Comparative Efficacy and Safety of Multiple Routes of Direct CNS Administration of Adeno-Associated Virus Gene Transfer Vector Serotype rh.10 Expressing the Human Arylsulfatase A cDNA to Nonhuman Primates

Abstract

Metachromatic leukodystrophy (MLD), a fatal disorder caused by deficiency of the lysosomal enzyme arylsulfatase A (ARSA), is associated with an accumulation of sulfatides, causing widespread demyelination in both central and peripheral nervous systems. On the basis of prior studies demonstrating that adeno-associated virus AAVrh.10 can mediate widespread distribution in the CNS of a secreted lysosomal transgene, and as a prelude to human trials, we comparatively assessed the optimal CNS delivery route of an AAVrh.10 vector encoding human ARSA in a large animal model for broadest distribution of ARSA enzyme. Five routes were tested (each total dose, 1.5 · 10 12 genome copies of AAVrh.10hARSA-FLAG): (1) delivery to white matter centrum ovale; (2) deep gray matter delivery (putamen, thalamus, and caudate) plus overlying white matter; (3) convection-enhanced delivery to same deep gray matter locations; (4) lateral cerebral ventricle; and (5) intraarterial delivery with hyperosmotic mannitol to the middle cerebral artery. After 13 weeks, the distribution of ARSA activity subsequent to each of the three direct intraparenchymal administration routes was significantly higher than in phosphate-buffered saline-administered controls, but administration by the intraventricular and intraarterial routes failed to demonstrate measurable levels above controls. Immunohistochemical staining in the cortex, white matter, deep gray matter of the striatum, thalamus, choroid plexus, and spinal cord dorsal root ganglions confirmed these results. Of the five routes studied, administration to the white matter generated the broadest distribution of ARSA, with 80% of the brain displaying more than a therapeutic (10%) increase in ARSA activity above PBS controls. No significant toxicity was observed with any delivery route as measured by safety parameters, although some inflammatory changes were seen by histopathology. We conclude that AAVrh.10-mediated delivery of ARSA via CNS administration into the white matter is likely to be safe and yields the widest distribution of ARSA, making it the most suitable route of vector delivery.

Pervasive supply of therapeutic lysosomal enzymes in the CNS of normal and Krabbe‐affected non‐human primates by intracerebral lentiviral gene therapy

“…The local neuroinflammation in the vicinity of the injection areas, which we found in some treated animals, was previously reported in AAV‐ (Colle et al , ; Salegio et al , ; Rosenberg et al , ) and LV‐injected NHP (Kordower et al , ; Jarraya et al , ), being mainly associated with tissue damage (consequent to the surgical procedure), persistence of injected soluble material, and/or immune response. Our data suggest that macrophage and mononuclear cell infiltrates observed to a different extent in LV.GFP‐, LV.hARSA‐, and, indirectly, in LV.hGALC‐injected NHP at 3 months post‐treatment are not correlated to an immune response against transgenes or LV capsid proteins.…”

“…By comparing results from the two experimental systems, it appears that vector dose, injection in posterior white matter regions, and CED‐mediated delivery (Lonser et al , ), which allowed homogeneous and reproducible vector distribution, can be considered as factors that positively affect the extent of transduced volume and the enhancement of LV particle dispersion. The transduced brain volume in this study was overall lower when compared to that obtained following intracerebral AAV delivery (Colle et al , ; Rosenberg et al , ; Zerah et al , ). This can be explained by the multiple injection protocols (six injection sites with 6–12 deposits) used in those studies as compared to the two‐injection protocol in this study.…”

Glymphatic fluid transport controls paravascular clearance of AAV vectors from the brain

“…As mentioned earlier, preclinical studies with several naturally occurring AAV strains have established that CNS administration through intracranial or intrathecal routes often results in vector sequestration within peripheral organs such as the liver and spleen via systemic leakage (16–18, 34). Consistent with the notion that CSF-mediated glymphatic clearance removes solutes from the CNS, we observed a profound decrease in vector uptake and gene expression in off-target organs, such as the heart and liver, following intra-CSF administration in AQP4 −/− mice.…”

Gene therapy for metachromatic leukodystrophy

“…The spectrum of AAV serotypes was further expanded with the discovery of nonhuman primate AAV serotypes, including AAVs 8, 9, and rh.10 (Gao et al, ). Our initial studies with AAV‐mediated gene therapy for MLD were conducted with AAV5, and then, with the discovery of the nonhuman primate derived serotypes, our second‐generation studies were carried out with AAVrh.10 (Sondhi et al, , ; Piguet et al, ; Sondhi et al, ; Rosenberg et al, ). Our choice of AAVrh.10 was based on the successful use of this vector for treatment of the mouse model of late‐infantile neuronal ceroid lipofuscinosis (LINCL), another lysosomal storage disease, and the translation of these studies to a clinical study (Sondhi et al, , , ).…”