Alpha-methyl-p-tyrosine and specific derivatives thereof for use in the treatment of Parkinson's disease and / or parkinsonism

Abstract

Method for treating Parkinson's disease, Huntington's disease and other similar diseases with abnormal dopaminergic neurotransmission, by using systemically administered small molecules that penetrate the central nervous system to inhibit the rate-limiting step of dopamine synthesis in the central nervous system, the conversion of L-tyrosine to L-3,4-dihydroxyphenylalanine (L-DOPA) by tyrosine hydroxylase together with its cofactors tetrahydrobiopterin and iron (Fe+).

Description

FIELD OF INVENTION

[0001] The present invention is composition for use in a novel method of treating Parkinson's Disease and the like, diseases with abnormal dopamine-neurotransmission, using small molecules administered systemically that penetrate into the central nervous system to inhibit the rate-limiting step of dopamine synthesis in the central nervous system, the conversion of L-tyrosine to L-3, 4-dihydroxyphenylalanine (L-DOPA) by tyrosine hydroxylase along with its cofactors tetrahydrobiopterin and iron (Fe +< ) as definef in the appended claims.BACKGROUND

[0002] Abnormalities in dopamine neurotransmission underlie movement disorders, as exemplified by Parkinson's and Huntington's diseases.

[0003] Parkinson's disease manifests initially as a movement disorder, progressing from tremors to the combination of muscle rigidity and akinesia. Widespread neurologic impairment follows. The biologic hallmarks include loss of dopaminergic neurons in the brain (in the substantia nigra, largely in the pars compacta, within the basal ganglia) with protein accumulation (Lewy Bodies) and oxidative stress that impair function of the remaining cells (Fahn, S., Parkinsonism and Related Disorders The 200-year journey of Parkinson disease: Reflecting on the past and looking towards the future, Parkinsonism Relat. Disord. 46, 1-5 (2017)). With loss of these neuronal cell bodies, their axonal projections into the caudate nucleus and putamen of the midbrain are lost and / or lose their ability to synthesize and release dopamine.

[0004] The disease is the second most prevalent cause of neurologic degeneration and loss of independent function, affecting millions globally (National Institute for Health and Care Excellence, Parkinson 's Disease in Adults: Diagnosis and Management. NICE Guideline NG71. (2017)).

[0005] This model of disease was reinforced in the 1970s with landmark Parkinson's studies demonstrating loss of dopaminergic neurons in the substantia nigra (Damier, P. et al., The substantia nigra of the human brain: II. Patterns of loss of dopamine-containing neurons in Parkinson's disease, Brain 122, 1437-1448 (1999)). that correlated with reduction in dopamine levels (Bernheimer et al., Brain Dopamine and the Syndromes of Parkinson, J. Neurol. Sci. 4, 145-148 (1973)). Post mortem studies linked these neurochemical abnormalities to motor dysfunction (Hartmann, A., Postmortem studies in Parkinson's disease, Dialogues Clin. Neurosci. 6, 281-293 (2004), Hirsch et al., Melanized dopaminergic neurons are differentially susceptible to degeneration in Parkinson's disease, Nature 334, 345-348 (1988)). Thus, medicines to increase dopamine levels in the caudate nucleus and putamen became the foundation of Parkinson's treatment, based on the rationale that pharmacologic levels of dopamine could reverse the akinesia and improve motor function (Fahn, S., Parkinsonism and Related Disorders The 200-year journey of Parkinson disease: Reflecting on the past and looking towards the future, Parkinsonism Relat. Disord. 46, 1-5 (2017); National Institute for Health and Care Excellence, Parkinson 's Disease in Adults: Diagnosis and Management. NICE Guideline NG71. (2017)).

[0006] The current model of Parkinson's disease focuses on correcting the underlying dopamine deficiency in the midbrain, by providing additional dopamine or reducing its metabolism (National Institute for Health and Care Excellence. Parkinson 's Disease in Adults: Diagnosis and Management. NICE Guideline NG71. (2017) as well as by providing stimulation to the brain regions (electrically) that can stimulate these neural circuits to help relieve the movement disorder of Parkinson's disease (Bronstein et al., Deep brain stimulation for Parkinson disease an expert consensus and review of key issues, Arch. Neurol. 68, 165-171 (2011)). In addition, therapies focus on related complications, such as depression, fatigue, sleepiness, impulse disorders and loss of cognitive function, amongst others.

[0007] Thus the standard of care for Parkinson's - as recently summarized by the United Kingdom's NICE Treatment Guidelines - focused on providing dopaminergic support in the central nervous system, either by supplying dopamine or reducing its metabolic breakdown (National Institute for Health and Care Excellence. Parkinson 's Disease in Adults: Diagnosis and Management. NICE Guideline NG71. (2017) Clinical trials demonstrate such approaches are associated with improved motor function and independence in activities of daily living, though no clinical data show that any such therapy changes the underlying issues, natural history of, or the overall progression of the disease. In fact, these studies show that additional dopaminergic support for patients with Parkinson's disease may only be palliative (The Parkinson Study Group, Levodopa and the Progression of Parkinson's Disease, N. Engl. J. Med. 351, 2498-2508 (2004)). In parallel, the data show that whether patients are untreated or treated with standard of care, neurologic dysfunction progresses to cognitive impairment, psychiatric disorders and other systemic manifestations (National Institute for Health and Care Excellence. Parkinson 's Disease in Adults: Diagnosis and Management. NICE Guideline NG71. (2017)).

[0008] Preclinical data show that dopamine is toxic to dopaminergic neurons, and that reduction of its synthesis protects these cells from dysfunction and death. A novel approach is proposed herein, drug uses to reduce cellular dopamine production to protect neurons, and potentially restore proper dopamine control systems.

[0009] A publication by L. F. Burbulla et al. (Dopamine oxidation mediates mitochondrial and lysosomal dysfunction in Parkinson's disease, Science 357(6357), 2017, 1255-1261) describes a study of dopaminergic neurons derived from patients with idiopathic and familial PD and identifies a time-dependent pathological cascade beginning with mitochondrial oxidant stress leading to oxidized dopamine accumulation and ultimately resulting in reduced glucocerebrosidase enzymatic activity, lysosomal dysfunction, and α-synuclein accumulation.SUMMARY OF THE INVENTION

[0010] In accordance with the present invention, compositions for use are provided that are effective in treating Parkinson's Disease and / or Parkinsonism. These compositions are easily administered by different routes including oral and can be given in dosages as defined in the claims that are safe and provide antagonistic behavior and / or effects to inhibit the production or uptake of dopamine.

[0011] This invention also relates to a correlation between a reduction in dopaminergic cells of the substantia nigra (TH +< cells) and tissue dopamine.

[0012] In one embodiment, Parkinson's Disease and / or Parkinsonism are treated using small molecules as defined in the claims administered systemically that penetrate into the central nervous system to inhibit the rate-limiting step of dopamine synthesis in the central nervous system, the conversion of L-tyrosine to L-3,4-dihydroxyphenylalanine (L-DOPA) by tyrosine hydroxylase along with its cofactors tetrahydrobiopterin and iron (Fe +< ).

[0013] Antagonism of tyrosine hydroxylase decreases levels of aminergic neurotransmitters, such as norepinephrine, epinephrine, and dopamine. One such tyrosine hydroxylase antagonist is metyrosine (U.S. Patent No, 4,1 17,161, U.S. Patent No. 2,868,818, Sjoerdsma, A. et al., Inhibition of Catecholamine Synthesis in Man with Alpha-Methyl-Tyrosine, and

[0014] Inhibitor of Tyrosine Hydroxylase, The Lancet 286, 1092-1094 (1965), Engelman, K. et al., Metabolism of alpha-methyltyrosine in man: relationship to its potency as an inhibitor of catecholamine biosynthesis, J. Clin. Invest. 47, 568-576 (1968)). This and other compounds for use taught herein are synthesized and used in native form(s) as well as with deuterium substituting for hydrogen in one or more locations. To optimize patient compliance, many medicines are packaged in forms that delay the release of the active entity after oral administration.

[0015] In the present invention, a tyrosine hydroxylase inhibitor as defined in the claims is administered as a treatment for Parkinson's disease and / or Parkinsonism.

[0016] In the present invention, a tyrosine hydroxylase inhibitor as defined in the claims is administered as treatment of Parkinson's disease and / or Parkinsonism initially at a nominal dose that is gradually increased over days or weeks.

[0017] In some embodiments of the present invention, administration of a tyrosine hydroxylase inhibitor as defined in the claims is administered as treatment of Parkinson's disease and / or Parkinsonism and supported by concomitant or intermittent administration of dopamine agonist therapy / therapies.

[0018] In some embodiments of the present invention, a tyrosine hydroxylase inhibitor as defined in the claims is administered with an inhibitor of tetrahydrobiopterin biosynthesis as treatment of Parkinson's disease and / or Parkinsonism.

[0019] In some embodiments of the present invention, a tyrosine hydroxylase inhibitor as defined in the claims is administered with an inhibitor of tetrahydrobiopterin biosynthesis as treatment of Parkinson's disease and / or Parkinsonism and supported by concomitant or intermittent administration of dopamine agonist therapy / therapies.

[0020] In some embodiments of the present invention, a tyrosine hydroxylase inhibitor as defined in the claims is administered with an inhibitor of tetrahydrobiopterin biosynthesis as treatment of Parkinson's disease and / or Parkinsonism and supported by concomitant or intermittent administration of VMAT2 inhibitor(s). In some embodiments of the present invention, each of these therapeutic molecules has one or more hydrogen atoms replaced with deuterium, strengthening the bond, slowing metabolism and improving pharmacokinetics and pharmacodynamics.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1. Catecholamine biosynthesis from tyrosine (5) to L-dopa (9) via tyrosine hydroxylase (7), also known as aromatic amino acid hydroxylase, the rate-limiting step, and then to dopamine (13) via aromatic acid decarboxylase (11). Figure 2. Neurotransmission via dopaminergic pathway, from the pre-synaptic axon terminal (60) to the post-synaptic dendrite (62). Major synthetic, metabolic and feedback control mechanisms are represented. Figure 3. Examples of chemicals used for direct inhibition of tyrosine hydroxylase, in Fig. 3(a) AMPT shown with a representative conjugate, the methyl ester form, in Fig. 3(b) alternative tyrosine hydroxylase inhibitors and in Fig. 3(c) template for side chain modification of the amino acid tyrosine hydroxylase inhibitors tyrosine and phenylalanine. For each and other embodiments taught herein, the R3 and R5 moieties undergo substitution with halides, either at R3 or at both locations, which increases potency as a tyrosine hydroxylase inhibitor. Methylation at R0 increases potency. Substitutions by halides at R3 or R3 with R5 to form dihalides as defined in the claims are additional embodiments of the invention. Figure 4. Primary human metabolic pathway of alpha-methyl-p-tyrosine with exemplary deuteration sites. Figure 5. Effect of chronic inhibition of dopamine synthesis with AMPT in dopaminergic iPS cells originating from DJ-l homozygous Parkinson's patients treated with AMPT showing reduced oxidative stress, lower levels of oxidized dopamine, and blunted deposition of a-synuclein. DETAILED DESCRIPTION

[0022] A biochemical hallmark of Parkinson's disease is loss of dopamine in the basal ganglia, particularly with loss of the dopaminergic neuronal cell bodies in the substantia nigra pars compacta (SNpc) (Damier, P. et al., The substantia nigra of the human brain: II. Patterns of loss of dopamine-containing neurons in Parkinson's disease, Brain 122, 1437-1448 (1999), Hirsch, E. et al., Melanized dopaminergic neurons are differentially susceptible to degeneration in Parkinson's disease, Nature 334, 345-348 (1988)). While symptomatic benefit results from administration of dopamine and dopaminergic therapies, such approaches do not appear to change the course of disease (The Parkinson Study Group, Levodopa and the Progression of Parkinson's Disease, N. Engl. . / . Med. 351, 2498-2508 (2004)). As depicted in Figure 2, dopaminergic neurotransmission from pre- to post-synaptic terminal is controlled on several levels. Pre-synaptic dopamine synthesis is controlled via effects on biopterin dependent enzyme tyrosine hydroxylase (50) conversion of tyrosine (20) to L-dopa (22). Dopamine (24) in the cytosol is sequestered within vesicles (26) based on VMAT2 activity, which prevents cellular toxicity. Upon stimulation, via membrane depolarization, vesicles fuse with the cell membrane (28) and dopamine is released into the synapse (30) via exocytosis. In addition to stimulating the post-synaptic membrane at D1 (32) and D2 (34) receptors, pre-synaptic D2 (38) receptors serve auto-regulatory function. The high levels of dopamine in the cleft result in rapid reuptake by the pre-synaptic terminal via DAT channels (36), with that dopamine stored once again in vesicles driven by VMAT2 activity, and free cytosolic dopamine (42) metabolized via MAO-B and COMT enzymes (44).

[0023] D1 and D2 receptors are G-protein coupled protein receptors (GCPR), with post-synaptic D1 (32) and D2 (34) receptors having opposing effects on dendritic cAMP (58) activity. D1 stimulation increases cAMP (58) via the stimulatory G protein coupled Gsadenyl cyclase complex (54), and thereby intracellular calcium, while D2 stimulation reduces cAMP (58) via the inhibitory G protein coupled Gi-adenyl cyclase complex (56).

[0024] In a state of excess dopaminergic drive starting at the axon terminal, a deficit in VMAT2 driven vesicular storage exposes the axon to toxic free radicals formed from breakdown of cytosolic dopamine. The protein α-synuclein (40) is known to be the major component of intracellular Lewy Bodies, which serve as markers of disease progression as well as impairing neuronal function. In addition, α-synuclein appears to play several roles in mitigation of the risk of dopamine toxicity within the axon terminal, including (a) inhibition of tyrosine hydroxylase (50) and amino acid decarboxylase (52), (b) stimulating formation of vesicles for dopamine storage (26) and reducing the rate of DAT-mediated dopamine reuptake (36). α-synuclein also spares dendritic exposure to dopamine, as it blunts vesicular exocytosis of dopamine (28). In addition, binding between α-synuclein and free cytosolic dopamine leads to reduced cellular exposure to dopaminergic free radicals, though at the cost of protofibril formation that hastens the development of Lewy Bodies. These mechanistic phenomena suggest that Lewy Body formation may represent protective neuronal mechanisms for brief exposure to toxic dopamine that result in additional pathologic effects when the mechanism remains active long-term.

[0025] VMAT2 deficiency whether due to genetic abnormality or altered gene expression further exposes the neuron and its axon to dopamine toxicity. When dopamine is stored within the axonal vesicles, as it would be prior to exocytosis into the intrasynaptic cleft, it is protected against oxidation. And that oxidation of dopamine is a major trigger leading to neuronal toxicity. As described below, while total dopamine is markedly depleted, the per cell amount of dopamine is near normal in Parkinson's disease. Thus, the VMAT2 deficiency of Parkinson's means that the balance between vesicular and cytosolic dopamine shifts towards super-normal cytosolic dopamine content, amplifying the amount of oxidized dopamine and the risk of cellular and organelle (e.g., mitochondrial) dysfunction and death from this toxic form of dopamine (Lohr, K. M. & Miller, G. W., VMAT2 and Parkinson's disease: harnessing the dopamine vesicle, Expert Rev. Neurother. 14, 1115-1 117 (2014)).

[0026] The complexity and risk from these control mechanisms are underscored by recognition that the polymers deposited in mitochondrial impair energy production, further amplifying oxidative stress. Directly and / or indirectly, alpha-synuclein impairs neuronal function and increases likelihood of cell death.

[0027] To date, the precise trigger(s) for the development of sporadic Parkinson's Disease is(are) unknown, though several genetic forms lead to similar pathology, with dopamine associated toxicity along with reduced dopamine stores resulting from loss of dopaminergic neurons. Thus, the genetic forms also are treated as a dopamine deficiency state that must be reversed. This invention teaches a novel use for treating Parkinson's disease in both subclinical and clinical states, reducing dopamine production and / or increasing its metabolism within viable neurons.

[0028] Disclosed herein are compounds for use for reducing dopamine in the neurons of the central nervous system, in particular for neurons within the substantia nigra pars compacta, as a treatment for patients with Parkinson's Disease, including those identified with neurochemical abnormalities that would be expected to evolve into overt Parkinson's Disease, whether early or late in disease evolution, to slow, reverse and / or halt disease progression.

[0029] Based on metabolism of dopamine, the approaches could include any or all of the following: antagonism of tyrosine hydroxylase activity, antagonism of amino acid decarboxylase, stimulation of monoamine oxidase type B activity and / or stimulation of catechol-O-methyltransferase activity. Because the amino acid decarboxylase relevant to Parkinson's disease and / or Parkinsonism - dopamine decarboxylase - is not rate limiting in dopamine synthesis, this is not a focus of this invention. Therefore, taught herein are compounds for use that antagonize tyrosine hydroxylase, using direct enzymatic inhibitors as well as using direct inhibitors of its required co-factor, tetrahydrobiopterin.

[0030] While total dopamine amounts are depleted, on a per cell basis Parkinson's disease patients appear to maintain normal amounts of dopamine synthesis. However, neurons cannot protect themselves from dopamine toxicity even at these normal physiologic levels, and therefore, would appear to be at heightened risk of toxicity from the pharmacologic levels produced by medicines (Meiser et al., Complexity of dopamine metabolism. Cell Commun. Signal. 11, 1-18 (2013), Moon, H. E. & Paek, S. H. Mitochondrial Dysfunction in Parkinson's Disease, Exp. Neurobiol. 24, 103-16 (2015)). With increase amount of alpha-synuclein, Parkinson's neurons can no longer protect themselves from dopamine toxicity by sequestering it within intracellular vesicles (Perez, R. G. et al., A role for α-Synuclein in the Regulation of Dopamine Biosynthesis, J Neurosci. 22, 3090-3099 (2002), Venda et al., a - Synuclein and dopamine at the crossroads of Parkinson's disease, Trends Neurosci. 33, 559-568 (2010)). And because they suffer from mitochondrial dysfunction, the cells are exposed to oxidative stress (free radical generation) that impairs cellular function (Moon, H. E. & Paek, S. EL, Mitochondrial Dysfunction in Parkinson's Disease, Exp. Neurobiol. 24, 103-16 (2015)). In the presence of dopamine, this oxidative stress results in formation of alpha-synuclein protofibrils (Conway, K. A., Kinetic Stabilization of the alpha-Synuclein Protofibril by a Dopamine-alpha-Synuclein Adduct, Science 294, 1346-1349 (2001)). Formation of Lewy Bodies further impairs cellular function (Perez, R. G. et al, A role for α-Synuclein in the Regulation of Dopamine Biosynthesis, J. Neurosci. 22, 3090-3099 (2002), Venda et al., α-Synuclein and dopamine at the crossroads of Parkinson's disease, Trends Neurosci. 33, 559-568 (2010)). Pharmacologic treatment of Huntington's inhibits VMAT2, which reduces the capacity to store dopamine within vesicles and similar to in Parkinson's, results in a relative excess of dopamine in the neurons. These factors contribute to cell death (Ogawa et al., L-DOPA treatment from the viewpoint of neuroprotection: Possible mechanism of specific and progressive dopaminergic neuronal death in Parkinson's disease, J. Neurol. 252, 23-31 (2005)).

[0031] Tyrosine hydroxylase, with its four isoforms, is the rate limiting enzyme in the synthesis of dopamine in the central nervous system (Meiser et al., Complexity of dopamine metabolism, Cell Commun. Signal. 11, 1-18 (2013), Levitt, et al., Elucidation of the Rate-Limiting Step in Norepinephrine Biosynthesis in the Perfused Guinea-Pig Heart, J. Pharmacol. Exp. Ther. 148, 1-8 (1965)), working with its cofactor tetrahydrobiopterin. In one embodiment, the composition for use in treating Parkinson's Disease and / or Parkinsonism includes the tyrosine hydroxylase inhibitor metyrosine (Demser ®< , manufactured as the L-enantiomer), also known as alpha-methyl-p-tyrosine (AMPT). In another embodiment, the composition for use in treating Parkinson's Disease and / or Parkinsonism includes a racemic mixture of alpha-methyl-p-tyrosine.

[0032] In another embodiment, due to risk of nephrolithiasis during AMPT use, a combination of AMPT with a urinary alkalinizing agent is administered.

[0033] AMPT antagonizes tyrosine hydroxylase (Sjoerdsma et al., Inhibition of Catecholamine Synthesis in Man with Alpha-Methyl-Tyrosine, and Inhibitor of Tyrosine Hydroxylase, The Lancet 286, 1092-1094 (1965), Engelman et al., Metabolism of alpha-methyltyrosine in man: relationship to its potency as an inhibitor of catecholamine biosynthesis, J. Clin. Invest. 47, 568-576 (1968), Nagatsu et al., Tyrosine Hydroxylase: The Initial Step in Norepinephrine Biosynthesis, J. Biol. Chem. 239, 2910-2917 (1964), Udenfriend et al., Inhibitors of Purified Beef Adrenal Tyrosine Hydroxylase, Biochem Pharmacol 14, 837-845 (1965)). An AMPT concentration of 10 -4< M inhibits tyrosine hydroxylase by 86% in guinea pig brain particle preparations and by 50% at concentrations of 2.5xl0 -5< M in bovine adrenal gland preparations (Nagatsu et al., Tyrosine Hydroxylase: The Initial Step in Norepinephrine Biosynthesis, J. Biol. Chem. 239, 2910-2917 (1964), Udenfriend et al., Inhibitors of Purified Beef Adrenal Tyrosine Hydroxylase, Biochem Pharmacol 14, 837-845 (1965)). Various additional dosage forms and concentrations of AMPT are also effective, ranging between 500-2500 mg / day. partially encompassed

[0034] Additional compounds by the appended claims represent other aspects of this disclosure (or in part embodiments of the invention) taught, based on data that establish their potency as inhibitors of tyrosine hydroxylase.

[0035] Each of these listed compounds in Tables 1A and 1B (shown below) are amino acid analogs or catecholamine analogs inhibiting tyrosine hydroxylase. (See, Nagatsu et al., Tyrosine Hydroxylase: The Initial Step in Norepinephrine Biosynthesis, J Biol. Chem. 239, 2910-2917 (1964), Udenfriend et al., Inhibitors of Purified Beef Adrenal Tyrosine Hydroxylase, Biochem Pharmacol 14, 837-845 (1965)). Table 1A: Amino acid analogs inhibiting tyrosine hydroxylaseCompoundConcentration for 50% Inhibition (M)Concentration (M)%InhibitionL-tryptophan>1x10 -3< 10 -4< 50D-tryptophan10 -4< 0L-phenylalanine2x10 -4< 10 -4< 78D-phenylalanine>1x10 -3< 10 -4< 7DL-p-fluoro-phenylalanine10 -4< 613-iodo-L-tyrosine5x10 -7< 3-chloro-L-tyrosine1x10 -5< 3-fluoro-DL-tyrosine1x10 -3< 3,5-diiodo-L-tyrosine2x10 -5< 3,5-dibromo -L-tyrosine5x10 -4< α-methyl-L-tyrosine2.5x10 -5< 10 -4< 86α-methyl-D-tyrosine>1x10 -3< α-methyl-m-DL-tyrosine>1x10 -3< 2x10-492α-methyl-DL-phenylalanine8x10 -5< 3-iodo-α-methyl-DL-tyrosine3x10 -7< 3-bromo-α-methyl-DL-tyrosine1.5x10 -6< 3-chloro-α-methyl-DL-tyrosine5x10 -6< 3-fluoro-α-methyl-DL-tyrosine2x10 -4< 3-chloro-4-methoxy-α-methyl-DL-phenylalanine5x10 -4< Table 1B: Catecholamine analogs inhibiting tyrosine hydroxylase CompoundConcentration for 50% Inhibition (M)Concentration (M)%Inhibitiondopamine10 -4< 56L-norepinephrine1x10 -3< DL-norepinephrine2 x 10 -4< 53L-dopa10 -4< 68D-dopa10 -4< 0L-epinephrine10 -4< 35D-epinephrine10 -4< 473,4-dihydroxyphenyl-acetamide1x10 -3< 3,4-dihydroxyphenyl-propyl-acetamide (H-22 / 54)2x10 -5< 10 -4< 843,4-hydroxy-L-phenylalanine2x10 -3< 3,4-hydroxy-D-phenylalanine>4x10 -3< α-methyl-3,4-dhydroxy-L-phenylalanine (Aldomet)1.5x10 -3< α-methyl-3,4-dhydroxy-D-phenylalanine>8x10 -3<

[0036] Amino acid derivatives also act as tyrosine hydroxylase inhibitors (Udenfriend et al., Inhibitors of Purified Beef Adrenal Tyrosine Hydroxylase, Biochem Pharmacol 14, 837-845 (1965)). For example, most analogs of phenylalanine and tyrosine inhibit tyrosine hydroxylase, including racemic or L-amino acid in particular. Additional potency results from α-methylation. Substitution at the 3-position of the benzene ring of claimed amino acids with a halogen atom adds potency, and such compounds are taught herein as additional embodiments. Substitution at both the 3 and 5 positions with halogen atoms are taught herein as additional embodiments of this invention.

[0037] Hoffman describes several families of tyrosine hydroxylase inhibitors, though in the setting of cancer and not neurologic therapeutics (U.S. Patent Publication No. 2017 / 0056371). These compounds include: one or more of methyl (2R)-2-amino-3-(2-chloro-4 hydroxyphenyl) propanoate, D-tyrosine ethyl ester hydrochloride, methyl (2R)-2-amino-3-(2,6-dichloro-3,4-dimethoxyphenyl) propanoate H-D-Tyr(TBU)-allyl ester HC1, methyl (2R)-2-amino-3-(3-chloro-4,5-dimethoxyphenyl) propanoate, methyl (2R)-2-amino-3-(2-chloro-3 -hydroxy -4-methoxyphenyl) propanoate, methyl (2R)-2-amino-3-(4-[(2-chloro-6-fluorophenyl)methoxy]phenyl) propanoate, methyl (2R)-2-amino-3-(2-chloro-3,4-dimethoxyphenyl) propanoate, methyl (2R)-2-amino-3-(3-chloro-5-fluoro-4-hydroxyphenyl) propanoate, diethyl 2-(acetylamino)-2-(4-[(2-chloro-6-fluorobenzyl) oxyjbenzyl malonate, methyl (2R)-2-amino-3-(3-chloro-4-methoxyphenyl) propanoate, methyl (2R)-2-amino-3-(3-chloro-4-hydroxy-5-methoxyphenyl) propanoate, methyl (2R)-2-amino-3-(2,6-dichloro-3-hydroxy-4-methoxyphenyl) propanoate, methyl (2R)-2-amino-3-(3-chloro-4-hydroxyphenyl) propanoate, H-DL-tyr-OME HC1, El-3,5-diiodo-tyr-OME HC1, H-D-3,5-diiodo-tyr-OME HC1, H-D-tyr-OME HC1, D-tyrosine methyl ester hydrochloride, D-tyrosine-ome HC1, methyl D-tyrosinate hydrochloride, H-D-tyr-OMe-HCl, D-tyrosine methyl ester HC1, H-D-Tyr-OMe-HCl, (2R)-2-amino-3-(4-hydroxyphenyl) propionic acid, (2R)-2-amino-3-(4-hydroxyphenyl) methyl ester hydrochloride, methyl (2R)-2-amino-3-(4-hydroxyphenyl) propanoate hydrochloride, methyl (2R)-2-azanyl-3-(4-hydroxyphenyl) propanoate hydrochloride, 3-chloro-L-tyrosine, 3-nitro-L-tyrosine, 3-nitro-L-tyrosine ethyl ester hydrochloride, DL-m-tyrosine, DL-o-tyrosine, Boc-Tyr (3,5-I2)-oSu, Fmoc-tyr(3-N0 2 )-0H, α-methyl-L-tyrosine, a-methyl-D-tyrosine, and a-methyl-DL-tyrosine. Taught herein are dose ranges from 1 µg to 25 g per day for each of these compounds.

[0038] Additional tyrosine hydroxylase inhibitors Table) 2 (not part of the claimed invention). Table 2: Tyrosine hydroxylase inhibitors.ChemicalFormulaMolar MassHighest Prior DoseMax Dose Herein3-iodotyrosine 1< C 9 H 10 INO 3 307.09 g / mol--bulbocapnineC 19 H 19 NO 4 325.36 g / mol~ 200 mg / d2 mg / daquayamycin 2< C 25 H 26 O 10 486.47 g / mol-60 mg / doudenoneC 12 H 16 O 3 208.25 g / mol~ 1 g / d10 g / d1: 3-Iodotyrosine is an intermediate in the synthesis of thyroid hormones and its effects systemically preclude its delivery in this manner for the intended central nervous system effect. 2: The LD 50 in mice is reported at a dose as low as 12.5 mg / kg, the human equivalent of 1 mg / kg in 60 kg adult, which is therefore expected to be the maximum dose for this invention.

[0039] Oudenone is a pentene based molecule identified from a needle-leaf tree demonstrated to inhibit tyrosine hydroxylase when directly measured, and also reduce blood pressure in spontaneously hypertensive rats (Umezawa, H. et al. A New Microbial Product, Oudenone, Inhibiting Tyrosine Hydroxylase, J. Antibiot. (Tokyo) 23, 514-518 (1970)). These investigators prepared sodium, potassium, calcium, magnesium and barium salts. quayamycin can be use as a tyrosine hydroxylase inhibitor, with potency near that reported for 3-iodo-a-methyl-DL-tyrosine (Udenfriend et al., Inhibitors of Purified Beef Adrenal Tyrosine Hydroxylase, Biochem Pharmacol 14, 837-845 (1965), Ayukawa, S. et al. Inhibition of Tyrosine Hydroxylase by Aquayamycin, J. Antibiot. (Tokyo) 21, 350-353 (1968)). Taught herein are dose ranges from 1 µg to 25 g per day for each of these compounds. Also described herein, but not encompassed by the claims is impairment of biosynthesis of tetrahydrobiopterin via sulfa compounds that cross the blood-brain-barrier, requisite for affecting tyrosine hydroxylase catalyzed dopamine production. Examples include sulfathiazole, sulfamethoxazole, sulfadiazine, sulfapyridine and sulfamethazine, each of which inhibits sepiapterin reductase, which catalyzes the final step in tetrahydrobiopterin synthesis, with IC50 values below 100 nM (Haruki et al., Tetrahydrobiopterin biosynthesis as an off-target of sulfa drugs, Science 340, 987-991 (2013)).

[0040] Examples are provided in Table 3, where for each, one example is to start at low dose and titrate up to target or maximally tolerated dose, as exemplified for alpha-methyl-p-tyrosine in Table 4. Table 3 : Examples of tyrosine hydroxylase inhibitors with maximum daily doses to be usedChemicalHighest Prior DoseMax Dose Hereinsulfathiazole 1< 1.5 gm / d1.5gm / dsulfamethoxazole1.6 gm / d16 gm / dsulfadiazine4 g / day40 g / daysulfapyridine 2< 16 g / day (sulfasalazine)160 g / d (sulfasalazine)sulfamethazine 3< only used in large animals-1: Sulfathiazole is not administered at dose higher than previously used as any higher produces unacceptable side effect profile. 2: Sulfapyridine human exposure results from metabolism of sulfasalazine, which is given at doses up to 16 g / day. 3: Sulfamethazine is only used in animals with max dose of 250 mg / kg, the equivalent of approximately 17 kg / day, indicating this compound is not viable as human therapeutic. Table 4: alpha-methyl-p-tyrosine dosing schedule VisitDosing (mg)Daily Dose (mq)Week 1:25 / 2550Week 2:50 / 50100Week 3:100 / 100200Week 4:100 / 100 / 100300Week 5:150 / 150 / 150450Week 6:200 / 200 / 200600Week 7:250 / 250 / 250750Week 8:300 / 300 / 300900Week 9:400 / 400 / 4001200Week 10:500 / 500 / 5001500

[0041] One of the effects of methotrexate is inhibition of dihydropteridine reductase (DHPR), an enzyme critical for formation of tetrahydrobiopterin, the cofactor required for tyrosine hydroxylase inhibition. Thus methotrexate can be used to inhibit tyrosine hydroxylase activity indirectly. For the sulfa compounds, dosing starts as recommended in approved labeling from the U.S. Food and Drug Administration, with maximum doses an order of magnitude higher than specified for primary indications and / or prior pharmacology studies, with limitations noted in Tables 2 and 3.

[0042] Alpha-methyl-p-tyrosine can be dosed between 5 mg a day up to 2000 mg per day. Taught herein is a use in a method of initiating therapy at low doses that are gradually increased, over days, weeks or months.

[0043] In one embodiment, doses start at a range of 1 mg daily up to 250 mg daily would be the starting dose, and target dose would range from 100 mg daily to 1000 grams daily. Table 4 is merely one example of how a dose titration is completed, in this case of a patient started at 50 mg daily and titrated to 1500 mg daily.

[0044] In another embodiment, doses start at frequencies of administration less than four times daily, including formulations up to once monthly via depo methods, where depo refers to pharmaceutical method of injecting or implanting a therapeutic agent into a tissue where it is absorbed more slowly for prolonged maintenance of therapeutic drug levels in the body. In another embodiment, the amount of each dose is increased and in another embodiment, the frequency of doses is increased, in order to increase the total daily dosage.

[0045] In another embodiment, the amount of each dose and the frequency of dosing are both used to increase the total daily drug dose. One of the ways to explain this embodiment is shown in Table 4, using alpha-methyl-p-tyrosine as the example, provided to show only one representation of a dose titration schedule and one example of a tyrosine hydroxylase antagonist. Other tyrosine hydroxylase antagonists and doses would be known to a person of ordinary skill in the art.

[0046] In another embodiment, the tyrosine hydroxylase inhibitor is administered using this graduated dosing approach while continuing the background therapy including dopaminergic medicines, including but not limited to levodopa-containing agents, MAO-B inhibitors and / or COMT inhibitors, as well as dopamine agonists. For this embodiment, the dose(s) of the background medicine(s) are gradually reduced while the tyrosine hydroxylase inhibitor dose is increased or while the dose of tyrosine hydroxylase inhibitor is held constant.

[0047] In another embodiment, the standard dopaminergic therapies are discontinued prior to initiation of therapy with tyrosine hydroxylase inhibition.

[0048] In another embodiment, the standard dopaminergic therapies are introduced as clinically required to help the patient(s) tolerate the increase in the dose of tyrosine hydroxylase inhibitor.

[0049] In another embodiment, the standard dopaminergic therapies are re-introduced or the dose(s) augmented as required to stabilize patient(s) clinically during the introduction and dose-titration of the tyrosine hydroxylase inhibitor(s) for a finite period of time.

[0050] In another embodiment, the use of deep brain stimulation is reduced to the minimum required for clinical stability, with the stimulation used more or less as clinically indicated, and in some embodiments, withdrawn (even if not explanted).

[0051] The tyrosine hydroxylase and / or tetrahydrobiopterin inhibitor(s) is(are) manufactured in modified release formulation(s) to reduce dosing frequency and / or control drug levels.

[0052] Diffusion systems may be used, including use of polymer coatings that reduce the rate of dissolution following ingestion.

[0053] For example, active drugs are dissolved in a gelling agent.

[0054] For example, active drug(s) are administered in tablet(s) coated with semipermeable membrane or laser-drilled holes, through either of which drug release follows the absorption of water while passing through the gastrointestinal system. Active drug(s) may also be manufactured within a matrix composed of polymers or lipids with delayed erosion by digestive enzymes.

[0055] For example, active drug(s) are manufactured as liquids or liquid suspensions and administered intra-nasally, with starting doses then as low as 1 / 10 to 1 / 1,000 of those listed herein.

[0056] In some embodiments, the tyrosine hydroxylase inhibitor is administered as its salt, ester, acid, gluconate, carbonate, anhydrous or free base forms.

[0057] In one such test, Parkinson's patients will be treated with one or more, in combination of succession, of the compounds taught herein for this use. Such a clinical trial will include both those patients early in the disease, not yet treated with pharmacologic stimulators of dopamine, as well as those already receiving such agents. Regulators may request such studies to be conducted separately on each population.

[0058] In such or any other clinical trials, standard measures of clinical status may be used to assess outcome, such as the Unified Parkinson's Disease Rating Scale. Functional tests evaluating ambulation are also useful outcomes for measurement, such as the 6 minute walk test, timed up and go test, and the like. Imaging of brain function, such as via PET or SPECT scanning, and the like, are used for understanding mechanisms of drug effect, and may be used in clinical testing. Other such functional tests would be known to a person of ordinary skill in the art.

[0059] In Parkinson's disease, treatment to increase dopaminergic levels is associated with adverse effects exemplified by tardive dyskinesia. This is often associated with peak drug levels. In the same patient(s), as the dopamine and / or drug levels wane, the tardive dyskinesia is replaced by akinesia or bradykinesia, referred to as "off periods." A focus of drug developers is levodopa-based therapies that produce more favorable pharmacokinetics to reduce these swings, as well as permit less frequent dosing.

[0060] Taught herein is deuteration of the therapies. Timmins and others teach how deuterium's heavier molecular weight increases the strength of its bonds compared to hydrogen atom(s). With that greater strength comes slower metabolism, longer half-life and less variability in drug levels (Timmins, G. S. HHS Public Access, Expert Opin Ther Pat 24(10), 1067-1075 (2014), Gant, T. G. & Shahbaz, M. M., Benzoquinoline Inhibitors of Vesicular Monoamine Transporter 2. (2013), (73), Sommer, A. et al., Formulations Pharmacokinetics of Deuterated Benzoquinoline Inhibitors of Vesicular Monoamine Transporter 2. (2016)). Such changes in pharmacokinetics are advantageous in clinical practice and taught herein for Parkinson's treated with tyrosine hydroxylase inhibition.

[0061] The method of deuteration is taught herein, using AMPT as an example, with its metabolic pathway shown in Figure 4. Examples of deuteration target(s) for alpha-methyl-p-tyrosine (AMPT), shown as the metabolic pathway of AMPT in humans. Each R represents the site of a hydrogen atom in non-deuterated state, as well as a site for deuteration to inhibit the rate of metabolism from one step to the next. 200: alpha-methyl-p-tyrosine (AMPT), 210: alpha-methyl-dopa (AMD), 220): alpha-methyl-dopamine (AMD A), 230: alpha-methyl-norepinephrine (AMNE). AMPT (200) is metabolized to alpha-methyl-dopa (210) then to alpha-methyl-dopamine (220) and finally to alpha-methyl-norepinephrine (230) (Engelman et al., Metabolism of alpha-methyltyrosine in man: relationship to its potency as an inhibitor of catecholamine biosynthesis, J. Clin. Invest. 47, 568-576 (1968), Brogden et al., alpha-Methyl-p-Tyrosine: A Review of its Pharmacology and Clinical ETse, Drugs 21, 81-89 (1981)). Delivered orally, the drug is well absorbed (-69%) (Brogden et al., alpha-Methyl-p-Tyrosine: A Review of its Pharmacology and Clinical ETse, Drugs 21, 81-89 (1981)) and relatively little of these metabolites are recovered in the urine. Trace amounts of each can be detected (Engelman et al., Metabolism of alpha-methyltyrosine in man: relationship to its potency as an inhibitor of catecholamine biosynthesis, J. Clin. Invest. 47, 568-576 (1968)).

[0062] In Figure 4, locations for deuteration are indicated by R n , which are occupied by hydrogen atoms in native state. Taught herein is substitution at one or more of the R n locations with a deuterium atom in place of a hydrogen atom. Deuteration results in stronger bonds and therefore slower reactions at that / those bond(s). Included is substation at R 5 in alpha-methyl-norepinephrine, as dehydroxylation at OR 5 produces trace amounts of alpha-methyl-tyramine.

[0063] Because Parkinson's and Parkinsonism feature presynaptic axonal cytosolic dopamine levels that are neurotoxic, whether the cause is due to one or more of the known or unknown genetic causes, or the disease is idiopathic in etiology, the therapeutics taught herein are applicable to genetic or non-genetic causes, including as examples GBA, LRRK2, SNCA, VPS35, Parkin, PINK1, and DJ1.

[0064] A person of ordinary skill in the art would understand that modifications and substitutions could be made to the invention disclosed herein, as relates to the compounds, and means for measuring the clinical effects, but only to the extent as these modifications are within the scope of the claims.

Claims

1. A composition for use in treating Parkinson's disease and / or Parkinsonism, wherein the composition comprises one or more inhibitor of tyrosine hydroxylase, wherein the inhibitor of tyrosine hydroxylase includes a) alpha-methyl-p-tyrosine, b) alpha-methyl-p-tyrosine, wherein the alpha-methyl-p-tyrosine is deuterated in one or more positions where metabolism of alpha-methyl-p-tyrosine involves hydroxylation and / or carbonylation, c) alpha-methyl-p-tyrosine, wherein the 3' and / or 5' position of the benzene ring of the alpha-methyl-p-tyrosine is substituted with a halide, optionally wherein the halide form of alpha-methyl-p-tyrosine is deuterated in one or more positions where metabolism of alpha-methyl-p-tyrosine involves hydroxylation and / or carbonylation, and / or d) alpha-methyl-p-tyrosine, wherein the alpha-methyl-p-tyrosine is methyl substituted, optionally wherein the methyl substituted form of alpha-methyl-p-tyrosine is deuterated in one or more positions where metabolism of alpha-methyl-p-tyrosine involves hydroxylation and / or carbonylation, and wherein the alpha-methyl-p-tyrosine is administered at a nominal dose that is gradually increased over days or weeks.

2. The composition for the use according to claim 1, wherein alpha-methyl-p-tyrosine is administered in a dose of 1 µg to 25 g per day, or from 500 mg to 2500 mg per day.

3. The composition for the use according to claim 1, wherein the cause of Parkinsonism is progressive supranuclear palsy, multiple system atrophy, diffuse Lewy Body disease, drug-induced Parkinsonism, Creutzfeldt-Jakob disease or chronic brain trauma.

4. The composition for the use according to claim 1, wherein Parkinson's disease is based on one or more genetic causes selected from GBA, LRRK2, SNCA, VPS35, Parkin, PINK1 and / or DJ1.

5. The composition for the use according to claim 1, wherein alpha-methyl-p-tyrosine is administered initially at a dose ranging from 1 mg daily up to 250 mg daily with a target maintenance dose at a range from 100 mg daily to 1000 grams daily.

6. The composition for the use according to claim 1, wherein the composition is administered intra-nasally, and wherein alpha-methyl-p-tyrosine is administered at an initial dose ranging from 0.01 mg daily up to 25 mg daily with a target maintenance dose ranging from 1 mg daily to 100 grams daily.

7. The composition for the use according to claim 1, wherein the composition is administered in conjunction with levodopa, dopaminergic containing medicines, MAO-B inhibitors, COMT inhibitors, or any combination thereof.

8. The composition for the use according to claim 7, wherein the doses of levodopa or dopaminergic containing medication, MAO-B inhibitor and / or COMT inhibitor are adjusted during the initiation and ongoing administration of the composition containing alpha-methyl-p-tyrosine as clinically indicated.

9. The composition for the use according to claim 1, wherein the composition is administered in conjunction with VMAT2 inhibitor(s).

10. The composition for the use according to claim 1, wherein the halide is fluoride, chloride, bromide, and / or iodide.

11. The composition for the use according to claim 1, wherein the composition is administered with a urinary alkalinizing agent selected from the group consisting of sodium bicarbonate, calcium carbonate, sodium citrate, potassium citrate and calcium citrate.

12. The composition for the use according to claim 11, wherein the urinary alkalinizing agent is administrated at a dose ranging from 5 to 300 mEq / day.