The present invention relates to modulators of the unconventional secretory pathway for use in the treatment of Alexander disease.

Alexander disease is a rare, slowly progressing and incurable neurodegenerative disorder that is attributed to mutations in glial fibrillary acidic protein (GFAP), with one of the main symptoms being a demyelination. While it is known that GFAP mutations are detrimental for the development of Alexander disease, the exact pathomechanism is still unknown. Glial fibrillary acidic protein is a type III intermediate filament that contains so-called head, rod and tail domains. Many of the disease-causing mutations are located in the so-called 2A rod domain. An analysis of prevalence of onset for Alexander disease revealed that mutations in the 2A rod region are responsible for most of the severe and early cases with infantile and juvenile onset of Alexander disease.

It has been suggested that the unconventional secretory pathway (USP) might play some role in neurodegenerative disease pathology such as Alzheimer's disease, as proteins associated specifically with neurodegenerative diseases can be secreted by unconventional means. For example the insulin-degrading enzyme (IDE), which is a ubiquitously expressed zinc- metalloprotease that degrades several pathophysiologically significant substrates such as the amyloid β-protein, is a protein that can be secreted into the extracellular space via the unconventional secretory pathway.

UD 40655 / SAM:AL Currently, no cure or accepted course of treatment for Alexander disease is available.

Therefore, the objective underlying the present invention was to provide means being usable in the treatment of Alexander disease.

The problem is solved by a modulator of the unconventional secretory pathway selected from the group comprising 3-hydroxy-3-methylglutaryl-Coenzyme A (HMG-CoA) reductase inhibitors, farnesyl transferase inhibitors, Rho-associated protein kinase inhibitors, geranylgeranyl transferase inhibitors, cells expressing the wild type form of glial fibrillary acidic protein (GFAP) gene and/or viruses comprising the Rabl 1, Rab27a, Rab27b, or Rab35 gene for use in the treatment of Alexander disease.

Surprisingly it was found that modulators of the unconventional secretory pathway are able to reverse the effect of Alexander disease-related mutations in glial fibrillary acidic protein (GFAP) on the secretion of insulin-degrading enzyme (IDE). Beneficially, the modulators according to the invention can be useful in the treatment of Alexander disease. The findings suggest that modulators of the unconventional secretory pathway provide a viable approach to control the unconventional secretion pathway in case of certain Alexander disease-causing GFAP mutations. Hence, the modulators of the unconventional secretory pathway can be used to alleviate the symptoms and prolong the life expectancy.

It is thought that the advantageous effects are derived due to an interaction between glial fibrillary acidic protein and the insulin-degrading enzyme. This interaction was shown to be affected by Alexander disease-related mutations in the 2 A rod region of GFAP. These clinically relevant GFAP mutations by affecting the association between insulin-degrading enzyme (IDE) and GFAP thereby impair the unconventional secretory pathway in Alexander disease patients. Using the insulin-degrading enzyme as a marker for the unconventional secretory pathway, it could be shown that Alexander disease-related mutations in the 2A rod region of GFAP lead to a significant reduction in the secretion of insulin-degrading enzyme. This influence of Alexander disease-related mutations of GFAP can be reversed by the modulators of the unconventional secretory pathway, as the treatment of cells expressing the Alexander disease-related mutated variant of GFAP significantly improved the secretion of insulin-degrading enzyme (IDE).

Preferred modulators of the unconventional secretory pathway for use in the treatment of Alexander disease are HMG-CoA reductase inhibitors. As used herein, the term "HMG-CoA reductase inhibitor" refers to a compound that targets and inhibits the activity of the 3- hydroxy-3-methylglutaryl-Coenzyme A (HMG-CoA) reductase. HMG-CoA reductase is an enzyme of the mevalonate pathway, which provides cholesterol and other isoprenoids. In a preferred embodiment, the HMG-CoA reductase inhibitor is a statin. Preferred statins are selected from the group comprising lovastatin (INN), atorvastatin (INN), fluvastatin (INN), pravastatin (INN), pravastatin (INN), rosuvastatin (INN) and/or simvastatin (INN). A most preferred statin is lovastatin. Lovastatin is the International Nonproprietary Name (INN) of a statin denoted [(lS,3R,7S,8S,8aR)-8-[2-[(2R,4R)-4-hydroxy-6-oxooxan-2-yl]et hyl]-3,7- dimethyl-l,2,3,7,8,8a-hexahydronaphthalen-l-yl] (2S)-2-methylbutanoate according to the IUPAC nomenclature. It could be shown that lovastatin can rescue the effect of the Alexander disease-causing mutation on the secretion of endogenous insulin-degrading enzyme (IDE). IDE was used as a marker for the levels of exosomes, and indicated that GFAP mutations affect exosome release from astrocytes.

It could further be shown that a treatment with simvastatin improved the neurological phenotypes in AxD model mice in vivo as well as successfully reduced the accumulation of the USP marker protein Alix in brain lysates, which is indicative of a reduction in USP release. These findings indicate that statin modulators provide a particularly advantageous therapeutic option for use in the treatment of Alexander disease patients. A further preferred statin is fluvastatin. The statins atorvastatin (INN), fluvastatin (INN), pitavastatin (INN), pravastatin (INN), rosuvastatin (INN) and simvastatin (INN) are denoted:

- (3i?,5i?)-7-[2-(4-fluorophenyl)-3-phenyl-4-(phenylcarbamoyl) -5-propan-2-ylpyrrol- 1 -yl]- 3,5-dihydroxyheptanoic acid,

- (3i?,55 ^, ,6E)-7-[3-(4-fluorophenyl)-l-(propan-2-yl)-lH-indol-2- yl]-3,5-dihydroxyhept-6- enoic acid,

- (3i?,55 ^, ,6E)-7-[2-cyclopropyl-4-(4-fluorophenyl)quinolin-3-yl] -3,5-dihydroxyhept-6-enoic acid,

- (3i?,5i?)-3,5-dihydroxy-7-((li?,2 _l S,6 _l S,8i?,8ai?)-6-hydroxy-2-methyl-8-{[(25)-2- methylbutanoyl]oxy} - 1 ,2,6,7,8,8a-hexahydronaphthalen- 1 -yl)-heptanoic acid,

- (3i?,55 ^, ,6E)-7-[4-(4-fluorophenyl)-2-(N-methylmethanesulfonami do)-6-(propan-2- yl)pyrimidin-5-yl]-3,5-dihydroxyhept-6-enoic acid, and

- (l _l S,3i?,7 _l S,8 _l S,8ai?)-8-{2-[(2i?,4i?)-4-hydroxy-6-oxotetrahydro-2H-p yran-2-yl]ethyl}-3,7- dimethyl- 1 ,2,3,7,8,8a-hexahydronaphthalen- 1 -yl 2,2-dimethylbutanoate,

respectively, according to the IUPAC nomenclature.

Further modulators of the unconventional secretory pathway for use in the treatment of Alexander disease are farnesyl transferase inhibitors. As used herein, the term "farnesyl transferase inhibitor" refers to a class of drugs that target and inhibit the activity of a protein denoted farnesyl-transferase. This enzyme adds a fatty acid molecule to proteins such as the Ras protein. Farnesyl transferase inhibitors can be selected from the group comprising compounds tipifarnib (INN), lonafarnib (INN), and experimental substances BMS-214662, L778123, FTI-277, and L744832.

Tipifarnib (INN) and lonafarnib (INN) are denoted 6-[amino(4-chlorophenyl)(l-methyl-lH- imidazol-5-yl)methyl]-4-(3-chlorophenyl)-l-methylquinolin-2( lH)-one and 4-(2-(4-(8- Chloro-3 , 10-dibromo-6, 11 -dihydro-5H-benzo(5,6)cyclohepta( 1 ,2-b)pyridin- 11 -yl)- 1 - piperidinyl)-2-oxoethyl)-l-piperidinecarboxamide, respectively, according to the IUPAC nomenclature.

The compounds BMS-214662, L778123, FTI-277, and L744832 are denoted:

- (R)-l-((lH-imidazol-5-yl)methyl)-3-benzyl-4-(thiophen-2-ylsu lfonyl)-2,3,4,5-tetrahydro- 1 H-benzo [e] [ 1 ,4]diazepine-7-carbonitrile,

- Benzonitrile,4-[[5-[[4-(3-chlorophenyl)-3-oxo-l-piperazinyl] methyl]-lH-imidazol-l- yl]methyl]-,monohydrochloride (9CI);4-((5-((4-(3-Chlorophenyl)-3-oxo-l- piperazinyl)methyl)- 1 H-imidazo 1- 1 -yl)methyl)benzonitrile hydrochloride,

- L-Methionine,N-[[5-[[(2R)-2-amino-3-mercaptopropyl]amino][ 1 , 1 '-biphenyl]-2- yl]carbonyl]-,methyl ester, and

- propan-2-yl(2S)-2-[[(2S)-2-[(2S,3R)-2-[[(2R)-2-amino-3-sulfa nylpropyl]amino]-3- methylpentoxy] -3 -phenylpropanoyl] amino] -4-methylsulfonylbutanoate,

respectively, according to the IUPAC nomenclature.

Further preferred modulators of the unconventional secretory pathway for use in the treatment of Alexander disease are Rho-associated protein kinase (ROCK) inhibitors. As used herein, the term "Rho-associated protein kinase inhibitor" refers to a class of drugs that target and inhibit the activity of a protein denoted Rho-associated protein kinase (ROCK). Rho- associated protein kinase (ROCK) is a serine/threonine kinase. Two ROCK isoforms ROCKl and ROCK2 have been discovered as being effectors of the small GTPase RhoA. ROCKs have an amino -terminal kinase domain, a mid coiled-coil- forming region containing a Rho- binding domain, and carboxy-terminal cysteine-rich domain. In an embodiment, the Rho-associated protein kinase (ROCK) inhibitors are selected from the group comprising:

( 1 R,4r)-4-((R)- 1 -aminoethyl)-N-(pyridin-4-yl)cyclohexanecarboxamide dihydrochloride (Y-27632), N-[3-[[2-(4-Amino- 1 ,2, 5-oxadiazol-3— yl)-l -ethyl- 1H- imidazo[4,5-c]pyridin-6- yl]oxy]phe-nyl]-4-[2-(4-morpholinyl)ethoxy]benzamide (GSK 269962),

4-[4-(Trifluoromethyl)phenyl]-N-(6~Fluoro-lH-indazol-5-yl)-2 -methyl-6-oxo-l ,4,5,6- tet-rahydro-3-pyridinecarboxamide (GSK 429286),

- (iS)-(+)-2-Methyl- 1 -[(4-methyl-5-iso-quinolinyl)sulfonyl]-hexahydro- 1H- 1 ,4-diazepine (Η 1 152),

(5)-(+)-4-Glycyl-2-methyl- 1 -[(4-met-hyl-5-isoquinolinyl)sulfonyl]-hexahydro- 1H- 1 ,4- diazepine (Glycyl-H 1 152),

1 -[(1 ,2-Dihydro- 1 -oxo-5-isoquinolin-yl)sulfonyl]hexahydro- 1H- 1 ,4-diazepine

hydrochloride (ΗΑ 1 100),

(35)- 1 -[[2-(4-Amino- 1 ,2,5-oxadiazol~3-yl)- 1 -ethyl- lH-imidazo[4,5-c]pyridin-7- yl]carbo-nyl]-3-pyrrolidinamine (SB 772077B),

N- [2- [2-(Dimethylamino)ethoxy] -4-( 1 -H-pyrazo l-4-yl)phenyl-2,3 -dihydro- 1 ,4- benzodioxin~2-carboxamide (SR 3677), and/or

- fasudil.

Y-27632 is a ROCK inhibitor available as a dihydrochloride denoted (lR,4r)-4-((R)-l- aminoethyl)-N-(pyridin-4-yl)cyclohexanecarboxamide dihydrochloride or (+)-(R)-trans-4-(l- aminoethyl)-N-(4-pyridyl)cyclohexanecarboxamide dihydrochloride according to the IUPAC nomenclature.

It could be shown that also a treatment with the Rho-associated protein kinase (ROCK) inhibitor Y-27632 improved the neurological phenotypes in AxD model mice in vivo as well as successfully reduced the accumulation of the USP marker protein Alix in brain lysates. These findings indicate that also Rho-associated protein kinase (ROCK) inhibitors, particularly Y-27632, as modulators provide an advantageous therapeutic option for use in the treatment of Alexander disease patients. Fasudil is the International Nonproprietary Name (INN) of a selective RhoA/Rho kinase (ROCK) inhibitor denoted 5-(l,4-diazepane-l-sulfonyl)isoquinoline according to the IUPAC nomenclature. The further ROCK inhibitors usually are denoted GSK 269962, GSK 429286, H 1152, Glycyl-H 1152, HA 1100, SB 772077B, and SR 3677.

Further modulators of the unconventional secretory pathway for use in the treatment of Alexander disease are geranylgeranyl transferase inhibitors. As used herein, the term

"geranylgeranyl transferase inhibitor" refers to a class of drugs that target and inhibit the activity of a protein denoted geranylgeranyl transferase. Geranylgeranyl transferase postranslationally modifies proteins by adding a prenyl group, an isoprenoid lipid, to the carboxyl terminus of the target protein. Geranylgeranyltransferase inhibitors can be selected from the group comprising GGTI 297 and/or GGTI 298. GGTI 297 is the experimental name of a compound denoted N-[4-[2(i?)-Amino-3-mercaptopropyl]amino-2-(l- naphthalenyl)benzoyl]-L-leucine trifluoroacetate salt. GGTI 297 inhibits RhoA prenylation leading to an inactivation of RhoA/ROCK. GGTI 298 is the experimental name of a compound denoted N-[4-[2(i?)-Amino-3-mercaptopropyl]amino-2-(l-naphthalenyl)b enzoyl]- L-leucine methyl ester trifluoroacetate salt. GGTI 298 inhibits the processing of

geranylgeranylated RaplA. Further preferred modulators of the unconventional secretory pathway for use in the treatment of Alexander disease are cells expressing the wild type form of GFAP gene and/or viruses comprising the Rabl 1, Rab27a, Rab27b, or Rab35 gene.

Also cell-based approaches can provide a viable approach in the treatment of Alexander disease. Cells having undisturbed unconventional secretory pathway (USP) can replace or rescue patient faulty USP. Particularly, a Rab-containing virus or cells overexpressing the wild type form of GFAP gene are usable in therapy. Viral gene therapy most frequently uses non-replicating viruses to deliver therapeutic genes to cells with genetic malfunctions. Particularly the Ras-related protein Rab-35 and Rabl 1, Rab27a/b are usable, as for example those proteins are involved in the regulation of exosome secretion. Preferred is Rab-35.

A further aspect of the present invention relates to a pharmaceutical composition comprising as an active ingredient a modulator of the unconventional secretory pathway selected from the group comprising 3-hydroxy-3-methylglutaryl-Coenzyme A (HMG-CoA) reductase inhibitors, farnesyl transferase inhibitors, Rho-associated protein kinase inhibitors, geranylgeranyl transferase inhibitors, cells expressing the wild type form of glial fibrillary acidic protein (GFAP) gene and/or viruses comprising the Rabl 1, Rab27a, Rab27b, or Rab35 gene for use in the treatment of Alexander disease.

Preferred modulators of the unconventional secretory pathway are HMG-CoA reductase inhibitors. In a preferred embodiment, the pharmaceutical composition comprises as a HMG- CoA reductase inhibitor a statin. Preferred statins are selected from the group comprising lovastatin (INN), atorvastatin (INN), fluvastatin (INN), pitavastatin (INN), pravastatin (INN), rosuvastatin (INN) and/or simvastatin (INN). A most preferred statin is lovastatin. Further preferred statins are selected from the group comprising fluvastatin and/or simvastatin.

Further preferred modulators of the unconventional secretory pathway are Rho-associated protein kinase (ROCK) inhibitors. In an embodiment of the pharmaceutical composition, the Rho-associated protein kinase (ROCK) inhibitors are selected from the group comprising Y- 27632, GSK 269962, GSK 429286, H 1152, Glycyl-H 1152, HA 1100, SB 772077B, SR 3677 and/or fasudil. A preferred Rho-associated protein kinase (ROCK) inhibitor is Y-27632. Further modulators of the unconventional secretory pathway for use in the pharmaceutical composition are farnesyl transferase inhibitors and geranylgeranyl transferase inhibitors. Farnesyl transferase inhibitors can be selected from the group comprising compounds tipifarnib (INN), lonafarnib (INN), and experimental substances BMS-214662, L-778,123, FTI-277 and/or L-744,832. Geranylgeranyl transferase inhibitors can be selected from the group comprising GGTI 297 and/or GGTI 298.

Further preferred modulators of the unconventional secretory pathway for use in the pharmaceutical composition are cells expressing the wild type form of GFAP gene and/or viruses comprising the Rabl 1, Rab27a, Rab27b, or Rab35 gene.

The pharmaceutical composition can comprise a modulator of the unconventional secretory pathway according to the invention as an active ingredient, a pharmaceutically acceptable carrier and optionally other therapeutic ingredients or adjuvants. The present invention hence also relates to a pharmaceutical composition wherein the composition comprises as an active ingredient a modulator of the unconventional secretory pathway according to the invention, and a pharmaceutically acceptable carrier for use in the treatment of Alexander disease. The pharmaceutical carrier can be, for example, a solid, liquid, or gas. Suitable carriers and adjuvants can be solid or liquid and correspond to the substances ordinarily employed in formulation technology for pharmaceutical formulations. For example, water, glycols, oils, alcohols and the like may be used to form liquid preparations such as solutions. Examples of solid carriers include lactose, terra alba, sucrose, talc, gelatin, agar, pectin, acacia, magnesium stearate, and stearic acid. Examples of liquid carriers are sugar syrup, peanut oil, olive oil, and water. Examples of gaseous carriers include carbon dioxide and nitrogen. The compositions can be suitable for oral, dermal, rectal, topical, and parenteral administration. Parenteral administration includes subcutaneous, intramuscular, and intravenous administration, and particularly includes intracranial injections and cerebral shunts.

Compositions suitable for parenteral administration may be prepared as solutions or suspensions in water. Compositions suitable for injectable use include sterile aqueous solutions or dispersions. The pharmaceutical compositions may be conveniently presented in unit dosage form and prepared by any of the methods well known in the art of pharmacy. The pharmaceutical composition may be produced under sterile conditions using standard pharmaceutical techniques well known to those skilled in the art. The present invention also relates to the use of a modulator of the unconventional secretory pathway selected from the group comprising 3-hydroxy-3-methylglutaryl-Coenzyme A (HMG-CoA) reductase inhibitors, farnesyl transferase inhibitors, Rho-associated protein kinase inhibitors, geranylgeranyl transferase inhibitors, cells expressing the wild type form of glial fibrillary acidic protein (GFAP) gene and/or viruses comprising the Rabl 1, Rab27a, Rab27b, or Rab35 gene for the manufacture of a medicament for the treatment of Alexander disease.

Preferably usable modulators of the unconventional secretory pathway are HMG-CoA reductase inhibitors. In a preferred embodiment, the usable HMG-CoA reductase inhibitor is a statin. Preferred statins are selected from the group comprising lovastatin (INN), atorvastatin (INN), fluvastatin (INN), pitavastatin (INN), pravastatin (INN), rosuvastatin (INN) and/or simvastatin (INN). A most preferred statin is lovastatin. Further preferred statins are selected from the group comprising fluvastatin and/or simvastatin. Further preferably usable modulators of the unconventional secretory pathway are Rho- associated protein kinase (ROCK) inhibitors. In an embodiment, the usable Rho-associated protein kinase (ROCK) inhibitors are selected from the group comprising Y-27632, GSK 269962, GSK 429286, H 1152, Glycyl-H 1152, HA 1100, SB 772077B, SR 3677 and/or fasudil. A preferred Rho-associated protein kinase (ROCK) inhibitor is Y-27632.

Further usable modulators of the unconventional secretory pathway for use in the

pharmaceutical composition are farnesyl transferase inhibitors and geranylgeranyl transferase inhibitors. Farnesyl transferase inhibitors can be selected from the group comprising compounds tipifarnib (INN), lonafarnib (INN), and experimental substances BMS-214662, L- 778,123, FTI-277 and/or L-744,832. Geranylgeranyl transferase inhibitors can be selected from the group comprising GGTI 297 and/or GGTI 298. Further preferably usable modulators of the unconventional secretory pathway for use in the pharmaceutical composition are cells expressing the wild type form of GFAP gene and/or viruses comprising the Rabl 1, Rab27a, Rab27b, or Rab35 gene.

A further aspect of the present invention relates to a method of treating Alexander disease, the method comprising administering to a subject a therapeutically effective amount of a modulator of the unconventional secretory pathway selected from the group comprising 3- hydroxy-3-methylglutaryl-Coenzyme A (HMG-CoA) reductase inhibitors, farnesyl transferase inhibitors, Rho-associated protein kinase inhibitors, geranylgeranyl transferase inhibitors, cells expressing the wild type form of glial fibrillary acidic protein (GFAP) gene and/or viruses comprising the Rabl 1, Rab27a, Rab27b, or Rab35 gene.

The term "therapeutically effective amount" is used herein to mean an amount or dose sufficient to cause an improvement in a clinically significant condition in the subject. In embodiments the method of treating Alexander disease refers to administering HMG-CoA reductase inhibitors, particularly a statin. Preferred statins are selected from the group comprising lovastatin (INN), atorvastatin (INN), fluvastatin (INN), pitavastatin (INN), pravastatin (INN), rosuvastatin (INN) and/or simvastatin (INN). A most preferred statin is lovastatin. Further preferred statins are selected from the group comprising fluvastatin and/or simvastatin.

In another embodiment, the method of treating Alexander disease refers to administering Rho-associated protein kinase (ROCK) inhibitors selected from the group comprising Y- 27632, GSK 269962, GSK 429286, H 1152, Glycyl-H 1152, HA 1100, SB 772077B, SR 3677 and/or fasudil. A preferred Rho-associated protein kinase (ROCK) inhibitor is Y-27632. Further modulators of the unconventional secretory pathway for use in the method of treating Alexander disease are farnesyl transferase inhibitors and geranylgeranyl transferase inhibitors. Farnesyl transferase inhibitors can be selected from the group comprising compounds tipifarnib (INN), lonafarnib (INN), and experimental substances BMS-214662, L-778,123, FTI-277 and/or L-744,832. Geranylgeranyl transferase inhibitors can be selected from the group comprising GGTI 297 and/or GGTI 298. Further modulators of the unconventional secretory pathway for use in the method of treating Alexander disease are cells expressing the wild type form of GFAP gene and/or viruses comprising the Rabl 1, Rab27a, Rab27b, or Rab35 gene.

Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

The Examples which follow serve to illustrate the invention in more detail but do not constitute a limitation thereof. The figures show:

Figure 1 The schematic representation of the GFAP organisation with the indicated

mutations, which are responsible for the development of Alexander disease.

Figure 2 The effect of Alexander disease causing mutations of GFAP on the secretion of

IDE in COS-7 cells. Figure 2A shows a Western immunoblot analysis of IDE detected in the cell lysates and conditioned media after transfection of the cells with GFAP wild type (GFAP-WT), the Alexander disease causing mutations GFAP-AEx4 and GFAP-I/D/F. Figure 2B shows the respective quantification of IDE secretion given as the ratio of IDE in the medium to IDE in the lysates. Figure 3 The quantification of IDE secretion given as the ratio of IDE in the medium to IDE in the lysates after Western immunoblot analysis of IDE detected in the cell lysates and conditioned media after transfection of COS-7 cells with GFAP wild type (GFAP-WT), Alexander disease-causing GFAP mutation (GFAP-AEx4), and the effect of lovastatin (GFAP-AEx4 + statin).

Figure 4 The quantification of IDE secretion given as the ratio of IDE in the medium to

IDE in the lysates of cells transfected with Alexander disease causing mutations GFAP-AEx4 or GFAP-I/D/F, and of probes of GFAP-AEx4 or GFAP-I/D/F transfected cells, to which were added cells transfected with GFAP wild type (GFAP-AEx4 + GFAP-wt) and (GFAP-I/D/F + GFAP-wt).

Figure 5 The effect of administration of Simvastatin and Y-27632 in AxD mice model in vivo. Figure 5 A shows the grooming attempts of GFAP knock-out mice (GFAP KO) compared to wild type mice (Wt). Figure 5B shows the grooming attempts of wild type mice (Wt), Alexander disease model mice (AxD) treated with the modulators Simvastatin (comp. 1) and Y-27632 (comp. 2), respectively. Figure 5C shows the paw clasping attempts in 1 minute of wild type mice (Wt) and Alexander disease model mice (AxD) treated with the modulators Simvastatin (comp. 1) and Y-27632 (comp. 2), respectively. Figure 5D shows the level of Alix protein (marker of exosome release) for the wild type mice and Alexander disease model mice (AxD) treated with the modulators Simvastatin (comp. 1) and Y-

27632 (comp. 2), respectively. Data are given as mean ± standard deviation (n=5). Figure 6 The results of 6 months treatment of patient with type II Alexander disease with

Simvastatin (two months, 33 mg) followed by Fluvastatin (four months, 10 mg). Figure 6 A shows the protein levels of GFAP and Alix protein in CSF samples collected before and after seven months of the therapy. Figure 6B shows the total

SWAL-QOL score before and during the therapy. Overall improvement was observed after 3 months of the treatment. Figure 6C shows the subset of SWAL- QOL score reflecting physical symptoms related to swallowing deficit.

Improvement was observed after 3 months of the treatment.

Examples

Materials and Methods:

Cell Lines and Cell Culture

COS-7 cells, a fibroblast-like cell line from monkey kidney tissue (ATCC, USA), were cultured in Dulbecco's Modified Eagle Medium (DMEM) (Life Technologies) containing 10% Fetal calf serum (FCS) (Life Technologies) and 1% Penicillin/Streptomycin (PS) (Life Technologies) (DMEM +/+) and splitted into new dishes (Corning). For all experiments cells were counted by using a Neubauer counting chamber. To estimate cell number (cells/ml), the average number from four big squares of the Neubauer chamber was multiplied by 10Ό00 and the cell suspension was diluted to the desired cell concentration.

Primary cultures of astrocytes were obtained from El 8 mouse embryos by brief trypsinzation of meninges-free brains with subsequent mechanical separation. Cell suspension was seeded in T-75 flasks and grown in DMEM containing 10% FCS with 1% PS for at least 14 days. Transient transfection of COS-7 cells

COS-7 were seeded on coverslips 24 hours before the transfection procedure. Transfection was done using Lipofectamine 2000 (Life Technologies) and according to the manufacturer guidelines. After 48 hours cells were fixed and subjected to immunofluorescent labeling procedure as described below.

Immunocytochemistry

Cells were fixed with 4% paraformaldehyde (PFA), washed, permeabilized in 0.25% TritonX- 100 (Roth) in phosphate buffered saline (PBS, 140 mM NaCl, 10 mM NaH ₂ P0 ₄ , 1.75 mM KH ₂ PO ₄ , 2.5 mM KC1, pH 7.4), and blocked in 10% Bovine serum albumin (BSA, Roth) in PBS for 1 hour. The cells were then incubated with the appropriate primary antibodies IDE (rb) (1 :300, Abeam), or GFAP (1 :300, Cell Cignallmg), for 1 hour in 5% BSA/PBS, washed, and then incubated in secondary antibodies for 1 hour (AlexaFluor 488, 546, 647 (Life Technologies), and Phalloidin:TRITC (1 mg/ml) (Sigma)) in 3% BSA/PBS.

Protein extraction and Western immunobloting

Cells were washed with PBS, resuspended in 800 μΐ lysis buffer (150 mM NaCl, 10 mM Tris pH 7.5, 1% Igepal, 5 mM EDTA), homogenized using a syringe with 23G needle and centrifuged at 13,200 rpm for 15 min at 4°C. The supernatant was boiled with loading buffer (5x SDS-Loading buffer: 250 mM TrisHCl pH 6.8, 30% Glycerin, 10% SDS, 5% β- mercaptoethanol, 0.02% Bromphenol blue).

Proteins were separated with SDS-PAGE (10-20%) SDS polyacrylamide gels, Invitrogen). After SDS-PAGE separation proteins were transferred onto nitrocellulose membranes (Whatman Protran) by blotting at 180 V for 2 h and detected with the indicated primary antibodies and HRP conjugated secondary antibodies by enhanced chemiluminescence reagent (GE Healthcare). Signals were quantified with an ECL imager (Biorad) and

QuantityOne software. Secretion assay

COS-7 cells transfected with pcDNA or GFAP variants were seeded on 6 well plates and 48 hours after transfection were washed with DMEM and 800 μΐ of fresh serum free DMEM was added. 12 to 16 hours later the conditioned medium was collected into 1.5 ml tubes and potential cell debris were removed by centrifugation at 1500 rcf for 10 minutes at 4°C. The remaining cells were harvested from dishes and corresponding lysates and samples of conditioned medium were prepared as described above.

Imaging Cell images were obtained on a Zeiss Axiovert 200M microscope equipped with a Apotome 2 and a CCD camera using a PlanApo 63x (1.40 N.A.) oil-immersion objective. For Apotome 2 aquired images four image avaregaing per z-plane was used. Images were captured and analyzed using Axio Vision v4.8.2.0, Image J and Photoshop CS4 Extended software.

Statistics

Statistical tests were performed using the student ^' s t-test. Data are means ± SD, n= 2 independent treatments. P values less than 0.05 were considered as significant; whereas P > 0.05 means data are not significantly different.

Example 1 : Association of endogenous GFAP and IDE in primary astrocytes

The association of glial fibrillary acidic protein (GFAP) and endogenous insulin-degrading enzyme (IDE) was determined in primary astrocytes. Primary mouse astrocytes were obtained from El 8 mouse embryos and after cultivation immunocytochemically stained for

endogenous IDE and GFAP using IDE (1 :300, Abeam) and GFAP (1 :300, Cell Cignallmg) specific antibodies.

Immunofluorescence microscopy of the primary mouse astrocytes showed a detection of endogenous IDE and GFAP, wherein IDE was mainly distributed as punctate structures in the cytosol whereas GFAP appeared as filamentous structures. A double staining for IDE and GFAP revealed an association of both proteins, as both proteins were detectable in the cytosol and IDE was associated with the GFAP filaments. These data show that the glial fibrillary acidic protein (GFAP) associates with endogenous insulin-degrading enzyme (IDE) in primary mouse astrocytes.

Example 2: Association of endogenous GFAP and IDE in COS-7 cells To analyze whether association exists in further cells, COS-7 cells were used for transiently co-transfection of a generated IDE construct comprising the 1,019 amino acids of the mouse wild type and a C-terminal C-myc tag (IDE-WT-Myc) and a generated human wild type GFAP construct (GFAP-WT) comprising the complete head, rod and tail structure of 432 amino acids as shown in Figure 1.

48 hours after the transfection the cells were subjected to immunostaining with IDE (1 :300, Abeam) and GFAP (1 :300, Cell Cignalling) specific antibodies. For control, F-actin was visualized with Phalloidin:TRITC. Immunofluorescence microscopy of the primary mouse astrocytes showed that overexpressed GFAP formed an extensive intermediate filament network in the COS-7 cells that was similar to the GFAP expression pattern observed in the primary astrocytes in Example 1. Again, IDE was mainly distributed as punctate structures in the cytosol. A double staining for IDE and GFAP showed an association between IDE and GFAP in the full specter of filament assemblies found in COS-7 cells, from the thick bundles to the fine filaments.

These results suggest that IDE associates with GFAP in COS-7 cells in a similar manner as in primary mouse astrocytes.

Example 3 : Effect of mutations in the 2A rod domain in GFAP on the association with IDE

COS-7 cells were used for analysis of the protein-protein interaction of the GFAP constructs having the mutation causing Alexander disease and IDE. GFAP constructs having a mutation in the 2A rod domain causing Alexander disease (AxD) were generated and analysed for the association with IDE. The first GFAP construct had a C→G exchange 3 bp downstream of exon 4 (GFAP-AEx4). This mutation affects the transcription and the product was shorter because of the missing exon 4 (Flint et al., Hum Mutat 33: 1141-1148, 2012). The second GFAP construct had an 8 bp deletion accompanied by a 3 bp insertion (1292 to 1299 bp). Such double mutation results in a frameshift at the C-terminus of GFAP(GFAP-I/D/F).

Thereby the second mutation produced an elongated GFAP with additional 11 amino acids. The COS-7 cells were co transfected with a combination of IDE-WT-Myc and GFAP-AEx4 or of IDE-WT-Myc and GFAP-I/D/F as described above and after 48 hours of overexpression detected with Myc and GFAP specific antibodies.

Immunofluorescence microscopy of the COS-7 cells transiently co -transfected with IDE-WT- Myc and GFAP-AEx4 showed that the expression of the GFAP-AEx4 variant produced small dense spike-like structures. Also, no association between the GFAP-AEx4 variant and IDE was observed. This finding suggests that exon 4 of the glial fibrillary acidic protein (GFAP) contains a motif that is responsible for IDE and GFAP association.

Immunofluorescence microscopy of the COS-7 cells transiently co -transfected with IDE-WT- Myc and GFAP-I/D/F showed that the overexpression of the second mutated variant GFAP- I/D/F resulted in a formation of dense fibers of GFAP located mainly in the perinuclear region, with high IDE association. Since in GFAP-I/D/F variant potential association motif for IDE is unaffected, it can be suggested that wrong GFAP polymerization affected

IDE/GFAP association.

In summary, these findings show that mutations in glial fibrillary acidic protein (GFAP) have an effect on the association with endogenous insulin-degrading enzyme (IDE).

Example 4: Determination of the effect of Alexander disease-causing variants of GFAP on IDE release

To test whether the release of insulin-degrading enzyme (IDE) containing exosomes is affected by Alexander disease (AxD) causing variants of GFAP, COS-7 cells were transfected with GFAP-WT, GFAP-AEx4, and GFAP-I/D/F as described in Example 3. A secretion assay was carried out as described above. As a control pcDNA3.0 vector (Life Technologies) was used. The cells were transfected with the GFAP variants and incubated for 16 hours in DMEM+/+ and in additional step for 8 h in DMEM-/-. IDE was then detected in the cell lysates and conditioned media by Western immunoblotting. A quantification of the IDE secretion was done by ECL imaging.

The figure 2 A shows the Western immunoblot analysis of IDE detected in the cell lysates and the conditioned media after the transfection. The figure 2B shows the quantification of the IDE secretion given as the ratio of IDE in the medium to IDE in the lysates. It can be taken from figure 2 that the overexpression of the GFAP-WT resulted in a stronger release of IDE, as the secretion increased in cells transfected with GFAP-WT in comparison to cells transfected with the control pcDNA 3.0. Both mutations strongly affected the efficiency of the IDE secretion. It can be taken from figure 2B that the mutations in GFAP disrupt the secretion of IDE.

From the results of the secretion assay experiment it can be concluded that GFAP modulates the release of IDE from COS-7 cells. Example 5: Effect of lovastatin on Alexander disease-affected secretion of IDE

The effect of statins on the secretion of IDE disturbed by Alexander disease-causing mutation in the 2A rod region of GFAP was determined by cell transfection and pharmacological treatment in COS-7 cells.

Cells were seeded in 6 well plates day before the transfection to a 50% confluence in DMEM medium supplemented with 10% FCS/1% PS. Next day GFAP variants were transfected using Lipofectamine (Life Technologys) according to the manufacturer's instructions. The COS-7 cells were transfected with GFAP wild type (GFAP-WT) and the Alexander disease causing mutation in the 2A rod region of GFAP (GFAP-AEx4) as described in Example 3. As a control pcDNA3.0 vector (Life Technologies) was used. 36 hours post transfection, the cells were treated either with DMSO (vehicle) or 5 μΜ lovastatin (Sigma Aldrich) for 15 hours. Conditioned media were collected and centrifuged (lOOOx g, 10 min, 4°C). Cells were lysed in ice-cold RIPA lysis buffer (pH 7.5). Proteins were separated by sodium dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE), transferred to nitrocellulose membranes (Whatman), and detected by Western immunoblotting using enhanced chemiluminescence detection (ChemiDoc XRS, Bio-Rad). Signals were quantified with Quantity One Software (Bio-Rad).

The Figure 3 shows the quantification of IDE secretion given as the ratio of IDE in the medium to IDE in the lysates after Western immunoblot analysis of IDE detected in the cell lysates and conditioned media after transfection of the cells with GFAP wild type (GFAP- WT), the Alexander disease causing mutation in the 2A rod region of GFAP (GFAP-AEx4) and GFAP-AEx4 and lovastatin (GFAP-AEx4 + statin). It can be taken from figure 3 that while the Alexander disease causing GFAP mutation GFAP-AEx4 decreased the unconvential secretion of the IDE-positive exosomes in comparison to GFAP wt, the addition of lovastatin strongly improved the affected secretion, almost to a 100% increase compared to GFAP-

These results show that statins can rescue the effect of the Alexander disease-causing mutation on the secretion of endogenous insulin-degrading enzyme (IDE). Example 6: Effect of cell-based therapy on Alexander disease-affected secretion of IDE The effect of cells expressing the wild type variant of GFAP on the unconventional secretion disturbed by Alexander disease-related mutations of GFAP was determined by cell transfection and treatment in COS-7 cells. COS-7 cells were transfected either with AxD-causing variants GFAP-AEx4 and GFAP-I/D/F or wild type GFAP as described in example 3. 24 hours later cells expressing wild type GFAP were added to cells expressing the Alexander disease-causing forms of GFAP in a 1 : 1 ratio. 48 hours after transfections conditioned media were collected and processed as described above. IDE was detected by Western immunoblotting using enhanced chemiluminescence detection (ChemiDoc XRS, Bio-Rad). Signals were quantified with ImageJ (NIH).

The Figure 4 shows the quantification of IDE secretion given as the ratio of IDE in the medium to IDE in the lysates after Western immunoblot analysis of cells transfected with Alexander disease causing mutations GFAP-AEx4 or GFAP-I/D/F, and of probes of cells transfected with Alexander disease causing mutations GFAP-AEx4 or GFAP-I/D/F, to which were added cells transfected with GFAP wild type (GFAP-AEx4 + GFAP-wt) and (GFAP- I/D/F + GFAP-wt). It can be taken from the Figure 4 that the addition of cells overexpressing GFAP wild type, led to a 50% increase (dEx4) and in case of I/D/F mutation almost to a 100% increase in release of exosomes.

This suggests that a cell-based therapy could provide a viable approach to control the unconventional secretion pathway in case of certain Alexander disease-causing GFAP mutations. Example 7: in vivo study in Alexander disease model mice

To confirm the cell culture model findings on the therapeutic potential of the modulators of the unconventional secretory pathway, a single dose, randomized preclinical trial for two modulators Simvastatin (, Compound ) and Y-27632 (, Compound 2') was conducted in a mouse model of Alexander disease (AxD).

Controls included both wild-type FVB-mice and vehicle treated animals for all genotypes. The number of animals per group was five animals of both sexes which were randomly assigned to treatment groups. Two groups of mice were studied per experiment, a model of Alexander disease and wild-type controls. The mice used as a model of Alexander disease were characterized by point mutation R236H in GFAP representing most severe mutation in human patients.

Drugs or vehicle were administered to adult mice of an age of 4 to 8 weeks at the start via daily intraperitoneal injections for a period of four weeks. The vehicle was 2% dimethyl sulfoxide (DMSO) in saline. Drugs were dissolved in the vehicle and then sterilized through a 0.22 μιη filter prior to administration. The dose for each drug of 33 mg/kg body weight for simvastatin and 10 mg/kg for Y-27632 was well below the known LD50 and tested in cell culture as well as in FDA approved trials. Behavioral paradigms were tested on day 20. After four weeks the mice were euthanized and brains were collected for analyses of potential changes in gene expression and histopathology. 7.1 Behavioral analysis on grooming phenotype

For Alexander disease patients little information is present on behavioral or psychiatric changes due to the complexity and high diversity of their symptoms. To analyze the behavioral phenotype of mice, groups of GFAP knock-out mice (FVBA29S-Gfap ^tmlMes /J), of Alexander disease model mice, and of wild-type controls, were closely observed for a period of one month. The close observation of the GFAP knock-out mice and the Alexander disease model mice revealed changes in the grooming pattern, represented by the grooming attempts in 10 minutes as is shown in the Figures 5 A and 5B, respectively. While the GFAP knock-out mice (GFAP KO) showed a lower grooming than the wild type animals (Wt), the Alexander disease model mice (AxD) demonstrated an increase in grooming in comparison to the wild type and GFAP knock-out mice.

Using this behavior phenotype, it was tested whether the two modulators Simvastatin and Y- 27632 (, Compound 1 ' and , Compound 2') improve the grooming phenotype. On day 20 of the administration, the grooming attempts in 10 minutes were observed in wild type mice (Wt), Alexander disease model mice (AxD), and wild type and Alexander disease model mice treated with the modulators Simvastatin (comp. 1) and Y-27632 (comp. 2), respectively, and in vehicle treated AxD model mice. As is shown in the Figure 5B, there was no change in grooming behavior in case of the vehicle treated AxD model mice in comparison to the non- treated group, as can be seen in Figure 5B columns AxD vs. AxD Vehicle. Both, Simvastatin Compound 1 and Y-27632 Compound 2 were able to reduce grooming attempts in the AxD model mice comparison to the vehicle treated group, as can be seen in Figure 5B, columns AxD Comp. 1, AxD Comp. 2 vs AxD Vehicle. No changes were observed in the wild type mice as can be seen in Figure 5B, columns Wt, Wt Comp. 1, and Wt Comp. 2. These findings suggest that both compounds are able to alleviate GFAP-specific effects and do not have a general, unspecified behavior-altering properties. These finding further show that statins and Rho-associated protein kinase inhibitors can rescue grooming phenotype in the AxD model mice.

7.2 Behavioral analysis on paw clasping phenotype

Motor deficit is a common neurological problem in AxD patients, especially in the case of Type II AxD. One of the widely accepted readouts for motor deficit in mice is the paw clasping phenotype. Mice with normal motor functions exhibit no or very little paw clasping.

On day 20 of the administration, the paw clasping attempts in 1 minute were observed in wild type mice (Wt), Alexander disease model mice treated with vehicle (AxD Vehicle), and wild type mice and Alexander disease model mice treated with the modulators Simvastatin (comp. 1) and Y-27632 (comp. 2), respectively. The results are shown in the Figure 5C. An analysis of the AxD model mice revealed a significant increase in paw clasping in comparison to the wild type mice, as is shown in the Figure 5C, columns AxD Vehicle and Wt. This finding suggests that GFAP mutation in mice can also cause AxD-specific changes as in AxD patients.

Referring to the AxD model mice that were treated with the modulator Simvastatin

(Compound 1) there was a strong decrease in the number of clasping events in comparison to the vehicle treated animals, as can be seen in the Figure 5C, columns AxD Comp. 1 and AxD Vehicle. A similar effect was found in the group that was treated with modulator Y-27632 (Compound 2). The beneficial effect was however somewhat lower than in case of the compound 1, as can be seen in the Figure 5C, column AxD Comp. 2. In the wild type animals no significant difference in clasping phenotype was observed between the vehicle and the tested compounds. These finding further show that statins and Rho-associated protein kinase inhibitors can rescue the paw clasping phenotype in the AxD model mice.

7.3. Effect of the modulators Simvastatin and Y-27632 on the unconventional secretion pathway in the AxD model mice. Results from cell culture experiments suggested that an impairment of the unconventional secretion pathway (USP) can be one of the contributing factor to the AxD pathogenesis. To confirm this hypothesis, the level of Alix protein was analyzed in the brains from the wild type and AxD model mice after treatment. Alix/AIPl is a cytoplasmic protein, which has been defined as a regulator of the endo-lysosomal system and is used as a common marker for the unconventional secretion pathway (USP).

The level of Alix protein normalized to actin (ratio Alix/actin) for the wild type mice and Alexander disease model mice, and wild type and Alexander disease mice treated with the modulators Simvastatin (comp. 1) and Y-27632 (comp. 2), respectively, is shown in the Figure 5D. The AxD mice demonstrated an increased amount of Alix protein in the brain lysates, strongly indicating that the unconventional secretion pathway is impaired due to mutation in GFAP protein, as can be seen in the Figure 5D, columns Wt and AxD Vehicle. The AxD model mice that were treated either with the modulators Simvastatin (comp. 1) or Y-27632 (comp. 2) demonstrated a strong decrease in Alix protein compared to the wild type levels, as can be seen in the Figure 5D, columns AxD Comp. 1, Comp. 2 and Wt Comp. 1, Comp. 2, respectively. The observational study revealed that the AxD model animals had two behavioral phenotypes. First, AxD mutation in GFAP lead to an increased number of grooming attempts that is not present in the wild type and GFAP knock-out animals. Second, AxD model mice had an increased frontal paw clasping that is the indicator of a motor deficit that is also present in AxD patients. The biochemical analysis of brain lysates moreover reveled an accumulation of Alix protein. This finding is in line with the cell culture studies, confirming that an

impairment of the unconventional secretion pathway can be involved in the AxD

pathogenesis.

A treatment with the modulators of the unconventional secretory pathway selected from the statin simvastatin and the Rho-associated protein kinase inhibitor Y-27632 in this single dose preclinical trial strongly improved observed the behavioral phenotypes in the AxD model animals as well as successfully reduced the USP marker protein Alix in brain lysates. These results of the in vivo study indicate that the proposed therapeutic approach can improve some GFAP-specific behavioral abnormalities and provides a therapeutic option for use in the treatment of Alexander disease patients.

Example 8: individual therapeutic application in a patient with Type II Alexander disease To confirm the cell culture and animal model findings on therapeutic potential of the modulators of the unconventional secretory pathway, treatment with single dose for statins was conducted in a patient with Type II Alexander disease. For 6 months the patient was treated orally with statins. For the first two months, the patient was treated orally with 33 mg per day (1 tablet) simvastatin and then for next four months with 10 mg fluvastatin per day, because of intolerance to simvastatin. Cerebrospinal fluid (CSF) samples were collected before treatment and after seven months of therapy, proteins were separated with SDS-PAGE and glial fibrillary acidic protein (GFAP) and Alix protein were determined by Western immunoblotting. Figure 6A shows the protein levels of GFAP and Alix protein in the CSF samples collected before and after seven months of the therapy for samples of 5 μΐ and 10 μΐ, respectively. As can be seen in Figure 6A, GFAP and Alix levels considerably increased after treatment with simvastatin and fluvastatin in 10 μΐ CSF sample, while diffirence in 5 μΐ sample is less visible due to pipetting variation. This finding confirms the positive effect of statins on exosome release in an Alexander disease patient in vivo.

Swallow deficit is a very common symptom for many of the Type II AxD patients. Hence, 'Quality of Life in Swallowing Disorders' (SWAL-QOL) survey was used every forth week to assess changes of AxD-related symptoms. The standard Quality of Life in Swallowing Disorders questionnaire was used to evaluate the swallowing function and to ascertain the impact on the patient-perceived quality of life. Figure 6B shows the total SWAL-QOL score before and during the treatment with simvastatin and fluvastatin. Overall improvement was observed after 3 months of the treatment. Figure 6C shows the subset of SWAL-QOL score reflecting physical symptoms related to swallowing deficit before and during the therapy. Also in this subset, an improvement was observed after 3 months of the treatment. This indicated that the patient also reported a self-perceived improvement due to treatment with statins.