Treating hair loss disorders with deuterated JAK inhibitors

Abstract

A method of treating a JAK inhibition responsive state (such as a hair loss disorder) in a human subject in need thereof, comprising administering to the human subject a therapeutically effective amount of Compound (I), or a pharma- ceutical acceptable salt thereof, wherein each position specifically designated as deuterium has at least 95% deuterium incorporation, and wherein the subject is receiving concomitant administration of a CYP3A4 inhibitor, such that the therapeutically effective amount of Compound (I), or a pharma-ceutical acceptable salt thereof, is not decreased compared to the therapeutically effective amount of Compound (I), or a pharma-ceutical acceptable salt thereof, that would be administered to the subject in the absence of concomitant administration of a CYP3A4 inhibitor.

Description

[Background technology]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 232107, filed August 11, 2021, the entire teachings of which are incorporated herein by reference.

[0002] Patients often take multiple medications at once, which can result in drug-drug interactions. Drug-drug interactions occur when two or more drugs both interact with the same metabolic enzyme, altering the total exposure to the administered drugs and producing additional or more severe side effects. Drug-drug interactions can also occur when one drug inhibits the enzyme that metabolizes the second drug, thereby increasing the concentration of the second drug in the bloodstream, leading to an increased risk of side effects. Depending on the severity of the interaction, patients may need to change the dose of one or both drugs, or even discontinue use of one drug.

[0003] According to the FDA, unexpected or unrecognized drug-drug interactions are an important cause of morbidity and mortality associated with prescription drugs. The FDA has established guidelines for the conduct of drug-drug interaction studies to assist with drug labeling and limit adverse events caused by drug-drug interactions. For drugs metabolized by CYP 450 enzymes, the FDA provides a list of enzyme inhibitors for conducting clinical trials on drug-drug interactions. Ketoconazole and itraconazole are among the strong CYP3A4 inhibitors used for drug-drug interaction studies.

[0004] Ruxolitinib phosphate is a heteroaryl-substituted pyrrolo[2,3-d]pyrimidine, also known as 3(R)-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile phosphate, which inhibits the Janus-associated kinases (JAKs) JAK1 and JAK2. These kinases mediate the signal transduction of numerous cytokines and growth factors important for hematopoiesis and immune function. JAK signaling involves the recruitment of STATs (signal transducers and activators of transcription) to cytokine receptors, activation, and subsequent localization of STATs to the nucleus, leading to the regulation of gene expression.

[0005] Ruxolitinib phosphate is currently approved for the treatment of patients with intermediate-risk or high-risk myelofibrosis, including primary myelofibrosis, post-polycythemia vera myelofibrosis, and post-essential thrombocythemia myelofibrosis. Ruxolitinib phosphate is also currently in clinical trials for the treatment of additional conditions.

[0006] Ruxolitinib has known drug-drug interactions with strong CYP3A4 inhibitors. These interactions are severe enough that the prescribing information for ruxolitinib requires dose modifications for coadministration with strong CYP3A4 inhibitors, including boceprevir, clarithromycin, conivaptan, indinavir, itraconazole, ketoconazole, lopinavir / ritonavir, mibefradil, nefazodone, nelfinavir, posaconazole, ritonavir, saquinavir, telaprevir, telithromycin, and voriconazole.

[0007] The prescribing information for ruxolitinib describes a drug-drug interaction study in healthy volunteers in which subjects received ruxolitinib before and after taking ketoconazole. The study consisted of a single dose of 10 mg ruxolitinib on day 1, 200 mg ketoconazole twice daily on days 2-4, and 10 mg ruxolitinib + 200 mg ketoconazole on day 5. Combining ruxolitinib with ketoconazole resulted in a C-reactive protein of ruxolitinib. max increased by 33%, the AUC increased by 91%, and the half-life increased from 3.7 to 6.0 hours. These changes were significant and warrant a label caution regarding coadministration of ruxolitinib with strong CYP3A4 inhibitors.

[0008] Despite the beneficial activity of ruxolitinib, there continues to be a need for new compounds that inhibit JAK1 and JAK2 but are not adversely affected by concomitant administration of CYP3A4 inhibitors. Summary of the Invention

[0009] Compound (I), also known as (R)-3-(4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl)-3-(cyclopentyl-2,2,3,3,4,4,5,5-d8)propanenitrile, or D8-ruxolitinib), which is useful for the treatment of JAK inhibition responsive states, including hair loss disorders such as alopecia areata, has unexpectedly been found not to require dose adjustment or interruption of treatment when co-administered with a strong CYP3A4 inhibitor.

[0010] In a first embodiment, the invention relates to a method of treating a JAK inhibition responsive state (such as a hair loss disorder) in a human subject in need thereof, the method comprising administering to a subject a compound (I) represented by the following structural formula: [ka] or a pharma- ceutical acceptable salt thereof, Compound (I) each position specifically designated as deuterium has at least 95% deuterium incorporation; (i) The subject is receiving concomitant use of a CYP3A4 inhibitor, (ii) the therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof, is not decreased compared to the therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof, that would be administered to a subject in the absence of concomitant administration of a CYP3A4 inhibitor.

[0011] In a second embodiment, the invention relates to a method of treating a JAK inhibition responsive state (such as a hair loss disorder) in a human subject in need thereof, the method comprising administering to a subject a compound (I) represented by the following structural formula: [ka] or a pharma- ceutical acceptable salt thereof, wherein each position specifically designated as deuterium has at least 95% deuterium incorporation; Compound (I) (i) The subject is determined to be taking a CYP3A4 inhibitor concomitantly, (ii) the therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof, is not decreased compared to the therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof, that would be administered to a subject in the absence of concomitant administration of a CYP3A4 inhibitor.

[0012] In a third embodiment, the invention relates to a method of treating a JAK inhibition responsive state (such as a hair loss disorder) in a human subject in need of such treatment, the method comprising the steps of receiving information relating to whether the patient is concomitantly administered a CYP3A4 inhibitor; Compound (I) represented by the following structural formula: [ka] or a pharma- ceutical acceptable salt thereof, wherein each position specifically designated as deuterium has at least 95% deuterium incorporation; Compound (I) (i) the information indicates that the subject is taking a concomitant CYP3A4 inhibitor; (ii) the therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof, is not decreased compared to the therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof, that would be administered to a subject in the absence of concomitant administration of a CYP3A4 inhibitor.

[0013] In a fourth embodiment, the present invention relates to a method of treating a JAK inhibition responsive state (such as a hair loss disorder) in a human subject in need of such treatment, the method comprising the steps of: selecting a human subject based on the human subject's concomitant administration of a CYP3A4 inhibitor; Compound (I) represented by the following structural formula: [ka] or a pharma- ceutical acceptable salt thereof to a selected human subject, wherein each position specifically designated as deuterium has at least 95% incorporation of deuterium, and the therapeutically effective amount of Compound (I), or a pharma- ceutical acceptable salt thereof, is not decreased compared to the therapeutically effective amount of Compound (I), or a pharma- ceutical acceptable salt thereof, that would be administered to the subject in the absence of concomitant administration of a CYP3A4 inhibitor. Compound (I)

[0014] In a fifth embodiment, the present invention relates to a method of treating a JAK inhibition responsive state (such as a hair loss disorder) in a human subject in need of such treatment, the method comprising the steps of: obtaining a blood sample from a subject; determining a pre-dose level of a CYP3A4 inhibitor in a blood sample (i.e., before administration of Compound (I)); administering a therapeutically effective amount of a compound to a subject; pre-dose levels of a CYP3A4 inhibitor in the blood sample indicate that the subject is receiving concomitant administration of a CYP3A4 inhibitor; The compound is represented by the following structural formula (I): [ka] or a pharma- ceutically acceptable salt thereof, wherein each position specifically designated as deuterium has at least 95% deuterium incorporation; The therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof, is not decreased compared to the therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof, that would be administered to a subject in the absence of concomitant administration of a CYP3A4 inhibitor.

[0015] In a sixth embodiment, the invention relates to a method of treating a JAK inhibition responsive state (such as a hair loss disorder) in a human subject in need of such treatment, the method comprising: (i) determining whether the human subject is receiving a concomitant CYP3A4 inhibitor; and (ii) administering to a human subject a therapeutically effective amount of compound (I), wherein compound (I) is represented by the following structural formula: [ka] or a pharma- ceutically acceptable salt thereof, wherein each position specifically designated as deuterium has at least 95% deuterium incorporation; Compound (I) The therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof, is not decreased compared to the therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof, that would be administered to a subject in the absence of concomitant administration of a CYP3A4 inhibitor.

[0016] For any one of the first to sixth embodiments, in a first aspect, the JAK inhibition responsive state is a hair loss disorder that is alopecia areata.

[0017] In the second aspect of any one of the first to sixth embodiments, or in the first aspect thereof, Compound (I), or a pharma- ceutically acceptable salt thereof, is administered in an amount within the range of about 8 mg to about 32 mg per day.

[0018] In the third aspect of any one of the first to sixth embodiments, or the first or second aspects thereof, Compound (I), or a pharma- ceutically acceptable salt thereof, is administered at about 16 mg / day, or about 24 mg / day.

[0019] For any one of the first to sixth embodiments, in the fourth aspect, or the first, second, or third aspects thereof, about 16 mg / day of Compound (I), or a pharma- ceutically acceptable salt thereof, is administered as about 8 mg twice a day, and about 24 mg / day of the compound, or a pharma- ceutically acceptable salt thereof, is administered as about 12 mg twice a day.

[0020] For any one of the first to sixth embodiments, in the fifth aspect, or the first or second aspects thereof, about 8 mg / day of Compound (I), or a pharma- ceutically acceptable salt thereof, is administered at about 8 mg once a day, or at 4 mg twice a day.

[0021] In the sixth aspect of any one of the first through sixth embodiments, or the first, second, third, fourth, or fifth aspect thereof, Compound (I), or a pharma- ceutically acceptable salt thereof, is administered orally.

[0022] In a seventh aspect of any one of the first through sixth embodiments, or the first, second, third, fourth, fifth, or sixth aspects thereof, Compound (I), or a pharma- ceutically acceptable salt thereof, is administered in a pharmaceutical formulation that is a tablet.

[0023] In an eighth aspect of any one of the first to sixth embodiments, or in the first, second, third, fourth, fifth, sixth, or seventh aspect thereof, Compound (I), or a pharma- ceutically acceptable salt thereof, is administered to a human subject for at least 24 weeks.

[0024] In a ninth aspect of any one of the first to sixth embodiments, or the first, second, third, fourth, fifth, sixth, seventh, or eighth aspect thereof, in compound (I), each position specifically designated as deuterium has at least 97% deuterium incorporation.

[0025] In a tenth aspect of any one of the first to sixth embodiments, or the first, second, third, fourth, fifth, sixth, seventh, eighth, or ninth aspect thereof, the human subject has a SALT score of 20 or less after treatment.

[0026] In an eleventh aspect of any one of the first to sixth embodiments, or the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, or tenth aspect thereof, the CYP3A4 inhibitor is a strong CYP3A4 inhibitor.

[0027] In a twelfth aspect of any one of the first to sixth embodiments, or the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, or tenth aspects thereof, the CYP3A4 inhibitor is selected from boceprevir, cobicistat, danoprevir + ritonavir, elvitegravir + ritonavir, grapefruit juice, indinavir + ritonavir, itraconazole, ketoconazole, lopinavir + ritonavir, paritaprevir + ritonavir + (ombitasvir and / or dasabuvir), posaconazole, ritonavir, saquinavir + ritonavir, telaprevir, tipranavir + ritonavir, telithromycin, troleandomycin, voriconazole, clarithromycin, idelalisib, nefazodone, and nelfinavir.

[0028] In a thirteenth aspect of any one of the first through sixth embodiments, or the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, or twelfth aspects thereof, there is no need to interrupt administration of the CYP3A4 inhibitor.

[0029] In a seventh embodiment, the present invention relates to a method of treating a hair loss disorder in a human subject in need thereof, the human subject being co-administered with a strong CYP3A4 inhibitor, the method comprising administering to the subject a compound (I) represented by the following structural formula: [ka] or a pharma- ceutical acceptable salt thereof, wherein each position specifically designated as deuterium has at least 95% deuterium incorporation; Compound (I) The therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof, is not decreased compared to the therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof, that would be administered to a subject in the absence of concomitant administration of a strong CYP3A4 inhibitor.

[0030] In a first aspect of the seventh embodiment, the hair loss disorder is alopecia areata.

[0031] In the second aspect of the seventh embodiment, or in the first aspect thereof, Compound (I), or a pharma- ceutically acceptable salt thereof, is administered in an amount within the range of about 8 mg to about 32 mg per day.

[0032] In the third aspect of the seventh embodiment, or the first or second aspect thereof, Compound (I), or a pharma- ceutically acceptable salt thereof, is administered at about 16 mg / day, or about 24 mg / day.

[0033] In the fourth aspect of the seventh embodiment, or the first, second, or third aspects thereof, about 16 mg / day of Compound (I), or a pharma- ceutically acceptable salt thereof, is administered as about 8 mg twice a day, and about 24 mg / day of the compound, or a pharma- ceutically acceptable salt thereof, is administered as about 12 mg twice a day.

[0034] For any one of the first to sixth embodiments, in the fifth aspect, or the first or second aspects thereof, about 8 mg / day of Compound (I), or a pharma- ceutically acceptable salt thereof, is administered at about 8 mg once a day, or at 4 mg twice a day.

[0035] In the sixth aspect of any one of the first through sixth embodiments, or the first, second, third, fourth, or fifth aspect thereof, Compound (I), or a pharma- ceutically acceptable salt thereof, is administered orally.

[0036] In a seventh aspect of any one of the first through sixth embodiments, or the first, second, third, fourth, fifth, or sixth aspects thereof, Compound (I), or a pharma- ceutically acceptable salt thereof, is administered in a pharmaceutical formulation that is a tablet.

[0037] In an eighth aspect of any one of the first to sixth embodiments, or in the first, second, third, fourth, fifth, sixth, or seventh aspect thereof, Compound (I), or a pharma- ceutically acceptable salt thereof, is administered to a human subject for at least 24 weeks.

[0038] In a ninth aspect of any one of the first to sixth embodiments, or the first, second, third, fourth, fifth, sixth, seventh, or eighth aspect thereof, in compound (I), each position specifically designated as deuterium has at least 97% deuterium incorporation.

[0039] In a tenth aspect of any one of the first to sixth embodiments, or the first, second, third, fourth, fifth, sixth, seventh, eighth, or ninth aspect thereof, the human subject has a SALT score of 20 or less after treatment.

[0040] In an eleventh aspect of the seventh embodiment, or the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, or tenth aspects thereof, there is no need to discontinue administration of the CYP3A4 inhibitor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] definition Compound I

[0042] As referred to herein, compound I is (R)-3-(4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl)-3-(cyclopentyl-2,2,3,3,4,4,5,5-d8)propanenitrile. [ka]

[0043] Compound I, also referred to herein as CTP-543, is a potent selective inhibitor of Janus kinases JAK1 and JAK2.The compound is disclosed in International Patent Applications WO2013 / 188783A1, WO2017 / 192905A1, and WO2020 / 163653.CTP-543 is currently being studied in human clinical trials and has been shown to promote hair growth in patients suffering from alopecia areata.

[0044] Synthesis of compound (I), or a pharma- ceutically acceptable salt thereof (such as a phosphate salt), can be readily accomplished by the methods described in U.S. Pat. No. 9,249,149, WO 2017 / 192905A1 or WO 2020 / 163653, the teachings of which are incorporated herein by reference with appropriate amendments, if necessary. Additional methods for preparing ruxolitinib (i.e., the non-deuterated analog compound (I)) are disclosed in U.S. Pat. No. 9,000,161 and can be used to prepare compound (I) using an appropriate deuterated reagent.

[0045] Such methods may be carried out utilizing the corresponding deuterated, and optionally other isotopically-containing reagents and / or intermediates to synthesize the compounds detailed herein, or by invoking standard synthetic protocols known in the art for introducing isotopic atoms into a chemical structure.

[0046] As noted above, Compound I is referred to as the “free base.” In some embodiments, a pharma- ceutically acceptable salt of Compound (I) is used.

[0047] The pharma- ceutically acceptable salt of compound I includes acid addition salts formed with inorganic or organic acids. Suitable inorganic acids include hydrochloric acid, hydrobromic acid, sulfuric acid, and phosphoric acid. Suitable organic acids include paratoluenesulfonic acid, salicylic acid, tartaric acid, ascorbic acid, maleic acid, besylic acid, fumaric acid, gluconic acid, glucuronic acid, formic acid, glutamic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, lactic acid, oxalic acid, succinic acid, citric acid, benzoic acid, and acetic acid. In certain embodiments, the pharma- ceutically acceptable salt of compound (I) is selected from sulfate, phosphate, paratoluenesulfonate, and methanesulfonate (mesylate).

[0048] In certain embodiments, the pharma- ceutically acceptable salt of compound (I) is a phosphate salt.Conveniently, a phosphate salt of compound I (in a molar ratio of 1:1) is used.The phosphate salt of compound (I) is shown below. [ka]

[0049] The molecular weight of Compound I is 314.2 g / mol. The molecular weight of the 1:1 phosphate salt of Compound (I) is 412.2 g / mol.

[0050] In one embodiment, the ratio of compound I to the salt form of phosphate is about 1:1.

[0051] In one embodiment, any atom not designated as deuterium is present at its natural isotopic abundance in Compound (I) or a pharma- ceutically acceptable salt thereof.

[0052] The pharma- ceutically acceptable salt of Compound I may exist in hydrate, solvate or anhydrous form.In certain embodiments, the pharma- ceutically acceptable salt is anhydrous.In more particular embodiments, the phosphate salt is anhydrous.

[0053] Throughout this specification, unless otherwise specified, references to the amount of Compound I will be understood to refer to the amount of the parent compound on a free base basis, even if the compound is present as a salt of Compound I.

[0054] Purely by way of example, a reference to 12 mg of Compound I or a salt thereof will be understood to refer to 12 mg of the free base, or a salt of Compound I having 12 mg of the free base equivalent. In the context of the anhydrous monophosphate salt of Compound (I), approximately 15.7 mg of the salt delivers 12 mg of Compound (I) (free base equivalent).

[0055] Synthesis of Compound I, or a pharma- ceutically acceptable salt thereof (such as a phosphate salt), can be readily accomplished by the methods described in WO 2020 / 163653, the teachings of which are incorporated herein by reference.

[0056] CYP3A4 inhibitors

[0057] Cytochrome P450 (CYP) is a well-known superfamily of enzymes involved in the oxidative and reductive metabolic transformation of drugs used in clinical practice. In addition, CYP enzymes are commonly implicated in causing many clinically relevant drug-drug interactions. Among CYP enzymes, CYP3A4 is not only the most common CYP enzyme found in the liver, but also the enzyme that is used by more than 50% of marketed drugs for metabolism and elimination from the body. Furthermore, CYP3A4 activity can be induced (or accelerated) or inhibited (decreased), thereby altering the drug concentration present in the body and its pharmacokinetic profile. Inhibition of CYP3A4 can lead to accumulation of parent drug concentrations, potentially exposing patients to increased risk of side effects and toxicity.

[0058] According to US FDA guidance, strong, moderate, and weak inhibitors are drugs that increase the AUC of a sensitive indicator substrate of a given metabolic pathway by 5-fold or more, 2-fold to less than 5-fold, and 1.25-fold to less than 2-fold, respectively. The list reproduced below is provided by the FDA (https: / / www.fda.gov / drugs / drug-interactions-labeling / drug-development-and-drug-interactions-table-substrates-inhibitors-and-inducers#table3-2). The list provided by the FDA is not exhaustive. Thus, CYP3A4 inhibitors include, but are not limited to, the inhibitors listed below:

[0059] Strong inhibitors: boceprevir, cobicistat, danoprevir + ritonavir, elvitegravir + ritonavir, grapefruit juice, indinavir + ritonavir, itraconazole, ketoconazole, lopinavir + ritonavir, paritaprevir + ritonavir + (ombitasvir and / or dasabuvir), posaconazole, ritonavir, saquinavir + ritonavir, telaprevir, tipranavir + ritonavir, telithromycin, troleandomycin, voriconazole, clarithromycin, idelalisib, nefazodone, and nelfinavir.

[0060] Moderate inhibitors: aprepitant, ciprofloxacin, conivaptan, crizotinib, cyclosporine, diltiazem, dronedarone, erythromycin, fluconazole, fluvoxamine, imatinib, tofisopam, and verapamil.

[0061] Weak inhibitors: chlorzoxazone, cilostazol, cimetidine, clotrimazole, fosaprepitant, istradefylline, ivacaftor, lomitapide, ranitidine, ranolazine, and ticagrelor.

[0062] The term "treat" refers to reducing, inhibiting, attenuating, decreasing, arresting, or stabilizing the onset or progression of a disease (e.g., a disease or disorder detailed herein), reducing the severity of a disease, or ameliorating symptoms associated with a disease. For example, treating a hair loss disorder includes regrowing hair, preventing further hair loss, or reducing the rate of hair loss.

[0063] The term "JAK inhibition responsive state" refers to a disease or disorder in a mammalian (e.g., human) subject that can be treated by inhibiting the activity of JAK (JAK1 and / or JAK2) in the mammalian (e.g., human) subject.

[0064] In certain embodiments, a "JAK inhibition responsive state" is a condition that is a medical condition, including, but not limited to, conditions such as organ transplant rejection (e.g., allograft rejection and graft-versus-host disease); hair loss disorders such as alopecia (alopecia areata (AA), alopecia totalis, alopecia universalis); autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, juvenile arthritis, type I diabetes, lupus, psoriasis, inflammatory bowel disease, ulcerative colitis, Crohn's disease, myasthenia gravis, immunoglobulin nephropathy, autoimmune thyroid disorders; allergic conditions such as asthma, food allergies, atopic dermatitis and rhinitis; Epstein-Barr syndrome, and other conditions. viral diseases such as Barr virus (EBV), hepatitis B, hepatitis C, HIV, HTLV1, varicella-zoster virus (VZV) and human papillomavirus (HPV); skin disorders such as psoriasis (e.g., plaque psoriasis), atopic dermatitis, hidradenitis suppurativa, skin rash, dermatitis, skin sensitization (e.g., contact dermatitis or allergic contact dermatitis), and vitiligo; solid tumors (e.g., prostate cancer, renal cancer, liver cancer, pancreatic cancer, gastric cancer, breast cancer, lung cancer, cancer of the head and neck, thyroid cancer, glioblastoma, Kaposi's sarcoma, Castleman's disease, melanoma) hematological cancers (e.g., lymphoma, leukemia such as acute lymphoblastic leukemia, or multiple myeloma), and skin cancers such as cutaneous T-cell lymphoma (CTCL) and cutaneous B-cell lymphoma (examples of which include Sézary syndrome and mycosis fungoides); myeloproliferative disorders (MPDs) such as polycythemia vera (PV), essential thrombocythemia (ET), myelodysplasia with myelofibrosis (MMM), chronic myelomonocytic leukemia (CMML), hypereosinophilic syndrome (HES), and systemic mast cell disease (SMCD); ocular inflammatory diseases (e.g., iritis, staphylococcus aureus, and glaucoma); inflammation and inflammatory diseases such as inflammatory bowel disease, ocular diseases, chronic obstructive pulmonary disease, and the like; inflammatory diseases of the respiratory tract (e.g., upper respiratory tract including nose and sinuses such as rhinitis or sinusitis, or lower respiratory tract including bronchitis, chronic obstructive pulmonary disease, and the like); inflammatory myopathies such as myocarditis; systemic inflammatory response syndrome (SIRS) and septic shock; diseases or conditions associated with ischemia-reperfusion injury, or an inflammatory ischemic event such as stroke or cardiac arrest; anorexia; cachexia; fatigue resulting from or associated with cancer; restenosis; scleroderma; fibrosis;conditions associated with hypoxia or astrogliosis, such as diabetic retinopathy, cancer or neurodegeneration; gout; increased prostate size due to benign prostatic hyperplasia or benign prostatic hyperplasia; and diseases involving the immune system, including androgenetic alopecia and other hair loss disorders such as telogen effluvium;

[0065] In certain embodiments, a "JAK inhibition responsive state" is a condition that is a chronic condition, such as, but not limited to, organ transplant rejection (e.g., allograft rejection and graft-versus-host disease); hair loss disorders such as alopecia (alopecia areata (AA), alopecia totalis, alopecia universalis); autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, juvenile arthritis, type I diabetes, lupus, psoriasis, inflammatory bowel disease, ulcerative colitis, Crohn's disease, myasthenia gravis, immunoglobulin nephropathy, autoimmune thyroid disorders; allergic conditions such as asthma, food allergies, atopic dermatitis and rhinitis; Epstein-Barr syndrome, and the like; viral diseases such as EBV, hepatitis B, hepatitis C, HIV, HTLV1, varicella-zoster virus (VZV) and human papillomavirus (HPV); skin disorders such as psoriasis (e.g., plaque psoriasis), atopic dermatitis, hidradenitis suppurativa, skin rash, dermatitis, and skin sensitization (e.g., contact dermatitis or allergic contact dermatitis); solid tumors (e.g., prostate cancer, renal cancer, liver cancer, pancreatic cancer, gastric cancer, breast cancer, lung cancer, cancer of the head and neck, thyroid cancer, glioblastoma, Kaposi's sarcoma, Castleman's disease, melanoma), hematological cancers (e.g., lymphoma, leukemia such as acute lymphoblastic leukemia, or multiple myeloma), and skin cancers such as cutaneous T-cell lymphoma (CTCL) and cutaneous B-cell lymphoma (examples of which include Sézary syndrome and mycosis fungoides); myeloproliferative disorders (MPDs) such as polycythemia vera (PV), essential thrombocythemia (ET), myelodysplasia with myelofibrosis (MMM), chronic myelomonocytic leukemia (CMML), hypereosinophilic syndrome (HES), and systemic mast cell disease (SMCD); ocular inflammatory diseases (e.g., iritis, uveal tract infections, and inflammatory bowel disease); inflammation and inflammatory diseases such as inflammatory bowel disease, scleritis, conjunctivitis, or related disorders, inflammatory diseases of the respiratory tract (e.g., upper respiratory tract including nose and sinuses such as rhinitis or sinusitis, or lower respiratory tract including bronchitis, chronic obstructive pulmonary disease, and the like), inflammatory myopathies such as myocarditis; systemic inflammatory response syndrome (SIRS) and septic shock; diseases or conditions associated with ischemia-reperfusion injury, or an inflammatory ischemic event such as stroke or cardiac arrest; anorexia; cachexia; fatigue resulting from or associated with cancer; restenosis; scleroderma; fibrosis;conditions associated with hypoxia or astrogliosis, such as diabetic retinopathy, cancer or neurodegeneration; gout; increased prostate size due to benign prostatic hyperplasia or benign prostatic hyperplasia; and diseases involving the immune system, including androgenetic alopecia and other hair loss disorders such as telogen effluvium;

[0066] In certain embodiments, the condition is selected from a hair loss disorder, polycythemia vera (PV), myelofibrosis (MF), or acute graft-versus-host disease (aGVHD). In certain embodiments, the JAK inhibition responsive state is a hair loss disorder.

[0067] "Hair loss disorder" refers to any condition or disorder that causes hair loss in one or more areas of the body.Hair loss disorders include, but are not limited to, androgenetic alopecia, alopecia areata, telogen effluvium, alopecia totalis, and alopecia universalis.In certain embodiments, the hair loss disorder is alopecia areata.

[0068] Alopecia areata is an autoimmune disease that causes partial or complete loss of hair on the scalp and body, potentially affecting up to 650,000 Americans at any one time. The scalp is the most commonly affected area, but any hairy site may be affected alone or in combination with the scalp. Onset of the disease can occur throughout life, affecting both women and men. Alopecia areata can be associated with severe psychological consequences, including anxiety and depression. Currently, there are no drugs approved by the U.S. Food and Drug Administration (FDA) for the treatment of alopecia areata.

[0069] In certain embodiments, the condition is alopecia areata in a subject, such as a mammalian (e.g., human) patient in need thereof. In certain embodiments, the alopecia areata is moderate to severe alopecia areata (e.g., hair loss of at least 30% of the scalp, hair loss of at least 40% of the scalp, or hair loss of at least 50% of the scalp).

[0070] As used herein, the term "mammal" includes humans, and non-human mammals such as cats, dogs, sheep, cows, pigs, goats, non-human primates (including monkeys and hominins).

[0071] As used herein, the terms "concomitant" and "concomitantly" refer to the administration of at least two drugs to a subject, where the second drug is administered sequentially or simultaneously within a period of time so that the effect of the first administered drug is still sustained in the patient.For example, in some embodiments, the co-administration of the second drug (e.g., a CYP3A4 inhibitor) is performed one day before or one day after the administration of the first drug.Thus, when a subject is described as receiving co-administration of a CYP3A4 inhibitor, the subject may have already taken a CYP3A4 inhibitor, or the subject may be planning to take (will take) a CYP3A4 inhibitor.

[0072] The phrase "is not decreased compared to the therapeutically effective amount of compound (I) or its pharma- ceutically acceptable salt that would be administered to a subject in the absence of co-administration of a CYP3A4 inhibitor" means that the dose of compound (I) administered to a subject undergoing co-treatment with a CYP3A4 inhibitor is the same as the dose that would be administered to a subject in the absence of treatment with a CYP3A4 inhibitor.For example, the dose that would be administered to a subject in the absence of treatment with a CYP3A4 inhibitor can be the dose approved by the FDA or its corresponding foreign agency for the treatment of a specified disease or condition.

[0073] It is recognized that, depending on the origin of the chemicals used in synthesis, some variation in natural isotopic abundance occurs in the synthesized compound.Therefore, preparations of ruxolitinib inherently contain a small amount of deuterated isotope substitution.Despite this variation, the concentration of naturally abundant stable hydrogen and carbon isotopes is small and immaterial compared to the degree of stable isotope substitution of deuterated compounds of the present invention.See, for example, Wada, E et al., Seikagaku, 1994, 66:15; Gannes, LZ et al., Comp Biochem Physiol Mol Integr Physiol, 1998, 119:725.

[0074] In any compound described herein, such as compound I, any atom not specifically designated as a particular isotope is meant to represent any stable isotope of that atom. Unless otherwise stated, when a position is specifically designated as "H" or "hydrogen", it is understood that the position has hydrogen at its natural abundance isotopic composition. However, in certain embodiments described, when a position is specifically designated as "H" or "hydrogen", the position has at least 80%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% hydrogen. In some embodiments, as detailed, when a position is specifically designated as "H" or "hydrogen", the position incorporates ≦20% deuterium, ≦10% deuterium, ≦5% deuterium, ≦4% deuterium, ≦3% deuterium, ≦2% deuterium, or ≦1% deuterium. Also, unless otherwise noted, when a position is specifically designated as "D" or "deuterium," the position is understood to have deuterium at least 3340 times the natural abundance of deuterium, or 0.015% (i.e., at least 50.1% deuterium incorporation). The amount of deuterium incorporation at a designated position may be measured by analytical methods known to those of skill in the art, for example, by proton NMR.

[0075] As used herein, the term "isotopic enrichment factor" means the ratio between the isotopic abundance and the natural abundance of a specified isotope.

[0076] In other embodiments, deuterated compounds of the invention have an isotopic enrichment factor for each designated deuterium atom of at least 3500 (52.5% deuterium incorporation at each designated deuterium atom), at least 4000 (60% deuterium incorporation), at least 4500 (67.5% deuterium incorporation), at least 5000 (75% deuterium), at least 5500 (82.5% deuterium incorporation), at least 6000 (90% deuterium incorporation), at least 6333.3 (95% deuterium incorporation), at least 6466.7 (97% deuterium incorporation), at least 6600 (99% deuterium incorporation), or at least 6633.3 (99.5% deuterium incorporation).

[0077] In some embodiments, in the compounds of the invention, each designated deuterium position (or atom) has at least 52.5% deuterium incorporation. In some embodiments, in the compounds of the invention, each designated deuterium position has at least 60% deuterium incorporation. In some embodiments, in the compounds of the invention, each designated deuterium position has at least 67.5% deuterium incorporation. In some embodiments, in the compounds of the invention, each designated deuterium position has at least 75% deuterium incorporation. In some embodiments, in the compounds of the invention, each designated deuterium position has at least 80% deuterium incorporation. In some embodiments, in the compounds of the invention, each designated deuterium position has at least 85% deuterium incorporation. In some embodiments, in the compounds of the invention, each designated deuterium position has at least 90% deuterium incorporation. In some embodiments, in the compounds of the invention, each designated deuterium position has at least 95% deuterium incorporation. In some embodiments, in the compounds of the invention, each designated deuterium position has at least 97% deuterium incorporation. In some embodiments, in the compounds of the invention, each designated deuterium position has at least 98% deuterium incorporation. In some embodiments, in the compounds of the invention, each designated deuterium position has at least 99% deuterium incorporation. In some embodiments, in the compounds of the invention, each designated deuterium position has at least 99.5% deuterium incorporation.

[0078] The term "isotopyranoside" refers to a species whose chemical structure differs from any compound described herein only in its isotopic composition.

[0079] The term "compound" when referring to a deuterated compound of the invention, e.g., Compound I, refers to a collection of molecules having the same chemical structure, except that there may be isotopic variations among the constituent molecules of the molecule. Thus, it will be clear to one skilled in the art that a compound represented by a particular chemical structure containing a deuterium atom as shown also contains isotopic substitutions having hydrogen atoms at one or more of the designated deuterium positions in the structure. The relative amount of such isotopic substitutions in the compounds of the invention depends on several factors, including the isotopic purity of the deuterium reagent used to make the compound, and the efficiency of deuterium incorporation in the various synthetic steps used to prepare the compound. In certain embodiments, the relative amount of such isotopic substitutions as a whole is less than 49.9% of the compound. In other embodiments, the relative amount of such isotopic substitutions as a whole is less than 47.5%, less than 40%, less than 32.5%, less than 25%, less than 17.5%, less than 10%, less than 5%, less than 3%, less than 1%, or less than 0.5% of the compound.

[0080] The present invention also provides salts of compound I. The salts of the compounds of the present invention are formed between an acid group and a basic group of the compound, such as an amino acid functional group, or a base and an acid group of the compound, such as a carboxyl functional group. According to another embodiment, the compound is a pharma- ceutically acceptable acid addition salt, such as a phosphate salt.

[0081] As used herein, the term "pharmaceutically acceptable" refers to a composition that is, within the scope of sound medical judgment, suitable for use in contact with the tissues of humans and other mammals without undue toxicity, irritation, allergic reaction, and the like, commensurate with a reasonable benefit / risk ratio. A "pharmaceutically acceptable salt" means any non-toxic salt that is capable of providing, directly or indirectly, a compound of the invention upon administration to a recipient. A "pharmaceutically acceptable counterion" is an ionic portion of a salt that is not toxic when released from the salt upon administration to a recipient.

[0082] Acids commonly used to form pharma- ceutically acceptable salts include inorganic acids such as hydrogen disulfide, hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, and phosphoric acid, and organic acids such as paratoluenesulfonic acid, salicylic acid, tartaric acid, bitaric acid, ascorbic acid, maleic acid, besylic acid, fumaric acid, gluconic acid, glucuronic acid, formic acid, glutamic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, lactic acid, oxalic acid, para-bromophenylsulfonic acid, carbonic acid, succinic acid, citric acid, benzoic acid, and acetic acid, and related inorganic and organic acids. Accordingly, such pharma- ceutically acceptable salts include, but are not limited to, sulfate, pyrosulfate, bisulfate, sulfite, bisulfite, phosphate, monohydrogen phosphate, dihydrogen phosphate, metaphosphate, pyrophosphate, chloride, bromide, iodide, acetate, propionate, decanoate, caprylate, acrylic acid, formate, isobutyrate, caprate, heptanoate, propiolate, oxalate, malonate, succinate, suberate, sebate, fumarate, maleate, butyne-1,4-dioate, hexyne-1,6 ... The pharmaceutically acceptable acid addition salts include those formed with mineral acids such as hydrochloric acid and hydrobromic acid, and in particular those formed with organic acids such as maleic acid.

[0083] As used herein, the term "stable compound" refers to a compound that has sufficient stability to permit its manufacture and maintains the integrity of the compound for a sufficient period of time to be useful for the purposes detailed herein (e.g., formulation into a therapeutic product, an intermediate for use in the manufacture of a therapeutic compound, an isolatable or storable intermediate compound, treatment of a disease or condition responsive to a therapeutic agent).

[0084] "D" and "d" both refer to deuterium. "Stereoisomer" refers to both enantiomers and diastereomers. "Tert" and "t-" each refer to tertiary. "US" means the United States of America.

[0085] "Deuterium substituted" refers to the replacement of one or more hydrogen atoms with a corresponding number of deuterium atoms.

[0086] The term "treat" refers to reducing, inhibiting, attenuating, decreasing, arresting, or stabilizing the onset or progression of a disease (e.g., a disease or disorder detailed herein), reducing the severity of a disease, or ameliorating symptoms associated with a disease. For example, treating a hair loss disorder includes regrowing hair, preventing further hair loss, or reducing the rate of hair loss.

[0087] As used herein, the term "mammal" includes humans, and non-human mammals such as cats, dogs, sheep, cows, pigs, goats, non-human primates (including monkeys and hominins).

[0088] As used herein, a "therapeutically effective amount" is an amount sufficient to treat a target condition or disorder. If a drug is approved by the U.S. Food and Drug Administration (FDA), a "therapeutically effective amount" may be the dose approved by the FDA or its corresponding foreign agency for the treatment of a specified disease or condition.

[0089] Administration of Compound (I):

[0090] In certain embodiments, compound (I) is administered as a pharma- ceutically acceptable salt, such as a phosphate salt. Compound (I) can be administered in a dose range of about 4 mg to about 50 mg per day (or the equivalent weight based on a salt, such as a phosphate salt, of compound (I)), either as a single daily dose or in divided doses (e.g., twice daily).

[0091] One aspect of the method described herein for treating hair loss disorders includes administering to a subject (e.g., a mammalian subject receiving concomitant administration of a CYP3A4 inhibitor) a therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof (i.e., an equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt), once or twice daily, wherein the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is within the range of about 4 mg / day to about 50 mg / day, e.g., about 5 mg / day, about 10 mg / day, about 20 mg / day, about 30 mg / day, about 40 mg / day, or about 50 mg / day. In certain embodiments, the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is about 4 mg / day, 8 mg / day, 16 mg / day, 32 mg / day, or 48 mg / day. In certain embodiments, the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is 8 mg / day, 16 mg / day, 24 mg / day, or 32 mg / day. In certain embodiments, the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is 8 mg / day, 16 mg / day, 24 mg / day, or 32 mg / day. In certain embodiments, the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is 4 mg, 8 mg, 12 mg, or 16 mg, twice a day. In certain embodiments, the hair loss disorder is alopecia areata. In a preferred embodiment, the subject is a human. In certain embodiments, compound (I), or a pharma- ceutically acceptable salt thereof, such as a phosphate salt, is orally administered in any of the doses described herein. In another particular embodiment, compound (I), or a pharma- ceutically acceptable salt thereof, is orally administered in any of the doses described herein in a pharmaceutical formulation that is a tablet.

[0092] In an alternative aspect, the invention described herein provides a method for treating hair loss disorders, the method comprising topically administering a therapeutically effective amount of Compound (I), or a pharma- ceutically acceptable salt thereof (i.e., an equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt), to a subject (e.g., a mammalian subject co-administered with a CYP3A4 inhibitor). In certain embodiments, the compound is administered in a pharmaceutical composition formulated for topical administration, such as a cream, ointment, lotion, foam, or the like.

[0093] In another aspect, the present invention provides a method for inducing hair growth in a subject. The method comprises administering a therapeutically effective amount of Compound (I), or a pharma- ceutically acceptable salt thereof (i.e., an equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt), once or twice daily to a mammalian subject receiving concomitant administration of a CYP3A4 inhibitor, wherein the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is within the range of about 4 mg / day to about 50 mg / day, for example, about 5 mg / day, about 10 mg / day, about 20 mg / day, about 30 mg / day, about 40 mg / day, or about 50 mg / day. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is about 4 mg / day, 8 mg / day, 16 mg / day, 32 mg / day, or 48 mg / day. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 8 mg / day, 16 mg / day, 24 mg / day, or 32 mg / day.

[0094] In certain embodiments, the subject suffering from hair loss disorder suffers from alopecia areata. In a preferred embodiment, the subject is a human. In one embodiment, the subject is a human aged 6 years or older. Preferably, compound (I) or its pharmaceutically acceptable salt (such as phosphate) is orally administered at any of the doses described above. Preferably, compound (I) or its pharmaceutically acceptable salt is orally administered at any of the doses described above in a pharmaceutical formulation that is a tablet.

[0095] Another aspect of the present invention is a method for treating an autoimmune skin disorder that may be treated by a compound that modulates the activity of Janus-associated kinase 1 (JAK1) and / or Janus-associated kinase 2 (JAK2). The method comprises administering to a subject (e.g., a mammalian subject receiving a concomitant CYP3A4 inhibitor) a therapeutically effective amount of Compound (I), or a pharma- ceutically acceptable salt thereof (i.e., an equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt), once or twice daily, wherein the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is within the range of about 4 mg / day to about 50 mg / day, e.g., about 5 mg / day, about 10 mg / day, about 20 mg / day, about 30 mg / day, about 40 mg / day, or about 50 mg / day. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is about 4 mg / day, 8 mg / day, 16 mg / day, 32 mg / day, or 48 mg / day. In certain embodiments, the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is 8 mg / day, 16 mg / day, 24 mg / day, or 32 mg / day. In certain embodiments, the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is 8 mg / day, 16 mg / day, 24 mg / day, or 32 mg / day. In certain embodiments, the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is 4 mg, 8 mg, 12 mg, or 16 mg, twice a day. In certain embodiments, the autoimmune skin disorder is alopecia areata, vitiligo, atopic dermatitis (eczema), or psoriasis. In a preferred embodiment, the subject is a human. Preferably, compound (I), or a pharma- ceutically acceptable salt thereof, such as a phosphate salt, is orally administered in any of the doses described above. Preferably, compound (I), or a pharma- ceutical acceptable salt thereof, is orally administered in any of the doses described above in a pharmaceutical formulation that is a tablet.

[0096] Another aspect of the present invention is compound (I), or its pharma- ceutically acceptable salt (i.e., the equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt), for use in treating hair loss disorders that can be treated by compounds that modulate the activity of Janus kinase 1 (JAK1) and / or Janus kinase 2 (JAK2).The compound may be administered in the dosage regimen disclosed herein.In certain embodiments, the hair loss disorder is alopecia areata.

[0097] In one aspect, the present invention provides a method for treating hair loss disorders that can be treated by a compound that modulates (e.g., inhibits) the activity of JAK (e.g., JAK1 and / or JAK2). The method comprises administering a therapeutically effective amount of Compound (I), or a pharma- ceutically acceptable salt thereof (i.e., an equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt), to a mammalian subject once or twice daily, wherein the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is within the range of about 4 mg / day to about 50 mg / day (e.g., 4 mg / day to 50 mg / day), for example, about 5 mg / day (e.g., 5 mg / day), about 10 mg / day (e.g., 10 mg / day), about 20 mg / day (e.g., 20 mg / day), about 30 mg / day (e.g., 30 mg / day), about 40 mg / day (e.g., 40 mg / day), or about 50 mg / day (e.g., 50 mg / day).

[0098] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof (i.e., the equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt) administered in a method for treating a hair loss disorder is about 4 mg / day (e.g., 4 mg / day), about 8 mg / day (e.g., 8 mg / day), about 16 mg / day (e.g., 16 mg / day), about 32 mg / day (e.g., 32 mg / day), or about 48 mg / day (e.g., 48 mg / day).

[0099] In certain embodiments, the amount of compound (I) or its pharmaceutically acceptable salt administered in the method for treating hair loss disorder is about 8mg / day (e.g., 8mg / day), about 16mg / day (e.g., 16mg / day), about 24mg / day (e.g., 24mg / day) or about 32mg / day (e.g., 32mg / day).In certain embodiments, the amount of compound (I) or its pharmaceutically acceptable salt is about 8mg / day (e.g., 8mg / day), about 12mg / day (e.g., 12mg / day), about 16mg / day (e.g., 16mg / day), or about 24mg / day (e.g., 24mg / day).

[0100] In certain embodiments, the amount of Compound (I) or its pharmaceutically acceptable salt administered in the method for treating hair loss disorder is 10.6 mg / day of Compound (I) phosphate, for example, administered as a twice-daily dose of 5.3 mg. In certain embodiments, the amount of Compound (I) or its pharmaceutically acceptable salt is 21.1 mg / day of Compound (I) phosphate, for example, administered as a twice-daily dose of 10.5 mg. In certain embodiments, the amount of Compound (I) or its pharmaceutically acceptable salt is 31.6 mg / day of Compound (I) phosphate, for example, administered as a twice-daily dose of 15.8 mg. In certain embodiments, the amount of Compound (I) or its pharmaceutically acceptable salt is 42.2 mg / day of Compound (I) phosphate, for example, administered as a twice-daily dose of 21.1 mg.

[0101] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in the method for treating hair loss disorders is about 4 mg (e.g., 4 mg) twice a day. In certain embodiments, Compound (I) is administered as about 5.3 mg (e.g., 5.3 mg) of Compound (I) phosphate salt twice a day. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in the method for treating hair loss disorders is about 8 mg (e.g., 8 mg) twice a day. In certain embodiments, Compound (I) is administered as about 10.5 mg (e.g., 10.5 mg) of Compound (I) phosphate salt twice a day.

[0102] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in the method of treating hair loss disorders is about 12 mg (e.g., 12 mg) twice a day. In certain embodiments, Compound (I) is administered as about 15.8 mg (e.g., 15.8 mg) of the phosphate salt of Compound (I) twice a day. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in the method of treating hair loss disorders is about 16 mg (e.g., 16 mg) twice a day. In certain embodiments, Compound (I) is administered as about 21.1 mg (e.g., 21.1 mg) of the phosphate salt of Compound (I) twice a day. In certain embodiments, the hair loss disorder is alopecia areata. In a preferred embodiment, the subject is a human. In one embodiment, the subject is a human aged 6 years or older. Preferably, Compound (I), or a pharma- ceutically acceptable salt thereof (such as a phosphate salt) is orally administered at any of the doses described herein. Preferably, Compound (I), or a pharma- ceutically acceptable salt thereof, is administered orally in a pharmaceutical formulation that is a tablet, in any of the dosages described herein.

[0103] In another aspect, the present invention provides a method for inducing hair growth in a subject. The method comprises administering a therapeutically effective amount of Compound (I), or a pharma- ceutically acceptable salt thereof (i.e., an equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt), to a mammalian subject once or twice daily, wherein the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is within the range of about 4 mg / day to about 50 mg / day (e.g., 4 mg / day to 50 mg / day), for example, about 5 mg / day (e.g., 5 mg / day), about 10 mg / day (e.g., 10 mg / day), about 20 mg / day (e.g., 20 mg / day), about 30 mg / day (e.g., 30 mg / day), about 40 mg / day (e.g., 40 mg / day), or about 50 mg / day (e.g., 50 mg / day).

[0104] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in a method of inducing hair growth is about 4 mg / day (e.g., 4 mg / day), about 8 mg / day (e.g., 8 mg / day), about 16 mg / day (e.g., 16 mg / day), about 32 mg / day (e.g., 32 mg / day), or about 48 mg / day (e.g., 48 mg / day).

[0105] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in a method of inducing hair growth is about 8 mg / day (e.g., 8 mg / day), about 16 mg / day (e.g., 16 mg / day), about 24 mg / day (e.g., 24 mg / day), or about 32 mg / day (e.g., 32 mg / day). In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in a method of inducing hair growth is about 8 mg / day (e.g., 8 mg / day), about 12 mg / day (e.g., 12 mg / day), about 16 mg / day (e.g., 16 mg / day), or about 24 mg / day (e.g., 24 mg / day).

[0106] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in the method of inducing hair growth is 10.6 mg / day of Compound (I) phosphate, for example, administered as a twice-daily dose of 5.3 mg. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 21.1 mg / day of Compound (I) phosphate, for example, administered as a twice-daily dose of 10.5 mg. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 31.6 mg / day of Compound (I) phosphate, for example, administered as a twice-daily dose of 15.8 mg. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 42.2 mg / day of Compound (I) phosphate, for example, administered as a twice-daily dose of 21.1 mg.

[0107] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in a method of inducing hair growth is about 4 mg (e.g., 4 mg) twice daily. In certain embodiments, Compound (I) is administered as about 5.3 mg (e.g., 5.3 mg) of the phosphate salt of Compound (I) twice daily.

[0108] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in a method of inducing hair growth is about 8 mg (e.g., 8 mg) twice daily. In certain embodiments, Compound (I) is administered as about 10.5 mg (e.g., 10.5 mg) of the phosphate salt of Compound (I) twice daily.

[0109] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in a method of inducing hair growth is about 12 mg (e.g., 12 mg) twice daily. In certain embodiments, Compound (I) is administered as about 15.8 mg (e.g., 15.8 mg) of the phosphate salt of Compound (I) twice daily.

[0110] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in a method of inducing hair growth is about 16 mg (e.g., 16 mg) twice daily. In certain embodiments, Compound (I) is administered as about 21.1 mg (e.g., 21.1 mg) of the phosphate salt of Compound (I) twice daily.

[0111] In certain embodiments, the subject suffers from a hair loss disorder, and in further embodiments, the hair loss disorder is alopecia areata. In a preferred embodiment, the subject is a human. In one embodiment, the subject is a human aged 6 years or older. Preferably, compound (I), or its pharmaceutically acceptable salt (such as phosphate salt), is orally administered at any of the doses described above. Preferably, compound (I), or its pharmaceutically acceptable salt, is orally administered at any of the doses described above in a pharmaceutical formulation that is a tablet.

[0112] One aspect of the methods described herein for treating a JAK inhibition responsive state includes administering to a subject (e.g., a mammalian subject receiving concomitant administration of a CYP3A4 inhibitor) a therapeutically effective amount of Compound (I), or a pharma- ceutically acceptable salt thereof (i.e., an equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt), once or twice daily, wherein the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is within the range of about 4 mg / day to about 50 mg / day, e.g., about 5 mg / day, about 10 mg / day, about 20 mg / day, about 30 mg / day, about 40 mg / day, or about 50 mg / day. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is about 4 mg / day, 8 mg / day, 16 mg / day, 32 mg / day, or 48 mg / day. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 8 mg / day, 16 mg / day, 24 mg / day, or 32 mg / day. In certain embodiments, the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is 8 mg / day, 16 mg / day, 24 mg / day, or 32 mg / day. In certain embodiments, the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is 4 mg, 8 mg, 12 mg, or 16 mg, twice a day. In certain embodiments, the JAK inhibition responsive state is alopecia areata. In a preferred embodiment, the subject is a human. In certain embodiments, compound (I), or a pharma- ceutically acceptable salt thereof, such as a phosphate salt, is orally administered at any of the doses described herein. In another particular embodiment, compound (I), or a pharma- ceutically acceptable salt thereof, is orally administered at any of the doses described herein in a pharmaceutical formulation that is a tablet.

[0113] Another aspect of the invention is compound (I), or a pharma- ceutically acceptable salt thereof (i.e., the equivalent of a pharma- ceutically acceptable salt, such as a phosphate salt), for use in treating a JAK inhibition responsive state. The compound may be administered in the dosing regimens disclosed herein.

[0114] In one aspect, the present invention provides a method for treating a JAK inhibition responsive state. The method comprises administering a therapeutically effective amount of Compound (I), or a pharma- ceutically acceptable salt thereof (i.e., an equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt), to a mammalian subject once or twice daily, wherein the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is within the range of about 4 mg / day to about 50 mg / day (e.g., 4 mg / day to 50 mg / day), for example, about 5 mg / day (e.g., 5 mg / day), about 10 mg / day (e.g., 10 mg / day), about 20 mg / day (e.g., 20 mg / day), about 30 mg / day (e.g., 30 mg / day), about 40 mg / day (e.g., 40 mg / day), or about 50 mg / day (e.g., 50 mg / day).

[0115] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof (i.e., the equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt) administered in the method of treating a JAK inhibition responsive state is about 4 mg / day (e.g., 4 mg / day), about 8 mg / day (e.g., 8 mg / day), about 16 mg / day (e.g., 16 mg / day), about 32 mg / day (e.g., 32 mg / day), or about 48 mg / day (e.g., 48 mg / day).

[0116] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in the method of treating a JAK inhibition responsive state is about 8 mg / day (e.g., 8 mg / day), about 16 mg / day (e.g., 16 mg / day), about 24 mg / day (e.g., 24 mg / day), or about 32 mg / day (e.g., 32 mg / day). In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is about 8 mg / day (e.g., 8 mg / day), about 12 mg / day (e.g., 12 mg / day), about 16 mg / day (e.g., 16 mg / day), or about 24 mg / day (e.g., 24 mg / day).

[0117] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in the method for treating a JAK inhibition responsive state is 10.6 mg / day of Compound (I) phosphate, for example, administered as a 5.3 mg twice daily dose. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 21.1 mg / day of Compound (I) phosphate, for example, administered as a 10.5 mg twice daily dose. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 31.6 mg / day of Compound (I) phosphate, for example, administered as a 15.8 mg twice daily dose. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 42.2 mg / day of Compound (I) phosphate, for example, administered as a 21.1 mg twice daily dose.

[0118] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in the method of treating a JAK inhibition responsive state is about 4 mg (e.g., 4 mg) twice a day. In certain embodiments, Compound (I) is administered as about 5.3 mg (e.g., 5.3 mg) of Compound (I) phosphate salt twice a day. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in the method of treating hair loss disorder is about 8 mg (e.g., 8 mg) twice a day. In certain embodiments, Compound (I) is administered as about 10.5 mg (e.g., 10.5 mg) of Compound (I) phosphate salt twice a day.

[0119] In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in the method of treating a JAK inhibition responsive state is about 12 mg (e.g., 12 mg) twice a day. In certain embodiments, Compound (I) is administered as about 15.8 mg (e.g., 15.8 mg) of Compound (I) phosphate salt twice a day. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, administered in the method of treating a hair loss disorder is about 16 mg (e.g., 16 mg) twice a day. In certain embodiments, Compound (I) is administered as about 21.1 mg (e.g., 21.1 mg) of Compound (I) phosphate salt twice a day. In certain embodiments, the JAK inhibition responsive state is alopecia areata.

[0120] In a preferred embodiment, the subject is a human. In one embodiment, the subject is a human aged 6 years or older. Preferably, compound (I), or a pharmaceutically acceptable salt thereof (such as a phosphate salt), is orally administered in any of the doses described herein. Preferably, compound (I), or a pharmaceutically acceptable salt thereof, is orally administered in any of the doses described herein in a pharmaceutical formulation that is a tablet.

[0121] In one embodiment of any aspect, the compound is administered orally once daily. In another embodiment of any aspect, the compound is administered orally twice daily.

[0122] Effective doses will also vary, as recognized by those of skill in the art, depending on the disease being treated, the severity of the disease, the route of administration, the sex, age, and general health of the subject, the use of excipients, the use of other medications, and the possibility of co-use with other therapeutic treatments, such as the judgment of the treating physician.

[0123] Administration of Compound (I), or a pharma- ceutically acceptable salt thereof (such as a phosphate salt), can continue for as long as necessary to treat the hair loss disorder, for example, one week, two weeks, one month, two months, three months, four months, six months, one year, two years, five years, ten years, or more.

[0124] How to assess treatment effectiveness: The effectiveness of the treatment of hair loss disorders such as alopecia areata can be measured in various ways, some of which are known in the art.For example, the "severity of alopecia tool", known as SALT, is a validated assessment scale developed by the working committee of the National Alopecia Areata Foundation to assess the extent of hair loss.See, for example, Olsen EA, Hordinsky MK, Price VH, et al. Alopecia Areata Clinical Trial Assessment Guidelines-Part II. J Am Acad Dermatol 2004:51:440-447 (incorporated herein by reference).SALT score is calculated for a patient by measuring the percentage of hair loss in each of the four areas of the scalp and adding the sum to achieve a composite value.Hair regrowth is reflected by a decrease in SALT score.For example, completely no hair on the scalp has a SALT score of 100, while complete hair regrowth is a SALT score of 0. In certain embodiments, the treatment methods described herein can provide an improvement in the SALT score of at least 10 points after treatment (e.g., from a SALT score of 100 before treatment to a SALT score of 90 after treatment). In further embodiments, the treatment methods described herein can result in an improvement in the SALT score of at least 20 points, 30 points, 40 points, 50 points, 60 points, 70 points, 80 points, 90 points, or 100 points. In certain embodiments, the treatment methods described herein can provide at least a 20% improvement from baseline in the patient's SALT score, or at least a 30% improvement from baseline in the patient's SALT score, or at least a 40% improvement from baseline in the patient's SALT score, or at least a 50% improvement from baseline in the patient's SALT score, or at least a 60% improvement from baseline in the patient's SALT score, or at least a 70% improvement from baseline in the patient's SALT score.

[0125] In certain embodiments, the human subject has a SALT score of 20 or less after treatment (e.g., after at least four weeks of treatment, or after at least eight weeks of treatment, or after at least twelve weeks of treatment, or after at least sixteen weeks of treatment, or after at least twenty weeks of treatment, or after at least twenty-four weeks of treatment, or after at least twenty-eight weeks of treatment, or after at least thirty-two weeks of treatment, or after at least thirty-six weeks of treatment, or after at least forty weeks of treatment, or after at least forty-four weeks of treatment, or after at least forty-eight weeks of treatment, after at least fifty-two weeks or more of treatment).

[0126] In certain embodiments, treatment continues for a period of at least four weeks, at least eight weeks, or at least twelve weeks, or at least sixteen weeks, or at least twenty weeks, or at least twenty-four weeks, or at least twenty-eight weeks, or at least thirty-two weeks, or at least thirty-six weeks, or at least forty weeks, or at least forty-four weeks, or at least forty-eight weeks, or at least fifty-two weeks.

[0127] Combination therapy In certain embodiments, compound (I) or its pharmaceutically acceptable salt is administered in combination with a second therapeutic agent.Preferably, the second therapeutic agent is an agent useful for treating hair loss disorder or autoimmune conditions, such as an inhibitor of JAK1 or JAK2 or JAK3 and / or STAT1.Such inhibitors include ruxolitinib, tofacitinib, baricitinib, filgotinib, etc.Other orally administered second therapeutic agents include agents used for treating alopecia areata, including, for example, oral corticosteroids.

[0128] For pharmaceutical compositions containing a second therapeutic agent, the therapeutically effective amount of the second therapeutic agent is about 20%-100% of the dose normally used in a monotherapy regimen using only that agent. Preferably, the therapeutically effective amount is about 70%-100% of the normal monotherapy dose. The normal monotherapy doses of these second therapeutic agents are well known in the art. See, for example, Wells et al., eds., Pharmacotherapy Handbook, 2nd Edition, Appleton and Lange, Stamford, Conn. (2000); PDR Pharmacopoeia, Tarascon Pocket Pharmacopoeia 2000, Deluxe Edition, Tarascon Publishing, Loma Linda, Calif. (2000); FDA-approved labeling information for ruxolitinib and tofacitinib; and clinical trial information for baricitinib and filgotinib; each of which is incorporated herein by reference in its entirety.

[0129] Some of the above-mentioned second therapeutic agents are expected to act synergistically with the compounds of the present invention. When synergistic action occurs, the effective dose of the second therapeutic agent and / or compound (I), or its pharmaceutically acceptable salt, can be reduced from that required in monotherapy. This has the advantage of minimizing the toxic side effects of either the second therapeutic agent or compound (I), or its pharmaceutically acceptable salt, synergistic improvement in efficacy, improved ease of administration or use, and / or reduced overall cost of preparation or formulation of the compound.

[0130] In another embodiment, any of the above-mentioned treatment methods comprises the further step of co-administering one or more second therapeutic agents to a subject in need thereof. The selection of the second therapeutic agent may be made from any second therapeutic agent known to be useful in the treatment of hair loss disorders, such as alopecia areata. The selection of the second therapeutic agent also depends on the specific disease or condition to be treated. Examples of second therapeutic agents that can be employed in the method of the present invention are those described above for use in the combination composition comprising compound (I), or a pharma- ceutically acceptable salt thereof, and a second therapeutic agent. Additional therapeutic agents include, for example, agents used in the treatment of alopecia areata, including topical minoxidil, injectable corticosteroids, and anthralin cream or ointment.

[0131] As used herein, the term "co-administered" means that the second therapeutic agent can be administered together with compound (I), or a pharma- ceutically acceptable salt thereof, as part of a single dosage form (such as the composition of the present invention comprising the compound of the present invention and the second therapeutic agent described above) or as separate multiple dosage forms. Alternatively, the additional agent can be administered before, consecutively, or after the administration of compound (I), or a pharma- ceutically acceptable salt thereof. In such combination therapy treatment, both compound (I), or a pharma- ceutically acceptable salt thereof, and the second therapeutic agent are administered by conventional methods. The administration of the composition of the present invention comprising both compound (I), or a pharma- ceutically acceptable salt thereof, and the second therapeutic agent to a subject does not preclude the separate administration of the same therapeutic agent, any other second therapeutic agent, or compound (I), or a pharma- ceutically acceptable salt thereof, to the subject at another time during the course of treatment.

[0132] Therapeutically effective amounts of these second therapeutic agents are well known to those of skill in the art, and guidance for administration can be found in the patents and published patent applications referenced herein, as well as in Wells et al., eds., Pharmacotherapy Handbook, 2nd Edition, Appleton and Lange, Stamford, Conn. (2000), PDR Pharmacopoeia, Tarascon Pocket Pharmacopoeia 2000, Deluxe Edition, Tarascon Publishing, Loma Linda, Calif. (2000), and other medical literature. However, determining optimal effective amount ranges for the second therapeutic agents is well within the purview of one of ordinary skill in the art.

[0133] In one embodiment of the present invention, when a second therapeutic agent is administered to a subject, the therapeutically effective amount of compound (I), or a pharma- ceutically acceptable salt thereof, is less than its therapeutically effective amount when the second therapeutic agent is not administered. In another embodiment, the therapeutically effective amount of the second therapeutic agent is less than its therapeutically effective amount when the compound (I), or a pharma- ceutically acceptable salt thereof, is not administered. In this way, undesirable side effects associated with high doses of either agent can be minimized. Other potential advantages (including, but not limited to, improved dosing regimens and / or reduced drug costs) will be apparent to those skilled in the art.

[0134] In yet another aspect, the present invention provides the use of compound (I), or a pharma- ceutically acceptable salt thereof (i.e., an equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt), either alone or in combination with one or more of the above-mentioned second therapeutic agents in the manufacture of a medicament, in a single composition or in separate dosage forms, for the treatment or prophylaxis in a subject of the above-mentioned diseases, disorders or conditions. Another aspect of the present invention is compound (I), or a pharma- ceutically acceptable salt thereof, for use in the treatment or prophylaxis in a subject of the diseases, disorders or conditions detailed herein.

[0135] Pharmaceutical Compositions A pharmaceutical composition comprising about 4 mg to about 50 mg (e.g., about 5 mg, about 10 mg, about 20 mg, about 30 mg, about 40 mg or about 50 mg) of Compound (I), or an equivalent amount of a pharma- ceutically acceptable salt thereof, together with a pharma- ceutically acceptable carrier or diluent, may be used in the methods of treating hair loss described herein. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is about 4 mg, 8 mg, 16 mg, 24 mg, 32 mg, or 48 mg. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 4 mg, 8 mg, 12 mg, or 16 mg. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 5.3 mg of Compound (I) phosphate. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 10.5 or 10.6 mg of Compound (I) phosphate. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 15.8 mg of Compound (I) phosphate. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 21.1 mg of Compound (I) phosphate. In certain embodiments, the pharmaceutical composition is a tablet.

[0136] Another aspect of the present invention is the use of a unit dosage form comprising about 4 mg to about 50 mg (e.g., about 5 mg, about 10 mg, about 20 mg, about 30 mg, about 40 mg or about 50 mg) of compound (I), or an equivalent amount of a pharma- ceutically acceptable salt thereof, together with a pharma- ceutically acceptable carrier or diluent, in the method of treating hair loss described herein. In certain embodiments, the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is about 4 mg, 8 mg, 16 mg, 24 mg, 32 mg, or 48 mg. In certain embodiments, the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is 4 mg, 8 mg, 12 mg, or 16 mg. In certain embodiments, the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is 5.3 mg of compound (I) phosphate. In certain embodiments, the amount of compound (I), or a pharma- ceutically acceptable salt thereof, is 10.5 or 10.6 mg of compound (I) phosphate. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 15.8 mg of Compound (I) phosphate. In certain embodiments, the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is 21.1 mg of Compound (I) phosphate. In certain embodiments, the unit dosage form is a tablet.

[0137] A pharmaceutical composition comprising a therapeutically effective amount of Compound (I), or a pharma- ceutically acceptable salt thereof (i.e., the equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt), and a pharma- ceutically acceptable carrier can be used in the method of treating hair loss described herein. The carrier is "acceptable" in the sense of being compatible with the other ingredients of the formulation, and, in the case of a pharma- ceutically acceptable carrier, not harmful to the recipient thereof in the amounts used in the medicament. In certain embodiments, the pharmaceutical composition is provided as a unit dosage form.

[0138] The present invention provides a pharmaceutical composition comprising a pharma- ceutical product comprising a pharma- ceutical product and 4 to 50 mg of a compound represented by the following structural formula: [ka] or a pharma- ceutical acceptable salt thereof (i.e., an equivalent amount of a pharma- ceutical acceptable salt such as a phosphate salt), are provided for use in the methods described herein. Compound (I)

[0139] Pharmaceutically acceptable carriers, adjuvants and vehicles that may be used in the pharmaceutical compositions of the present invention include, but are not limited to, ion exchangers, alumina, aluminum stearate, lecithin, serum proteins such as human serum albumin, buffer substances such as phosphoric acid, glycine, sorbic acid, potassium sorbate, partial glyceride mixtures of saturated vegetable fatty acids, water, salts or electrolytes such as protamine sulfate, disodium hydrogen phosphate, potassium hydrogen phosphate, sodium chloride, zinc salts, colloidal silica, magnesium trisilicate, polyvinylpyrrolidone, cellulosic substances, polyethylene glycol, sodium carboxymethylcellulose, polyacrylates, waxes, polyethylene-polyoxypropylene-block polymers, polyethylene glycol and wool fat.

[0140] If necessary, the solubility and bioavailability of the compounds of the present invention in pharmaceutical compositions can be enhanced by methods well known in the art. One method includes the use of lipid excipients in the formulation. See "Oral Lipid-Based Formulations:Enhancing the Bioavailability of Poorly Water-Soluble Drugs(Drugs and the Pharmaceutical Sciences)" edited by David J.Hauss, Informa Healthcare, 2007; and "Role of Lipid Excipients in Modifying Oral and Parenteral Drug Delivery:Basic Principles and Biological Examples" edited by Kishor M.Wasan, Wiley-Interscience, 2006.

[0141] Another known method of enhancing bioavailability is the use of amorphous forms of the compounds of the invention, optionally formulated with poloxamers such as LUTROL™ and PLURONIC™ (BASF Corporation), or block copolymers of ethylene oxide and propylene oxide. See U.S. Patent No. 7,014,866, and U.S. Patent Publications 20060094744 and 20060079502.

[0142] The pharmaceutical composition of the present invention includes those suitable for oral administration.Other formulations can be conveniently presented in unit dosage form, such as tablets, sustained release capsules, granules, and liposomes, and can be prepared by any method well known in the art of pharmacy.See, for example, Remington: The Science and Practice of Pharmacy, Lippincott Williams&Wilkins, Baltimore, MD (20th edition, 2000).

[0143] Such preparative techniques include the step of bringing into association the molecule with the ingredient to be administered, such as the carrier which constitutes one or more accessory ingredients. In general, the compositions are prepared by uniformly and intimately bringing into association the active ingredients with liquid carriers, liposomes, or finely divided solid carriers, or both, and then, if necessary, shaping the product.

[0144] In certain embodiments, the compound is administered orally.The composition of the present invention suitable for oral administration can be presented as a discrete unit such as capsule, sachet, or tablet, each containing a predetermined amount of active ingredient, powder or granule, solution or suspension in aqueous or non-aqueous liquid, oil-in-water liquid emulsion, water-in-oil liquid emulsion, liposome-filled, or as a bolus.Soft gelatin capsules can be useful for containing such suspension, which can advantageously increase the absorption rate of the compound.In certain embodiments, the compound is administered orally as tablet.

[0145] For oral tablets, commonly used carriers include lactose and corn starch. Lubricants such as magnesium stearate are also typically added. For oral administration in capsule form, useful diluents include lactose and dried corn starch. When aqueous suspension is administered orally, active ingredient is combined with emulsifying and suspending agents. If desired, certain sweetening and / or flavoring and / or coloring agents may be added. In another embodiment, the composition is in the form of a tablet. In a particular embodiment, an exemplary formulation for tablets is disclosed in U.S. Pat. No. 8,754,224, the teachings of which are incorporated herein by reference.

[0146] In certain embodiments, the tablet formulation contains about 4mg to about 50mg of Compound (I), or its pharma- ceutically acceptable salt (such as phosphate salt), and the inactive ingredients of colloidal silicon dioxide, magnesium stearate, microcrystalline cellulose, and povidone in equivalent amounts.Wet granulation followed by compression provides a tablet containing Compound (I), or its pharma- ceutically acceptable salt.For example, to prepare a 200mg tablet containing the equivalent of 16mg of Compound (I), 10.6wt% of Compound (I) phosphate salt and 64.44wt% of Avicel PH-101 microcrystalline cellulose are mixed in a high shear granulator, and 8.5%w / w of Kollidon 30 solution (Kollidon 30, containing polyvinylpyrrolidone (povidone)) is added; 5wt% (based on the total weight of the formulation) is added while mixing to form granules. The granules are tray dried in an oven at 60±10° C. and milled using a Quadro Comil U5 mill. The granules retained on the comil screen are passed through a #20 mesh sieve using a stainless steel spatula. The resulting milled granules are mixed with Avicel PH-200 microcrystalline cellulose (18.5% by weight), Aerosil 200 colloidal silicon dioxide (0.5% by weight) and Hyqual magnesium stearate (1% by weight) in a Turbula mixer to form the final blend. The final blend is compressed into 200 mg tablets using a Riva Piccola rotary press equipped with 0.451″×0.229″ D-type modified capsule shape tooling. Each tablet contains 21.1 mg of Compound (I) (equivalent to 16 mg of Compound (I) free base).

[0147] In certain embodiments, the tablet contains about 10.5 mg or about 10.6 mg of the phosphate salt of Compound (I) (equivalent to 8 mg of Compound (I) free base).

[0148] In certain embodiments, the tablet comprises the following ingredients: [Table 1]

[0149] In another particular embodiment, the tablet comprises the following ingredients: [Table 2]

[0150] In an alternative specific embodiment, the tablet comprises the following ingredients: [Table 3]

[0151] In yet another particular embodiment, the tablet comprises the following ingredients: [Table 4]

[0152] In another embodiment, the pharmaceutical composition of the present invention further comprises a second therapeutic agent, which may be selected from any compound or therapeutic agent known or exhibiting advantageous properties when administered together with a compound having the same mechanism of action as ruxolitinib.

[0153] Preferably, the second therapeutic agent is an agent useful for treating hair loss disorders or autoimmune conditions, including inhibitors of JAK1, JAK2 or JAK3 and / or STAT1. Such inhibitors include ruxolitinib, tofacitinib, baricitinib, filgotinib, etc. Other second therapeutic agents include oral corticosteroids.

[0154] In another embodiment, the present invention provides separate dosage forms of Compound (I), or a pharma- ceutically acceptable salt thereof, and any one or more of the second therapeutic agents described above, wherein Compound (I), or a pharma- ceutically acceptable salt thereof, and the second therapeutic agent are associated with each other. As used herein, the term "associated with each other" means that the separate dosage forms are packaged together or sold together and are attached to each other in such a way that it is readily apparent that the separate dosage forms are intended to be administered (within less than 24 hours of each other, either sequentially or simultaneously).

[0155] In the pharmaceutical composition of the present invention, compound (I) or its pharma- ceutical acceptable salt is present in a therapeutically effective amount.As used herein, the term "therapeutically effective amount" refers to an amount that is sufficient to treat the target disorder when administered in a suitable dosage regimen.

[0156] The interrelationship of animal and human doses (based on milligrams per square meter of body surface) is described in Freireich et al., Cancer Chemother. Rep, 1966, 50:219. Body surface area can be approximately determined from the subject's height and weight. See, e.g., Scientific Tables, Geigy Pharmaceuticals, Ardsley, NY, 1970, 537.

[0157] In one embodiment, a therapeutically effective amount of Compound (I) (either as the free base or as an equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt) may be in the range of about 4 mg to 50 mg per day (e.g., 4 mg to 50 mg per day), e.g., about 5 mg / day (e.g., 5 mg / day), about 10 mg / day (e.g., 10 mg / day), about 20 mg / day (e.g., 20 mg / day), about 30 mg / day (e.g., 30 mg / day), about 40 mg / day (e.g., 40 mg / day), or about 50 mg / day (e.g., 50 mg / day). In certain embodiments, the amount is about 4 mg / day (e.g., 4 mg / day), about 8 mg / day (e.g., 8 mg / day), about 16 mg / day (e.g., 16 mg / day), about 24 mg / day (e.g., 24 mg / day), about 32 mg / day (e.g., 32 mg / day), or about 48 mg / day (e.g., 48 mg / day). In certain embodiments, about 4 mg / day (e.g., 4 mg / day), about 8 mg / day (e.g., 8 mg / day), about 16 mg / day (e.g., 16 mg / day), about 24 mg / day (e.g., 24 mg / day), about 32 mg / day (e.g., 32 mg / day), or about 48 mg / day (e.g., 48 mg / day) is administered once a day. In a particular example, the 16 mg / day dose is administered as two 8 mg tablets of Compound (I) (as the free base or as an equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt) administered together (i.e., as a single dose). In another particular example, the 16 mg / day dose is administered as one 16 mg tablet of Compound (I) (as the free base or as an equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt). In another embodiment, the 4 mg / day, 8 mg / day, 16 mg / day, 24 mg / day, 32 mg / day, or 48 mg / day dose is administered twice daily in divided doses (e.g., the 48 mg / day dose is administered twice daily as 24 mg / day). In another embodiment, the 8 mg / day, 16 mg / day, 24 mg / day, or 32 mg / day doses are administered twice daily in split doses (e.g., the 32 mg / day dose is administered as 16 mg of Compound (I) (either as the free base or as the equivalent amount of a pharma- ceutically acceptable salt, such as a phosphate salt), i.e., administered twice daily in separate doses.In one particular embodiment, the 16 mg / day dose is administered twice a day, i.e., in separate doses, of 8 mg of Compound (I) (either as free base or as an equivalent amount of a pharma- ceutically acceptable salt, such as phosphate). References to the amount of Compound (I), or a pharma- ceutically acceptable salt thereof, include the amount of a pharma- ceutically acceptable salt of Compound (I) (such as phosphate), which is equivalent to a given amount of Compound (I) as free base (e.g., 10.5 mg of Compound (I) phosphate is equivalent to 8 mg of Compound (I) free base).

[0158] In certain embodiments, the therapeutically effective amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is about 4 mg (e.g., 4 mg) twice a day. In certain embodiments, the therapeutically effective amount of Compound (I) is administered as about 5.3 mg (e.g., 5.3 mg) of the phosphate salt of Compound (I) twice a day. In certain embodiments, the therapeutically effective amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is about 8 mg (e.g., 8 mg) twice a day. In certain embodiments, Compound (I) is administered as about 10.5 mg (e.g., 10.5 mg) of the phosphate salt of Compound (I) twice a day.

[0159] In certain embodiments, the therapeutically effective amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is about 12 mg (e.g., 12 mg) twice daily. In certain embodiments, the therapeutically effective amount of Compound (I) is about 15.8 mg (e.g., 15.8 mg) of a phosphate salt of Compound (I) twice daily. In certain embodiments, the therapeutically effective amount of Compound (I), or a pharma- ceutically acceptable salt thereof, is about 16 mg (e.g., 16 mg) twice daily. In certain embodiments, the therapeutically effective amount of Compound (I) is about 21.1 mg (e.g., 21.1 mg) of a phosphate salt of Compound (I) twice daily. EXAMPLES

[0160] Example 1: Drug-drug interaction study of CTP-543 (Compound (I)) and itraconazole (a strong CYP3A4 inhibitor) A drug interaction study was conducted in which healthy volunteers were administered 12 mg of Compound (I) (approximately 15.8 mg as the phosphate salt) on day 1, 200 mg of itraconazole on days 4-6, 12 mg of Compound (I) (approximately 15.8 mg as the phosphate salt) and 200 mg of itraconazole on day 7, and 200 mg of itraconazole on day 8.

[0161] Statistical comparisons of the plasma concentration data are shown in the table below. [Table 5]

[0162] Pharmacokinetic data show: (1) the C max (2) the AUC of compound (I) increases by only about 13% as a result of administering compound (I) with itraconazole, and (3) the half-life of compound (I) changes by 4.18 hours to 4.62 hours as a result of administering compound (I) with itraconazole. These changes in the pharmacokinetic parameters of compound (I) in the presence of itraconazole (a strong CYP3A4 inhibitor) are unexpectedly much less than those reported for ruxolitinib in the presence of ketoconazole, another strong CYP3A4 inhibitor. Specifically, the prescription label for ruxolitinib indicates that the C of ruxolitinib increases by only about 13% as a result of administering compound (I) with itraconazole, and (4) the half-life of compound (I) changes by 4.18 hours to 4.62 hours as a result of administering compound (I) with itraconazole. max reported that the ER increased by 33%, the AUC increased by 91%, and the half-life increased from 3.7 to 6.0 hours.

[0163] Although the above study used the CYP3A4 inhibitor itraconazole, and the study reported in the prescription label for ruxolitinib used the CYP3A4 inhibitor ketoconazole, itraconazole has been reported to have a significantly lower inhibition constant (Ki) than ketoconazole, suggesting that itraconazole is at least as potent a CYP3A4 inhibitor as ketoconazole. Furthermore, both ketoconazole and itraconazole are drugs classified by the FDA as strong CYP3A4 inhibitors and may be used as index drugs in drug-drug interaction studies. Regarding dosing, both inhibitors were administered at standard doses following FDA guidance.

[0164] Because the changes in the pharmacokinetic parameters of CTP543 in the presence of a strong CYP3A4 inhibitor are relatively modest and similar in magnitude to the changes in pharmacokinetic parameters reported for ruxolitinib in the presence of a moderate CYP3A4 inhibitor that do not require dose modification, the FDA is not expected to require a warning regarding coadministration of Compound (I) with a strong CYP3A4 inhibitor. Given that the prescribing information for ruxolitinib contains a warning regarding coadministration with a strong CYP3A4 inhibitor, this represents an unexpected advantage of Compound (I) over ruxolitinib, especially for a certain subset of patients taking a CYP3A4 inhibitor. Patients are often prescribed strong CYP3A4 inhibitors, such as those listed in the ruxolitinib prescribing information or the FDA table of inhibitors of drug-drug interactions. A drug that does not require dose adjustment or interruption when coadministered with a strong CYP3A4 inhibitor is a clinical advantage.

[0165] Without further description, it is believed that one skilled in the art can use the above description and illustrative examples to make and utilize the compounds of the present invention and to practice the claimed methods. It should be understood that the above discussion and examples merely provide detailed descriptions of certain preferred embodiments. It will be apparent to those skilled in the art that various modifications and equivalents can be made without departing from the spirit and scope of the present invention.

Claims

1. 1. Use of compound (I) or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for a method of treating a hair loss disorder in a human subject in need thereof, said method comprising orally administering to the human subject about 4 mg to about 50 mg of compound (I) or a pharmaceutically acceptable salt thereof, wherein compound (I) is represented by the following structural formula: 【Chemical 1】 wherein each position specifically designated as deuterium has at least 95% deuterium incorporation. In the method, (i) about 0.1 mg to about 200 mg of a CYP3A4 inhibitor are co-administered to a human subject; (ii) said co-administration of a CYP3A4 inhibitor does not require adjustment of the dose of compound (I) or a pharmaceutically acceptable salt thereof; The use, wherein the hair loss disorder is alopecia areata, alopecia totalis, or alopecia universalis.

2. 2. The use according to claim 1, wherein the hair loss disorder is alopecia areata.

3. 2. The use of claim 1, wherein in the method, compound (I) or a pharmaceutically acceptable salt thereof is administered at about 16 mg / day, or about 24 mg / day, wherein the about 16 mg / day of compound (I) or a pharmaceutically acceptable salt thereof is administered as about 8 mg twice a day, and the about 24 mg / day of compound (I) or a pharmaceutically acceptable salt thereof is administered as about 12 mg twice a day.

4. The use according to claim 1, wherein in the method, compound (I) or a pharmaceutically acceptable salt thereof is administered in a pharmaceutical formulation which is a tablet.

5. 2. The use according to claim 1, wherein the human subject has a SALT score of 20 or less after treatment.

6. The use according to claim 1, wherein the CYP3A4 inhibitor is a strong CYP3A4 inhibitor.

7. The use according to claim 1, wherein the method does not require discontinuation of administration of the CYP3A4 inhibitor.

8. 1. Use of compound (I) or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for a method of treating a hair loss disorder in a human subject in need thereof, said method comprising orally administering to the human subject about 4 mg to about 50 mg of compound (I) or a pharmaceutically acceptable salt thereof, wherein compound (I) is represented by the following structural formula: 【Chemistry 2】 wherein each position specifically designated as deuterium has at least 95% deuterium incorporation. (i) the subject is concomitantly receiving about 0.1 mg to about 200 mg of a CYP3A4 inhibitor; (ii) The use, wherein the amount of compound (I) or a pharmaceutically acceptable salt thereof is not reduced compared to the amount of compound (I) or a pharmaceutically acceptable salt thereof administered to the subject in the absence of concomitant administration of a CYP3A4 inhibitor, and the hair loss disorder is alopecia areata, alopecia totalis, or alopecia universalis.

9. 9. The use according to claim 8, wherein the hair loss disorder is alopecia areata.

10. 9. The use of claim 8, wherein in the method, compound (I) or a pharmaceutically acceptable salt thereof is administered at about 16 mg / day, or about 24 mg / day, wherein the about 16 mg / day of compound (I) or a pharmaceutically acceptable salt thereof is administered as about 8 mg twice a day, and the about 24 mg / day of compound (I) or a pharmaceutically acceptable salt thereof is administered as about 12 mg twice a day.

11. 9. The use according to claim 8, wherein compound (I) or a pharmaceutically acceptable salt thereof is administered in a pharmaceutical formulation which is a tablet.

12. 9. The use according to claim 8, wherein the human subject has a SALT score of 20 or less after treatment.

13. The use according to claim 8, wherein the CYP3A4 inhibitor is a strong CYP3A4 inhibitor.

14. The use according to claim 8, wherein the method does not require discontinuation of administration of the CYP3A4 inhibitor.

15. 1. Use of compound (I) or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for a method of treating a hair loss disorder in a human subject in need thereof, said method comprising orally administering to the human subject about 4 mg to about 50 mg of compound (I) or a pharmaceutically acceptable salt thereof, wherein compound (I) is represented by the following structural formula: 【Chemistry 3】 wherein each position specifically designated as deuterium has at least 95% deuterium incorporation. (i) the subject is determined to be concomitantly receiving about 0.1 mg to about 200 mg of a CYP3A4 inhibitor; (ii) The use, wherein the amount of compound (I) or a pharmaceutically acceptable salt thereof is not reduced compared to the amount of compound (I) or a pharmaceutically acceptable salt thereof administered to the subject in the absence of concomitant administration of a CYP3A4 inhibitor, and the hair loss disorder is alopecia areata, alopecia totalis, or alopecia universalis.

16. 16. The use according to claim 15, wherein the hair loss disorder is alopecia areata.

17. 16. The use of claim 15, wherein in the method, compound (I) or a pharmaceutically acceptable salt thereof is administered at about 16 mg / day, or about 24 mg / day, wherein the about 16 mg / day of compound (I) or a pharmaceutically acceptable salt thereof is administered as about 8 mg twice a day, and the about 24 mg / day of compound (I) or a pharmaceutically acceptable salt thereof is administered as about 12 mg twice a day.

18. 16. The use according to claim 15, wherein compound (I) or a pharmaceutically acceptable salt thereof is administered in a pharmaceutical formulation which is a tablet.

19. 16. The use according to claim 15, wherein the human subject has a SALT score of 20 or less after treatment.

20. 16. The use according to claim 15, wherein the CYP3A4 inhibitor is a strong CYP3A4 inhibitor.

21. The use according to claim 15, wherein the method does not require discontinuation of administration of the CYP3A4 inhibitor.

22. 1. Use of compound (I) or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for a method of treating a hair loss disorder in a human subject in need thereof, said method comprising: (iii) determining whether the human subject is receiving a concomitant CYP3A4 inhibitor; and (iv) orally administering to a human subject about 4 mg to about 50 mg of compound (I) or a pharmaceutically acceptable salt thereof, when the subject is concurrently receiving about 0.1 mg to about 200 mg of a CYP3A4 inhibitor, wherein compound (I) is represented by the following structural formula: 【Chemistry 4】 wherein each position specifically designated as deuterium has at least 95% deuterium incorporation. The use, wherein the amount of compound (I) or a pharmaceutically acceptable salt thereof is not reduced compared to the amount of compound (I) or a pharmaceutically acceptable salt thereof administered to the subject in the absence of concomitant administration of a CYP3A4 inhibitor, and the hair loss disorder is alopecia areata, alopecia totalis, or alopecia universalis.

23. 23. The use according to claim 22, wherein the hair loss disorder is alopecia areata.

24. 23. The use of claim 22, wherein in the method, compound (I) or a pharmaceutically acceptable salt thereof is administered at about 16 mg / day, or about 24 mg / day, wherein the about 16 mg / day of compound (I) or a pharmaceutically acceptable salt thereof is administered as about 8 mg twice a day, and the about 24 mg / day of compound (I) or a pharmaceutically acceptable salt thereof is administered as about 12 mg twice a day.

25. 23. The use according to claim 22, wherein compound (I) or a pharmaceutically acceptable salt thereof is administered in a pharmaceutical formulation which is a tablet.

26. 23. The use of claim 22, wherein the human subject has a SALT score of 20 or less after treatment.

27. 23. The use according to claim 22, wherein the CYP3A4 inhibitor is a strong CYP3A4 inhibitor.

28. 23. The use according to claim 22, wherein the method does not require discontinuation of administration of the CYP3A4 inhibitor.

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