Benzisoxazole compound for treatment of KMO mediated disorders

Abstract

The invention relates to a compound for use in a method of treating or preventing a KMO mediated disorder in a subject in need thereof; wherein said compound is a benzisoxazole of formula (I) or a pharmaceutically acceptable salt thereof, wherein said method comprises administering said compound to the subject as an intravenous infusion at a dose rate of between about 200 µg / h and about 2.5 mg / h for a period of at least 12 hours.

Description

[0001] COMPOUND FOR TREATMENT OF KMO MEDIATED DISORDERS

[0002] FIELD OF THE INVENTION

[0003] The invention relates to compounds for use in treatment or prevention of KMO mediated disorders.

[0004] BACKGROUND

[0005] KMO mediated disorders have a significant detrimental effect on the quality of life of patients.

[0006] Kynurenine monooxygenase (KMO) is a flavin adenine dinucleotide (FAD) dependent monooxygenase located on the outer mitochondrial membrane. KMO is known to oxidise L- kynurenine (KYN) to 3 -hydroxykynurenine (3HK) as part of the major route of catabolism of tryptophan. 3HK is then converted to 3-hydroxyanthranilic acid and quinolinic acid by kynureninase (KYNU) and 3 -hydroxy anthranilate 3, 4-di oxygenase (3-HAAO).

[0007] KMO is highly expressed in tissues including the liver, placenta, kidney, endothelial cells and monocytes and at a lower level in microglia and macrophages in the brain.

[0008] Increased levels of 3HK have been implicated in a number of diseases including acute pancreatitis [Skouras, Zheng, Binnie et al. Scientific Reports 2016: 6: 33951] and acute kidney injury [Mole, McFerran et al. British Journal of Surgery 2008: 95: 855-867],

[0009] There is a large body of evidence showing that tryptophan metabolism is also altered in a range of acute injury settings. For instance, increased kynurenine levels have been associated with the development of sepsis following trauma [Pellegrin et al. Shock 2005: 23: 209-215, Logters et al. Shock 2009: 32: 29-34], while increased levels of both kynurenine and 3HK correlate with the development of organ failure in acute pancreatitis [Mole, McFerran et al. British Journal of Surgery 2008: 95: 855-867; Skouras, Zheng, Binnie et al. Scientific Reports 2016: 6: 33951], This dysregulation of tryptophan metabolism is in part accounted for by the induction of indolamine 2,3 dioxygenase (IDO, the enzyme that converts tryptophan to N- formyl kynurenine) as part of the inflammatory cascade, but the development of organ dysfunction appears dependent on the downstream metabolites [Mole, McFerran et al. British Journal of Surgery 2008: 95: 855-867; Mole, Webster et al. Nature Medicine 2016: 22: 202- 209],

[0010] Acute pancreatitis (AP) results from local injury to the organ driven by factors such as excessive alcohol consumption or gallstones. The arising abdominal pain is extremely severe, and patients will invariably present to an emergency department rapidly following onset of an attack, with elevation of serum amylase used as a diagnostic measure. In the majority of cases, the disease is self-limiting, and the pain is resolved within 24-36 hours. However, for the remaining 20-30% of patients a systemic inflammatory response occurs, resulting in rapid progression to multiple organ dysfunction syndrome (MODS). This leads to a prolonged stay in an intensive care unit (ICU), averaging 17 days, with a mortality rate of over 30%. Despite this high unmet need and the seriousness of the disease, there are no effective treatments available, with current standard of care being purely supportive. There are several proposed systems to stratify the severity of AP, including the Revised Atlanta Criteria (RAC) [Banks et al. Gut. 2013: 62: 102-111] and the Determinants-based classification (DBC) [Dellinger et al. Ann Surg. 2012: 256: 875-880], Recent international guidelines state that the RAC is most commonly used in practice [IAP / APA / EPC / IPC / JPS Working Group, Pancreatology. 2025: https: / / doi.Org / 10.1016 / j.pan.2025.04.020], Mild AP is defined as patients with AP who have no additional organ failure, for example respiratory or renal failure, and without local or systemic complications. Moderate severity AP is defined by the presence of transient organ failure, or local complications. Severe AP is defined as those having additional organ failure persisting > 48 h, and these patients often must be treated in an intensive care unit (ICU) [Finkenstedt, et al. Intensive Care Med 2023 : 49: 1127-1130], The DBC further defines patients having critical acute pancreatitis as those having persistent organ failure and infected (peri-)pancreatic necrosis. The severity of acute pancreatitis can be correlated to the level of 3HK in the plasma [Skouras, Zheng, Binnie et al. Scientific Reports 2016: 6: 33951], Acute kidney injury (AKI) is also known in the art to be associated with KMO activity. For example, mice lacking KMO activity can be protected from AKI [Zheng, Zhang et al Experimental & Molecular Medicine 2019: 51 : 1-14],

[0011] Patients with acute pancreatitis are more susceptible to KMO mediated disorders, such as multiple organ failure. Further, patients having recently had major surgery, such as heart surgery, are more susceptible to KMO mediated disorders, such as acute kidney injury.

[0012] Inhibition of KMO oxidative activity would therefore be expected to result in reduced levels of 3HK to potentially show benefit in treating or preventing these disorders.

[0013] Inhibitors of KMO may therefore be useful in the treatment of various conditions or disorders such as, for example, acute pancreatitis, acute kidney injury (AKI) and acute conditions associated with systemic inflammatory response syndrome (SIRS).

[0014] SUMMARY OF THE INVENTION

[0015] The present invention provides methods of treating or preventing a KMO mediated disorder in a human subject and compounds for use in such methods. Administration of such compounds will result in inhibition of KMO. In particular, administering these compounds in an amount which will result in inhibition of KMO and resultant reduction in 3HK production is useful for treatment or prevention of KMO mediated disorders.

[0016] The inventors have surprisingly discovered that administration of such compounds at a given dosage rate as an intravenous infusion results in increased inhibition of KMO and reduced 3HK levels in comparison to what would have been predicted from both preclinical pharmacokinetic data using standard species scaling and single dose administration.

[0017] These findings open up the possibility of treating or preventing KMO mediated disorders by dosing the compounds at levels well below those otherwise predicted. The invention therefore provides a compound for use in a method of treating or preventing a KMO mediated disorder in a human subject in need thereof; wherein said compound is a benzisoxazole of formula (I) or a pharmaceutically acceptable salt thereof: wherein said method comprises administering said compound to the subject as an intravenous infusion at a dose rate of between about 200 pg / h and about 2.5 mg / h over a period of at least 12 hours.

[0018] The invention also provides a method of treating or preventing a KMO mediated disorder in a human subject; the method comprising administering a compound which is a benzisoxazole of formula (I) or a pharmaceutically acceptable salt thereof: to the subject as an intravenous infusion at a dose rate of between about 200 pg / h and about

[0019] 2.5 mg / h over a period of at least 12 hours.

[0020] The invention additionally provides the use of a compound for the manufacture of a medicament for use in a method of treating a KMO mediated disorder in a human subject; wherein said compound is a benzisoxazole of formula (I) or a pharmaceutically acceptable salt thereof: and wherein said method comprises administering said medicament to the subject as an intravenous infusion at a dose rate of between about 200 pg / h and about 2.5 mg / h over a period of at least 12 hours.

[0021] The invention additionally provides a method in which a benzisoxazole of formula (I) or a pharmaceutically acceptable salt thereof: is delivered to a human subject as an intravenous infusion in an amount suitable to achieve a reduction of plasma 3HK levels in the subject of at least 50% compared to baseline.

[0022] BRIEF DESCRIPTION OF THE FIGURES

[0023] Figure 1 shows concentration vs time profiles in Part A (Single dose administration). Figure 2 shows concentration vs time profiles in Part B (Intravenous infusion). In Part B, Treatment 60 pg Compound 1 : 60 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 40 pg / h Compound 1 continuous IV infusion over 7 days;

[0024] Treatment 120 pg: 120 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 80 pg / h Compound 1 continuous IV infusion over 7 days, Treatment 360 pg Compound 1 : 360 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 240 pg / h Compound 1 continuous IV infusion over 7 days.

[0025] Figure 3 shows changes in plasma KYN, KYNA (kynurenic acid) and 3HK at 200, 600 and 1000pg / 0.5h.

[0026] Figure 4 shows changes in plasma 3HK in Part B (Intravenous infusion). In Part B, Treatment 60 pg Compound 1 : 60 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 40 pg / h Compound 1 continuous IV infusion over 7 days; Treatment 120 pg: 120 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 80 pg / h Compound 1 continuous IV infusion over 7 days, Treatment 360 pg Compound 1 : 360 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 240 pg / h Compound 1 continuous IV infusion over 7 days.

[0027] Figure 5 shows changes in plasma KYN and KYNA in Part B (Intravenous infusion). In Part B, Treatment 60 pg Compound 1 : 60 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 40 pg / h Compound 1 continuous IV infusion over 7 days;

[0028] Treatment 120 pg: 120 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 80 pg / h Compound 1 continuous IV infusion over 7 days, Treatment 360 pg Compound 1 : 360 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 240 pg / h Compound 1 continuous IV infusion over 7 days.

[0029] DETAILED DESCRIPTION

[0030] The benzisoxazole of formula (I) and pharmaceutically acceptable salts thereof are referred to hereinafter as “compounds of the invention”. Included within the scope of the compounds of the invention are all solvates (including hydrates), complexes, polymorphs, prodrugs, radiolabelled derivatives, and stereoisomers of a benzisoxazole of formula (I) and pharmaceutically acceptable salts thereof.

[0031] Pharmaceutically acceptable salts

[0032] The present invention relates to a benzisoxazole of formula (I) and pharmaceutically acceptable salts thereof. Other salts may, however, be useful in the preparation of a benzisoxazole of formula (I) or of its pharmaceutically acceptable salts. The compound may be in its free base form. The term “free base form” refers to the uncharged molecule i.e. the molecule without any negative or positive charges (for instance protons co-ordinated to nitrogen).

[0033] The benzisoxazole of formula (I) is capable of forming base addition salts. Such salts can be formed by reaction with the appropriate base, optionally in a suitable solvent such as an organic solvent, to give the salt which can be isolated by crystallisation and filtration.

[0034] The benzisoxazole of formula (I) is also capable of forming acid addition salts. Such salts can be formed by reaction with the appropriate acid, optionally in a suitable solvent such as an organic solvent, to give the salt which can be isolated by crystallisation and filtration.

[0035] As used herein the term ‘pharmaceutically acceptable salts’ refers to salts that retain the desired biological activity of the subject compound and exhibit minimal undesired toxicological effect. Pharmaceutically acceptable salts will be apparent to those skilled in the art and include those described in Berge, J. Pharm. Sci., 1977, 66, 1-19.

[0036] Pharmaceutically acceptable base salts include, but are not limited to, ammonium salts, alkali metal salts such as those of sodium and potassium, alkaline earth metal salts such as those of calcium and magnesium and salts with organic bases, including salts of primary, secondary and tertiary amines, such as t-butylamine, cyclohexylamine, dimethylamine, trimethylamine, diethyltriamine, 2-amino-2-(hydroxymethyl)-l,3-propanediol (TRIS), ethanolamine and N- methyl-D-glucamine. Pharmaceutically acceptable base addition salts include, but are not limited to, ammonium salts, alkali metal salts such as those of sodium and potassium, alkaline earth metal salts such as those of calcium and magnesium and salts with organic bases, including salts of primary, secondary and tertiary amines, such as t-butylamine, cyclohexyl amine, dimethylamine, trimethylamine, di ethyltriamine, 2-amino-2-(hydroxymethyl)- 1,3 -propanediol (TRIS), ethanolamine, choline and N-methyl-D-glucamine.

[0037] Pharmaceutically acceptable acid salts include, but are not limited to, hydrochloride, hydrobromide, nitrate, methylnitrate, sulfate, bi sulfate, sulfamate, phosphate, acetate, hydroxyacetate, phenyl acetate, propionate, butyrate, isobutyrate, valerate, maleate, hydroxymaleate, acrylate, fumarate, malate, tartrate, citrate, salicylate, p-aminosalicyclate, glycollate, lactate, heptanoate, phthalate, oxalate, succinate, benzoate, o-acetoxybenzoate, chlorobenzoate, methylbenzoate, dinitrobenzoate, hydroxybenzoate, methoxybenzoate, mandelate, tannate, formate, stearate, ascorbate, palmitate, oleate, pyruvate, pamoate, malonate, laurate, glutarate, glutamate, estolate, methanesulfonate (mesylate), ethanesulfonate (esylate), 2-hydroxyethanesulfonate, benzenesulfonate (besylate), p-aminobenzenesulfonate, p-toluenesulfonate (tosylate), napthalene-2-sulfonate, ethanedisulfonate, and 2,5- dihy droxyb enzoate .

[0038] Pharmaceutically acceptable acid addition salts include, but are not limited to, hydrochloride, hydrobromide, nitrate, methylnitrate, sulfate, bi sulfate, sulfamate, phosphate, acetate, hydroxyacetate, phenyl acetate, propionate, butyrate, isobutyrate, valerate, maleate, hydroxymaleate, acrylate, fumarate, malate, tartrate, citrate, salicylate, p-aminosalicyclate, glycollate, lactate, heptanoate, phthalate, oxalate, succinate, benzoate, o-acetoxybenzoate, chlorobenzoate, methylbenzoate, dinitrobenzoate, hydroxybenzoate, methoxybenzoate, mandelate, tannate, formate, stearate, ascorbate, palmitate, oleate, pyruvate, pamoate, malonate, laurate, glutarate, glutamate, estolate, methanesulfonate (mesylate), ethanesulfonate (esylate), 2-hydroxyethanesulfonate, benzenesulfonate (besylate), p-aminobenzenesulfonate, p-toluenesulfonate (tosylate), napthalene-2-sulfonate, ethanedisulfonate, and 2,5- dihy droxyb enzoate . It is to be understood that the references herein to a benzisoxazole of formula (I) and pharmaceutically acceptable salts thereof covers a benzisoxazole of formula (I) as a free base, free acid or as pharmaceutically acceptable salts thereof. The compound of the invention may be a benzisoxazole of formula (I) as the free base. The compound of the invention may be a benzisoxazole of formula (I) as the free acid. The compound of the invention may be a pharmaceutically acceptable salt of the benzisoxazole of formula (I).

[0039] Solvates

[0040] Certain compounds of the invention may exist in the form of solvates. As used herein, the term “solvate” refers to a complex of variable stoichiometry formed by a solute (in this invention, a benzisoxazole of formula (I) and pharmaceutically acceptable salts thereof) and a solvent. Such solvents for the purpose of the invention may not interfere with the biological activity of the solute. Examples of suitable solvents include water, methanol, ethanol and acetic acid. If the solvent used is water, the solvate may be referred to as a hydrate.

[0041] Isomers

[0042] Compounds of the invention have an asymmetric centre (also referred to as a chiral centre). Where the stereochemistry of a chiral centre in any chemical structure illustrated herein is not specified, the structure is intended to encompass any stereoisomer and all mixtures thereof.

[0043] In addition, compounds of formula (I) may exist as tautomers, for example keto (CH2C=O)^enol (CH=CHOH) tautomers. Formula (I) is intended to represent all individual tautomers and all possible mixtures thereof, unless stated or shown otherwise.

[0044] ‘Enantiomeric excess’ (ee) is the excess of one enantiomer over the other expressed as a percentage. In a racemic modification, since both enantiomers are present in equal amounts, the enantiomeric excess is zero (0% ee). However, if one enantiomer were enriched such that it constitutes 95% of the product, then the enantiomeric excess would be 90% ee (the amount of the enriched enantiomer, 95%, minus the amount of the other enantiomer, 5%).

[0045] ‘Enantiomerically enriched’ refers to products whose enantiomeric excess (ee) is greater than zero. For example, ‘enantiomerically enriched’ refers to products whose enantiomeric excess is greater than 50% ee, greater than 75% ee, or greater than 90% ee. For example, a benzisoxazole of formula (I), or a pharmaceutically acceptable salt thereof, as described herein is enantiomerically enriched in the (R) isomer.

[0046] ‘Enantiomerically pure’ refers to products whose enantiomeric excess is 99% or greater.

[0047] The (R) enantiomer of a benzisoxazole of formula (I), or a pharmaceutically acceptable salts thereof, may be present in greater than 95% ee.

[0048] The (R) enantiomer of a benzisoxazole of formula (I), or a pharmaceutically acceptable salts thereof, may be present in greater than 99% ee.

[0049] Crystalline forms

[0050] It will be further appreciated that certain compounds of the invention that exist in crystalline form, including the various solvates thereof, may exhibit polymorphism (i.e. the capacity to occur in different crystalline structures). These different crystalline forms are typically known as ‘polymorphs’. The invention includes such polymorphs. Polymorphs have the same chemical composition but differ in packing, geometrical arrangement, and other descriptive properties of the crystalline solid state. Polymorphs, therefore, may have different physical properties such as shape, density, hardness, deformability, stability, and dissolution properties. Polymorphs typically exhibit different melting points, IR spectra, and X-ray powder diffraction patterns, which may be used for identification. It will be appreciated that different polymorphs may be produced, for example, by changing or adjusting the reaction conditions or reagents, used in making the compound. For example, changes in temperature, pressure, or solvent may result in polymorphs. In addition, one polymorph may spontaneously convert to another polymorph under certain conditions.

[0051] Isotopic labelling

[0052] The benzisoxazole of formula (I) and pharmaceutically acceptable salts thereof may be isotopically-labelled and as such are identical to compounds of the invention, but for one or more atoms having been replaced by an atom having an atomic mass or mass number different from the atomic mass or mass number most commonly found in nature. Examples of isotopes that can be incorporated into compounds of the invention are isotopes of hydrogen, carbon, nitrogen, fluorine, such as3H,nC,14C and18F. Isotopically labelled compounds of the invention can generally be prepared by carrying out the procedures disclosed below, by substituting a readily available isotopically labelled reagent for a non-isotopically labelled reagent.

[0053] Prodrugs

[0054] Prodrugs of the compounds of the invention are included within the scope of the present invention.

[0055] As used herein, the term “prodrug” means a compound which is converted within the body, e.g. by hydrolysis in the blood, into its active form that has medical effects. Pharmaceutically acceptable prodrugs are described in T. Higuchi and V. Stella, Prodrugs as Novel Delivery Systems, Vol. 14 of the A.C.S. Symposium Series, and in Edward B. Roche, ed., Bioreversible Carriers in Drug Design, American Pharmaceutical Association and Pergamon Press, 1987 and in D. Fleishner, S. Ramon and H. Barba “Improved oral drug delivery: solubility limitations overcome by the use of prodrugs”, Advanced Drug Delivery Reviews (1996) 19(2) 115-130. Prodrugs are any covalently bonded carriers that release a compound of formula (I) in vivo when such prodrug is administered to a patient. Prodrugs are generally prepared by modifying functional groups in a way such that the modification is cleaved in vivo yielding the parent compound. Prodrugs may include, for example, compounds of the invention wherein the carboxylic acid group is bonded to any group that, when administered to a patient, cleaves to form the carboxylic acid group. Thus, representative examples of prodrugs include (but are not limited to) phosphonate, carbamate, acetate, formate and benzoate derivatives of the carboxylic acid functional group of the compounds of the invention.

[0056] Administration of compounds of the invention

[0057] The present invention provides compounds of the invention for use in a method of treating or preventing a KMO mediated disorder in a subject in need thereof, wherein the subject is a human subject. Said method comprises administering compounds of the invention to the subject as an intravenous infusion at a dose rate of between about 200 pg / h and about 2.5 mg / h over a period of at least 12 hours. Typically, said intravenous infusion has a dose rate of between about 240 pg / h and about 2.5 mg / h; preferably said intravenous infusion has a dose rate of between about 240 pg / h and about 2.25 mg / h.

[0058] Sometimes, said intravenous infusion has a dose rate of between about 240 pg / h and about 2.0 mg / h; between about 240 pg / h and about 1.75 mg / h; or between about 240 pg / h and about 1.5 mg / h.

[0059] The compounds of the invention may, for example, be administered to the subject as an intravenous infusion at a dose rate of about 200 pg / h, 220 pg / h, 240 pg / h, 260 pg / h, 280 pg / h, 300 pg / h, 320 pg / h, 340 pg / h, 360 pg / h, 380 pg / h, 400 pg / h, 420 pg / h, 440 pg / h, 460 pg / h,

[0060] 480 pg / h, 500 pg / h, 520 pg / h, 540 pg / h, 560 pg / h, 580 pg / h, 600 pg / h, 620 pg / h, 640 pg / h,

[0061] 660 pg / h, 680 pg / h, 700 pg / h, 720 pg / h, 740 pg / h, 760 pg / h, 780 pg / h, 800 pg / h, 820 pg / h,

[0062] 840 pg / h, 860 pg / h, 880 pg / h, 900 pg / h, 920 pg / h, 940 pg / h, 960 pg / h, 980 pg / h, 1 mg / h,

[0063] 1.25 mg / h, 1.5 mg / h, 1.75 mg / h, 2 mg / h, 2.1 mg / h, 2.25 mg / h or 2.5 mg / h.

[0064] The compounds of the invention are administered to the subject as an intravenous infusion over a period of at least 12 hours.

[0065] The compounds of the invention may be administered to the subject as an intravenous infusion for a period of at least 12 hours, at least 1 day, at least 2 days, at least 3 days, at least 4 days, at least 5 days, at least 6 days, at least 7 days, at least 8 days, at least 9 days, at least 10 days, at least 11 days, at least 12 days, at least 13 days, or at least 14 days.

[0066] The compounds of the invention may be administered to the subject as an intravenous infusion for a period of up to 1 day, up to 2 days, up to 3 days, up to 4 days, up to 5 days, up to 6 days, up to 7 days, up to 8 days, up to 9 days, up to 10 days, up to 11 days, up to 12 days, up to 13 days, up to 14 days, up to 15 days, up to 16 days, up to 17 days, up to 18 days, up to 19 days, up to 20 days, up to 21 days, up to 22 days, up to 23 days, up to 24 days, up to 25 days, up to 26 days, up to 27 days, up to 28 days, up to 29 days, up to 30 days, up to 31 days, up to 1 month, or longer.

[0067] Typically, the compounds of the invention are administered to the subject as an intravenous infusion for a period of between 1 day and one month, for example between 1 day and 28 days. In typical embodiments, the compounds of the invention are administered to the subject as an intravenous infusion for a period of between 1 and 14 days, for example between 1 and 7 days, or between 1 and 5 days. In alternative embodiments, the compounds of the invention are administered to the subject as an intravenous infusion for a period of between 2 and 14 days, for example between 3 and 10 days, or between 4 and 7 days.

[0068] The compounds of the invention may, for example, be administered to the subject as an intravenous infusion for a period of about 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 11 days, 12 days, 13 days, 14 days, 15 days, 16 days, 17 days, 18 days, 19 days, 20 days, 21 days, 22 days, 23 days, 24 days, 25 days, 26 days, 27 days, 28 days, 29 days, 30 days, 31 days, or 1 month.

[0069] It will be understood by those skilled in the art that the time period of the intravenous infusion may include certain time periods during which the compound is not being administered, for example where a break in the administration is deemed necessary for reasons such as patient comfort or logistical necessity. Other than such possible breaks in the infusion, typically the intravenous infusion is continuous. Such continuous infusion typically involves administering the compound of the invention to the subject throughout the period of administration, with breaks in the infusion of no more than one hour, preferably no more than 30 minutes, preferably no more than 15 minutes. For example, such continuous infusion may comprise one or more breaks in the infusion of from 0 to 15 minutes, from 0 to 30 minutes, or from 0 to 1 hour.

[0070] It will be understood by those skilled in the art that the dose rate of the intravenous infusion is typically constant or substantially constant over the time period of the intravenous infusion. However, in certain situations, the dose rate may vary. For example, where deemed necessary for reasons such as logistical necessity such as the change of an IV bag or to account for a necessary break in the infusion as described above. The dose rate may also vary for reasons related to the dosing equipment. The dose rate may also vary where deemed appropriate by the treating clinician to vary the dose, for example, due to reasons of change in severity of the patient’s condition.

[0071] In some embodiments, said method of treating or preventing a KMO mediated disorder in a subject in need thereof includes administering a bolus dose of the compound of the invention to the subject.

[0072] In some instances, said method of treating or preventing a KMO mediated disorder in a subject in need thereof may additionally comprise administering a bolus dose of the compound of the invention to the subject at a dosage of between about 350 pg and about 20 mg.

[0073] It will be understood by a person skilled in the art that a bolus dose is typically regarded to be a rapid high-dose administration of a compound of the invention. For example, in the context of the present application, a bolus may be a higher dose of a compound of the invention and / or the bolus dose may be more rapidly administered than the intravenous infusion described above (also referred to herein as a maintenance infusion). In particular, the administration of such a bolus dose can be advantageous in rapidly achieving a target plasma concentration of the compound of the invention which can allow more rapid KMO inhibition and improved clinical outcomes.

[0074] Typically, said bolus is administered at a dosage of between about 350 pg and about 18 mg; preferably between about 350 pg and about 10 mg; more preferably between about 350 pg and about 6 mg of said compound; further preferably between about 500 pg and about 6 mg of said compound, or between about 1 mg and 6 mg of said compound. For example, the bolus may be administered at a dosage of between about 350 pg and about 18 mg; between about 400 pg and about 10 mg; between about 450 pg and about 6 mg of said compound; between about 500 pg and about 6 mg; between about 600 pg and about 6 mg; or between about 800 pg and about 6 mg of said compound. Said bolus may, for example, be administered at a dosage of about 350 pg, 360 pg, 370 pg, 380 pg, 390 pg, 400 pg, 450 pg, 500 pg, 550 pg, 600 pg, 650 pg, 700 pg, 750 pg, 800 pg, 850 pg, 900 pg, 950 pg, 1 mg, 2 mg, 3 mg, 4 mg, 5 mg, 6 mg, 7 mg, 8 mg, 9 mg, 10 mg, 11 mg, 12 mg, 13 mg, 14 mg, 15 mg, 16 mg, 17 mg, 18 mg, 19 mg, or 20 mg.

[0075] Preferably, said bolus is administered before the intravenous infusion.

[0076] Said bolus may be administered as an intravenous injection. Alternatively, said bolus may be administered as an intravenous infusion.

[0077] Said method may therefore comprise administering a compound of the invention as (i) a bolus of between about 350 pg and about 20 mg; and subsequently (ii) an intravenous infusion at a dose rate of about 200 pg / h and about 2.5 mg / h.

[0078] When the bolus is administered as an intravenous infusion, said bolus infusion may be administered for a period of up to 1 hour, up to 45 minutes, up to 30 minutes, or up to 15 minutes. Said bolus infusion may be administered at a dose rate of between about 350 pg / h and about 80 mg / h, preferably between about 700 pg / h and about 36 mg / h, more preferably between about 1 mg / h and about 20 mg / h, for example between about 2 mg / h and about 10 mg / h.

[0079] Said method may therefore comprise administering a bolus infusion at a dose rate of between about 350 pg / h and about 80 mg / h, preferably between about 700 pg / h and about 36 mg / h, more preferably between about 1 mg / h and about 20 mg / h, for example between about 2 mg / h and about 10 mg / h; followed by a maintenance infusion at a dose rate of between about 200 pg / h and about 2.5 mg / h for at least 12 hours. Said maintenance infusion may be at a dose rate of between about 240 pg / h and about 2.5 mg / h; preferably between about 240 pg / h and about 2.25 mg / h. Said bolus infusion may be administered for a period of up to 1 hour, for example up to 45 minutes, preferably up to 30 minutes, for example up to 15 minutes, and the maintenance infusion may be administered for a period of between 1 and 28 days, for example between 1 and 14 days, between 1 and 7 days, or between 1 and 5 days. In alternative embodiments, said method of treating or preventing a KMO mediated disorder in a subject in need thereof does not include administering a bolus dose of the compound of the invention to the subject. The present inventors have found that the plasma concentration of the administered drug increases rapidly following administration, removing the necessity to administer a higher dose at the start of administration. In these embodiments, the administration regime typically comprises administering the drug to the subject at a single dosage substantially throughout the period of administration. Typically, the single dosage is administered as a continuous intravenous infusion, for the time periods set out herein.

[0080] The benzisoxazole of formula (I) or pharmaceutically acceptable salt thereof may be administered to the subject in the form of a pharmaceutical composition which is suitable for intravenous administration, e.g. by injection or infusion.

[0081] The compositions for intravenous administration may take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilising, preserving and / or dispersing agents. Alternatively, the active ingredients may be in powder form for constitution with a suitable vehicle, e.g. sterile pyrogen-free water, before use.

[0082] Such pharmaceutical compositions may also comprise one or more pharmaceutically acceptable excipients, as described herein. Such pharmaceutical compositions may therefore comprise a benzisoxazole of formula (I) or a pharmaceutically acceptable salts thereof and one or more pharmaceutically acceptable excipients, as described herein.

[0083] Suitable pharmaceutically acceptable excipients are well known to those skilled in the art and include pharmaceutically acceptable carriers (e.g. a saline solution, an isotonic solution), diluents, = buffers, buffering agents, preservatives, anti-oxidants, , solvents, co-solvents, , chelating agents, plasticisers, viscosity increasing agents, stabilisers, solubilisers, surfactants (e.g. wetting agents), masking agents, colouring agents, . Suitable carriers, diluents, excipients, etc. can be found in standard pharmaceutical texts. See, for example, Handbook for Pharmaceutical Additives, 2nd Edition (eds. M. Ash and I. Ash), 2001 (Synapse Information Resources, Inc., Endicott, New York, USA), Remington's Pharmaceutical Sciences, 20th edition, pub. Lippincott, Williams & Wilkins, 2000; and Handbook of Pharmaceutical Excipients, 2nd edition, 1994.

[0084] The skilled artisan will appreciate that certain pharmaceutically acceptable excipients may serve more than one function and may serve alternative functions depending on how much of the excipient is present in the formulation and what other excipients are present in the formulation.

[0085] Skilled artisans possess the knowledge and skill in the art to enable them to select suitable pharmaceutically acceptable excipients in appropriate amounts for use in the invention. In addition, there are a number of resources that are available to the skilled artisan which describe pharmaceutically acceptable excipients and may be useful in selecting suitable pharmaceutically acceptable excipients. Examples include Remington's Pharmaceutical Sciences (Mack Publishing Company), The Handbook of Pharmaceutical Additives (Gower Publishing Limited), and The Handbook of Pharmaceutical Excipients (the American Pharmaceutical Association and the Pharmaceutical Press).

[0086] Reduction of 3HK levels

[0087] Administration of compounds of the invention will result in inhibition of KMO and will reduce production of 3HK in a subject.

[0088] Plasma 3-HK levels can be determined according to methods known in the art, e.g. by LC- MS-MS [Fernando et al. Br. J. Clin. Pharmacol. 2022: 88: 865-870], Briefly such methods involve, for example, solvent extraction of 3-HK from plasma before quantification against an internal standard using LC-MS-MS methods.

[0089] Administration of compounds of the invention as described above may accordingly reduce plasma 3HK levels in a subject compared to baseline. Preferably, administration of compounds of the invention may provide a reduction of plasma 3HK levels in the subject of at least 50% compared to baseline. Administration of compounds of the invention as described above may also provide a reduction of plasma 3HK levels in the subject of at least 75% compared to baseline; of at least 80% compared to baseline; preferably of at least 85% compared to baseline; more preferably of at least 90% compared to baseline; and most preferably of at least 95% compared to baseline.

[0090] As used herein, baseline is defined as being the level of 3HK present in a subject prior to administration of a compound of the invention. Baseline may be assessed at any suitable time prior to administration of a compound of the invention. As used herein a baseline measurement is a measurement taken at the start of treatment, such as immediately before (e.g. up to 1 hour before) the first administration of a compound as described herein.

[0091] Also described herein are methods in which compounds of the invention are delivered in an amount effective to achieve a reduction of plasma 3HK levels in the subject of at least 50% compared to baseline. Typically, the amount of the compound of the invention delivered is effective to achieve a reduction of plasma 3HK levels in the subject of at least 75% compared to baseline. The amount of the compound of the invention delivered may be effective to achieve a reduction of plasma 3HK levels in the subject of at least 80% compared to baseline; preferably of at least 85% compared to baseline; more preferably of at least 90% compared to baseline; and most preferably of at least 95% compared to baseline.

[0092] Typically, the compounds as described above may be administered to a subject with elevated 3HK levels and administration of the compound will reduce the subject’s 3HK levels.

[0093] Administration of the compound may therefore restore 3HK homeostasis, or may reduce 3HK levels to or towards homeostatic levels. Therefore, also described herein are methods in which compounds of the invention are delivered in an amount effective to reduce 3HK levels, for example to return an elevated level of plasma 3HK to homeostasis.

[0094] It must also be understood that 3HK levels in a subject suffering from a KMO mediated disorder may increase in absolute terms, although administration of the compound will reduce the production of 3HK and thereby may reduce the rate and / or amount of increase of 3HK levels. Therefore, also described herein are methods in which compounds of the invention are delivered in an amount effective to reduce the rate of increase of 3HK levels. As used herein, homeostasis is defined as being the level of 3HK present in an average, otherwise healthy subject. Typically, a healthy subject would have a plasma 3HK concentration of around 2 ng / mL to 20 ng / mL.

[0095] When determining the effective amount suitable to achieve a reduction of plasma 3HK levels in the subject, an ‘effective amount’ in reference to a compound of the invention means an amount of the active compound sufficient to treat the patient's condition within the scope of sound medical judgment. An effective amount of a compound of the invention will vary with the particular compound chosen (for example, the potency, efficacy, and half-life of the compound will be considered); the disorder being treated; the severity of the disorder being treated; the age, size, weight, and physical condition of the patient being treated; the medical history of the patient to be treated; the duration of the treatment; the nature of concurrent therapy; the desired therapeutic effect; and like factors, but can nevertheless be routinely determined by the skilled artisan.

[0096] Treatment or prevention ofKMO mediated disorders

[0097] Certain compounds of the invention are inhibitors ofKMO. Compounds which inhibit KMO may be useful in the treatment or prevention of various conditions or disorders mediated by KMO, for example acute pancreatitis, chronic kidney disease, acute kidney disease, acute kidney injury, other conditions associated with systemic inflammatory response syndrome (SIRS), Huntington's disease, Alzheimer's disease, spinocerebellar ataxias, Parkinson's disease, AIDS-dementia complex, HIV infection, amyotrophic lateral sclerosis (ALS), depression, schizophrenia, sepsis, cardiovascular shock, severe trauma, acute lung injury, acute respiratory distress syndrome, acute cholecystitis, severe bums, pneumonia, extensive surgical procedures, ischemic bowel, severe acute hepatic disease, severe acute hepatic encephalopathy or acute renal failure.

[0098] Additional conditions or disorders include hyperproliferative diseases of benign or malignant behaviour, in which cells of various tissues and organs exhibit aberrant patterns of growth, proliferation, migration, signalling, senescence, and death. Generally, hyperproliferative disease refers to diseases and disorders associated with the uncontrolled proliferation of cells, including but not limited to uncontrolled growth of organ and tissue cells resulting in cancers and benign tumours. Hyperproliferative disorders associated with endothelial cells can result in diseases of angiogenesis such as angiomas, endometriosis, obesity, age-related macular degeneration and various retinopathies, as well as the proliferation of ECs and smooth muscle cells that cause restenosis as a consequence of stenting in the treatment of atherosclerosis.

[0099] Hyperproliferative disorders involving fibroblasts (i.e. fibrogenesis) include but are not limited to disorders of excessive scaring (i.e. fibrosis) such as age-related macular degeneration, cardiac remodelling and failure associated with myocardial infarction, excessive wound healing such as commonly occurs as a consequence of surgery or injury, keloids, and fibroid tumours and stenting.

[0100] Further such conditions or disorders include transplant rejection (suppression of T-cells) and graft vs host disease, systemic inflammatory disorders, brain inflammatory disorders including malaria and African trypanosomiasis, and pneumococcal meningitis.

[0101] Further such conditions or disorders include cirrhosis, chronic pancreatitis, liver fibrosis, lung fibrosis and ischemia-reperfusion injury.

[0102] Further such conditions or disorders include, for example, neurodegenerative diseases, psychiatric or neurological diseases or disorders, Creutzf eld- Jacob disease, trauma-induced neurodegeneration, high-pressure neurological syndrome, dystonia, olivopontocerebellar atrophy, multiple sclerosis, epilepsy, consequences of stroke, cerebral ischemia, ischemic disorders including stroke (focal ischemia), hypoxia, multi-infarct dementia, consequences of cerebral trauma or damage, damage to the spinal cord, dementia such as senile dementia, AIDS-induced encephalopathy, other infection related encephalopathy, viral or bacterial meningitis, infectious diseases caused by viral, bacterial and other parasites, (for example, general central nervous system (CNS) infections such as viral, bacterial or parasitic infection, for example, poliomyelitis, Lyme disease (Borrelia burgdorferi infection)) septic shock, and cancers, cancers with cerebral localization, hepatic encephalopathy, systemic lupus, analgesia and opiate withdrawal symptoms, feeding behaviour, psychiatric disorders, such as insomnia, severe deficit in working memory, severe deficit in long term memory storage, decrease in cognition, severe deficit in attention, severe deficit in executive functioning, slowness in information processing, slowness in neural activity, anxiety, generalized anxiety disorders, panic anxiety, obsessive compulsive disorders, social phobia, performance anxiety, post- traumatic stress disorder, acute stress reaction, adjustment reaction, separation anxiety disorder, alcohol withdrawal anxiety, depressive disorders, disorders of the developing or aged brain, diabetes, and complications thereof, Tourette's syndrome, Fragile X syndrome, autism spectrum disorders, disorders that cause severe and pervasive impairment in thinking feeling, language and the ability to relate to others, mood disorders, psychological disorders characterized by abnormalities of emotional state, such as without limitation, bipolar disorder, unipolar depression, major depression, endogenous depression, involutional depression, reactive depression, psychotic depression, depression caused by underlying medical conditions, cyclothymic disorders, dysthymic disorders, mood disorders due to general medical condition, mood disorders not otherwise specified and substance-induced mood disorders.

[0103] Further such conditions or disorders also include, for example, acute necrotizing pancreatitis, AIDS (disease), aseptic meningitis, brain disease, for example, Gilles de la Tourette syndrome, Asperger syndrome, Rett syndrome, pervasive developmental disorders, aging- related brain disease, and developmental brain disease, burnout syndrome, carbon monoxide poisoning, cardiac arrest or insufficiency and hemorrhagic shock (global brain ischemia), cataract formation and aging of the eye, central nervous system disease, cerebrovascular disease, chronic fatigue syndrome, chronic stress, cognitive disorders, convulsive disorders, such as variants of grand mal and petit mal epilepsy and Partial Complex Epilepsy, diabetes mellitus, disease of the nervous system (e.g., dyskinesia, L-DOPA induced movement disorders, drug addiction, pain and cataract), drug dependence, drug withdrawal, feeding disorders, Guillain Barr Syndrome and other neuropathies, immune disease, immunitary disorders and therapeutic treatment aimed at modifying biological responses (for instance administrations of interferons or interleukins), inflammatory disorders of the central and / or peripheral nervous system, Injury (trauma, polytrauma), Mental and behavioural disorders, metabolic disease, pain disease, or disorder selected from a group of inflammatory pain, neurophathic pain or migraine, allodynia, hyperalgesia pain, phantom pain, neuropathic pain related to diabetic neuropathy, multiple organ failure, near drowning, necrosis, neoplasms of the brain, neoplastic disorders including lymphomas and other malignant blood disorders, nervous system disease (high-pressure neurological Syndrome, infection), nicotine addiction and other addictive disorders including alcoholism, cannabis, benzodiazepine, barbiturate, morphine and cocaine dependence, change in appetite, sleep disorders, changes in sleep pattern, lack of energy, fatigue, low self-esteem, self-reproach inappropriate guilt, frequent thoughts of death or suicide, plans or attempts to commit suicide, feelings of hopelessness and worthlessness, psychomotor agitation or retardation, diminished capacity for thinking, concentration, or decisiveness, as a neuroprotective agent, spinal cord disease, systemic lupus erythematosis, traumatic damage to the brain and spinal cord, and tremor syndromes and poor balance, brakykinesia, rigidity, tremor, change in speech, loss of facial expression, micrographia, difficulty swallowing, drooling, confusion, fear, sexual dysfunction, language impairment, impairment in decision making, violent outbursts, aggression, hallucination, apathy, impairment in abstract thinking.

[0104] Further such conditions or disorders also include, for example, cardiovascular diseases, which refer to diseases and disorders of the heart and circulatory system. These diseases are often associated with dyslipoproteinemias and / or dyslipidemias. Cardiovascular diseases include, but are not limited to, cardiomegaly, atherosclerosis, myocardial infarction, and congestive heart failure, coronary heart disease, hypertension and hypotension.

[0105] Compounds which inhibit KMO may particularly be useful in treating or preventing a KMO mediated disorder selected from the group consisting of: acute pancreatitis, chronic kidney disease, acute kidney disease, acute kidney injury, systemic inflammatory response syndrome (SIRS), sepsis, cardiovascular shock, severe trauma, acute lung injury, acute respiratory distress syndrome, acute cholecystitis, pneumonia, ischemic bowel, severe acute hepatic disease, severe acute hepatic encephalopathy or acute renal failure.

[0106] Preferably said KMO mediated disorder is acute pancreatitis. Equally preferably said KMO mediated disorder is acute kidney injury. Equally preferably said KMO mediated disorder is SIRS. Equally preferably said KMO mediated disorder is sepsis.

[0107] As used herein, ‘treat’ or ‘treatment’ in reference to a disorder means: (1) to ameliorate or prevent the disorder or one or more of the biological manifestations of the disorder, (2) to interfere with (a): one or more points in the biological cascade that leads to or is responsible for the disorder, or (b): one or more of the biological manifestations of the disorder, (3) to alleviate one or more of the symptoms or effects associated with the disorder, or (4) to slow the progression of the disorder or one or more of the biological manifestations of the disorder.

[0108] It will be appreciated that ‘prevention’ is not an absolute term. In medicine, ‘prevention’ is understood to refer to the prophylactic administration of a drug to substantially diminish the likelihood or severity of a disorder or biological manifestation thereof, or to delay the onset of such disorder or biological manifestation thereof. ‘Prevention’ also includes prophylaxis.

[0109] As used herein, a subject in need thereof is any subject in which treatment with a compound of the invention would treat or prevent a KMO-mediated disorder. The subject is a human.

[0110] For example, the subject may have acute pancreatitis. A subject may have severe acute pancreatitis, in other words, the KMO mediated disorder is severe acute pancreatitis. Severe acute pancreatitis in a subject may be defined as said subject having persistent organ failure. Severe acute pancreatitis in a subject may be defined as said subject having organ failure persisting for 48 hours or more. A subject may have critical acute pancreatitis, in other words, the KMO mediated disorder is critical acute pancreatitis. Critical acute pancreatitis in a subject may be defined as said subject having persistent organ failure and having infected (peri-)pancreatic necrosis. Accordingly, the subject to be treated may have severe or critical acute pancreatitis. Accordingly, the KMO mediated disorder may be severe or critical acute pancreatitis. The subject having acute pancreatitis, in particular severe acute pancreatitis or critical acute pancreatitis, may be being treated in an intensive care unit (ICU).

[0111] The subject may have suffered trauma, in particular severe trauma. The subject may have suffered a burn or bums, in particular a severe burn or burns. The subject may have had surgery, in particular cardiac surgery.

[0112] As such, said method may be a method of treating or preventing a KMO mediated disorder in a subject suffering from acute pancreatitis. For example, said method may be a method of treating or preventing systemic inflammatory response syndrome in a subject suffering from acute pancreatitis. Said method may be a method of treating or preventing multiple organ dysfunction syndrome (MODS) in a subject suffering from acute pancreatitis. Particularly, said method may be a method of treating or preventing acute kidney injury in a subject suffering from acute pancreatitis.

[0113] Said method may be a method of treating or preventing a KMO mediated disorder in a subject suffering from trauma, in particular severe trauma. For example, said method may be a method of treating or preventing systemic inflammatory response syndrome in a subject suffering from trauma, in particular severe trauma. Said method may be a method of treating or preventing multiple organ dysfunction syndrome (MODS) in a subject trauma, in particular severe trauma. Particularly, said method may be a method of treating or preventing acute kidney injury in a subject suffering from trauma, in particular severe trauma.

[0114] Said method may be a method of treating or preventing a KMO mediated disorder in a subject that suffering from a burn or bums, in particular a severe burn or burns. For example, said method may be a method of treating or preventing systemic inflammatory response syndrome in a subject suffering from a bum or burns, in particular a severe burn or bums. Said method may be a method of treating or preventing multiple organ dysfunction syndrome (MODS) in a subject suffering from a burn or burns, in particular a severe burn or burns. Particularly, said method may be a method of treating or preventing acute kidney injury in a subject suffering from a bum or burns, in particular a severe burn or bums.

[0115] Said method may be a method of treating or preventing a KMO mediated disorder in a subject that has had surgery, for example cardiac surgery. For example, said method may be a method of treating or preventing systemic inflammatory response syndrome in a subject that has had surgery, for example cardiac surgery. Said method may be a method of treating or preventing multiple organ dysfunction syndrome (MODS) in a subject that has had surgery, for example cardiac surgery. Particularly, said method may be a method of treating or preventing acute kidney injury in a subject that has had surgery, in particular cardiac surgery.

[0116] The following examples serve to illustrate the invention but are not limiting on the scope of the invention. EXAMPLES

[0117] As used in the following examples, plasma 3-HK levels can be determined according to LC- MS-MS methods known in the art, such as those in Fernando et al. [Fernando et al. Br. J. Clin. Pharmacol. 2022: 88: 865-870],

[0118] Example 1 - Preparation of compounds of the invention

[0119] A benzisoxazole of formula (I) or a pharmaceutically acceptable salt thereof: may be prepared as described in WO / 2016 / 097144 (US9932328).

[0120] For example, the following synthetic strategy may be implemented:

[0121] LCMS Methods

[0122] LCMS Method I

[0123] Agilent 1200-6110,

[0124] Signal table: Signal A: 214 nm, Signal B: 254 nm Column Temperature: 40°C

[0125] Column: HALO C18 4.6*50 mm, 2.7 pm

[0126] Intermediate 1: 1 -Chi oro-2, 4-dimethoxybenzene

[0127] To 4-chlororesorcinol (100 g, 691.8 mmol) in acetone (1000 mL), was added potassium carbonate (286.4 g, 2075.3 mmol) and the reaction mixture stirred at room temperature for 30 min. Dimethyl sulphate (500 mL) was added; the mixture was heated to 60 °C and stirred for 16 h. The mixture was filtered and the filtrate concentrated to afford 1 -chi oro-2, 4- dimethoxybenzene as a yellow oil (124 g, crude).

[0128] 1 H NMR (300 MHz, CDC13) 6 7.23 (s, 1 H), 6.51 (d, J = 2.7 Hz, 'H), 6.43 (dd, J = 8.7, 2.7 Hz, 1 H), 3.88 (s, 3H), 3.80 (s, 3H)].

[0129] Intermediate 2: 4-(5-Chloro-2,4-dimethoxyphenyl)-4-oxobutanoic acid

[0130] To 1 -chi oro-2, 4-dimethoxybenzene (for example as prepared for Intermediate 1, 124 g, 691.8 mmol) in DCM (1000 mL), was added succinic anhydride (76.2 g, 760.98 mmol) at 0 °C. Aluminium chloride (120 g, 899.34 mmol) was added also at 0 °C, the reaction mixture was warmed to room temperature and stirred for 30 min. The mixture was poured into ice-water (1000 mL), filtered and dried to afford 4-(5-chl oro-2, 4-dimethoxyphenyl)-4-oxobutanoic acid as a white solid (127 g).

[0131] LCMS (Method I): Rt =1.40 min, [M+H]+273.

[0132] Intermediate 3: Methyl 4-(5-chloro-2,4-dimethoxyphenyl)-4-oxobutanoate

[0133] To 4-(5-chloro-2,4-dimethoxyphenyl)-4-oxobutanoic acid (for example as prepared for Intermediate 2, 127 g, 465.7 mmol) in MeOH (500 mL), was added thionyl chloride (66.5 g, 558.8 mmol) at 0 °C. The reaction mixture was warmed to room temperature and stirred for 16 h. The solvent was removed, water (500 mL) was to the residue and the mixture extracted with DCM (500 mL x 3). The combined organic phases were dried over sodium sulphate and purified by silica gel column chromatography [silica, 200-300 mesh, 1000 g, eluted with petroleum ether / ethyl acetate 4: 1 to DCM / MeOH 100: 1] to afford methyl 4-(5-chloro-2,4- dimethoxyphenyl)-4-oxobutanoate as a pink solid (120.4 g).

[0134] LCMS (Method I): Rt =1.54 min, [M+H]+287.

[0135] Intermediate 4: Methyl 4-(5-chloro-2-hydroxy-4-methoxyphenyl)-4-oxobutanoate

[0136] To methyl 4-(5-chloro-2,4-dimethoxyphenyl)-4-oxobutanoate (for example as prepared for Intermediate 3, 120.4 g, 420 mmol) in MeCN (800 mL), was added sodium iodide (93.9 g, 630 mmol) and aluminium chloride (56 g, 420 mmol). After the addition the mixture was poured into ice-water (1000 mL) and extracted with ethyl acetate (600 mL x 4). The combined organic phases were concentrated and purified with silica gel column chromatography [silica, 200-300 mesh, 500 g, eluted with petroleum ether / ethyl acetate 5: 1 to DCM / MeOH 100:1] to afford methyl 4-(5-chloro-2-hydroxy-4-methoxyphenyl)-4- oxobutanoate as a yellow solid (95.3 g).

[0137] LCMS (Method I): Rt =1.57 min, [M+H]+273.

[0138] Intermediate 5: Methyl 4-(5-chloro-2-hydroxy-4-methoxyphenyl)-4-

[0139] To methyl 4-(5-chloro-2-hydroxy-4-methoxyphenyl)-4-oxobutanoate (for example as prepared for Intermediate 4, 95.3 g, 272.68 mmol) in pyridine / MeOH (1 :1, 500 mL), was added hydroxylamine hydrochloride (72.6 g, 1044.6 mmol) and the reaction mixture was stirred at 100 °C for 16 h. The solvent was removed, water (500 mL) was added to the residue and the mixture extracted with DCM (500 mL x 3). The solvent was removed from the combined organic phases and the residue purified with silica gel column chromatography [silica, 200-300 mesh, 500 g, eluted with DCM:MeOH 100: 1] to afford methyl 4-(5-chloro-2- hydroxy-4-methoxyphenyl)-4-(hydroxyimino)butanoate as a yellow solid (50 g).

[0140] LCMS (Method I): Rt =1.48 min, [M+H]+288.

[0141] Intermediate 6: Methyl 3-(5-chloro-6-methoxybenzo[d]isoxazol-3-yl)propanoate

[0142] Methyl 4-(5-chloro-2-hydroxy-4-methoxyphenyl)-4-(hydroxyimino)butanoate (for example as prepared for Intermediate 5, 53.4 g, 185.6 mmol) was added to pyridine / acetic anhydride (1 : 1, 500 mL) and the reaction mixture was stirred at 1 10 °C for 16 h, and then at 120 °C for 16 h. The solvent was removed and the residue was purified with silica gel column chromatography [silica, 200-300 mesh, 500 g, eluted with petroleum ether / ethyl acetate 5: 1 to DCM / MeOH 100: 1] to afford 2 batches of methyl 3-(5-chloro-6-methoxybenzo[d]isoxazol- 3-yl)propanoate (purple solid, 20 g) and (white solid, 9 g).

[0143] LCMS (Method I): Rt =1.53 min, [M+H]+270 for both batches.

[0144] Intermediate 7: Methyl 3-(5-chloro-6-hydroxybenzo[d]isoxazol-3-yl)propanoate

[0145] To methyl 3-(5-chloro-6-methoxybenzo[d]isoxazol-3-yl)propanoate (for example as prepared for Intermediate 6, 29 g, 107.53 mmol) in DCM (500 mL), was added aluminium chloride (72 g, 537.7 mmol ) at room temperature and the reaction mixture was stirred at room temperature for 16 h. The mixture was poured into ice / water (500 mL), extracted with DCM (400 mL x 3) and dried over sodium sulphate. The solvent was removed and the residue purified with silica gel column chromatography [silica, 200-300 mesh, 200 g, eluted with DCM / petroleum ether 1 :1 to DCM / ethyl acetate 100:3] to afford 3-(5-chloro-6- hydroxybenzo[d]isoxazol-3- yl)propanoate as a yellow solid (22 g).

[0146] LCMS (Method I): Rt =1.39 min, [M+H]+256.

[0147] Intermediate 8: 6-Methyl-2-tosyl-2,3-dihydropyridazine-3-carbonitrile

[0148] A solution of 3-methylpyridazine (47 g, 500 mmol) in DCM (500 mL), was added trimethylsilyl cyanide (90 g, 900 mmol) and aluminium chloride (0.4 g) and the mixture stirred at room temperature for 30 min. / ?-Toluenesulfonyl chloride (163.8 g, 900 mmol) in DCM was added drop-wise at room temperature and the reaction mixture stirred at room temperature for 16 h. The solvent was evaporated and the residual solid washed with ethanol (300 mL) to afford 6-methyl-2-tosyl-2,3-dihydropyridazine-3 -carbonitrile as a white solid (1 15 g).

[0149] 1H NMR (300 MHz, CDC13) 8 7.95 (d, J = 8.4 Hz, 2H), 7.37 (d, J = 8.0 Hz, 2H), 6.23 (dd, J = 9.2, 6.7 Hz, 1 H), 6.14 - 6.06 (m, 1 H), 5.70 (d, J = 6.7 Hz, 1 H), 2.46 (s, 3H), 2.15 (s, 3H).

[0150] Intermediate 8a (Intermediate 8 alternative preparation): 6-methyl-2-tosyl-2,3- dihydropyridazine-3-carbonitrile

[0151] To a solution of 3-methylpyridazine (289 g, 3.07 mol) in DCM (4 L), was added trimethylsilyl cyanide (368 g, 3.68 mol) and aluminium chloride (2.5 g, 18.8 mmol) and the reaction mixture was stirred at room temperature for 30 min. / ?-Toluenesulfonyl chloride (670 g, 3.68 mol) was added in portions at room temperature and the reaction stirred at room temperature for 3 h. The solvent was evaporated and the solid was washed with ethanol (2 L) to give 6-methyl-2-tosyl-2,3-dihydropyridazine-3-carbonitrile as a white solid (688 g).

[0152] 'HNMR (300 MHz, CDCI3) 6 7.95 (d, J = 8.3 Hz, 2H), 7.37 (d, J = 8.1 Hz, 2H), 6.23 (dd, J = 9.2, 6.7 Hz, 1 H), 6.10 (d, J = 9.2 Hz, 1 H), 5.70 (d, J = 6.7 Hz, 1 H), 2.46 (s, 3H), 2.14 (s, 3H); LCMS(A): Rt =1.47 min, MH+276.

[0153] Intermediate 9: 6-Methylpyridazine-3 -carbonitrile A solution of 6-methyl-2-tosyl-2,3-dihydropyridazine-3-carbonitrile (for example as prepared for Intermediate 8 1 15 g, 0.41 mol) in THF (1 L), was added 1 ,8-diazabicyclo[5.4.0]undec- 7-ene (75 g, 0.49mol) drop-wise at room temperature. The reaction mixture was stirred at room temperature for 2 h, the solvent evaporated and DCM (2 L) was added. The mixture was washed with water (1 L), dried and concentrated. The residue was purified with column chromatography [silica, 200-300 mesh, 500 g, eluted with petroleum ether / ethyl acetate 1 :2] to afford 6-methylpyridazine-3-carbonitrile as a yellow solid (37.6 g).

[0154] LCMS (Method I): Rt =0.93 min, [M+H]+120.

[0155] Intermediate 9a (Intermediate 9 alternative preparation): 6-methylpyridazine-3- carbonitrile

[0156] To a solution of 6-methyl-2-tosyl-2,3-dihydropyridazine-3-carbonitrile (688 g, 2.5 mol) in THF (3 L, anhydrous) was added dropwise 1 ,8-diazabicyclo[5.4.0]undec-7-ene (400 g, 2.63 mol) at room temperature and the reaction mixture was stirred at room temperature for 2 h. The solvent was evaporated and DCM (3 L) was added to the residue. The mixture was washed with water (2 L), dried with magnesium sulfate and the solvent evaporated. The residue was purified with column chromatography (silica, 2 Kg, eluted with petroleum ether / ethyl acetate 1 : 1) to give 6-methylpyridazine-3-carbonitrile as a yellow solid (228 g).

[0157] ‘HNMR (300 MHz, CDC13) 8 7.74 (d, J = 8.6 Hz, 1 H), 7.52 (d, J = 8.6 Hz, 1 H), 2.86 (s, 3H); LCMS(Method I): Rt =1 .01 min, MH+120.

[0158] Intermediate 10: l-(6-Methylpyridazin-3-yl)ethenone To a solution of 6-methylpyridazine-3-carbonitrile (for example as prepared for Intermediate 9, 28 g, 250 mmol) in toluene (300 mL) and diethyl ether (300 mL), was added methyl magnesium bromide (3M in ether, 208 ml, 625 mmol) drop-wise at -10 °C. The reaction mixture was stirred at 0 °C for 2 h. Hydrochloric acid (2 / V, 400 mL) was added and stirred at 0 °C for 15 min., then the aqueous phase was basified with sodium bicarbonate. The mixture was extracted with DCM (500 mL x 3), dried and evaporated. The residue was purified by flash chromatography [silica, 200-300 mesh, 500 g, eluted with petroleum ether / ethyl acetate 2: 1] to afford l-(6-methylpyridazin-3-yl)ethanone as a brown solid (20 g).

[0159] LCMS (Method I): Rt =1.08 min, [M+H]+137.

[0160] Intermediate 10a (Intermediate 10 alternative preparation): l-(6-methylpyridazin-3- yl)ethenone

[0161] To a solution of 6-methylpyridazine-3-carbonitrile (228 g, 1.92 mol) in toluene (2 L, anhydrous) and diethyl ether (2 L, anhydrous) was added methyl magnesium bromide (3M in ether, 0.77 L, 2.3 mol) dropwise at -10 °C under nitrogen. The reaction mixture was stirred at 0 °C for 1 h and quenched by addition of hydrochloric acid (27V, 2 L). The aqueous phase was separated and adjusted to pH 7-8 with sodium bicarbonate (solid). The aqueous phase was extracted with DCM (2 L x 3), dried with magnesium sulfate and evaporated. The residue was purified by column chromatography (silica: 100-200 mesh, 2 Kg, eluted with petroleum ether / ethyl acetate 1 : 1) to afford l-(6-methylpyridazin-3-yl)ethanone as a brown solid (151 g, 58%).

[0162] 'HNMR (300 MHz, CDC13) 8 8.02 (d, J = 8.6 Hz, 1 H), 7.48 (d, J = 8.6 Hz, 1 H), 2.87 (s, 3H), 2.81 (s, 3H); LCMS (Method I): Rt =1.1 1 min, MH+137.

[0163] A portion of this material (70 g, 515 mmol) was dissolved in hydrochloric acid (2 N, 500 mL), the reaction mixture was stirred at room temperature for 2 h, then adjusted to pH 8 with sodium bicarbonate (solid). The mixture was extracted with DCM (500 mL x 3), dried with magnesium sulfate and the solvent evaporated to give l-(6-methylpyridazin-3-yl)ethanone as a brown solid (68 g).

[0164] 'HNMR (300 MHz, CDC13) 8 8.00 (d, J = 8.6 Hz, 1 H), 7.47 (d, J = 8.6 Hz, 1 H), 2.87 (s, 3H), 2.80 (s, 3H); LCMS (Method I): Rt =1.1 1 min, MH+137.

[0165] Intermediate 11: l-(6-Methylpyridazin-3-yl)ethanol

[0166] To a solution of l-(6-methylpyridazin-3-yl)ethanone (for example as prepared for Intermediate 10, 10 g, 73.5 mmol) in MeOH (50 ml), was added sodium borohydride (5.58 g, 147 mmol) at room temperature and the reaction mixture stirred at room temperature for 2 h. The solvent was evaporated and DCM was added. The mixture was filtered and the residue washed with DCM. The combined organic phases were evaporated and the residue purified with flash chromatography [silica, 200-300 mesh, 80 g, eluted with DCM / MeOH 20: 1] to afford l-(6-methylpyridazin-3-yl)ethanol as an oil (8.2 g).

[0167] LCMS (Method I): Rt =0.55 min, [M+H]+139.

[0168] Intermediate 12: l-(6-Methylpyridazin-3-yl)ethyl methanesulfonate

[0169] To a solution of 1 -(6-methylpyridazin-3-yl)ethanol (for example as prepared for Intermediate 11, 8.2 g, 59.4 mmol) in DCM (100 ml), was added triethylamine (7.2 g, 71 .3 mmol) and methanesulfonyl chloride (8.55 g, 59.4 mmol) and the reaction mixture stirred at room temperature for 2 h. The reaction was quenched with water (50 ml), extracted with DCM (50 mL x 3) and the combined organic phased dried and the solvent evaporated. The residue was purified by flash chromatography [silica; 200-300 mesh, 80 g, eluted with DCM / MeOH 20: 1] to afford l-(6-methylpyridazin-3-yl)ethyl methanesulfonate as a brown oil (9.8 g).

[0170] LCMS (Method I): Rt =1.16 min, [M+H]+217.

[0171] Intermediate 13: Methyl 3-(5-chloro-6-(l -(6-methylpyridazin-3- yl)ethoxy)benzo[d]isoxazol-3- yl)propanoate

[0172] To methyl 3-(5-chloro-6-hydroxybenzo[d]isoxazol-3-yl)propanoate (for example as prepared for Intermediate 7, 7.67 g, 30 mmol) and 1 -(6-methylpyridazin-3-yl)ethyl methanesulfonate (for example as prepared for Intermediate 12, 30 mmol) in MeOH (500 mL) was added potassium carbonate (8.28g, 60 mmol) and the reaction mixture was stirred at 70 ° C for 16 h. The solvent was evaporated and the residue purified by silica gel column chromatography [silica, 200-300 mesh, 150 g, eluted with DCM / ethyl acetate 10: 1] to obtain methyl 3-(5- chloro-6-(l-(6-methylpyridazin-3-yl)ethoxy)benzo[d]isoxazol-3-yl)propanoate as a white solid (8.5 g).

[0173] LCMS (Method I): Rt =1.48 min, [M+H]+376.

[0174] Intermediate 14: (R)-methyl 3-(5-chloro-6-(l-(6-methylpyridazin-3- yl)ethoxy)benzo[d]isoxazol-3-yl)propanoate

[0175]

[0176] To a solution of (S)-l-(6-methylpyridazin-3-yl)ethanol (20.7 g, 150 mmol) and methyl 3-(5- chloro-6-hydroxybenzo[d]isoxazol-3-yl)propanoate (38.2 g, 150 mmol) in THF (200 mL, anhydrous) and toluene (200 mL, anhydrous) was added diethyl azodicarboxylate (31 .3 g, 180 mmol) and triphenylphosphine (47.2 g, 180 mmol). The reaction mixture was stirred at room temperature for 3 hours, the volatiles evaporated and the residue purified by column chromatography (silica: 100-200 mesh, 1.5 Kg, eluted with DCM / ethyl acetate 5: 1) to give (R)-methyl 3-(5-chloro-6-(l-(6-methylpyridazin-3-yl)ethoxy)benzo[d]isoxazol-3- yl)propanoate as an off-white solid (49.5 g).

[0177] 'HNMR (300 MHz, CDC13) 8 7.65 (s, 1 H), 7.58 (d, J = 8.7 Hz, 1 H), 7.35 (d, J = 8.6 Hz, 1 H), 7.06 (s, 1 H), 5.86 (d, J = 6.4 Hz, 1 H), 3.71 (s, 3H), 3.20 (t, J = 7.3 Hz, 2H), 2.88 (t, J = 7.4 Hz, 2H), 2.74 (s, 3H), 1.84 (d, J = 6.5 Hz, 3H); LCMS (Method I): Rt =1 .43 min, MH+376.

[0178] Example la: (R)-3-(5-Chloro-6-(l-(6- methylpyridazin-3-yl)ethoxy)benzo[d]isoxazol-3- yl)propanoic acid

[0179] To a solution of methyl 3-(5-chloro-6-(l-(6-methylpyridazin-3-yl)ethoxy)benzo[d]isoxazol-3- yl)propanoate (for example as prepared for Intermediate 13, 8.5 g, 22.7 mmol) in THF (100 mL), was added lithium hydroxide (37V, 30 mL, 90.8 mmol) and the solution stirred at room temperature for 2 h. The solvent was evaporated, water (50 mL) was added and the pH adjusted to between pH 2-3 with hydrochloric acid (1 N). The solid was isolated by filtration and dried in air to give a white solid. This solid was purified by chiral-prep-HPLC [SFC, column:chiralpak-IC,CO2-MeOH (formic acid)] to obtain (R)-3-(5-chloro-6-(l-(6- methylpyridazin-3-yl)ethoxy)benzo[d]isoxazol-3-yl)propanoic acid as an off-white solid (3.57 g)-

[0180] LCMS (Method I): Rt =1.37 min, [M+H]+362.1 HNMR (300 MHz, d6-DMSO) 5 12.29 (s, 1 H), 8.08 (s, 1 H), 7.68 (d, J = 8.7 Hz, 1 H), 7.60 (d, J = 8.8 Hz, 1 H), 7.48 (s, 1 H), 6.03 (dd, J = 12.7, 6.3 Hz, 1 H), 3.12 (t, J = 7.2 Hz, 2H), 2.73 (t, J = 7.2 Hz, 2H), 2.60 (s, 3H), 1.73 (d, J = 6.4 Hz, 3H). HPLC: 214 nm 98.9%, 254 nm 99.5%.

[0181] Example lb (alternative preparation): (R)-3-(5-chloro-6-(l-(6- methylpyridazin-3- yl)ethoxy)benzo[d]isoxazol-3-yl)propanoic acid

[0182] To (R)-3-(5-chloro-6-(l -(6-methylpyridazin-3-yl)ethoxy)benzo[d]isoxazol-3-yl)propanoic acid (79.5 g , 220 mmol, ee 89.5%) in MeCN (2 L), L(+)-arginine (38.3 g, 220 mmol) was added and the reaction mixture was stirred at 55 °C for 0.5 h. The mixture was cooled to room temperature, the solid was filtered and washed with MeCN (200 mL) and dried in air to give a white solid. The solid was added to hydrochloric acid (37%, 1 .5 L), and stirred at room temperature for 1 h, filtered and the solid washed with water (500 mL x 3) and dried in air to give (R)-3-(5-chloro-6-(l-(6-methylpyridazin-3-yl)ethoxy)benzo[d]isoxazol-3-yl)propanoic as a white solid, (68 g, ee 100%).

[0183] 'HNMR (400 MHz, d6-DMSO) 5 12.29 (s, 1 H), 8.09 (s, 1 H), 7.70 (d, J = 8.7 Hz, 1 H), 7.61 (d, J = 8.7 Hz, 1 H), 7.49 (s, 1 H), 6.04 (q, J = 6.4 Hz, 1 H), 3.13 (t, J = 7.3 Hz, 2H), 2.74 (t, J = 7.3 Hz, 2H), 2.61 (s, 3H), 1.74 (d, J = 6.4 Hz, 3H); LCMS (Method I): Rt =1 .36 min, MH+362.

[0184] Example 1c (alternative preparation): (R)-3-(5-chloro-6-(l-(6- methylpyridazin-3- yl)ethoxy)benzo[d]isoxazol-3-yl)propanoic acid

[0185] To a solution of (R)-methyl 3-(5-chloro-6-(l-(6-methylpyridazin-3- yl)ethoxy)benzo[d]isoxazol- 3-yl)propanoate (87 g, 231 .5 mmol) in THF (500 mL) was added lithium hydroxide (2N in water, 462 mL), the reaction mixture was stirred at room temperature for 4 hours, the organic solvent was evaporated and the residual aqueous phase washed with ethyl acetate (500 mL x 3). The aqueous phase was acidified with hydrochloric acid (27V) to pH = 2-3, the solid was isolated by filtration and washed with water (300 mL x 3). The solid was air dried to give (R)-3-(5-chloro-6-(l -(6-methylpyridazin-3- yl)ethoxy)benzo[d]isoxazol-3-yl)propanoic as a light-yellow solid (76 g, 92%, ee 89.5%).

[0186] 'HNMR (300 MHz, d6-DMSO) 5 12.28 (s, 1 H), 8.08 (s, 1 H), 7.70 (d, J = 8.7 Hz, 1H), 7.61 (d, J = 8.7 Hz, 1 H), 7.48 (s, 1 H), 6.03 (q, J = 6.3 Hz, 1 H), 3.13 (t, J = 7.2 Hz, 2H), 2.74 (t, J = 7.2 Hz, 2H), 2.61 (s, 3H), 1.74 (d, J = 6.4 Hz, 3H); LCMS(Method I): Rt =1.40 min, MH+362.

[0187] Synthesis of Compound 1: (R)-3-(5-chloro-6-(l-(6- methylpyridazin-3- yl)ethoxy)benzo[d]isoxazol-3-yl)propanoic acid, tris(hydroxymethyl) aminomethane

[0188] A solution of (R)-3-(5-chloro-6-(l-(6- methylpyridazin-3-yl)ethoxy)benzo[d]isoxazol-3- yl)propanoic acid (for example as prepared for Example la-c or as via the methods described in WO / 2016 / 097144) (0.20 mmol ) and tris (hydroxymethyl) aminomethane (24 mg, 0.20 mmol) in methanol (10 mL) was heated at 60°C for 2 h. After 2 h, the reaction mixture was concentrated under reduced pressure to afford a semi-solid, which was then triturated with diethyl ether (10 mL) to afford (R)-3-(5-chloro-6-(l-(6- methylpyridazin-3- yl)ethoxy)benzo[d]isoxazol-3-yl)propanoic acid, tris(hydroxymethyl) aminomethane salt as an off-white solid.

[0189] Example 2 - Dose prediction in humans using scaling from preclinical species

[0190] Prior to administration of Compound 1 in humans pharmacokinetic (PK) parameters in humans were estimated from preclinical PK data in rats and dogs using standard species scaling. The predicted human PK parameters, scaled from rat and dog are shown in Table 1.

[0191] Table 1. Predicted pharmacokinetic parameters for Compound 1 scaled from rat and dog.

[0192] Parameter Units Scaled From Rat Scaled From Dog

[0193] CL L / hour 5 23

[0194] VdL 31 63 k l / hour 0.16 0.37 t% hour(s) 4 2

[0195] Abbreviations: CL, total body clearance; k, elimination rate constant; ti / 2, half-life; Va, volume of distribution.

[0196] A direct relationship between Compound 1 plasma concentration and reduction in plasma 3HK due to KMO inhibition was assumed to set the starting dose for Part A (Single dose administration). Based on in vitro cellular assays and in vivo measurements of the relationship between drug plasma concentration and 3HK levels, the predicted half maximal inhibitory concentration (ICSO,3HK) in human plasma was estimated to be between approximately 1 ng / mL and of 15 ng / ml. Percentage inhibition (% reduction in plasma 3HK), was calculated using the equation given below: 100 A comparison of predicted inhibition at a dose of 1000pg / 0.5h, using the different PK and ICSO.SHK parameters described above, is shown in Table 2.

[0197] Table 2. Predicted KMO inhibition at Cmax following 1000pg / 0.5h dose.

[0198] Plasma ICSO,3HK

[0199] Species Scaling Cmax (ng / ml) Inhibition (%)

[0200] (ng / ml)

[0201] Dog 14 15 49

[0202] Dog 14 1 93

[0203] Rat 32 15 68

[0204] Rat 32 1 97

[0205] Note: Cmaxwas calculated using the following equation:

[0206] Cmax=— ~ — X (1 — e-fcXT) , where D is dose, V is volume of distribution, T is the infusion period and k is the elimination rate constant.

[0207] A starting dose of 5pg / 0.5h was chosen as the starting dose for Part A (Single dose administration) in humans. Assuming PK scaled from rat and a plasma ICSO,3HK = 1 ng / ml the maximum reduction in plasma 3HK at Cmax at a dose of 5pg / 0.5h would be 13%.

[0208] Example 3 - Part A (Single dose administration)

[0209] Study Protocol

[0210] Part A (Single dose administration) was a randomised, double-blind, placebo-controlled, single ascending dose (SAD) study with a 2-cohort, partial crossover design. Participants were to be enrolled sequentially into 1 of 2 cohorts (6 participants per cohort, not including replacements).

[0211] Participants enrolled in Cohort Al were randomly assigned (in a 1 : 1 : 1 ratio) to 1 of 3 treatment sequences, where each treatment sequence had 3 treatment periods and started with either 5 pg Compound 1 or placebo, followed by 2 additional treatment periods, each with a higher dose level of Compound 1 or placebo, as follows:

[0212] Participants enrolled in Cohort A2 were randomly assigned (in a 1 : 1 : 1 ratio) to 1 of 3 treatment sequences, where each treatment sequence had 3 treatment periods and started with either 200 pg Compound 1 or placebo, followed by 2 additional treatment periods, each with a higher dose level of Compound 1 or placebo, as follows:

[0213] For each participant in Part A, the study consisted of a screening period, 3 treatment periods, and an end-of-study (EOS) visit.

[0214] On Day 1 of each period, participants received a single dose of Compound 1 or placebo, administered as a single IV infusion.

[0215] Compound 1 was administered as a single IV infusion, administered over approximately 30 minutes in Part A; the following dose levels were administered: 5, 20, 70, 200, 600, and 1000 Pg-

[0216] The saline placebo was administered as a single IV infusion, administered over approximately 30 minutes.

[0217] Results

[0218] A total of 16 participants were screened, randomised, and dosed. Of the 16 participants, 12 participants (75%) were treated in each of Period 1, Period 2, and Period 3. All participants in Sequence 1, Sequence 3, and Sequence 6 completed Part A of the study. In Sequence 2 and Sequence 4, 2 participants (66.7%) each completed Part A of the study and 1 participant (33.3%) each discontinued from the study and were replaced.

[0219] In Sequence 5, 2 participants (50.0%) completed Part A of the study and 2 participants (50.0%) discontinued from the study.

[0220] Pharmacokinetic properties of Part A (single dose administration)

[0221] PK parameters (Table 3) were calculated using standard non-compartmental analysis. Sufficient data points were only available at 600 and lOOOpg doses to determine the full range of PK parameters.

[0222] The Cmax of Compound 1 was achieved at a median Tmax value of approximately 0.5 hours for all dose levels except the 5 pg dose level, where Compound 1 levels were below the limit of quantification at all time points.

[0223] The plasma concentrations of Compound 1 declined over time after Tmax, with arithmetic mean half-lives (ti / 2,z) of 2.15 hours and 3.45 hours for the 600 pg and 1000 pg dose levels, respectively. For the other dose levels, the apparent half-lives could not be reliably estimated. Plasma concentrations vs time profiles are shown in Figure 1.

[0224] The mean volume of distribution ranged from 37.3 L to 26.6 L, and the mean clearance ranged from 15.6 L / h to 6.19 L / h for the 600 pg and 1000 pg dose levels, respectively.

[0225] Reliable estimates for clearance and volume of distribution could not be obtained for the other dose levels.

[0226] Between the 70 pg and 1000 pg dose levels, the values of the exponent for AUCo-t and Cmaxwere 1.239 (90% confidence interval [CI]: 1.126, 1.352) and 2.132 (90% CI: 1.902, 2.361), respectively, indicating a greater than dose-proportional relationship for AUCo-t and Cmax.

[0227] Table 3. Geometric mean calculated PK parameters at each dose in Part A (Single dose administration). Dose Cmax AUCo-t t' / 2CL Vss

[0228] Cohort

[0229] (pg) (ng / ml) (h.ng / ml) (h) (L / h) (L)

[0230] 5 NA NA NA NA NA

[0231] Al 20 NA NA NA NA NA

[0232] 70 1.74 0.53 NA NA NA

[0233] 200 5.40 2.48 NA NA NA

[0234] A2 600 20.6 33.4 2.15 15.6 37.3

[0235] 1000 49.8 153 3.45 6.19 26.6

[0236] Abbreviations: NA - not applicable; insufficient concentration data for parameter estimation.

[0237] Example 4 - Part B (Intravenous infusion)

[0238] Study Protocol

[0239] Part B (Intravenous infusion) was a randomised, double-blind, placebo-controlled, multiple ascending dose (MAD) study. In this part of the study, 3 dose cohorts (up to 8 participants per cohort, not including replacements) were planned.

[0240] Within each cohort, participants were randomly assigned to receive Compound 1 or placebo (in a 6:2 ratio), administered as an IV loading dose on Day 1 immediately followed by continuous IV infusion over 7 days.

[0241] Compound 1 was administered as an IV loading dose, administered over approximately 30 minutes, followed by continuous IV infusion over 7 days in Part B. The following dose levels were administered:

[0242] • Cohort Bl (Treatment 60 pg Compound 1): 60 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 40 pg / h Compound 1 continuous IV infusion over 7 days

[0243] • Cohort B2 (Treatment 120 pg Compound 1): 120 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 80 pg / h Compound 1 continuous IV infusion over 7 days

[0244] • Cohort B3 (Treatment 360 pg Compound 1): 360 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 240 pg / h Compound 1 continuous IV infusion over 7 days

[0245] Matching placebo administered as a single IV infusion, administered as an IV loading dose, over approximately 30 minutes, followed by continuous IV infusion over 7 days (Part B). Results

[0246] A total of 24 participants (8 participants in each of the 3 cohorts) were screened, randomised, and dosed in accordance with the protocol. All participants completed Part B of the study.

[0247] Pharmacokinetic properties of Part B (Intravenous infusion)

[0248] Doses were administered as an initial bolus infusion over 30 minutes followed by constant infusion over 7 days. PK parameters (Table 4) were calculated using non-compartmental analysis.

[0249] Following the IV loading dose given over 0.5-hour at 60 pg, 120 pg, and 360 pg of Compound 1, and respective continuous IV infusion for 167.5 hours at 40 pg / h, 80 pg / h, and 240 pg / h, the geometric mean Cmax was 18.6, 37.6 and 95.6 ng / mL, respectively. The overall exposure, as measured by the geometric mean AUCO-t was 1890, 4170, and 11900 h*ng / mL following a respective continuous IV infusion at 40 pg / h, 80 pg / h, and 240 pg / h and the exposure over the infusion period (AUCO-168) was 1870, 4410, and 11700 h*ng / mL.

[0250] The geometric mean Cssof Compound 1 was 11.9, 25.6, and 74.2 ng / mL following respective continuous IV infusions at 40 pg / h, 80 pg / h, and 240 pg / h.

[0251] The estimated values of the exponent of the slopes for Cmax, Css, AUCo-ies, and AUCo-t indicated a dose-proportional relationship in the extent of systemic exposure over this dose range.

[0252] Table 4. Geometric mean calculated PK parameters at each dose in Part B (Intravenous infusion).

[0253] Dose Css AUCo-t t> / 2CL Vss

[0254] Cohort

[0255] (Pg) (ng / ml) (h.ng / ml) (h) (L / h) (L)

[0256] Bl 60 11.9 1890 2.56 3.36 12.4

[0257] B2 120 25.6 4170 4.13 3.13 18.6

[0258] B3 360 74.2 11900 4.66 3.24 21.8 Note: Treatment 60 pg Compound 1 : 60 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 40 pg / h Compound 1 continuous IV infusion over 7 days; Treatment 120 pg: 120 ug / O.5h Compound 1 IV loading dose on Day 1 immediately followed by 80 pg / h Compound 1 continuous IV infusion over 7 days, Treatment 360 pg Compound 1 : 360 pg / 0.5h Compound 1 IV loading dose on Day 1 immediately followed by 240 pg / h Compound 1 continuous IV infusion over 7 days.

[0259] Plasma concentrations at steady state were higher than predicted from Part A (Single dose administration) due to lower than expected values for CL. However, CL was not markedly different at each of the doses tested in Part B. The Csswas higher than the concentration at the end of the initial 30 minute bolus infusion, suggesting that clearance and volume of distribution may vary with dose. This is exemplified by the concentration vs time profiles shown in Figure 2.

[0260] Example 5 - Pharmacodynamics of Part A (Single dose administration) and Part B (Intravenous infusion)

[0261] Preclinical data demonstrated that inhibition of KMO in vivo reduces the plasma 3HK level and increases the levels of both KYN and KYNA. As noted above, there was some uncertainty regarding the in vivo ICSO,3HK of KMO in humans predicted by preclinical data. KYN, KYNA and 3HK levels were measured at each dose level to determine the degree of pharmacodynamic inhibition in humans.

[0262] In Part A, there was a dose-dependent effect of Compound 1 on KYN and KYNA, with increasing doses leading to an increased percent change from baseline (Emax) and AUEC from time 0 to the last quantifiable concentration (AUECaii). 3HK was observed to decrease dose- dependently, based on percent change from baseline (Emin), in comparison with placebo at the 600 pg and 1000 pg dose levels.

[0263] In Part A (Single dose administration), reductions in 3HK were evident at doses above 200pg / 0.5h with a maximal reduction compared to baseline (Emin) of -44.8% and -50.9% at 600pg / 0.5h and 1000pg / 0.5h respectively (Figure 3). The degree of 3HK reduction at lower doses could not be determined due to large variations in the measured 3HK levels. KYN and KYNA increased in a dose-dependent manner with Emax for KYN and KYNA increasing to 709% and 4100% at lOOOpg when compared to baseline (Figure 3). A comparison of the PK / PD data for Part A (Single dose administration) with the predicted PK / PD in Table 2 shows that preclinical data overestimates the reduction in plasma 3HK at a given Cmax, regardless of which value of ICSO.SHK was used to calculate inhibition (Table 5). This suggests that a more complex relationship between PK and PD occurs in humans, which could not have been predicted based on standard PK / PD modelling of preclinical data.

[0264] In Part B, Participants receiving Compound 1 demonstrated substantially higher levels of KYN and KYNA compared to the placebo group. The Emaxand area under the PD effect curve (AUECaii) values for KYN and KYNA, based on percent change from baseline, were also substantially higher for Compound 1 compared to placebo at all dose levels.

[0265] Participants receiving Compound 1 had substantially lower levels of 3HK compared to the placebo group. The Emin and area under the PD effect curve (AUECaii) values for 3HK, based on percent change from baseline, were substantially lower (ie, more negative) for Compound 1 compared to placebo at all dose levels and reduced dose-dependently.

[0266] In Part B (Intravenous infusion), steady state inhibition of KMO was established at all three dose levels with reductions in 3HK relative to baseline (Emin) of -40.9, -61.2 and -78.3% at 60pg / 0.5h followed by 40pg / h, 120pg / 0.5h followed by 80pg / h and 360pg / 0.5h followed by 240pg / h doses respectively (Figure 4).

[0267] For KYN, the mean maximum percentage change from baseline (Emax) values were observed to be substantially higher in the participants receiving Compound 1 compared to placebo. The average Emax values, were 1230%, 1220%, and 1190% for each of the respective doses of Compound 1, compared to 54.6 % for KYN in the placebo group (Figure 5).

[0268] Similarly, KYNA Emax levels were substantially higher in participants receiving Compound 1 compared to the placebo group. The average Emax values, based on percent change from baseline, were 5440%, 4900%, and 4890% for each of the respective doses of Compound 1, compared to 42.6% for KYNA in the placebo group (Figure 5). The data demonstrate robust, dose-dependent inhibition of KMO.

[0269] Example 6 - Prediction ofPK / PD

[0270] Table 5 shows the predicted values of Csscalculated from the CL observed in Part A, where

[0271] Table 5. Predicted Cssbased on PK from Part A (Single dose administration), and actual PK for Part B (Intravenous infusion).

[0272] Dose CL Predicted Css Actual Css

[0273] (ug / h) (L / h) (ng / mL) (ng / mL)

[0274] 40 15.6 2.6 11.9

[0275] 80 15.6 5.1 25.6

[0276] 240 15.6 15.4 74.2

[0277] 40 6.19 6.5 11.9

[0278] 80 6.19 12.9 25.6

[0279] 240 6.19 38.8 74.2

[0280] At each of the dose levels in Part B, the Csscalculated from CL values observed in Part A was lower than expected, based on the relationship between infusion rate and observed CL in Part A. This represents an unexpectedly higher Csslevels as a result of the dosing regimen described herein.

[0281] The following are numbered aspects of the invention:

[0282] 1. A compound for use in a method of treating or preventing a KMO mediated disorder in a subject in need thereof; wherein said compound is a benzisoxazole of formula (I) or a pharmaceutically acceptable salt thereof: wherein said method comprises administering said compound to the subject as an intravenous infusion at a dose rate of between about 200 pg / h and about 2.5 mg / h over a period of at least 12 hours.

[0283] 2. The compound for use of aspect 1, wherein the subject is human.

[0284] 3. The compound for use of aspect 1 or 2 wherein said intravenous infusion has a dose rate of between about 240 pg / h and about 2.5 mg / h.

[0285] 4. The compound for use of aspect 3 wherein said intravenous infusion has a dose rate of between about 240 pg / h and about 2.25 mg / h.

[0286] 5. The compound for use of any one of aspects 1 to 4 wherein said intravenous infusion is administered for a period of between 1 and 14 days.

[0287] 6. The compound for use of any one of aspects 1 to 5 wherein said method additionally comprises administering a bolus at a dosage of between about 350 pg and about 20 mg of said compound. 7. The compound for use of aspect 6 wherein said bolus is administered at a dosage of between about 350 pg and about 18 mg of said compound.

[0288] 8. The compound for use of aspect 7 wherein said bolus is administered at a dosage of between about 350 pg and about 10 mg of said compound.

[0289] 9. The compound for use of aspect 8 wherein said bolus is administered at a dosage of between about 350 pg and about 6 mg of said compound.

[0290] 10. The compound for use of aspect 9 wherein said bolus is administered at a dosage of between about 350 pg and about 3 mg of said compound.

[0291] 11. The compound for use of any one of aspects 6 to 10 wherein said bolus is administered before the intravenous infusion.

[0292] 12. The compound for use of any one of aspects 6 to 11 wherein said bolus is administered as an intravenous injection.

[0293] 13. The compound for use of any one of aspects 6 to 11 wherein said method comprises administering said compound as:

[0294] (i) a bolus of between about 350 pg and about 20 mg; and subsequently

[0295] (ii) an intravenous infusion at a dose rate of about 240 pg / h and about 2.5 mg / h.

[0296] 14. The compound for use of any of aspects 6 to 11 wherein said method comprises administering a bolus infusion at a dose rate of between about 350 pg / h and about 80 mg / h, followed by a maintenance infusion at a dose rate of between about 200 pg / h and about 2.5 mg / h.

[0297] 15. The compound for use of aspect 14 wherein the maintenance infusion is at a dose rate of between about 240 pg / h and about 2.5 mg / h. 16. The compound for use of aspect 15 wherein the maintenance infusion is at a dose rate of between about 240 pg / h and about 2.25 mg / h.

[0298] 17. The compound for use of any one of aspects 14 to 16, wherein the bolus infusion is administered for a period of up to 1 hour and the maintenance infusion is administered for a period of between 1 and 14 days.

[0299] 18. The compound for use of any one of the preceding aspects wherein said method provides a reduction of plasma 3 HK levels in the subject of at least 75% compared to baseline.

[0300] 19. The compound for use of aspect 18 wherein said method provides a reduction of plasma 3 HK levels in the subject of at least 80% compared to baseline.

[0301] 20. The compound for use of aspect 19 wherein said method provides a reduction of plasma 3 HK levels in the subject of at least 85% compared to baseline

[0302] 21. The compound for use of aspect 20 wherein said method provides a reduction of plasma 3 HK levels in the subject of at least 90% compared to baseline.

[0303] 22. The compound for use of aspect 21 wherein said method provides a reduction of plasma 3HK levels in the subject of at least 95% compared to baseline.

[0304] 23. The compound for use of any one of the preceding aspects wherein said method is a method of treating or preventing a KMO mediated disorder selected from the group consisting of: acute pancreatitis, chronic kidney disease, acute kidney disease, acute kidney injury, systemic inflammatory response syndrome (SIRS), sepsis, cardiovascular shock, severe trauma, acute lung injury, acute respiratory distress syndrome, acute cholecystitis, pneumonia, ischemic bowel disease, severe acute hepatic disease, severe acute hepatic encephalopathy or acute renal failure. 24. The compound for use of aspect 23 wherein said KMO mediated disorder is acute pancreatitis.

[0305] 25. The compound for use of aspect 24 wherein said KMO mediated disorder is severe acute pancreatitis.

[0306] 26. The compound for use of aspect 24 wherein said KMO mediated disorder is critical acute pancreatitis.

[0307] 27. The compound for use of aspect 23 wherein said KMO mediated disorder is acute kidney injury.

[0308] 28. The compound for use of any one of aspects 23 to 27 wherein said compound is administered to a subject who has undergone surgery.

[0309] 29. The compound for use of aspect 28 wherein said compound is administered to a subject who has undergone cardiac surgery.

[0310] 30. The compound for use of any one of aspects 23 to 27 wherein said compound is administered to a subject who is suffering from bums.

[0311] 31. The compound for use of any one of the preceding aspects wherein said subject has severe acute pancreatitis.

[0312] 32. The compound for use of any one of the preceding aspects wherein said subject has critical acute pancreatitis.

Claims

1. CLAIMS1. A compound for use in a method of treating or preventing a KMO mediated disorder in a human subject in need thereof; wherein said compound is a benzisoxazole of formula (I) or a pharmaceutically acceptable salt thereof:wherein said method comprises administering said compound to the subject as an intravenous infusion at a dose rate of between about 200 pg / h and about 2.5 mg / h over a period of at least 12 hours.

2. The compound for use of claim 1 wherein said intravenous infusion has a dose rate of between about 240 pg / h and about 2.5 mg / h; preferably between about 240 pg / h and about 2.25 mg / h.

3. The compound for use of claim 1 or claim 2 wherein said intravenous infusion is administered for a period of between 1 and 14 days.

4. The compound for use of any one of claims 1 to 3 wherein said method additionally comprises administering a bolus at a dosage of between about 350 pg and about 20 mg of said compound; preferably said bolus is administered at a dosage of between about 350 pg and about 18 mg; more preferably between about 350 pg and about 10 mg; further preferably between about 350 pg and about 6 mg of said compound; more further preferably between about 350 pg and about 3 mg of said compound.

5. The compound for use of claim 4 wherein said bolus is administered before the intravenous infusion.

6. The compound for use of claim 4 or 5 wherein said bolus is administered as an intravenous injection.

7. The compound for use of claim 4 or 5 wherein said method comprises administering said compound as:(i) a bolus of between about 350 pg and about 20 mg; and subsequently(ii) an intravenous infusion at a dose rate of about 240 pg / h and about 2.5 mg / h.

8. The compound for use of claim 4 or 5 wherein said method comprises administering a bolus infusion at a dose rate of between about 350 pg / h and about 80 mg / h, followed by a maintenance infusion at a dose rate of between about 200 pg / h and about 2.5 mg / h, preferably wherein the maintenance infusion is at a dose rate of between about 240 pg / h and about 2.5 mg / h; preferably between about 240 pg / h and about 2.25 mg / h.

9. The compound for use of claim 8, wherein the bolus infusion is administered for a period of up to 1 hour and the maintenance infusion is administered for a period of between 1 and 14 days.

10. The compound for use of any one of the preceding claims wherein said method provides a reduction of plasma 3HK levels in the subject of at least 75% compared to baseline.

11. The compound for use of claim 10 wherein said method provides a reduction of plasma 3HK levels in the subject of at least 80% compared to baseline; preferably of at least 85% compared to baseline; more preferably of at least 90% compared to baseline; and most preferably of at least 95% compared to baseline.

12. The compound for use of any one of the preceding claims wherein said method is a method of treating or preventing a KMO mediated disorder selected from the group consisting of: acute pancreatitis, chronic kidney disease, acute kidney disease, acute kidney injury, systemic inflammatory response syndrome (SIRS), sepsis, cardiovascular shock, severe trauma, acute lung injury, acute respiratory distress syndrome, acute cholecystitis, pneumonia,ischemic bowel disease, severe acute hepatic disease, severe acute hepatic encephalopathy or acute renal failure.

13. The compound for use of claim 12 wherein said KMO mediated disorder is acute pancreatitis.

14. The compound for use of claim 12 wherein said KMO mediated disorder is acute kidney injury.

15. The compound for use of any one of claims 12 to 14 wherein said compound is administered to a subject who:(a) has undergone surgery, in particular a subject who has undergone cardiac surgery; or(b) is suffering from bums.

Images