Helper-dependent adenoviral vectors mediate therapeutic factor VIII expression for several months with minimal accompanying toxicity in a canine model of severe hemophilia A

• Published in: Blood 2004-02, Vol.103 (3), p.804-810
• Main Authors: Brown, Brian D., Shi, Chang Xin, Powell, Sandra, Hurlbut, David, Graham, Frank L., Lillicrap, David
• Format: Article
• Language: English
• Subjects: Acute-Phase Reaction - etiology; Adenoviridae - genetics; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Applied cell therapy and gene therapy; Base Sequence; Biological and medical sciences; Disease Models, Animal; DNA, Recombinant - genetics; DNA, Recombinant - metabolism; Dogs; Factor VIII - genetics; Factor VIII - metabolism; Gene Expression; Genetic Therapy - adverse effects; Genetic Therapy - methods; Genetic Vectors; Helper Viruses - genetics; Hematologic and hematopoietic diseases; Hemophilia A - blood; Hemophilia A - genetics; Hemophilia A - therapy; Liver - injuries; Liver - metabolism; Medical sciences; Phenotype; Platelet diseases and coagulopathies; Promoter Regions, Genetic; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; RNA - genetics; RNA - metabolism; Thrombocytopenia - etiology; Transfusions. Complications. Transfusion reactions. Cell and gene therapy
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2003-05-1426

Two helper-dependent (HD) adenoviral vectors encoding a canine factor VIII B-domain–deleted transgene (cFVIII) were constructed and evaluated in 4 hemophilia A dogs. One vector was regulated by the cytomegalovirus (CMV) promoter (HD-CMV-cFVIII), while the other vector contained a tissue-restricted promoter comprised of the human FVIII proximal promoter with an upstream concatemer of 5 hepatocyte nuclear factor 1 binding sites (HD-HNF-cFVIII). We detected no toxicity at low dose (5 × 1011 vp/kg), but at higher vector doses (> 1 × 1012 vp/kg) transient hepatotoxicity and thrombocytopenia were observed. Low-level increases in FVIII activity were detected in all 3 HD-HNF-cFVIII–treated dogs, which corresponded with decreased whole blood clotting times. None of the animals receiving the HD-HNF-cFVIII vector developed FVIII inhibitors, and in 1 of the 3 animals, FVIII activity was sustained for over 6 months after treatment. One animal, which received the HD-CMV-cFVIII vector, achieved peak levels of FVIII above 19 000 mU/mL, but FVIII activity disappeared within 1 week, coincident with the development of a potent anti–canine FVIII antibody response. This study supports previous demonstrations of improved safety using HD gene transfer and suggests that these vectors can provide transient FVIII expression with minimal, acute toxicity in the absence of inhibitor formation.