Therapeutic agent and therapeutic composition for huntington's disease

Abstract

The present invention addresses the problem of providing a therapeutic agent for Huntington's disease, a therapeutic composition for Huntington's disease or a therapeutic method for Huntington's disease for which no therapeutic agent has been developed so far.　The inventors of the present invention induced differentiation of iPS cells derived from a patient with Huntington's disease to striatal medium spiny neurons (MSNs) and found that by administering, to the striatal MSNs reflecting the pathology of Huntington's disease, a therapeutic agent for Huntington's disease containing a compound represented by formula (1-1), a compound represented by formula (2-1), a compound represented by formula (3-1), a compound represented by formula (4-1), a pharmaceutically acceptable salt thereof, or a solvate thereof, the pathology of Huntington's disease in the striatal MSNs was ameliorated.

Description

Huntington's disease therapeutic agent and therapeutic composition

[0001] An objective of the present invention is to develop a therapeutic agent or composition for treating Huntington's disease.

[0002] Huntington's disease is a hereditary neurodegenerative disorder that is inherited in an autosomal dominant manner and is characterized by clinical symptoms such as involuntary movements such as chorea, psychiatric symptoms, behavioral abnormalities, and cognitive impairment.

[0003] This disease is thought to be caused by an abnormal expansion of the CAG repeat sequence (CAG repeat) in the huntingtin (HTT) gene (IT15 gene) located on chromosome 4 in patients with Huntington's disease. Because this genetic abnormality is inherited and passed on to offspring, it is considered to be an autosomal dominant inheritance disease. Pathological findings have been observed in which abnormal HTT protein caused by this mutated HTT gene accumulates in cells.

[0004] The onset and timing of Huntington's disease is thought to be related to the number of CAG repeats in the HTT gene; Huntington's disease develops when there are 40 or more CAG repeats, and the greater the number of CAG repeats, the younger the age at which the disease tends to develop.

[0005] The incidence of the disease tends to vary slightly depending on race, with 0.7 cases per 100,000 people in Japan and 4-8 cases per 100,000 people in Caucasians.As of 2021, 918 cases have been reported in Japan, and the number in Europe and the United States is thought to be about 10 times that.

[0006] It is believed that Huntington's disease symptoms develop when the abnormal HTT protein described above forms aggregates with various structural forms, each of which exhibits different cytotoxicity, causing degeneration of nerve cells in the striatum and cerebral cortex.

[0007] The symptoms progress from initial symptoms, to motor symptoms, to involuntary movements, to psychiatric symptoms. The symptoms are as follows: Initial symptoms: Motor symptoms such as difficulty with fine motor skills, grimacing, and involuntary hand movements, as well as mental symptoms and behavioral abnormalities such as restlessness and depression; Motor symptoms: At first, people often have difficulty with fine motor skills (such as writing), are unable to continue the same movement, and may drop things or fall. As the disease progresses, symptoms include an unsteady gait, a tendency to stumble and fall, choking while eating, and difficulty speaking; Involuntary movements: symptoms such as rapid movements of the face and limbs that occur independently of one's will, irregular involuntary hand movements, neck movements, grimacing, and clicking the tongue (called chorea); Mental symptoms: Unlike ordinary dementia, people tend to have impaired abilities to plan and execute things, and to grasp the big picture, resulting in personality and behavioral changes such as irritability and abnormal repetition.

[0008] Currently, symptomatic treatments, such as the administration of medications to alleviate some of the symptoms of Huntington's disease, such as involuntary movements like chorea, and psychiatric symptoms like depression, personality disorders, and irritability, are used. Among these, tetrabenazine, an antipsychotic drug that inhibits dopamine reuptake (release suppression), is used to treat chorea.

[0009] However, currently, there are no drugs that can be used to treat Huntington's disease fundamentally (to improve motor function, psychiatric symptoms, and cognitive function), and no therapeutic method aimed at curing the disease has been established. Therefore, there is a need for the development of drugs or therapeutic methods that can improve motor function, psychiatric symptoms, and cognitive function.

[0010] Wu M., et al., A Chemical Recipe for Generation of Clinical-Grade Striatal Neurons from hESCs., Stem cell reports, 11(3), 2018Victor MB., et al., Generation of human striatal neurons by microRNA-dependent direct conversion of fibroblasts., Neuron, 84(2), 2015

[0011] An object of the present invention is to provide a therapeutic agent or composition for treating Huntington's disease, and a method for treating Huntington's disease, for which no therapeutic drug has been developed so far.

[0012] The inventors of the present invention have found that by inducing the differentiation of striatal medium spiny neurons (MSNs) from iPS cells derived from Huntington's disease patients and administering a therapeutic agent for Huntington's disease, described below, to striatal medium spiny neurons (MSNs) that reflect the pathology of Huntington's disease, the pathology of Huntington's disease in striatal medium spiny neurons (MSNs) is improved.

[0013] Based on this finding, the present invention has demonstrated that Huntington's disease can be treated with a therapeutic agent for Huntington's disease, which comprises a compound represented by the below-described formula (1-1), a compound represented by formula (2-1), a compound represented by formula (3-1), or a compound represented by formula (4-1), a pharmaceutically acceptable salt thereof, or a solvate thereof.

[0014] More specifically, in order to solve the above-mentioned problems, the present application provides the following aspects: [1]: A compound represented by the following formula (1-1):

[0015]

[0016] [In formula (1-1), R 1 each independently represents an alkyl group having 1 to 6 carbon atoms or a 4-hydroxyphenethyl group, and n represents an integer of 1 to 3.], a compound represented by the following formula (2-1):

[0017]

[0018] [In formula (2-1), R 21 is H or -CH3, R 22 is selected from the group consisting of H, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a halogen], a compound represented by the following formula (3-1):

[0019]

[0020] [In formula (3-1), Y is N or A 2 -C, Z represents N or CH, m is 0, 1, 2 or 3, B represents O, S or NR 33 indicates A 1 and A 2 are independently an optionally substituted alkyl group having 1 to 6 carbon atoms, an optionally substituted alkenyl group having 2 to 6 carbon atoms, an optionally substituted alkynyl group having 2 to 6 carbon atoms, an optionally substituted cycloalkyl group having 3 to 7 carbon atoms, an optionally substituted aryl group, an optionally substituted aryl-alkyl group having 1 to 6 carbon atoms, an optionally substituted heterocycloalkyl group having 3 to 7 carbon atoms, an optionally substituted heteroaryl group, or an optionally substituted heteroaryl-alkyl group having 1 to 6 carbon atoms, or H, halogen, cyano, trifluoromethyl, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, or -NR x R y where R x and R y independently represent H, a hydrocarbon group, or a heterocyclic group, or R x and R y together represent an alkylene group having 2 to 6 carbon atoms, and R 31 is -CH2CHR 34 NR 35 R 36 or the following formula:

[0021]

[0022] indicates R 32 , R33 , R 34 , R 35 , R 36 , and R 37 each independently represents H or an alkyl group having 1 to 6 carbon atoms, a compound represented by the following formula (4-1):

[0023]

[0024] [In formula (4-1), R 41 and R 42 is selected from an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an alkyl group having 1 to 6 carbon atoms substituted with an aryl group having 6 to 10 carbon atoms; R 43 is selected from alkyl groups having 1 to 6 carbon atoms, and M is selected from halogen and alkyl sulfate], a pharmaceutically acceptable salt thereof, or a solvate thereof; [2]: The therapeutic agent for Huntington's disease according to [1], wherein in formula (1-1), n ​​is 2. [3]: The therapeutic agent for Huntington's disease according to [1] or [2], wherein in formula (1-1), R1 is an n-propyl group. [4]: ​​The compound represented by formula (1-1) is a compound represented by the following formula (1-2):

[0025]

[0026] (4-[2-(dipropylamino)ethyl]-1,3-dihydro-2H-indol-2-one). [5]: The therapeutic agent for Huntington's disease according to claim [4], wherein the pharmaceutically acceptable salt of the compound represented by formula (1-1) is the hydrochloride salt of the compound represented by formula (1-2) (4-[2-(dipropylamino)ethyl]-1,3-dihydro-2H-indol-2-one hydrochloride). [6]: The therapeutic agent for Huntington's disease according to claim [4], wherein the compound represented by formula (2-1) is a compound represented by the following formula (2-2):

[0027]

[0028] The therapeutic agent for Huntington's disease according to [1] or [2], wherein the pharmaceutically acceptable salt of the compound represented by formula (2-1) is the hydrochloride salt of the compound represented by formula (2-2) (2-[3-[4-(m-chlorophenyl)-1-piperazinyl]propyl]-s-triazolo[4,3-a]pyridin-3(2H)-one hydrochloride). [7]: The therapeutic agent for Huntington's disease according to [6], wherein the pharmaceutically acceptable salt of the compound represented by formula (2-1) is the hydrochloride salt of the compound represented by formula (2-2) (2-[3-[4-(m-chlorophenyl)-1-piperazinyl]propyl]-s-triazolo[4,3-a]pyridin-3(2H)-one hydrochloride). [8]: The therapeutic agent for Huntington's disease according to [6], wherein the compound represented by formula (3-1) is the compound represented by formula (3-2):

[0029]

[0030] The therapeutic agent for Huntington's disease according to [1] or [2], wherein the pharmaceutically acceptable salt of the compound represented by formula (3-1) is a benzoate salt of a compound represented by formula (3-2) (N,N-dimethyl-2-[5-(1H-1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethanamine benzoate). [9]: The therapeutic agent for Huntington's disease according to [8], wherein the pharmaceutically acceptable salt of the compound represented by formula (3-1) is a benzoate salt of a compound represented by formula (3-2) (N,N-dimethyl-2-[5-(1H-1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethanamine benzoate).

[10] : The therapeutic agent for Huntington's disease according to [1] or [2], wherein the compound represented by formula (4-1) is a compound represented by the following formula (4-2):

[0031]

[0032] The therapeutic agent for Huntington's disease according to [1] or [2], wherein the compound is 3-dimethylcarbamoyloxy-1-methylpyridinium bromide.

[11] : A compound represented by the following formula (1-1):

[0033]

[0034] [In formula (1-1), R1's each independently represent an alkyl group having 1 to 6 carbon atoms or a 4-hydroxyphenethyl group, and n represents an integer of 1 to 3.], A compound represented by the following formula (2-1):

[0035]

[0036] [In formula (2-1), R21 is H or -CH3, R 22 is selected from the group consisting of H, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a halogen], a compound represented by the following formula (3-1):

[0037]

[0038] [In formula (3-1), Y is N or A 2 -C, Z represents N or CH, m is 0, 1, 2 or 3, B represents O, S or NR 33 indicates A 1 and A 2 are independently an optionally substituted alkyl group having 1 to 6 carbon atoms, an optionally substituted alkenyl group having 2 to 6 carbon atoms, an optionally substituted alkynyl group having 2 to 6 carbon atoms, an optionally substituted cycloalkyl group having 3 to 7 carbon atoms, an optionally substituted aryl group, an optionally substituted aryl-alkyl group having 1 to 6 carbon atoms, an optionally substituted heterocycloalkyl group having 3 to 7 carbon atoms, an optionally substituted heteroaryl group, or an optionally substituted heteroaryl-alkyl group having 1 to 6 carbon atoms, or H, halogen, cyano, trifluoromethyl, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, or -NR x R y where R x and R y independently represent H, a hydrocarbon group, or a heterocyclic group, or R x and R y together represent an alkylene group having 2 to 6 carbon atoms, and R 31 is -CH2CHR 34 NR 35 R 36 or the following formula:

[0039]

[0040] indicates R 32 , R 33 , R 34 , R 35 , R 36 , and R 37each independently represents H or an alkyl group having 1 to 6 carbon atoms, a compound represented by the following formula (4-1):

[0041]

[0042] [In formula (4-1), R 41 and R 42 is selected from an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an alkyl group having 1 to 6 carbon atoms substituted with an aryl group having 6 to 10 carbon atoms; R 43 is selected from alkyl groups having 1 to 6 carbon atoms, and M is selected from halogen and alkyl sulfate; or a pharmaceutically acceptable salt or solvate thereof as an active ingredient.

[0043] The therapeutic agent for Huntington's disease of the present invention is a compound obtained by screening using phenotypes characteristic of the human pathology as an evaluation item based on an analysis using striatal medium spiny neurons (MSNs) differentiated from iPS cells derived from Huntington's disease patients as a pathology model, and therefore can provide a therapeutic agent with high therapeutic efficacy against Huntington's disease.

[0044] Figure 1 shows a cell culture scheme for generating striatal medium spiny neurons (MSNs). Figure 2 shows immunostaining of differentiation-induced cells from healthy individuals, revealing cells positive for the MSN markers DARPP32 and DRD2. Figure 3 shows immunostaining of differentiation-induced cells, revealing the percentage of cells positive for the MSN markers DARPP32 and DRD2. Figure 4 shows the results of examining LDH leakage, a phenotype of striatal MSNs derived from Huntington's disease-specific iPS cells. This figure shows that the LDH leakage rate is significantly increased in MSNs derived from disease-specific iPS cells. Figure 5 shows the phenotype of striatal MSNs derived from Huntington's disease-specific iPS cells, revealing that MSNs derived from disease-specific iPS cells exhibit significantly reduced neurite length. Figure 6 shows the results of examining the neurite length phenotype of striatal MSNs derived from Huntington's disease-specific iPS cells, demonstrating that neurite length significantly regresses over time in MSN cells derived from disease-specific iPS cells. Figure 7 shows the phenotype of striatal MSNs derived from Huntington's disease-specific iPS cells, demonstrating that HTT aggregates significantly accumulate in MSN cells derived from disease-specific iPS cells. Figure 8 shows the results of examining the accumulation of HTT aggregates phenotype of striatal MSNs derived from Huntington's disease-specific iPS cells, demonstrating that HTT aggregates significantly accumulate over time in MSN cells derived from disease-specific iPS cells. Figure 9 shows a procedure for screening compounds for therapeutic agents for Huntington's disease using striatal MSNs derived from Huntington's disease-specific iPS cells. Figure 10-1 shows the pathological improvement rate (%) calculated based on three indicators when each of the eight compounds obtained in the compound screening was applied to cells with 180 CAG repeats (HD1.CAG180).Figure 10-2 shows the pathological improvement rate (%) calculated based on three indices when each of the eight compounds obtained in the compound screening was applied to cells with 50 CAG repeats (HD2.CAG50). Figure 11 shows the effect of various concentrations of ropinirole on neurite retraction. Figure 12 shows the effect of various concentrations of ropinirole on HTT aggregates. Figure 13 shows the procedure for examining the effect of ropinirole using striatal MSNs derived from Huntington's disease-specific iPS cells. Figure 14 shows the effect of various concentrations of ropinirole on LDH leakage using striatal MSNs derived from Huntington's disease-specific iPS cells. Figure 15 shows the effect of various concentrations of ropinirole on LDH leakage using striatal MSNs derived from Huntington's disease-specific iPS cells. Figure 16 shows the effect of various concentrations of ropinirole on HTT aggregates formed using striatal MSNs derived from Huntington's disease-specific iPS cells. Figure 17 shows the effect of various concentrations of ropinirole on HTT aggregates formed using striatal MSNs derived from Huntington's disease-specific iPS cells. Figure 18 shows the effect of various concentrations of ropinirole on LDH leakage using striatal MSNs derived from Huntington's disease-specific iPS cells, compared to bromocriptine at the same concentration range. Figure 19 shows the effect of various concentrations of ropinirole on LDH leakage caused by the addition of glutamate (50 μM) using striatal MSNs derived from Huntington's disease-specific iPS cells. Figure 20 shows the improvement rate of LDH leakage after application of 300 nM ropinirole to striatal-type MSNs derived from multiple Huntington's disease-specific iPS cells.

[0045] [Screening of therapeutic agents and pharmaceutical compositions for treating Huntington's disease] In the present invention, iPS cells are prepared from cells collected from a patient with Huntington's disease, and the iPS cells are induced to differentiate into striatal medium spiny neurons (MSNs). Striatal medium spiny neurons (MSNs) that reflect the pathology of Huntington's disease are used to screen each compound contained in a compound library using the following evaluation criteria: improvement of neurite retraction, suppression of HTT aggregate number, and neuroprotective effect (improvement of neuronal survival rate). This makes it possible to obtain compounds that ameliorate the pathology of Huntington's disease in striatal medium spiny neurons (MSNs) and have a therapeutic effect against Huntington's disease.

[0046] A method for inducing striatal medium spiny neurons (MSNs) is to induce differentiation of iPS cells into the lateral basal ganglia primordium by adding Sonic Hedgehog to Dual Smad inhibition (e.g., LDN-193189 and SB431542) and Wnt inhibition (e.g., Noggin and XAV939) genes, followed by the addition of Brain-derived neurotrophic factor (BDNF), Glial Cell Line-derived Neurotrophic Factor (GDNF), and ascorbic acid (Non-Patent Document 1). However, because this method requires a long time to induce differentiation and has low efficiency, which can lead to intercellular differences, a method for inducing differentiation by inducing gene expression in fibroblasts has been reported (Non-Patent Document 2). However, since this method is based on fibroblasts, the inventors of the present invention have demonstrated that inducing the gene expression of various transcription factors using iPS cells can induce differentiation of striatal medium spiny neurons (MSNs) in multiple cell lines in a short period of time.

[0047] Any compound library may be used for screening. For example, a library of compounds whose safety has been confirmed through clinical trials for various diseases can be used.

[0048] In the present invention, as a result of screening a compound library using this method, ropinirole, trazodone, rizatriptan, and pyridostigmine were selected as compounds that exhibit neurite retraction improving effects, HTT aggregate number suppressing effects, and neuroprotective effects (improving neuronal survival rate). Based on this finding, the inventors of the present invention have completed the present invention.

[0049] [Therapeutic agent for Huntington's disease, pharmaceutical composition for treating Huntington's disease] The present invention provides a compound represented by the following formula (1-1):

[0050]

[0051] [In formula (1-1), R1's each independently represent an alkyl group having 1 to 6 carbon atoms or a 4-hydroxyphenethyl group, and n represents an integer of 1 to 3.], A compound represented by the following formula (2-1):

[0052]

[0053] [In formula (2-1), R 21 is H or -CH3, R 22 is selected from the group consisting of H, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a halogen], a compound represented by the following formula (3-1):

[0054]

[0055] [In formula (3-1), Y is N or A 2 -C, Z represents N or CH, m is 0, 1, 2 or 3, B represents O, S or NR 33 indicates A 1 and A 2are independently an optionally substituted alkyl group having 1 to 6 carbon atoms, an optionally substituted alkenyl group having 2 to 6 carbon atoms, an optionally substituted alkynyl group having 2 to 6 carbon atoms, an optionally substituted cycloalkyl group having 3 to 7 carbon atoms, an optionally substituted aryl group, an optionally substituted aryl-alkyl group having 1 to 6 carbon atoms, an optionally substituted heterocycloalkyl group having 3 to 7 carbon atoms, an optionally substituted heteroaryl group, or an optionally substituted heteroaryl-alkyl group having 1 to 6 carbon atoms, or H, halogen, cyano, trifluoromethyl, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, or -NR x R y where R x and R y independently represent H, a hydrocarbon group, or a heterocyclic group, or R x and R y together represent an alkylene group having 2 to 6 carbon atoms, and R 31 is -CH2CHR 34 NR 35 R 36 or the following formula:

[0056]

[0057] indicates R 32 , R 33 , R 34 , R 35 , R 36 , and R 37 each independently represents H or an alkyl group having 1 to 6 carbon atoms, a compound represented by the following formula (4-1):

[0058]

[0059] [In formula (4-1), R 41 and R 42 is selected from an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an alkyl group having 1 to 6 carbon atoms substituted with an aryl group having 6 to 10 carbon atoms; R 43is selected from alkyl groups having 1 to 6 carbon atoms, and M is selected from halogen and alkyl sulfate], or a pharmaceutically acceptable salt or solvate thereof, and the present invention provides a therapeutic agent for Huntington's disease comprising the above compound, a pharmaceutically acceptable salt or solvate thereof, or a pharmaceutical composition for treating Huntington's disease comprising the above compound, a pharmaceutically acceptable salt or solvate thereof.

[0060] Diseases that can be treated with the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention include motor symptoms such as chorea and involuntary movements, cognitive symptoms such as dementia, and psychiatric symptoms. Furthermore, based on the pathological characteristics of patients with Huntington's disease, patients with HTT protein aggregate accumulation and various neurodegenerative diseases accompanied by the accumulation of other protein aggregate accumulation abnormalities (e.g., amyloid beta, α-syniclein, TAR DNA-binding protein of 43 kDa, fused in sarcoma, etc.) can be treated. Furthermore, based on the genetic characteristics of patients with Huntington's disease, patients with mutations in the HTT gene and patients with mutations in other genes in which aggregate protein accumulation has been reported (e.g., amyloid beta, α-syniclein, TAR DNA-binding protein of 43 kDa, fused in sarcoma, etc.) can be treated.

[0061] In the compound of formula (1-1) above, which is the active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention, n in formula (1-1) may be 1, 2, or 3. When the active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention is ropinirole, which will be described later, n in formula (1-1) is 2. Therefore, the active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention may be a compound in which n in formula (1-1) above is 2.

[0062] In addition, in the compound of the above formula (1-1) which is an active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention, 1 may be a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, more specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, n-pentyl, cyclopentyl, n-hexyl, cyclohexyl, etc. When the active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention is ropinirole, which will be described later, in formula (1-1), R 1 is an n-propyl group. Therefore, the active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention is a compound represented by the formula (1-1) above, 1 Regarding R 1 is an n-propyl group.

[0063] The compound represented by formula (1-1) above, which is the active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention, may be 4-[2-(dipropylamino)ethyl]-1,3-dihydro-2H-indol-2-one. That is, the compound represented by formula (1-1) above may be ropinirole. The chemical formula of ropinirole is shown in formula (1-2) below.

[0064]

[0065] Ropinirole was originally developed as a therapeutic agent for Parkinson's disease because of its dopamine D2 receptor (D2R) agonist activity in dopamine neurons. In the present invention, it is currently unclear whether ropinirole acts on Huntington's disease based on the same intracellular mechanism of action or a different intracellular mechanism. However, clinical trials have already been completed as a pharmaceutical, and its safety when administered to living organisms has been fully confirmed. Thus, because ropinirole is an existing drug, therapeutic agents for Huntington's disease or pharmaceutical compositions for treating Huntington's disease can be rapidly developed.

[0066] The compound represented by formula (2-1) above, which is the active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention, may be 2-[3-[4-(m-chlorophenyl)-1-piperazinyl]propyl]-s-triazolo[4,3-a]pyridin-3(2H)-one or its hydrochloride. That is, the compound represented by formula (2-1) above may be trazodone or its hydrochloride. The chemical formula of trazodone is shown in formula (2-2) below.

[0067]

[0068] Trazodone or its hydrochloride was originally developed as a therapeutic agent for depression and depressive state because it exhibits serotonin (5-HT) reuptake inhibitory activity and enhances reduced serotonergic neuronal function in patients with depression. In the present invention, it is currently unclear whether trazodone acts on Huntington's disease via the same intracellular mechanism or a different intracellular mechanism. However, clinical trials have already been completed as a pharmaceutical, and its safety when administered to living organisms has been fully confirmed. Thus, because trazodone or its hydrochloride is an existing drug, it can be rapidly developed into a therapeutic agent for Huntington's disease or a pharmaceutical composition for treating Huntington's disease.

[0069] The compound represented by formula (3-1), which is the active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention, may be N,N-dimethyl-2-[5-(1H-1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethanamine or its benzoate. That is, the compound represented by formula (3-1) may be rizatriptan or its benzoate. The chemical formula of rizatriptan is shown in formula (3-2) below.

[0070]

[0071] Rizatriptan or its benzoate salt was originally developed as a migraine treatment by acting on 5-HT1B receptors present in cranial vessels, selectively constricting extracranial arteries that are thought to dilate during migraine attacks, and by acting on peripheral and central inhibitory 5-HT1D receptors present in the trigeminal nerve, preventing the release of various peptides (substance P, calcitonin gene-related peptide, etc.), thereby suppressing vasodilation, dura inflammation, and central pain transmission. In the present invention, it is currently unclear whether rizatriptan or its benzoate salt acts on Huntington's disease via the same or a different intracellular mechanism of action. However, clinical trials have already been completed as a pharmaceutical, and its safety when administered to living organisms has been fully confirmed. Thus, because rizatriptan or its benzoate salt is an existing drug, it is possible to rapidly develop a therapeutic agent for Huntington's disease or a pharmaceutical composition for treating Huntington's disease.

[0072] The compound represented by formula (4-1), which is an active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention, may be 3-dimethylcarbamoyloxy-1-methylpyridinium bromide. That is, the compound represented by formula (4-1) may be pyridostigmine bromide. The chemical formula of pyridostigmine is shown below in formula (4-2).

[0073]

[0074] Pyridostigmine bromide was originally developed as a therapeutic agent for myasthenia gravis because it mainly inhibits cholinesterase activity at the neuromuscular junction, thereby suppressing the breakdown of acetylcholine, thereby indirectly enhancing the action of acetylcholine and also having acetylcholinemimetic activity itself. In the present invention, it is currently unclear whether pyridostigmine bromide acts on Huntington's disease based on the same intracellular mechanism of action or a different intracellular mechanism of action. However, clinical trials have already been completed as a pharmaceutical, and its safety when administered to living organisms has been fully confirmed. Thus, because pyridostigmine bromide is an existing drug, it can be quickly developed as a therapeutic agent for Huntington's disease or a pharmaceutical composition for treating Huntington's disease.

[0075] The active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention may be a salt of any of the compounds represented by the above formula (1-1), (2-1), (3-1), or (4-1); it may be a solvate of any of the compounds represented by the above formula (1-1), (2-1), (3-1), or (4-1); or it may be a solvate of a salt of any of the compounds represented by the above formula (1-1), (2-1), (3-1), or (4-1).

[0076] When a salt of any of the compounds represented by the above formula (1-1), (2-1), (3-1), or (4-1) is used as the active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention, the salt is not particularly limited as long as it is a pharmaceutically acceptable salt, and examples thereof include inorganic acid salts such as hydrochloride, sulfate, hydrobromide, nitrate, and phosphate; organic acid salts such as acetate, mesylate, succinate, maleate, fumarate, citrate, and tartrate; alkali metal salts such as sodium salt and potassium salt; alkaline earth metal salts such as magnesium salt and calcium salt; metal salts such as aluminum salt and zinc salt; ammonium salts such as ammonium salt and tetramethylammonium salt; organic amine addition salts such as morpholine and piperidine; and amino acid addition salts such as glycine, phenylalanine, lysine, aspartic acid, and glutamic acid.

[0077] Furthermore, when the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention uses any of the compounds represented by the above formula (1-1), the compounds represented by the above formula (2-1), the compounds represented by the above formula (3-1), or the compounds represented by the above formula (4-1), or a solvate of a salt thereof, the solvate is not particularly limited as long as it is a pharmaceutically acceptable solvate, and examples thereof include hydrates, organic solvates, etc.

[0078] The active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention may be 4-[2-(dipropylamino)ethyl]-1,3-dihydro-2H-indol-2-one hydrochloride, ie, ropinirole hydrochloride.

[0079] The active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention may be 2-[3-[4-(m-chlorophenyl)-1-piperazinyl]propyl]-s-triazolo[4,3-a]pyridin-3(2H)-one hydrochloride, i.e., trazodone hydrochloride.

[0080] The active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention may be N,N-dimethyl-2-[5-(1H-1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethanamine benzoate, i.e., rizatriptan benzoate.

[0081] The active ingredient of the therapeutic agent for Huntington's disease or the pharmaceutical composition for treating Huntington's disease of the present invention may be 3-dimethylcarbamoyloxy-1-methylpyridinium bromide, ie, pyridostigmine bromide.

[0082] The pharmaceutical composition for treating Huntington's disease of the present invention may be formulated as a pharmaceutical composition and can be administered orally in the form of, for example, tablets, capsules, elixirs, microcapsules, etc., or parenterally in the form of injections, suppositories, topical skin preparations, etc. More specific examples of topical skin preparations include dosage forms such as ointments and patches.

[0083] In the pharmaceutical composition for treating Huntington's disease of the present invention, the pharmaceutically acceptable carrier may be any carrier commonly used in the formulation of pharmaceutical compositions, without any particular limitation. More specifically, examples thereof include binders such as hypromellose, dextrin, macrogol 400, gelatin, corn starch, tragacanth gum, and gum arabic; excipients such as lactose hydrate, D-mannitol, starch, crystalline cellulose, and alginic acid; solvents for injections such as water, ethanol, and glycerin; and adhesives such as rubber-based adhesives and silicone-based adhesives.

[0084] The pharmaceutical composition for treating Huntington's disease of the present invention may contain additives, such as lubricants such as calcium stearate and magnesium stearate, sweeteners such as sucrose, lactose, saccharin, and maltitol, flavorings such as peppermint and rhizome oil, stabilizers such as carmellose sodium, hydrogenated oil, light anhydrous silicic acid, povidone, glycerin fatty acid esters, benzyl alcohol, and phenol, buffers such as phosphates and sodium acetate, solubilizers such as benzyl benzoate and benzyl alcohol, and colorants such as yellow ferric oxide, ferric oxide, black ferric oxide, and titanium oxide.

[0085] The pharmaceutical composition for treating Huntington's disease of the present invention can be formulated by appropriately combining the above-mentioned active ingredient with the above-mentioned pharmaceutically acceptable carriers and additives, and mixing them in a unit dosage form required for generally accepted pharmaceutical practice. The pharmaceutical composition for treating Huntington's disease of the present invention may use one active ingredient alone or two or more active ingredients in combination.

[0086] In general, an appropriate daily dose of a pharmaceutical composition for treating Huntington's disease of the present invention is an amount containing the minimum effective dose of the active ingredient to produce a therapeutic effect. This minimum effective dose depends on various factors, including the activity of the active ingredient contained in the pharmaceutical composition for treating Huntington's disease, functional group modifications that determine lipid solubility and water solubility, the route of administration, the time of administration, the excretion rate of the specific active ingredient used, the duration of treatment, other drugs, compounds, and / or substances used in combination, the age, sex, body weight, disease, health condition, and medical history of the patient, and other factors well known in the medical arts. Typically, the pharmaceutical composition for treating Huntington's disease of the present invention is administered to a patient at a daily dose containing about 0.0001 to about 100 mg / kg body weight of the active ingredient. The pharmaceutical composition for treating Huntington's disease of the present invention may be administered once a day or in divided doses about 2 to 4 times a day.

[0087] In particular, when the active ingredient is a compound represented by formula (1-2), the dosage of the pharmaceutical composition for treating Huntington's disease of the present invention is, for example, a sustained-release ropinirole formulation, such that 2 mg of the active ingredient is orally administered once a day, and the dosage is increased every week so as not to exceed 16 to 24 mg of the active ingredient per day.

[0088] In particular, when the active ingredient is a compound represented by formula (2-2), the dosage of the pharmaceutical composition for treating Huntington's disease of the present invention is, for example, 25 mg of the active ingredient orally administered three times a day, which may be increased every week, but is thought to be orally administered in a range not exceeding 75 to 200 mg of the active ingredient per day.

[0089] In particular, when the active ingredient is a compound represented by formula (3-2), the dosage of the pharmaceutical composition for treating Huntington's disease of the present invention is, for example, 10 mg of the active ingredient orally administered once a day, which may be increased every week, but is considered to be within the range of 10 to 20 mg of the active ingredient orally administered daily.

[0090] In particular, when the active ingredient is a compound represented by formula (4-2), the dosage of the pharmaceutical composition for treating Huntington's disease of the present invention is considered to be, for example, 60 mg of the active ingredient administered orally at a single time, not exceeding a maximum daily dose of 180 mg of the active ingredient.

[0091] [Other Embodiments] In another aspect, the present invention provides a method for treating Huntington's disease, comprising administering to a patient in need of such treatment any of the compounds represented by formula (1-1), (2-1), (3-1), and (4-1), or a pharmaceutically acceptable salt thereof, or a solvate thereof. In this aspect of the present invention, the compound represented by formula (1-1), (2-1), (3-1), and (4-1), or a pharmaceutically acceptable salt thereof, or a solvate thereof used as the active ingredient may be the same as those described above. In addition, in this aspect of the present invention, the dosage of the active ingredient can be determined by considering the appropriate dosage for each compound. For example, the dosage is as described above when ropinirole is used as the active ingredient.

[0092] The present invention provides a compound represented by formula (1-1), a compound represented by formula (2-1), a compound represented by formula (3-1), or a compound represented by formula (4-1), or a pharmaceutically acceptable salt thereof, or a solvate thereof, for treating Huntington's disease. In this aspect of the present invention, the compound represented by formula (1-1), a compound represented by formula (2-1), a compound represented by formula (3-1), or a compound represented by formula (4-1), or a pharmaceutically acceptable salt thereof, or a solvate thereof, can be the same as those described above.

[0093] The present invention will be specifically illustrated by the following examples, which are not intended to limit the present invention in any way.

[0094] Example 1 Screening of Compounds for the Treatment of Huntington's Disease In this example, disease-specific iPS cells derived from cells of a patient with Huntington's disease were used to induce differentiation of striatal medium spiny neurons (MSNs) that can be used to screen for compounds for the treatment of Huntington's disease, and compounds that can ameliorate the pathology of Huntington's disease in the striatal MSNs were screened.

[0095] (1-1) Differentiation and induction of striatal medium spiny neurons (MSNs) Huntington's disease is known to have various pathological conditions due to an increase in the number of CAG repeats in the huntingtin gene (HTT gene). In the present invention, iPS cells derived from patient individuals (5 lines) with various numbers of CAG repeats and iPS cells derived from healthy individuals (3 lines) were used as disease-specific iPS cells, and were induced to differentiate into striatal MSNs based on the culture method shown in Figure 1.

[0096] The iPS cells used herein are as follows: Disease-specific iPS cells HD1.CAG180; 180 CAG repeats HD2.CAG50; 50 CAG repeats HD3.CAG47; 47 CAG repeats HD4.CAG50; 50 CAG repeats HD5.CAG42; 42 CAG repeats iPS cells derived from healthy individuals ND50018: ND50025: RC802:

[0097] Specifically, each cell line was first transfected with a plasmid containing the microRNA9 / 124, ASCL1, BCL2L1, CTIP2, MYT1L, and FOXP1 / 2 genes linked to a promoter whose expression is induced in the presence of doxycycline (DOX) using the PiggyBac method. The cells were then induced with doxycycline (CAS number: 24390-14-5) at a final concentration of 2 μg / mL for 7 days to express the ASCL1, BCL2L1, CTIP2, MYT1L, and FOXP1 / 2 proteins, which are transcription factors expressed in the early stage of neuronal differentiation. At the same time, the cells were transfected with BDNF (CAS number: 218441-99-7) at a final concentration of 10 ng / mL and BDNF (CAS number: 218441-99-7) at a final concentration of 10 ng / mL. Striatal medium spiny neurons (MSNs) were induced by culturing the cells in Neurobasal plus™ medium (Thermo Fisher Scientific A3582901) (Medium A) containing 200µg / ml neurotrophin-3 (NT-3) (CAS No. 130939-66-1), 1µM valproic acid (CAS No. 1069-66-5), 200µM dibutyl-cAMP (dbcAMP) (CAS No. 16980-89-5), 1µM retinoic acid (RA) (CAS No. 302-79-4), and 2% B27™ Supplement (Thermo Fisher Scientific 12587010) for 7 days. Cytarabine (Ara-C) was added to the medium at a final concentration of 2µM on days 1 and 3 to inhibit astrocyte proliferation. The medium was changed every 2 to 3 days.

[0098] Subsequently, the cells were cultured in Brainphys™ Neuronal Medium (STEMCELL Technologies, ST-05790) containing BDNF (CAS No.: 218441-99-7) at a final concentration of 10 ng / ml, neurotrophin-3 (NT-3) (CAS No.: 130939-66-1) at a final concentration of 10 ng / ml, valproic acid (CAS No.: 1069-66-5) at a final concentration of 1 μM, dibutyl-cAMP (dbcAMP) (CAS No.: 16980-89-5) at a final concentration of 200 μM, retinoic acid (RA) (CAS No.: 302-79-4) at a final concentration of 1 μM, B27™ Supplement (Thermo Fischer scientific, 12587010) at a final concentration of 2%, and CultureOne™ Supplement (Gibco, A3320201) at a final concentration of 0.1%. B) and cultured for 28 days until Day 35. DAPT (CAS number: 208255-80-5) was added to the medium at a final concentration of 1 μM only when the medium was changed on Day 8. The medium was changed every 2 to 3 days.

[0099] The differentiation-induced cells from healthy individuals were immunostained to examine the expression of the MSN markers DARPP32 and DRD2. The results are shown in Figure 2. The results indicated that DARPP32 and DRD2 were expressed along with the pan-neuronal marker TUJ1. The proportion of DARPP32- and DRD2-positive cells among the resulting neurons was examined, and the proportions were similar in MSNs generated from iPS cells derived from Huntington's disease patients to those generated from iPS cells derived from healthy individuals. These results demonstrate that the cells induced to differentiate using the above procedure are striatal-type MSNs.

[0100] We further investigated whether the differentiated striatal MSNs derived from Huntington's disease-specific iPS cells exhibited physiological indices specific to Huntington's disease. These physiological indices were measured using lactate dehydrogenase (LDH) leakage, a marker of neuronal cell death, neurite length retraction, and HTT aggregate accumulation. LDH leakage was measured using a commercially available kit (Model "G7891"; Promega). Neurite length was measured by immunostaining with the TUJ1 antibody on days 7, 14, 21, 28, and 35, and image analysis was performed using the immunostained data to quantify neurite length over time up to 35 days after the start of culture. HTT aggregate accumulation was measured by immunostaining with HTT and polyglutamine antibodies on days 7, 14, 21, 28, and 35, and image analysis was performed using the immunostained data to quantify HTT aggregates over time up to 35 days after the start of culture. All measurements were quantified as a ratio to the average value obtained using MSNs produced from iPS cells derived from healthy individuals.

[0101] Compared with results obtained with MSNs generated from iPS cells derived from healthy individuals, all striatal-type MSNs derived from Huntington's disease-specific iPS cells showed significantly increased LDH leakage (Figure 4), significantly reduced neurite length (Figures 5 and 6), and significant accumulation of HTT aggregates (Figures 7 and 8) (Figures 5 and 7 show results using cells on day 35). These results demonstrate that the resulting MSNs exhibit Huntington's disease-specific pathology as a phenotype. In Figures 4, 6, and 8, "*" and "**" indicate significant differences at a risk level of less than 5% or less than 1%, respectively.

[0102] (1-2) Results of Drug Discovery Screening Using Striatal Medium Spiny Neurons (MSNs) Using striatal MSNs derived from Huntington's disease-specific iPS cells induced to differentiate as described in (1-1) above, we screened existing drug libraries for drugs that reverse the Huntington's disease phenotype, using the phenotypes shown in (1-1) as indicators: reduced LDH leakage, neurite length, and reduced HTT aggregate accumulation. Measurement of LDH leakage, neurite length, and quantification of HTT aggregates were performed using the same methods as described in Example (1-1). Two types of iPS cells, HD1.CAG180 and HD2.CAG50, were used for screening.

[0103] As shown in Figure 9, each compound from the existing drug library was added to the culture medium on days 29 to 34 after the start of differentiation induction, and screening was then performed. As a result, eight drugs were identified as promising therapeutic agents for Huntington's disease. The percentage of improvement in the Huntington's disease phenotype when these drugs were added to the culture medium was calculated.

[0104] The percent improvement of Huntington's disease phenotypes for each parameter was calculated using the following formula (1): Improvement (%) = (AB) / (AC) × 100 (1). (In formula (1), A represents the measured value of striatal medium spiny neurons (MSNs) differentiated from iPS cells derived from HD patients in the absence of drug, B represents the measured value of striatal medium spiny neurons (MSNs) differentiated from iPS cells derived from HD patients in the presence of drug, and C represents the measured value of striatal medium spiny neurons (MSNs) differentiated from iPS cells derived from healthy individuals in the absence of drug.) The maximum percentages of LDH leakage, neurite retraction, and HTT aggregate accumulation phenotypes were set at 35%, 35%, and 30%, respectively, totaling 100%.

[0105] The results of adding the eight drugs obtained above at final concentrations of 0.01 μM, 0.1 μM, 1 μM, and 10 μM to the culture medium of striatal medium spiny neurons (MSNs) differentiated from iPS cells (HD1.CAG180 and HD2.CAG50) derived from HD patients are shown in Figure 10. Ropinirole, trazodone, rizatriptan, and pyridostigmine exhibited high neuroprotective effects within the range of 0.01 μM to 10 μM, calculated as the percentage improvement in Huntington's disease phenotypes, with the percentages of LDH leakage, neurite retraction, and HTT aggregate accumulation taken as 100%.

[0106] Based on these results, we selected ropinirole as the target of further investigation. Immunostaining of cells also demonstrated that ropinirole improved neurite retraction (Figure 11, using HD2.CAG50 cells) and HTT aggregates (Figure 12, using HD1.CAG180 cells). Table 1 shows the improvement rates of each phenotype by ropinirole for both cells (HD1.CAG180 and HD2.CAG50).

[0107]

[0108] Example 2: Effect of ropinirole In this example, functional analysis of ropinirole obtained in Example 1 (1-2) was performed using striatal medium spiny neurons (MSNs) generated using disease-specific iPS cells derived from cells of a patient with Huntington's disease.

[0109] (2-1) Procedure for cell treatment with ropinirole The efficacy of ropinirole was evaluated in the same manner as in Example 1 (1-2), except that the timing of adding ropinirole to the culture was changed to 29 to 36 days after the start of differentiation induction, as shown in Figure 13.

[0110] Specifically, ropinirole was added to the culture medium of striatal medium spiny neurons (MSNs) differentiated from iPS cells derived from Huntington's disease patients with HTT gene mutations (HD1.CAG180, HD2.CAG50, HD3.CAG47) on days 29, 31, and 34, and assays were performed on day 36. Ropinirole was added to the culture medium at final concentrations of 10 nM, 100 nM, and 1000 nM.

[0111] (2-2) Neuroprotective Effect of Ropinirole As a parameter of neuroprotective effect, the LDH leakage rate due to ropinirole administration was measured. The LDH leakage rate was measured in the same manner as in Example 1 (1-2). The results are shown in Figures 14 and 15.

[0112] Figure 14 is a graph showing the results of measuring LDH leakage rates in striatal medium spiny neurons (MSNs) differentiated from iPS cells derived from Huntington's disease patients with different CAG repeat numbers (HD1.CAG180, HD2.CAG50, HD3.CAG47) when various concentrations of ropinirole (10 nM, 100 nM, 1000 nM) were added to the culture medium. The vertical axis of Figure 14 shows the LDH leakage rate (relative value) when various concentrations of ropinirole were added, based on the LDH leakage value without ropinirole. The horizontal axis shows the results when ropinirole was added to the culture medium at 10 nM, 100 nM, or 1000 nM. In Figure 14, "*" indicates a significant difference at a level of less than 5%, and "**" indicates a significant difference at a level of less than 1%.

[0113] Figure 15 is a graph showing the results of measuring LDH leakage rates in striatal medium spiny neurons (MSNs) differentiated from iPS cells derived from Huntington's disease patients with different CAG repeat numbers (HD1.CAG180, HD2.CAG50, and HD5.CAG42) when various concentrations of ropinirole (0.1 nM, 1 nM, 10 nM, 30 nM, 100 nM, and 300 nM) were added to the culture medium. The vertical axis of Figure 15 shows the LDH leakage rate (relative value) when various concentrations of ropinirole were added, based on the LDH leakage value without ropinirole. The horizontal axis shows the results when ropinirole was added to the culture medium at 0.1 nM, 1 nM, 10 nM, 30 nM, 100 nM, or 300 nM. In FIG. 15, "*" indicates that there is a significant difference at a risk level of less than 5%, and "**" indicates that there is a significant difference at a risk level of less than 1%.

[0114] The results in Figures 14 and 15 show that the addition of ropinirole exerted a neuroprotective effect (reduced LDH leakage) even on days 29 to 36 after the start of differentiation induction. Furthermore, the EC50 of ropinirole in Figure 14 was 10 nM or less (calculated using ImageJ and Excel), and the IC50 of ropinirole in Figure 15 was 64.2 nM (calculated using ImageJ and Excel), demonstrating that ropinirole exerts a neuroprotective effect at very low doses.

[0115] (2-3) Effect of Ropinirole on HTT Aggregate Accumulation Improvement HTT aggregate accumulation, a physiological indicator specific to Huntington's disease, was measured in striatal medium spiny neurons (MSNs) derived from differentiation-induced Huntington's disease-specific iPS cells. Changes in the HTT aggregate accumulation rate due to ropinirole administration were measured as a parameter for the effect of improving HTT aggregate accumulation. The HTT aggregate accumulation rate was measured as in Example 1. The results are shown in Figures 16 and 17.

[0116] Figure 16 shows immunostaining results of striatal medium spiny neurons (MSNs) differentiated from iPS cells derived from Huntington's disease patients with different CAG repeat numbers (HD1.CAG180, HD2.CAG50, and HD5.CAG42). The addition of ropinirole to the culture medium at various concentrations (10 nM, 30 nM, 100 nM, and 300 nM) improved HTT aggregate accumulation. The arrows in Figure 16 indicate the sites of HTT aggregate accumulation, and the horizontal axis shows the results of adding ropinirole to the culture medium at 10 nM, 30 nM, 100 nM, or 300 nM.

[0117] Figure 17 is a graph quantifying the results of Figure 16. The vertical axis of Figure 17 shows the HTT aggregate accumulation rate (relative value) when various concentrations of ropinirole were added, with the number of HTTs in the absence of ropinirole as the reference, and the horizontal axis shows the results when ropinirole was added to the medium at 10 nM, 30 nM, 100 nM, or 300 nM. In Figure 17, "*" indicates that there is a significant difference at a level of less than 5%, and "**" indicates that there is a significant difference at a level of less than 1%.

[0118] The results in Figures 16 and 17 show that the addition of ropinirole improved HTT aggregate accumulation (reduced the HTT aggregate accumulation rate) even on days 29 to 36 after the start of differentiation induction. Furthermore, the IC50 of ropinirole was 40.5 nM (calculated using ImageJ and Excel), demonstrating that it can improve HTT aggregate accumulation at a very low dose.

[0119] (2-4) Neuroprotective Effect of Ropinirole Compared to the Same Agonist Ropinirole originally possesses dopamine D2 receptor (D2R) agonist activity in dopamine neurons. Therefore, bromocriptine, another D2 receptor agonist, was used to compare the neuroprotective effect of bromocriptine with that of ropinirole. As a parameter of neuroprotective effect, the LDH leakage rate following ropinirole administration was measured. The LDH leakage rate was measured as in Example 1. The results are shown in Figure 18.

[0120] Figure 18 shows the results of measuring LDH leakage in striatal medium spiny neurons (MSNs) differentiated from Huntington's disease patient-derived iPS cells (HD1.CAG180, HD2.CAG50, and HD5.CAG42) in the presence of various concentrations of ropinirole or bromocriptine (a D2 receptor agonist) in the culture medium. The vertical axis of Figure 18 shows the relative LDH leakage rate in the absence of ropinirole, while the horizontal axis shows the results obtained with ropinirole at 1 nM, 30 nM, or 300 nM or bromocriptine at 1 nM, 30 nM, or 300 nM. In Figure 15, "*" indicates a significant difference at a level of less than 5%, and "**" indicates a significant difference at a level of less than 1%.

[0121] As a result, from 29 to 36 days after the start of differentiation induction, the addition of ropinirole exerted a neuroprotective effect (reduced LDH leakage), but bromocriptine did not. This indicates that ropinirole, a D2 receptor agonist, exerts a more neuroprotective effect than bromocriptine, another D2 receptor agonist.

[0122] (2-5) Neuroprotective Effect of Ropinirole Against Glutamate-Induced Cell Death Excessive glutamate neurostimulation causes neurons to become overexcited, leading to their inability to tolerate the stimulation and resulting in spontaneous cell death. This phenomenon, known as glutamate neuroexcitotoxicity, is believed to be the cause of various neurodegenerative diseases. To confirm whether ropinirole has a neuroprotective effect against glutamate-induced neuroexcitotoxicity, the LDH leakage rate following ropinirole administration was measured as a parameter for neuroprotection. The LDH leakage rate was measured as in Example 1. The results are shown in Figure 19.

[0123] Figure 19 is a graph showing the results of measuring LDH leakage rates in striatal medium spiny neurons (MSNs) differentiated from Huntington's disease patient-derived iPS cells (HD2.CAG50) when glutamate and various concentrations of ropinirole were added to the culture medium. The vertical axis of Figure 19 shows the relative LDH leakage rates (relative values) for cells with 50 μM glutamate added and various concentrations of ropinirole added, relative to the LDH leakage values ​​in the absence of glutamate or ropinirole. The horizontal axis shows the results when ropinirole was added to the culture medium at 10 nM, 100 nM, or 1000 nM. The "+" on the horizontal axis of Figure 19 indicates the medium containing 50 μM glutamate. In Figure 19, "*" indicates a significant difference at a level of less than 5%, and "**" indicates a significant difference at a level of less than 1%.

[0124] As a result, on days 29 to 36 after the start of differentiation induction, the addition of glutamate induced neuronal cell death, but the addition of ropinirole exerted a neuroprotective effect (reduced LDH leakage), indicating that ropinirole exerts a neuroprotective effect against excessive stimulation of glutamate receptors.

[0125] (2-6) Neuroprotective effect of ropinirole using various HD strains As a parameter of the neuroprotective effect of ropinirole administration, the LDH leakage rate due to ropinirole administration was measured, and the effect of adding ropinirole on improving the LDH leakage rate was examined based on the change in the LDH leakage rate. The LDH leakage improvement rate was calculated as in Example 1 (1-2). The results are shown in Figure 20.

[0126] Figure 20 is a graph showing the improvement in LDH leakage after ropinirole application, based on the results of measurements of LDH leakage rates in striatal medium spiny neurons (MSNs) differentiated from Huntington's disease patient-derived iPS cells (HD1.CAG180, HD2.CAG50, HD3.CAG47, HD4.CAG50, and HD5.CAG42) when 300 nM ropinirole was added to the culture medium. The horizontal axis of Figure 20 shows the improvement in LDH leakage (relative value) from the LDH leakage value before ropinirole application (0 nM) to the LDH leakage value after ropinirole application (300 nM), with the LDH leakage value in a healthy subject sample taken as the reference (100%). The vertical axis shows the results of adding ropinirole to the culture medium for each cell type (0 nM or 300 nM). In FIG. 20, "*" indicates that there is a significant difference at a risk level of less than 5%, and "**" indicates that there is a significant difference at a risk level of less than 1%.

[0127] As a result, the addition of ropinirole on days 29 to 36 after the start of differentiation induction demonstrated a neuroprotective effect (improvement of LDH leakage), demonstrating that the neuroprotective effect of ropinirole is effective in treating patients with a wide range of HTT CAG repeat numbers.

[0128] According to the present invention, it is possible to provide a therapeutic agent for Huntington's disease and a composition for treating Huntington's disease. The therapeutic agent for Huntington's disease or composition for treating Huntington's disease of the present invention can be used not only to treat Huntington's disease but also to prevent the onset of Huntington's disease. Furthermore, by analyzing the mechanism of efficacy of the therapeutic agent for Huntington's disease of the present invention on striatal medium spiny neurons (MSNs) differentiated from iPS cells derived from Huntington's disease patients, it is possible to elucidate the pathological mechanism of Huntington's disease.

Claims

1. A compound represented by the following formula (1-1): [In formula (1-1), R 1 each independently represents an alkyl group having 1 to 6 carbon atoms or a 4-hydroxyphenethyl group, and n represents an integer of 1 to 3.], a compound represented by the following formula (2-1): [In formula (2-1), R 21 is H or -CH3, R 22 is selected from the group consisting of H, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a halogen], a compound represented by the following formula (3-1): [In formula (3-1), Y is N or A 2 -C, Z represents N or CH, m is 0, 1, 2 or 3, B represents O, S or NR 33 indicates A 1 and A 2 are independently an optionally substituted alkyl group having 1 to 6 carbon atoms, an optionally substituted alkenyl group having 2 to 6 carbon atoms, an optionally substituted alkynyl group having 2 to 6 carbon atoms, an optionally substituted cycloalkyl group having 3 to 7 carbon atoms, an optionally substituted aryl group, an optionally substituted aryl-alkyl group having 1 to 6 carbon atoms, an optionally substituted heterocycloalkyl group having 3 to 7 carbon atoms, an optionally substituted heteroaryl group, or an optionally substituted heteroaryl-alkyl group having 1 to 6 carbon atoms, or H, halogen, cyano, trifluoromethyl, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, or -NR x R y where R x and R y independently represent H, a hydrocarbon group, or a heterocyclic group, or R x and R y together represent an alkylene group having 2 to 6 carbon atoms, and R 31 is -CH2CHR 34 NR 35 R 36 or the following formula: indicates R 32 , R 33 , R 34 , R 35 , R 36 , and R 37 each independently represents H or an alkyl group having 1 to 6 carbon atoms, a compound represented by the following formula (4-1): [In formula (4-1), R 41 and R 42 is selected from an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an alkyl group having 1 to 6 carbon atoms substituted with an aryl group having 6 to 10 carbon atoms; R 43 is selected from alkyl groups having 1 to 6 carbon atoms, and M is selected from halogen and alkyl sulfate; or a pharmaceutically acceptable salt thereof, or a solvate thereof.

2. The therapeutic agent for Huntington's disease according to claim 1, wherein n is 2 in formula (1-1).

3. In the formula (1-1), R 1 3. The therapeutic agent for Huntington's disease according to claim 1 or 2, wherein is an n-propyl group.

4. The compound represented by formula (1-1) is a compound represented by formula (1-2):

3. The therapeutic agent for Huntington's disease according to claim 1, wherein the therapeutic agent is (4-[2-(dipropylamino)ethyl]-1,3-dihydro-2H-indol-2-one).

5. The therapeutic agent for Huntington's disease according to claim 4, wherein the pharmaceutically acceptable salt of the compound represented by formula (1-1) is the hydrochloride salt of the compound represented by formula (1-2) (4-[2-(dipropylamino)ethyl]-1,3-dihydro-2H-indol-2-one hydrochloride).

6. The compound represented by formula (2-1) is a compound represented by formula (2-2):

3. The therapeutic agent for Huntington's disease according to claim 1, wherein the compound is (2-[3-[4-(m-chlorophenyl)-1-piperazinyl]propyl]-s-triazolo[4,3-a]pyridin-3(2H)-one).

7. The therapeutic agent for Huntington's disease according to claim 6, wherein the pharmaceutically acceptable salt of the compound represented by formula (2-1) is the hydrochloride salt of the compound represented by formula (2-2) (2-[3-[4-(m-chlorophenyl)-1-piperazinyl]propyl]-s-triazolo[4,3-a]pyridin-3(2H)-one hydrochloride).

8. The compound represented by formula (3-1) is a compound represented by formula (3-2):

3. The therapeutic agent for Huntington's disease according to claim 1, wherein the therapeutic agent is N,N-dimethyl-2-[5-(1H-1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethanamine.

9. The therapeutic agent for Huntington's disease according to claim 8, wherein the pharmaceutically acceptable salt of the compound represented by formula (3-1) is a benzoate salt of the compound represented by formula (3-2) (N,N-dimethyl-2-[5-(1H-1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethanamine benzoate).

10. The compound represented by formula (4-1) is a compound represented by formula (4-2):

3. The therapeutic agent for Huntington's disease according to claim 1, wherein the therapeutic agent is 3-dimethylcarbamoyloxy-1-methylpyridinium bromide.

11. A compound represented by the following formula (1-1): [In formula (1-1), R 1 each independently represents an alkyl group having 1 to 6 carbon atoms or a 4-hydroxyphenethyl group, and n represents an integer of 1 to 3.], a compound represented by the following formula (2-1): [In formula (2-1), R 21 is H or -CH3, R 22 is selected from the group consisting of H, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a halogen], a compound represented by the following formula (3-1): [In formula (3-1), Y is N or A 2 -C, Z represents N or CH, m is 0, 1, 2 or 3, B represents O, S or NR 33 indicates A 1 and A 2 are independently an optionally substituted alkyl group having 1 to 6 carbon atoms, an optionally substituted alkenyl group having 2 to 6 carbon atoms, an optionally substituted alkynyl group having 2 to 6 carbon atoms, an optionally substituted cycloalkyl group having 3 to 7 carbon atoms, an optionally substituted aryl group, an optionally substituted aryl-alkyl group having 1 to 6 carbon atoms, an optionally substituted heterocycloalkyl group having 3 to 7 carbon atoms, an optionally substituted heteroaryl group, or an optionally substituted heteroaryl-alkyl group having 1 to 6 carbon atoms, or H, halogen, cyano, trifluoromethyl, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, or -NR x R y where R x and R y independently represent H, a hydrocarbon group, or a heterocyclic group, or R x and R y together represent an alkylene group having 2 to 6 carbon atoms, and R 31 is -CH2CHR 34 NR 35 R 36 or the following formula: indicates R 32 , R 33 , R 34 , R 35 , R 36 , and R 37 each independently represents H or an alkyl group having 1 to 6 carbon atoms, a compound represented by the following formula (4-1): [In formula (4-1), R 41 and R 42 is selected from an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an alkyl group having 1 to 6 carbon atoms substituted with an aryl group having 6 to 10 carbon atoms; R 43 is selected from alkyl groups having 1 to 6 carbon atoms, and M is selected from halogen and alkyl sulfate; or a pharmaceutically acceptable salt or solvate thereof as an active ingredient.

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