(19)
(11)EP 3 913 060 A1

(12)EUROPEAN PATENT APPLICATION

(43)Date of publication:
24.11.2021 Bulletin 2021/47

(21)Application number: 20305540.5

(22)Date of filing:  22.05.2020
(51)International Patent Classification (IPC): 
C12N 15/86(2006.01)
(52)Cooperative Patent Classification (CPC):
C12N 9/16; C12N 15/86; C12N 2830/008; C12N 2750/14171; C12Y 301/03009; C12N 2750/14143; C07K 14/8125
(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated Extension States:
BA ME
Designated Validation States:
KH MA MD TN

(71)Applicants:
  • Genethon
    91000 Evry (FR)
  • Institut National de la Santé et de la Recherche Médicale
    75013 Paris (FR)
  • Universite d'Evry Val d'Essonne
    91000 Evry (FR)
  • UNIVERSITE CLAUDE BERNARD - LYON 1
    69100 Villeurbanne (FR)

(72)Inventor:
  • The designation of the inventor has not yet been filed
     ()

(74)Representative: Cabinet Beau de Loménie 
158, rue de l'Université
75340 Paris Cedex 07
75340 Paris Cedex 07 (FR)


(56)References cited: : 
  
      


    (54)VECTORS ENCODING A GLUCOSE-6-PHOSPHATASE (G6PASE-A) FOR GENE THERAPY


    (57) The invention relates to a nucleic acid construct for the expression of a glucose-6-phosphatase-a (G6Pase-a) in a cell, the construct comprising a nucleic acid sequence encoding the G6Pase-a, wherein the nucleic acid sequence encoding the G6Pase-a is operably linked to a human alpha-1 antitrypsin (hAAT) promoter, a vector comprising the nucleic acid construct of the invention, a cell transformed with the nucleic acid construct or the vector of the invention, a composition comprising the nucleic acid construct, the vector or the cell of the invention, and the use thereof.


    Description

    Field of the invention



    [0001] The invention relates to a nucleic acid construct for the expression of a glucose-6-phosphatase-a (G6Pase-a) in a cell, a vector comprising the nucleic acid construct useful in the treatment of glycogen storage disease Ia (GSD-Ia), wherein the nucleic acid sequence encoding the G6Pase-a is operably linked to a human alpha-1 antitrypsin (hAAT) promoter.

    Background of the invention



    [0002] Glycogen storage disease type la (GSD-Ia or von Gierke disease) is caused by a deficiency in glucose-6-phosphatase-a (G6Pase-a), an enzyme that is expressed primarily in the liver, kidney, and intestine. G6Pase-a, encoded by the G6PC gene, is a hydrophobic protein anchored in the endoplasmic reticulum (ER) by nine transmembrane helices. This enzyme catalyzes the hydrolysis of glucose-6-phosphate (G6P) to glucose and inorganic phosphate in the terminal step of glycogenolysis and gluconeogenesis. Patients affected by GSD-Ia are unable to maintain glucose homeostasis and present with fasting hypoglycemia, growth retardation, hepatomegaly, nephromegaly, hyperlipidemia, hyperuricemia, and lactic academia.

    [0003] Most of the time, hypoglycemia can be managed using dietary therapies that enable patients to attain near normal growth and pubertal development. However, the long-term clinical complications, and their underlying pathological processes, remain uncorrected. One of the most significant chronic risks is hepatocellular adenoma (HCA), that develops in 70-80% of GSD-I patients over 25 year-old. HCAs in GSD-Ia patients are multiple and non-encapsulated, with complications including local compression and intratumoral hemorrhage. In 10% of GSD-Ia patients, HCAs undergo malignant transformation to hepatocellular carcinoma (HCC).

    [0004] Thus, a need exists for an improved therapy vector for the treatment of GSD-Ia and its associated complications.

    [0005] Gene therapy studies using recombinant adeno-associated virus (AAV) carrying G6Pase-a have previously been performed in animal models of GSD-Ia. In particular, the prior art discloses the use of nucleic acid constructs comprising a nucleic acid sequence encoding the G6Pase-a which is operably linked to a G6PC promoter/enhancer (GPE).

    [0006] Complications of treatment related to immune responses against the vector represent serious obstacles for the use of AAV vectors in gene therapy. The administration of lower doses of AAV vectors is, in general, associated to a lower activation of the immune response and a better stability of transgene expression [15]. In order to decrease the appearance of side effects associated with the use of AAV vectors, it is therefore preferable to administer the lowest amount of AAV vector that is sufficient to obtain a therapeutically effective effect in a subject.

    [0007] Thus, there is a need for improved nucleic acid constructs that increases G6Pase-a expression and activity in gene therapy, allowing to decrease the amount of AAV vector that is necessary to achieve a therapeutic effect in a subject.

    Summary of the invention



    [0008] The inventors have surprisingly shown that, in particular in an AAV gene therapy setting, a nucleic acid encoding G6Pase-a under the control of a hAAT promoter leads to increased G6Pase-a expression and G6Pase-a activity that permits phenotypical rescue in GSDIa mice compared to hGPE promoter. This was particularly unexpected in view of the prior art that used different forms of G6Pase native promoter (GPE) derived from different species to treat GSDIa.

    [0009] In addition, the inventors have also shown that the same nucleic acid encoding G6Pase-a under the control of a hAAT promoter decreases the risk of tumor formation, such as HCA and HCC, when compared to hGPE promoter in gene therapy. This was also particularly unexpected in view of the prior art that predicts that promoters with higher activity are more likely to increase the risk of HCA and HCC after gene therapy [1].

    [0010] Thus, in a first aspect, the invention relates to a nucleic acid construct for the expression of a glucose-6-phosphatase-a (G6Pase-a) in a cell, the construct comprising a nucleic acid sequence encoding the G6Pase-a, wherein the nucleic acid sequence encoding the G6Pase-a is operably linked to a human alpha-1 antitrypsin (hAAT) promoter.

    [0011] In a second aspect, the invention relates to a vector comprising the nucleic acid construct of the invention.

    [0012] In a third aspect, the invention relates to a cell transformed with the nucleic acid molecule of the invention or the vector of the invention.

    [0013] In a fourth aspect, the invention relates to a composition comprising the nucleic acid molecule of the invention, the vector of the invention, or the cell of the invention.

    [0014] In a fifth aspect, the invention relates to the nucleic acid construct, the vector, the cell or the composition of the invention, for use as a medicament, in particular for use in the treatment of glycogen storage disease Ia (GSD-Ia).

    Legends to the figures



    [0015] 

    Figure 1 shows the correction of the liver phenotype in GSD-Ia mice and WT mice after 15 days of treatment with AAV vectors or PBS. A. is the scheme of the protocol. B. shows the glycemia measured after 6h of fasting at the end of the protocol. C. shows G6Pase activity measured in liver tissues. D. shows glycogen content of liver tissues. E. shows hepatomegaly reported as the percentage of liver/body weight. F. shows the vector genome copy number per diploid genome measured in liver of AAV-treated mice. Statistical analyses were performed by ANOVA in A-E (# P<0.05 vs. PBS-injected L.G6pc+/+ mice; * P<0.05 vs. PBS-injected L.G6pc-/- mice) and by t-test in F (ns, not significant).

    Figure 2 shows the long-term correction of the liver phenotype in GSD-Ia mice. A. represents the scheme of the protocol. B. shows the glycemia measured after 6h of fasting at the end of the protocol, i.e. 7 months after vector injection. C. shows the G6Pase activity measured in liver tissues collected at sacrifice. D. shows the glycogen content measured on liver tissues. E. shows the hepatomegaly reported as the percentage of liver/body weight at sacrifice. F. shows the vector genome copy number per diploid genome measured in liver of AAV-treated mice. Statistical analyses were performed by ANOVA (# P<0.05 vs. PBS-injected L.G6pc+/+ mice; * P<0.05 vs. PBS-injected L.G6pc-/- mice; † P<0.05 as indicated) and by t-test in F (* P<0.05).

    Figure 3 shows that hGPE-directed gene therapy promotes hepatic tumor formation in L.G6pc-/- mice fed a high fat high sucrose diet. A. represents the scheme of the protocol. B. shows the glycemia measured after 6h of fasting at the end of the protocol i.e. 8 months after vectors injection. C. shows the G6Pase-a activity assay performed on liver tissues collected at sacrifice. D. shows the vector genome copy number per diploid genome measured in liver. E. shows the number of tumors larger than 2 mm observed in PBS or AAV vector -treated L.G6pc-/- mice 9 months after the start of the HF/HS regimen. Statistical analyses were performed by ANOVA in B and C (# P<0.05 vs. PBS-injected L.G6pc+/+ mice; * P<0.05 vs. PBS-injected L.G6pc-/- mice), by t-test in D (ns, not significant) and by non-parametric ANOVA in E (* P<0.05 vs. PBS-injected L.G6pc+/+ mice).


    Detailed description of the invention


    Definitions



    [0016] The terms "glucose-6-phosphatase alpha" or "G6Pase-a" relates to an enzyme encoded by the G6pc gene. This enzyme catalyzes the hydrolysis of glucose-6-phosphate (G6P) to glucose and inorganic phosphate in the terminal step of glycogenolysis and gluconeogenesis. According to the invention, G6Pase-a may be a wild-type G6Pase-a or a modified G6Pase-a, in particular a modified G6Pase-a having increased phosphohydrolase activity. Modified G6Pase-a are disclosed in WO2016106303 and [16]. For example, G6Pase-a may be SEQ ID NO: 1, SEQ ID NO: 12, or any the modified G6Pase-a having an amino acid sequence selected from SEQ ID NO: 29 to SEQ ID NO: 44.

    [0017] According to the present invention, the "identity" is calculated by comparing two aligned sequences in a comparison window. The alignment of the sequences makes it possible to determine the number of positions (nucleotides or amino acids) in common for the two sequences in the comparison window. The number of positions in common is therefore divided by the total number of positions in the comparison window and multiplied by 100 to obtain the percentage of identity. The determination of the percentage of sequence identity can be carried out manually or by means of well-known computer programs. In a particular embodiment of the invention, the identity or the homology corresponds to at least one substitution, for example 1, 2, 3, 4, 5 substitutions, of an amino acid residue, without appreciable loss of interactive binding capacity. Preferably, the at least one substitution is a conservative amino acid substitution. By "conservative amino acid substitution", it is meant that an amino acid can be replaced with another amino acid having a similar side chain. Families of amino acid having similar side chains have been defined in the art, including basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., glycine, cysteine, alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine).

    [0018] According to the invention, the term "nucleic acid sequence" refers to a DNA or RNA molecule in single or double stranded form, particularly a DNA.

    [0019] According to the invention, the term "nucleic acid sequence encoding a G6Pase-a" refers to a nucleic acid sequence encoding a G6Pase-a, either a wild-type G6Pase-a or a modified G6Pase-a. Modified nucleic acid sequence encoding a modified G6Pase-a are disclosed in reference [16] and WO2016106303. For example, a nucleic acid sequence encoding a wild-type G6Pase-a have the nucleotide sequence SEQ ID NO: 2 or SEQ ID NO: 3. For example, a nucleic acid sequence encoding a modified G6Pase-a have the nucleotide sequence SEQ ID NO: 4. For example, a nucleic acid sequence encoding a G6Pase-a may therefore be SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, or any of the nucleic acid sequences encoding a modified G6Pase-a selected from SEQ ID NO: 13 to SEQ ID NO: 28.

    [0020] The term "nucleic acid construct" refers to an artificially constructed segment of nucleic acid that is to be transplanted into a target cell for expressing a transgene, e.g. for the expression of a G6Pase-a in a cell. The nucleic acid construct may comprise one or more expression control nucleic acid sequences and/or other nucleic acid sequences improving the expression of G6Pase-a and/or nucleic acid sequences enhancing the secretion of G6Pase-a and/or nucleic acid sequences enhancing the tissue uptake of G6Pase-a, said nucleic acid sequences may be operably linked to the sequence encoding the transgene (e.g. G6Pase-a). As used herein, the term "operably linked" refers to a linkage of polynucleotide elements in a functional relationship. A nucleic acid sequence is "operably linked" when it is placed into a functional relationship with another nucleic acid sequence. For instance, a promoter, or another transcription regulatory nucleic acid sequence, is operably linked to a nucleic acid sequence encoding a transgene (e.g. G6Pase-a) if it affects the transcription of the nucleic acid sequence. Such expression control nucleic acid sequences are known in the art, such as promoters, enhancers (such as cis-regulatory modules (CRMs)), introns, polyA signals, etc.

    [0021] The term "alpha-1 antitrypsin" or "AAT" relates to a protein belonging to the serpin superfamily. It is encoded in humans by the SERPINA1 gene. The term "hAAT" relates to the human AAT.

    [0022] The term "promoter" refers to a region of DNA that directs/initiates transcription of a nucleic acid sequence (e.g. a gene). A promoter includes necessary nucleic acid sequences near the start site of transcription. Typically, promoters are located near the genes they transcribe. The term "hAAT promoter" relates to the promoter of hAAT, either a wild-type hAAT promoter or a modified hAAT promoter.

    [0023] The term "vector" according to the invention means a vector suitable for a transgene expression in gene therapy, e.g. for G6Pase-a expression in gene therapy.

    [0024] In the context of the present invention, the term "gene therapy" refers to treatment of a subject which involves delivery of a gene / nucleic acid into an individual's cells for the purpose of treating a disease.

    [0025] The term "subject", "patient" or "individual", as used herein, refers to a human or non-human mammal (such as a rodent (mouse, rat), a feline, a canine, or a primate) affected or likely to be affected with a glycogen storage disease Ia (GSD-Ia). Preferably, the subject is a human, man or woman.

    [0026] The term "glycogen storage disease" or "GSD" refers to a metabolic disorder caused by enzyme deficiencies affecting glycogen synthesis, glycogen breakdown or glycolysis, typically within muscles and/or liver cells. GSD is classified in different types, from GSD type 0 to GSD type XV. GSD-I consists of two autosomal recessive disorders, GSD-Ia and GSD-Ib. GSD-Ia results from a deficiency in glucose-6-phosphatase-a. Deficiencies in the glucose-6-phosphate transporter (G6PT) are responsible for GSD-Ib. According to the invention, the GSD is GSD-Ia (von Gierke's disease; OMIM # 232240).

    [0027] The term "treating" or "treatment" means reversing, alleviating, inhibiting the progress of, or preventing the disorder or condition to which such term applies, or one or more symptoms of such disorder or condition. In particular, the treatment of the disorder may consist in treating dysfunctions in GSD, preferably improving the glycaemia control in a subject.

    [0028] The term "pharmaceutically acceptable" means approved by a regulatory agency of the Federal or a state government or listed in the U.S. or European Pharmacopeia or other generally recognized pharmacopeia for use in animals and Humans.

    [0029] A "pharmaceutical composition" means a composition comprising pharmaceutically acceptable carrier. For example, a carrier can be a diluent, adjuvant, excipient, or vehicle with which the therapeutic is administered. Such pharmaceutical carriers can be sterile liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. Water is a preferred carrier when the pharmaceutical composition is administered intravenously. Saline solutions and aqueous dextrose and glycerol solutions can also be employed as liquid carriers, particularly for injectable solutions. Suitable pharmaceutical excipients include starch, glucose, lactose, sucrose, sodium stearate, glycerol monostearate, talc, sodium chloride, dried skim milk, glycerol, propylene glycol, water, ethanol and the like. When the pharmaceutical composition is adapted for oral administration, the tablets or capsules can be prepared by conventional means with pharmaceutically acceptable excipients such as binding agents (e.g. pregelatinized maize starch, polyvinylpyrrolidone or hydroxypropyl methylcellulose); fillers (e.g., lactose, microcrystalline cellulose or calcium hydrogen phosphate); lubricants (e.g., magnesium stearate, talc or silica); disintegrants (e.g., potato starch or sodium starch glycolate); or wetting agents (e.g., sodium lauryl sulphate). The tablets may be coated by methods well known in the art. Liquid preparations for oral administration may take the form of, for example, solutions, syrups or suspensions, or they may be presented as a dry product for constitution with water or another suitable vehicle before use. Such liquid preparations may be prepared by conventional means with pharmaceutically acceptable additives such as suspending agents (e.g., sorbitol syrup, cellulose derivatives or hydrogenated edible fats); emulsifying agents (e.g., lecithin or acacia); non-aqueous vehicles (e.g., almond oil, oily esters, ethyl alcohol or fractionated vegetable oils); and preservatives (e.g., methyl or propyl-p- hydroxybenzoates or sorbic acid). The preparations may also contain buffer salts, flavoring, coloring and sweetening agents as appropriate. The composition according to the invention is preferably a pharmaceutical composition.

    Nucleic acid construct



    [0030] The invention relates to a nucleic acid construct for the expression of a glucose-6-phosphatase (G6Pase-a) in a cell, the construct comprising a nucleic acid sequence encoding the G6Pase-a, wherein the nucleic acid sequence encoding the G6Pase-a is operably linked to a human alpha-1 antitrypsin (hAAT) promoter.

    [0031] According to the invention, the nucleic acid sequence may encode a wild-type G6Pase-a, e.g. the G6Pase-a having the amino acid sequence SEQ ID NO: 1, or a modified G6Pase-a, preferably a modified G6Pase-a having increased phosphohydrolase activity, e.g. a G6Pase-a comprising or having an amino acid sequence at least 90% identical to SEQ ID NO: 1. The modified G6Pase-a can include one or more amino acid modification(s), such as substitution or deletion, so long as the protein retains enzymatic activity. In some embodiments, the modified G6Pase-a comprises a serine to cysteine substitution at amino acid 298 of human G6Pase-a (the amino acid sequence of wild type human G6Pase-a is set forth herein as SEQ ID NO: 1). The modified G6Pase-a can include modifications at other residues so long as the protein retains enzymatic activity. For example, the modified G6Pase-a can include substitutions at other residues, such residues include positions 3, 54, 139, 196, 199, 242, 247, 292, 301, 318, 324, 332, 347, 349, 350 and/or 353 of the human G6Pase-a (set forth as SEQ ID NO: 1). Modified G6Pase-a are disclosed in WO2016/106303 and [16]. For example, G6Pase-a may be SEQ ID NO: 1, SEQ ID NO: 12, or any modified G6Pase-a having an amino acid sequence selected from SEQ ID NO: 13 to SEQ ID NO: 28.

    [0032] In some embodiments, the G6Pase-a comprises or has an amino acid sequence at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to SEQ ID NO: 1.

    [0033] The nucleic acid sequence encoding the G6Pase-a may therefore encode either a wild-type G6Pase-a or a modified G6Pase-a. Nucleic acid sequence encoding a modified G6Pase-a may be any of the nucleic acid sequences selected from SEQ ID NO: 29 to SEQ ID NO: 44.

    [0034] In some embodiments, the nucleic acid sequence encoding the G6Pase-a comprises a nucleotide sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity with SEQ ID NO: 2.

    [0035] For example, a nucleic acid sequence encoding a G6Pase-a may therefore be SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, or any of nucleic acid sequences n°6-7 of WO2016106303.

    [0036] The nucleic acid sequence encoding a G6Pase-a is operably linked to a human alpha-1 antitrypsin (hAAT) promoter.

    [0037] According to the invention, the hAAT promoter may be a wild-type hAAT promoter, e.g. the hAAT promoter having the nucleic acid sequence SEQ ID NO: 8, or a modified hAAT promoter, e.g. a hAAT promoter comprising or having an amino acid sequence at least 90% identical to SEQ ID NO: 8. The modified hAAT promoter can include one or more amino acid modification(s), such as substitution or deletion, so long as the promoter still directs/initiates transcription of the G6Pase-a.

    [0038] In some embodiments, the hAAT promoter comprises or has a nucleotide sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity with SEQ ID NO: 8.

    [0039] In a particular embodiment, the nucleic acid construct comprises an intron, in particular an intron placed between the hAAT promoter and the nucleic acid sequence encoding a G6Pase-a. An intron may be introduced to increase mRNA stability and the production of G6Pase-a.

    [0040] In a particular embodiment, the nucleic acid construct of the invention comprises, in the 5' to 3' orientation, the hAAT promoter optionally preceded by an enhancer, such as ApoE enhancer (e.g. SEQ ID NO: 9), the nucleic acid sequence encoding the G6Pase-a and a polyadenylation signal (such as the bovine growth hormone polyadenylation signal, the HBB2 polyadenylation signal, the SV40 polyadenylation signal, or another naturally occurring or artificial polyadenylation signal). In a particular embodiment, the nucleic acid construct of the invention comprises, in the 5' to 3' orientation, the hAAT promoter optionally preceded by an enhancer, such as ApoE enhancer (e.g. SEQ ID NO: 9), an intron (in particular an intron as defined above), a nucleic acid molecule encoding the G6Pase-a, and a polyadenylation signal.

    [0041] In a particular embodiment, the nucleic acid construct comprises or has a nucleotide sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity with SEQ ID NO: 7 or SEQ ID NO: 11.

    [0042] The term nucleic acid construct is to be transferred into a target cell for the expression of a G6Pase-a in said cell. Preferably, said target cell is a liver cell, a kidney cell or an intestinal cell.

    Vector



    [0043] The invention also relates to a vector comprising the nucleic acid construct of the invention.

    [0044] In some embodiments, the vector is a plasmid vector. In another embodiment, the vector is a nanoparticle containing the nucleic acid construct of the invention. In another embodiment, the vector is a system based on transposons, allowing integration of the nucleic acid construct of the invention in the genome of the target cell, such as the hyperactive Sleeping Beauty (SB100X) transposon system [2]. In another embodiment, the vector is a viral vector suitable for gene therapy. The vector may target any cell of interest such as liver cells, kidney cells or intestinal cells.

    [0045] In a preferred embodiment, the vector is a viral vector, such as lentiviral vector or adeno-associated virus (AAV) vector, preferably an AAV vector. In a particularly preferred embodiment, the AAV vector implemented in the practice of the present invention is AAV8 or AAV9, preferably AAV8.

    [0046] Thus, the nucleic acid construct of the invention may also contain sequences suitable for producing an efficient viral vector, as it is well disclosed in the art. In a preferred embodiment, the nucleic acid construct is inserted in a retroviral vector, such as a lentiviral vector, or an AAV vector, such as a single-stranded or double-stranded self-complementary AAV vector. In a much preferred embodiment of the present invention, the viral vector is an AAV vector, such as an AAV vector suitable for transducing liver cells, more particularly an AAV-1, AAV-2 and AAV-2 variants (such as the quadruple-mutant capsid optimized AAV-2 comprising an engineered capsid with Y44+500+730F+T491V changes, disclosed in [3]), AAV-3 and AAV-3 variants (such as the AAV3-ST variant comprising an engineered AAV-3 capsid with two amino acid changes, S663V+T492V, disclosed in Vercauteren et al. [4], AAV-3B and AAV-3B variants, AAV-4, AAV-5, AAV-6 and AAV-6 variants (such as the AAV-6 variant comprising the triply mutated AAV-6 capsid Y731F/Y705F/T492V form disclosed in [5], AAV-7, AAV-8, AAV-9, AAV-10 such as AAV-cy10 and AAV-rh10, AAV-rh74, AAV-dj, Anc80, LK03, AAV-2i8, porcine AAV serotypes such as AAV-po4 and AAV-po6, etc., vector or a retroviral vector such as a lentiviral vector and an alpha-retrovirus. As it is known in the art, depending on the specific viral vector considered for use, additional suitable sequences will be introduced in the nucleic acid construct of the invention for obtaining a functional viral vector. Suitable sequences include AAV ITRs for an AAV vector, or LTRs for lentiviral vectors. As such, the invention also relates to a nucleic acid construct as described above, flanked by an ITR or an LTR on each side.

    [0047] In addition, other non-natural engineered variants and chimeric AAV can also be useful. AAV viruses may be engineered using conventional molecular biology techniques, making it possible to optimize these particles for cell specific delivery of nucleic acid sequences, for minimizing immunogenicity, for tuning stability and particle lifetime, for efficient degradation, for accurate delivery to the nucleus. Desirable AAV fragments for assembly into vectors include the cap proteins, including the vp1, vp2, vp3 and hypervariable regions, the rep proteins, including rep 78, rep 68, rep 52, and rep 40, and the sequences encoding these proteins. These fragments may be readily utilized in a variety of vector systems and host cells. AAV-based recombinant vectors lacking the Rep protein integrate with low efficacy into the host's genome and are mainly present as stable circular episomes that can persist for years in the target cells. Alternatively to using AAV natural serotypes, artificial AAV serotypes may be used in the context of the present invention, including, without limitation, AAV with a non-naturally occurring capsid protein. Such an artificial capsid may be generated by any suitable technique, using a selected AAV sequence (e.g., a fragment of a vp1 capsid protein) in combination with heterologous sequences which may be obtained from a different selected AAV serotype, non-contiguous portions of the same AAV serotype, from a non-AAV viral source, or from a non-viral source. An artificial AAV serotype may be, without limitation, a chimeric AAV capsid, a recombinant AAV capsid, or a "humanized" AAV capsid.

    [0048] In the context of the present invention, the AAV vector comprises an AAV capsid able to transduce the target cells of interest, in particular hepatocytes. In a further particular embodiment, the AAV vector is a pseudotyped vector, i.e. its genome and capsid are derived from AAVs of different serotypes. For example, the pseudotyped AAV vector may be a vector whose genome is derived from one of the above mentioned AAV serotypes, and whose capsid is derived from another serotype.

    [0049] According to a particular embodiment, the AAV capsid is selected from AAV-1, -2, AAV-2 variants (such as the quadruple-mutant capsid optimized AAV-2 comprising an engineered capsid with Y44+500+730F+T491V changes, disclosed in Ling et al., 2016, -3 and AAV-3 variants (such as the AAV3-ST variant comprising an engineered AAV3 capsid with two amino acid changes, S663V+T492V, disclosed in Vercauteren et al., 2016, -3B and AAV-3B variants, -4, -5, -6 and AAV-6 variants (such as the AAV6 variant comprising the triply mutated AAV6 capsid Y731F/Y705F/T492V form disclosed in Rosario et al., 2016), -7, -8, -9 and AAV-9 variants (such as AAVhu68), - 2G9, -10 such as -cy10 and -rh10, -rh39, -rh43, -rh74, -dj, Anc80, LK03, AAV.PHP, AAV2i8, porcine AAV such as AAVpo4 and AAVpo6, and tyrosine, lysine and serine capsid mutants of AAV serotypes. In addition, the AAV capsid is selected from other non-natural engineered variants (such as AAV-spark100), chimeric AAV or AAV serotypes obtained by shuffling, rationale design, error prone PCR, and machine learning technologies. In a particular embodiment, the Cap gene encodes VP capsid proteins derived from at least two different AAV serotypes, or encodes at least one chimeric VP protein combining VP protein regions or domains derived from at least two AAV serotypes. For example a chimeric AAV capsid can derive from the combination of an AAV8 capsid sequence with a sequence of an AAV serotype different from the AAV8 serotype, such as any of those specifically mentioned above. In another embodiment, the capsid of the AAV vector comprises one or more variant VP capsid proteins such as those described in WO2015013313, in particular the RHM4-1, RHM15-1, RHM15-2, RHM15-3/RHM15-5, RHM15-4 and RHM15-6 capsid variants. In a particular embodiment, the capsid of the AAV vector is a hybrid between AAV serotype 9 (AAV9) and AAV serotype 74 (AAVrh74) capsid proteins. For example, the AAV serotype may be a -rh74-9 serotype as disclosed in WO2019/193119 (such as the Hybrid Cap rh74-9 serotype described in examples of WO2019/193119; a rh74-9 serotype being also referred to herein as "-rh74-9", "AAVrh74-9" or "AAV-rh74-9") or a -9-rh74 serotype as disclosed in WO2019/193119 (such as the Hybrid Cap 9-rh74 serotype described in the examples of WO2019/193119; a -9-rh74 serotype being also referred to herein as "-9-rh74", "AAV9-rh74", "AAV-9-rh74", or "rh74-AAV9"). For example, the capsid of the AAV vector is a peptide-modified hybrid between AAV serotype 9 (AAV9) and AAV serotype 74 (AAVrh74) capsid proteins, as described in PCT/EP2019/076958, such as an AAV9-rh74 hybrid capsid or AAVrh74-9 hybrid capsid modified with the P1 peptide described in the examples of PCT/EP2019/076958For another example, the AAV serotype may be a hybrids AAV2/13 as disclosed in PCT/EP2020/061380.

    [0050] For example, the genome of the pseudotyped vector may have a capsid derived from the AAV8, AAV9, AAVrh74 or AAV2i8 serotype, and its genome may be derived from and different serotype. In a particular embodiment, the AAV vector has a capsid of the AAV8, AAV9 or AAVrh74 serotype, in particular of the AAV8 or AAV9 serotype, more particularly of the AAV8 serotype.

    [0051] In a specific embodiment, wherein the vector is for use in delivering the transgene to muscle cells, the AAV vector may be selected, among others, in the group consisting of AAV8, AAV9 and AAVrh74.

    [0052] In another specific embodiment, wherein the vector is for use in delivering the transgene to liver cells, the AAV vector may be selected, among others, in the group consisting of AAV5, AAV8, AAV9, AAV-LK03, AAV-Anc80 and AAV3B.

    [0053] In another embodiment, the capsid is a modified capsid. In the context of the present invention, a "modified capsid" may be a chimeric capsid or capsid comprising one or more variant VP capsid proteins derived from one or more wild-type AAV VP capsid proteins.

    [0054] In a particular embodiment, the AAV vector is a chimeric vector, i.e. its capsid comprises VP capsid proteins derived from at least two different AAV serotypes, or comprises at least one chimeric VP protein combining VP protein regions or domains derived from at least two AAV serotypes. Examples of such chimeric AAV vectors useful to transduce liver cells are described in [6] and in [7]. For example a chimeric AAV vector can derive from the combination of an AAV8 or AAV9 capsid sequence with a sequence of an AAV serotype different from the AAV8 or AAV9 serotype, such as any of those specifically mentioned above. In another embodiment, the capsid of the AAV vector comprises one or more variant VP capsid proteins such as those described in WO2015013313, in particular the RHM4-1, RHM15-1, RHM15-2, RHM15-3/RHM15-5, RHM15-4 and RHM15-6 capsid variants, which present a high liver tropism.

    [0055] In another embodiment, the modified capsid can be derived also from capsid modifications inserted by error prone PCR and/or peptide insertion (e.g. as described in [8], or in [9]. In addition, capsid variants may include single amino acid changes such as tyrosine mutants (e.g. as described in [10]). Another example is the fusion of Anthopleurin-B to the N-terminus of AAV VP2 capsid protein described in [11].

    [0056] In addition, the genome of the AAV vector may either be a single stranded or self-complementary double-stranded genome [12]. Self-complementary double-stranded AAV vectors are generated by deleting the terminal resolution site (trs) from one of the AAV terminal repeats. These modified vectors, whose replicating genome is half the length of the wild type AAV genome, have the tendency to package DNA dimers.

    [0057] In a preferred embodiment, the AAV vector implemented in the practice of the present invention has a single stranded genome, and further preferably comprises an AAV8, AAV9, AAVrh74 or AAV2i8 capsid, in particular an AAV8, AAV9 or AAVrh74 capsid, such as an AAV8 or AAV9 capsid, more particularly an AAV8 capsid.

    Cell



    [0058] The invention also relates to a cell transformed with the nucleic acid molecule of any one of claims 1 to 5 or the vector of any one of claims 6 to 9.

    [0059] For example, the host cell can be a cell (or cell line) appropriate for production of the vector, e.g. for production of AAV. In some examples, the host cell is a mammalian cell, such as a HEK-293, BHK, Vero, RD, HT-1080, A549, Cos-7, ARPE-19, or MRC-5 cell.

    [0060] The host cell can also be a cell which is the target for a gene therapy, such as a liver cell, a kidney cell or an intestinal cell.

    [0061] In some embodiments, the cell is an isolated cell.

    Composition



    [0062] The invention also relates to a composition comprising the nucleic acid construct of the invention, the vector of the invention, or the cell of the invention. The composition of the invention is preferably a pharmaceutical composition.

    [0063] The composition can take the form of solutions, suspensions, emulsions, tablets, pills, capsules, powders, sustained-release formulations and the like.

    [0064] Such composition will contain a therapeutically effective amount of the nucleic acid construct of the invention, of the vector of the invention, or of the cell of the invention, preferably in purified form, together with a suitable amount of carrier so as to provide the form for proper administration to the subject. In a particular embodiment, the nucleic acid construct, vector or cell of the invention is formulated in a composition comprising phosphate-buffered saline and supplemented with 0.25% human serum albumin. In another particular embodiment, the nucleic acid construct, vector or cell of the invention is formulated in a composition comprising ringer lactate and a non-ionic surfactant, such as pluronic F68 at a final concentration of 0.01-0.0001%, such as at a concentration of 0.001%, by weight of the total composition. The formulation may further comprise serum albumin, in particular human serum albumin, such as human serum albumin at 0.25%. Other appropriate formulations for either storage or administration are known in the art, in particular from WO 2005/118792.

    [0065] In a preferred embodiment, the composition is formulated in accordance with routine procedures as a pharmaceutical composition adapted for intravenous or intrathecal administration to human beings. Typically, compositions for intravenous administration are solutions in sterile isotonic aqueous buffer. Where necessary, the composition may also include a solubilizing agent and a local anesthetic such as lignocaine to, ease pain at the, site of the injection.

    Method of treatment



    [0066] The invention also relates to the nucleic acid construct of the invention, the vector of the invention, the cell of the invention or the composition of the invention, for use as a medicament.

    [0067] The invention also relates to the nucleic acid construct of the invention, the vector of the invention, the cell of the invention or the composition of the invention, for use in the treatment of glycogen storage disease Ia (GSD-Ia).

    [0068] The nucleic acid construct, the vector, the cell or the composition of the invention may be administered to a subject by any effective route. Exemplary routes of administration include, but are not limited to, injection (such as subcutaneous, intramuscular, intradermal, intraperitoneal, intrathecal, and intravenous), oral, intraductal, sublingual, rectal, transdermal, intranasal, vaginal and inhalation routes.

    [0069] The nucleic acid construct, the vector, the cell or the composition of the invention may be administered to a subject in a therapeutically effective amount, i.e. in an amount sufficient to achieve the desired effect in a subject, or in the cell, being treated. The effective amount of the nucleic acid construct, the vector, the cell or the composition of the invention will be dependent on several factors, including, but not limited to the subject or cells being treated, and the manner of administration.

    [0070] The amount of the therapeutic (i.e. a nucleic acid construct, vector or cell) of the invention which will be effective in the treatment of a disease, such as GSD-Ia, can be determined by standard clinical techniques. In addition, in vivo and/or in vitro assays may optionally be employed to help predict optimal dosage ranges. The precise dose to be employed in the composition will also depend on the route of administration, and the seriousness of the disease, and should be decided according to the judgment of the practitioner and each patient's circumstances. The dosage of the nucleic acid, the vector or the cell administered to the subject in need thereof will vary based on several factors including, without limitation, the route of administration, the specific disease treated, the subject's age or the level of expression necessary to require the therapeutic effect. One skilled in the art can readily determine, based on its knowledge in this field, the dosage range required based on these factors and others. In case of a treatment comprising administering a viral vector, such as an AAV vector, to the subject, typical doses of the vector are of at least 1x108 vector genomes per kilogram body weight (vg/kg), such as at least 1x109 vg/kg, at least 1x1010 vg/kg, at least 1x1011 vg/kg, at least 1x1012 vg/kg, at least 1x1013 vg/kg, or at least 1x1014 vg/kg.

    [0071] The therapeutic (i.e. a nucleic acid construct, vector or cell) of the invention can be administered in a single dose, or in multiple doses (such as 2, 3, 4, 5, 6, 7, 8, 9 or 10 doses) as needed for the desired therapeutic results.

    Examples


    Materials and methods



    [0072] We have prepared two nucleic acid constructs (hereafter "transgene expression cassettes") comprising the human G6pc gene encoding G6Pase-a, under the control of different promoters:
    • The alpha-1-anti-trypsin (hAAT) promoter. The nucleic acid sequence of the expression cassette is SEQ ID NO: 11.
    • The endogenous promoter of the human G6pc gene (hGPE). The nucleic acid sequence of the expression cassette is SEQ ID NO: 10.


    [0073] The transgene expression cassettes are represented in Figure 1A.

    [0074] The two transgene expression cassettes were pseudotyped in AAV9 to obtain two different AAV vectors, namely AAV9-hAAT-hG6PC and AAV9-hGPE-hG6PC.

    [0075] The two vectors or PBS (negative control) were independently tested in a liver-specific G6pc knockout mouse model (L.G6pc-/-, [13]), i.e. GSD-Ia mice. As a positive control, WT mice (L.G6pc+/+) were infused with PBS.

    In vivo studies



    [0076] Mice were fed either a standard chow diet (A04 diet, Safe) or a high fat/high sucrose diet (made by INRAE, Jouy en Josas), known to accelerate hepatic tumor development in L.G6pc-/- mice. Proneness to tumor formation was induced in mice by feeding them with a modified chow diet composed of 36% fat (INRA) [14].

    [0077] AAV vectors were administered intravenously via the tail vein of L.G6pc-/- mice. Wild type mice (C57Bl/6J mice, Charles Rivers) were injected with PBS via the tail vein. Glycemia was measured on peripheral blood after a 6-hour fasting using a glucometer (Roche Diagnostic). At sacrifice, livers were harvested and weighed to measure the liver/body weight ratio and snap-frozen for further evaluations.

    [0078] Tumors were evaluated in GSDIa mice at sacrifice by visual inspection. Only tumors larger than 2 mm were considered in the count.

    AAV production



    [0079] HEK293T cells were grown in suspension in 250 mL of serum-free medium. The cells were transfected with 3 plasmids: i) a transgene plasmid, containing AAV2 ITRs flanking an expression cassette ii) the helper plasmid pXX6, containing adenoviral sequences necessary for AAV production, and iii) a plasmid containing AAV Rep and Cap genes, defining the serotype of AAV. Two days after transfection, the cells were lysed to release the AAV particles.

    [0080] The viral lysate was purified by affinity chromatography. Viral genomes were quantified by a TaqMan real-time PCR assay using primers and probes corresponding to the ITRs of the AAV vector genome [17].

    G6Pase enzyme activity measurement



    [0081] G6Pase enzyme activity was measured in homogenates from freeze-clamped livers as already reported in [13]. Briefly, tissues homogenates were incubated with glucose-6-phosphate (Sigma) for fifteen minutes at 37°C. The reaction was stopped by adding trichloroacetic acid and the released phosphate was measured by complexation with ammonium molybdate and citrate arsenite. The resulting absorbance was measured on at 700 nm.

    Measurement of glycogen content



    [0082] Glycogen content was measured indirectly in tissue homogenates as the glucose released after total digestion with Aspergillus Niger amyloglucosidase (Sigma). Samples were incubated for 20 min at 95°C in the presence of 0.3 M NaOH and then cooled at 4°C. Samples were then added with amyloglucosidase and incubated at 37°C for 90 minutes. The glucose released was determined with a commercial glucose assay kit.

    Vector genome copy number (VGCN) quantification



    [0083] For vector genome copy number (VGCN) quantification in samples, DNA was extracted from samples using KingFisher (Thermo Fisher Scientific). Real-time PCR was performed on 1µL of DNA, using the protocol for AAV vectors titration described above. Exon Mex5 of titin gene was used as genomic DNA loading control.

    Example 1 : Correction of the liver phenotype in GSD-Ia mice 15 days after intravenous injection of AAV vectors expressing human G6Pase-a



    [0084] The two AAV9 vectors were independently injected in L.G6pc-/- mice fed a standard diet at the dose of 1x1011 vg/mouse (Figure 1A).

    [0085] Fifteen days after vectors injection, the concentration of glucose in the blood was measured after 6 hours of fasting. Glycaemia was completely normalized in mice injected with the two vectors (Figure 1B).

    [0086] G6PC activity was then measured in liver. The AAV9-hAAT-hG6PC vector achieved supraphysiological activity and showed the highest activity when compared to AAV9-hGPE-hG6PC vector (Figure 1C).

    [0087] Glycogen concentration was also measured. Complete correction of glycogen accumulation and hepatomegaly was obtained with the AAV9-hAAT-hG6PC but not with the vector bearing the hGPE promoter (Figure 1D, E respectively), reflecting the higher G6Pase activity achieved in mice treated with the AAV9 vector bearing hAAT promoter. The similar vector genome copy numbers per diploid genome measured in mice injected with the two AAV vectors (Figure 1F) indicates a similar transduction efficacy in liver.

    Example 2: long-term correction of the liver phenotype in GSD-Ia mice after intravenous injection of AAV vectors expressing human G6Pase-a



    [0088] To assess the long-term efficacy of the two vectors, we performed a 7-months study. Vectors were injected in L.G6pc-/- mice fed a standard diet at a dose of 2.5x1011 vg/mouse (Figure 2A). Seven months after vectors injection, the concentration of glucose in the blood was measured after 6 hours of fasting. Glycemia was corrected in all the animals who received the G6PC-expressing vectors (Figure 2B). Importantly, L.G6pc-/- mice treated with AAV9-hAAT-hG6PC showed supraphysiological liver G6Pase-a activity that was significantly higher of the activity measured in AAV9-hGPE-hG6PC -treated L.G6pc-/- mice (Figure 2C).

    [0089] Glycogen accumulation and hepatomegaly were completely rescued in animals injected with the two vectors (Figure 2D, E). Higher vector genome copy numbers per diploid genome were measured in mice injected with the AAV9-hGPE-hG6PC vector (Figure 2F) possibly reflecting a slightly lower liver transduction achieved with the AAV9-hAAT-hG6PC vector.

    [0090] Taken together, these results indicate that G6Pase-a expression is increased with the hAAT promoter. Thus, hAAT promoter is suitable for AAV gene therapy for GSD-Ia with a potency superior to the hGPE promoter.

    Example 3: hGPE-directed gene therapy promotes hepatic tumor formation in L.G6DC-/- mice fed a high fat/hiah sucrose diet.



    [0091] Adenoma formation is one of the hallmarks of GSD-Ia in humans, reported in most of the affected individuals in the second and third decades of life. In L.G6pc-/- mice, almost all the mice fed a standard diet developed liver adenomas by 18 months of age [13]. This slow process can be accelerated by high fat/high sucrose (HF/HS) diet. Approximately 85 % of L.G6pc-/- mice fed a HF/HS diet developed multiple hepatic tumors at nine months of age [14]. Thus, L.G6pc-/- mice fed with HF/HS diet represent a robust model to evaluate the efficacy and the safety of gene replacement strategies in the prevention of tumors formation in GSDIa.

    [0092] We therefore tested the AAV9-hAAT-hG6PC and the AAV9-hGPE-hG6PC vectors in L.G6pc-/-mice fed a HF/HS diet (Figure 3A). Eight months after treatment, only the vector bearing the hAAT promoter completely rescued glycemia (Figure 3B). Under HF/HS diet, the levels of G6Pase activity in AAV-treated animals were significantly lower than those measured in L.G6pc+/+ animals. Although AAV9-hAAT-hG6PC -treated animals showed higher G6Pase activity levels, statistical significance was not reached when compared to L.G6pc-/- mice treated with AAV9-hGPE-hG6PC vector (Figure 3C). Similar vector genome copies per diploid genome were measured in AAV-treated mice (Figure 3D).

    [0093] Interestingly, necropsy of the mice revealed a higher number of tumors in the livers of mice treated with the hGPE-bearing AAV vectors compared to those that received the AAV9-hAAT-hG6PC (Figure 3E). These results suggest that the use of AAV9-hAAT-hG6PC may decrease the transformation rate of hepatocytes thus resulting in a decreased frequency of adenomas compared to AAV9-hGPE-hG6PC.

    References cited under the form "[reference number]"



    [0094] 
    1. [1] Chandler et al., Vector design influences hepatic genotoxicity after, The Journal of Clinical Investigation, 2015
    2. [2] Mates et al. Nat Genet. 2009 Jun;41(6):753-61. doi: 10.1038/ng.343
    3. [3] Ling et al., 2016 Jul 18, Hum Gene Ther Methods.
    4. [4] Vercauteren et al., 2016, Mol. Ther. Vol. 24(6), p. 1042
    5. [5] Rosario et al., 2016, Mol Ther Methods Clin Dev. 3, p.16026
    6. [6] Shen et al., 2007 Molecular Therapy, volume 15, issue 11, pages 1955-1962
    7. [7] Tenney et al., Virology, volumes 454-455, April 2014, pages 227-236
    8. [8] Bartel et al., Front. Microbiol., 04 October 2011 https://doi.org/10.3389/fmicb.2011.00204
    9. [9] Michelfelder et al. (PLoS ONE, 2009, 4, e5122
    10. [10] Zhong et al., PNAS June 3, 2008 105 (22) 7827-7832; https://doi.org/10.1073/pnas.0802866105
    11. [11] Finet et al., Virology, 2018, 513, 43-51.
    12. [12] McCarty et al., 2003 Gene Therapy Dec;10(26):2112-8.
    13. [13] Mutel et al., Targeted deletion of liver glucose-6 phosphatase mimics glycogen storage disease type 1a including development of multiple adenomas, Journal of Hepatology, 2011 Mar;54(3):529-37. doi: 10.1016/j.jhep.2010.08.014. Epub 2010 Oct 1.
    14. [14] Gjorgjieva M. et al, Dietary exacerbation of metabolic stress leads to accelerated hepatic carcinogenesis in glycogen storage disease type Ia, J. Hepatol. 2018; Nov;69(5): 1074-1087. doi: 10.1016/j.jhep.2018.07.017. Epub 2018 Sep 5.
    15. [15] George L. et al, Hemophilia B Gene Therapy with a High-Specific-Activity Factor IX Variant. N Engl J Med. 2017 Dec 7;377(23):2215-2227. doi: 10.1056/NEJMoa1708538.
    16. [16] Zhang L. et al, An evolutionary approach to optimizing glucose-6-phosphatase-α enzymatic activity for gene therapy of glycogen storage disease type Ia. J Inherit Metab Dis. 2019 May;42(3):470-479. doi: 10.1002/jimd.12069. Epub 2019 Feb 22
    17. [17] Rohr et al., J. Virol. Methods, 2002, 106, 81-88)

    Sequence listing



    [0095] 
    SEQ ID NO :DescriptionSequence
    1 hG6PCwt (amino acid)

     
    2 hG6PCwt (nucleic acid) (Encoding SEQ ID NO : 1)

     
    3 hG6PCco (nucleic acid) (Codon optimized - encoding SEQ ID NO : 1)

     
       

     
    4 hG6PCmut (nucleic acid) (identical to SEQ ID NO: 2 except for a c >g mutation at position 893) (Encoding SEQ ID NO : 12)

     
    5 hG6PCmutco (Nucleic acid) (Codon optimized - encoding SEQ ID NO : 12)

     
    6 hGPE

     
      promoter (4 nucleotides difference to hGPE promoter in NG011808.1)

     
    7 hAAT promoter + ApoE enhancer

     
       

     
    8 hAAT promoter

     
    9 ApoE enhancer

     
    10 hGPE_HBB2_ hG6PCwt_bG H (expression cassette used in the examples having hGPE promoter)

     
       

     
    11 hAAT_HBB2_ hG6PCwt_HB B2 (expression cassette used in the examples having hAAT promoter)

     
       

     
    12 hG6PCmut (amino acid)

     
    13 Modified G6Pase-a (R3K)

     
       

     
    14 Modified G6Pase-a (Q54R)

     
    15 Modified G6Pase-a (Q139R)

     
    16 Modified G6Pase-a (I142K)

     
       

     
    17 Modified G6Pase-a (S196R)

     
    18 Modified G6Pase-a (H199Q)

     
    19 Modified G6Pase-a (Q242R)

     
       

     
    20 Modified G6Pase-a (Q247R)

     
    21 Modified G6Pase-a (L292F)

     
    22 Modified G6Pase-a (S298C)

     
       

     
    23 Modified G6Pase-a (A301V)

     
    24 Modified G6Pase-a (V318T)

     
    25 Modified G6Pase-a (V324T)

     
       

     
    26 Modified G6Pase-a (V332A)

     
    27 Modified G6Pase-a (Q347R)

     
    28 Modified G6Pase-a (L349F)

     
       

     
         
    29 Modified G6Pase-a (R3K)

     
    30 Modified G6Pase-a (Q54R)

     
    31 Modified G6Pase-a (Q139R)

     
    32 Modified G6Pase-a (I142K)

     
    33 Modified G6Pase-a (S196R)

     
       

     
    34 Modified G6Pase-a (H199Q)

     
    35 Modified G6Pase-a (Q242R)

     
    36 Modified G6Pase-a (Q247R)

     
    37 Modified G6Pase-a (L292F)

     
    38 Modified G6Pase-a (S298C)

     
    39 Modified G6Pase-a (A301V)

     
    40 Modified G6Pase-a (V318T)

     
    41 Modified G6Pase-a (V324T)

     
    42 Modified G6Pase-a (V332A)

     
    43 Modified G6Pase-a (Q347R)

     
    44 Modified G6Pase-a (L349F)

     

















































































    Claims

    1. A nucleic acid construct for the expression of a glucose-6-phosphatase-a (G6Pase-a) in a cell, the construct comprising a nucleic acid sequence encoding the G6Pase-a, wherein the nucleic acid sequence encoding the G6Pase-a is operably linked to a human alpha-1 antitrypsin (hAAT) promoter.
     
    2. The nucleic acid construct according to claim 1, wherein the G6Pase-a has an amino acid sequence at least 90% identical to SEQ ID NO: 1.
     
    3. The nucleic acid construct according to any of claims 1 or 2, wherein the nucleic acid sequence encoding the G6Pase-a comprises a nucleotide sequence having at least 90% identity with SEQ ID NO: 2.
     
    4. The nucleic acid construct according to any of claims 1 to 3, wherein the hAAT promoter comprises a nucleotide sequence having at least 90% identity with SEQ ID NO: 8.
     
    5. The nucleic acid construct according to any of claims 1 to 4, wherein said construct comprises a nucleotide sequence having at least 90% identity with SEQ ID NO: 7 or comprises the nucleotide sequence SEQ ID NO: 11.
     
    6. The nucleic acid construct according to any of claims 1 to 5, wherein the cell is a liver cell, a kidney cell or an intestine cell.
     
    7. A vector comprising the nucleic acid construct of any of claims 1 to 6.
     
    8. The vector of claim 7, which is a viral vector, such as lentiviral vector or adeno-associated virus (AAV) vector.
     
    9. The vector of any of claim 7 or 8, which is an AAV vector.
     
    10. The vector of any of claims 7 to 9, which is an AAV serotype 8 (AAV8) vector.
     
    11. A cell transformed with the nucleic acid molecule of any one of claims 1 to 6 or the vector of any one of claims 7 to 10.
     
    12. The cell according to claim 11, which is a liver cell, an intestinal cell or a kidney cell.
     
    13. A composition comprising the nucleic acid construct of any one of claims 1 to 6, the vector of any one of claims 7 to 10, or the cell of any one of claims 11 to 12.
     
    14. The nucleic acid construct of any one of claims 1 to 6, the vector of any one of claims 7 to 10, the cell according to any one of claims 11 to 12 or the composition according to any one of claim 13, for use as a medicament.
     
    15. The nucleic acid construct of any one of claims 1 to 6, the vector of any one of claims 7 to 10, the cell according to any one of claims 11 to 12 or the composition according to any one of claim 13, for use in the treatment of glycogen storage disease Ia (GSD-Ia).
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description




    Non-patent literature cited in the description