that human patients usually exhibit preexisting immunity against adenoviruses (Ads), we determined whether outbreed dogs also exhibit preexisting immunity against adenoviral vectors. We found that dog GBMs exhibit characteristic features of the human disease, including necrosis, pseudopalizading, neovascularization, endothelial proliferation and invasion into non-neoplastic brain. In the brain of healthy Beagle dogs we administered Ad expressing the reporter gene -Galactosidase, or the therapeutic transgenes: TK, which kills glioma cells in the presence of ganciclovir (GCV), and the immunostimulatory Flt3L, which attracts antigen presenting cells to the brain and the tumor mass. Transgene expression was detected inneurons and astrocytes 7 days after the injection without adverse clinical or neuropathological side effects. We assessed the presence of neutralizing antibodies in serum from 17 outbred dogs recruited for our study. We found that 60% exhibited neutralizing antibodies against Ads. These data suggest that GBM-bearing dogs would also mimic the immune status of human patients in clinical trials. Our results suggest that high capacity-Ads are excellent candidates for treating dog GBM, since their expression is not inhibited by anti-Ad immune responses. Thus, we assessed the ability of HC-Ad vectors expressing HSV1-TK and Flt3L to infect and exert anti-tumoral effects in dog GBM cells in culture. HC-Ads were effective at transducing dog GBM cells. HC-Ad-HSV1-TK elicited strong cytotoxic effects when combined with GCV. Our data indicate that dogs bearing spontaneous GBM constitute an attractive animal model for testing novel therapeutic approaches in a spontaneous tumor in the context of a larger brain.Supported by: National Institutes of Health/National Institute of Neurological Disorders & Stroke (NIH/NINDS) Grants 1R01 NS44556.01, Minority Supplement NS445561; 1 R21 NS054143-01 and 1 RO3 TW006273-01 to M.G.C.; NIH/NINDS Grants 1 RO1 NS 42893.01; U54 NS045309-01, and 1R21 NS047298-01 to PRL; the Bram and Elaine Goldsmith and the Medallions Group Endowed Chairs in Gene Therapeutics to PRL and MGC, respectively, and The Linda Tallen & David Paul Kane Foundation and the Board of Governors at CSMC.