Five-year analysis of efficacy and safety of a bidirectional AAV gene therapy in Tay-Sachs sheep
Toloo Taghian, Jillian Gallagher, Stephanie Bertrand, William C. Baker, Kalajan Lopez Mercado, Hector R. Benatti, Erin Hall, Yvette Lopez, Abigail McElroy, John T. McCarthy, Sanjana Pulaparthi, Deborah Fernau, Samuel Mather, Sophia Esteves, Elise Diffie, Amanda Gross, Hannah G. Lahey, Xuntian Jiang, Elizabeth Parsley, Rachael Gately, Rachel Prestigiacomo, Siauna Johnson, Amanda Taylor, Lindsey Bierfeldt, Susan Tuominen, Jennifer Koehler, Guangping Gao, Jun Xie, Qin Su, Robert King, Matthew J. Gounis, Vania Anagnostakou, Ajit Puri, Ana Rita Batista, Miguel Sena-Esteves, Douglas R. Martin, Heather Gray-Edwards
Toloo Taghian, Jillian Gallagher, Stephanie Bertrand, William C. Baker, Kalajan Lopez Mercado, Hector R. Benatti, Erin Hall, Yvette Lopez, Abigail McElroy, John T. McCarthy, Sanjana Pulaparthi, Deborah Fernau, Samuel Mather, Sophia Esteves, Elise Diffie, Amanda Gross, Hannah G. Lahey, Xuntian Jiang, Elizabeth Parsley, Rachael Gately, Rachel Prestigiacomo, Siauna Johnson, Amanda Taylor, Lindsey Bierfeldt, Susan Tuominen, Jennifer Koehler, Guangping Gao, Jun Xie, Qin Su, Robert King, Matthew J. Gounis, Vania Anagnostakou, Ajit Puri, Ana Rita Batista, Miguel Sena-Esteves, Douglas R. Martin, Heather Gray-Edwards
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Five-year analysis of efficacy and safety of a bidirectional AAV gene therapy in Tay-Sachs sheep

Abstract

Tay-Sachs disease (TSD) and Sandhoff disease are fatal neurodegenerative diseases without an effective therapy that are caused by mutations in the HEXA and HEXB genes, respectively. Together they encode the heterodimeric isozyme of hexosaminidase, hexosaminidase A (HexA), that degrades GM2 ganglioside. This report describes a 5-year-long study using a bidirectional adeno-associated virus 9 (AAV9) vector (AAV9-Bic_HexA/HexB) encoding both HEXA and HEXB in the TSD sheep model. Bidirectional AAV9 was delivered i.v. or through various cerebrospinal fluid (CSF) delivery routes: intracerebroventricular (ICV), cisterna magna (CM), and lumbar intrathecal space (LIT). The longest survival and best distribution were achieved by multipoint CSF delivery (combined CM, ICV, and LIT) with treated animals that survived up to 5 years of age (untreated animals with TSD die after ~9 months). Extension in survival was accompanied by lasting improvement in neurological examination and maze testing. Improvement in biomarkers of efficacy, including MRI, magnetic resonance spectroscopy, diffusion tensor imaging, and CSF levels of GM2 ganglioside and HexA activity, was evident. Postmortem assessments showed broad HexA distribution, GM2 ganglioside clearance, and vector genome distribution, especially in deep brain structures. Therapeutic efficacy documented in this study supports translation of bidirectional vector and multipoint CSF delivery to a clinical trial in patients with TSD and Sandhoff disease.

Authors

Toloo Taghian, Jillian Gallagher, Stephanie Bertrand, William C. Baker, Kalajan Lopez Mercado, Hector R. Benatti, Erin Hall, Yvette Lopez, Abigail McElroy, John T. McCarthy, Sanjana Pulaparthi, Deborah Fernau, Samuel Mather, Sophia Esteves, Elise Diffie, Amanda Gross, Hannah G. Lahey, Xuntian Jiang, Elizabeth Parsley, Rachael Gately, Rachel Prestigiacomo, Siauna Johnson, Amanda Taylor, Lindsey Bierfeldt, Susan Tuominen, Jennifer Koehler, Guangping Gao, Jun Xie, Qin Su, Robert King, Matthew J. Gounis, Vania Anagnostakou, Ajit Puri, Ana Rita Batista, Miguel Sena-Esteves, Douglas R. Martin, Heather Gray-Edwards

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Figure 2

Noninvasive monitoring of bicistronic AAV9-treated TSD sheep.

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Noninvasive monitoring of bicistronic AAV9-treated TSD sheep. (A and B) ...
(A and B) HexA in CSF of short-term-treated sheep (n = 4 TSD+AAV_CSF-ICV-CM-LIT; pink hexagon-solid lines) shows a sharp increase to at least WT levels by 1 month after AAV administration (n = 10; gray circles). Similarly, there is a sharp decrease in GM2 levels into the normal range by 1 month after treatment. In the long-term-treated cohort (TSD+AAV_CSF-ICV-CM-LIT; red-dotted lines), GM2 shows a steady increase accompanied by an inversely proportional decrease in HexA levels approximately 1 year after AAV administration (each red symbol represents 1 sheep in the long-term cohort). Analyzed TSD (n = 14; black crosses). (C) T2-weighted MRI of sheep thalamus and cerebellum demonstrate normalization of white matter intensity (white arrow) in both TSD+AAV_IV and TSD+AAV_CSF_ICV-CM-LIT treated cohorts. (D) MRS in sheep thalamus indicates the normalization (no statistical difference from WT; n = 7) of markers of neuronal health, demyelination, and energy metabolism for the TSD+AAV_CSF_ICV-CM-LIT group (n = 4) and significantly different levels as compared with TSD sheep (*P < 0.05; n = 8 TSD sheep). TSD+AAV_IV (n = 3) and TSD+AAV_CSF_CM-LIT (n = 2) groups show intermediate levels. Brown-Forsythe and Welch’s ANOVA tests followed by Dunnett’s T3 test were performed. The data shown for MRS and DTI analysis in this figure represent 1-time imaging of each sheep at the endpoint. NAA, GPC + PCh, NAA+NAAG, Cr+PCr. (E) DTI scalar FA, which informs about the degree of anisotropy in diffusion of water in white matter, decreases significantly in TSD sheep as compared with WT sheep in the caudal internal capsule. AAV_IV and CSF cohorts show normalization on FA about 2–3 years after AAV administration (*P < 0.05). The Kruskal-Wallis test followed by Dunn’s test was performed. (F) FA scalar shows a negative and significant association with GM2 levels in sheep CSF (P = 0.0028). Spearman’s test was used for correlation analysis.