Global CNS gene delivery and evasion of anti-AAV-neutralizing antibodies by intrathecal AAV administration in non-human primates

Abstract

Injection of AAV into the cerebrospinal fluid (CSF) offers a means to achieve widespread transgene delivery to the central nervous system, where the doses can be readily translated from small to large animals. In contrast to studies with other serotypes (AAV2, AAV4, AAV5) in rodents, we report that a naturally-occurring capsid (AAV9) and rationally-engineered capsid (AAV2.5) are able to achieve broad transduction throughout the brain and spinal cord parenchyma following a single injection into the CSF (via cisterna magna or lumbar cistern) in non-human primates (NHP). Using either vector at a dose of ~2×1012 vg per 3-6 kg animal, approximately 2% of the entire brain and spinal cord was transduced, covering all regions of the CNS. AAV9 in particular displayed efficient transduction of spinal cord motor neurons. The peripheral organ biodistribution was highly reduced compared to intravascular delivery, and the presence of circulating anti-AAV neutralizing antibodies up to a 1:128 titer had no inhibitory effect on CNS gene transfer. Intra-CSF delivery effectively translates from rodents to NHPs, which provides encouragement for the use of this approach in humans to treat motor neuron and lysosomal storage diseases.

Gene Therapy for the Nervous System: Challenges and New Strategies

“…For instance, vector administered via the bloodstream is most vulnerable to elimination by antibody neutralization and opsonization [32][33][34]. Direct injection into the brain parenchyma [35] or CSF [36] can achieve transduction in the presence of antibodies in at least some cases as the antibody concentration is much lower in these sites than in the blood. The intensity of the innate and adaptive immune response is vector type related.…”

“…The field of CNS gene therapy is evolving rapidly with the discovery of new viral vectors, mainly AAV capsids, with remarkable CNS tropism after vascular [21,36,49,[96][97][98], and CSF administration [18,36,47]. A large range of AAV capsids has been investigated for their CNS gene transfer properties by direct intracranial injection [99][100][101][102].…”

Making the White Matter Matters: Progress in Understanding Canavan’s Disease and Therapeutic Interventions Through Eight Decades

“…Discovery of more serotypes that can cross the BBB (Zhang et al 2011;Yang et al 2014) paves the way for more efficient CNS gene transfer using the rAAV vectors. It is noteworthy that the rAAV vectors appear to be relatively consistent in their CNS gene transfer properties even across animal models like cats, dogs, and monkeys (Duque et al 2009;Gray et al 2013;Swain et al 2013). …”

Recent Advances in RNA Interference Therapeutics for CNS Diseases

“…Widespread exposure of a transgene product occurs after intraventricular or intrathecal delivery of AAVs, when the transgene product is a secreted molecule [75]. Recently, intrathecal injection of AAV9 or AAV2.5 showed robust transduction of the brain and spinal cord in nonhuman primates [76].…”