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Technical Insights into IND Success – GM1 Gangliosidosis
GM1 gangliosidosis is a rare neurodegenerative lysosomal storage disease caused by loss-of-function mutations in the β-gal gene encoding beta-galactosidase (GLB1). Infantile GM1 is the most common subtype in which GM1 accumulation drives rapid neurodegeneration beginning in the first 6 months of life, with survival of less than 5 years (1).
Prior studies demonstrated that adeno-associated virus (AAV) vectors can successfully transfer the Glb1 gene to neurons in murine and feline models, resulting in long-term expression of β-gal enzyme (2, 3). Moreover, studies in canine and feline models of other lysosomal storage diseases have shown that widespread gene transfer to the brain and spinal cord can be achieved via a single direct injection to the cerebrospinal fluid/CSF (4, 5).
Building on their extensive experience, the research team developed a CSF-delivered, AAV vector to treat GM1 gangliosidosis. They evaluated its impact on brain enzyme activity, lysosomal storage lesions, neurological signs, and survival in a murine disease model. Key study support was provided by Dr. Tami Goode, Senior Director, In Vivo Services, and members of the In Vivo Services Core, as well as the Histopathology and Vector Cores. An overview of critical techniques and data is provided below.
Intracerebroventricular (ICV) AAV Administration in Mice
Glb1 knockout mice (Glb1-/-) were obtained from the RIKEN BioResource Research Center (RBRC00690). Anesthetized one-month old Glb1-/- mice were injected with 5 µL of one of several AAVhu68.UbC.hGLB1 doses or vehicle (12 animals per group) into the lateral ventricle by a trained laboratory animal veterinarian.
All animals that received 4.4 x 1010 genome copies [GC] or higher survived to the 300-day study endpoint compared to vehicle-treated mice, whose survival ranged from 185 – 283 days.
Characterization of Murine Motor and Neurological Function
Motor function was assessed using the CatWalk XT gait analysis system (Noldus Information Technology). Additionally, a blinded examiner systematically evaluated nine different parameters (including gait, avoidance response, and limb positioning) to generate a standardized neurological score.
The shortened average stride length exhibited by vehicle-treated Glb1–/– mice compared to Glb1+/– controls was partially rescued by vector treatment, particularly in the two highest dose groups. Neurological abnormalities were not detected in the two highest dose groups, suggesting complete rescue of the neurological phenotype.
Quantification of Lysosomal Storage Lesions in the Brain
Lysosomal storage lesions were evaluated by staining coronal brain sections for lysosomal membrane protein LAMP1 (Abcam Ab24170) and quantitated using VisioPharm image analysis software.
Vector-treated animals exhibited a dose-dependent reduction in the proportion of LAMP1-positive cells compared to vehicle-treated Glb1–/– controls. The two highest vector doses (1.3 x 1011 GC or 4.4 x 1010 GC) reduced the proportion of LAMP1-positive cells to levels similar to those of normal vehicle-treated Glb1+/– controls. Lysosomal storage correction occurred within superficial and deep brain structures.
From the Bench to the Bedside
These preclinical studies supported the efficacy of a single cisterna magna AAVhu68 administration to treat infantile GM1 gangliosidosis. The investigational new drug (IND) application for the clinical candidate was approved in 2021 and advanced to a Phase 1/2 clinical trial in which the first patient was dosed in April 2021 (ClinicalTrials.Gov ID: NCT04713475). This is just one of many successes with which the team at Franklin Biolabs have been involved.
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Note
Adapted from Hinderer C, Nosratbakhsh B, Katz N, Wilson JM. A Single Injection of an Optimized Adeno-Associated Viral Vector into Cerebrospinal Fluid Corrects Neurological Disease in a Murine Model of GM1 Gangliosidosis. Hum Gene Ther. 2020 Nov;31(21-22):1169-1177. Epub 2020 Nov 2. PMID: 33045869
References
- Brunetti-Pierri N, Scaglia F. GM1 gangliosidosis: review of clinical, molecular, and therapeutic aspects. Mol Genet Metab. 2008 Aug;94(4):391-396. PMID: 18524657.
- Baek RC, Broekman ML, Leroy SG, Tierney LA, Sandberg MA, d’Azzo A, Seyfried TN, Sena-Esteves M. AAV-mediated gene delivery in adult GM1-gangliosidosis mice corrects lysosomal storage in CNS and improves survival. PLoS One. 2010 Oct 18;5(10):e13468. PMID: 20976108;
- McCurdy VJ, Johnson AK, Gray-Edwards HL, Randle AN, Brunson BL, Morrison NE, Salibi N, Johnson JA, Hwang M, Beyers RJ, Leroy SG, Maitland S, Denney TS, Cox NR, Baker HJ, Sena-Esteves M, Martin DR. Sustained normalization of neurological disease after intracranial gene therapy in a feline model. Sci Transl Med. 2014 Apr 9;6(231):231ra48. PMID: 24718858
- Gurda BL, De Guilhem De Lataillade A, Bell P, Zhu Y, Yu H, Wang P, Bagel J, Vite CH, Sikora T, Hinderer C, Calcedo R, Yox AD, Steet RA, Ruane T, O’Donnell P, Gao G, Wilson JM, Casal M, Ponder KP, Haskins ME. Evaluation of AAV-mediated Gene Therapy for Central Nervous System Disease in Canine Mucopolysaccharidosis VII. Mol Ther. 2016 Feb;24(2):206-216. PMID: 26447927.
- Hinderer C, Bell P, Gurda BL, Wang Q, Louboutin JP, Zhu Y, Bagel J, O’Donnell P, Sikora T, Ruane T, Wang P, Haskins ME, Wilson JM. Intrathecal gene therapy corrects CNS pathology in a feline model of mucopolysaccharidosis I. Mol Ther. 2014 Dec;22(12):2018-2027. PMID: 25027660.
