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Zanetti A, Tomanin R. Targeting Neurological Aspects of Mucopolysaccharidosis Type II: Enzyme Replacement Therapy and Beyond. BioDrugs 2024; 38:639-655. [PMID: 39177874 PMCID: PMC11358193 DOI: 10.1007/s40259-024-00675-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2024] [Indexed: 08/24/2024]
Abstract
Mucopolysaccharidosis type II (MPS II) is a rare, pediatric, neurometabolic disorder due to the lack of activity of the lysosomal hydrolase iduronate 2-sulfatase (IDS), normally degrading heparan sulfate and dermatan sulfate within cell lysosomes. The deficit of activity is caused by mutations affecting the IDS gene, leading to the pathological accumulation of both glycosaminoglycans in the lysosomal compartment and in the extracellular matrix of most body districts. Although a continuum of clinical phenotypes is described, two main forms are commonly recognized-attenuated and severe-the latter being characterized by an earlier and faster clinical progression and by a progressive impairment of central nervous system (CNS) functions. However, attenuated forms have also been recently described as presenting some neurological involvement, although less deep, such as deficits of attention and hearing loss. The main treatment for the disease is represented by enzyme replacement therapy (ERT), applied in several countries since 2006, which, albeit showing partial efficacy on some peripheral organs, exhibited a very poor efficacy on bones and heart, and a total inefficacy on CNS impairment, due to the inability of the recombinant enzyme to cross the blood-brain barrier (BBB). Together with ERT, whose design enhancements, performed in the last few years, allowed a possible brain penetration of the drug through the BBB, other therapeutic approaches aimed at targeting CNS involvement in MPS II were proposed and evaluated in the last decades, such as intrathecal ERT, intracerebroventricular ERT, ex vivo gene therapy, or adeno-associated viral vector (AAV) gene therapy. The aim of this review is to summarize the main clinical aspects of MPS II in addition to current therapeutic options, with particular emphasis on the neurological ones and on the main CNS-targeted therapeutic approaches explored through the years.
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Affiliation(s)
- Alessandra Zanetti
- Laboratory of Diagnosis and Therapy of Lysosomal Disorders, Department of Women's and Children's Health SDB, University of Padova, Via Giustiniani, 3, 35128, Padua, Italy
- Istituto di Ricerca Pediatrica Città della Speranza, 35127, Padua, Italy
| | - Rosella Tomanin
- Laboratory of Diagnosis and Therapy of Lysosomal Disorders, Department of Women's and Children's Health SDB, University of Padova, Via Giustiniani, 3, 35128, Padua, Italy.
- Istituto di Ricerca Pediatrica Città della Speranza, 35127, Padua, Italy.
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Smith MC, Belur LR, Karlen AD, Erlanson O, Furcich J, Lund TC, Seelig D, Kitto KF, Fairbanks CA, Kim KH, Buss N, McIvor RS. Comparative dose effectiveness of intravenous and intrathecal AAV9.CB7.hIDS, RGX-121, in mucopolysaccharidosis type II mice. Mol Ther Methods Clin Dev 2024; 32:101201. [PMID: 38374962 PMCID: PMC10875268 DOI: 10.1016/j.omtm.2024.101201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 01/24/2024] [Indexed: 02/21/2024]
Abstract
Mucopolysaccharidosis type II (MPS II) is an X-linked recessive lysosomal disease caused by iduronate-2-sulfatase (IDS) deficiency, leading to accumulation of glycosaminoglycans (GAGs) and the emergence of progressive disease. Enzyme replacement therapy is the only currently approved treatment, but it leaves neurological disease unaddressed. Cerebrospinal fluid (CSF)-directed administration of AAV9.CB7.hIDS (RGX-121) is an alternative treatment strategy, but it is unknown if this approach will affect both neurologic and systemic manifestations. We compared the effectiveness of intrathecal (i.t.) and intravenous (i.v.) routes of administration (ROAs) at a range of vector doses in a mouse model of MPS II. While lower doses were completely ineffective, a total dose of 1 × 109 gc resulted in appreciable IDS activity levels in plasma but not tissues. Total doses of 1 × 1010 and 1 × 1011 gc by either ROA resulted in supraphysiological plasma IDS activity, substantial IDS activity levels and GAG reduction in nearly all tissues, and normalized zygomatic arch diameter. In the brain, a dose of 1 × 1011 gc i.t. achieved the highest IDS activity levels and the greatest reduction in GAG content, and it prevented neurocognitive deficiency. We conclude that a dose of 1 × 1010 gc normalized metabolic and skeletal outcomes, while neurologic improvement required a dose of 1 × 1011 gc, thereby suggesting the prospect of a similar direct benefit in humans.
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Affiliation(s)
- Miles C. Smith
- Center for Genome Engineering, Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Lalitha R. Belur
- Center for Genome Engineering, Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Andrea D. Karlen
- Center for Genome Engineering, Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Olivia Erlanson
- Center for Genome Engineering, Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Justin Furcich
- Department of Pediatrics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Troy C. Lund
- Department of Pediatrics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Davis Seelig
- Comparative Pathology Shared Resource, University of Minnesota, St. Paul, MN 55455, USA
| | - Kelley F. Kitto
- Department of Pharmaceutics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Carolyn A. Fairbanks
- Department of Pharmaceutics, University of Minnesota, Minneapolis, MN 55455, USA
| | | | - Nick Buss
- REGENXBIO Inc., Rockville, MD 20850, USA
| | - R. Scott McIvor
- Center for Genome Engineering, Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
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