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1.
Mol Ther ; 29(11): 3230-3242, 2021 11 03.
Article in English | MEDLINE | ID: mdl-33775910

ABSTRACT

Fabry disease, a lysosomal storage disorder resulting from the deficient activity of α-galactosidase A (α-Gal A), is characterized by cardiac, renal, and/or cerebrovascular disease due to progressive accumulation of the enzyme's substrates, globotriaosylceramide (Gb3) and globotriaosylsphingosine (Lyso-Gb3). We report here the preclinical evaluation of liver-targeted in vivo genome editing using zinc-finger nuclease (ZFN) technology to insert the human α-galactosidase A (hGLA) cDNA into the albumin "safe harbor" locus of Fabry mice, thereby generating an albumin-α-Gal A fusion protein. The mature α-Gal A protein is secreted into the circulation for subsequent mannose-6-phosphate receptor-mediated tissue uptake. Donor vector optimization studies showed that replacing the hGLA cDNA signal peptide sequence with that of human iduronate 2-sulfatase (IDS) achieved higher transgene expression. Intravenous adeno-associated virus (AAV) 2/8-mediated co-delivery of the IDS-hGLA donor and ZFNs targeting the albumin locus resulted in continuous, supraphysiological plasma and tissue α-Gal A activities, which essentially normalized Gb3 and Lyso-Gb3 levels in key tissues of pathology. Notably, this was achieved with <10% of hepatocytes being edited to express hGLA, occurring mostly via non-homologous end joining (NHEJ) rather than homology-directed repair (HDR). These studies indicate that ZFN-mediated in vivo genome editing has the potential to be an effective one-time therapy for Fabry disease.


Subject(s)
Fabry Disease/genetics , Fabry Disease/therapy , Gene Editing , Hepatocytes/metabolism , Zinc Finger Nucleases/metabolism , alpha-Galactosidase/genetics , alpha-Galactosidase/metabolism , Animals , Dependovirus/genetics , Disease Models, Animal , Enzyme Activation , Gene Expression , Gene Transfer Techniques , Genetic Engineering , Genetic Therapy , Genetic Vectors/genetics , Humans , Mice , Transgenes
2.
Mol Ther Methods Clin Dev ; 18: 607-619, 2020 Sep 11.
Article in English | MEDLINE | ID: mdl-32775495

ABSTRACT

Fabry disease is an X-linked lysosomal storage disorder caused by mutations in the alpha-galactosidase A (GLA) gene, which encodes the exogalactosyl hydrolase, alpha-galactosidase A (α-Gal A). Deficient α-Gal A activity results in the progressive, systemic accumulation of its substrates, globotriaosylceramide (Gb3) and globotriaosylsphingosine (Lyso-Gb3), leading to renal, cardiac, and/or cerebrovascular disease and early demise. The current standard treatment for Fabry disease is enzyme replacement therapy, which necessitates lifelong biweekly infusions of recombinant enzyme. A more long-lasting treatment would benefit Fabry patients. Here, a gene therapy approach using an episomal adeno-associated viral 2/6 (AAV2/6) vector that encodes the human GLA cDNA driven by a liver-specific expression cassette was evaluated in a Fabry mouse model that lacks α-Gal A activity and progressively accumulates Gb3 and Lyso-Gb3 in plasma and tissues. A detailed 3-month pharmacology and toxicology study showed that administration of a clinical-scale-manufactured AAV2/6 vector resulted in markedly increased plasma and tissue α-Gal A activities, and essentially normalized Gb3 and Lyso-Gb3 at key sites of pathology. Further optimization of vector design identified the clinical lead vector, ST-920, which produced several-fold higher plasma and tissue α-Gal A activity levels with a good safety profile. Together, these studies provide the basis for the clinical development of ST-920.

3.
Mol Ther ; 27(1): 178-187, 2019 01 02.
Article in English | MEDLINE | ID: mdl-30528089

ABSTRACT

Mucopolysaccharidosis type I (MPS I) is a severe disease due to deficiency of the lysosomal hydrolase α-L-iduronidase (IDUA) and the subsequent accumulation of the glycosaminoglycans (GAG), leading to progressive, systemic disease and a shortened lifespan. Current treatment options consist of hematopoietic stem cell transplantation, which carries significant mortality and morbidity risk, and enzyme replacement therapy, which requires lifelong infusions of replacement enzyme; neither provides adequate therapy, even in combination. A novel in vivo genome-editing approach is described in the murine model of Hurler syndrome. A corrective copy of the IDUA gene is inserted at the albumin locus in hepatocytes, leading to sustained enzyme expression, secretion from the liver into circulation, and subsequent uptake systemically at levels sufficient for correction of metabolic disease (GAG substrate accumulation) and prevention of neurobehavioral deficits in MPS I mice. This study serves as a proof-of-concept for this platform-based approach that should be broadly applicable to the treatment of a wide array of monogenic diseases.


Subject(s)
Gene Editing/methods , Genetic Therapy/methods , Mucopolysaccharidosis I/therapy , Zinc Finger Nucleases/metabolism , Animals , Disease Models, Animal , Enzyme Replacement Therapy , Female , Glycosaminoglycans/metabolism , Iduronidase/metabolism , Lysosomal Storage Diseases/drug therapy , Lysosomal Storage Diseases/metabolism , Lysosomal Storage Diseases/therapy , Male , Mice , Mucopolysaccharidosis I/drug therapy , Mucopolysaccharidosis I/metabolism , Zinc Finger Nucleases/genetics
4.
Mol Ther ; 26(4): 1127-1136, 2018 04 04.
Article in English | MEDLINE | ID: mdl-29580682

ABSTRACT

Mucopolysaccharidosis type II (MPS II) is an X-linked recessive lysosomal disorder caused by deficiency of iduronate 2-sulfatase (IDS), leading to accumulation of glycosaminoglycans (GAGs) in tissues of affected individuals, progressive disease, and shortened lifespan. Currently available enzyme replacement therapy (ERT) requires lifelong infusions and does not provide neurologic benefit. We utilized a zinc finger nuclease (ZFN)-targeting system to mediate genome editing for insertion of the human IDS (hIDS) coding sequence into a "safe harbor" site, intron 1 of the albumin locus in hepatocytes of an MPS II mouse model. Three dose levels of recombinant AAV2/8 vectors encoding a pair of ZFNs and a hIDS cDNA donor were administered systemically in MPS II mice. Supraphysiological, vector dose-dependent levels of IDS enzyme were observed in the circulation and peripheral organs of ZFN+donor-treated mice. GAG contents were markedly reduced in tissues from all ZFN+donor-treated groups. Surprisingly, we also demonstrate that ZFN-mediated genome editing prevented the development of neurocognitive deficit in young MPS II mice (6-9 weeks old) treated at high vector dose levels. We conclude that this ZFN-based platform for expression of therapeutic proteins from the albumin locus is a promising approach for treatment of MPS II and other lysosomal diseases.


Subject(s)
Energy Metabolism , Gene Dosage , Gene Editing , Iduronate Sulfatase/genetics , Mucopolysaccharidosis II/genetics , Mucopolysaccharidosis II/metabolism , Phenotype , Animals , Biomarkers , Disease Models, Animal , Endonucleases/genetics , Endonucleases/metabolism , Enzyme Activation , Gene Transfer Techniques , Hepatocytes/metabolism , Introns , Mice , Mucopolysaccharidosis II/pathology , Mucopolysaccharidosis II/physiopathology , Zinc Fingers/genetics
5.
Blood ; 126(15): 1777-84, 2015 Oct 08.
Article in English | MEDLINE | ID: mdl-26297739

ABSTRACT

Site-specific genome editing provides a promising approach for achieving long-term, stable therapeutic gene expression. Genome editing has been successfully applied in a variety of preclinical models, generally focused on targeting the diseased locus itself; however, limited targeting efficiency or insufficient expression from the endogenous promoter may impede the translation of these approaches, particularly if the desired editing event does not confer a selective growth advantage. Here we report a general strategy for liver-directed protein replacement therapies that addresses these issues: zinc finger nuclease (ZFN) -mediated site-specific integration of therapeutic transgenes within the albumin gene. By using adeno-associated viral (AAV) vector delivery in vivo, we achieved long-term expression of human factors VIII and IX (hFVIII and hFIX) in mouse models of hemophilia A and B at therapeutic levels. By using the same targeting reagents in wild-type mice, lysosomal enzymes were expressed that are deficient in Fabry and Gaucher diseases and in Hurler and Hunter syndromes. The establishment of a universal nuclease-based platform for secreted protein production would represent a critical advance in the development of safe, permanent, and functional cures for diverse genetic and nongenetic diseases.


Subject(s)
Albumins/genetics , Enzyme Replacement Therapy , Genetic Therapy , Genome , Liver/metabolism , Transgenes/physiology , Albumins/metabolism , Animals , Dependovirus/genetics , Endonucleases , Fabry Disease/genetics , Fabry Disease/therapy , Factor IX/genetics , Factor VIII/genetics , Gaucher Disease/genetics , Gaucher Disease/therapy , Genetic Vectors/administration & dosage , Hemophilia A/genetics , Hemophilia A/therapy , Hemophilia B/genetics , Hemophilia B/therapy , High-Throughput Nucleotide Sequencing , Humans , Lysosomes/enzymology , Mice , Mice, Inbred C57BL , Mucopolysaccharidosis I/genetics , Mucopolysaccharidosis I/therapy , Mucopolysaccharidosis II/genetics , Mucopolysaccharidosis II/therapy , Promoter Regions, Genetic/genetics , RNA Editing , RNA, Messenger/genetics , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , Zinc Fingers
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