The canine spontaneous glioblastoma as preclinical large animal model for brain cancer gene therapy

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

San Diego, California, USA

Congreso; American Association for Cancer Research; 2007

Abstract #4135The canine spontaneous glioblastoma as preclinical large animal model for brain cancer gene therapyMarianela Candolfi, James Curtin, W Nichols, Akm Muhammad, Mariana Puntel, Gwendalyn King, Weidong Xiong, Kurt Kroeger, Carlos Barcia, Chunyan Liu, Sonali Mondkar, G Pluhart, Elizabeth Mc Niel, John Ohlfest, Andrew Freese, Peter Moore, Donna Palmer, Philip Ng, John Young, Pedro Lowenstein and Maria CastroCedars Sinai Medical Center, Los Angeles, CA, University of Minnesota, St. Paul, MN, University of California Davis, Davis, CA, Baylor College of Medicine, Houston, TXIn search of large animal models in which to test novel therapeutics for glioblastoma (GBM) we performed a detailed histopathological characterization of dog spontaneous GBM and compared its features with those of human GBM. Also, considering that adenoviral (Ad) delivery of the immune-stimulatory molecule, Flt3L, and the conditional cytotoxic enzyme TK provides long-term survival in rodent GBM models, we tested Ad-mediated expression of therapeutic transgenes in the dog brain in vivo and in canine J3T GBM cells in vitro. Paraffin sections from human and spontaneous dog GBM were stained with H-E or processed for immunocytochemistry. Dog GBMs exhibited characteristic features of the human disease, including necrosis, pseudopalizading, neovascularization, endothelial proliferation and invasion into non-neoplastic brain. These tumors were also characterized by cellular pleomorphism, vimentin and GFAP immunoreactivity, as well as intense infiltration of macrophages and CD3+ lymphocytes. To establish the feasibility of using dogs bearing spontaneous GBM as a large model for preclinical research, we administered Ads encoding β-Gal, Flt3L or TK into the cerebral cortex of healthy Beagle dogs and assessed transgene expression by immunocytochemistry. Transgene expression of Flt3L and TK was detected in the dog brain without adverse clinical or neuropathological side effects. Further, we found that Ad-mediated transgene expression was higher when driven by the mCMV than the hCMV promoter in the dog brain without enhanced inflammation. Then we assessed in vitro the transduction efficiency of novel therapeutic regulated high capacity adenovirus vectors (HC-Ads) encoding β-Gal under control of the TetON system driven by the mCMV (HC-mTetON-β-Gal) or the hCMV promoter (HC-hTetON-β-Gal) and the therapeutic HC-Ad expressing HSV1-TK or Flt3L in J3T dog GBM cells. β-Gal activity in J3T cells was also higher with the HC-mTetON-β-Gal than with the HC-hTetON-β-Gal. J3T cells were efficiently transduced by HC-Ads expressing mCMV-driven HSV1-TK, which induced 90% cell death in the presence of gancyclovir. Expression of Flt3L under the control of the TetOn system was stringently inducer-dependent in these cells. Our data indicate that HC-Ads encoding therapeutic transgenes under the control of regulatory sequences driven by the mCMV promoter would constitute excellent vectors for the treatment of GBM in dogs, which emerges as an attractive animal model for testing novel therapeutic approaches in a spontaneous tumor in a larger brain.Support: NIH/NINDS 1R01 NS44556.01, Minority Supplement NS445561; NIH/NINDS 1 RO3 TW006273-01 to M.G.C.; NIH/NINDS 1 RO1 NS 42893.01; U54 NS045309-01, 1R21 NS047298-01, Bram and Elaine Goldsmith and Medallions Group Endowed Chairs in Gene Therapeutics to PRL and MGC, respectively, and Linda Tallen & David Paul Kane Annual Fellowship and the Board of Governors at CSMC.