JCI - Vector design influences hepatic genotoxicity after adeno-associated virus gene therapy

JCI - Vector design influences hepatic genotoxicity after adeno-associated virus gene therapy

J Clin Invest. doi:10.1172/JCI79213. 
Copyright © 2015, The American Society for Clinical Investigation.

Research Article

Vector design influences hepatic genotoxicity after adeno-associated virus gene therapy

Randy J. Chandler1, Matthew C. LaFave2, Gaurav K. Varshney2,Niraj S. Trivedi3, Nuria Carrillo-Carrasco4, Julien S. Senac1, Weiwei Wu5,Victoria Hoffmann6, Abdel G. Elkahloun5, Shawn M. Burgess2 andCharles P. Venditti1

1Genetics and Molecular Biology Branch,

2Translational and Functional Genomics Branch, and

3Computational and Statistical Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, Maryland, USA.

4Therapeutics for Rare and Neglected Diseases, National Center for Advancing Translational Sciences, NIH, Bethesda, Maryland, USA.

5Cancer Genetics and Comparative Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, Maryland, USA.

6Diagnostic and Research Services Branch, Office of the Director, NIH, Bethesda, Maryland, USA.

Address correspondence to: Charles P. Venditti, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, 49 Convent Drive Room 4A18, Bethesda, Maryland 20892-4472, USA. Phone: 301.496.6213; E-mail: venditti@mail.nih.gov.

Published January 20, 2015
Submitted: October 1, 2014; Accepted: December 11, 2014.

The use of adeno-associated virus (AAV) as a gene therapy vector has been approved recently for clinical use and has demonstrated efficacy in a growing number of clinical trials. However, the safety of AAV as a vector has been challenged by a single study that documented hepatocellular carcinoma (HCC) after AAV gene delivery in mice. Most studies have not noted genotoxicity following AAV-mediated gene delivery; therefore, the possibility that there is an association between AAV and HCC is controversial. Here, we performed a comprehensive study of HCC in a large number of mice following therapeutic AAV gene delivery. Using a sensitive high-throughput integration site-capture technique and global expressional analysis, we found that AAV integration into the RNA imprinted and accumulated in nucleus (Rian) locus, and the resulting overexpression of proximal microRNAs and retrotransposon-like 1 (Rtl1) were associated with HCC. In addition, we demonstrated that the AAV vector dose, enhancer/promoter selection, and the timing of gene delivery are all critical factors for determining HCC incidence after AAV gene delivery. Together, our results define aspects of AAV-mediated gene therapy that influence genotoxicity and suggest that these features should be considered for design of both safer AAV vectors and gene therapy studies.

Introduction

Adeno-associated virus (AAV) is regarded as nonpathogenic (1) and, when configured for gene therapy applications, is devoid of an intrinsic capacity to replicate and integrate. AAVs have therefore emerged as promising vectors for gene delivery (2) and have been extensively studied in small- and large-animal models for preclinical efficacy and safety (3). In fact, there are multiple human AAV gene therapy trials around the world that have been completed, are accruing participants, or are in preparation (4), and recent studies using AAV to treat 3 genetic disorders have been regarded as successful (5–8). In 2012, the first AAV treatment was approved for clinical use to treat lipoprotein lipase deficiency, a rare genetic disorder (9).