Translating SOD1 Gene Silencing toward the Clinic: A Highly Efficacious, Off-Target-free, and Biomarker-Supported Strategy for fALS

Tommaso Iannitti; Joseph M Scarrott; Shibi Likhite; Ian R P Coldicott; Katherine E Lewis; Paul R Heath; Adrian Higginbottom; Monika A Myszczynska; Marta Milo; Guillaume M Hautbergue; Kathrin Meyer; Brian K Kaspar; Laura Ferraiuolo; Pamela J Shaw; Mimoun Azzouz

doi:10.1016/j.omtn.2018.04.015

Translating SOD1 Gene Silencing toward the Clinic: A Highly Efficacious, Off-Target-free, and Biomarker-Supported Strategy for fALS

Mol Ther Nucleic Acids. 2018 Sep 7:12:75-88. doi: 10.1016/j.omtn.2018.04.015. Epub 2018 May 3.

Authors

Affiliations

¹ University of Sheffield, Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, Sheffield, UK.
² Center for Gene Therapy, Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, College of Medicine and Public Health, The Ohio State University, Columbus, OH, USA.
³ Center for Gene Therapy, Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, College of Medicine and Public Health, The Ohio State University, Columbus, OH, USA; Department of Neuroscience, The Ohio State University, Columbus, OH, USA.
⁴ University of Sheffield, Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, Sheffield, UK. Electronic address: pamela.shaw@sheffield.ac.uk.
⁵ University of Sheffield, Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, Sheffield, UK. Electronic address: m.azzouz@sheffield.ac.uk.

Abstract

Of familial amyotrophic lateral sclerosis (fALS) cases, 20% are caused by mutations in the gene encoding human cytosolic Cu/Zn superoxide dismutase (hSOD1). Efficient translation of the therapeutic potential of RNAi for the treatment of SOD1-ALS patients requires the development of vectors that are free of significant off-target effects and with reliable biomarkers to discern sufficient target engagement and correct dosing. Using adeno-associated virus serotype 9 to deliver RNAi against hSOD1 in the SOD1^G93A mouse model, we found that intrathecal injection of the therapeutic vector via the cisterna magna delayed onset of disease, decreased motor neuron death at end stage by up to 88%, and prolonged the median survival of SOD1^G93A mice by up to 42%. To our knowledge, this is the first report to demonstrate no significant off-target effects linked to hSOD1 silencing, providing further confidence in the specificity of this approach. We also report the measurement of cerebrospinal fluid (CSF) hSOD1 protein levels as a biomarker of effective dosing and efficacy of hSOD1 knockdown. Together, these data provide further confidence in the safety of the clinical therapeutic vector. The CSF biomarker will be a useful measure of biological activity for translation into human clinical trials.

Keywords: AAV9; ALS; SOD1; biomarker; cisterna magna; clinical vector; motor neuron; neurodegeneration; off-target effects; shRNA.

Abstract

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