Reprogramming Immune Response With Capsid-Optimized AAV6 Vectors for Immunotherapy of Cancer.
In the current studies we generated novel capsid-optimized adeno-associated virus (AAV) serotype 6 (AAV6) vectors expressing a tumor-associated antigen, and assessed their ability to activate a protective T-cell response in an animal model. First, we showed that specific mutations in the AAV6 capsid increase the transduction efficiency of these vectors in mouse bone marrow-derived dendritic cells in vitro for approximately 5-fold compared with the wild-type (WT) AAV6 vectors. Next, we evaluated the ability of the mutant AAV6 vectors to initiate specific T-cell clone proliferation in vivo. Our data indicate that the intramuscular administration of AAV6-S663V+T492V vectors expressing ovalbumin (OVA) led to a strong activation (approximately 9%) of specific T cells in peripheral blood compared with AAV6-WT treated animals (<1%). These OVA-specific T cells have a superior killing ability against mouse prostate cancer cell line RM1 stably expressing the OVA antigen when propagated in vitro. Finally, we evaluated the ability of capsid-optimized AAV6-S663V+T492V vectors to initiate a protective anticancer immune response in vivo. Our results document the suppression of subcutaneous tumor growth in animals immunized with AAV6-S663V+T492V vectors expressing prostatic acid phosphatase (PAP) for approximately 4 weeks in comparison with 1 week and 2 weeks for the negative controls, AAV6-EGFP, and AAV6-WT-PAP treated mice, respectively. These studies suggest that successful inhibition of tumor growth in an animal model would set the stage for potential clinical application of the capsid-optimized AAV6-S663V+T492V vectors.
*Department of Microbiology and Cell Science †Department of Pediatrics, Division of Cellular and Molecular Therapy ‡Powell Gene Therapy Center §Shands Cancer Center, University of Florida College of Medicine, Gainesville, FL.
Munjal
M
Pandya
Kellee
K
Britt
Brad
B
Hoffman
Chen
C
Ling
George V
GV
Aslanidi
D000818:Animals; D002213:Capsid / Q000276:immunology*; D036022:Capsid Proteins / Q000276:immunology*; D045744:Cell Line, Tumor; D000229:Dependovirus / Q000276:immunology*; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors / Q000276:immunology*; D007167:Immunotherapy / Q000379:methods; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009369:Neoplasms / Q000276:immunology*; D010047:Ovalbumin / Q000276:immunology; D011471:Prostatic Neoplasms / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D014161:Transduction, Genetic / Q000379:methods
D036022:Capsid Proteins; D010047:Ovalbumin