Efficient, long-term hepatic gene transfer using clinically relevant HDAd doses by balloon occlusion catheter delivery in nonhuman primates

Abstract

Helper-dependent adenoviral vectors (HDAd) are devoid of all viral coding sequences and are thus an improvement over early generation Ad because they can provide long-term transgene expression in vivo without chronic toxicity. However, high vector doses are required to achieve efficient hepatic transduction by systemic intravenous injection, and this unfortunately results in dose-dependent acute toxicity. To overcome this important obstacle, we have developed a minimally invasive method to preferentially deliver HDAd into the liver of nonhuman primates. Briefly, a balloon occlusion catheter was percutaneously positioned in the inferior vena cava to occlude hepatic venous outflow. HDAd was injected directly into the occluded liver via a percutaneously placed hepatic artery catheter. Compared to systemic vector injection, this approach resulted in substantially higher hepatic transduction efficiency using clinically relevant low vector doses and was accompanied by mild-to-moderate acute but transient toxicities. Transgene expression was sustained for up to 964 days. These results suggest that our minimally invasive method of delivery can significantly improve the vector's therapeutic index and may be a first step toward clinical application of HDAd for liver-directed gene therapy.

Figure 1

A sausage-shaped balloon catheter is positioned in the inferior vena cava (IVC) under fluoroscopic guidance. Inflation of the balloon with contrast medium results in hepatic venous outflow occlusion from the hepatic veins (HVs). The HDAd is administered by injection through a percutaneously positioned hepatic artery (HA) catheter. Fluoroscopic image of balloon inflation with contrast medium from baboon 16855 is shown on the left. Fluoroscopic image of injection of contrast medium into the HA from baboon 11891 is shown on the right.

Figure 2

Transgene levels and toxicity measurements for baboons injected with 1 × 10¹¹ viral particles (vp)/kg. (a) Serum baboon α-fetoprotein (bAFP) levels, (b) alanine aminotransferase (ALT), (c) aspartate aminotransferase (AST), and (d) interleukin-6 (IL-6) levels in baboons injected 1 × 10¹¹ vp/kg of HDΔ21.7E4PEPCK-bAFP-WL or saline. Numbers in parenthesis represent the normal range, if known.

Figure 3

Transgene levels and toxicity measurements for baboons injected with 3 × 10¹⁰ and 1 × 10¹⁰ viral particles (vp)/kg. (a) Serum baboon α-fetoprotein (bAFP) levels, (b) alanine aminotransferase (ALT), (c) aspartate aminotransferase (AST), and (d) interleukin-6 (IL-6) levels in baboons injected 3 × 10¹⁰ or 1 × 10¹⁰ vp/kg of HDΔ21.7E4PEPCK-bAFP-WL. Numbers in parenthesis represent the normal range, if known.

Figure 4

Histopathology of baboon livers. Hematoxylin and eosin histology of liver from baboon 16290 at (a) day 8 and (b) day 28, baboon 16728 at (c) day 7 and (d) day 28, (e) baboon 16105 at day 28 and (f) baboon 16966 at day 28 showing rare and minor abnormalities.