Title

Direct Intracranial Injection of AAVrh8 Encoding Monkey beta-N-Acetylhexosaminidase Causes Neurotoxicity in the Primate Brain

UMMS Affiliation

Department of Neurology; Horae Gene Therapy Center; Department of Radiology; New England Center for Stroke Research; Department of Animal Medicine

Date

6-1-2017

Document Type

Article

Disciplines

Genetics and Genomics | Radiology | Therapeutics

Abstract

GM2 gangliosidoses, including Tay-Sachs disease and Sandhoff disease, are lysosomal storage disorders caused by deficiencies in beta-N-acetylhexosaminidase (Hex). Patients are afflicted primarily with progressive central nervous system (CNS) dysfunction. Studies in mice, cats, and sheep have indicated safety and widespread distribution of Hex in the CNS after intracranial vector infusion of AAVrh8 vectors encoding species-specific Hex alpha- or beta-subunits at a 1:1 ratio. Here, a safety study was conducted in cynomolgus macaques (cm), modeling previous animal studies, with bilateral infusion in the thalamus as well as in left lateral ventricle of AAVrh8 vectors encoding cm Hex alpha- and beta-subunits. Three doses (3.2 x 1012 vg [n = 3]; 3.2 x 1011 vg [n = 2]; or 1.1 x 1011 vg [n = 2]) were tested, with controls infused with vehicle (n = 1) or transgene empty AAVrh8 vector at the highest dose (n = 2). Most monkeys receiving AAVrh8-cmHexalpha/beta developed dyskinesias, ataxia, and loss of dexterity, with higher dose animals eventually becoming apathetic. Time to onset of symptoms was dose dependent, with the highest-dose cohort producing symptoms within a month of infusion. One monkey in the lowest-dose cohort was behaviorally asymptomatic but had magnetic resonance imaging abnormalities in the thalami. Histopathology was similar in all monkeys injected with AAVrh8-cmHexalpha/beta, showing severe white and gray matter necrosis along the injection track, reactive vasculature, and the presence of neurons with granular eosinophilic material. Lesions were minimal to absent in both control cohorts. Despite cellular loss, a dramatic increase in Hex activity was measured in the thalamus, and none of the animals presented with antibody titers against Hex. The high overexpression of Hex protein is likely to blame for this negative outcome, and this study demonstrates the variations in safety profiles of AAVrh8-Hexalpha/beta intracranial injection among different species, despite encoding for self-proteins.

Rights and Permissions

Citation: Hum Gene Ther. 2017 Jun;28(6):510-522. doi: 10.1089/hum.2016.109. Epub 2017 Jan 26. Link to article on publisher's site

Related Resources

Link to Article in PubMed

Keywords

AAV, Tay-Sachs disease, adeno-associated virus, gene therapy, hexosaminidase, intracranial delivery

PubMed ID

28132521