Cross-Reference to Related Applications

This application claims the benefit of priority from U.S. Provisional Application No. 63/160,412, filed on March 12, 2021 and from U.S. Provisional Application No. 63/185,464, filed on May 7, 2021. The foregoing applications are incorporated herein by reference.

Field

Embodiments disclosed herein are directed to methods and uses to prevent or treat polycythemias with glycine transporter inhibitors, such as, but not limited to, GlyT 1 inhibitors, or pharmaceutically acceptable salts, solvates, prodrugs thereof, or pharmaceutical compositions thereof.

Background

Polycythemia is a disease characterized by an increase in a patient’s red blood cell count, hemoglobin, and total red blood cell volume, typically accompanied by an increase in total blood volume. Polycythemia can be distinguished from relative erythrocytosis secondary to fluid loss or decreased intake, because polycythemia results in increased total blood volume, and relative erythrocytosis does not. Two basic categories of polycythemia are typically recognized: primary polycythemias, which are due to factors intrinsic to red cell precursors and include the diagnoses of primary familial and congenital polycythemia (PFCP) and polycythemia vera (PV), and secondary polycythemias, which are caused by factors extrinsic to red cell precursors.

There is a high, unmet need for effective therapies for treating polycythemia. Accordingly, it is an object of the present disclosure to provide methods for treating, preventing, or reducing the progression rate and/or severity of polycythemia. The methods and use of glycine transporter inhibitors, such as, but not limited to, GlyT 1 inhibitors, described herein fulfill these needs as well as others. Summary of the Application

In some embodiments, the disclosure provides for a method of treating polycythemia in a subject, the method comprising administering to the subject a pharmaceutical composition comprising one or more glycine transporter 1 (GlyT1) inhibitor, or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more GlyT 1 inhibitor or its salt. In some embodiments, the disclosure provides for a method of preventing, treating, or reducing the progression rate and/or severity of polycythemia in a subject, the method comprising administering to the subject a pharmaceutical composition comprising one or more glycine transporter 1 (GlyT1) inhibitor, or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more GlyT 1 inhibitor or its salt. In some embodiments, the disclosure provides for a method of preventing, treating, or reducing the progression rate and/or severity of one or more complications of polycythemia in a subject, the method comprising administering to the subject a pharmaceutical composition comprising one or more GlyT1 inhibitor, or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more GlyT 1 inhibitor or its pharmaceutically acceptable salt. In some embodiments, the one or more complications of polycythemia is selected from the group consisting of: pulmonary embolisms, transient ischemic attacks, transient visual defects, deep vein thrombosis, splenomegaly, hepatomegaly, myelofibrosis, and acute myeloid leukemia. In some embodiments, the myelofibrosis is selected from the group consisting of low-risk myelofibrosis, intermediate-risk myelofibrosis, high-risk myelofibrosis, primary myelofibrosis, post-essential thrombocythemia myelofibrosis, and post-polycythemia vera myelofibrosis. In some embodiments, the polycythemia is primary polycythemia. In some embodiments, the primary polycythemia is polycythemia vera. In some embodiments, the primary polycythemia is pure erythrocytosis. In some embodiments, the primary polycythemia is primary familial polycythemia.

In some embodiments, the polycythemia is secondary polycythemia. In some embodiments, the secondary polycythemia is associated with a disorder selected from the group consisting of hypoxia, central hypoxic process, lung disease, right-to-left cardiopulmonary vascular shunts (congenital or acquired), heart disease, heart failure, carbon monoxide poisoning, smoker’s erythrocytosis, high-altitude habitat, renal disease, kidney transplant, hemoglobinopathy with high-oxygen-affinity, decreased levels of erythrocyte 2,3,-DPG, bisphosphoglycerate mutase deficiency, methemoglobinemia, hereditary ATP increase, oxygen sensing pathway gene mutations, tumor, drug-induced secondary polycythemia, adrenal cortical hypersecretion, and idiopathic polycythemia. In some embodiments, the lung disease is selected from the group consisting of chronic lung disease, interstitial lung disease, chronic obstructive pulmonary disease (COPD), Pickwickian syndrome, emphysema, pulmonary fibrosis, sleep apnea, hypoventilation syndromes, and obesity hypoventilation syndrome. In some embodiments, the heart disease is selected from the group consisting of cyanotic heart disease and congenital heart disease. In some embodiments, the renal disease is selected from the group consisting of local renal hypoxia, renal artery stenosis, cysts, polycystic kidney disease, hydronephrosis, nephrotic syndrome, diffuse parenchymal disease, Bartter’s syndrome, end-stage renal disease, long-term hemodialysis, and post-renal transplant erythrocytosis. In some embodiments, the oxygen sensing pathway gene mutations are selected from the group consisting of EpoR, VHL, HIF2A, and PHD2. In some embodiments, the tumor is a tumor with an excessive production of erythropoietin or erythropoietin related factors. In some embodiments, the tumor is selected from the group consisting of renal cell carcinoma, renal tumors, hepatocellular carcinoma, pheochromocytoma, cerebellar hemangioblastoma, uterine leiomyoma, ovarian carcinoma, meningioma, parathyroid carcinoma, and parathyroid adenoma. In some embodiments, the drug-associated secondary polycythemia is selected from the group consisting of erythropoietin administration, androgen administration, anabolic steroid administration, synthetic testosterone administration, protein injections, gentamicin administration, and methyldopa administration. In some embodiments, the polycythemia is relative polycythemia. In some embodiments, the relative polycythemia is selected from the group consisting of Gaisbock’s syndrome, spurious polycythemia, or stress erythrocytosis. In some embodiments, the polycythemia is Chuvash polycythemia.

In some embodiments, the disclosure provides for a method of inhibiting heme synthesis in a subject with polycythemia, comprising administering to a subject a GlyT1 inhibitor, or a pharmaceutically acceptable salt thereof, or a prodrug of the GlyT 1 inhibitor or its pharmaceutically acceptable salt. In some embodiments, the heme synthesis is inhibited in a dose dependent manner. In some embodiments, the disclosure provides for a method of inhibiting hemoglobin synthesis in a subject with polycythemia, comprising administering to a subject a GlyT1 inhibitor, or a pharmaceutically acceptable salt thereof, or a prodrug of the GlyT 1 inhibitor or its pharmaceutically acceptable salt. In some embodiments, the hemoglobin synthesis is inhibited in a dose dependent manner. In some embodiments, the disclosure provides for a method of inhibiting red blood cell synthesis in a subject with polycythemia, comprising administering to a subject a GlyT1 inhibitor, or a pharmaceutically acceptable salt thereof, or a prodrug of the GlyT1 inhibitor or its pharmaceutically acceptable salt. In some embodiments, the red blood cell synthesis is inhibited in a dose dependent manner. In some embodiments, the disclosure provides for a method of decreasing the red blood cell count in a subject with polycythemia, comprising administering to a subject a GlyT1 inhibitor, or a pharmaceutically acceptable salt thereof, or a prodrug of the GlyT1 inhibitor or its pharmaceutically acceptable salt. In some embodiments, the red blood cell count is decreased in a dose dependent manner. In some embodiments, the subject has hematocrit levels that are at least 10%, 20%, 30%, 40%, or 50% more than hematocrit levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has hematocrit levels that are at least 48%. In some embodiments, the subject has hematocrit levels that are at least 49%. In some embodiments, the subject has red blood cell mass levels that are at least 10%, 20%, 30%, 40%, or 50% more than red blood cell mass levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has red blood cell mass levels that are at least 25% above mean normal predicted value. In some embodiments, the subject has a red blood cell count that is at least 10%, 20%, 30%, 40%, or 50% more than red blood cell count in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has a red blood cell count greater than 5.1 x10 ¹² /L. In some embodiments, the subject has a red blood cell count greater than 5.3 x10 ¹² /L. In some embodiments, the subject has hemoglobin levels that are at least 10%, 20%, 30%, 40%, or 50% more than hemoglobin levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has hemoglobin levels that are greater than 16.0 g/dL. In some embodiments, the subject has hemoglobin levels that are greater than 16.5 g/dL. In some embodiments, the method decreases the subject’s hematocrit levels by at least 10% ( e.g ., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method decreases the subject’s hematocrit levels to less than 48%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 10% (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method decreases the subject’s red blood cell mass by at least 10% (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method decreases the subject’s hemoglobin levels by at least 10% (e.g, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method decreases the subject’s hemoglobin levels to less than 16 g/dL. In some embodiments, the subject’s iron levels are maintained. In some embodiments, the subject’s stored iron levels are increased. In some embodiments, the method decreases the incidence of iron deficiency in the subject. In some embodiments, the method decreases the incidence of iron deficiency by at least 10% (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method improves iron deficiency in the subject. In some embodiments, the method improves iron deficiency in the subject by at least 10% (e.g, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the subject has an increased spleen size. In some embodiments, the method reduces the subject’s spleen size. In some embodiments, the method reduces the subject’s spleen size by at least 10% (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%).

In some embodiments, the subject has a mutation in Janus Kinase 2 (JAK2). In some embodiments, the mutation in JAK2 is a JAK2 V617F exon 14 mutation. In some embodiments, the mutation in JAK2 is a JAK2 exon 12 mutation. In some embodiments, the mutation in JAK2 is a gain-of- function mutation. In some embodiments, the subject’s JAK2 enzyme activity is increased. In some embodiments, the subject has a mutation in Tet Methylcytosine Dioxygenase 2 (TET2) or Nuclear Factor Erythroid 2 (NFE2). In some embodiments, the subject has a mutation in gene selected from the group consisting of VHL, EPO, EPOR, ELG1, EPAS1, HIF2A, and BPGM. In some embodiments, the subject has a high oxygen affinity variant selected from the group consisting of hemoglobin B (HBB) and hemoglobin A (HBA).

In some embodiments, the subject has an inadequate response to hydroxyurea. In some embodiments, the subject is intolerant to hydroxyurea. In some embodiments, the method reduces the subject’s need for therapeutic phlebotomies. In some embodiments, the method reduces the subject’s need for therapeutic phlebotomies by at least 10% (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method eliminates the subject’s need for therapeutic phlebotomies. In some embodiments, the method reduces the risk of thromboembolic events in the subject. In some embodiments, the thromboembolic event is arterial thrombosis. In some embodiments, the thromboembolic event is venous thrombosis. In some embodiments, the method reduces the risk of blurred vision in the subject. In some embodiments, the method reduces the risk of blurred vision in the subject by at least 10% ( e.g ., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method reduces the risk of headaches in the subject. In some embodiments, the risk of headaches in the subject by at least 10% (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method increases the subject’s quality of life. In some embodiments, the method increases the subject’s quality of life by at least 1% (e.g., 1%, 2%, 3%, 4%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%).

In some embodiments, the method further comprises administering to the subject an additional active agent and/or supportive therapy. In some embodiments, the additional active agent and/or supportive therapy is selected from the group consisting of: Hydroxyruea (e.g., Droxia®, Hydrea®), Interferon alpha, Interferon alpha-2b (e.g., Intron® A), Ruxolitinib (e.g., Jakafi®), Busulfan (e.g., Busulfex®, Myleran®), radiation treatment, hepcidin mimetics (e.g., PTG-300), matriptase-2 inhibitors, ferroportin inhibitors, JAK inhibitors, BET inhibitors, MDM2 inhibitors, and HD AC inhibitors.

In certain embodiments, the GlyT1 inhibitor is a compound of Formula I,

Formula I, wherein Ar is unsubstituted or substituted aryl or 6- membered heteroaryl containing one, two or three nitrogen atoms, wherein the substituted aryl and the substituted heteroaryl groups are substituted by one or more substituents selected from the group consisting of hydroxy, halogen, NO ₂ , CN, (C ₁ -C ₆ )-alkyl, (C ₁ -C ₆ )-alkyl substituted by halogen, (C ₁ -C ₆ )-alkyl substituted by hydroxy, (CH ₂ )n — (C ₁ -C ₆ )-alkoxy, (C ₁ - C ₆ )-alkoxy substituted by halogen, NR ⁷ R ⁸ , C(O)R ⁹ , SO2R ¹⁰ , and — C(CH ₃ )=NOR ⁷ , or are substituted by a 5-membered aromatic heterocycle containing 1 -4 heteroatoms selected from N and O, which is optionally substituted by (C ₁ -C ₆ )-alkyl;R ¹ is hydrogen or (C ₁ -C ₆ )-alkyl; R ² is hydrogen, (C ₁ -C ₆ )-alkyl, (C ₂ -C ₆ )-alkenyl, (C ₁ -C ₆ )-alkyl substituted by halogen, (C ₁ -C ₆ )- alkyl substituted by hydroxy, (CH2)n — (C ₃ -C ₇ )-cycloalkyl optionally substituted by (C ₁ -C ₆ )- alkoxy or by halogen, CH(CH ₃ ) — (C ₃ -C ₇ )-cycloalkyl, (CH ₂ ) _n+1 — C(O) — R ⁹ , (CH ₂ ) _n+1 — CN, bicyclo[2.2.1]heptyl, (CH ₂ ) _n+1 — O — (C ₁ -C ₆ )-alkyl, (CH ₂ ) _n -heterocycloalkyl, (CH ₂ ) _n -aryl or (CH ₂ ) _n -5 or 6-membered heteroaryl containing one, two or three heteroatoms selected from the group consisting of oxygen, sulphur or nitrogen wherein aryl, heterocycloalkyl and heteroaryl are unsubstituted or substituted by one or more substituents selected from the group consisting of hydroxy, halogen, (C ₁ -C ₆ )-alkyl and (C ₁ -C ₆ )-alkoxy; R ³ , R ⁴ and R ⁶ are each independently hydrogen, hydroxy, halogen, (C ₁ -C ₆ )-alkyl, (C ₁ -C ₆ )-alkoxy or O — (C ₃ -C ₆ )-cycloalkyl; R ⁵ is NO ₂ , CN, C(O)R ⁹ or SO ₂ R ¹⁰ ; R ⁷ and R ⁸ are each independently hydrogen or (C1-C6)-alkyl; R ⁹ is hydrogen, (C ₁ -C ₆ )-alkyl, (C ₁ -C ₆ )-alkoxy or NR ⁷ R ⁸ ; R ¹⁰ is (C ₁ -C ₆ )-alkyl optionally substituted by halogen, (CH ₂ ) _n — (C ₃ -C ₆ )-cycloalkyl, (CH ₂ ) _n — (C ₃ - C ₆ )-alkoxy, (CH ₂ ) _n -heterocycloalkyl or NR ⁷ R ⁸ ; n is 0, 1, or 2; or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In certain embodiments, GlyT 1 inhibitor is a compound having a formula of , bitopertin, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In certain embodiments, the GlyT1 inhibitor is a compound of Formula II, Formula II, wherein Ri represents a heteroaryl selected from the group consisting of: imidazolyl, thiazolyl, pyridyl, oxazolyl, pyrazolyl, triazolyl, oxadiazolyl, quinolinyl, isoxazolyl, pyrroloimidazoyl, and thiadiazole, wherein said heteroaryl is optionally substituted by one or more substituents selected from -OH, -NR ₇ R ₈ , halogen, (C ₁ - C ₈ )alkyl, (C ₃ -C ₁₀ )cycloalkyl, (C ₁ - C ₈ )alkoxy, (C ₁ - C ₁₂ )alkoxyalkyl, (C ₁ - C ₈ )hydroxy alkyl, (C ₆ - C ₁₄ )aryl and benzyl; R2, R ₃ and A independently represent H or (C ₁ -C ₈ )alkoxy, wherein said alkyl is optionally substituted by one or more -OH, (C ₁ -C ₈ )alkoxy, -NR ₇ R ₈ or halogen; Q represents -(CH ₂ ) _n -, where n = 1, 2, 3 or 4 or -(CH ₂ ) _m -O-, where m = 2, 3 or 4; Z represents (C ₆ -C ₁₄ )aryl, (C ₁ -C ₈ )alkyl or (C ₃ - C ₈ )cycloalkyl; R ₄ and R ₅ each independently represent H, halogen, (C ₁ -C ₈ )alkyl, (C ₆ -C ₁₄ )aryl, (C ₆ -C ₁₄ )aryloxy, (C ₁ - C ₈ )alkoxy, (3-10 membered)heterocycloalkyl or (C ₃ - C ₈ ) cycloalkoxy ; wherein R ₄ and R ₅ are optionally substituted by one or more -OH, (C ₁ - C ₈ )alkoxy, -NR ₇ R ₈ or halogen; Y represents -R ₆ , - (CH ₂ )o-R ₆ , -C(R ₆ ) ₃ or -CH (R ₆ ) ₂ , wherein 0 = 1, 2 or 3; R ₆ represents H, (C ₆ -C ₁₄ )aryl, (C ₁ - ₁₀ )alkyl, (C ₃ -C ₁₀ )cycloalkyl, (C ₅ -C ₁₈ )bicycloalkyl, (C ₅ -C ₁₈ )tricycloalkyl, (3-10 membered)heterocycloalkyl, (5-10 membered)heteroaryl, - C(=O)NR ₇ R ₈ , or -C(=O)OR ₇ , wherein said R ₆ groups can optionally be substituted with one or more X groups; wherein X = -OH, (C ₁ -C ₈ )alkoxy, -NR ₁₁ R ₁₂ , -SO ₂ R ₁₀ , -C(=O)R ₁₀ , halogen, cyano, (C ₁ - C ₈ )alkyl, (C ₁ - C ₁₀ )alkoxyalkyl, (5-10 membered)heteroaryl, (C ₆ -C ₁₄ )aryl, (C ₆ -C ₁₄ )aryloxy, benzyl, or (C1- C ₈ )hydroxyalkyl; wherein R ₇ and R ₈ independently represent H, (C ₁ -C ₈ )alkyl, (C ₃ - C8)cycloalkyl, (5-10 membered)heterocycloalkyl, (C ₁ -C ₈ )hydroxyalky, (5-10 membered)heteroaryl or (C ₁ - C ₁₀ )alkoxyalkyl; wherein R ₇ and R ₈ may optionally be substituted by one or more X groups; or R ₇ and R ₈ together with the nitrogen in which they may be attached may form a (3- 10 membered)heterocycloalkyl group optionally substituted by one or more X groups; wherein R ₁₀ represents (C ₁ - C ₈ )alkyl, (C ₃ -C ₈ )cycloalkyl, (3-10 membered)heterocycloalkyl, (C ₁ - C ₈ )hydroxyalky, (5-10 membered)heteroaryl or (C ₁ - C ₁₀ )alkoxyalkyl; wherein Rn and R ₁₂ independently represent H, (C ₁ -C ₈ )alkyl, (C ₃ - C ₈ )cycloalkyl, (5-10 membered)heterocycloalkyl, (C ₁ -C ₈ )hydroxyalky, (5-10 membered)heteroaryl or (C ₁ - C ₁₀ )alkoxyalkyl; or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt. In certain such embodiments, the GlyT1 inhibitor is a compound having a formula of

, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt. In other such embodiments, the GlyT1 inhibitor is a compound having a formula of , PF-3463275, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In certain embodiments, the GlyT1 inhibitor is a compound of Formula III, Formula III, wherein Z ¹ is selected from the group consisting of C _1-4 alkyl, C _3-6 CycloaIkVl, C _1-4 alkoxy, C _1-4 alkylthio, haloC _1-4 alkyl, phenyl, haloC _1-4 alkoxy, halophenyl, C _1-4 alkylsulfoxy, C _1-4 alkylsulfonyl, bromo and chloro; Z ² is selected from the group consisting of hydrogen, halogen, cyano, C _1-4 alkyl, phenyl, haloC _1-4 alkyl, haloC ₁ - ₄ alkoxy, halophenyl, C _1-4 alkoxyC _1-4 alkyl and C _3-6 cycloalkyl; Z ³ is selected from the group consisting of hydrogen, halogen, C _1-4 alkyl, C _1-4 alkoxy, C _1-4 alkylthio, haloC _1-4 alkyl, haloC ₁ - ₄ alkoxy, and C _3-6 cycloalkyl; Z ⁴ is selected from the group consisting of hydrogen, halogen, C1-3alkyl, haloC _1-4 alkyl, C _1-4 alkoxy, C _1-4 alkylthio, phenyl, halo C _1-4 alkoxy, halophenyl, C ₁ - ₄ alkoxy C _1-4 alkyl and C _3-6 cycloalkyl; Z ⁵ is selected from the group consisting of hydrogen, fluoro, chloro, bromo, iodo, hydroxy, C _1-4 alkyl, C _1-4 aIkoxy, C _1-4 alkylthio, phenyl, haloC ₁ - ₄ alkyl, haloC _1-4 alkoxy, halophenyl, C _1-4 alkoxyC _1-4 alkyl and C _3-6 Cyeloalkyl; whereby if more than one of Z ¹ to Z ⁵ is methoxy, then only Z ¹ and Z ⁵ are methoxy R ³ and R ⁴ are independently selected from hydrogen and C _1-4 alky 1, optionally substituted with one or more groups Y; or R ³ and R4 together with the nitrogen atom to which they are attached form a saturated or partially unsaturated A-, 5- 6-or 7-membered carbocyclic ring optionally substituted with a group Y'; Y is selected from the group consisting of C _1-4 alkoxy, hydroxy, haloC _1-4 alkoxy and C _3-5 cycloalkyl; Y' is selected from the group consisting of C _1-4 alkyl, C ₁ - ₄ alkoxy, halogen, hydroxy, haloC _1-4 alkoxy, C _3-5 Cycloalkyl and C ₈ -ioaryl or Y' forms a -CH2- or -CH2-CH2- bridge between two atoms on the A-, 5-, 6- or 7-membered carbocyclic ring;

R ⁵ and R ⁶ are independently C _1-4 alkyl, optionally substituted with one or more groups X; or R ⁵ and R ⁶ together with the carbon atom to which they are attached form a saturated 5- or 6- membered ring carbocyclic optionally substituted with one or more groups X', in the case of R ⁵ and R6 together with the carbon atom to which they are attached forming a 5- membered saturated carbocyclic ring, that ring may optionally further comprising an additional heteroatom group selected from O, N and S(O)m, where m = 0, 1 or 2; X is selected from the group consisting of halogen, hydroxy, C _1-4 alkoxy, haloC _1-4 alkyl, haloC _1-4 alkoxy and C5- _l oaryl; and X' is selected from the group consisting of halogen, hydroxy, C _1-4 alkyl, C ₁ - ₄ alkoxy, haloC _1-4 alkyl, haloC _1-4 alkoxy and C ₈ -ioaryl; whereby R ³ , R ⁴ , R ⁵ and R ⁶ are not all simultaneously unsubstituted methyl; with the provisos that when simultaneously Z ¹ is propyloxy, Z ³ is chloro, Z ² =Z ⁴ =Z ⁵ =H, and R ⁵ and R ⁶ are both methyl, then R ³ and R ⁴ together with the nitrogen atom to which they are attached do not form a 2-methylpyrrolidine group; when simultaneously Z ¹ is methyl, Z ³ is methoxy, Z ² =Z4=Z5=H, and R ⁵ and R ⁶ are both methyl, then R ³ and R ⁴ together with the nitrogen atom to which they are attached do not form a pyrrolidine group, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt. In certain such embodiments, the GlyT 1 inhibitor is a compound having a formula of or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In certain embodiments, the GlyT1 inhibitor is a compound of Formula IV, Formula IV, wherein Z is (CH ₂ )n, O, S, SO, SO ₂ or N-R ₅ ; n is

0, 1 or 2; X represents 1-3 substituents independently selected from hydrogen, halogen, (C ₁ - ₆ )alkyioxy, (C _3-6 )cycloalkyloxy, (C _6-12 )aryloxy, (C _6-12 )aryl, thienyl, SR ₆ , SOR ₆ , SO ₂ R ₆ , NR ₆ R ₆ , NHR ₆ , NH ₂ , NHCOR ₆ , NSO ₂ R ₆ , CN, COOR ₆ and ( C _1-4 ) alkyl, optionally substituted with halogen, (C _6-12 )aryl, (C _1-6 )alkyloxy or (C _6-12 )aryloxy; or 2 substituents at adjacent positions together represent a fused (C _5-6 )aryl group, a fused (C _5-6 )cycloalkyl ring or O-

(CH ₂ ) _m -O; m is 1 or 2; Y represents 1-3 substituents independently selected from hydrogen, halogen, (C _1-4 )alkyloxy, SR ₆ , NR ₆ R ₆ and (C _1-4 )alkyl, optionally substituted with halogen; Ri is COOR ₇ or CONR ₈ R ₉ ; R ₂ and R6 are (C _1-4 )al ky l ; R ₃ , R ₄ are R ₅ are independently hydrogen or (C _1-4 )alkyl; R ₇ , R ₈ and R ₉ are independently hydrogen, (C _1-4 )alkyl, (C _6-12 )aryl or arylalkyl, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt. In certain such embodiments, the GlyT1 inhibitor is a compound having a formula of , or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt. In certain embodiments, the GlyT1 inhibitor is a compound of Formula V,

Formula V, wherein n is an integer from 1 to 3; R ¹ and R ² are independently selected from hydrogen, alkyl, haloalkyl, alkoxy, haloalkoxy, aryl, heteroaryl, cycloalkyl, or heterocyclyl wherein the aforementioned rings are optionally substituted with R ^a , R ^b , or R ^c independently selected from alkyl, halo, haloalkyl, alkoxy, haloalkoxy, hydroxy, cyano, monosubstituted amino, or disubstituted amino; or R ¹ and R ² , when attached to the same carbon atom, can combine to form cycloalkyl or monocyclic saturated heterocyclyl to give a spiro ring wherein the cycloalkyl or monocyclic saturated heterocyclyl can be optionally substituted with R ^d , R ^c , or R ^f independently selected from alkyl, alkoxy, fluoro, fluoroalkyl, fluoroalkoxy, hydroxy, monosubstituted amino, or disubstituted amino; or R ¹ and R ² , when attached to carbon atoms 2 and 5 or 3 and 6 positions of the piperazine ring, can combine to form -C ₁ -C ₃ - alkylene chain wherein one of the carbon atoms in the alkylene chain is optionally replaced by a -NR-, -O-, -S(O)n- (where R is hydrogen or alkyl and n is 0-2) and further wherein one or two hydrogen atoms in the alkylene chain can be optionally substituted with one or two alkyl; R ³ , R ⁴ and R ⁵ are independently hydrogen, alkyl, fluoro, or fluoroalkyl; and Ar ¹ and Ar ² are independently aryl, heteroaryl, cycloalkyl, or heterocyclyl where each of the aforementioned ring is optionally substituted with R ^g , R ^h or R ⁱ where R ^g is alkyl, -C=C- R ⁶ (where R ⁶ is aryl or heteroaryl), halo, haloalkyl, haloalkoxy, alkylthio, cyano, alkoxy, amino, monosubstituted amino, disubstituted amino, sulfonyl, acyl, carboxy, alkoxycarbonyl, hydroxyalkyl, alkoxyalkyl, aminoalkyl, hydroxyalkoxy, alkoxyalkoxy, aminoalkoxy, aminosulfonyl, aminocarbonyl, or acylamino and R ^h and R ⁱ are independently selected from alkyl, halo, haloalkyl, haloalkoxy, alkylthio, cyano, alkoxy, amino, monosubstituted amino, disubstituted amino, sulfonyl, acyl, carboxy, alkoxycarbonyl, hydroxyalkyl, alkoxyalkyl, aminoalkyl, hydroxyalkoxy, alkoxyalkoxy, aminoalkoxy, aminosulfonyl, aminocarbonyl, acylamino, aryl., heteroaryl, cycloalkyl, or heterocyclyl where the aromatic or alicyclic ring-in R ^g , R ^h and R ⁱ is optionally substituted with R ^j R ^k , or R ¹ which are independently selected from alkyl, halo, haloalkyl, haloalkoxy, alkylthio, cyano, alkoxy, amino, monosubstituted amino, disubstituted amino, sulfonyl, acyl, carbpxy, alkoxycarbonyl, hydroxyalkyl, alkoxyalkyl, aminoalkyl, hydroxyalkoxy, alkoxyalkoxy, aminoalkoxy, aminosulfonyl, aminocarbonyl, or acylamino; or a pharmaceutically acceptable salt thereof provided that: the compound of Formula V is not 2-(4-benzhydrylpiperazin-l- yl)acetic acid, 2-(4- ((4-chlorophenyl)(phenyl)methyl)piperazin-l-yl)acetic acid, 2-((2R,5S)- 4-((R)-(4-(lH- tetrazol-5-yl)phenyl)(3-hydroxyphenyl)methyl)-2,5-dimethylpi perazin-l- yl)acetic acid, or 2- ((2R,5S)-4-((R)-(4-cyanophenyl)(3-hydroxyphenyl)methyl)-2,5- dimethylpiperazin-l-yl)acetic acid, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt. In certain such embodiments, the

GlyT 1 inhibitor is a compound having a formula of , or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In certain embodiments, the GlyT1 inhibitor is a compound of Formula VI,

Formula VI, wherein A represents a group of general formula N — Ri, a group of general formula N+(O-)R ₁ or a group of general formula N+(R')R ₁ , and in which Ri represents either a hydrogen atom, or a linear or branched (C ₁ -C ₇ )alkyl group optionally substituted with one or more fluorine atoms, or a (C ₄ -C ₇ )cycloalkyl group, or a (C ₃ -C ₇ )cycloalkyl(C ₁ -C ₃ )alkyl group, or a phenyl(C ₁ -C ₃ )alkyl group optionally substituted with one or two hydroxyl or methoxy groups, or a (C ₂ -C ₄ )alkenyl group, or a (C ₂ -C ₄ )alkynyl group; R' represents a linear or branched (C ₁ -C ₇ )alkyl group; X represents a hydrogen atom or one or more substituents chosen from halogen atoms and trifluoromethyl, linear or branched (C1-C4)alkyl and (C ₁ -C ₄ )alkoxy groups; R ₂ represents either a hydrogen atom, or one or more substituents chosen from halogen atoms and trifluoromethyl, (C ₁ -C ₄ )alkyl or (C ₁ -C ₄ )alkoxy groups, or amino groups of general formula NR ₃ R ₄ in which R ₃ and R ₄ each represent, independently of each other, a hydrogen atom or a (C ₁ -C ₄ )alkyl group, or form with the nitrogen atom carrying them a pyrrolidine, piperidine or morpholine ring, or a phenyl group optionally substituted with an atom or a group as defined for the symbol X above, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt. In certain such embodiments, the GlyT1 inhibitor is a compound having a formula of , or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In certain embodiments, the GlyT1 inhibitor is a compound of Formula VII, Formula VII, wherein R ¹ is — (CH ₂ ) _{n —} R ^1a , wherein n is independently 0-6, and R ^1a is selected from the group consisting of:(l) C _1-6 alkyl, which is unsubstituted or substituted with 1 -6 halogen, hydroxy, (2) phenyl substituted with R ^2a , R ^2b and R ^2c , (3) C _3-6 cycloallyl, which is unsubstituted or substituted with C _1-6 alkyl, 1-6 halogen, hydroxy or — NR ¹⁰ R ¹¹ , (4) — O — C _1-6 alkyl, which is unsubstituted or substituted with 1-6 halogen, hydroxy or — NR ¹⁰ R ¹¹ , (5) — CO2R ⁹ , wherein R9 is independently selected from: (a) hydrogen, (b) — C _1-6 alkyl, which is unsubstituted or substituted with 1-6 fluoro, (c) benzyl, and (d) phenyl, (6) — NR ¹⁰ R ¹¹ , wherein R ¹⁰ and R ¹¹ are independently selected from: (a) hydrogen, (b) — C _1-6 alkyl, which is unsubstituted or substituted with hydroxy, 1-6 fluoro or — NR ¹² R ¹³ , where R ¹² and R ¹³ are independently selected from hydrogen and — C _1-6 alkyl, (c) — C _3-6 cycloalkyl, which is unsubstituted or substituted with hydroxy, 1 -6 fluoro or — NR ¹² R ¹³ , (d) benzyl, (e) phenyl, and (7) — CONR ¹⁰ R ¹¹ ; R2 is selected from the group consisting of: (1) phenyl, which is substituted with R ^2a , R ^2b and R ^2c , (2) C _1-8 alkyl, which is unsubstituted or substituted with 1-6 halogen, hydroxy, — NR ¹⁰ R ¹¹ , phenyl or heterocycle, where the phenyl or heterocycle is substituted with R ^2a , R ^2b and R ^2c , (3) C _3-6 Cycloalkyl, which is unsubstituted or substituted with 1-6 halogen, hydroxy or — NR ¹⁰ R ¹¹ , and (4) — C _1-6 alkyl- ( C _3-6 cycloalkyl), which is unsubstituted or substituted with 1-6 halogen, hydroxy or — NR ¹⁰ R ¹¹ ; R ^2a , R ^2b and R ^2c are independently selected from the group consisting of: (1) hydrogen, (2) halogen, (3) — C _1-6 alkyl, which is unsubstituted or substituted with: (a) 1-6 halogen, (b) phenyl, (c) C _3-6 cycloalkyl, or (d) — NR ¹⁰ R ¹¹ , (4) — O — C _1-6 alkyl, which is unsubstituted or substituted with 1-6 halogen, (5) hydroxy, (6) — SCF ₃ , (7) — SCHF ₂ , (8) — SCH ₃ , (9) — CO ₂ R ⁹ , (10) — CN, (11) — SO ₂ R ⁹ , (12) — SO ₂ — NR ¹⁰ R ¹¹ , (13) — NR ¹⁰ R ¹¹ , (14) — CONR ¹⁰ R ¹¹ , and (15) — NO ₂ ; R ³ is selected from the group consisting of: (1) C _1-6 alkyl, which is unsubstituted or substituted with 1-6 halogen, hydroxyl, or — NR ¹⁰ R ¹¹ , (2) C ₃ - ecycloalkyl, which is unsubstituted or substituted with 1-6 halogen, hydroxyl or — NR ¹⁰ R ¹¹ , R ⁴ and R ⁵ are independently selected from the group consisting of: (1) hydrogen, and (2) C ₁ - ₆ alkyl, which is unsubstituted or substituted with halogen or hydroxyl, or R ⁴ and R ⁵ taken together form a C _3-6 cycloalkyl ring; A is selected from the group consisting of: (1) — O — , and (2) — NR ¹⁰ — ; m is zero or one, whereby when m is zero R ² is attached directly to the carbonyl; and pharmaceutically acceptable salts thereof and individual enantiomers and diastereomers thereof, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt. In certain such embodiments, the GlyT 1 inhibitor is a compound having a formula of , or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt. In certain embodiments, the GlyT1 inhibitor is a compound of Formula VIII,

Formula VIII, wherein R ¹ is phenyl independently substituted from 1 to 5 times with halogen, C ₁ -C ₃ alkyl, C ₃ -C ₆ cycloalkyl, OR ⁹ , or SR ¹⁰ , wherein C ₁ -C ₃ alkyl and C ₃ -C ₆ cycloalkyl are optionally substituted with 1 to 10 times with R ⁷ ; R ² is H; R ³ and R4 are each individually H or CH ₃ ; R ⁵ is selected from the group consisting of: (1) hydrogen, (2) C ₁ -C ₆ alkyl which is optionally substituted from 1 to 11 times with R ⁷ , (3) gem-dialkyl, and (4) gem-dihalo; or two R ⁵ substituents on the same carbon, together with the carbon atom to which they are attached, may form a 3-, 4-, or 5-membered cycloalkyl optionally substituted from 1 to 10 times with R ⁷ ; or two R ⁵ substituents on adjacent carbons of the ring to which they are attached, together may form a 3-, 4-, 5- or 6- membered cycloalkyl optionally substituted from 1 to 10 times with R ⁷ ; R ⁶ is wherein E, F, and G are each independently nitrogen or carbon and R ^6a is C ₁ -C ₂ alkyl, which is optionally substituted 1 to 5 times with halogen or deuterium; R ⁷ is selected from the group consisting of: (1) hydrogen, (2) halogen, (3) deuterium, (4) gem-dialkyl, (5) gem-dihalo, (6) —OR ⁹ , — NR ¹¹ R ¹² , — NR ¹¹ C(O) _P R ¹⁰ , — S(O) _P R ¹⁰ , — CN, — NO2, — C(O) _P R ¹⁰ , — C(O)NR ¹¹ R ¹² , or — NR ¹¹ C(S)R ¹⁰ , and (7) oxo or thio; R ⁸ is selected from the group consisting of: (1) hydrogen, (2) halogen, (3) C ₁ -C ₆ alkyl, C ₂ -C ₆ alkenyl, C ₂ -C ₆ alkynyl, C ₃ - C ₇ cycloalkyl, or C ₄ -C ₇ cycloalkylalkyl, wherein each of the C ₁ -C ₆ alkyl, C ₂ -C ₆ alkenyl, C ₂ - C ₆ alkynyl, C ₃ -C ₇ cycloalkyl, and C ₄ -C ₇ cycloalkylalkyl is independently and optionally substituted from 1 to 11 times with R ⁷ , or (4) — OR ⁹ , — NR ¹¹ R ¹² , — NR ¹¹ C(O) _p R ¹⁰ , — S(O) _p R ¹⁰ , — CN, — NO2, — C(O) _P R ¹⁰ , — C(O)NR ¹¹ R ¹² , or — NR ¹¹ C(S)R ¹⁰ ; R ⁹ is selected from the group consisting of hydrogen, C ₁ -C ₄ alkyl, C ₃ -C ₇ cycloalkyl, C ₄ -C ₇ cycloalkylalkyl, — C(O)NR ¹¹ R ¹² , and — C(O) _p R ¹⁰ , wherein each of C ₁ -C ₄ alkyl, C ₃ -C ₇ cycloalkyl, and C ₄ -C ₇ cycloalkylalkyl is optionally substituted from 1 to 11 times with R ⁷ ; R ¹⁰ is selected from the group consisting of hydrogen, C ₁ -C ₄ alkyl, C ₃ -C ₇ cycloalkyl C ₄ -C ₇ cycloalkylalkyl, aryl, and heteroaryl, wherein each of C ₁ -C ₄ alkyl, C ₃ -C ₇ cycloalkyl, and C ₄ -C ₇ cycloalkylalkyl is optionally substituted from 1 to 11 times with substituents as defined in R7 and aryl or heteroaryl is optionally substituted from 1 to 10 times with R ⁸ ; R ¹¹ and R ¹² are each independently selected from the group consisting hydrogen, C ₁ -C ₄ alkyl, C ₃ -C ₇ cycloalkyl, C ₄ -C ₇ cycloalkylalkyl, aryl, and heteroaryl, wherein each of C ₁ -C ₄ alkyl, C ₃ -C ₇ cycloalkyl, and C ₄ -C ₇ cycloalkylalkyl is optionally substituted from 1 to 11 times with substituents as defined in R ⁷ and aryl or heteroaryl is optionally substituted from 1 to 10 times with R ⁸ , or R ¹¹ and R ¹² are taken together with the nitrogen to which they are attached to form a saturated or partially saturated monocyclic or fused bicyclic heterocycle optionally substituted from 1 to 11 times with R ⁷ ; A is ; X is N; Y is N; p is 1, or 2; and m is 0; with the following provisos that: R ⁶ cannot be (a) 1H-1,2,3-triazol-4-yl, or (b) 5- methylisoxazol-4-yl; or an oxide thereof, a pharmaceutically acceptable salt of the compound or its oxide, or an individual enantiomer or diastereomer thereof.

In certain embodiments, the GlyT 1 inhibitor is a compound selected from any of the following:

_’ , and , or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In certain embodiments, the GlyT1 inhibitor is a compound of formula IX, Formula IX, wherein R ¹ represents phenyl or a 5 or 6 membered monocyclic heteroaryl having 1, 2, or 3 heteroatoms independently selected from O, N or S, wherein the phenyl or the heteroaryl is optionally substituted with one or more R ³ ; R ² represents aryl, a 5 or 6 membered monocyclic heteroaryl or a 8 to 10 membered bicyclic heteroaryl, the mono- or bicyclic heteroaryl having 1 , 2, or 3 heteroatoms independently selected from O, N or S, wherein the aryl or the heteroaryl is optionally substituted with one or more R ⁴ ; R ³ is a halogen, a C _1-4 -alkyl or a C _3-6 -cycloalkyl, wherein the C _1-4 -alkyl or the C ₃ - ₆ -cycloalkyl is optionally substituted with one or more halogens; and R ⁴ is a halogen, — CN,

C ₁₄ -alkyl, C _3-6 -cycloalkyl, — C _1-3 -alkyl — C _3-6 -cycloalkyl or — O — C _1-6 alkyl, wherein the C ₁ - ₄ -alkyl, C _3-6 -cycloalkyl, — C _1-3 -alkyl — C _3-6 -cycloalkyl or the — O — C _1-6 -alkyl is optionally substituted with one or more halogens; or a pharmaceutically acceptable salt thereof, or a tautomer or stereoisomer of the compound or its pharmaceutically acceptable salt, or a mixture of any of the foregoing.

In certain embodiments, the GlyT 1 inhibitor is a compound of formula X, Formula X, wherein R ¹ is selected from the group consisting of a) 5 or

6 membered monocyclic heteroaryl, having 1 , 2, 3 or 4 heteroatoms independently selected from the group consisting of O, N and S(O)r, b) 5 or 6 membered monocyclic partially saturated heterocycloalkyl, having 1 , 2 or 3 heteroatoms independently selected from the group consisting of O, N and S(O)r, and c) 9 or 10 membered bicyclic heteroaryl, having 1 , 2 or 3 heteroatoms independently selected from the group consisting of O, N and S(O) _r , wherein r is 0, 1 or 2; wherein each of said groups a), b) and c) is optionally substituted with 1 or more substituents independently selected from the group consisting of C _1-4 -alkyl-, C ₁₄ - alkyl-O — , oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, C _3-6 -cycloalkyl- and C _3-6 - cycloalkyl-O — and in case a substituent is attached to a nitrogen ring atom said substituent is selected from the group consisting of C _1-4 -alkyl-, C _1-4 -alkyl-CO — , C _3-6 -cycloalkyl- and C _3-6 - cycloalkyl-CO — , and wherein each of said C ₁₄ -alkyl-, C ₁₄ -alkyl-O — , C _1-4 -alkyl-CO — , oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, C _3-6 -cycloalkyl-, C _3-6 -cycloalkyl-CO — or C ₃ - ₆ -cycloalkyl-O — substituents may be substituted by 1 or more substituents independently selected from the group consisting of fluoro, — CF ₃ , — CHF ₂ , — CH ₂ F and — CN; R ² is selected from the group consisting of hydrogen, C _1-4 -alkyl-, C _1-4 -alkyl-O — , — CN and C _3-6 - cycloalkyl-, wherein each of said C _1-4 -alkyl-, C ₁₄ -alkyl-O — and C _3-6 -cycloalkyl-group may be optionally substituted with 1 , 2, 3 or more substituents independently selected from the group consisting of fluoro, — CF ₃ , — CHF ₂ , — CH ₂ F and — CN; R ³ is selected from the group consisting of C _1-6 -alkyl-O — , C _3-6 -cycloalkyl-O — , morpholino, pyrazolyl and a 4 to 7 membered, monocyclic heterocycloalkyl-O — with 1 oxygen atom as ring member and optionally 1 or 2 heteroatoms independently selected from the group consisting of O, N and S(O)s with s=0, 1 or 2, wherein said C _1-6 -alkyl-O — and said C _3-6 -cycloalkyl-O — may be optionally substituted with 1 , 2, 3 or more substituents independently selected from the group consisting of fluoro, — CF ₃ , — CHF ₂ , — CH ₂ F, — CN, C _1-4 -alkyl-, C _3-6 -cycloalkyl-, C _1-6 - alkyl-O — and C _3-6 -cycloalkyl-O — ; R ⁴ is hydrogen; or R ³ and R ⁴ together with the ring atoms of the phenyl group to which they are bound may form a 4, 5 or 6 membered, monocyclic, partially saturated heterocycloalkyl or a heteroaryl each of which having 1, 2 or 3 heteroatoms independently selected from the group consisting of O, N and S(O) _s with s=0, 1 or 2, wherein there must be 1 ring oxygen atom that is directly attached to the ring carbon atom of said phenyl group to which R ³ is attached to in general formula (I); wherein said heterocycloalkyl group may be optionally substituted with 1, 2, 3 or more substituents independently selected from the group consisting of fluoro, — CF ₃ , — CHF ₂ , — CH ₂ F, — CN, C _1-4 -alkyl-, C _3-6 -cycloalkyl-, C _1-6 -alkyl-O — , C _3-6 -cycloalkyl-O — , oxetanyl-O — , tetrahydrofuranyl-O — and tetrahydropyranyl-O — ; R ⁵ is hydrogen; R ⁶ is selected from the group consisting of hydrogen, C _1-4 -alkyl-SO _{2 —} , C _3-6 -cycloalkyl-SO ₂ and — CN; R ⁷ is hydrogen; or one of the pairs a) R ⁶ and R ⁷ or b) R ⁶ and R ⁵ form together with the ring atoms of the phenyl group to which they are bound, a 5 or 6 membered, partially saturated monocyclic heterocycloalkyl group having 1 , 2 or 3 heteroatoms independently selected from the group consisting of O, N and S(O) _u with u=0, 1 or 2, wherein there must be 1 —SO ₂ — member that is directly attached to the ring carbon atom of said phenyl group to which R ⁶ is attached to in general formula (I), wherein said heterocycloalkyl group may be optionally substituted with 1 , 2, 3 or more substituents independently selected from the group consisting of fluoro, — CF ₃ , — CHF ₂ , — CH ₂ F, — CN, C _1-4 -alkyl-, C _1-6 -alkyl-O — and C _3-6 -cycloalkyl-

O — or a pharmaceutically acceptable salt thereof. In certain such embodiments, the GlyT 1

inibitor is a compound having a formula , or a pharmaceutically acceptable salt thereof.

In some embodiments, the GlyT1 inhibitor is a compound of Formula XI,

Formula XI, wherein R ¹ is halogen, — OR ^1' , — SR ^1" , cycloalkyl, cyclic amide, heterocycloalkyl, aryl or 5- or 6-membered heteroaryl containing one, two or three heteroatoms selected from the group consisting of oxygen, sulphur and nitrogen; R ^1' andR ^1" are each independently hydrogen, lower alkyl, lower alkyl substituted by halogen, — (CH ₂ ) _x -cycloalkyl or - (CH ₂ ) _x -aryl; R ² is ^. S(O) ₂ -lower alkyl, - S(O) ₂ NH-lower alkyl,

NO ₂ or CN; is an aromatic or partially aromatic bicyclic amine, having one or two additional N-atoms selected from the group consisting of

wherein one of the additional N-ring atoms of the aromatic or partially aromatic bicyclic amine can be available in form of its oxide R ₃ to RIO are each independently hydrogen, hydroxy, halogen, =O, lower alkyl, cycloalkyl, heterocycloalkyl, lower alkoxy, CN, NO2, NH2, aryl, 5- or 6-membered heteroaryl containing one, two or three heteroatoms selected from the group consisting of oxygen, sulphur and nitrogen, — NH-lower alkyl, — N(lower alkyl)2, cyclic amide, — C(O)-cyclic amide, S-lower alkyl, — S(O)2-lower alkyl, lower alkyl substituted by halogen, lower alkoxy substituted by halogen, lower alkyl substituted by hydroxy, — O — (CH2)y-lower alkoxy, — 0(CH2)yC(O)N(lower alkyl)2, — C(O)-lower alkyl,

— O — (CH2)x-aryl, — O — (CH2)x-cycloalkyl, — O — (CH2)x-heterocycloalkyl, — C(O)O- lower alkyl, — C(O) — NH-lower alkyl, — C(O) — N( lower alkyl)2, 2-oxy-5-aza- bicyclo[2.2.1]hept-5-yl or 3-oxa-8-aza-bicyclo[3.2.1]oct-8-yl; R, R', R" and R'" are each independently hydrogen or lower alkyl; or R' and R'" in group e) together with — (CH2)4 — form a six membered ring; and wherein all aryl-, cycloalkyl-, cyclic amide, heterocycloalkyl- or 5 or 6 membered heteroaryl groups as defined for Rl, Rl', R1 " and R ₃ to RIO are unsubstituted or substituted by one or more substituents selected from the group consisting of hydroxy, =O, halogen, lower alkyl, phenyl, lower alkyl substituted by halogen and lower alkoxy; n, m, o, p, q, r, s and t are each independently 1 or 2; x is 0, 1 or 2; and y is 1 or 2; or a pharmaceutically acceptable salt thereof.

In certain embodiments, the pharmaceutical composition further comprises a pharmaceutically acceptable carrier.

In certain embodiments, the subject is a subject in need thereof. In certain embodiments, the GlyT 1 inhibitor, or pharmaceutically acceptable salt thereof, or prodrug of the GlyT 1 inhibitor or its pharmaceutically acceptable salt, is administered in a therapeutically effective amount.

Brief Description of the Drawings

The file of this patent contains at least one drawing/photograph executed in color. Copies of this patent with color drawing(s)/photograph(s) will be provided by the Office upon request and payment of the necessary fee.

Figures 1A-G show the effect of bitopertin in an erythropoietin (EPO) induced erythrocytosis mouse model of polycythemia vera. Figure 1A shows a schematic image of the experimental strategy used to assess the potential effects of a GlyT1 inhibitor, bitopertin, in a mouse model of polycythemia vera. Various parameters measured using the experimental strategy described in Figure 1A are as follows: body weight changes (Figure IB), drug level in plasma 6 hours after the last dose of GlyT1 inhibitor in mice (Figure 1C); spleen index (Figure ID); change in hematocrit levels (Figure IE); change in red blood cell levels (Figure IF); and change in hemoglobin levels (Figure 1G).

Figures 2A-H show the effect of bitopertin in a darbepoietin-alpha (DPO) induced erythrocytosis mouse model of polycythemia vera. Figure 2A shows a schematic image of the experimental strategy used to assess the potential effects of a GlyT1 inhibitor, bitopertin, in a mouse model of polycythemia vera. Various parameters measured using the experimental strategy described in Figure 2 A are as follows: body weight changes (Figure 2B), change in hematocrit levels (Figure 2C); change in red blood cell levels (Figure 2D); change in hemoglobin levels (Figure 2E); reticulocyte-hemoglobin equivalent (RET-He) levels (Figure 2F); mean corpuscular hemoglobin (MCH) levels (Figure 2G); and mean corpuscular volume (MCV) levels (Figure 2H).

Figure 3A and Figure 3B show schematic images of an experimental strategy which can be used to assess the potential effects of a GlyT 1 inhibitor, such as bitopertin, in a mouse model of polycythemia vera. Figure 3A shows a schematic image of an experimental strategy that can be used to prepare a bone marrow transplantation mouse model of polycythemia vera comprising the Jak2-V617F mutation. Figure 3B shows a schematic image of an experimental strategy that can be used to evaluate the effect of GlyT 1 inhibitors, such as bitopertin, in the polycythemia vera mouse model comprising a Jak2-V617F mutation as described in Figure 3A.

Detailed Description of the Application

Unless defined otherwise, all technical and scientific terms have the same meaning as is commonly understood by one of ordinary skill in the art to which the embodiments disclosed belongs.

As used herein, the terms “a” or “an” means that “at least one” or “one or more” unless the context clearly indicates otherwise.

As used herein, the term “about” means that the numerical value is approximate and small variations would not significantly affect the practice of the disclosed embodiments. Where a numerical limitation is used, unless indicated otherwise by the context, “about” means the numerical value can vary by ±10% and remain within the scope of the disclosed embodiments.

The term “acyl” is art-recognized and refers to a group represented by the general formula hydrocarbylC(O)-, preferably alkylC(O)-.

As used herein, the term “acylamino” means an amino group substituted by an acyl group ( e.g ., -O-C(=O)-H or -O-C(=O)-alkyl). An example of an acylamino is -NHC(=O)H or - NHC ( =O )C H ₃ . The term “lower acylamino” refers to an amino group substituted by a lower acyl group (e.g., -O-C(=O)-H or -O-C(=O)-C _1-6 alkyl). An example of a lower acylamino is - NHC(=O)H or -NHC(=O)CH ₃ .

The term “acyloxy” is art-recognized and refers to a group represented by the general formula hydrocarbylC(O)O-, preferably alkylC(O)O-.

As used herein, the term “alkenyl” means a straight or branched alkyl group having one or more double carbon-carbon bonds and 2-20 carbon atoms, including, but not limited to, ethenyl, 1-propenyl, 2-propenyl, 2 -methyl- 1 -propenyl, 1-butenyl, 2-butenyl, and the like. In some embodiments, the alkenyl chain is from 2 to 10 carbon atoms in length, from 2 to 8 carbon atoms in length, from 2 to 6 carbon atoms in length, or from 2 to 4 carbon atoms in length. The terms “alkoxy”, “phenyloxy”, “benzoxy” and “pyrimidinyloxy” refer to an alkyl group, phenyl group, benzyl group, or pyrimidinyl group, respectively, each optionally substituted, that is bonded through an oxygen atom. For example, the term “alkoxy” means a straight or branched -O-alkyl group of 1 to 20 carbon atoms, including, but not limited to, methoxy, ethoxy, n-propoxy, isopropoxy, t-butoxy, and the like. In some embodiments, the alkoxy chain is from 1 to 10 carbon atoms in length, from 1 to 8 carbon atoms in length, from 1 to 6 carbon atoms in length, from 1 to 4 carbon atoms in length, from 2 to 10 carbon atoms in length, from 2 to 8 carbon atoms in length, from 2 to 6 carbon atoms in length, or from 2 to 4 carbon atoms in length.

As used herein, the term “alkyl” means a saturated hydrocarbon group which is straight-chained or branched. An alkyl group can contain from 1 to 20, from 2 to 20, from 1 to 10, from 2 to 10, from 1 to 8, from 2 to 8, from 1 to 6, from 2 to 6, from 1 to 4, from 2 to 4, from 1 to 3, or 2 or 3 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl (Me), ethyl (Et), propyl ( e.g ., n-propyl and isopropyl), butyl (e.g., n-butyl, t-butyl, isobutyl), pentyl (e.g. , n-pentyl, isopentyl, neopentyl), hexyl, isohexyl, heptyl, 4,4-dimethylpentyl, octyl, 2,2,4-trimethylpentyl, nonyl, decyl, undecyl, dodecyl, 2-methyl- 1- propyl, 2-methyl-2-propyl, 2-methyl- 1 -butyl, 3 -methyl- 1 -butyl, 2 -methyl-3 -butyl, 2-methyl- 1 -pentyl, 2,2-dimethyl- 1 -propyl, 3 -methyl- 1 -pentyl, 4-methyl- 1 -pentyl, 2-methyl-2-pentyl, 3- methyl-2-pentyl, 4-methyl-2-pentyl, 2,2-dimethyl- 1 -butyl, 3,3-dimethyl-l -butyl, 2-ethyl- 1- butyl, and the like.

As used herein, the term “alkylamino” means an amino group substituted by an alkyl group having from 1 to 6 carbon atoms. An example of an alkylamino is -NHCH ₂ CH ₃ .

As used herein, the term “alkylene” or “alkylenyl” means a divalent alkyl linking group. An example of an alkylene (or alkylenyl) is methylene or methylenyl (-CH ₂ -).

As used herein, the term “alkylthio” means an -S-alkyl group having from 1 to 6 carbon atoms. An example of an alkylthio group is -SCH ₂ CH ₃ .

As used herein, the term “alkynyl” means a straight or branched alkyl group having one or more triple carbon-carbon bonds and 2-20 carbon atoms, including, but not limited to, acetylene, 1 -propylene, 2-propylene, and the like. In some embodiments, the alkynyl chain is 2 to 10 carbon atoms in length, from 2 to 8 carbon atoms in length, from 2 to 6 carbon atoms in length, or from 2 to 4 carbon atoms in length.

The term “amide”, as used herein, refers to a group wherein each R ³⁰ independently represent a hydrogen or hydrocarbyl group, or two R ³⁰ are taken together with the N atom to which they are attached complete a heterocycle having from 4 to 8 atoms in the ring structure.

As used herein, the term “amidino” means -C(=NH)NH ₂ .

The terms “amine” and “amino” are art-recognized and refer to both unsubstituted and substituted amines and salts thereof, e.g., a moiety that can be represented by wherein each R ³⁰ independently represents a hydrogen or a hydrocarbyl group, or two R ³⁰ are taken together with the N atom to which they are attached complete a heterocycle having from 4 to 8 atoms in the ring structure. As used herein, the term “aminoalkoxy” means an alkoxy group substituted by an amino group. An example of an aminoalkoxy is -OCH ₂ CH ₂ NH ₂ .

As used herein, the term “aminoalkyl” means an alkyl group substituted by an amino group. An example of an aminoalkyl is -CH ₂ CH ₂ NH ₂ .

As used herein, the term “aminosulfonyl” means -S(=O) ₂ NH ₂ . As used herein, the term “aminoalkylthio” means an alkylthio group substituted by an amino group. An example of an aminoalkylthio is -SCH ₂ CH ₂ NH ₂ .

As used herein, the term “amphiphilic” means a three-dimensional structure having discrete hydrophobic and hydrophilic regions. An amphiphilic compound suitably has the presence of both hydrophobic and hydrophilic elements. As used herein, the term “animal” includes, but is not limited to, humans and non- human vertebrates such as wild, domestic, and farm animals.

As used herein, the term “aryl” means a monocyclic, bicyclic, or polycyclic ( e.g ., having 2, 3 or 4 fused rings) aromatic hydrocarbons. In some embodiments, aryl groups have from 6 to 20 carbon atoms or from 6 to 10 carbon atoms. Examples of aryl groups include, but are not limited to, phenyl, naphthyl, anthracenyl, phenanthrenyl, indanyl, indenyl, tetrahydronaphthyl, and the like. Examples of aryl groups include, but are not limited to:

As used herein, the term “arylalkyl” means a C _1-6 alkyl substituted by aryl.

As used herein, the term “arylamino” means an amino group substituted by an aryl group. An example of an arylamino is -NH(phenyl). As used herein, the term “arylene” means an aryl linking group, i.e., an aryl group that links one group to another group in a molecule.

The term “carbamate” is art-recognized and refers to a group wherein R ²⁹ and R ³⁰ independently represent hydrogen or a hydrocarbyl group, such as an alkyl group, or R ²⁹ and R ³⁰ taken together with the intervening atom(s) complete a heterocycle having from 4 to 8 atoms in the ring structure.

As used herein, the term “carbamoyl” means -C(=O)-NH ₂ .

As used herein, the term “carbocycle” means a 5- or 6-membered, saturated or unsaturated cyclic ring, optionally containing O, S, or N atoms as part of the ring. Examples of carbocycles include, but are not limited to, cyclopentyl, cyclohexyl, cyclopenta- 1,3-diene, phenyl, and any of the heterocycles recited above.

The term “carbocyclylalkyl”, as used herein, refers to an alkyl group substituted with a carbocycle group.

The term “carbonate” is art-recognized and refers to a group -OCO ₂ -R ³⁰ , wherein R ³⁰ represents a hydrocarbyl group.

The term “carboxy”, as used herein, refers to a group represented by the formula -CO ₂ H.

As used herein, the term “carrier” means a diluent, adjuvant, or excipient with which a compound is administered. Pharmaceutical carriers can be liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. The pharmaceutical carriers can also be saline, gum acacia, gelatin, starch paste, talc, keratin, colloidal silica, urea, and the like. In addition, auxiliary, stabilizing, thickening, lubricating and coloring agents can be used.

As used herein, the term, “compound” means all stereoisomers, tautomers, and isotopes of the compounds described herein.

As used herein, the terms “comprising” (and any form of comprising, such as “comprise”, “comprises”, and “comprised”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”), or “containing” (and any form of containing, such as “contains” and “contain”), are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

As used herein, the term “contacting” means bringing together of two elements in an in vitro system or an in vivo system. For example, “contacting” a GlyT1 transporter inhibitor with a GlyT 1 transporter with an individual or patient or cell includes the administration of the compound to an individual or patient, such as a human, as well as, for example, introducing a compound into a sample containing a cellular or purified preparation containing the GlyT1 transporter.

As used herein, the term “cyano” means -CN.

As used herein, the term “cycloalkyl” means non-aromatic cyclic hydrocarbons including cyclized alkyl, alkenyl, and alkynyl groups that contain up to 20 ring-forming carbon atoms. Cycloalkyl groups can include mono- or polycyclic ring systems such as fused ring systems, bridged ring systems, and spiro ring systems. In some embodiments, polycyclic ring systems include 2, 3, or 4 fused rings. A cycloalkyl group can contain from 3 to 15, from 3 to 10, from 3 to 8, from 3 to 6, from 4 to 6, from 3 to 5, or 5 or 6 ring-forming carbon atoms. Ring-forming carbon atoms of a cycloalkyl group can be optionally substituted by oxo or sulfido. Examples of cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclopentenyl, cyclohexenyl, cyclohexadienyl, cycloheptatrienyl, norbornyl, norpinyl, norcamyl, adamantyl, and the like. Also included in the definition of cycloalkyl are moieties that have one or more aromatic rings fused (having a bond in common with) to the cycloalkyl ring, for example, benzo or thienyl derivatives of pentane, pentene, hexane, and the like ( e.g ., 2,3-dihydro-lH- indene-l-yl, or lH-inden-2(3H)-one-l-yl).

As used herein, the term “cycloalkylalkyl” means a C _1-6 alkyl substituted by cycloalkyl.

As used herein, the term “dialkylamino” means an amino group substituted by two alkyl groups, each having from 1 to 6 carbon atoms.

As used herein, the term “diazamino” means -N(NH ₂ ) ₂ .

The term “ester”, as used herein, refers to a group -C(O)O R ³⁰ wherein R ³⁰ represents a hydrocarbyl group. The term “ether”, as used herein, refers to a hydrocarbyl group linked through an oxygen to another hydrocarbyl group. Accordingly, an ether substituent of a hydrocarbyl group may be hydrocarbyl-O. Ethers may be either symmetrical or unsymmetrical. Examples of ethers include, but are not limited to, heterocycle-O-heterocycle and aryl-O- heterocycle. Ethers include “alkoxyalkyl” groups, which may be represented by the general formula alkyl-O-alkyl.

As used herein, the term “facially amphiphilic” or “facial amphiphilicity” means compounds with polar (hydrophilic) and nonpolar (hydrophobic) side chains that adopt conformation(s) leading to segregation of polar and nonpolar side chains to opposite faces or separate regions of the structure or molecule.

As used herein, the term “glycine transporter” or “GlyT” refers to membrane protein that facilitates the transport of glycine across the plasma membrane of a cell. Non-limiting examples of glycine transports include glycine transporter 1 (GlyT1) and glycine transporter 2 (GlyT2).

As used herein, the term “GlyT1” or “GlyT1 transporter” means sodium- and chloride-dependent glycine transporter 1 , also known as glycine transporter 1 , is a protein that in humans is encoded by the SLC6A9 gene (Kim KM, Kingsmore SF, Han H, Yang- Feng TL, Godinot N, Seldin MF, Caron MG, Giros B (Jun 1994). "Cloning of the human glycine transporter type 1 : molecular and pharmacological characterization of novel isoform variants and chromosomal localization of the gene in the human and mouse genomes". Mol Pharmacol. 45 (4): 608-17; Jones EM, Femald A, Bell GI, Le Beau MM (Nov 1995). "Assignment of SLC6A9 to human chromosome band lp33 by in situ hybridization". Cytogenet C ₆ ll Genet. 71 (3): 211), which is hereby incorporated by reference in its entirety.

As used herein, the term “GlyT2” or “GlyT2 transporter” means sodium- and chloride-dependent glycine transporter 2, also known as glycine transporter 2, is a protein that in humans is encoded by the SLC6A5 gene (Morrow JA, Collie IT, Dunbar DR, Walker GB, Shahid M, Hill DR (November 1998). "Molecular cloning and functional expression of the human glycine transporter GlyT2 and chromosomal localisation of the gene in the human genome". FEBS Lett. 439 (3): 334-40), which is hereby incorporated by reference in its entirety. As used herein, the term “GlyT 1 inhibitor” means a compound that inhibits or blocks the activity of GlyT 1 transporter including compounds inhibiting the activity of any isoform of GlyT1. Non- limiting examples of GlyT1 inhibitors are provided herein. In some embodiments, the GlyT 1 inhibitor is a specific GlyT 1 inhibitor, which means that the inhibitor has an inhibitor activity that is greater for GlyT1 as compared to GlyT2. In some embodiments, the inhibitor inhibits GlyT 1 as compared to GlyT2 with at least, or about, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%,. 98%, 99% selectivity. In some embodiments, the GlyT 1 inhibitor inhibits GlyT 1 but does not inhibit or significantly inhibit the activity of GlyT2. A GlyT1 inhibitor that does not significantly inhibit the activity of GlyT2 if it inhibits the activity of GlyT2 less than 5%, 4%, 3%, 2%, or 1%. The selectivity of GlyT 1 inhibitor is determined based on the known assays in the art such as the assays described in the published journal article (B. N. Atkinson, S. C. Bell, M. De Vivo, L. R. Kowalski, S. M. Lechner, V. I. Ognyanov, C.-S. Tham, C. Tsai, J. Jia, D. Ashton and M.

A. Klitenick, ALX 5407: A Potent, Selective Inhibitor of the hGlyT1 Glycine Transporter, Molecular Pharmacology December 2001, 60 (6) 1414-1420), which is incorporated by its entirety.

As used herein, the term “GlyT2 inhibitor” means a compound that inhibits or blocks the activity of GlyT2 transporter including compounds inhibiting the activity of any isoform of GlyT2. In some embodiments, the GlyT2 inhibitor is a non-specific inhibitor, which means that it can also inhibit or block the activity of GlyT 1. In some embodiments, the GlyT2 inhibitor is a specific GlyT2 inhibitor, which means that the inhibitor has an inhibitor activity that is greater for GlyT2 as compared to GlyT 1. In some embodiments, the inhibitor inhibits GlyT2 as compared to GlyT1 with at least, or about, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%,. 98%, 99% selectivity. In some embodiments, the GlyT2 inhibitor inhibits GlyT2 activity but does not inhibit or significantly inhibit the activity of GlyT1. A GlyT2 inhibitor that does not significantly inhibit the activity of GlyT1 if it inhibits the activity of GlyT1 less than 5%, 4%, 3%, 2%, or 1%. The selectivity of GlyT2 inhibitor is determined based on the known assays in the art such as the assays based described in the published journal article (B. N. Atkinson, S. C. Bell, M. De Vivo, L. R. Kowalski, S. M. Lechner, V. I. Ognyanov, C.-S. Tham, C. Tsai, J. Jia, D. Ashton and M. A. Klitenick, ALX 5407: A Potent, Selective Inhibitor of the hGlyT1 Glycine Transporter, Molecular Pharmacology December 2001, 60 (6) 1414-1420), which is incorporated by its entirety.

As used herein, the term “guanidino” means -NH(= NH)NH ₂ .

As used herein, the term “halo” means halogen groups including, but not limited to fluoro, chloro, bromo, and iodo.

As used herein, the term “haloalkoxy” means an -O-haloalkyl group. An example of an haloalkoxy group is OCF ₃ .

As used herein, the term “haloalkyl” means a C _l- ealkyl group having one or more halogen substituents. Examples of haloalkyl groups include, but are not limited to, CF ₃ , C ₂ F ₅ , CH ₂ F, CHF ₂ , CCI ₃ , CHCl ₂ , CH ₂ CF ₃ , and the like.

As used herein, the term “heteroaryl” means an aromatic heterocycle having up to 20 ring-forming atoms (e.g., C) and having at least one heteroatom ring member (ring-forming atom) such as sulfur, oxygen, or nitrogen. In some embodiments, the heteroaryl group has at least one or more heteroatom ring-forming atoms, each of which is, independently, sulfur, oxygen, or nitrogen. In some embodiments, the heteroaryl group has from 3 to 20 ring- forming atoms, from 3 to 10 ring-forming atoms, from 3 to 6 ring- forming atoms, or from 3 to 5 ring-forming atoms. In some embodiments, the heteroaryl group contains 2 to 14 carbon atoms, from 2 to 7 carbon atoms, or 5 or 6 carbon atoms. In some embodiments, the heteroaryl group has 1 to 4 heteroatoms, 1 to 3 heteroatoms, or 1 or 2 heteroatoms.

Heteroaryl groups include monocyclic and polycyclic (e.g., having 2, 3 or 4 fused rings) systems. Examples of heteroaryl groups include, but are not limited to, pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, furyl, quinolyl, isoquinolyl, thienyl, imidazolyl, thiazolyl, indolyl (such as indol-3-yl), pyrroyl, oxazolyl, benzofuryl, benzothienyl, benzthiazolyl, isoxazolyl, pyrazolyl, triazolyl, tetrazolyl, indazolyl, 1,2,4-thiadiazolyl, isothiazolyl, benzothienyl, purinyl, carbazolyl, benzimidazolyl, indolinyl, pyranyl, oxadiazolyl, isoxazolyl, triazolyl, thianthrenyl, pyrazolyl, indolizinyl, isoindolyl, isobenzofuranyl, benzoxazolyl, xanthenyl, 2H-pyrrolyl, pyrrolyl, 3H-indolyl, 4H-quinolizinyl, phthalazinyl, naphthyridinyl, quinazolinyl, phenanthridinyl, acridinyl, perimidinyl, phenanthrolinyl, phenazinyl, isothiazolyl, phenothiazinyl, isoxazolyl, furanyl, phenoxazinyl groups, and the like. Suitable heteroaryl groups include 1,2,3-triazole, 1,2,4-triazole, 5 -amino- 1,2, 4-triazole, imidazole, oxazole, isoxazole, 1,2,3-oxadiazole,

1,2,4-oxadiazole, 3-amino- 1, 2, 4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, pyridine, and 2-aminopyridine.

As used herein, the term “heteroarylalkyl” means a C _1-6 alkyl group substituted by a heteroaryl group.

As used herein, the term “heteroarylamino” means an amino group substituted by a heteroaryl group. An example of a heteroarylamino is -NH-(2-pyridyl).

As used herein, the term “heteroarylene” means a heteroaryl linking group, i.e., a heteroaryl group that links one group to another group in a molecule.

The term “heteroatom” as used herein means an atom of any element other than carbon or hydrogen. Exemplary heteroatoms are nitrogen, oxygen, and sulfur.

As used herein, the term “heterocycle” or “heterocyclic ring” means a 5- to 7- membered mono- or bicyclic or 7- to 10-membered bicyclic heterocyclic ring system any ring of which may be saturated or unsaturated, and which consists of carbon atoms and from one to three heteroatoms chosen from N, O and S, and wherein the N and S heteroatoms may optionally be oxidized, and the N heteroatom may optionally be quatemized, and including any bicyclic group in which any of the above-defined heterocyclic rings is fused to a benzene ring. Particularly useful are rings containing one oxygen or sulfur, one to three nitrogen atoms, or one oxygen or sulfur combined with one or two nitrogen atoms. The heterocyclic ring may be attached at any heteroatom or carbon atom which results in the creation of a stable structure. Examples of heterocyclic groups include, but are not limited to, piperidinyl, piperazinyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolodinyl, 2-oxoazepinyl, azepinyl, pyrrolyl, 4-piperidonyl, pyrrolidinyl, pyrazolyl, pyrazolidinyl, imidazolyl, imidazolinyl, imidazolidinyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, oxazolyl, oxazolidinyl, isoxazolyl, isoxazolidinyl, morpholinyl, thiazolyl, thiazolidinyl, isothiazolyl, quinuclidinyl, isothiazolidinyl, indolyl, quinolinyl, isoquinolinyl, benzimidazolyl, thiadiazoyl, benzopyranyl, benzothiazolyl, benzoxazolyl, furyl, tetrahydrofuryl, tetrahydropyranyl, thienyl, benzothienyl, thiamorpholinyl, thiamorpholinyl sulfoxide, thiamorpholinyl sulfone, and oxadiazolyl. Morpholino is the same as morpholinyl. As used herein, the term “heterocycloalkyl” means non-aromatic heterocycles having up to 20 ring-forming atoms including cyclized alkyl, alkenyl, and alkynyl groups, where one or more of the ring-forming carbon atoms is replaced by a heteroatom such as an O, N, or S atom. Hetercycloalkyl groups can be mono or polycyclic (e.g., fused, bridged, or spiro systems). In some embodiments, the heterocycloalkyl group has from 1 to 20 carbon atoms, or from 3 to 20 carbon atoms. In some embodiments, the heterocycloalkyl group contains 3 to 14 ring-forming atoms, 3 to 7 ring- forming atoms, or 5 or 6 ring-forming atoms. In some embodiments, the heterocycloalkyl group has 1 to 4 heteroatoms, 1 to 3 heteroatoms, or 1 or 2 heteroatoms. In some embodiments, the heterocycloalkyl group contains 0 to 3 double bonds. In some embodiments, the heterocycloalkyl group contains 0 to 2 triple bonds. Examples of heterocycloalkyl groups include, but are not limited to, morpholino, thiomorpholino, piperazinyl, tetrahydrofuranyl, tetrahydrothienyl, 2,3-dihydrobenzofuryl, 1,3-benzodioxole, benzo-l,4-dioxane, piperidinyl, pyrrolidinyl, isoxazolidinyl, oxazolidinyl, isothiazolidinyl, pyrazolidinyl, thiazolidinyl, imidazolidinyl, pyrrolidin-2-one-3-yl, and the like. In addition, ring-forming carbon atoms and heteroatoms of a heterocycloalkyl group can be optionally substituted by oxo or sulfido. For example, a ring-forming S atom can be substituted by 1 or 2 oxo (form a S(O) or S(O) ₂ ). For another example, a ring-forming C atom can be substituted by oxo (form carbonyl). Also included in the definition of heterocycloalkyl are moieties that have one or more aromatic rings fused (having a bond in common with) to the nonaromatic heterocyclic ring including, but not limited to, pyridinyl, thiophenyl, phthalimidyl, naphthalimidyl, and benzo derivatives of heterocycles such as indolene, isoindolene, 4,5,6,7-tetrahydrothieno[2,3-c]pyridine-5-yl, 5,6-dihydrothieno[2,3-c]pyridin- 7(4H)-one-5-yl, isoindolin-l-one-3-yl, and 3,4-dihydroisoquinolin-l(2H)-one-3yl groups. Ring- forming carbon atoms and heteroatoms of the heterocycloalkyl group can be optionally substituted by oxo or sulfido.

As used herein, the term “heterocycloalkylalkyl” refers to a C _1-6 alkyl substituted by heterocycloalkyl.

As used herein, the term “hydroxy” or “hydroxyl” means an -OH group.

As used herein, the term “hydroxyalkyl” or “hydroxylalkyl” means an alkyl group substituted by a hydroxyl group. Examples of a hydroxylalkyl include, but are not limited to,

-CH ₂ OH and -CH ₂ CH ₂ OH. As used herein, the term “individual” or “patient,” used interchangeably, means any animal, including mammals, such as mice, rats, other rodents, rabbits, dogs, cats, swine, cattle, sheep, horses, or primates, such as humans.

As used herein, the phrase “inhibiting activity,” such as enzymatic or transporter activity means reducing by any measurable amount the activity of an enzyme or transporter, such as the GlyT1 transporter.

As used herein, the phrase “in need thereof’ means that the animal or mammal has been identified as having a need for the particular method or treatment. In some embodiments, the identification can be by any means of diagnosis. In any of the methods and treatments described herein, the animal or mammal can be in need thereof. In some embodiments, the animal or mammal is in an environment or will be traveling to an environment in which a particular disease, disorder, or condition is prevalent.

As used herein, the phrase “in situ gellable” means embracing not only liquids of low viscosity that form gels upon contact with the eye or with lacrimal fluid in the exterior of the eye, but also more viscous liquids such as semi-fluid and thixotropic gels that exhibit substantially increased viscosity or gel stiffness upon administration to the eye.

As used herein, the phrase “integer from X to Y” means any integer that includes the endpoints. For example, the phrase “integer from X to Y” means 1, 2, 3, 4, or 5.

The term “lower” when used in conjunction with a chemical moiety, such as, acyl, acyloxy, alkyl, alkenyl, alkynyl, or alkoxy is meant to include groups where there are ten or fewer non-hydrogen atoms in the substituent, preferably six or fewer. A “lower alkyl”, for example, refers to an alkyl group that contains ten or fewer carbon atoms, preferably six or fewer. In certain embodiments, acyl, acyloxy, alkyl, alkenyl, alkynyl, or alkoxy substituents defined herein are respectively lower acyl, lower acyloxy, lower alkyl, lower alkenyl, lower alkynyl, or lower alkoxy, whether they appear alone or in combination with other substituents, such as in the recitations hydroxyalkyl and aralkyl (in which case, for example, the atoms within the aryl group are not counted when counting the carbon atoms in the alkyl substituent). As used herein, the term “mammal” means a rodent (i.e., a mouse, a rat, or a guinea pig), a monkey, a cat, a dog, a cow, a horse, a pig, or a human. In some embodiments, the mammal is a human.

As used herein, the term “N-alkyl” refers to a alkyl chain that is substituted with an amine group. Non-limiting examples, include, but are not limited to and the like. The alkyl chain can be linear, branched, cyclic, or any combination thereof. In some embodiments, the alkyl comprises 1-10, 1-9, 1-8, 1-7, 1-6, 1-5, 1-4, 1-3, or 1-2 carbons.

As used herein, the term “nitro” means -NO2.

As used herein, the term “n-membered”, where n is an integer, typically describes the number of ring-forming atoms in a moiety, where the number of ring-forming atoms is n. For example, pyridine is an example of a 6-membered heteroaryl ring and thiophene is an example of a 5-membered heteroaryl ring.

As used herein, the phrase “ophthalmically acceptable” means having no persistent detrimental effect on the treated eye or the functioning thereof, or on the general health of the subject being treated. However, it will be recognized that transient effects such as minor irritation or a “stinging” sensation are common with topical ophthalmic administration of drugs and the existence of such transient effects is not inconsistent with the composition, formulation, or ingredient ( e.g ., excipient) in question being “ophthalmically acceptable” as herein defined.

As used herein, the phrase “optionally substituted” means that substitution is optional and therefore includes both unsubstituted and substituted atoms and moieties. A “substituted” atom or moiety indicates that any hydrogen on the designated atom or moiety can be replaced with a selection from the indicated substituent groups, provided that the normal valency of the designated atom or moiety is not exceeded, and that the substitution results in a stable compound. For example, if a methyl group is optionally substituted, then 3 hydrogen atoms on the carbon atom can be replaced with substituent groups.

As used herein, the phrase “pharmaceutically acceptable” means those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with tissues of humans and animals. In some embodiments, “pharmaceutically acceptable” means approved by a regulatory agency of the Federal or a state government or listed in the U.S. Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly in humans.

A “pharmaceutically acceptable salt” is intended to mean a salt of a free acid or base of a compound represented herein that is non-toxic, biologically tolerable, or otherwise biologically suitable for administration to the subject. See, generally, S.M. Berge, et al, “Pharmaceutical Salts,” J. Pharm. Sci., 1977, 66, 1-19. Preferred pharmaceutically acceptable salts are those that are pharmacologically effective and suitable for contact with the tissues of subjects without undue toxicity, irritation, or allergic response. A compound described herein may possess a sufficiently acidic group, a sufficiently basic group, both types of functional groups, or more than one of each type, and accordingly react with a number of inorganic or organic bases, and inorganic and organic acids, to form a pharmaceutically acceptable salt.

For a compound described herein that contains a basic group, such as an amine, a pharmaceutically acceptable salt may be prepared by any suitable method available in the art, for example, treatment of the free base with an inorganic acid, such as hydrochloric acid, hydrobromic acid, sulfuric acid, sulfamic acid, nitric acid, boric acid, phosphoric acid, and the like, or with an organic acid, such as acetic acid, phenylacetic acid, propionic acid, stearic acid, lactic acid, ascorbic acid, maleic acid, hydroxymaleic acid, isethionic acid, succinic acid, valeric acid, fumaric acid, malonic acid, pyruvic acid, oxalic acid, glycolic acid, salicylic acid, oleic acid, palmitic acid, lauric acid, a pyranosidyl acid, such as glucuronic acid or galacturonic acid, an alpha-hydroxy acid, such as mandelic acid, citric acid, or tartaric acid, an amino acid, such as aspartic acid or glutamic acid, an aromatic acid, such as benzoic acid, 2-acetoxybenzoic acid, naphthoic acid, or cinnamic acid, a sulfonic acid, such as laurylsulfonic acid, p-toluenesulfonic acid, methanesulfonic acid, or ethanesulfonic acid, or any compatible mixture of acids such as those given as examples herein, and any other acid and mixture thereof that are regarded as equivalents or acceptable substitutes in light of the ordinary level of skill in this technology.

For a compound described herein that contains an acidic group, such as a carboxylic acid group, base addition salts can be prepared by any suitable method available in the art, for example, treatment of such compound with a sufficient amount of the desired the desired base, either neat or in a suitable inert solvent. Examples of pharmaceutically acceptable base addition salts include, but are not limited to, lithium, sodium, potassium, calcium, ammonium, zinc, or magnesium salt, or other metal salts; organic amino salts, such as, alkyl, dialkyl, trialkyl, or tetra-alkyl ammonium salts.

Other examples of pharmaceutically acceptable salts include, but are not limited to, camsylate, sulfates, pyrosulfates, bisulfates, sulfites, bisulfites, phosphates, monohydrogen- phosphates, dihydrogenphosphates, metaphosphates, pyrophosphates, chlorides, bromides, iodides, acetates, propionates, decanoates, caprylates, acrylates, formates, isobutyrates, caproates, heptanoates, propiolates, oxalates, malonates, succinates, suberates, sebacates, fumarates, maleates, butyne-l,4-dioates, hexyne-l,6-dioates, benzoates, chlorobenzoates, methylbenzoates, dinitrobenzoates, hydroxybenzoates, methoxybenzoates, phthalates, sulfonates, methylsulfonates, propylsulfonates, besylates, xylenesulfonates, naphthalene- 1 - sulfonates, naphthalene-2-sulfonates, phenylacetates, phenylpropionates, phenylbutyrates, citrates, lactates, g-hydroxybutyrates, glycolates, tartrates, and mandelates. Lists of other suitable pharmaceutically acceptable salts are found in Remington's Pharmaceutical Sciences, 17th Edition, Mack Publishing Company, Easton, Pa., 1985.

The neutral forms of the compounds are preferably regenerated by contacting the salt with a base or acid and isolating the parent compound in the conventional manner. The parent form of the compound differs from the various salt forms in certain physical properties, such as solubility in polar solvents, but otherwise the salts are equivalent to the parent form of the compound for the purposes of the present application.

As used herein, the term “phenyl” means -C ₆ H ₅ . A phenyl group cn be unsubstituted or substituted with one, two, or three suitable substituents.

The terms “polycyclyl”, “polycycle”, and “polycyclic” refer to two or more rings (e.g., cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and/or heterocyclyls) in which two or more atoms are common to two adjoining rings, e.g., the rings are “fused rings”. Each of the rings of the polycycle can be substituted or unsubstituted. In certain embodiments, each ring of the polycycle contains from 3 to 10 atoms in the ring, preferably from 5 to 7.

As used herein, the term “prodrug” means a derivative of a known direct acting drug, which derivative has enhanced delivery characteristics and therapeutic value as compared to the drug, and is transformed into the active drug by an enzymatic or chemical process. A common method for making a prodrug is to include one or more selected moieties which are hydrolyzed under physiologic conditions to yield the desired molecule. In certain embodiments, the prodrug is converted by an enzymatic activity of the host animal. For example, a prodrug with a nitro group on an aromatic ring could be reduced by reductase to generate the desired amino group of the corresponding active compound in vivo. In another example, functional groups such as a hydroxyl, carbonate, or carboxylic acid in the parent compound are presented as an ester, which could be cleaved by esterases. Additionally, amine groups in the parent compounds are presented in, but not limited to, carbamate, N- alkylated or N-acylated forms (Simplicio et al, “Prodrugs for Amines,” Molecules, (2008), 13:519-547). In certain embodiments, some or all of the compounds of described herein in a formulation represented above can be replaced with the corresponding suitable prodrug.

As used herein, the term “purified” means that when isolated, the isolate contains at least 90%, at least 95%, at least 98%, or at least 99% of a compound described herein by weight of the isolate.

As used herein, the phrase “quaternary ammonium salts” means derivatives of the disclosed compounds with one or more tertiary amine moieties wherein at least one of the tertiary amine moieties in the parent compound is modified by converting the tertiary amine moiety to a quaternary ammonium cation via alkylation (and the cations are balanced by anions such as Cl-, CH ₃ COO-, and CF ₃ COO-), for example methylation or ethylation.

As used herein, the term “semicarbazone” means =NNHC(=O)NH ₂ .

As used herein, the phrase “solubilizing agent” means agents that result in formation of a micellar solution or a true solution of the drug.

As used herein, the term “solution/suspension” means a liquid composition wherein a first portion of the active agent is present in solution and a second portion of the active agent is present in particulate form, in suspension in a liquid matrix.

As used herein, the phrase “substantially isolated” means a compound that is at least partially or substantially separated from the environment in which it is formed or detected.

The term “substituted” refers to moieties having substituents replacing a hydrogen on one or more carbons of the backbone. It will be understood that “substitution” or “substituted with” includes the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound, e.g. , which does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc. As used herein, the term “substituted” is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and non-aromatic substituents of organic compounds. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this application, the heteroatoms such as nitrogen may have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valences of the heteroatoms.

Substituents can include any substituents described herein, for example, a halogen, a hydroxyl, a carbonyl (such as a carboxyl, an alkoxycarbonyl, a formyl, or an acyl), a thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), an alkoxyl, a phosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl, an aralkyl, or an aromatic or heteroaromatic moiety. It will be understood by those skilled in the art that substituents can themselves be substituted, if appropriate. Unless specifically stated as “unsubstituted,” references to chemical moieties herein are understood to include substituted variants. For example, reference to an “aryl” group or moiety implicitly includes both substituted and unsubstituted variants.

The term “sulfate” is art-recognized and refers to the group -OSO3H, or a pharmaceutically acceptable salt thereof.

The term “sulfonamide” is art-recognized and refers to the group represented by the general formulae wherein R ²⁹ and R ³⁰ independently represents hydrogen or hydrocarbyl, such as alkyl, or R ²⁹ and R ³⁰ taken together with the intervening atom(s) complete a heterocycle having from 4 to 8 atoms in the ring structure. The term “sulfoxide” is art-recognized and refers to the group -S(O)-R ³⁰ , wherein R ³⁰ represents a hydrocarbyl.

The term “sulfonate” is art-recognized and refers to the group SO ₃ H, or a pharmaceutically acceptable salt thereof.

The term “sulfone” is art-recognized and refers to the group -S(O) ₂ -R ³⁰ , wherein R ³⁰ represents a hydrocarbyl.

As used herein, the phrase “therapeutically effective amount” means the amount of active compound or pharmaceutical agent that elicits the biological or medicinal response that is being sought in a tissue, system, animal, individual or human by a researcher, veterinarian, medical doctor or other clinician. The therapeutic effect is dependent upon the disorder being treated or the biological effect desired. As such, the therapeutic effect can be a decrease in the severity of symptoms associated with the disorder and/or inhibition (partial or complete) of progression of the disorder, or improved treatment, healing, prevention or elimination of a disorder, or side-effects. The amount needed to elicit the therapeutic response can be determined based on the age, health, size and sex of the subject. Optimal amounts can also be determined based on monitoring of the subject’s response to treatment.

The term “thioalkyl”, as used herein, refers to an alkyl group substituted with a thiol group.

The term “thioester”, as used herein, refers to a group -C(O)SR ³⁰ or -SC(O)R ³⁰ wherein R ³⁰ represents a hydrocarbyl.

The term “thioether”, as used herein, is equivalent to an ether, wherein the oxygen is replaced with a sulfur.

As used herein, the terms “treat,” “treated,” or “treating” mean both therapeutic treatment and prophylactic measures wherein the object is to slow down (lessen) an undesired physiological condition, disorder or disease, or obtain beneficial or desired clinical results. Beneficial or desired clinical results include, but are not limited to, alleviation of symptoms; diminishment of extent of condition, disorder or disease; stabilized ( i.e ., not worsening) state of condition, disorder or disease; delay in onset or slowing of condition, disorder or disease progression; amelioration of the condition, disorder or disease state or remission (whether partial or total), whether detectable or undetectable; an amelioration of at least one measurable physical parameter, not necessarily discernible by the patient; or enhancement or improvement of condition, disorder or disease. Treatment includes eliciting a clinically significant response without excessive levels of side effects. Treatment also includes prolonging survival as compared to expected survival if not receiving treatment. Thus, “treatment of polycythemia” or “treating polycythemia” means an activity that alleviates or ameliorates any of the primary phenomena or secondary symptoms associated with the polycythemia or other conditions described herein.

The term “urea” is art-recognized and may be represented by the general formula wherein R ²⁹ and R ³⁰ independently represent hydrogen or a hydrocarbyl, such as alkyl, or either occurrence of R ²⁹ taken together with R ³⁰ and the intervening atom(s) complete a heterocycle having from 4 to 8 atoms in the ring structure.

At various places in the present specification, substituents of compounds may be disclosed in groups or in ranges. It is specifically intended that embodiments include each and every individual subcombination of the members of such groups and ranges. For example, the term “C _1-6 alkyl” is specifically intended to individually disclose methyl, ethyl, propyl, C ₄ alkyl, C ₈ alkyl, and C ₆ alkyl.

For compounds in which a variable appears more than once, each variable can be a different moiety selected from the Markush group defining the variable. For example, where a structure is described having two R groups that are simultaneously present on the same compound, the two R groups can represent different moieties selected from the Markush groups defined for R. In another example, when an optionally multiple substituent is designated in the form, for example, , then it is understood that substituent R can occur s number of times on the ring, and R can be a different moiety at each occurrence. In the above example, where the variable T ¹ is defined to include hydrogens, such as when T ¹ is CH ₂ , NH, etc., any IT can be replaced with a substituent. It is further appreciated that certain features described herein, which are, for clarity, described in the context of separate embodiments, can also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, can also be provided separately or in any suitable subcombination.

It is understood that the present embodiments encompasses the use, where applicable, of stereoisomers, diastereomers and optical stereoisomers of the compounds, as well as mixtures thereof. Additionally, it is understood that stereoisomers, diastereomers, and optical stereoisomers of the compounds, and mixtures thereof, are within the scope of the embodiments. By way of non-limiting example, the mixture may be a racemate or the mixture may comprise unequal proportions of one particular stereoisomer over the other. Additionally, the compounds can be provided as a substantially pure stereoisomers, diastereomers and optical stereoisomers (such as epimers).

The compounds described herein can be asymmetric ( e.g ., having one or more stereocenters). All stereoisomers, such as enantiomers and diastereomers, are intended to be included within the scope of the embodiments unless otherwise indicated. Compounds that contain asymmetrically substituted carbon atoms can be isolated in optically active or racemic forms. Methods of preparation of optically active forms from optically active starting materials are known in the art, such as by resolution of racemic mixtures or by stereoselective synthesis. Many geometric isomers of olefins, C=N double bonds, and the like can also be present in the compounds described herein, and all such stable isomers are provided herein. Cis and trans geometric isomers of the compounds are also included within the present embodiments and can be isolated as a mixture of isomers or as separated isomeric forms. Where a compound capable of stereoisomerism or geometric isomerism is designated in its structure or name without reference to specific R/S or cis/trans configurations, it is intended that all such isomers are contemplated.

In some embodiments, the composition comprises a compound, or a pharmaceutically acceptable salt, solvate or prodrug thereof, that is at least 90%, at least 95%, at least 98%, or at least 99%, or 100% enantiomeric pure, which means that the ratio of one enantiomer to the other in the composition is at least 90:1 at least 95:1, at least 98:1, or at least 99: 1, or is completely in the form of one enantiomer over the other. In certain embodiments, the compound enriched in one enantiomer is substantially free of the other enantiomer, wherein substantially free means that the substance in question makes up less than 10%, or less than 5%, or less than 4%, or less than 3%, or less than 2%, or less than 1% as compared to the amount of the other enantiomer, e.g., in the composition or compound mixture. For example, if a composition or compound mixture contains 98 grams of a first enantiomer and 2 grams of a second enantiomer, it would be said to contain 98 mol percent of the first enantiomer and only 2% of the second enantiomer.

In certain embodiments, the compound enriched in one enantiomer is substantially free of the other enantiomer, wherein substantially free means that the substance in question makes up less than 10%, or less than 5%, or less than 4%, or less than 3%, or less than 2%, or less than 1% as compared to the amount of the other enantiomer, e.g., in the composition or compound mixture. For example, if a composition or compound mixture contains 98 grams of a first enantiomer and 2 grams of a second enantiomer, it would be said to contain 98 mol percent of the first enantiomer and only 2% of the second enantiomer.

Resolution of racemic mixtures of compounds can be carried out by any of numerous methods known in the art, including, for example, chiral HPLC, fractional recrystallization using a chiral resolving acid which is an optically active, salt-forming organic acid. Suitable resolving agents for fractional recrystallization methods include, but are not limited to, optically active acids, such as the D and L forms of tartaric acid, diacetyltartaric acid, dibenzoyltartaric acid, mandelic acid, malic acid, lactic acid, and the various optically active camphorsulfonic acids such as β-camphorsulfonic acid. Other resolving agents suitable for fractional crystallization methods include, but are not limited to, stereoisomerically pure forms of α-methylbenzylamine (e.g., S and R forms, or diastereomerically pure forms), 2- phenylglycinol, norephedrine, ephedrine, N-methylephedrine, cyclohexylethylamine, 1,2- diaminocyclohexane, and the like. Resolution of racemic mixtures can also be carried out by elution on a column packed with an optically active resolving agent (e.g. , dinitrobenzoylphenylglycine). Suitable elution solvent compositions can be determined by one skilled in the art.

Compounds may also include tautomeric forms. Tautomeric forms result from the swapping of a single bond with an adjacent double bond together with the concomitant migration of a proton. Tautomeric forms include prototropic tautomers which are isomeric protonation states having the same empirical formula and total charge. Examples of prototropic tautomers include, but are not limited to, ketone-enol pairs, amide-imidic acid pairs, lactam-lactim pairs, amide-imidic acid pairs, enamine-imine pairs, and annular forms where a proton can occupy two or more positions of a heterocyclic system including, but not limited to, 1H- and 3H-imidazole, 1H-, 2H- and 4H- 1,2, 4-triazole, 1H- and 2H- isoindole, and 1H- and 2H-pyrazole. Tautomeric forms can be in equilibrium or sterically locked into one form by appropriate substitution.

Glycine transporter inhibitors, such as GlyT 1 inhibitors, including their pharmaceutically acceptable salts ( e.g ., the GlyT1 inhibitors as disclosed herein) can also exist as hydrates and solvates, as well as anhydrous and non-solvated forms. A “hydrate” is a compound that exists in a composition with water molecules. The composition can include water in stoichiometric quantities, such as a monohydrate or a dihydrate, or can include water in random amounts. A “solvate” is a similar composition except that a solvent other that water, such as with methanol, ethanol, dimethylformamide, diethyl ether and the like replaces the water. For example, methanol or ethanol can form an “alcoholate,"” which can again be stoichiometic or non-stoichiometric. Mixtures of such solvates or hydrates can also be prepared. The source of such solvate or hydrate can be from the solvent of crystallization, inherent in the solvent of preparation or crystallization, or adventitious to such solvent.

The compounds of the application, including their pharmaceutically acceptable salts and prodrugs, can exist as various polymorphs, pseudo-polymorphs, or in amorphous state. The term “polymorph”, as used herein, refers to different crystalline forms of the same compound and other solid state molecular forms including pseudo-polymorphs, such as hydrates, solvates, or salts of the same compound. Different crystalline polymorphs have different crystal structures due to a different packing of molecules in the lattice, as a result of changes in temperature, pressure, or variations in the crystallization process. Polymorphs differ from each other in their physical properties, such as x-ray diffraction characteristics, stability, melting points, solubility, or rates of dissolution in certain solvents. Thus crystalline polymorphic forms are important aspects in the development of suitable dosage forms in pharmaceutical industry. Compounds can also include all isotopes of atoms occurring in the intermediates or final compounds. Isotopes include those atoms having the same atomic number but different mass numbers. For example, isotopes of hydrogen include tritium and deuterium.

In some embodiments, the compounds, or salts thereof, are substantially isolated. Partial separation can include, for example, a composition enriched in the compound. Substantial separation can include compositions containing at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 97%, or at least about 99% by weight of the compound, or salt thereof. Methods for isolating compounds and their salts are routine in the art.

Although the disclosed compounds are suitable, other functional groups can be incorporated into the compound with an expectation of similar results. In particular, thioamides and thioesters are anticipated to have very similar properties. The distance between aromatic rings can impact the geometrical pattern of the compound and this distance can be altered by incorporating aliphatic chains of varying length, which can be optionally substituted or can comprise an amino acid, a dicarboxylic acid or a diamine. The distance between and the relative orientation of monomers within the compounds can also be altered by replacing the amide bond with a surrogate having additional atoms. Thus, replacing a carbonyl group with a dicarbonyl alters the distance between the monomers and the propensity of dicarbonyl unit to adopt an anti- arrangement of the two carbonyl moiety and alter the periodicity of the compound. Pyromellitic anhydride represents still another alternative to simple amide linkages which can alter the conformation and physical properties of the compound. Modem methods of solid phase organic chemistry (E. Atherton and R. C. Sheppard, Solid Phase Peptide Synthesis A Practical Approach IRL Press Oxford 1989) now allow the synthesis of homodisperse compounds with molecular weights approaching 5,000 Daltons. Other substitution patterns are equally effective.

The compounds also include derivatives referred to as prodrugs.

Compounds containing an amine function can also form N-oxides. A reference herein to a compound that contains an amine function also includes the N-oxide. Where a compound contains several amine functions, one or more than one nitrogen atom can be oxidized to form an N-oxide. Examples of N-oxides include N-oxides of a tertiary amine or a nitrogen atom of a nitrogen- containing heterocycle. N-Oxides can be formed by treatment of the corresponding amine with an oxidizing agent such as hydrogen peroxide or a per-acid ( e.g ., a peroxycarboxylic acid) (see, Advanced Organic Chemistry, by Jerry March, 4th Edition, Wiley Interscience).

By hereby reserving the right to proviso out or exclude any individual members of any such group, including any sub-ranges or combinations of sub-ranges within the group, that can be claimed according to a range or in any similar manner, less than the full measure of this disclosure can be claimed for any reason. Further, by hereby reserving the right to proviso out or exclude any individual substituents, analogs, compounds, ligands, structures, or groups thereof, or any members of a claimed group, less than the full measure of this disclosure can be claimed for any reason. Throughout this disclosure, various patents, patent applications and publications are referenced. The disclosures of these patents, patent applications and publications in their entireties are incorporated into this disclosure by reference in order to more fully describe the state of the art as known to those skilled therein as of the date of this disclosure. This disclosure will govern in the instance that there is any inconsistency between the patents, patent applications and publications cited and this disclosure.

For convenience, certain terms employed in the specification, examples and claims are collected here. Unless defined otherwise, all technical and scientific terms used in this disclosure have the same meanings as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

Embodiments of various compounds and salts thereof are provided. Where a variable is not specifically recited, the variable can be any option described herein, except as otherwise noted or dictated by context.

In some embodiments, the compound is as described in the appended exemplary, non- limiting claims, or a pharmaceutically acceptable salt, solvate or prodrug thereof.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound of Formula I,

Formula I, wherein:

Ar is unsubstituted or substituted aryl or 6-membered heteroaryl containing one, two or three nitrogen atoms, wherein the substituted aryl and the substituted heteroaryl groups are substituted by one or more substituents selected from the group consisting of hydroxy, halogen, NO2, CN, (C ₁ -C ₆ )-alkyl, (C ₁ -C ₆ )-alkyl substituted by halogen, (C ₁ -C ₆ )-alkyl substituted by hydroxy, (CHl2)n — (C ₁ -C ₆ )-alkoxy, (C ₁ -C ₆ )-alkoxy substituted by halogen, NR ⁷ R ⁸ C(O)R ⁹ , SO2R ¹⁰ , and — C(CH ₃ )=NOR ⁷ , or are substituted by a 5-membered aromatic heterocycle containing 1-4 heteroatoms selected from N and O, which is optionally substituted by (C ₁ -C ₆ )-alkyl;

R ¹ is hydrogen or (C ₁ -C ₆ )-alkyl;

R ² is hydrogen, (C ₁ -C ₆ )-alkyl, (C ₂ -C ₆ )-alkenyl, (C ₁ -C ₆ )-alkyl substituted by halogen, (C ₁ -C ₆ )-alkyl substituted by hydroxy, (CH2)n — (C ₃ -C ₇ )-cycloalkyl optionally substituted by (C ₁ -C ₆ )-alkoxy or by halogen, CH(CH ₃ ) — (C ₃ -C ₇ )-cycloalkyl, (CH ₂ ) _n+1 — C(O) — R ⁹ ,

(CH ₂ ) _n+1 — CN, bicyclo[2.2.1]heptyl, (CH ₂ ) _n+1 — O — (C ₁ -C ₆ )-alkyl, (CH ₂ ) _n -heterocychloalkyl,

(CH ₂ ) _n -aryl or (CH ₂ ) _n -5 or 6-membered heteroaryl containing one, two or three heteroatoms selected from the group consisting of oxygen, sulphur or nitrogen wherein aryl, heterocycloalkyl and heteroaryl are unsubstituted or substituted by one or more substituents selected from the group consisting of hydroxy, halogen, (C ₁ -C ₆ )-alkyl and (C ₁ -C ₆ )-alkoxy;

R ³ , R ⁴ and R ⁶ are each independently hydrogen, hydroxy, halogen, (C ₁ -C ₆ )-alkyl, (C ₁ - C ₆ )-alkoxy or O — (C ₃ -C ₆ )-cycloalkyl;

R ⁵ is NO ₂ , CN, C(O)R ⁹ or SO ₂ R ¹⁰ ;

R ⁷ and R ⁸ are each independently hydrogen or (Cl-C6)-alkyl;

R ⁹ is hydrogen, (C ₁ -C ₆ )-alkyl, (C ₁ -C ₆ )-alkoxy or NR ⁷ R ⁸ ; R ¹⁰ is (C ₁ -C ₆ )-alkyl optionally substituted by halogen, (CH ₂ ) _n — (C ₃ -C ₆ )-cycloalkyl, (CH ₂ ) _n — (C ₃ -C ₆ )-alkoxy, (CH ₂ ) _n -heterocycloalkyl or NR ⁷ R ⁸ ; n is 0, 1, or 2; or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound having a formula of , bitopertin, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound of Formula II, Formula II, wherein:

Ri represents a heteroaryl selected from the group consisting of: imidazolyl, thiazolyl, pyridyl, oxazolyl, pyrazolyl, triazolyl, oxadiazolyl, quinolinyl, isoxazolyl, pyrroloimidazoyl, and thiadiazole, wherein said heteroaryl is optionally substituted by one or more substituents selected from -OH, -NR ₇ R ₈ , halogen, (C ₁ -C ₈ )alkyl, (C ₃ -C ₁₀ )cycloalkyl, (C ₁ -C ₈ )alkoxy, (C ₁ - C ₁₂ )alkoxyalkyl, (C ₁ -C ₈ )hydroxyalkyl, (C ₆ -C ₁₄ )aryl and benzyl; R ₂ , R ₃ and A independently represent H or (C ₁ -C ₈ )alkoxy, wherein said alkyl is optionally substituted by one or more -OH, (C ₁ -C ₈ )alkoxy, -NR ₇ R ₈ or halogen;

Q represents -(CH ₂ ) _n -, where n = 1, 2, 3 or 4 or -(CH ₂ V-O-, where m = 2, 3 or 4;

Z represents (C ₆ -C ₁₄ )aryl, (C ₁ -C ₈ )alkyl or (C ₃ -C ₈ cycloalkyl;

R ₄ and R ₅ each independently represent H, halogen, (C ₁ -C ₈ )alkyl, (C ₆ -C ₁₄ )aryl, (C ₆ - C ₁₄ )aryloxy, (C ₁ -C ₈ )alkoxy, (3-10 membered)heterocycloalkyl or (C ₃ -C ₈ )cycloalkoxy; wherein R ₄ and R ₅ are optionally substituted by one or more -OH, (C ₁ -C ₈ )alkoxy, -NR ₇ R ₈ or halogen;

Y represents -R ₆ , -(CH ₂ )o-R ₆ , -C(R ₆ ) ₃ or -CH(R ₆ ) ₂ , wherein 0 = 1, 2 or 3; R ₆ represents H, (C ₆ -C ₁₄ )aryl, (C ₁ -io)alkyl, (C ₃ -C ₁₀ )cycloalkyl, (C ₅ -C ₁₈ )bicycloalkyl, (C ₅ -C ₁₈ )tri cycloalkyl, (3-10 membered)heterocycloalkyl, (5-10 membered)heteroaryl, - C(=O)NR ₇ R ₈ , or -C(=O)OR ₇ , wherein said R ₆ groups can optionally be substituted with one or more X groups; wherein X = -OH, (C ₁ -C ₈ )alkoxy, -NR ₁₁ R ₁₂ , -SO ₂ R ₁₀ , -C(=O)R ₁₀ , halogen, cyano, (C ₁ - C ₈ )alkyl, (C ₁ -C ₁₀ )alkoxyalkyl, (5-10 membered)heteroaryl, (C ₆ -C ₁₄ )aryl, (C ₆ - C ₁₄ )aryloxy, benzyl, or (Cl-C ₈ )hydroxyalkyl; wherein R ₇ and R ₈ independently represent H, (C ₁ -C ₈ )alkyl, (C ₃ -C8)cycloalkyl, (5-10 membered)heterocycloalkyl, (C ₁ -C ₈ )hydroxyalky, (5-10 membered)heteroaryl or (C ₁ - C ₁₀ )alkoxyalkyl; wherein R ₇ and R ₈ may optionally be substituted by one or more X groups; or R ₇ and R ₈ together with the nitrogen in which they may be attached may form a (3- 10 membered)heterocycloalkyl group optionally substituted by one or more X groups; wherein R ₁₀ represents (C ₁ -C ₈ )alkyl, (C ₃ -C ₈ )cycloalkyl, (3-10 membered)heterocycloalkyl, (C ₁ -C ₈ )hydroxyalky, (5-10 membered)heteroaryl or (C ₁ - C ₁₀ )alkoxy alkyl; wherein R ₁₁ and R ₁₂ independently represent H, (C ₁ -C ₈ )alkyl, (C ₃ -C ₈ )cycloalkyl, (5- 10 membered)heterocycloalkyl, (C ₁ -C ₈ )hydroxyalky, (5-10 membered)heteroaryl or (C ₁ - C ₁₀ )alkoxyalkyl; or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt. In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound having a formula of , or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt. In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound having a formula of

^' , PF-3463275, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound of Formula III,

Formula III, wherein:

Z ¹ is selected from the group consisting of C _1-4 alkyl, C _3-6 CycloaIkVl, C _1-4 alkoxy, C ₁ - ₄ alkylthio, haloC _1-4 alkyl, phenyl, haloC _1-4 alkoxy, halophenyl, C _1-4 alkylsulfoxy, C ₁ - ₄ alkylsulfonyl, bromo and chloro; Z ² is selected from the group consisting of hydrogen, halogen, cyano, C _1-4 alkyl, phenyl, haloC _1-4 alkyl, haloC _1-4 alkoxy, halophenyl, C _1-4 alkoxyC _1-4 alkyl and C _3-6 cycloalkyl;

Z ³ is selected from the group consisting of hydrogen, halogen, C _1-4 alkyl, Cwalkoxy, C _1-4 alkylthio, haloC _1-4 alkyl, haloC _1-4 alkoxy, and C _3-6 Cyeloalkyl;

Z ⁴ is selected from the group consisting of hydrogen, halogen, Cl-3alkyl, haloC _{1- 4} alkyl, C _1-4 alkoxy, C _1-4 alkylthio, phenyl, haloC _1-4 alkoxy, halophenyl, C _1-4 alkoxyC _1-4 alkyl and C _3-6 cycloalkyl;

Z ⁵ is selected from the group consisting of hydrogen, fluoro, chloro, bromo, iodo, hydroxy, C _1-4 alkyl, C _1-4 aIkoxy, C _1-4 alkylthio, phenyl, haloC _1-4 alkyl, haloC _1-4 alkoxy, halophenyl, C _1-4 alkoxyC _1-4 alkyl and C _3-6 cycloalkyl; whereby if more than one of Z ¹ to Z ⁵ is methoxy, then only Z ¹ and Z ⁵ are methoxy R ³ and R ⁴ are independently selected from hydrogen and C _1-4 alkyl, optionally substituted with one or more groups Y; or R ³ and R4 together with the nitrogen atom to which they are attached form a saturated or partially unsaturated A-, 5- 6-or 7-membered carbocyclic ring optionally substituted with a group Y';

Y is selected from the group consisting of C _1-4 alkoxy, hydroxy, haloC _1-4 alkoxy and C _3-5 cycloalkyl;

Y' is selected from the group consisting of C _1-4 alkyl, C _1-4 alkoxy, halogen, hydroxy, haloC _1-4 alkoxy, C _3-5C yeloalkyl and C _5-10 aryl or Y' forms a -CH2- or -CH2-CH2- bridge between two atoms on the A-, 5-, 6- or 7-membered carbocyclic ring;

R ⁵ and R ⁶ are independently C _1-4 alkyl, optionally substituted with one or more groups X; or R ⁵ and R ⁶ together with the carbon atom to which they are attached form a saturated 5- or 6-membered ring carbocyclic optionally substituted with one or more groups X', in the case of R ⁵ and R6 together with the carbon atom to which they are attached forming a 5- membered saturated carbocyclic ring, that ring may optionally further comprising an additional heteroatom group selected from O, N and S(O)m; where m = 0, 1 or 2.

X is selected from the group consisting of halogen, hydroxy, C _1-4 alkoxy, haloC ₁ - ₄ alkyl, haloC _1-4 alkoxy and C _5-10 aryl; and X' is selected from the group consisting of halogen, hydroxy, C _1-4 alkyl, C _1-4 alkoxy, haloC _1-4 alkyl, haloC _1-4 alkoxy and C _5-10 aryl; whereby R ³ , R ⁴ , R ⁵ and R ⁶ are not all simultaneously unsubstituted methyl; with the provisos that when simultaneously Z ¹ is propyloxy, Z ³ is chloro, Z ² =Z ⁴ =Z ⁵ =H, and R ⁵ and R ⁶ are both methyl, then R ³ and R ⁴ together with the nitrogen atom to which they are attached do not form a 2-methylpyrrolidine group; when simultaneously Z ¹ is methyl, Z ³ is methoxy, Z ² =Z4=Z5=H, and R ⁵ and R ⁶ are both methyl, then R ³ and R ⁴ together with the nitrogen atom to which they are attached do not form a pyrrolidine group, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound having a formula of , or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound of Formula IV, Formula IV, wherein:

Z is (CH ₂ ) _n , O, S, SO, SO ₂ or N-R ₅ ; n is 0, 1 or 2;

X represents 1-3 substituents independently selected from hydrogen, halogen, (C _1-6 )alkyioxy, (C _3-6 )cycloalkyloxy, (C _6-12 )aryloxy, (C _6-12 )aryl, thienyl, SR6, SOR6,

SO ₂ R ₆ , NR ₆ R ₆ , NHR ₆ , NH ₂ , NHCOR ₆ , NSO ₂ R ₆ , CN, COOR ₆ and (C _1-4 )alkyl, optionally substituted with halogen, (C _6-12 )aryl, (C _1-6 )alkyloxy or (C _6-12 )aryloxy; or 2 substituents at adjacent positions together represent a fused (C ₈ - ₆ )aryl group, a fused (C ₅ - ₆ )cycloalkyl ring or O-(CH ₂ ) _m -O; m is 1 or 2;

Y represents 1-3 substituents independently selected from hydrogen, halogen, (C ₁ - ₄ )alkyloxy, SR ₆ , NR ₆ R ₆ and (C _1-4 )alkyl, optionally substituted with halogen;

R ₁ is COOR ₇ or CONR ₈ R ₉ ;

R ₂ and R6 are (C _1-4 )alkyl;

R ₃ , R ₄ are R ₅ are independently hydrogen or (C _1-4 )alkyl;

R ₇ , R ₈ and R ₉ are independently hydrogen, (C _1-4 )alkyl, (C _6-12 )aryl or arylalkyl, or a pharmaceutically acceptable salt thereof, or a prodrag of the compound or its pharmaceutically acceptable salt.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound having a formula of -25935, or a pharmaceutically acceptable salt thereof, or a prodrag of the compound or its pharmaceutically acceptable salt.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound of Formula V,

Formula V, wherein: n is an integer from 1 to 3;

R ¹ and R ² are independently selected from hydrogen, alkyl, haloalkyl, alkoxy, haloalkoxy, aryl, heteroaryl, cycloalkyl, or heterocyclyl wherein the aforementioned rings are optionally substituted with R ^a , R ^b , or R ^c independently selected from alkyl, halo, haloalkyl, alkoxy, haloalkoxy, hydroxy, cyano, monosubstituted amino, or disubstituted amino; or

R ¹ and R ² , when attached to the same carbon atom, can combine to form cycloalkyl or monocyclic saturated heterocyclyl to give a spiro ring wherein the cycloalkyl or monocyclic saturated heterocyclyl can be optionally substituted with R ^d , R ^c , or R ^f independently selected from alkyl, alkoxy, fluoro, fluoroalkyl, fluoroalkoxy, hydroxy, monosubstituted amino, or disubstituted amino; or

R ¹ and R ² , when attached to carbon atoms 2 and 5 or 3 and 6 positions of the piperazine ring, can combine to form -C ₁ -C ₃ - alkylene chain wherein one of the carbon atoms in the alkylene chain is optionally replaced by a -NR-, -O-, -S(O)n- (where R is hydrogen or alkyl and n is 0-2) and further wherein one or two hydrogen atoms in the alkylene chain can be optionally substituted with one or two alkyl;

R ³ , R ⁴ and R ⁵ are independently hydrogen, alkyl, fluoro, or fluoroalkyl; and Ar ¹ and Ar ² are independently aryl, heteroaryl, cycloalkyl, or heterocyclyl where each of the aforementioned ring is optionally substituted with R ^g , R ^h or R ⁱ where R ^g is alkyl, -C=C- R ⁶ (where R ⁶ is aryl or heteroaryl), halo, haloalkyl, haloalkoxy, alkylthio, cyano, alkoxy, amino, monosubstituted amino, disubstituted amino, sulfonyl, acyl, carboxy, alkoxycarbonyl, hydroxyalkyl, alkoxyalkyl, aminoalkyl, hydroxyalkoxy, alkoxyalkoxy, aminoalkoxy, aminosulfonyl, aminocarbonyl, or acylamino and R ^h and R ⁱ are independently selected from alkyl, halo, haloalkyl, haloalkoxy, alkylthio, cyano, alkoxy, amino, monosubstituted amino, disubstituted amino, sulfonyl, acyl, carboxy, alkoxycarbonyl, hydroxyalkyl, alkoxyalkyl, aminoalkyl, hydroxyalkoxy, alkoxyalkoxy, aminoalkoxy, aminosulfonyl, aminocarbonyl, acylamino, aryl., heteroaryl, cycloalkyl, or heterocyclyl where the aromatic or alicyclic ring- in R ^g , R ^h and R ⁱ is optionally substituted with R ^j , R ^k , or R ^l which are independently selected from alkyl, halo, haloalkyl, haloalkoxy, alkylthio, cyano, alkoxy, amino, monosubstituted amino, disubstituted amino, sulfonyl, acyl, carbpxy, alkoxycarbonyl, hydroxyalkyl, alkoxyalkyl, aminoalkyl, hydroxyalkoxy, alkoxyalkoxy, aminoalkoxy, aminosulfonyl, aminocarbonyl, or acylamino; or a pharmaceutically acceptable salt thereof provided that: the compound of Formula V is not 2-(4-benzhydrylpiperazin-l-yl)acetic acid, 2-(4- ((4- chlorophenyl)(phenyl)methyl)piperazin-l-yl)acetic acid, 2-((2R,5S)-4-((R)-(4-(lH- tetrazol-5- yl)phenyl)(3-hydroxyphenyl)methyl)-2,5-dimethylpiperazin-l-y l)acetic acid, or 2- ((2R,5S)- 4-((R)-(4-cyanophenyl)(3-hydroxyphenyl)methyl)-2,5-dimethylp iperazin-l-yl)acetic acid, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound having a formula of , or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound of Formula VI,

Formula VI, wherein:

A represents a group of general formula N Ri , a group of general formula N+(0-)R ₁ or a group of general formula N+(R')R ₁ , and in which Ri represents either a hydrogen atom, or a linear or branched (C ₁ -C ₇ )alkyl group optionally substituted with one or more fluorine atoms, or a (C ₄ -C ₇ )cycloalkyl group, or a (C ₃ -C ₇ )cycloalkyl(C ₁ -C ₃ )alkyl group, or a phenyl(C ₁ -C ₃ )alkyl group optionally substituted with one or two hydroxyl or methoxy groups, or a (C ₂ -C ₄ )alkenyl group, or a (C ₂ -C ₄ )alkynyl group, R' represents a linear or branched (C ₁ -C ₇ )alkyl group,

X represents a hydrogen atom or one or more substituents chosen from halogen atoms and trifluoromethyl, linear or branched (C1-C4)alkyl and (C ₁ -C ₄ )alkoxy groups,

R2 represents either a hydrogen atom, or one or more substituents chosen from halogen atoms and trifluoromethyl, (C ₁ -C ₄ )alkyl or (C ₁ -C ₄ )alkoxy groups, or amino groups of general formula NR ₃ R ₄ in which R ₃ and R ₄ each represent, independently of each other, a hydrogen atom or a (C ₁ -C ₄ )alkyl group, or form with the nitrogen atom carrying them a pyrrolidine, piperidine or morpholine ring, or a phenyl group optionally substituted with an atom or a group as defined for the symbol X above, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound having a formula of

, SSR-504734, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound of Formula VII,

Formula VII, wherein:

R ¹ is — (CH ₂ )n — R ^1a , wherein n is independently 0-6, and R ^1a is selected from the group consisting of: (1) C _1-6 alkyl, which is unsubstituted or substituted with 1-6 halogen, hydroxy,

(2) phenyl substituted with R ^2a , R ^2b and R ^2c ,

(3) C _3-6 cycloallyl, which is unsubstituted or substituted with C _1-6 alkyl, 1-6 halogen, hydroxy or — NR ¹⁰ R ¹¹ , (4) — O — C _1-6 alkyl, which is unsubstituted or substituted with 1-6 halogen, hydroxy or— NR ¹⁰ R ¹¹ ,

(5) — CO2R ⁹ , wherein R9 is independently selected from:

(a) hydrogen, (b) — C _1-6 alkyl, which is unsubstituted or substituted with 1-6 fluoro,

(c) benzyl, and

(d) phenyl,

(6) — NR ¹⁰ R ¹¹ , wherein R ¹⁰ and R ¹¹ are independently selected from: (a) hydrogen,

(b) — C _1-6 alkyl, which is unsubstituted or substituted with hydroxy, 1-6 fluoro or — NR ¹² R ¹³ , where R ¹² and R ¹³ are independently selected from hydrogen and — C _1-6 alkyl,

(c) — C _3-6 cycloalkyl, which is unsubstituted or substituted with hydroxy, 1 -6 fluoro or — NR ¹² R ¹³ , (d) benzyl,

(e) phenyl, and

(7) — CONR ¹⁰ R ¹¹ ;

R ² is selected from the group consisting of:

(1) phenyl, which is substituted with R ^2a , R ^2b and R ^2c , (2) C _1-8 alkyl, which is unsubstituted or substituted with 1-6 halogen, hydroxy, — NR ¹⁰ R ¹¹ , phenyl or heterocycle, where the phenyl or heterocycle is substituted with R ^2a , R ^2b and R ^2c ,

(3) C _3-6 cycloalkyl, which is unsubstituted or substituted with 1-6 halogen, hydroxy or — NR ¹⁰ R ¹¹ , and

(4) — C _1-6 alkyl-(C _3-6 cycloalkyl), which is unsubstituted or substituted with 1-6 halogen, hydroxy or — NR ¹⁰ R ¹¹ ;

R ^2a , R ^2b and R ^2c are independently selected from the group consisting of:

(I) hydrogen, (2) halogen,

(3) — C _1-6 alkyl, which is unsubstituted or substituted with:

(a) 1-6 halogen,

(b) phenyl,

(c) C _3-6 cycloalkyl, or (d) — NR ¹⁰ R ¹¹ ,

(4) — O — C _1-6 alkyl, which is unsubstituted or substituted with 1-6 halogen,

(5) hydroxy,

(6) — SCF ₃ ,

(7) — SCHF ₂ , (8) — SCH ₃ ,

(9) — CO ₂ R ⁹ ,

(10) — CN,

(I I) — SO ₂ R ⁹ ,

(12) — SO ₂ — NR ¹⁰ R ¹¹ ,

(13) — NR ¹⁰ R ¹¹ ,

(14) — CONR ¹⁰ R ¹¹ , and (15) — NO ₂ ;

R ³ is selected from the group consisting of:

(1) C _1-6 alkyl, which is unsubstituted or substituted with 1-6 halogen, hydroxyl, or — NR ¹⁰ R ¹¹ , (2) C _3-6 cycloalkyl, which is unsubstituted or substituted with 1 -6 halogen, hydroxyl c

— NR ¹⁰ R ¹¹ ,

R ⁴ and R ⁵ are independently selected from the group consisting of:

(1) hydrogen, and

(2) C _1-6 alkyl, which is unsubstituted or substituted with halogen or hydroxyl, or R ⁴ and R ⁵ taken together form a C _3-6 cycloalkyl ring;

A is selected from the group consisting of:

(1) — O — , and

(2) —NR ¹⁰ —; m is zero or one, whereby when m is zero R ² is attached directly to the carbonyl; and pharmaceutically acceptable salts thereof and individual enantiomers and diastereomers thereof, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound having a formula of

, or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt. In some embodiments of the methods and uses disclosed herein, the GlyT 1 inhibitor is a compound of Formula VIII,

Formula VIII, wherein:

R ¹ is phenyl independently substituted from 1 to 5 times with halogen, C ₁ -C ₃ alkyl, C ₃ - C ₆ cycloalkyl, OR ⁹ , or SR ¹⁰ , wherein C ₁ -C ₃ alkyl and C ₃ -C ₆ cycloalkyl are optionally substituted with 1 to 10 times with R ⁷ ;

R ² is H;

R ³ and R4 are each individually H or CH ₃ ;

R ⁵ is selected from the group consisting of:

(1) hydrogen,

(2) C ₁ -C ₆ alkyl which is optionally substituted from 1 to 11 times with R ⁷ ,

(3) gem-dialkyl, and

(4) gem-dihalo; or two R ⁵ substituents on the same carbon, together with the carbon atom to which they are attached, may form a 3-, 4-, or 5-membered cycloalkyl optionally substituted from 1 to 10 times with R ⁷ ; or two R ⁵ substituents on adjacent carbons of the ring to which they are attached, together may form a 3-, 4-, 5- or 6-membered cycloalkyl optionally substituted from 1 to 10 times with R ⁷ ; wherein E, F, and G are each independently nitrogen or carbon and R ^6a is C ₁ -C ₂ alkyl, which is optionally substituted 1 to 5 times with halogen or deuterium;

R ⁷ is selected from the group consisting of:

(1) hydrogen,

(2) halogen,

(3) deuterium,

(4) gem-dialkyl,

(5) gem-dihalo,

(6) —OR ⁹ , — NR ¹¹ R ¹² , — NR ¹¹ C(O) _P R ¹⁰ , — S(O) _P R ¹⁰ , — CN, — NO2, — C(O) _P R ¹⁰ , — C(O)NR ¹¹ R ¹² , or — NR ¹¹ C(S)R ¹⁰ , and

(7) oxo or thio;

R ⁸ is selected from the group consisting of:

(1) hydrogen,

(2) halogen,

(3) C ₁ -C ₆ alkyl, C ₂ -C ₆ alkenyl, C ₂ -C ₆ alkynyl, C ₃ -C ₇ cycloalkyl, or C ₄ -C ₇ cycloalkylalkyl, wherein each of the C ₁ -C ₆ alkyl, C ₂ -C ₆ alkenyl, C ₂ -C ₆ alkynyl, C ₃ -C ₇ cycloalkyl, and C ₄ -C ₇ cycloalkylalkyl is independently and optionally substituted from 1 to 11 times with R ⁷ , or

(4) —OR ⁹ , — NR ¹¹ R ¹² , — NR ¹¹ C(O) _P R ¹⁰ , — S(O) _P R ¹⁰ , — CN, — NO2, — C(O) _P R ¹⁰ , — C(O)NR ¹¹ R ¹² , or — NR ¹¹ C(S)R ¹⁰ ; R ⁹ is selected from the group consisting of hydrogen, C ₁ -C ₄ alkyl, C ₃ -C ₇ cycloalkyl, C ₄ -C ₇ cycloalkylalkyl, — C(O)NR ¹¹ R ¹² , and — C(O) _p R ¹⁰ , wherein each of C ₁ -C ₄ alkyl, C ₃ -C ₇ cycloalkyl, and C ₄ -C ₇ cycloalkylalkyl is optionally substituted from 1 to 11 times with R ⁷ ;

R ¹⁰ is selected from the group consisting of hydrogen, C ₁ -C ₄ alkyl, C ₃ -C ₇ cycloalkyl C ₄ -C ₇ cycloalkylalkyl, aryl, and heteroaryl, wherein each of C ₁ -C ₄ alkyl, C ₃ -C ₇ cycloalkyl, and C ₄ -C ₇ cycloalkylalkyl is optionally substituted from 1 to 11 times with substituents as defined in R7 and aryl or heteroaryl is optionally substituted from 1 to 10 times with R ⁸ ;

R ¹¹ and R ¹² are each independently selected from the group consisting hydrogen, C ₁ -C ₄ alkyl, C ₃ -C ₇ cycloalkyl, C ₄ -C ₇ cycloalkylalkyl, aryl, and heteroaryl, wherein each of C ₁ -C ₄ alkyl, C ₃ -C ₇ cycloalkyl, and C ₄ -C ₇ cycloalkylalkyl is optionally substituted from 1 to 11 times with substituents as defined in R ⁷ and aryl or heteroaryl is optionally substituted from 1 to 10 times with R ⁸ , or R ¹¹ and R ¹² are taken together with the nitrogen to which they are attached to form a saturated or partially saturated monocyclic or fused bicyclic heterocycle optionally substituted from 1 to 11 times with R ⁷ ;

A is X is N;

Y is N; p is 1, or 2; and m is 0; with the following provisos that: R ⁶ cannot be (a) lH-l,2,3-triazol-4-yl, or (b) 5- methylisoxazol-4-yl; or an oxide thereof, a pharmaceutically acceptable salt of the compound or its oxide, or an individual enantiomer or diastereomer thereof. In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is selected from any of the following:

’and , or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt. In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound having a formula of , or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound of Formula IX, Formula IX, wherein:

R ¹ represents phenyl or a 5 or 6 membered monocyclic heteroaryl having 1, 2, or 3 heteroatoms independently selected from O, N or S, wherein the phenyl or the heteroaryl is optionally substituted with one or more R ³ ;

R ² represents aryl, a 5 or 6 membered monocyclic heteroaryl or a 8 to 10 membered bicyclic heteroaryl, the mono- or bicyclic heteroaryl having 1, 2, or 3 heteroatoms independently selected from O, N or S, wherein the aryl or the heteroaryl is optionally substituted with one or more R ⁴ ;

R ³ is a halogen, a C _1-4 -alkyl or a C _3-6 -cycloalkyl, wherein the C _1-4 -alkyl or the C _3-6 -cycloalkyl is optionally substituted with one or more halogens; and

R ⁴ is a halogen, — CN, C _1-4 -alkyl, C _3-6 -cycloalkyl, — C _1-3 -alkyl — C _3-6 -cycloalkyl or — O — C ₁ - ₆ alkyl, wherein the C _1-4 -alkyl, C _3-6 -cycloalkyl, — C _1-3 -alkyl — C _3-6 -cycloalkyl or the — O — C _1-6 -alkyl is optionally substituted with one or more halogens; or a pharmaceutically acceptable salt thereof, or a tautomer or stereoisomer of the compound or its pharmaceutically acceptable salt, or a mixture of any of the foregoing.

In certain embodiments, the compound of Formula IX can be represented by a compound of formula IX(a): Formula IX(a), or a pharmaceutically acceptable salt thereof, or a tautomer the compound or its pharmaceutically acceptable salt, or a mixture of any of the foregoing.

In certain embodiments, the compound of Formula IX can be represented by a compound of formula IX(b): Formula IX(b), or a pharmaceutically acceptable salt thereof or a tautomer the compound or its pharmaceutically acceptable salt, or a mixture of any of the foregoing.

In certain embodiments, the compound of formula IX is a compound selected from any of the following, a stereoisomer or stereoisomeric mixture thereof, or a pharmaceutically acceptable salt thereof:

In some embodiments of the methods and uses disclosed herein, the GlyT1 inhibitor is a compound of Formula X,

Formula X, wherein:

R ¹ is selected from the group consisting of a) 5 or 6 membered monocyclic heteroaryl, having 1, 2, 3 or 4 heteroatoms independently selected from the group consisting of O, N and S(O)r, b) 5 or 6 membered monocyclic partially saturated heterocycloalkyl, having 1 , 2 or 3 heteroatoms independently selected from the group consisting of O, N and S(O)r, and c) 9 or 10 membered bicyclic heteroaryl, having 1 , 2 or 3 heteroatoms independently selected from the group consisting of O, N and S(O) _r , wherein r is 0, 1 or 2; wherein each of said groups a), b) and c) is optionally substituted with 1 or more substituents independently selected from the group consisting of C _1-4 -alkyl-, C _1-4 -alkyl-0 — , oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, C _3-6 -cycloalkyl- and C _3-6 -cycloalkyl- O — and in case a substituent is attached to a nitrogen ring atom said substituent is selected from the group consisting of C _1-4 -alkyl-, C _1-4 -alkyl-CO — , C _3-6 -cycloalkyl- and C _3-6 -cycloalkyl-CO — , and wherein each of said C _1-4 -alkyl-, C _1-4 -alkyl-O — , C _1-4 -alkyl-CO — , oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, C _3-6 -cycloalkyl-, C _3-6 -cycloalkyl-CO — or C _3-6 - cycloalkyl-O — substituents may be substituted by 1 or more substituents independently selected from the group consisting of fluoro, — CF ₃ , — CHF ₂ , — CH ₂ F and — CN;

R ² is selected from the group consisting of hydrogen, C _1-4 -alkyl-, C _1-4 -alkyl-O — , — CN and C _3-6 -cycloalkyl-, wherein each of said C _1-4 -alkyl-, C _1-4 -alkyl-O — and C _3-6 -cycloalkyl-group may be optionally substituted with 1, 2, 3 or more substituents independently selected from the group consisting of fluoro, — CF ₃ , — CHF ₂ , — CH ₂ F and — CN;

R ³ is selected from the group consisting of C _1-6 -alkyl-O — , C _3-6 -cycloalkyl-O — , morpholino, pyrazolyl and a 4 to 7 membered, monocyclic heterocycloalkyl-O — with 1 oxygen atom as ring member and optionally 1 or 2 heteroatoms independently selected from the group consisting of O, N and S(O) _s with s=0, 1 or 2, wherein said C _1-6 -alkyl-O — and said C _3-6 -cycloalkyl-O — may be optionally substituted with 1, 2, 3 or more substituents independently selected from the group consisting of fluoro, — CF ₃ , — CHF ₂ , — CH ₂ F, — CN, C _1-4 -alkyl-, C _3-6 -cycloalkyl-, C _1-6 -alkyl-O — and C _3-6 -cycloalkyl-O — ; R ⁴ is hydrogen; or R ³ and R ⁴ together with the ring atoms of the phenyl group to which they are bound may form a 4, 5 or 6 membered, monocyclic, partially saturated heterocycloalkyl or a heteroaryl each of which having 1, 2 or 3 heteroatoms independently selected from the group consisting of O, N and S(O) _s with s=0, 1 or 2, wherein there must be 1 ring oxygen atom that is directly attached to the ring carbon atom of said phenyl group to which R ³ is attached to in general formula (I); wherein said heterocycloalkyl group may be optionally substituted with 1, 2, 3 or more substituents independently selected from the group consisting of fluoro, — CF ₃ , — CHF ₂ , — CH ₂ F, — CN, C _1-4 -alkyl-, C _3-6 -cycloalkyl-, C _1-6 -alkyl-O — , C _3-6 -cycloalkyl- O — , oxetanyl-O — , tetrahydrofiiranyl-O — and tetrahydropyranyl-O — ;

R ⁵ is hydrogen;

R ⁶ is selected from the group consisting of hydrogen, C _1-4 -alkyl-S02 — , C _3-6 -cycloalkyl- SO ₂ and — CN;

R ⁷ is hydrogen; or one of the pairs a) R ⁶ and R ⁷ or b) R ⁶ and R ⁵ form together with the ring atoms of the phenyl group to which they are bound, a 5 or 6 membered, partially saturated monocyclic heterocycloalkyl group having 1, 2 or 3 heteroatoms independently selected from the group consisting of O, N and S(O) _u with u=0, 1 or 2, wherein there must be 1 — SO ₂ — member that is directly attached to the ring carbon atom of said phenyl group to which R ⁶ is attached to in general formula (I), wherein said heterocycloalkyl group may be optionally substituted with 1, 2, 3 or more substituents independently selected from the group consisting of fluoro, — CF ₃ , — CHF ₂ , — CH ₂ F, — CN, C _1-4 -alkyl-, C _1-6 -alkyl-O — and C _3-6 -cycloalkyl-O — or a pharmaceutically acceptable salt thereof, or a prodrug of the compound or its pharmaceutically acceptable salt.

In certain embodiments, the compound of formula X is a compound selected from any of the following, a stereoisomer or stereoisomeric mixture thereof, or a pharmaceutically acceptable salt thereof:

For example, the compound of Formula X could be a diastereomeric mixture or single diasteromer of any of the following, or a pharmaceutically acceptable salt thereof:

In certain embodiments, the compound of Formula X is a compound having a formula , or a pharmaceutically acceptable salt thereof. In some embodiments of the methods and uses disclosed herein, the GlyT 1 inhibitor is a compound of Formula XI,

Formula XI, wherein:

R ¹ is halogen, - OR ^{1 '} , - SR ^1" , cycloalkyl, cyclic amide, heterocycloalkyl, aryl or 5- or 6- membered hsteroaryl containing one, two or three heteroatoms selected from the group consisting of oxygen, sulphur and nitrogen; R ^{1 '} and R ^1" are each independently hydrogen, lower alkyl, lower alkyl substituted by halogen,

— (CH ₂ ) _x -cycloalkyl or — (CH ₂ ) _x -aryl ;

R ² is - S(O) ₂ -lower alkyl, — S(O) ₂ NH-lower alkyl, NO ₂ or CN; is an aromatic or partially aromatic bicyclic amine, having one or two additional N-atoms selected from the group consisting of

ύ: f =

«! i!· and wherein one of the additional N-ring atoms of the aromatic or partially aromatic bicyclic amine can be available in form of its oxide ; R3 to R10 are each independently hydrogen, hydroxy, halogen, =O, lower alkyl, cycloalkyl, heterocycloalkyl, lower alkoxy, CN, NO2, NH2, aryl, 5- or 6-membered heteroaryl containing one, two or three heteroatoms selected from the group consisting of oxygen, sulphur and nitrogen, — NH-lower alkyl, — N(lower alkyl)2, cyclic amide, — C(O)-cyclic amide, S-lower alkyl, — S(O)2-lower alkyl, lower alkyl substituted by halogen, lower alkoxy substituted by halogen, lower alkyl substituted by hydroxy, — O — (CH2)y-lower alkoxy, — 0(CH2)yC(O)N(lower alkyl)2, — C(O)-lower alkyl, —

O — (CH2)x-aryl, — O — (CH2)x-cycloalkyl, — O — (CH2)x-heterocycloalkyl, — C(O)O-lower alkyl, — C(O) — NH-lower alkyl, — C(O) — N( lower alkyl)2, 2-oxy-5- aza-bicyclo[2.2. l]hept-5-yl or 3-oxa-8-aza-bicyclo[3.2.1]oct-8-yl;

R, R', R" and R'" are each independently hydrogen or lower alkyl; or R' and R'" in group e) together with — (CH2)4 — form a six membered ring; and wherein all aryl-, cycloalkyl-, cyclic amide, heterocycloalkyl- or 5 or 6 membered heteroaryl groups as defined for R1, R1', R1" and R3 to R10 are unsubstituted or substituted by one or more substituents selected from the group consisting of hydroxy, =O, halogen, lower alkyl, phenyl, lower alkyl substituted by halogen and lower alkoxy; n, m, o, p, q, r, s and t are each independently 1 or 2; x is 0, 1 or 2; and y is 1 or 2; or a pharmaceutically acceptable salt thereof. In certain emodiments, the compound of formula XI, or a pharmaceutically acceptable salt thereof, is a compound of formula XI(a), , or a pharmaceutically acceptable salt therof, a compound of formula XI(b), , or a pharmaceutically acceptable salt therof, a compound of formula XI(c), , or a pharmaceutically acceptable salt therof, a compound of formula XI(d), , or a pharmaceutically acceptable salt therof, a compound of formula XI(e), , or a pharmaceutically acceptable salt therof, a compound of formula XI(f), , or a pharmaceutically acceptable salt therof, a compound of formula XI(g), , or a pharmaceutically acceptable salt therof, or a compound of formula XI (h), , or a pharmaceutically acceptable salt therof.

In certain embodiments, the compound of formula XI is a compound selected from any of the following, a stereoisomer or stereoisomeric mixture thereof, or a pharmaceutically acceptable salt thereof:

In certain of the methods and uses disclosed herein, the subject is a subject in need thereof In some embodiments of the uses and methods as disclosed herein, the glycine transporter inhibitor, such as a GlyT1 inhibitor ( e.g ., a GlyT1 inihibitor as disclosed herein), or a pharmaceutically acceptable salt thereof, or a prodrug of the glycine transporter inhibitor, such as a GlyT1 inhibitor (e.g., a GlyT1 inihibitor as disclosed herein), or its pharmaceutically acceptable salt is administered in a therapeutically effective amount. In some embodiments, a compound, or a pharmaceutically acceptable salt, solvate or prodrug thereof, is chosen from a compound of as described herein. Any of the compounds provided for herein can be prepared as pharmaceutically acceptable salts, solvates or prodrugs and/or as part of a pharmaceutical composition as descripted in the cited patents or patent application publications herein. Although the compounds described herein may be shown with specific stereochemistries around certain atoms, such as cis or trans, the compounds can also be made in the opposite orientation or in a racemic mixture. Such isomers or racemic mixtures are encompassed by the present disclosure. Additionally, although the compounds are shown collectively in a table, any compounds, or a pharmaceutically acceptable salt, solvate or prodrug thereof, can be chosen from the table and used in the embodiments provided for herein.

The compounds described herein can be made according to the methods described in the cited patents or patent application publications herein.

The compounds can be used to inhibit the GlyT1 transporter. Thus, in some embodiments, the compounds can be referred to as GlyT1 transporter inhibiting compounds or GlyT1 inhibitors.

The compounds described herein can be administered in any conventional manner by any route where they are active. Administration can be systemic, topical, or oral. For example, administration can be, but is not limited to, parenteral, subcutaneous, intravenous, intramuscular, intraperitoneal, transdermal, oral, buccal, sublingual, or ocular routes, or intravaginal, by inhalation, by depot injections, or by implants. The mode of administration can depend on the conditions or disease to be targeted or treated. The selection of the specific route of administration can be selected or adjusted by the clinician according to methods known to the clinician to obtain the desired clinical response.

In some embodiments, it may be desirable to administer one or more compounds, or a pharmaceutically acceptable salt, solvate or prodrug thereof, locally to an area in need of treatment. This may be achieved, for example, and not by way of limitation, by local infusion during surgery, topical application, e.g., in conjunction with a wound dressing after surgery, by injection, by means of a catheter, by means of a suppository, or by means of an implant, wherein the implant is of a porous, non-porous, or gelatinous material, including membranes, such as silastic membranes, or fibers.

The compounds described herein can be administered either alone or in combination (concurrently or serially) with other pharmaceuticals. For example, the compounds can be administered in combination with other drugs for the treatment of polycythemia and the like. Examples of other pharmaceuticals or medicaments are known to one of skill in the art and include, but are not limited to those described herein.

The means and methods for administration are known in the art and an artisan can refer to various pharmacologic references for guidance (see, for example, Modem Pharmaceutics, Banker & Rhodes, Marcel Dekker, Inc. (1979); and Goodman & Gilman’s The Pharmaceutical Basis of Therapeutics, 6th Edition, MacMillan Publishing Co., New York (1980)).

The amount of compound to be administered is that amount which is therapeutically effective. The dosage to be administered will depend on the characteristics of the subject being treated, e.g., the particular animal treated, age, weight, health, types of concurrent treatment, if any, and frequency of treatments, and can be easily determined by one of skill in the art (e.g., by the clinician). The standard dosing for protamine can be used and adjusted (i.e ., increased or decreased) depending upon the factors described above. The selection of the specific dose regimen can be selected or adjusted or titrated by the clinician according to methods known to the clinician to obtain the desired clinical response.

The amount of a compound described herein that will be effective in the treatment and/or prevention of a particular disease, condition, or disorder will depend on the nature and extent of the disease, condition, or disorder, and can be determined by standard clinical techniques. In addition, in vitro or in vivo assays may optionally be employed to help identify optimal dosage ranges. The precise dose to be employed in the compositions will also depend on the route of administration, and the seriousness of the disorder, and should be decided according to the judgment of the practitioner and each patient’s circumstances. However, a suitable dosage range for oral administration is, generally, from about 0.001 milligram to about 200 milligrams per kilogram body weight, from about 0.01 milligram to about 100 milligrams per kilogram body weight, from about 0.01 milligram to about 70 milligrams per kilogram body weight, from about 0.1 milligram to about 50 milligrams per kilogram body weight, from 0.5 milligram to about 20 milligrams per kilogram body weight, or from about 1 milligram to about 10 milligrams per kilogram body weight. In some embodiments, the oral dose is about 5 milligrams per kilogram body weight.

In some embodiments, suitable dosage ranges for intravenous (i.v.) administration are from about 0.01 mg to about 500 mg per kg body weight, from about 0.1 mg to about 100 mg per kg body weight, from about 1 mg to about 50 mg per kg body weight, or from about 10 mg to about 35 mg per kg body weight. Suitable dosage ranges for other modes of administration can be calculated based on the forgoing dosages as known by those skilled in the art. For example, recommended dosages for intranasal, transmucosal, intradermal, intramuscular, intraperitoneal, subcutaneous, epidural, sublingual, intracerebral, intravaginal, transdermal administration or administration by inhalation are in the range of from about 0.001 mg to about 200 mg per kg of body weight, from about 0.01 mg to about 100 mg per kg of body weight, from about 0.1 mg to about 50 mg per kg of body weight, or from about 1 mg to about 20 mg per kg of body weight. Effective doses may be extrapolated from dose- response curves derived from in vitro or animal model test systems. Such animal models and systems are well known in the art.

In certain embodiments, the glycine transporter inhibitor to be administered is a GlyT 1 inhibitor, such as a GlyT 1 inhibitor as disclosed herein. In some embodiments, suitable dosage ranges for the GlyT1 inhibitor are from about 5 mg/day to 200 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 5 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 10 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 15 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 20 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 25 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 30 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 35 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 40 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 45 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 50 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 55 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 60 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 65 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 70 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 75 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 80 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 85 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 90 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 95 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 100 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 105 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 110 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 115 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 120 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 125 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 130 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 135 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 140 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 145 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 150 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 155 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 160 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 165 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 170 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 175 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 180 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 185 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 190 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 195 mg/day. In some embodiments, the GlyT1 inhibitor is administered at 200 mg/day.

In certain embodiments, the glycine transporter inhibitor to be administered is a GlyT 1 inhibitor, such as bitopertin, pharmaceutically acceptable salt thereof, or a prodrug of bitopertin or its pharmaceutically acceptable salt. In some embodiments, the GlyT 1 inhibitor is bitopertin. In some embodiments, suitable dosage ranges for bitopertin are from about 5 mg/day to 200 mg/day. In some embodiments, bitopertin is administered at 5 mg/day. In some embodiments, bitopertin is administered at 10 mg/day. In some embodiments, bitopertin is administered at 15 mg/day. In some embodiments, bitopertin is administered at 20 mg/day. In some embodiments, bitopertin is administered at 25 mg/day. In some embodiments, bitopertin is administered at 30 mg/day. In some embodiments, bitopertin is administered at 35 mg/day. In some embodiments, bitopertin is administered at 40 mg/day. In some embodiments, bitopertin is administered at 45 mg/day. In some embodiments, bitopertin is administered at 50 mg/day. In some embodiments, bitopertin is administered at 55 mg/day. In some embodiments, bitopertin is administered at 60 mg/day. In some embodiments, bitopertin is administered at 65 mg/day. In some embodiments, bitopertin is administered at 70 mg/day. In some embodiments, bitopertin is administered at 75 mg/day. In some embodiments, bitopertin is administered at 80 mg/day. In some embodiments, bitopertin is administered at 85 mg/day. In some embodiments, bitopertin is administered at 90 mg/day. In some embodiments, bitopertin is administered at 95 mg/day. In some embodiments, bitopertin is administered at 100 mg/day. In some embodiments, bitopertin is administered at 105 mg/day. In some embodiments, bitopertin is administered at 110 mg/day. In some embodiments, bitopertin is administered at 115 mg/day. In some embodiments, bitopertin is administered at 120 mg/day. In some embodiments, bitopertin is administered at 125 mg/day. In some embodiments, bitopertin is administered at 130 mg/day. In some embodiments, bitopertin is administered at 135 mg/day. In some embodiments, bitopertin is administered at 140 mg/day. In some embodiments, bitopertin is administered at 145 mg/day. In some embodiments, bitopertin is administered at 150 mg/day. In some embodiments, bitopertin is administered at 155 mg/day. In some embodiments, bitopertin is administered at 160 mg/day. In some embodiments, bitopertin is administered at 165 mg/day. In some embodiments, bitopertin is administered at 170 mg/day. In some embodiments, bitopertin is administered at 175 mg/day. In some embodiments, bitopertin is administered at 180 mg/day. In some embodiments, bitopertin is administered at 185 mg/day. In some embodiments, bitopertin is administered at 190 mg/day. In some embodiments, bitopertin is administered at 195 mg/day. In some embodiments, bitopertin is administered at 200 mg/day.

The compounds described herein can be formulated for parenteral administration by injection, such as by bolus injection or continuous infusion. In some embodiments, the compounds can be administered by continuous infusion subcutaneously over a period of about 15 minutes to about 24 hours. Formulations for injection can be presented in unit dosage form, such as in ampoules or in multi-dose containers, with an optionally added preservative. The compositions can take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and can contain formulatory agents such as suspending, stabilizing and/or dispersing agents. In some embodiments, the injectable is in the form of short-acting, depot, or implant and pellet forms injected subcutaneously or intramuscularly. In some embodiments, the parenteral dosage form is the form of a solution, suspension, emulsion, or dry powder.

For oral administration, the compounds described herein can be formulated by combining the compounds with pharmaceutically acceptable carriers well known in the art. Such carriers enable the compounds to be formulated as tablets, pills, dragees, capsules, emulsions, liquids, gels, syrups, caches, pellets, powders, granules, slurries, lozenges, aqueous or oily suspensions, and the like, for oral ingestion by a patient to be treated. Pharmaceutical preparations for oral use can be obtained by, for example, adding a solid excipient, optionally grinding the resulting mixture, and processing the mixture of granules, after adding suitable auxiliaries, if desired, to obtain tablets or dragee cores. Suitable excipients include, but are not limited to, fillers such as sugars, including, but not limited to, lactose, sucrose, mannitol, and sorbitol; cellulose preparations such as, but not limited to, maize starch, wheat starch, rice starch, potato starch, gelatin, gum tragacanth, methyl cellulose, hydroxypropylmethyl-cellulose, sodium carboxymethylcellulose, and polyvinylpyrrolidone (PVP). If desired, disintegrating agents can be added, such as, but not limited to, the cross-linked polyvinyl pyrrolidone, agar, or alginic acid or a salt thereof such as sodium alginate.

Orally administered compositions can contain one or more optional agents, for example, sweetening agents such as fructose, aspartame or saccharin; flavoring agents such as peppermint, oil of wintergreen, or cherry; coloring agents; and preserving agents, to provide a pharmaceutically palatable preparation. Moreover, where in tablet or pill form, the compositions may be coated to delay disintegration and absorption in the gastrointestinal tract thereby providing a sustained action over an extended period of time. Selectively permeable membranes surrounding an osmotically active driving compound are also suitable for orally administered compounds. Oral compositions can include standard vehicles such as mannitol, lactose, starch, magnesium stearate, sodium saccharine, cellulose, magnesium carbonate, etc. Such vehicles are suitably of pharmaceutical grade.

Dragee cores can be provided with suitable coatings. For this purpose, concentrated sugar solutions can be used, which can optionally contain gum arabic, talc, polyvinyl pyrrolidone, carbopol gel, polyethylene glycol, and/or titanium dioxide, lacquer solutions, and suitable organic solvents or solvent mixtures. Dyestuffs or pigments can be added to the tablets or dragee coatings for identification or to characterize different combinations of active compound doses.

Pharmaceutical preparations which can be used orally include, but are not limited to, push-fit capsules made of gelatin, as well as soft, sealed capsules made of gelatin and a plasticizer, such as glycerol or sorbitol. The push-fit capsules can contain the active ingredients in admixture with filler such as lactose, binders such as starches, and/or lubricants such as talc or magnesium stearate and, optionally, stabilizers. In soft capsules, the active compounds can be dissolved or suspended in suitable liquids, such as fatty oils, liquid paraffin, or liquid polyethylene glycols. In addition, stabilizers can be added. For buccal administration, the compositions can take the form of, such as, tablets or lozenges formulated in a conventional manner.

For administration by inhalation, the compounds described herein can be delivered in the form of an aerosol spray presentation from pressurized packs or a nebulizer, with the use of a suitable propellant, such as dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, carbon dioxide or other suitable gas. In the case of a pressurized aerosol the dosage unit can be determined by providing a valve to deliver a metered amount. Capsules and cartridges of, such as gelatin for use in an inhaler or insufflator can be formulated containing a powder mix of the compound and a suitable powder base such as lactose or starch.

The compounds described herein can also be formulated in rectal compositions such as suppositories or retention enemas, such as containing conventional suppository bases such as cocoa butter or other glycerides. The compounds described herein can also be formulated in vaginal compositions such as vaginal creams, suppositories, pessaries, vaginal rings, and intrauterine devices.

In transdermal administration, the compounds can be applied to a plaster, or can be applied by transdermal, therapeutic systems that are consequently supplied to the organism.

In some embodiments, the compounds are present in creams, solutions, powders, fluid emulsions, fluid suspensions, semi-solids, ointments, pastes, gels, jellies, and foams, or in patches containing any of the same.

The compounds described herein can also be formulated as a depot preparation.

Such long acting formulations can be administered by implantation (for example subcutaneously or intramuscularly) or by intramuscular injection. Depot injections can be administered at about 1 to about 6 months or longer intervals. Thus, for example, the compounds can be formulated with suitable polymeric or hydrophobic materials (for example as an emulsion in an acceptable oil) or ion exchange resins, or as sparingly soluble derivatives, for example, as a sparingly soluble salt.

In some embodiments, the compounds can be delivered in a controlled release system. In one embodiment, a pump may be used (see Langer, supra; Sefton, CRC Crit. Ref. Biomed. Eng., 1987, 14, 201; Buchwald et ah, Surgery, 1980, 88, 507 Saudek et al, N. Engl. J. Med., 1989, 321, 574). In some embodiments, polymeric materials can be used (see Medical Applications of Controlled Release, Langer and Wise (eds.), CRC Pres., Boca Raton, Fla. (1974); Controlled Drug Bioavailability, Drug Product Design and Performance, Smolen and Ball (eds.), Wiley, New York (1984); Ranger et al, J. Macromol. Sci. Rev. Macromol. Chem., 1983, 23, 61; see, also Levy et al, Science, 1985, 228, 190; During et al, Ann. Neurol., 1989, 25, 351; Howard et al, J. Neurosurg., 1989, 71, 105). In yet another embodiment, a controlled-release system can be placed in proximity of the target of the compounds described herein, such as the liver, thus requiring only a fraction of the systemic dose (see, e.g., Goodson, in Medical Applications of Controlled Release, supra, vol. 2, pp. 115-138 (1984)). Other controlled-release systems discussed in the review by Langer,

Science, 1990, 249, 1527-1533) may be used.

It is also known in the art that the compounds can be contained in such formulations with pharmaceutically acceptable diluents, fillers, disintegrants, binders, lubricants, surfactants, hydrophobic vehicles, water soluble vehicles, emulsifiers, buffers, humectants, moisturizers, solubilizers, preservatives and the like. The pharmaceutical compositions can also comprise suitable solid or gel phase carriers or excipients. Examples of such carriers or excipients include, but are not limited to, calcium carbonate, calcium phosphate, various sugars, starches, cellulose derivatives, gelatin, and polymers such as polyethylene glycols. In some embodiments, the compounds described herein can be used with agents including, but not limited to, topical analgesics (e.g., lidocaine), barrier devices (e.g., GelClair), or rinses (e.g., Caphosol).

In some embodiments, the compounds described herein can be delivered in a vesicle, in particular a liposome (see, Langer, Science, 1990, 249, 1527-1533; Treat et al, in Liposomes in the Therapy of Infectious Disease and Cancer, Lopez-Berestein and Fidler (eds.), Liss, New York, pp. 353-365 (1989); Lopez-Berestein, ibid., pp. 317-327; see generally ibid.).

Suitable compositions include, but are not limited to, oral non-absorbed compositions. Suitable compositions also include, but are not limited to saline, water, cyclodextrin solutions, and buffered solutions of pH 3-9.

The compounds described herein, or pharmaceutically acceptable salts, solvates or prodrugs thereof, can be formulated with numerous excipients including, but not limited to, purified water, propylene glycol, PEG 400, glycerin, DMA, ethanol, benzyl alcohol, citric acid/sodium citrate (pH3), citric acid/sodium citrate (pH5), tris(hydroxymethyl)amino methane HC1 (pH7.0), 0.9% saline, and 1.2% saline, and any combination thereof. In some embodiments, excipient is chosen from propylene glycol, purified water, and glycerin.

In some embodiments, the formulation can be lyophilized to a solid and reconstituted with, for example, water prior to use.

When administered to a mammal ( e.g . , to an animal for veterinary use or to a human for clinical use) the compounds can be administered in isolated form.

When administered to a human, the compounds can be sterile. Water is a suitable carrier when the compound of Formula I-VIII is administered intravenously. Saline solutions and aqueous dextrose and glycerol solutions can also be employed as liquid carriers, particularly for injectable solutions. Suitable pharmaceutical carriers also include excipients such as starch, glucose, lactose, sucrose, gelatin, malt, rice, flour, chalk, silica gel, sodium stearate, glycerol monostearate, talc, sodium chloride, dried skim milk, glycerol, propylene, glycol, water, ethanol and the like. The present compositions, if desired, can also contain minor amounts of wetting or emulsifying agents, or pH buffering agents.

The compositions described herein can take the form of a solution, suspension, emulsion, tablet, pill, pellet, capsule, capsule containing a liquid, powder, sustained-release formulation, suppository, aerosol, spray, or any other form suitable for use. Examples of suitable pharmaceutical carriers are described in Remington’s Pharmaceutical Sciences, A.R. Gennaro (Editor) Mack Publishing Co.

In some embodiments, the compounds are formulated in accordance with routine procedures as a pharmaceutical composition adapted for administration to humans. Typically, compounds are solutions in sterile isotonic aqueous buffer. Where necessary, the compositions can also include a solubilizing agent. Compositions for intravenous administration may optionally include a local anesthetic such as lidocaine to ease pain at the site of the injection. Generally, the ingredients are supplied either separately or mixed together in unit dosage form, for example, as a dry lyophilized powder or water free concentrate in a hermetically sealed container such as an ampoule or sachette indicating the quantity of active agent. Where the compound is to be administered by infusion, it can be dispensed, for example, with an infusion bottle containing sterile pharmaceutical grade water or saline. Where the compound is administered by injection, an ampoule of sterile water for injection or saline can be provided so that the ingredients may be mixed prior to administration.

The pharmaceutical compositions can be in unit dosage form. In such form, the composition can be divided into unit doses containing appropriate quantities of the active component. The unit dosage form can be a packaged preparation, the package containing discrete quantities of the preparations, for example, packeted tablets, capsules, and powders in vials or ampules. The unit dosage form can also be a capsule, cachet, or tablet itself, or it can be the appropriate number of any of these packaged forms.

In some embodiments, a composition is in the form of a liquid wherein the active agent (i.e., one of the facially amphiphilic polymers or oligomers disclosed herein) is present in solution, in suspension, as an emulsion, or as a solution/suspension. In some embodiments, the liquid composition is in the form of a gel. In other embodiments, the liquid composition is aqueous. In other embodiments, the composition is in the form of an ointment.

In some embodiments, the composition is in the form of a solid article. For example, in some embodiments, the ophthalmic composition is a solid article that can be inserted in a suitable location in the eye, such as between the eye and eyelid or in the conjunctival sac, where it releases the active agent as described, for example, U.S. Pat. No. 3,863,633; U.S.

Pat. No. 3,867,519; U.S. Pat. No. 3,868,445; U.S. Pat. No. 3,960,150; U.S. Pat. No. 3,963,025; U.S. Pat. No. 4,186,184; U.S. Pat. No. 4,303,637; U.S. Pat. No. 5,443,505; and U.S. Pat. No. 5,869,079. Release from such an article is usually to the cornea, either via the lacrimal fluid that bathes the surface of the cornea, or directly to the cornea itself, with which the solid article is generally in intimate contact. Solid articles suitable for implantation in the eye in such fashion are generally composed primarily of polymers and can be bioerodible or non-bioerodible. Bioerodible polymers that can be used in the preparation of ocular implants carrying one or more of compounds include, but are not limited to, aliphatic polyesters such as polymers and copolymers of poly(glycolide), poly(lactide), poly(epsilon-caprolactone), poly-(hydroxybutyrate) and poly(hydroxyvalerate), polyamino acids, polyorthoesters, polyanhydrides, aliphatic polycarbonates and polyether lactones. Suitable non-bioerodible polymers include silicone elastomers. The compositions described herein can contain preservatives. Suitable preservatives include, but are not limited to, mercury-containing substances such as phenylmercuric salts ( e.g ., phenylmercuric acetate, borate and nitrate) and thimerosal; stabilized chlorine dioxide; quaternary ammonium compounds such as benzalkonium chloride, cetyltrimethylammonium bromide and cetylpyridinium chloride; imidazolidinyl urea; parabens such as methylparaben, ethylparaben, propylparaben and butylparaben, and salts thereof; phenoxyethanol; chlorophenoxyethanol; phenoxypropanol; chlorobutanol; chlorocresol; phenylethyl alcohol; disodium EDTA; and sorbic acid and salts thereof.

Optionally one or more stabilizers can be included in the compositions to enhance chemical stability where required. Suitable stabilizers include, but are not limited to, chelating agents or complexing agents, such as, for example, the calcium complexing agent ethylene diamine tetraacetic acid (EDTA). For example, an appropriate amount of EDTA or a salt thereof, e.g. , the disodium salt, can be included in the composition to complex excess calcium ions and prevent gel formation during storage. EDTA or a salt thereof can suitably be included in an amount of about 0.01% to about 0.5%. In those embodiments containing a preservative other than EDTA, the EDTA or a salt thereof, more particularly disodium EDTA, can be present in an amount of about 0.025% to about 0.1% by weight.

One or more antioxidants can also be included in the compositions. Suitable antioxidants include, but are not limited to, ascorbic acid, sodium metabisulfite, sodium bisulfite, acetylcysteine, polyquatemium- 1 , benzalkonium chloride, thimerosal, chlorobutanol, methyl paraben, propyl paraben, phenylethyl alcohol, edetate disodium, sorbic acid, or other agents know to those of skill in the art. Such preservatives are typically employed at a level of from about 0.001% to about 1.0% by weight.

In some embodiments, the compounds are solubilized at least in part by an acceptable solubilizing agent. C ₆ rtain acceptable nonionic surfactants, for example polysorbate 80, can be useful as solubilizing agents, as can ophthalmically acceptable glycols, polyglycols, e.g. , polyethylene glycol 400 (PEG-400), and glycol ethers.

Suitable solubilizing agents for solution and solution/suspension compositions are cyclodextrins. Suitable cyclodextrins can be chosen from α-cyclodextrin, β-cyclodextrin, g-cyclodextrin, alkyl cyclodextrins ( e.g ., methyl- β-cyclodextrin, dimethyl-β-cyclodextrin, diethyl-β-cyclodextrin), hydroxyalkylcyclodextrins (e.g., hydroxyethyl-β-cyclodextrin, hydroxypropyl- β-cyclodextrin), carboxy-alkylcyclodextrins (e.g., carboxymethyl- β- cyclodextrin), sulfoalkylether cyclodextrins (e.g., sulfobutylether-β-cyclodextrin), and the like. Ophthalmic applications of cyclodextrins have been reviewed in Rajewski et ah, Journal of Pharmaceutical Sciences, 1996, 85, 1155-1159.

In some embodiments, the composition optionally contains a suspending agent. For example, in those embodiments in which the composition is an aqueous suspension or solution/suspension, the composition can contain one or more polymers as suspending agents. Useful polymers include, but are not limited to, water-soluble polymers such as cellulosic polymers, for example, hydroxypropyl methylcellulose, and water- insoluble polymers such as cross-linked carboxyl-containing polymers.

One or more acceptable pH adjusting agents and/or buffering agents can be included in the compositions, including acids such as acetic, boric, citric, lactic, phosphoric and hydrochloric acids; bases such as sodium hydroxide, sodium phosphate, sodium borate, sodium citrate, sodium acetate, sodium lactate and tris-hydroxymethylaminomethane; and buffers such as citrate/dextrose, sodium bicarbonate and ammonium chloride. Such acids, bases and buffers are included in an amount required to maintain pH of the composition in an acceptable range.

One or more acceptable salts, solvates or prodrugs can be included in the compositions in an amount required to bring osmolality of the composition into an acceptable range. Such salts include, but are not limited to, those having sodium, potassium or ammonium cations and chloride, citrate, ascorbate, borate, phosphate, bicarbonate, sulfate, thiosulfate or bisulfite anions. In some embodiments, salts include sodium chloride, potassium chloride, sodium thiosulfate, sodium bisulfite and ammonium sulfate. In some embodiments, the salt is sodium chloride.

Optionally one or more acceptable surfactants, such as, but not limited to, nonionic surfactants, or co-solvents can be included in the compositions to enhance solubility of the components of the compositions or to impart physical stability, or for other purposes.

Suitable nonionic surfactants include, but are not limited to, polyoxyethylene fatty acid glycerides and vegetable oils, e.g. , polyoxyethylene (60) hydrogenated castor oil; and polyoxyethylene alkyl ethers and alkylphenyl ethers, e.g., octoxynol 10, octoxynol 40; polysorbate 20, 60 and 80; polyoxyethylene/polyoxypropylene surfactants (e.g., Pluronic® F- 68, F84 and P-103); cyclodextrin; or other agents known to those of skill in the art. Typically, such co-solvents or surfactants are employed in the compositions at a level of from about 0.01% to about 2% by weight.

In some embodiments, pharmaceutical packs or kits comprising one or more containers filled with one or more compounds described herein are provided. Optionally associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals or biological products, which notice reflects approval by the agency of manufacture, use or sale for human administration for treating a condition, disease, or disorder described herein. In some embodiments, the kit contains more than one compound described herein. In some embodiments, the kit comprises a compound described herein in a single injectable dosage form, such as a single dose within an injectable device such as a syringe with a needle.

In some embodiments, the methods comprise administering to the subject one or more compounds described herein or a pharmaceutically acceptable salt, solvate or prodrug thereof, or a pharmaceutical composition of the same. In some embodiments, the subject is a subject in need of such treatment. As described herein, in some embodiments, the subject is a mammal, such as, but not limited to, a human.

In some embodiments, also provided are one or more compounds described above, or a pharmaceutically acceptable salt, solvate or prodrug thereof, or a pharmaceutical composition comprising one or more compounds described above, for use in the manufacture of a medicament for the treatment of methods of treating and/or preventing polycythemia, or related syndrome thereof, including, but not limited to the conditions described herein, in a subject, such as those described herein. In some embodiments, the subject is a subject in need thereof.

The present embodiments also provides the use of one or more compounds described above, or a pharmaceutically acceptable salt, solvate or prodrug thereof, or a pharmaceutical composition comprising one or more compounds described above, in the inhibition of a GlyT 1 transporter, such as the presence on the surface of the cell. In some embodiments, the compounds, pharmaceutically acceptable salt thereof, or a pharmaceutical composition of the same inhibit the internalization, trafficking, and/or degradation of the GlyT1 transporter.

As used herein, “inhibition” can refer to either inhibition of a specific activity. The activity of a GlyT 1 transporter can be measured by any method known in the art including but not limited to the methods described herein.

The compounds described herein are inhibitors of the GlyT1 transporter. The ability of the compounds to inhibit GlyT 1 transporter activity may be measured using any assay known in the art.

Generally, assays for testing compounds that inhibit GlyT1 transporter activity include the determination of any parameter that is indirectly or directly under the influence of a GlyT1 transporter, e.g., a functional, physical, or chemical effect.

Samples or assays comprising GlyT 1 transporters that are treated with a potential inhibitor, are compared to control samples without the inhibitor to examine the extent of inhibition. Control samples (untreated with inhibitors) are assigned a relative GlyT 1 transporter activity value of 100%. Inhibition of a GlyT1 transporter is achieved when the GlyT1 transporter activity value relative to the control is about 80%, 50%, or 25%.

Ligand binding to a GlyT1 transporter can be tested in a number of formats. Binding can be performed in solution, in a bilayer membrane, attached to a solid phase, in a lipid monolayer, or in vesicles. For example, in an assay, the binding of the natural ligand to its transporter is measured in the presence of a candidate modulator, such as the compound described herein. Alternatively, the binding of the candidate modulator may be measured in the presence of the natural ligand. Often, competitive assays that measure the ability of a compound to compete with binding of the natural ligand to the transporter are used. Binding can be tested by measuring, e.g., changes in spectroscopic characteristics (e.g., fluorescence, absorbance, refractive index), hydrodynamic (e.g., shape) changes, or changes in chromatographic or solubility properties.

After the transporter is expressed in cells, the cells can be grown in appropriate media in the appropriate cell plate. The cells can be plated, for example at 5000-10000 cells per well in a 384 well plate. In some embodiments, the cells are plated at about 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, or 10000 cells/per well. The plates can have any number of wells and the number of cells can be modified accordingly.

Any medicament having utility in an application described herein can be used in co- therapy, co-administration or co-formulation with a composition as described above. Therefore, the compounds described herein can be administered either before, concurrently with, or after such therapeutics are administered to a subject.

The additional medicament can be administered in co-therapy (including co- formulation) with the one or more of the compounds described herein.

In some embodiments, the response of the disease or disorder to the treatment is monitored and the treatment regimen is adjusted if necessary in light of such monitoring.

Frequency of administration is typically such that the dosing interval, for example, the period of time between one dose and the next, during waking hours is from about 1 to about 24, about 2 to about 12 hours, from about 3 to about 8 hours, or from about 4 to about 6 hours. In some embodiments, the dose is administered 1, 2, 3, or 4 times a day. It will be understood by those of skill in the art that an appropriate dosing interval is dependent to some degree on the length of time for which the selected composition is capable of maintaining a concentration of the compound(s) in the subject and/or in the target tissue ( e.g ., above the EC50 (the minimum concentration of the compound which inhibits the transporter’s activity by 90%). Ideally the concentration remains above the EC50 for at least 100% of the dosing interval. Where this is not achievable it is desired that the concentration should remain above the EC50 for at least about 60% of the dosing interval or should remain above the EC50 for at least about 40% of the dosing interval.

Methods of Use

The present application provides methods of preventing or treating polycythemia in a subject, the method comprising administering to the subject one or more glycine transporter inhibitor or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor or its pharmaceutically acceptable salt. In certain embodiments, the glycine transporter inhibitor is a GlyT1 inhibitor, such as a GlyT1 inhibitor as disclosed herein. For example, the present application provides a method of preventing, treating, or reducing the progression rate and/or severity of polycythemia in a subject, comprising administering to the subject bitopertin, pharmaceutically acceptable salt thereof, or a prodrug of bitopertin or its pharmaceutically acceptable salt.

In part, the present disclosure relates to methods of treating polycythemia in a subject, the method comprising administering to the subject a pharmaceutical composition comprising one or more glycine transporter inhibitor ( e.g ., a GlyT1 inhibitor), or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor) or its salt. In some embodiments, the disclosure relates to methods of preventing, treating, or reducing the progression rate and/or severity of one or more complications of polycythemia in a subject, the method comprising administering to the subject a pharmaceutical composition comprising one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor), or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor) or its salt. In some embodiments, the polycythemia is primary polycythemia (e.g. , polycythemia vera). In some embodiments, the polycythemia is secondary polycythemia. In some embodiments, the polycythemia is relative polycythemia. In some embodiments, the polycythemia is Chuvash polycythemia. The terms "subject," an "individual," or a "patient" are interchangeable throughout the specification and refer to either a human or a non-human animal. These terms include mammals, such as humans, non-human primates, laboratory animals, livestock animals (including bovines, porcines, camels, etc.), companion animals (e.g., canines, felines, other domesticated animals, etc.) and rodents (e.g., mice and rats). In particular embodiments, the patient, subject or individual is a human.

The present application provides methods of preventing, treating, or reducing the progression rate and/or severity of polycythemia (e.g., polycythemia vera) in a subject, the method comprising administering to the subject one or more glycine transporter inhibitor, or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor or its pharmaceutically acceptable salt. In some embodiments, the one or more glycine transporter inhibitor is one or more GlyT1 and/or GlyT2 inhibitors. In some embodiments, the one or more glycine transporter inhibitor is one or more GlyT 1 inhibitors, such as one or more GlyT1 inhibitors as disclosed herein. In certain embodiments of the foregoing, the pharmaceutical composition further comprises a pharmaceutically acceptable carrier. For example, the present application provides a method of preventing, treating, or reducing the progression rate and/or severity of polycythemia ( e.g ., polycythemia vera) in a subject, comprising administering to the subject bitopertin, or a pharmaceutically acceptable salt thereof, or a prodrug of bitopertin or its pharmaceutically acceptable salt.

The present application further provides use of one or more glycine transporter inhibitor, or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor or its pharmaceutically acceptable salt, in the manufacture of a formulation for the treatment of polycythemia in a subject. In some embodiments, the one or more glycine transporter inhibitor is one or more GlyT1 and/or GlyT2 inhibitors. In some embodiments, the one or more glycine transporter inhibitor is one or more GlyT 1 inhibitor, such as one or more GlyT1 inhibitor as disclosed herein. In certain such embodiments, the GlyT 1 inhibitor is bitopertin, or a pharmaceutically acceptable salt thereof, or a prodrug of bitopertin or its pharmaceutically acceptable salt. In certain embodiments of the foregoing, the formulation is administered in a therapeutically effective amount.

Polycythemia

Polycythemia, or erythrocytosis, is a disease characterized by an abnormally high level of red blood cells, which often leads to hyperviscosity and an increased risk of thrombosis. The increase in red blood cells can be due to an increase in the red blood cell mass ("absolute polycythemia") or to a decrease in the volume of plasma ("relative polycythemia"). Absolute polycythemia can be distinguished from relative polycythemia secondary to fluid loss or decreased intake, because absolute polycythemia results in increased total blood volume, and relative polycythemia does not. Two basic categories of polycythemia are typically recognized: primary polycythemias, which are due to factors intrinsic to red cell precursors and include the diagnoses of polycythemia vera and pure erythrocytosis, and secondary polycythemias, which are caused by factors extrinsic to red cell precursors.

Primary polycythemia

Primary polycythemia refers to a variety of myeloproliferative syndromes that include, for example, polycythemia vera and pure erythrocytosis. Polycythemia vera has a significant genetic component. For instance, an activating mutation in the tyrosine kinase JAK2 (JAK2V617F) is responsible for most primary cases in adults. Several other mutations in JAK2 have also been described ( e.g ., exon 12, JAK2H538-K539delinsI). These and possibly other JAK2 mutations are thought to cause hypersensitivity to EPO via the EPO receptor. Familial clustering suggests a genetic predisposition. Also, the clonality of polycythemia vera is well established. Studies also suggest hypersensitivity of the myeloid progenitor cells to growth factors, including EPO, IL-3, SCF, GM-CSF, and insulin-like growth factor (IGF)-1, whereas other studies show defects in programmed cell death. Pure erythrocytosis includes patients who have an isolated elevated RBC mass in the absence of any other precipitating factor.

Primary familial polycythemia is caused by a hypersensitivity of erythroid precursors to EPO. Several mutations (approximately 14) have been identified in the EPO receptor gene (EPOR). Most of the identified EPOR mutations cause truncation of the c-terminal cytoplasmic receptor domain of the receptor. These truncated receptors have heightened sensitivity to circulating EPO due to a lack of negative feedback regulation.

In certain aspects, the disclosure relates to methods of treating polycythemia in a subject, the method comprising administering to the subject a pharmaceutical composition comprising one or more glycine transporter inhibitor (e.g. , a GlyT 1 inhibitor), or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor) or its salt. In some embodiments, the polycythemia is primary polycythemia. In some embodiments, the primary polycythemia is polycythemia vera. In some embodiments, the primary polycythemia is pure erythrocytosis. In some embodiments, the primary polycythemia is primary familial polycythemia. As such, GlyT 1 inhibitors disclosed herein may be used in treating or reducing the risk of primary polycythemia, such as polycythemia vera, pure erythrocytosis, or primary familial polycythemia.

In certain aspects, the disclosure relates to methods of preventing, treating, or reducing the progression rate and/or severity of one or more complications of polycythemia in a subject, the method comprising administering to the subject a pharmaceutical composition comprising one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor), or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor) or its salt. In some embodiments, the one or more complications of polycythemia is selected from the group consisting of: pulmonary embolisms, transient ischemic attacks, transient visual defects, deep vein thrombosis, splenomegaly, hepatomegaly, myelofibrosis, and acute myeloid leukemia. In some embodiments, the myelofibrosis is selected from the group consisting of low-risk myelofibrosis, intermediate-risk myelofibrosis, high-risk myelofibrosis, primary myelofibrosis, post-essential thrombocythemia myelofibrosis, and post-polycythemia vera myelofibrosis.

In certain aspects, the disclosure relates to methods of treating splenomegaly associated with polycythemia in a subject, the method comprising administering to the subject a pharmaceutical composition comprising one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor), or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor) or its salt. In some embodiments, the subject has an increased spleen size (e.g., splenomegaly). In some embodiments, the GlyT1 inhibitors disclosed herein reduce splenomegaly in a subject with polycythemia. In some embodiments, the method reduces the subject’s spleen size. In some embodiments, the method reduces the subject’s spleen size by at least 10% (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method reduces the subject’s spleen size by at least 15%. In some embodiments, the method reduces the subject’s spleen size by at least 20%. In some embodiments, the method reduces the subject’s spleen size by at least 25%. In some embodiments, the method reduces the subject’s spleen size by at least 30%. In some embodiments, the method reduces the subject’s spleen size by at least 35%. In some embodiments, the method reduces the subject’s spleen size by at least 40%. In some embodiments, the method reduces the subject’s spleen size by at least 45%. In some embodiments, the method reduces the subject’s spleen size by at least 50%. In some embodiments, the method reduces the subject’s spleen size by at least 55%. In some embodiments, the method reduces the subject’s spleen size by at least 60%. In some embodiments, the method reduces the subject’s spleen size by at least 65%. In some embodiments, the method reduces the subject’s spleen size by at least 70%. In some embodiments, the method reduces the subject’s spleen size by at least 75%. In some embodiments, the method reduces the subject’s spleen size by at least 80%. In some embodiments, the method reduces the subject’s spleen size by at least 85%. In some embodiments, the method reduces the subject’s spleen size by at least 90%. In some embodiments, the method reduces the subject’s spleen size by at least 95%. In some embodiments, the method reduces the subject’s spleen size by at least 100%.

In certain aspects, the disclosure relates to methods of treating polycythemia associated with Janus Kinase 2 (JAK2) mutation in a subject, the method comprising administering to the subject a pharmaceutical composition comprising one or more glycine transporter inhibitor ( e.g . , a GlyT 1 inhibitor), or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor) or its salt. In some embodiments, the mutation in JAK2 is a JAK2 V617F exon 14 mutation. In some embodiments, the mutation in JAK2 is a JAK2 exon 12 mutation. In some embodiments, the mutation in JAK2 is a gain-of-function mutation. In some embodiments, the subject’s JAK2 enzyme activity is increased.

In certain aspects, the disclosure relates to methods of treating polycythemia associated with a gene mutation in a subject, the method comprising administering to the subject a pharmaceutical composition comprising one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor), or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor) or its salt. In some embodiments, the subject has a mutation in Tet Methylcytosine Dioxygenase 2 (TET2) or Nuclear Factor Erythroid 2 (NFE2). In some embodiments, the subject has a mutation in gene selected from the group consisting of VHL, EPO, EPOR, ELG1, EPAS1, HIF2A, and BPGM. In some embodiments, the subject has a high oxygen affinity variant selected from the group consisting of hemoglobin B (HBB) and hemoglobin A (HBA). Secondary polycythemia

Secondary polycythemia may result from functional hypoxia induced by lung disease, heart disease, increased altitude (hemoglobin increase of 4% for each 1000-m increase in altitude), congenital methemoglobinemia, and other high-oxygen affinity hemoglobinopathies stimulating increased EPO production. Secondary polycythemia may also result from increased EPO production secondary to benign and malignant EPO-secreting lesions. Secondary polycythemia may also be a benign familial polycythemia. In some embodiments, secondary polycythemia is due to genetic abnormalities. For instance, Chuvash polycythemia, a congenital polycythemia first recognized in an endemic Russian population, has mutations in the von Hippel-Lindau (VHL) gene, which is associated with a perturbed oxygen dependent regulation of EPO synthesis. Secondary polycythemia of the newborn is fairly common and may result from either chronic or acute fetal hypoxia or delayed cord clamping and stripping of the umbilical cord. Similar to primary polycythemia, secondary polycythemia is associated with many complications, including ischemic events in particular. Accordingly, GlyT1 inhibitors may be used in treating or reducing the risk of primary polycythemia, such as polycythemia vera, or secondary polycythemia.

In certain aspects, the disclosure relates to methods of treating secondary polycythemia in a subject, the method comprising administering to the subject a pharmaceutical composition comprising one or more glycine transporter inhibitor ( e.g ., a GlyT 1 inhibitor), or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor) or its salt. In some embodiments, the secondary polycythemia is associated with a disorder selected from the group consisting of hypoxia, central hypoxic process, lung disease, right-to-left cardiopulmonary vascular shunts (congenital or acquired), heart disease, heart failure, carbon monoxide poisoning, smoker’s erythrocytosis, high-altitude habitat, renal disease, kidney transplant, hemoglobinopathy with high-oxygen-affinity, decreased levels of erythrocyte 2,3,-DPG, bisphosphoglycerate mutase deficiency, methemoglobinemia, hereditary ATP increase, oxygen sensing pathway gene mutations, tumor, drug-induced secondary polycythemia, adrenal cortical hypersecretion, and idiopathic polycythemia. In some embodiments, the patient has an elevated erythropoietin (EPO) level. An elevated EPO level, usually as a secondary response to chronic hypoxemia, often leads to secondary polycythemia. In some embodiments, the elevated EPO level in the patient is in response to chronic hypoxemia. In some embodiments, the secondary polycythemia is associated chronic hypoxemia.

In some embodiments, the secondary polycythemia is associated with lung disease. In some embodiments, the lung disease is selected from the group consisting of chronic lung disease, interstitial lung disease, chronic obstructive pulmonary disease (COPD), Pickwickian syndrome, emphysema, pulmonary fibrosis, sleep apnea, hypoventilation syndromes, and obesity hypoventilation syndrome. In some embodiments, the secondary polycythemia associated with lung disease occurs as a result of functional hypoxia. In some embodiments, the secondary polycythemia associated with lung disease occurs as a result of chronic hypoxemia. In some embodiments, the secondary polycythemia is associated with heart disease. In some embodiments, the heart disease is selected from the group consisting of cyanotic heart disease and congenital heart disease. In some embodiments, the secondary polycythemia is associated with renal disease. In some embodiments, the renal disease is selected from the group consisting of local renal hypoxia, renal artery stenosis, cysts, polycystic kidney disease, hydronephrosis, nephrotic syndrome, diffuse parenchymal disease, Bartter’s syndrome, end-stage renal disease, long-term hemodialysis, and post-renal transplant erythrocytosis.

In some embodiments, the secondary polycythemia is associated with oxygen sensing pathway gene mutations. In some embodiments, the oxygen sensing pathway gene mutations are selected from the group consisting of EpoR, VHL, HIF2A, and PHD2. In some embodiments, the secondary polycythemia is associated with a tumor. In some embodiments, the tumor is a tumor with an excessive production of erythropoietin or erythropoietin related factors. In some embodiments, the tumor is selected from the group consisting of renal cell carcinoma, renal tumors, hepatocellular carcinoma, pheochromocytoma, cerebellar hemangioblastoma, uterine leiomyoma, ovarian carcinoma, meningioma, parathyroid carcinoma, and parathyroid adenoma. In some embodiments, the secondary polycythemia is drug-associated secondary polycythemia. In some embodiments, the drug-associated secondary polycythemia is selected from the group consisting of erythropoietin administration, androgen administration, anabolic steroid administration, synthetic testosterone administration, protein injections, gentamicin administration, and methyldopa administration. In some embodiments, the polycythemia is relative polycythemia. In some embodiments, the relative polycythemia is selected from the group consisting of Gaisbock’s syndrome, spurious polycythemia, or stress erythrocytosis. In some embodiments, the polycythemia is Chuvash polycythemia. C ₆ rtain primary treatment regimes may lead to an undesirably increase in red blood cells. For instance, the drugs gentamicin and methyldopa have been associated with increasing the number of red blood cells in a subject. Hence, the GlyT1 inhibitors may be used in conjunction or combination with one or more of gentamicin, methyldopa, or other drug that leads to increased production of red blood cells, mainly to off-set the undesired effects of producing too many red blood cells. In certain embodiments, by reducing their undesirable side effects, combination therapy with GlyT 1 inhibitors may allow the use of higher concentrations of gentamicin, methyldopa, or related drugs.

Accordingly, in certain embodiments, the GlyT1 inhibitors disclosed herein may be used to reduce erythropoiesis, and also to reduce the formation of erythroid progenitors, red blood cells, or both. In certain embodiments, methods of reducing erythropoiesis or red blood cell formation may be used to treat a subject that has or is at risk for having increased red blood cell count, increased hemoglobin levels, or increased total red blood cell volume, as described herein.

Therapies for polycythemia

A well-established hitherto existing method for treating polycythemia includes treatment using regularly scheduled phlebotomies (bloodletting). When first diagnosed, the phlebotomies are usually scheduled fairly frequent, e.g. multiple times per week, until RBC levels are brought to within normal range (e.g., hematocrit less than 45%), followed by phlebotomies which are then scheduled once a month or every other month depending upon the patient's rate of RBC formation. Because phlebotomy does not suppress the production of RBC ₈ in the bone marrow, the effect of each phlebotomy is transient, until patients become iron deficient.

Another approach to treating polycythemia attempts to reduce RBC formation by reducing the amount of available iron in the serum by increasing the removal of the iron from the body. Iron is an essential trace element for almost all organisms and is relevant in particular with respect to growth and the formation of blood. The balance of the iron metabolism is in this case primarily regulated on the level of iron recovery from hemoglobin of ageing erythrocytes and the duodenal absorption of dietary iron. The released iron is taken up via the intestine, in particular via specific transport systems (DMT-1, ferroportin), transferred into the blood circulation and thereby conveyed to the appropriate tissues and organs (transferrin, transferrin receptors).

In the human body, the element iron is of great importance, inter alia for oxygen transport, oxygen uptake, cell functions such as mitochondrial electron transport, cognitive functions, etc. and ultimately for the entire energy metabolism.

Iron uptake and storage is regulated by hepcidin. Hepcidin is produced in the liver and functions as the master iron regulatory hormone controlling intestinal iron uptake, and also regulates iron storage in other organs. Hepcidin limits iron-uptake by binding to the iron transport molecule ferroportin and causing its degradation. Hepcidin deficiency is a frequently found pathogenic feature in patients with iron overload.

One method for decreasing iron levels in a patient uses hepcidin agonists, such as hepcidin mimetics. It has been shown in animal models that high doses of hepcidin mimetics can ameliorate certain polycythemias, such as polycythemia vera, by diminishing erythropoiesis. However, over a dministration of hepcidin agonists can cause suppression of intestinal iron uptake and macrophage iron recycling, with potential exacerbation of suboptimal production of RBC ₈ , as in polycythemia vera. Additionally, hepcidin is limited in its use as a drug because of its complex structure which requires a complicated manufacturing, and also its limited in vivo duration of action.

Another method of decreasing iron levels in the patient includes the use of chelating agents. For example, deferoxamine (also known Desferal®), which is a bacterial siderophore, is an established drug used in chelation therapy. Deferoxamine binds iron in the bloodstream as an chelator and enhances its elimination via urine and feces. Two additional drugs, licensed for use in patients receiving regular blood transfusions, resulting in the development of iron overload, are deferasirox and deferiprone. The disadvantage in the treatment of decreasing iron levels using chelation therapy is that iron chelation therapies are known to exhibit a toxic potential. C ₆ rtain embodiments of the present disclosure relate to methods of administering a GlyT1 inhibitor disclosed herein to a subject in need thereof, wherein the subject has polycythemia. In some embodiments, GlyT1 inhibitors disclosed herein treat polycythemia while maintaining the subject’s iron levels. In some embodiments, GlyT1 inhibitors disclosed herein treat polycythemia while increasing the subject’s stored iron levels. In some embodiments, GlyT1 inhibitors disclosed herein treat polycythemia while decreasing the incidence of iron deficiency. In some embodiments, GlyT1 inhibitors disclosed herein reduce red blood cell synthesis while maintaining the subject’s iron levels. In some embodiments, GlyT 1 inhibitors disclosed herein reduce red blood cell synthesis while increasing the subject’s stored iron levels. In some embodiments, GlyT1 inhibitors disclosed herein reduce red blood cell synthesis while decreasing the incidence of iron deficiency. C ₆ rtain embodiments of the present disclosure relate to methods of administering a GlyT1 inhibitor disclosed herein to a subject in need thereof, wherein the subject has an iron deficiency associated with polycythemia. In some embodiments, the method decreases the incidence of iron deficiency by at least 10% ( e.g ., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method decreases the incidence of iron deficiency by at least 15%. In some embodiments, the method decreases the incidence of iron deficiency by at least 20%.

In some embodiments, the method decreases the incidence of iron deficiency by at least 25%. In some embodiments, the method decreases the incidence of iron deficiency by at least 30%. In some embodiments, the method decreases the incidence of iron deficiency by at least 35%. In some embodiments, the method decreases the incidence of iron deficiency by at least 40%. In some embodiments, the method decreases the incidence of iron deficiency by at least 45%. In some embodiments, the method decreases the incidence of iron deficiency by at least 50%. In some embodiments, the method decreases the incidence of iron deficiency by at least 55%. In some embodiments, the method decreases the incidence of iron deficiency by at least 60%. In some embodiments, the method decreases the incidence of iron deficiency by at least 65%. In some embodiments, the method decreases the incidence of iron deficiency by at least 70%. In some embodiments, the method decreases the incidence of iron deficiency by at least 75%. In some embodiments, the method decreases the incidence of iron deficiency by at least 80%. In some embodiments, the method decreases the incidence of iron deficiency by at least 85%.

In some embodiments, the method decreases the incidence of iron deficiency by at least 90%. In some embodiments, the method decreases the incidence of iron deficiency by at least 95%. In some embodiments, the method decreases the incidence of iron deficiency by at least 100%.

In some embodiments, the method further improves iron deficiency in the subject. In some embodiments, the method improves iron deficiency in the subject by at least 10% ( e.g ., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method improves iron deficiency in the subject by at least 15%. In some embodiments, the method improves iron deficiency in the subject by at least 20%. In some embodiments, the method improves iron deficiency in the subject by at least 25%. In some embodiments, the method improves iron deficiency in the subject by at least 30%. In some embodiments, the method improves iron deficiency in the subject by at least 35%. In some embodiments, the method improves iron deficiency in the subject by at least 40%. In some embodiments, the method improves iron deficiency in the subject by at least 45%. In some embodiments, the method improves iron deficiency in the subject by at least 50%. In some embodiments, the method improves iron deficiency in the subject by at least 55%. In some embodiments, the method improves iron deficiency in the subject by at least 60%. In some embodiments, the method improves iron deficiency in the subject by at least 65%. In some embodiments, the method improves iron deficiency in the subject by at least 70%. In some embodiments, the method improves iron deficiency in the subject by at least 75%. In some embodiments, the method improves iron deficiency in the subject by at least 80%. In some embodiments, the method improves iron deficiency in the subject by at least 85%. In some embodiments, the method improves iron deficiency in the subject by at least 90%. In some embodiments, the method improves iron deficiency in the subject by at least 95%. In some embodiments, the method improves iron deficiency in the subject by at least 100%.

Erythropoiesis

Erythropoiesis refers generally to the process by which red blood cells (erythrocytes) are produced from HSC ₈ , and includes the formation of erythroid progenitor cells. Erythropoiesis is a carefully ordered sequence of events. Initially occurring in fetal hepatocytes, the process is taken over by the bone marrow in the child and adult. Although multiple cytokines and growth factors are dedicated to the proliferation of the red blood cell, the primary regulator is erythropoietin (EPO). Red blood cell development is initially regulated by stem cell factor (SCF), which commits hematopoietic stem cells to develop into erythroid progenitors. Subsequently, EPO continues to stimulate the development and terminal differentiation of these progenitors. In the fetus, EPO is produced by monocytes and macrophages found in the liver. After birth, EPO is produced in the kidneys; however, Epo messenger RNA (mRNA) and EPO protein are also found in the brain and in red blood cells (RBC ₈ ), suggesting the presence of paracrine and autocrine functions.

Erythropoiesis escalates as increased expression of the EPO gene produces higher levels of circulating EPO. EPO gene expression is known to be affected by multiple factors, including hypoxemia, transition metals (Co2+, Ni2+, Mn2+), and iron chelators. However, the major influence is hypoxia, including factors of decreased oxygen tension, red blood cell loss, and increased oxygen affinity of hemoglobin. For instance, EPO production may increase as much as 1000-fold in severe hypoxia.

Erythropoiesis requires the proper biosynthesis of heme and as erythroblasts mature, their demand for heme and iron dramatically increase. Erythroid cells synthesize large amounts of heme and hemoglobin while simultaneously absorbing lots of iron into the cell. Glycine is one of the key initial substrates for heme and globin synthesis. As such, decreased levels of glycine due to GlyT1 inhibition could lead to a decrease in heme synthesis. In certain aspects, the disclosure relates to methods of inhibiting heme synthesis in a subject with polycythemia, comprising administering to a subject a pharmaceutical composition comprising one or more glycine transporter inhibitor ( e.g . , a GlyT 1 inhibitor), or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor) or its salt. In some embodiments, the heme synthesis is inhibited in a dose dependent manner.

In some embodiments, the GlyT 1 inhibitors disclosed herein reduce red blood cell synthesis (also known as erythropoiesis), and may be used to treat a condition associated with increased red blood cells. In some embodiments, the GlyT1 inhibitors disclosed herein may modulate red blood cell synthesis by reducing the formation of heme. In some embodiments, the disclosure relates to methods of inhibiting red blood cell synthesis in a subject with polycythemia, comprising administering to a subject a pharmaceutical composition comprising one or more glycine transporter inhibitor (e.g. , a GlyT 1 inhibitor), or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor ( e.g ., a GlyT1 inhibitor) or its salt. In some embodiments, the red blood cell synthesis is inhibited in a dose dependent manner. In some embodiments, the disclosure relates to methods of decreasing the red blood cell count in a subject with polycythemia, comprising administering to a subject a pharmaceutical composition comprising one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor), or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor (e.g. , a GlyT 1 inhibitor) or its salt. In some embodiments, the red blood cell count is decreased in a dose dependent manner. In some embodiments, merely by way of non- limiting example, GlyT1 inhibitors may be administered directly to a subject to reduce red blood count, if desired. In this regard, a normal red blood cell count typically ranges from about 4.7 to about 6.1 million red blood cells per mΐ in men, and about 4.2 to about 5.4 million red blood cells per mΐ in women. A high red blood cell count is generally defined as more than about 5.3 million red blood cells per mΐ of blood for men and about 5.1 million red blood cells per mΐ of blood for women. In children, the threshold for high red blood cell count varies with age and sex. Red blood count may also be reflected by a person's hematocrit (i.e., packed cell volume (PCV) or erythrocyte volume fraction (EVF)), which is the proportion or percentage of blood volume that is occupied by red blood cells. A normal hematocrit is normally about 49% for men and about 48% for women. A higher hematocrit value indicates a greater number of red blood cells. In severe cases, a high red blood cell count can impair circulation and lead to abnormal clotting, among other problems.

In some embodiments, the GlyT 1 inhibitors disclosed herein reduce hemoglobin synthesis in a subject with polycythemia, and may be used to treat a condition associated with increased red blood cells. In some embodiments, the GlyT1 inhibitors disclosed herein may modulate hemoglobin synthesis by reducing the formation of heme. In some embodiments, the disclosure relates to methods of inhibiting hemoglobin synthesis in a subject with polycythemia, comprising administering to a subject a pharmaceutical composition comprising one or more glycine transporter inhibitor (e.g. , a GlyT 1 inhibitor), or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor) or its salt. In some embodiments, the hemoglobin synthesis is inhibited in a dose dependent manner. Red blood cell count and hematocrit Certain embodiments of the present disclosure relate to methods of administering a GlyT1 inhibitor disclosed herein to a subject in need thereof, wherein the subject has an increased red blood cell count ( e.g ., greater than about 5.3 million red blood cells per mΐ of blood for men and about 5.1 million red blood cells per mΐ of blood for women, often by a clinically or statistically significant amount), or an increased hematocrit (e.g., greater than about 49% for men or about 48% for women, often by a clinically or statistically significant amount). In some embodiments, the subject has hematocrit levels that are at least 48%. In some embodiments, the subject has hematocrit levels that are at least 49%.

In some embodiments, the subject’s hematocrit levels are at least 10%, 20%, 30%, 40%, or 50% more than hematocrit levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject’s hematocrit levels are at least 10% more than hematocrit levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject’s hematocrit levels are at least 20% more than hematocrit levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject’s hematocrit levels are at least 30% more than hematocrit levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject’s hematocrit levels are at least 40% more than hematocrit levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject’s hematocrit levels are at least 50% more than hematocrit levels in a healthy subject prior to administration of the GlyT 1 inhibitor.

In some embodiments, the subject has a red blood cell count that is at least 10%, 20%, 30%, 40%, or 50% more than a red blood cell count in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has a red blood cell count that is at least 10% more than a red blood cell count in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has a red blood cell count that is at least 20% more than a red blood cell count in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has a red blood cell count that is at least 30% more than a red blood cell count in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has a red blood cell count that is at least 40% more than a red blood cell count in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has a red blood cell count that is at least 50% more than a red blood cell count in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has a red blood cell count greater than 5.1 x 10 ¹² /L. In some embodiments, the subject has a red blood cell count greater than 5.3 x 10 ¹² /L.

In certain embodiments, administration of a GlyT 1 inhibitor (e.g. , bitopertin) to such a subject reduces their red blood cell count or hematocrit. Also included are methods of reducing red blood cells in a subject, and methods of reducing hematocrit in a subject, including a subject that has a higher than normal red blood cell count or hematocrit, or is at risk for developing such a condition, comprising administering to the subject a GlyT1 inhibitor (e.g., bitopertin) of the present disclosure, and thereby reducing red blood cell count or hematocrit in the subject.

In some embodiments, the method decreases the subject’s red blood cell levels by at least 10% (e.g, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method decreases the subject’s red blood cell levels by at least 15%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 20%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 25%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 30%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 35%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 40%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 45%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 50%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 55%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 60%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 65%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 70%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 75%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 80%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 85%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 90%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 95%. In some embodiments, the method decreases the subject’s red blood cell levels by at least 100%.

In some embodiments, the method decreases the subject’s hematocrit levels by at least 10% (e.g, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method decreases the subject’s hematocrit levels by at least 15%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 20%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 25%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 30%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 35%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 40%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 45%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 50%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 55%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 60%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 65%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 70%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 75%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 80%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 85%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 90%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 95%. In some embodiments, the method decreases the subject’s hematocrit levels by at least 100%. In some embodiments, the method decreases the subject’s hematocrit levels to less than 48%.

There are many general diseases or conditions that increase the red blood cell count or hematocrit of a subject, and which may be improved or treated by the GlyT1 inhibitors disclosed herein. As one general, illustrative example, high red blood cell count may result from increases in red blood cell production, mainly to compensate for low oxygen levels, which may be caused by poor heart or lung function. Also, high red blood cell count may result from increased release of erythropoietin (EPO) from the kidneys (EPO enhances red blood cell production), production of too many red blood cells by the bone marrow, impairment of the oxygen-carrying capacity of red blood cells (leading to over-production), compensation for a limited oxygen supply in higher altitudes, and the loss of blood plasma (i.e ., the liquid component of blood), which may create relatively high levels of red blood cells, volume-wise.

Further examples of conditions that are associated with high red blood cell count include, without limitation, living at a high altitude, smoking, congenital heart disease, failure of the right side of the heart (i.e., cor pulmonale), scarring and thickening of the lung tissuei.e ., pulmonary fibrosis), bone marrow disorders (e.g., polycythemia vera), dehydration, such as from severe diarrhea or excessive sweating, kidney disease/cancer, exposure to carbon monoxide, anabolic steroid use, COPD or other lung diseases, such as pulmonary fibrosis, and EPO doping, mainly to enhance athletic performance. Hence, the GlyT 1 inhibitors disclosed herein can be used to treat or reduce the risk of developing high red blood cell count or volume as it is associated with these or any other conditions known in the art.

Accordingly, in certain embodiments, GlyT 1 inhibitors may be used to reduce erythropoiesis, and also to reduce the formation of red blood cells. In certain embodiments, methods of reducing erythropoiesis or red blood cell formation may be used to treat a subject that has or is at risk for having increased red blood cell count, increased hemoglobin levels, or increased total red blood cell volume, as described herein and known in the art.

Red blood cell mass and hemoglobin

In certain embodiments, the present disclosure relates to methods of administering a GlyT1 inhibitor disclosed herein to a subject in need thereof, wherein the subject has an increased red blood cell mass (e.g., more than 25% above mean normal predicted value, often by a clinically or statistically significant amount), or increased hemoglobin levels (e.g., greater than about 16.5 g/dL for men or about 16.0 g/dL for women, often by a clinically or statistically significant amount).

In some embodiments, the subject has red blood cell mass levels that are at least 10%, 20%, 30%, 40%, or 50% more than red blood cell mass levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has red blood cell mass levels that are at least 10% more than red blood cell mass levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has red blood cell mass levels that are at least 20% more than red blood cell mass levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has red blood cell mass levels that are at least 30% more than red blood cell mass levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has red blood cell mass levels that are at least 40% more than red blood cell mass levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has red blood cell mass levels that are at least 50% more than red blood cell mass levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has red blood cell mass levels that are at least 25% above mean normal predicted value.

In some embodiments, the subject has hemoglobin levels that are at least 10%, 20%, 30%, 40%, 50%, or 60% more than hemoglobin levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has hemoglobin levels that are at least 10% more than hemoglobin levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has hemoglobin levels that are at least 20% more than hemoglobin levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has hemoglobin levels that are at least 30% more than hemoglobin levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has hemoglobin levels that are at least 40% more than hemoglobin levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has hemoglobin levels that are at least 50% more than hemoglobin levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has hemoglobin levels that are at least 60% more than hemoglobin levels in a healthy subject prior to administration of the GlyT1 inhibitor. In some embodiments, the subject has hemoglobin levels that are greater than 16.0 g/dL. In some embodiments, the subject has hemoglobin levels that are greater than 16.5 g/dL.

In certain embodiments, administration of a GlyT 1 inhibitor (e.g. , bitopertin) to such a subject reduces their red blood cell mass or hemoglobin levels. Also included are methods of reducing red blood cells mass in a subject, and methods of reducing hemoglobin levels in a subject, including a subject that has a higher than normal red blood cell mass or hemoglobin levels, or is at risk for developing such a condition, comprising administering to the subject a GlyT1 inhibitor ( e.g ., bitopertin) of the present disclosure, and thereby reducing red blood cell mass or hemoglobin levels in the subject.

In some embodiments, the method decreases the subject’s red blood cell mass by at least 10% (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method decreases the subject’s red blood cell mass by at least 15%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 20%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 25%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 30%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 35%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 40%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 45%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 50%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 55%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 60%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 65%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 70%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 75%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 80%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 85%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 90%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 95%. In some embodiments, the method decreases the subject’s red blood cell mass by at least 100%.

In some embodiments, the method decreases the subject’s hemoglobin levels by at least 10% (e.g, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method decreases the subject’s hemoglobin levels by at least 15%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 20%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 25%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 30%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 35%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 40%.

In some embodiments, the method decreases the subject’s hemoglobin levels by at least 45%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 50%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 55%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 60%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 65%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 70%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 75%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 80%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 85%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 90%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 95%. In some embodiments, the method decreases the subject’s hemoglobin levels by at least 100%. In some embodiments, the method decreases the subject’s hemoglobin levels to less than 16 g/dL. In some embodiments, the method decreases the subject’s hemoglobin levels to less than 16.5 g/dL.

Complications of polycythemia

In certain aspects, the disclosure relates to methods of preventing, treating, or reducing the progression rate and/or severity of one or more complications of polycythemia in a subject, the method comprising administering to the subject a pharmaceutical composition comprising one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor), or a pharmaceutically acceptable salt thereof, or a prodrug of the one or more glycine transporter inhibitor (e.g., a GlyT1 inhibitor) or its salt. In some embodiments, the one or more complications of polycythemia is a thromboembolic event. In some embodiments, the method reduces the risk of thromboembolic events. In some embodiments, the thromboembolic event is arterial thrombosis. In some embodiments, the thromboembolic event is venous thrombosis. In some embodiments, the one or more complications of polycythemia is blurred vision. In some embodiments, the method reduces the risk of blurred vision by at least 10% (e.g, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%,

65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the one or more complications of polycythemia is a headache. In some embodiments, the method reduces the risk of headaches by at least 10% ( e.g ., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%).

In some embodiments, the one or more complications of polycythemia is selected from the group consisting of: pulmonary embolisms, transient ischemic attacks, transient visual defects, deep vein thrombosis, splenomegaly, hepatomegaly, myelofibrosis, and acute myeloid leukemia. In some embodiments, the myelofibrosis is selected from the group consisting of low-risk myelofibrosis, intermediate-risk myelofibrosis, high-risk myelofibrosis, primary myelofibrosis, post-essential thrombocythemia myelofibrosis, and post-polycythemia vera myelofibrosis.

Combination Therapies C ₆ rtain embodiments may include combination therapies for treating polycythemias, including the administration of one or more GlyT 1 inhibitors disclosed herein, in combination with other polycythemia-based therapeutic agents or treatment modalities. Examples of combination therapies included, without limitation, any one or more additional active agents and/or supportive therapies selected from the group consisting of: Hydroxyruea (e.g., Droxia®, Hydrea®), Interferon alpha, Interferon alpha-2b (e.g., Intron® A), Ruxolitinib (e.g., Jalcafi®), Busulfan (e.g., Busulfex®, Myleran®), radiation treatment, hepcidin mimetics (e.g., PTG-300), matriptase-2 inhibitors, ferroportin inhibitors, JAK inhibitors, BET inhibitors, MDM2 inhibitors, and HDAC inhibitors.

Common therapies for high-risk polycythemia vera patients includes hydroxyurea or interferon. Hydroxyurea is a chemotherapeutic agent that can be used for decades, though some studies suggest that it may increase the risk of PV transforming into acute myeloid leukemia. Additionally, many patients do not respond well to or are intolerant of hydroxyurea (mucocutaneous ulcers are the leading toxicity), and require a different therapy. In some embodiments, the GlyT1 inhibitors disclosed herein are useful in treating a subject who has an inadequate response or a subject who is intolerant to hydroxyurea. In some embodiments, the subject has an inadequate response to hydroxyurea. In some embodiments, the subject is intolerant to hydroxyurea.

Another well-established method for treating polycythemia includes treatment using regularly scheduled phlebotomies (bloodletting). In some embodiments, the GlyT1 inhibitors disclosed herein are useful in treating a subject who has polycythemia requiring therapeutic phlebotomies. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 10% ( e.g ., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or at least 100%). In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 15%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 20%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 25%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 30%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 35%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 40%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 45%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 50%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 55%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 60%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 65%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 70%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 75%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 80%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 85%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 90%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 95%. In some embodiments, the method reduces the patient’s need for therapeutic phlebotomies by at least 100%. In some embodiments, the method eliminates the patient’s need for therapeutic phlebotomies.

Quality of Life

In certain aspects, the disclosure relates to methods of preventing, treating, or reducing the progression rate and/or severity of polycythemia (e.g., treating, preventing, or reducing the progression rate and/or severity of one or more complications of polycythemia) comprising administering to a patient in need thereof an effective amount of a GlyT 1 inhibitor ( e.g ., bitopertin), wherein the method increases the patient’s quality of life by at least 1% (e.g., 1%, 2%, 3%, 4%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%). In some embodiments, the method relates to increasing the patient’s quality of life by at least 1%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 2%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 3%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 4%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 5%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 10%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 15%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 20%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 25%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 30%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 35%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 40%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 45%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 50%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 55%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 60%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 65%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 70%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 75%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 80%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 85%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 90%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 95%. In some embodiments, the method relates to increasing the patient’s quality of life by at least 100%. In some embodiments, the patient’s quality of life is measured using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30). In some embodiments, the patient’s quality of life is measured using the Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF). In some embodiments, the patient’s quality of life is measured using the Pruritus Symptom Impact Scale (PSIS). In some embodiments, the patient’s quality of life is measured using the Patient Global Impression of Change (PGIC).

EXEMPLIFICATION

The invention now being generally described, it will be more readily understood by reference to the following examples, which are included merely for purposes of illustration of certain embodiments of the present invention, and are not intended to limit the invention.

Example 1: Synthesis of Compounds

The compounds disclosed herein can be made in accordance with well known procedures and by processes known and disclosed in the art. For example, compounds of Formula I, such as bitopertin, can be prepared in accordance with the synthetic protocols provided inU.S. Patent Nos. 7,319,099, 9,877,963, and 7,812,161, the contents of which are hereby incorporated by reference in their entirety. In addition, compounds of Formula II, such as PF-3463275, can be prepared in accordance with the synthetic protocols provided in U.S. Patent No. 8,124,639, the contents of which are hereby incorporated by reference in its entirety.

Example 2: Effect of GlyT1 inhibitor in Erythropoietin (EPO)-induced secondary ervthrocvtosis murine model

The EPO-induced secondary erythrocytosis model was used to evaluate the in vivo pharmacodynamic effect of GlyT 1 inhibitor in preventing, treating, or reducing the progression rate and/or severity of polycythemia vera. Erythropoietin (EPO) stimulates the production of red blood cells and results in increased hematocrit in mice after daily dosing for 7 days at 50 IU. Therefore, the EPO model mimics the hematological parameters of polycythemia vera where JAK2 mutation drives the erythrocytosis. Briefly, 30 mg/kg of GlyT 1 inhibitor bitopertin or vehicle control was administrated orally into wildtype C57BL/6J mice (10 mice per group) once daily from day 1 to day 15. 50 IU EPO was administrated daily by intraperitoneal route from day 8 to day 14 to induce erythrocytosis resembling the pathological process of polycythemia vera (Figure 1A). Blood samples were collected from submaxillary on day 8 before the first EPO administration and on day 15, 6 hours after the last dose of GlyT 1 inhibitor for CBC panel analysis using Sysmex XN- 1000TM hematology analyzer. Bioanalysis of drug concentration was performed in plasma collected 6 hours after the last dose. All mice were weighed and humanely euthanized. The spleen was weighed and the spleen index was calculated via dividing the weight of spleen by the whole-body weight.

No major body -weight changes were observed with GlyT1 inhibitor treatment over the 14-day treatment (Figure IB). The average plasma drug concentration 6 hours after the last dose was 639 ± 38 ng/mL in mice dosed with 30mg/kg GlyT1 inhibitor (Figure 1C).

The spleen index increased from 0.39% in normal mice to 1.56% in mice administrated with EPO and vehicle. Treatment of 30 mg/kg GlyT1 inhibitor reduced the spleen index to 1.26% (Figure ID). Consistently, treatment of GlyT1 inhibitor reduced hematocrit (HCT%), RBC count and Hemoglobin levels (Figure IE; Figure IF; and Figure 1G), suggesting inhibiting GlyT1 is a potential therapeutic approach to treat polycythemia vera.

Example 3: Effect of GlyT1 inhibitor in Darbepoietin-alpha (DPO)-induced secondary erythrocytosis murine model

Darbepoietin-alpha (DPO) is a long-lasting analogue of EPO. To investigate the in vivo pharmacodynamic effect of GlyT1 inhibitor in preventing, treating, or reducing the progression rate and/or severity of polycythemia vera for longer periods, DPO was used to stimulate the production of red blood cells and mimicking the hematological features of polycythemia vera where JAK2 mutation drives the erythrocytosis.

Briefly, C57BL/6J mice were administrated with DPO subcutaneously at 10 μg/kg/week for 2 weeks to induce erythrocytosis resembling the pathological process of polycythemia vera (Figure 2A). 30 mg/kg or 60 mg/kg of GlyT1 inhibitor bitopertin or vehicle control was administrated orally into wild type C57BL/6J mice (10 mice per group for the vehicle and 30 mg/kg groups; 15 mice for the 60 mg/kg group) once daily from day 7 to day 15. The 60mg/kg group was dosed at 20mg/kg on day 7, 40mg/kg on day 8 - 9, 50mg/kg on day 10-11, 60mg/kg on day 12-15. Blood samples were collected from submaxillary on day 0 before the first DPO administration, on day 7 before the first dose of GlyT1 inhibitor, and on day 15, 6 hours after the dosing of GlyT1 inhibitor for CBC panel analysis using Sysmex XN-1000TM hematology analyzer.

No major body-weight changes were observed with bitopertin over the 8-day treatment duration (Fig. 2B). Bitopertin reduced hematocrit (HCT%), RBC count and Flemoglobin levels (HGB) in a dose dependent manner (Fig. 2C, D, E). A significant reduction of reticulocyte hemoglobin (RET-He) and mean corpuscular hemoglobin (MCHI) were observed with the treatment of GlyT1 inhibitor (Fig. 2F, G), suggesting bitopertin treatment reduced the hemoglobin levels in red blood cell precursors. The treatment slightly reduced the mean corpuscular volume (MCV) (Fig. 2H). The study confirmed the effect of Bitopertin in reducing hemoglobin in red blood cell precursors and hematocrit in the DPO- induced secondary erythrocytosis model, suggesting inhibition of GlyT 1 may be a potential therapeutic approach to treat polycythemia vera.

Example 4: Effect of GlyT1 inhibitor in Jak2V617F bone marrow transplantation mouse model

The effects of a GlyT1 inhibitor are examined in a polycythemia vera mouse model comprising a Jak2-V617F mutation in the bone marrow cells to evaluate the effects of the GlyT 1 inhibitor versus placebo for the treatment of polycythemia vera.

The activating mutations of Janus kinase 2 (e.g., Jak2-V617F) are present in approximately 95% of all polycythemia vera patients. Increased hematocrit, hemoglobin concentration, red cell counts, and splenomegaly are salient clinical features of this disease.

Inhibition of glycine uptake using GlyT1 inhibitor bitopertin may alleviate disease symptoms of PV patients by restricting heme synthesis in erythroid cells and inhibiting erythroid cell expansion and splenomegaly. This study evaluates the effect of bitopertin on reducing disease symptoms in the bone marrow transplantation mouse model of PV.

Experimental Design Male BALB/c mice between 4-8 weeks old may be used for the experiment. Bone marrow stem progenitor lineage negative, c-Kit positive (hereafter, referred to as LK cells) cells will be isolated from BALB/c mice. Isolated LK cells will then be transduced with lentiviral vector coding Jak2 gene carrying the V617F mutation (Jak2V617F) or wildtype Jak2 (Jak2WT) or empty vector control, together with GFP expression from the same lentiviral construct. Approximately 5x10 ⁵ or lxlO ⁶ of the transduced LK cells will be transplanted into irradiated (2 doses of 450 rads) BALB/c recipient mice (Figure 3A). Transplantation of Jak2V617F overexpressing bone marrow cells into conditioned syngenic recipient mice will faithfully recapitulate PV-like disease with peripheral hematocrit increases by 15-18 days post-transplantation.

Three weeks after the bone marrow transplantation procedure, blood will be taken from the recipient mice and used to determine the level of bone marrow engraftment as determined by percent of GFP positive cells in peripheral blood. The mice will be allocated into a total of 10 treatment groups as outlined below:

During the next four weeks, mice in the treatment groups will receive daily oral dosing of vehicle, or bitopertin at 30 mg/kg or 60 mg/kg. Blood will be collected at day -1, end of week 2 and end of week 4. All groups will be monitored for PV symptoms and level of engraftment through the peripheral blood by performing CBC analysis (hematocrit, hemoglobin, serum iron, red cell and platelet counts) and GFP expression. GFP expression may be measured using flow cytometry. At the end of the study, mice will be humanely euthanized and spleen and bone marrow pathology will be analyzed. The erythroid colony output of bone marrow cells in colony assays from all treatment groups will be measured (Figure 3B). It is predicted that bitopertin will reduce hematocrit as well as other PV symptoms such as splenomegaly, RBC counts, MCV and hemoglobin after 4-weeks of dosing in the bone marrow transplantation PV mouse model.

INCORPORATION BY REFERENCE

All publications and patents mentioned herein are hereby incorporated by reference in their entirety as if each individual publication or patent was specifically and individually indicated to be incorporated by reference. While specific embodiments of the subject matter have been discussed, the above specification is illustrative and not restrictive. Many variations will become apparent to those skilled in the art upon review of this specification and the claims below. The full scope of the invention should be determined by reference to the claims, along with their full scope of equivalents, and the specification, along with such variations.