High doses of a helper-dependent adenoviral vector yield supraphysiological levels of alpha(1)-antitrypsin with negligible toxicity

Optimal gene therapy for many disorders will require efficient transfer to cells in vivo, high-level and longterm expression, and tissue-specific regu lation, all in the absence of significant toxicity or inflammatory response s, While recombinant adenoviral vectors are efficient for gene transfer to hepatocytes, their usefulness is limited by short duration of expression re lated, at least in part, to immune responses to viral proteins and by a low capacity for foreign DNA. A number of systems have been developed for prod ucing adenoviral vectors devoid of all viral coding sequences. Using AdSTK1 09, a vector lacking all viral coding sequences and carrying the complete h uman alpha(1)-antitrypsin (hAAT) genomic DNA locus, we have demonstrated su stained expression for longer than 10 months in mice. Utilizing high doses of this vector for hepatic gene transfer in mice, we find that supraphysiol ogical levels of hAAT can be achieved without hepatotoxicity.