Methods of treating fragile x syndrome using PDE4 inhibitors

Abstract

The present disclosure relates to methods of treating fragile X syndrome (or related symptoms or conditions) using 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof; corresponding doses and dosing schedules; and compositions for use therein.

Description

Attorney Docket No: 254409.000968 PATENTMethods of Treating Fragile X Syndrome Using PDE4 InhibitorsCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Provisional Application Nos. 63 / 879,237 (filed September 10, 2025) and 63 / 718,907 (filed November 11, 2024), the disclosures of which are herein incorporated by reference in their entireties.FIELD

[0002] The present disclosure relates to methods of treating fragile X syndrome (or related symptoms or conditions) using PDE4 inhibitors, including doses, dosing schedules, and compositions for use therein.BACKGROUND

[0003] Fragile X syndrome (FXS) is a genetic disorder caused by a repeat expansion of the fragile X messenger ribonucleoprotein 1 (FMRI) gene, leading to transcriptional silencing and loss of expression of the associated protein, fragile X messenger ribonucleoprotein (FMRP). FXS is one of the most common forms of inherited intellectual disability and is associated with a range of developmental issues, including cognitive dysfunction, anxiety, and social and behavioral challenges. FXS is the most common inherited cause of intellectual disability and autism spectrum disorders. Individuals with FXS often exhibit a range of cognitive, behavioral, and physical symptoms, including learning disabilities, social anxiety, hyperactivity, and distinctive facial features.

[0004] The diagnosis of FXS can often be delayed due to the variability in symptom presentation and the overlap with other developmental disorders.

[0005] Current treatments for FXS are limited and primarily focus on managing symptoms. Behavioral therapies, educational interventions, and medications such as stimulants, antidepressants, and antipsychotics are commonly used to alleviate specific symptoms. However, 1321886535vlAttorney Docket No: 254409.000968 PATENT these treatments do not target the core deficits associated with FXS. and their effectiveness can vary widely among individuals.

[0006] This underscores the urgent need for the development of new therapeutic approaches, such as the use of phosphodiesterase-4 (PDE4) inhibitors, which have shown promise in their potential to improve cognitive function and reduce behavioral symptoms in FXS patients. PDE4 inhibitors can block the PDE4 enzyme, which is widely expressed throughout the body and breaks down cyclic adenosine monophosphate (cAMP), a second messenger involved in many biological processes. By increasing cAMP levels within neurons (which is decreased in individuals with FXS), PDE4 inhibitors can enhance neural signaling pathways and promote plasticity. Despite their potential, challenges, such as dose-limiting side effects, remain and limit optimal efficacy and safety of PDE4 inhibitors. There are unmet needs to develop PDE4 inhibitors that are both effective and well-tolerated to provide a viable treatment option for individuals with FXS.SUMMARY

[0007] Provided herein is a method of treating FXS, comprising administering to a subject in need thereof a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0008] Further provided herein is a method of treating, reducing, or ameliorating one or more of developmental delays, intellectual and developmental disabilities (IDD), intellectual deficits, learning disabilities, anxiety, depression, obsessive-compulsive behaviors, attentiondeficit disorder (ADD), hyperactivity disorder, aberrant behavior, social and communication deficits, autism spectrum disorder, seizures, insomnia, obesity, and hypotonia in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.2321886535vlAttorney Docket No: 254409.000968 PATENT

[0009] Also provided herein is a method of treating, reducing, or ameliorating developmental delays in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0010] Additionally provided herein is a method of treating, reducing, or ameliorating IDD, intellectual deficits, or learning disabilities in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0011] Additionally provided herein is a method of treating, reducing, or ameliorating anxiety, depression, or obsessive-compulsive behaviors in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof.

[0012] Additionally provided herein is a method of treating, reducing, or ameliorating ADD, hyperactivity disorder, autism spectrum disorder, aberrant behavior, or social and communication deficits in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0013] Additionally provided herein is a method of treating, reducing, or ameliorating seizures, insomnia, obesity, or hypotonia in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0014] Additionally provided herein is a method of treating fragile X-associated Tremor / Ataxia syndrome (FXTAS) comprising administering to a subject in need thereof a therapeutically effective amount of 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0015] Additionally provided herein is a method of improving cognitive abilities in a subject having FXS comprising administering to the subject a therapeutically effective amount of3321886535vlAttorney Docket No: 254409.000968 PATENT5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0016] Any of these methods can further be used in combination with a training protocol, as described further herein.

[0017] Additionally provided herein is a pharmaceutical composition (and corresponding kits) for use in any of the methods, as described further herein, including compositions comprising about 0.1 mg to about 5 mg of 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof; and a pharmaceutically acceptable earner.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 shows, in an object location test, a discrimination index (DI) graph for MRM- 3379 administered and tested at doses of 0.01, 0.03, 0.1, and 0.3 mg / kg (the control of placebo was represented at 0.0 mg / kg), and the post-dose brain and plasma concentrations.

[0019] Figure 2 shows, in an object location test, DI graphs as a function of the brain and plasma concentration of MRM-3379 (0.03, 0.1, and 0.3 mg / kg) relative to zatolmilast (BPN14770) (0.01, 0.03, 0.1, 0.3, 1, and 3 mg / kg).

[0020] Figure 3 shows, in an object location test, the plasma concentration (CP) and the brain concentration (Cb) of MRM-3379 at 0.3 mg / kg as a function of the time duration after administration.

[0021] Figure 4A shows the brain-to-plasma concentration ratio for MRM-3379, BPN14770, and roflumilast for rats, mice, and primates.

[0022] Figure 4B shows a comparison of the emetic window for MRM-3379 and roflumilast.

[0023] Figure 4C shows concentration response curves for TNFa and CXCL10 in a study on suppression of cytokine responses.

[0024] Figure 5 shows the effects of MRM-3379 on scopolamine-induced object recognition memory impairment using a 1-hour inter-trial interval (ITI).4321886535vlAttorney Docket No: 254409.000968 PATENT

[0025] Figure 6 shows, in a novel object recognition test, a DI graph as a function of doses (a single oral dose at each level). 15m Veh stands for vehicle-treated mice that received the maximal training (15 minutes). MRM-3379 treated mice received 3 minutes of training.

[0026] Figure 7 shows, in a novel object recognition test, a DI graph as a function of doses administered once daily for 4 days. “15min” stands for vehicle-treated mice that received the maximal training (15 minutes). MRM-3379 treated mice received 3 minutes of training.

[0027] Figure 8 shows, in a contextual fear conditioning test, the amount of freezing behavior observed during the test period for foot shocked rats.

[0028] Figure 9 shows a linear plot of arithmetic mean MRM-3379 plasma concentrations versus nominal time post dose by study part and treatment (primary pharmacokinetic population) in human subjects. The “fed” dose was administered with food.

[0029] Figure 10 shows a linear plot of arithmetic mean MRM-3379 plasma concentrations following single oral doses of MRM-3379 to human subjects in the fed and fasted states.

[0030] Figure 11 shows a linear plot of arithmetic mean MRM-3379 plasma concentrations following single oral doses of MRM-3379 in healthy elderly subjects.

[0031] Figure 12 shows a linear plot of arithmetic mean MRM-3379 plasma concentrations following single oral doses of MRM-3379 in healthy non-elderly adults.

[0032] Figure 13 shows the presence of MRM-3379 in cerebrospinal fluid after multiple dose administration in healthy non-elderly adult subjects.

[0033] Figure 14 provides the % PDE4 occupancy values versus either the plasma C max (top panel) or plasma AUC (lower panel) of MRM-3379 for individual subjects.

[0034] Figure 15A provides results of an open field test (distance travelled) based on a FXS mouse model in Trial 1.

[0035] Figure 15B provides results of an open field test (distance travelled) based on a FXS mouse model in Trial 2.

[0036] Figure 15C provides results of a nesting test based on a FXS mouse model in Trial 1.

[0037] Figure 15D provides results of a nesting test based on a FXS mouse model in Trial 2.5321886535vlAttorney Docket No: 254409.000968 PATENT

[0038] Figure 15E provides results of a marble burying test based on a FXS mouse model in Trial 1.

[0039] Figure 15F provides results of a marble burying test based on a FXS mouse model in Trial 2.

[0040] Figure 15G provides results of a social interaction test based on a FXS mouse model in Trial 1.

[0041] Figure 15H provides results of a social interaction test based on a FXS mouse model in Trial 2.

[0042] Figure 16 shows dissolution profiles of MRM-3379 capsules comprising 0.25 mg drug substance (DS).

[0043] Figure 17 shows dissolution profiles of MRM-3379 capsules comprising 25 mg drug substance (DS).

[0044] Figure 18 shows dissolution profiles of MRM-3379 capsules comprising 0.25 mg, 2.5 mg, and 25 mg drag substance (DS).DETAILED DESCRIPTION

[0045] 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.

[0046] As used herein, “5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2- amine” has a chemical structure of:6321886535vlAttorney Docket No: 254409.000968 PATENT1628114-10-2). In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine is referred to as MRM-3379, ENT-3379, or DNS-3379.

[0047] As used herein, the terms “a” or “an” means “at least one” or “one or more” unless the context clearly indicates otherwise.

[0048] 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.

[0049] As used herein, the term “alkyl” means a saturated hydrocarbon group that 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-l -propyl, 2-methyl-2-propyl, 2- methyl-1 -butyl, 3-methyl-l -butyl, 2-methyl-3-butyl, 2-methyl-l -pentyl, 2,2-dimethyl-l -propyl, 3-methyl-l -pentyl. 4-methyl-l -pentyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl. 4-methyl-2-pentyl. 2,2-dimethyl-l -butyl, 3,3-dimethyl-l-butyl, 2-ethyl-l -butyl, and the like.

[0050] As used herein, the term “amino” means -NH2.

[0051] As used herein, the term “animal” includes, but is not limited to, humans and nonhuman vertebrates such as wild, domestic, and farm animals.321886535vlAttorney Docket No: 254409.000968 PATENT

[0052] As used herein, “area under the curve” or “AUC” refers to a pharmacokinetic parameter that quantifies the total exposure of an organism to a drug over time. The AUC is determined by plotting the concentration of the drug in the blood plasma against time and calculating the area under this curve. This parameter is typically expressed in units of concentration-time (e.g., ng*h / mL) and provides a comprehensive measure of the drug's bioavailability. The AUC is utilized to assess the extent and duration of drug exposure following administration and is critical in understanding the drug's absorption, distribution, metabolism, and excretion (ADME) characteristics. A higher AUC indicates greater drug exposure, while a lower AUC indicates less exposure.

[0053] As used herein, “bioavailability” refers to the extent at which an active pharmaceutical ingredient or active moiety is absorbed from a drug product and becomes available at the site of action. Bioavailability is quantitatively expressed as the area under the plasma concentrationtime curve (AUC).

[0054] 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.

[0055] As used herein, the term “compound” means all stereoisomers, tautomers, and isotopes of the compounds described herein.

[0056] 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.8321886535vlAttorney Docket No: 254409.000968 PATENT

[0057] As used herein, the term “contacting” means bringing together two elements in an in vitro system or an in vivo system.

[0058] As used herein, “Cmax” refers to the maximum concentration of a drug observed in the blood plasma after administration. Cmaxis a pharmacokinetic parameter that indicates the peak level of drug exposure and is typically expressed in units of concentration (e.g., ng / mL). This parameter provides critical information about the rate and extent of drug absorption. The value of Cmax may be used to assess the efficacy and potential toxicity of a drug, as higher peak concentrations may be associated with increased therapeutic effects or adverse reactions.

[0059] As used herein, “crystallized intelligence” refers to the ability to use knowledge, experience, and skills that one has acquired over time.

[0060] As used herein, the “degree” of a side effect refers to the severity or intensity of the side effect experienced by an individual as a result of a medication or treatment.

[0061] As used herein, “dosage” refers to the prescribed amount of a drug or therapeutic agent to be taken at one time or at specified intervals. In some embodiments, dosage encompasses both the quantity of the drag (e.g., milligrams, micrograms) and the frequency of administration (e.g., once daily, twice daily).

[0062] As used herein, “dose form” refers to the physical form in which a drag or therapeutic agent is produced and administered to a subject. The dose form determines how the drug is delivered to the body and can influence its absorption, distribution, metabolism, and excretion. Common dose forms include but are not limited to, tablets, capsules, liquids, injections, transdermal patches, inhalers, and topical creams or ointments. In the context of this application, the term “dose form” encompasses the various physical forms in which 5-{[5-(3-chlorophenyl)- 6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, can be formulated and administered to achieve the therapeutic outcomes described herein.

[0063] As used herein, “dose” refers to a specific quantity of a drug or therapeutic agent that is administered to a subject at one time or over a specified period. The dose is typically measured in units such as milligrams (mg), micrograms (pg), or milliliters (mL), depending on the form9321886535vlAttorney Docket No: 254409.000968 PATENT and concentration of the drug. In the context of this application, the term “dose” encompasses the amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, that is administered to achieve the intended therapeutic outcomes described herein. In some embodiments, the dose is the amount of the free form of 5- { [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine.

[0064] As used herein, “dosing regimen” refers to the schedule and frequency at which doses of a drug or therapeutic agent are administered to a subject over a specified period. A dosing regimen includes the amount of each dose (e.g., milligrams or micrograms), the timing of each dose (e.g., once daily, twice daily), and the duration of the treatment (e.g., days, weeks, months). In the context of this application, the term “dose regimen” encompasses the specific administration schedule for 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2- amine, or a pharmaceutically acceptable salt thereof.

[0065] As used herein, “dose schedule” refers to the specific timing and frequency at which doses of a drug or therapeutic agent are administered to a subject. The dose schedule includes details such as the time of day each dose is taken, the interval between doses (e.g., every 8 hours, once daily), and the total number of doses administered over a given period (e.g., daily, weekly). In the context of this application, the term “dose schedule”" encompasses the precise timing and frequency of administration for 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, to achieve the intended therapeutic outcomes described herein.

[0066] As used herein, “an effective dose” (ED) or “effective concentration” (EC) is the dose or concentration of a drug that produces a biological response. As used herein, “minimum effective dose” (MED) or “minimum effective concentration” (MEC) is the lowest dose or concentration of a drug that produces a biologic response.

[0067] As used herein, “full mutation” or “FM” in a gene refers to a significant alteration in the gene's DNA sequence that disrupts its normal function. A full mutation in the FMRI gene is characterized by a significant expansion of the CGG trinucleotide repeat in the gene's 5'10321886535vlAttorney Docket No: 254409.000968 PATENT untranslated region. Individuals with greater than 200 CGG repeats are considered to have a full FMRI mutation and are at risk for FXS or other associated conditions.

[0068] As used herein, “premutation” or “PM” in a gene refers to a genetic alteration that involves a smaller expansion of a repetitive sequence within a gene, which can cause fragile X pre-mutation-associated conditions. A premutation in the FMRI gene involves a smaller expansion of the CGG repeat region of between 55 and 200 repeats. While premutation carriers generally do not have FXS developmental disabilities, the premutation carries a risk of expanding to the full mutation in the next generation and can be associated with other Fragile X- associated conditions, such as Fragile X-Associated Tremor Ataxia Syndrome (FXTAS).

[0069] As used herein, “methylation” in a gene refers to the addition of methyl groups to the cytosine bases in the DNA sequence. A methylation in the FMRI gene refers to the addition of methyl groups to the cytosine bases in the FMRI gene, typically occurring in the promoter region and the expanded CGG repeat region.

[0070] As used herein, “fragile X syndrome” or “FXS” refers to a genetic disorder caused by a mutation in the FMRI gene located on the X chromosome. This mutation typically involves an expansion of the CGG trinucleotide repeat, leading to the silencing of the FMRI gene and a subsequent deficiency or absence of the FMRP. FXS is characterized by a range of cognitive, behavioral, and physical symptoms, including intellectual disability, developmental delays, social anxiety, hyperactivity, and distinctive facial features. The severity of symptoms can vary widely among affected individuals, with males generally exhibiting more pronounced manifestations due to the presence of only one X chromosome. FXS is the most common inherited cause of intellectual disability and autism spectrum disorders, and it presents significant challenges in terms of diagnosis, management, and treatment.

[0071] As used herein, the term “hydroxy” or “hydroxyl” means an -OH group.

[0072] As used herein, the term “hydroxyalkyl” or “hydroxylalkyl” means an alkyl group substituted by a hydroxyl group. Examples of a hydroxyalkyl include, but are not limited to, -CH2OH and -CH2CH2OH.11321886535vlAttorney Docket No: 254409.000968 PATENT

[0073] As used herein, “incidence” refers to the frequency or rate at which occurrences of a condition in a population or a subject during a defined time period. “Incidence” of a side effect refers to the frequency or rate at which occurrences of a side effect in a population or a subject during a defined time period. Decreased incidence of a side effect refers to 1) in a population, fewer individuals (including no individuals) within the population are experiencing the side effect, 2) in an individual who experiences the side effect, the frequency of the side effect is reduced (including the situation that the side effect does not occur), or both 1) and 2).

[0074] 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 term “mammal” includes, but is not limited to, a rodent (i.e., a mouse, a rat, or a guinea pig), a primate, a cat, a dog, a cow, a horse, a pig, or a human. In some embodiments, the mammal is a human.

[0075] As used herein, the phrase “inhibiting activity,” such as enzymatic or receptor activity, means reducing by any measurable amount the activity of an enzyme or receptor, as well as any associated biological response or system.

[0076] 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.

[0077] As used herein, “oral dosage form” refers to a type of pharmaceutical formulation designed to be taken by mouth and absorbed through the gastrointestinal tract. Common types of oral dosage forms include tablets, which are solid forms containing the active ingredient and excipients, designed for immediate, extended, or delayed release; capsules, which are solid forms with the active ingredient enclosed in a gelatin or polymer shell, available in immediate or controlled release; liquids, which are solutions, suspensions, or syrups with the active ingredient dissolved or suspended in a liquid medium; powders and granules, which are dry forms that can be mixed with a liquid before administration; and orally disintegrating tablets (ODTs), which are12321886535vlAttorney Docket No: 254409.000968 PATENT tablets that rapidly dissolve in the mouth without water. In the context of this application, “oral dosage form” includes various formulations of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, intended for oral administration to achieve the therapeutic outcomes described herein.

[0078] As used herein, “solid form” refers to a type of pharmaceutical formulation in which the active ingredient and any excipients are in a solid state. Solid forms are designed for oral administration and are typically more stable and convenient than liquid forms. Common examples of solid forms include tablets, capsules, powders, and granules. These formulations can be designed for various release profiles, such as immediate release, extended-release, or delayed release, to control the rate and duration of drug absorption. In the context of this application, “solid form” includes the various solid formulations of 5-{[5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, intended for to achieve the therapeutic outcomes described herein.

[0079] 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.

[0080] As used herein, the phrase “pharmaceutically acceptable” means those compounds, materials, compositions, and / or dosage forms that 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.13321886535vlAttorney Docket No: 254409.000968 PATENT

[0081] As used herein, the phrase “pharmaceutically acceptable salt(s)” includes, but is not limited to, salts of acidic or basic groups. Compounds that are basic in nature are capable of forming a wide variety of salts with various inorganic and organic acids. Acids that may be used to prepare pharmaceutically acceptable acid addition salts of such basic compounds are those that form non-toxic acid addition salts, i.e., salts containing pharmacologically acceptable anions including, but not limited to, sulfuric, thiosulfuric, citric, maleic, acetic, oxalic, hydrochloride, hydrobromide, hydroiodide, nitrate, sulfate, bisulfate, bisulfite, phosphate, acid phosphate, isonicotinate, borate, acetate, lactate, salicylate, citrate, acid citrate, tartrate, oleate, tannate, pantothenate, bitartrate, ascorbate, succinate, maleate, gentisinate. fumarate, gluconate, glucaronate, saccharate, formate, benzoate, glutamate, methanesulfonate, ethanesulfonate, benzenesulfonate, p-toluenesulfonate, bicarbonate, malonate, mesylate, esylate, napsydisylate, tosylate, besylate, orthophoshate. trifluoroacetate, and pamoate (i.e., l,T-methylene-bis-(2- hydroxy-3-naphthoate)) salts. Compounds that include an amino moiety may form pharmaceutically acceptable salts with various amino acids in addition to the acids mentioned above. Compounds that are acidic in nature are capable of forming base salts with various pharmacologically acceptable cations. Examples of such salts include, but are not limited to, alkali metal or alkaline earth metal salts and, particularly, calcium, magnesium, ammonium, sodium, lithium, zinc, potassium, and iron salts. The present embodiments include pharmaceutically acceptable salt of the compounds described herein. The present embodiments also include quaternary ammonium salts of the compounds described herein, where the compounds have one or more tertiary amine moieties.

[0082] As used herein, the term “phenyl” means -CGH . A phenyl group can be unsubstituted or substituted with one, two, or three suitable substituents.

[0083] 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.14321886535vlAttorney Docket No: 254409.000968 PATENT

[0084] As used herein, the terms “suitable substituent,” “substituent,” “optional substituent,” or the substituent for any optionally substituted group, means a group that does not nullify the synthetic or pharmaceutical utility of the compounds described herein or the intermediates useful for preparing them. Examples of “suitable substituent,” “substituent,” “optional substituent,” or the substituent for any optionally substituted group include but are not limited to: Ci-Cealkyl, Ci- Cealkenyl, Ci-Cealkynyl, Ci-Cealkoxy, phenyl, Cb-Cdieleroaiyl, C3-Ciocycloalkyl, Cs-Cearyloxy, -CN, -OH, oxo, halo, haloalkyl, -NO2, -CO2H, -NH2, -NH(Ci-Csalkyl), -N(Ci-C8alkyl)2, - NH(phenyl), -N(phenyl)2, -CHO, -CO(Ci-Cealkyl), -CO(phenyl), -CO2(Ci-C6alkyl), and - CO2(phenyl). One of skill in the art can readily choose a suitable substituent based on the stability and pharmacological and synthetic activity of the compounds described herein.

[0085] 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 the progression of the disorder or improved treatment, healing, elimination, or amelioration 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.

[0086] As used herein, Tmax refers to the time at which the maximum concentration (Cmax) of a drug is observed in the blood plasma after administration.

[0087] As used herein, “half-life” or “T1 / 2” refers to the time required for the concentration of a drug in the blood plasma to decrease by half after reaching its maximum concentration. The half-life is a pharmacokinetic parameter that provides insight into the duration of action of a drug and its rate of elimination from the body. It is typically expressed in units of time (e.g., hours or minutes).15321886535vlAttorney Docket No: 254409.000968 PATENT

[0088] As used herein, the term “treat.” “treated,” or “treating” means both therapeutic treatments wherein the object is to slow down (lessen) an undesired physiological condition, disorder, or disease, and therapeutic treatments wherein the object is to 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 compared to expected survival if no treatment is received. Treatment further includes prevention.

[0089] As used herein, 'with food' refers to the administration of an agent within a time frame starting approximately 30 minutes before food ingestion and extending to about 30 minutes after food ingestion. “Without food” or “fasted” refers to the administration of an agent outside this time frame.

[0090] 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 sub-combination of the members of such groups and ranges. For example, the term “Ci-galkyl” is specifically intended to individually disclose methyl, ethyl, propyl, C4alkyl, Csalkyl, and Cealkyl.

[0091] 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 that are, for brevity, described in the context of a single embodiment can also be provided separately or in any suitable subcombination.16321886535vlAttorney Docket No: 254409.000968 PATENT

[0092] It is understood that the present embodiments encompass 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 a non-limiting example, the mixture may be a racemate or may comprise unequal proportions of one particular stereoisomer over the other. Additionally, the compounds can be provided as substantially pure stereoisomers, diastereomers, and optical stereoisomers (such as epimers).

[0093] 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 contemplated in the present embodiments. Cis and / ram-geometric isomers of the compounds are also included within the scope of the 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.

[0094] Resolution of racemic mixtures of compounds can be carried out by any of the numerous methods known in the art, including, for example, chiral HPLC and fractional recrystallization using a chiral resolving acid, 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 active17321886535vlAttorney Docket No: 254409.000968 PATENT camphorsulfonic acids such as P-camphorsulfonic acid. Other resolving agents suitable for fractional crystallization methods include but are not limited to, stereoisomerically pure forms of a-methylbenzylamine (e.g., .S' and / ? 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.

[0095] Resolution 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 that have 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-l,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.

[0096] Compounds also include hydrates and solvates, as well as anhydrous and nonsolvated forms.

[0097] 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.

[0098] In some embodiments, the compounds, or salts thereof, are partially or substantially isolated. Partial separation can include, for example, a composition enriched in the compound of the embodiments. 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 about18321886535vlAttorney Docket No: 254409.000968 PATENT95%, at least about 97%, or at least about 99% by weight of the compound of the embodiments, or salt thereof. Methods for isolating compounds and their salts are routine in the art.

[0099] 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 lengths, 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 the dicarbonyl unit to adopt an anti-arrangement of the two carbonyl moiety and alter the periodicity of the compound.Pyromellitic anhydride still represents 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 monodisperse compounds with molecular weights approaching 5,000 Daltons. Other substitution patterns are equally effective.

[0100] The compounds also include derivatives referred to as prodrugs.

[0101] 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.Methods of Treating FXS and Related Symptoms or Indications

[0102] Provided herein is a method of treating FXS, comprising administering to a subject in need thereof a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-19321886535vlAttorney Docket No: 254409.000968 PATENT yl]methyl}pyrimidin-2-aminepharmaceutically acceptable salt thereof.

[0103] The present disclosure provides a method of treating, reducing, improving, or ameliorating FXS-related indications, conditions, or symptoms, including (but not limited to) intellectual disability, autism spectrum disorder behaviors, Attention Deficit Hyperactivity Disorder (ADHD) symptoms, high levels of anxiety, seizures, sensory processing issues, speech and language delays, behavioral problems, distinctive physical features (such as a long face, large ears, and hyperflexible joints), connective tissue problems, and FXTAS.

[0104] In some embodiments, the subject in need thereof has one or more of developmental delays, IDD, intellectual deficits, learning disabilities, anxiety, depression, obsessive-compulsive behaviors, ADD, hyperactivity disorder, aberrant behavior, social and communication deficits, autism spectrum disorder, seizures, insomnia, obesity, and hypotonia.

[0105] Further provided herein is a method of treating, reducing, or ameliorating one or more of developmental delays, IDD, intellectual deficits, learning disabilities, anxiety, depression, obsessive-compulsive behaviors, ADD, hyperactivity disorder, aberrant behavior, social and communication deficits, autism spectrum disorder, seizures, insomnia, obesity, and hypotonia in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0106] Also provided herein is a method of treating, reducing, or ameliorating developmental delays in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.20321886535vlAttorney Docket No: 254409.000968 PATENT

[0107] Additionally provided herein is a method of treating, reducing, or ameliorating IDD, intellectual deficits, or learning disabilities in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0108] Additionally provided herein is a method of treating, reducing, or ameliorating anxiety, depression, or obsessive-compulsive behaviors in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0109] Additionally provided herein is a method of treating, reducing, or ameliorating ADD, hyperactivity disorder, autism spectrum disorder, aberrant behavior, or social and communication deficits in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0110] Additionally provided herein is a method of treating, reducing, or ameliorating seizures, insomnia, obesity, or hypotonia in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0111] Additionally provided herein is a method of treating FXTAS comprising administering to a subject in need thereof a therapeutically effective amount of 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0112] Additionally provided herein is a method of improving cognitive abilities in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{ [5- (3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0113] In some embodiments, the method improves cognitive abilities in a subject having FXS comprising administering to the subject a therapeutically effective amount of 5-{[5-(3-21321886535vlAttorney Docket No: 254409.000968 PATENT chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and the subject does not experience emesis or nausea.

[0114] In some embodiments, less than about 50%, less than about 40%, less than about 30%, less than about 20%, less than about 10%, less than about 5%, or less than about 1% of the subjects being administered the therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof experience side effects.

[0115] The side effects experienced by the subjects may comprise one or more of emesis, headache, nausea, dizziness, vertigo, fatigue, diarrhea, weight loss, back pain, abdominal pain, decreased appetite, nasopharyngitis, upper respiratory tract infections, palpitations, changes in heart rate, and insomnia.

[0116] In some embodiments, the side effect is nausea and emesis.

[0117] In some embodiments, the side effect is nausea or emesis.

[0118] In some embodiments, the side effect is nausea.

[0119] In a further embodiments, the side effect is emesis.

[0120] In some embodiments, the subject experiences side effects following less than about 50%, less than about 40%, less than about 30%. less than about 20%, less than about 10%, less than about 5%, or less than about 1% of administration occurrences.

[0121] In some embodiments, the method improves cognitive abilities in a subject having FXS by administering a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and the subject does not experience emesis.

[0122] In some embodiments, the method improves cognitive abilities in subjects having FXS by administering a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and less than about 50%, less than about 40%, less than about 30%, less than about 20%, or less than about 10%, less than about 5%, or less than about 1% of the subjects experience emesis.22321886535vlAttorney Docket No: 254409.000968 PATENT

[0123] In some embodiments, the method improves cognitive abilities in subjects having FXS by administering a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and less than about 10% of the subjects experience emesis.

[0124] In some embodiments, the method improves cognitive abilities in a subject having FXS by administering a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and the subject experiences emesis following less than about 50%, less than about 40%, less than about 30%. less than about 20%, or less than about 10%, less than about 5%, or less than about 1% of administration occurrences.

[0125] In some embodiments, the method improves cognitive abilities in a subject having FXS by administering a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and the subject experiences emesis following less than about 10% of administration occurrences.

[0126] In some embodiments, the method improves measures of one primary endpoint and one or more of the secondary endpoints described below:

[0127] A primary point to measure cognitive ability is often referred to as a “primary endpoint” or “primary outcome measure.” This is a specific, predefined criterion used to evaluate the effectiveness of an intervention or treatment in improving cognitive function. In some embodiments, primary endpoints for measuring cognitive ability include (but are not limited to): i) Global Cognitive Composite Scores: These are aggregate scores derived from a battery of cognitive tests that assess multiple domains of cognitive function. Examples include the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) and the National Institute of Health Toolbox Cognition Battery (NIHTB-CB) composite scores; ii) Specific Cognitive Tests: Individual cognitive tests that target specific domains such as memory, attention, executive function, and processing speed. Examples include the23321886535vlAttorney Docket No: 254409.000968 PATENTMini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA). and specific subtests from the Wechsler Adult Intelligence Scale (WAIS) or the Stanford-Binet Intelligence Scales; iii) Functional Cognitive Assessments: Measures that assess the impact of cognitive function on daily living activities and overall quality of life. Examples include the Functional Activities Questionnaire (FAQ), the Cognitive Function Instrument (CFI), and iv) Neuropsychological Test Batteries: Comprehensive sets of tests that evaluate a wide range of cognitive abilities. Examples include the Cambridge Neuropsychological Test Automated Battery (CANTAB) and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS).

[0128] In certain embodiments, the RBANS assessment is conducted using the Immediate Memory Domain, which includes the list memory and story immediate memory subtests, as well as the Delayed Memory Domain, comprising the list recall, list recognition, and story delayed recall subtests.

[0129] In some embodiments, the method improves cognitive abilities as measured by the NIHTB-CB composite scores.

[0130] In some embodiments, the method improves one or more cognitive abilities or measures in reading comprehension, vocabulary comprehension, executive function, cognitive flexibility, inhibitory control, sustained attention, episodic memory, visual memory, picture sequence memory, pattern comparison, processing speed, working memory, and crystallized intelligence.

[0131] In some embodiments, the method improves levels, scales, or scores in one or more of the following measures from the NIHTB-CB: i) Picture Sequence Memory Test: Assesses episodic memory, which is the ability to recall sequences of events or pictures in the correct order;24321886535vlAttorney Docket No: 254409.000968 PATENT ii) Flanker Inhibitory Control and Attention Test: Measures executive function, specifically inhibitory control (the ability to suppress responses to irrelevant stimuli) and attention (the ability to maintain focus on relevant stimuli); iii) List Sorting Working Memory Test: Evaluates working memory, which is the ability to temporarily hold and manipulate information for cognitive tasks such as reasoning, learning, and comprehension; iv) Dimensional Change Card Sort Test: Assesses cognitive flexibility, a component of executive function, which is the ability to switch between different tasks or mental sets and adapt to changing rules or demands; v) Pattern Comparison Processing Speed Test: Measures processing speed, which is the ability to quickly and accurately process simple information; vi) Oral Reading Recognition Test: Assesses reading ability, specifically the ability to recognize and pronounce words accurately; vii) Picture Vocabulary Test: Measures receptive vocabulary, which is the ability to understand and recognize the meaning of spoken words; viii) Auditory Verbal Learning Test (AVLT): Assesses verbal learning and memory, which is the ability to encode, store, and retrieve verbal information presented orally: ix) Crystallized Cognition Composite (CCC): Measures crystallized intelligence, which refers to the ability to use skills, knowledge, and experience. It is often associated with verbal abilities and knowledge acquired over time.

[0132] In some embodiments, the improvement in cognitive abilities comprises improvement in one or more of reading comprehension, vocabulary comprehension, executive function, cognitive flexibility, inhibitory control, sustained attention, episodic memory, visual memory, picture sequence memory, pattern comparison, processing speed, working memory, and crystallized intelligence.

[0133] In some embodiments, the method improves cognitive abilities, including memory (both episodic and working memory), executive function (inhibitory control, attention, and25321886535vlAttorney Docket No: 254409.000968 PATENT cognitive flexibility), processing speed, and language abilities (reading and vocabulary comprehension). In some embodiments, the method improves academic performance, optionally comprising mathematical skills or language skills.

[0134] Secondary endpoints for cognitive endpoints are additional measures used to evaluate the effects of the intervention. These endpoints provide supplementary information that complements the primary endpoint. Secondary endpoints can include various cognitive domains and related functional outcomes, including (not limited to): i) Specific Cognitive Tests: Individual tests that target specific cognitive domains, such as memory, attention, executive function, and processing speed. Examples include the Wechsler Memory Scale (WMS), Trail Making Test (TMT), and Stroop Test; ii) Quality of Life Measures: Assessments that evaluate the impact of cognitive function on overall quality of life, including emotional well-being, social functioning, and daily activities. Examples include the Quality of Life in Alzheimer's Disease (QoL-AD) scale and the Short Form Health Survey (SF-36); iii) Functional Assessments: Measures that assess the ability to perform daily living activities and maintain independence. Examples include the Functional Activities Questionnaire (FAQ) and the Instrumental Activities of Daily Living (IADL) scale; iv) Behavioral and Psychological Symptoms: Assessments that evaluate the presence and severity of behavioral and psychological symptoms associated with cognitive impairment, such as depression, anxiety, and agitation. Examples include the Neuropsychiatric Inventory (NPI) and the Geriatric Depression Scale (GDS); v) Neuroimaging and Biomarkers: Objective measures that provide insights into the biological underpinnings of cognitive changes, such as brain imaging (MRI, PET scans) and biomarkers (cerebrospinal fluid analysis, blood tests, or electroencephalography (EEG)); vi) Caregiver Assessments: Evaluations of the caregiver's perspective on the patient's cognitive function and overall well-being. Examples include the Caregiver Global Impression of Improvement (CaGI-I) and the Zarit Burden Interview (ZB I); and26321886535vlAttorney Docket No: 254409.000968 PATENT vii) Educational and Occupational Outcomes: Measures that assess the impact of cognitive function on academic performance and work-related abilities. Examples include standardized academic tests and work productivity assessments.

[0135] In some embodiments, the method improves academic performance, optionally comprising mathematical skills or language skills.

[0136] In some embodiments, the method improves one or more of measures selected from: i) Numerical rating scale (NRS) scores based on subject-specific behaviors within the domains of daily function and language; ii) Caregiver Global Impression of Improvement (CaGI-I) levels for the general domains of daily function and language; iii) Clinical Global Impression Improvement (CGI-I) levels for investigator-rated general domains of daily function and language; iv) Vineland-3 Adaptive Behavior Scale (Vineland-3) based on composite scores and domain scores from communication, daily living skills, and socialization: v) Verbal Knowledge test scores from the Stanford-Binet Intelligence Scales, Fifth Edition (SB-5); and vi) Levels of Picture Sequence Memory, Flanker Inhibitory Control and Attention, List Sorting Working Memory, Dimensional Change Card Sort, and / or Speeded Matching in the NIHTB-CB test.

[0137] In some embodiments, the method improves levels, scales, or scores of Crystallized Cognition Composite (CCC).

[0138] In some embodiments, the method improves levels, scales, or scores in the Speeded Matching test of the NIHTB-CB.

[0139] In some embodiments, the method reduces Aberrant Behavior Checklist (ABC) scores and / or Mood Scale (ADAMS) scores.

[0140] In some embodiments, the method reduces or ameliorates one or more of aberrant behavior, anxiety, depression, and the degree of electroencephalography (EEG) abnormalities.27321886535vlAttorney Docket No: 254409.000968 PATENT

[0141] In some embodiments, the subject is a pediatric patient.

[0142] In some embodiments, the subject is under 17 years old.

[0143] In some embodiments, the subject is aged 6-17 years.

[0144] In some embodiments, the subject is aged 12 to less than 17 years.

[0145] In some embodiments, the subject is aged 3 years and up.

[0146] In some embodiments, the subject is aged 9 years and up.

[0147] In some embodiments, the subject is aged 2 to 11 years.

[0148] In some embodiments, the subject is aged 0 days to 23 months.

[0149] In some embodiments, the subject is an adult.

[0150] In some embodiments, the subject is aged 18-45 years.

[0151] In some embodiments, the subject is aged 65 years or older.

[0152] In some embodiments, the subject is male.

[0153] In some embodiments, the subject has a full mutation (FM), a premutation (PM), or a methylation in the FMRI gene.Doses and Dosing Schedule of 5-{[5-(3-Chlorophenyl)-6-Methoxypyridin-3- yl]Methyl}Pyrimidin-2-Amine, or a Pharmaceutically Acceptable Salt Thereof

[0154] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.05 mg to about 50 mg per day. The amount of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof is based on the free base form of 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin- 2-amine.

[0155] In some embodiments, the method comprises administering 5-{ [5-(3-chlorophenyl)- 6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, in a dose of about 0.05 mg to about 0.5 mg, about 0.05 mg to about 5 mg, about 0.05 mg to about 10 mg, about 0.05 mg to about 20 mg, about 0.05 mg to about 30 mg, about 0.05 mg to about 40 mg, about 0.05 mg to about 50 mg, about 0.1 mg to about 5 mg, about 0.1 mg to about 10 mg,28321886535vlAttorney Docket No: 254409.000968 PATENT about 0.1 mg to about 20 mg, about 0.1 mg to about 30 mg, about 0.1 mg to about 40 mg, about 0.1 mg to about 50 mg, about 0.5 mg to about 1 mg, about 0.5 mg to about 5 mg, about 0.5 mg to about 10 mg, about 0.5 mg to about 20 mg, about 0.5 mg to about 30 mg, about 0.5 mg to about 40 mg, about 0.5 mg to about 50 mg, about 1 mg to about 5 mg, about 1 mg to about 10 mg, about 1 mg to about 20 mg, about 1 mg to about 30 mg, about 1 mg to about 40 mg, about 1 mg to about 50 mg, about 5 mg to about 10 mg, about 5 mg to about 20 mg, about 5 mg to about 30 mg, about 5 mg to about 40 mg, about 5 mg to about 50 mg, about 10 mg to about 20 mg, about 20 mg to about 30 mg, about 30 mg to about 40 mg, or about 40 mg to about 50 mg.

[0156] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.05 mg to about 20 mg per day.

[0157] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.1 mg to about 20 mg per day.

[0158] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.5 mg to about 15 mg per day.

[0159] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.5 mg to about 5 mg per day.

[0160] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 1 mg to about 5 mg per day.

[0161] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.5 mg per day.29321886535vlAttorney Docket No: 254409.000968 PATENT

[0162] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 1 mg per day.

[0163] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 2 mg per day.

[0164] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 2.5 mg per day.

[0165] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 3 mg per day.

[0166] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 4 mg per day.

[0167] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 5 mg per day.

[0168] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, is administered in a dose of about 7.5 mg per day.

[0169] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- ylJmethyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.002 mg / kg to about 0.5 mg / kg per day, about 0.002 mg / kg to about 0.2 mg / kg per day, about 0.002 mg / kg to about 0.1 mg / kg, about 0.002 mg / kg to about 0.05 mg / kg, about 0.002 mg / kg to about 0.02 mg / kg, about 0.02 mg / kg to about 0.5 mg / kg per day, about 0.02 mg / kg to about 0.2 mg / kg per day, about 0.02 mg / kg to about 0.1 mg / kg per day, and about 0.02 mg / kg to30321886535vlAttorney Docket No: 254409.000968 PATENT about 0.05 mg / kg per day, about 0.05 mg / kg per day: about 0.05 mg / kg to about 0.5 mg / kg per day, about 0.05 mg / kg to about 0.2 mg / kg per day, about 0.05 mg / kg to about 0.1 mg / kg per day, about 0.1 mg / kg to about 0.5 mg / kg per day, or about 0.1 mg / kg to about 0.2 mg / kg per day.

[0170] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.002 mg / kg to about 0.2 mg / kg per day.

[0171] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a single dose or multiple doses per day.

[0172] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered once per day.

[0173] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered twice per day.

[0174] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in multiple doses per day.

[0175] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, is administered in 1 - 5 doses per day.Food Effects

[0176] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered from approximately 30 minutes before, to approximately 30 minutes after, food ingestion.

[0177] In some embodiments, administering with food reduces, ameliorates, or minimizes one or more side effects compared to administering 5-{ [5-(3-chlorophenyl)-6-31321886535vlAttorney Docket No: 254409.000968 PATENT methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, more than 30 minutes before or after food ingestion.

[0178] In some embodiments, the side effects include one or more of emesis, headache, nausea, dizziness, vertigo, fatigue, diarrhea, weight loss, back pain, abdominal pain, decreased appetite, nasopharyngitis, upper respiratory tract infections, palpitations, changes in heart rate, and insomnia.

[0179] In some embodiments, the side effect is nausea and emesis.

[0180] In some embodiments, the side effect is nausea or emesis.

[0181] In some embodiments, the side effect is nausea.

[0182] In some embodiments, the side effect is emesis.

[0183] In some embodiments, administering with food delays the release of 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, as measured by Tmax, compared to administering more than 30 minutes before or after food ingestion.

[0184] In some embodiments, administering with food increases Tmaxby approximately 0.5 hour to 10 hours compared to administering more than 30 minutes before or after food ingestion.

[0185] In some embodiments, administering with food increases Tmaxby approximately 1 hour to 8 hours.

[0186] In some embodiments, administering with food increases Tmax by approximately 1 hour to 7 hours, 2 hours to 8 hours, 3 hours to 8 hours, 4 hours to 8 hours, or 6 hours to 8 hours.

[0187] In some embodiments, administering with food increases Tmaxby approximately 1 hour. In a further embodiment, administering with food increases Tmaxby approximately 1 hour with a dose at 7.5 mg.

[0188] In some embodiments, administering with food increases Tmaxby approximately 7 hours. In a further embodiment, administering with food increases Tmaxby approximately 7 hours with a dose at 3 mg.32321886535vlAttorney Docket No: 254409.000968 PATENT

[0189] In some embodiments, administering with food decreases Cmax Of 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, compared to administering more than 30 minutes before or after food ingestion.

[0190] In some embodiments, the Cmax when administered with food is approximately 10% to 90% of the Cmax when administered more than 30 minutes before or after food ingestion. In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2- amine, or a pharmaceutically acceptable salt thereof, is administered in a dose described above or below. In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose about 0.5 mg to about 5 mg.

[0191] In some embodiments, the Cmax when administered with food is approximately 30% to 80% of the Cmax when administered more than 30 minutes before or after food ingestion.

[0192] In some embodiments, the Cmax when administered with food is approximately 60% to 70% of the Cmax when administered more than 30 minutes before or after food ingestion.

[0193] In some embodiments, the Cmax when administered with food at a dose of 3 mg is approximately 30% of the Cmax when administered more than 30 minutes before or after food ingestion at a dose of 3 mg.

[0194] In some embodiments, the Cmax when administered with food at a dose of 7.5 mg is approximately 80% of the Cmax when administered more than 30 minutes before or after food ingestion at a dose of 7.5 mg.

[0195] In some embodiments, administering with food increases the bioavailability of 5- { [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, as measured by AUC, compared to administering without food.

[0196] In some embodiments, the AUC when administered with food is approximately 100% to 150% of the AUC when administered more than 30 minutes before or more than 30 minutes after food ingestion.33321886535vlAttorney Docket No: 254409.000968 PATENT

[0197] In some embodiments, the AUC when administered with food is approximately 105% to 150% of the AUC when administered more than 30 minutes before or more than 30 minutes after food ingestion.

[0198] In some embodiments, the AUC when administered with food is approximately 105% to 120% of the AUC when administered more than 30 minutes before or more than 30 minutes after food ingestion.

[0199] In some embodiments, the AUC when administered with food at a 3 mg dose is approximately 105% of the AUC at a 3 mg dose when administered more than 30 minutes before or more than 30 minutes after food ingestion

[0200] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered with food.

[0201] In some embodiments, 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered within about 30 minutes before or after food consumption.

[0202] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered without food.Brain Penetration Capabilities of 5-{[5-(3-Chlorophenyl)-6-Methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a Pharmaceutically Acceptable Salt Thereof

[0203] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, penetrates the blood-brain barrier.

[0204] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain-to- plasma concentration ratio of about 2:1 to about 7:1.34321886535vlAttorney Docket No: 254409.000968 PATENT

[0205] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain-to- plasma concentration ratio of about 4:1 to about 6:1.

[0206] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain-to- plasma concentration ratio of about 4:1 to about 5:1.

[0207] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a plasma concentration at about 0.2 ng / mL to 50 ng / mL.

[0208] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a plasma concentration at 0.2 ng / mL to about 1 ng / mL, about 0.2 ng / mL to about 5 ng / mL, about 0.2 ng / mL to about 10 ng / mL, about 0.2 ng / mL to about 20 ng / mL, about 0.2 ng / mL to about 30 ng / mL, about 0.2 ng / mL to about 40 ng / mL, about 0.2 ng / mL to about 50 ng / mL, 0.5 ng / mL to about 1 ng / mL, about 0.5 ng / mL to about 5 ng / mL, about 0.5 ng / mL to about 10 ng / mL, about 0.5 ng / mL to about 20 ng / mL, about 0.5 ng / mL to about 30 ng / mL, about 0.5 ng / mL to about 40 ng / mL, about 0.5 ng / mL to about 50 ng / mL, 1 ng / mL to about 5 ng / mL, about 1 ng / mL to about 10 ng / mL, about 1 ng / mL to about 20 ng / mL, about 1 ng / mL to about 30 ng / mL, about 1 ng / mL to about 40 ng / mL, about 1 ng / mL to about 50 ng / mL, 5 ng / mL to about 10 ng / mL, about 5 ng / mL to about 20 ng / mL, about 5 ng / mL to about 30 ng / mL, about 5 ng / mL to about 40 ng / mL, about 5 ng / mL to about 50 ng / mL, 10 ng / mL to about 20 ng / mL, about 10 ng / mL to about 30 ng / mL, about 10 ng / mL to about 40 ng / mL, about 10 ng / mL to about 50 ng / mL, 20 ng / mL to about 30 ng / mL, about 20 ng / mL to about 40 ng / mL, about 20 ng / mL to about 50 ng / mL, about 30 ng / mL to about 40 ng / mL, or about 30 ng / mL to about 50 ng / mL.

[0209] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a plasma35321886535vlAttorney Docket No: 254409.000968 PATENT concentration at about 0.5 ng / mL to 30 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.

[0210] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- ylJmethyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a plasma concentration at about 1 ng / mL to about 30 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.

[0211] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a plasma concentration at about 1 ng / mL to about 10 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.

[0212] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, has a plasma concentration at about 3 ng / mL to about 10 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.

[0213] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain concentration of about 4 ng / mL to about 180 ng / mL while its plasma concentration is at about 1 ng / mL to about 30 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.

[0214] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain concentration of about 12 ng / mL to about 60 ng / mL while its plasma concentration is at about 3 ng / mL to about 10 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.

[0215] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain36321886535vlAttorney Docket No: 254409.000968 PATENT concentration of about 4 ng / mL to about 180 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.

[0216] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- ylJmethyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain concentration of about Ing / mL to about 10 ng / mL, about 3ng / mL to about 7 ng / mL, about 4 ng / mL to about 6 ng / mL about one hour after administration with a dose of about 1 mg.

[0217] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain concentration of about 5 ng / mL about one hour after administration with a dose of about 1 mg.

[0218] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain concentration of about 10 ng / mL to about 30 ng / mL, about 12 ng / mL to about 28 ng / mL, or about 15 ng / mL to about 20 ng / mL about one hour after administration with a dose of about 2.5 mg.

[0219] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain concentration of about 17 ng / mL about one hour after administration with a dose of about 2.5 mg.

[0220] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, has a brain concentration of about 25 ng / mL to about 55 ng / mL, about 30 ng / mL to about 50 ng / mL, about 35 ng / mL to about 45 ng / mL in the brain about one hour after administration with a dose of about 5 mg.

[0221] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain concentration of about 41 ng / mL in the brain about one hour after administration with a dose of about 5 mg.37321886535vlAttorney Docket No: 254409.000968 PATENTMRM-3379’s Effect of Reducing, Ameliorating, or Minimizing Side Effects

[0222] Common side effects of PDE4 inhibitors include headaches, dizziness, and insomnia affecting the central nervous system (CNS); vertigo and balance disturbances related to the vestibular system; gastrointestinal (GI) issues such as nausea, diarrhea, and abdominal pain; and cardiovascular side effects including palpitations and potential changes in heart rate. Additionally, the vomiting center in the brainstem, particularly the nucleus of tractus solitarius, and the chemoreceptor trigger zone (area postrema) can be affected, leading to nausea and vomiting (emesis). These side effects can limit the use and patient compliance of PDE4 inhibitors, despite their therapeutic benefits.

[0223] The present disclosure presents that MRM-3379 is effective at much lower plasma concentrations than other PDE4 inhibitors (e.g., Examples 1 and 5). The plasma MEC is lower than the plasma MEC of other PDE4 inhibitors. As a result, MRM-3379 is associated with fewer side effects and a lower degree of severity for one or more side effects.

[0224] In some embodiments, the degree of one or more side effects resulting from administering 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is decreased relative to the one or more side effects resulting from administering another PDE4 inhibitor.

[0225] In some embodiments, the incidence of one or more side effects resulting from administering 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is decreased relative to the one or more side effects resulting from administering another PDE4 inhibitor.

[0226] In some embodiments, the degree and the incidence of one or more side effects resulting from administering 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin- 2-amine, or a pharmaceutically acceptable salt thereof, are both decreased relative to the one or more side effects resulting from administering another PDE4 inhibitor.

[0227] In some embodiments, the degree of one or more side effects resulting from administering 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a38321886535vlAttorney Docket No: 254409.000968 PATENT pharmaceutically acceptable salt thereof, is decreased relative to the one or more side effects resulting from administering another PDE4 inhibitor at the same dose.

[0228] In some embodiments, the incidence of one or more side effects resulting from administering 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-ylJmethyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is decreased relative to the one or more side effects resulting from administering another PDE4 inhibitor at the same dose.

[0229] In some embodiments, both the degree and the incidence of one or more side effects resulting from administering 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, are decreased relative to the one or more side effects resulting from administering another PDE4 inhibitor at the same dose.

[0230] In some embodiments, the degree of one or more side effects resulting from administering 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is decreased relative to one or more side effects resulting from administering another PDE4 inhibitor, wherein the administration of 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and the administration of another PDE4 inhibitor are at their corresponding minimum effective doses.

[0231] In some embodiments, the incidence of one or more side effects resulting from administering 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is decreased relative to one or more side effects resulting from administering another PDE4 inhibitor, wherein the administration of 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and the administration of another PDE4 inhibitor are at their corresponding minimum effective doses.

[0232] In some embodiments, both the degree and the incidence of one or more side effects resulting from administering 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-39321886535vlAttorney Docket No: 254409.000968 PATENT yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, are decreased relative to one or more side effects resulting from administering another PDE4 inhibitor, wherein the administration of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- ylJmethyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and the administration of another PDE4 inhibitor are at their corresponding minimum effective doses.

[0233] In some embodiments, the degree of one or more side effects resulting from administering 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is decreased relative to one or more side effects resulting from administering another PDE4 inhibitor, when the administration of another PDE4 inhibitor achieves the same brain concentration as the administration of 5-{ [5-(3-chlorophenyl)- 6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof. In some embodiments, the incidence of one or more side effects resulting from administering 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is decreased relative to one or more side effects resulting from administering another PDE4 inhibitor, when the administration of another PDE4 inhibitor achieves the same brain concentration as the administration of 5-{ [5-(3-chlorophenyl)- 6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0234] In some embodiments, both the degree and the incidence of one or more side effects resulting from administering 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, are decreased relative to one or more side effects resulting from administering another PDE4 inhibitor, when the administration of another PDE4 inhibitor achieves the same brain concentration as the administration of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof. In some embodiments, the brain concentration is an effective concentration (EC) in the brain.40321886535vlAttorney Docket No: 254409.000968 PATENT

[0235] In some embodiments, the minimum effective concentration (MEC) in plasma for 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is lower than the MEC in plasma for another PDE4 inhibitor.

[0236] In some embodiments, the minimum effective dose (MED) for 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is lower than the MED for another PDE4 inhibitor.

[0237] In some embodiments, the another PDE4 inhibitor is roflumilast (Daliresp), apremilast (Otezla), crisaborole (Eucrisa), ibudilast (MN-166), or zatolmilast (BPN14770).

[0238] In some embodiments, the another PDE4 inhibitor is zatolmilast or roflumilast.

[0239] In some embodiments, the side effects comprise common side effects of PDE4 inhibitors.

[0240] In some embodiments, the side effects comprise one or more of emesis, headache, nausea, dizziness, vertigo, fatigue, diarrhea, weight loss, back pain, abdominal pain, decreased appetite, nasopharyngitis, upper respiratory tract infections, palpitations, changes in heart rate, and insomnia.

[0241] In some embodiments, the side effect is nausea and emesis.

[0242] In some embodiments, the side effect is nausea or emesis.

[0243] In some embodiments, the side effect is nausea.

[0244] In some embodiments, the side effect is emesis.Pharmacokinetic Profile of 5-{[5-(3-Chlorophenyl)-6-Methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a Pharmaceutically Acceptable Salt Thereof

[0245] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising an AUC at about 1 ng*h / mL to about 200 ng*h / mL.

[0246] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo41321886535vlAttorney Docket No: 254409.000968 PATENT plasma profile comprising an AUC at about 1 ng*h / mL to about 10 ng*h / mE, about 1 ng*h / mL to about 50 ng*h / mL, about 1 ng*h / mL to about 100 ng*h / mL, about 1 ng*h / mL to about 150 ng*h / mE, about 1 ng*h / mE to about 200 ng*h / mE, about 10 ng*h / mL to about 50 ng*h / mE, about 10 ng*h / mE to about 100 ng*h / mL, about 10 ng*h / mL to about 150 ng*h / mE, about 10 ng*h / mL to about 200 ng*h / mL, about 50 ng*h / mL to about 100 ng*h / mL, about 50 ng*h / mL to about 150 ng*h / mL, about 50 ng*h / mL to about 200 ng*h / mL, about 100 ng*h / mL to about 150 ng*h / mL, or about 100 ng*h / mL to about 200 ng*h / mL

[0247] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising an AUC at about 3 ng*h / mL to about 100 ng*h / mL.

[0248] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising an AUC at about 6 ng*h / mL to about 60 ng*h / mE.

[0249] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising an AUC at about 10 ng*h / mE to about 30 ng*h / mE.

[0250] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising a Cmax of about 0.01 ng / mE to about 300 ng / mE.

[0251] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising a Cmax of about 0.05 ng / mE to about 50 ng / mL.

[0252] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising a Cma of about 0.2 ng / mE to about 20 ng / mE.

[0253] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo42321886535vlAttorney Docket No: 254409.000968 PATENT plasma profile comprising a Cmax of about 0.02 ng / mL to about 1 ng / mL, about 0.02 ng / mL to about 5 ng / mL, about 0.02 ng / mL to about 10 ng / mL, about 0.02 ng / mL to about 50 ng / mL, about 0.02 ng / mL to about 100 ng / mL, about 0.02 ng / mL to about 300 ng / mL, 0.05 ng / mL to about 1 ng / mL, about 0.05 ng / mL to about 5 ng / mL, about 0.05 ng / mL to about 10 ng / mL, about 0.05 ng / mL to about 50 ng / mL, about 0.05 ng / mL to about 100 ng / mL, about 0.05 ng / mL to about 300 ng / mL, about 1 ng / mL to about 5 ng / mL, about 1 ng / mL to about 10 ng / mL, about 1 ng / mL to about 50 ng / mL, about 1 ng / mL to about 100 ng / mL, about 1 ng / mL to about 300 ng / mL, about 5 ng / mL to about 10 ng / mL, about 5 ng / mL to about 50 ng / mL, about 5 ng / mL to about 100 ng / mL, about 5 ng / mL to about 300 ng / mL, about 10 ng / mL to about 50 ng / mL, about 10 ng / mL to about 100 ng / mL, about 10 ng / mL to about 200 ng / mL, about 10 ng / mL to about 300 ng / mL, about 20 ng / mL to about 50 ng / mL, about 20 ng / mL to about 100 ng / mL, about 20 ng / mL to about 200 ng / mL, about 20 ng / mL to about 300 ng / mL, about 50 ng / mL to about 100 ng / mL, about 50 ng / mL to about 150 ng / mL, about 50 ng / mL to about 200 ng / mL, about 50 ng / mL to about 300 ng / mL, about 100 ng / mL to about 150 ng / mL, about 100 ng / mL to about 200 ng / mL, about 100 ng / mL to about 250 ng / mL, or about 100 ng / mL to about 300 ng / mL.

[0254] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising a Cmax of about 1 ng / mL to about 10 ng / mL.

[0255] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising a time to reach maximum plasma concentration (Tmax) of about 0.1 hour to about 24 hours after administration.

[0256] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising a time to reach maximum plasma concentration (Tmax) of about 0.1 hour to about 24 hours, about 0.1 hour to about 15 hours, about 0.1 hour to about 12 hours,43321886535vlAttorney Docket No: 254409.000968 PATENT about 0.1 hour to about 10 hours, about 0.1 hour to about 6 hours, about 0.1 hour to about 3 hours, about 0.1 hour to about 1 hour, about 0.3 hour to about 24 hours, about 0.3 hour to about 15 hours, about 0.3 hour to about 12 hours, about 0.3 hour to about 10 hours, about 0.3 hour to about 6 hours, about 0.3 hour to about 3 hours, about 0.3 hour to about 1 hour, about 0.5 hour to about 24 hours, about 0.5 hour to about 15 hours, about 0.5 hour to about 12 hours, about 0.5 hour to about 10 hours, about 0.5 hour to about 6 hours, about 0.5 hour to about 3 hours, about 0.5 hour to about 1 hour, about 1 hour to about 24 hours, about 1 hour to about 15 hours, about1 hour to about 12 hours, about 1 hour to about 10 hours, about 1 hour to about 6 hours, about 1 hour to about 3 hours, about 2 hours to about 24 hours, about 2 hours to about 15 hours, about 2 hours to about 12 hours, about 2 hours to about 10 hours, about 2 hours to about 6 hours, about2 hours to about 3 hours, about 3 hours to about 24 hours, about 3 hours to about 15 hours, about 3 hours to about 12 hours, about 3 hours to about 10 hours, or about 3 hours to about 6 hours after administration.

[0257] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising a time to reach maximum plasma concentration (Tmax) of about 0.3 hour to about 15 hours.

[0258] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising a Tmaxof about 1 hour to about 10 hours after administration.

[0259] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a half-life (T1 / 2) duration of about 1 hour to about 50 hours.

[0260] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a half-life (T1 / 2) duration of about 1 hour to about 2 hours, about 1 hour to about 4 hours, about 1 hour to about 6 hours, about 1 hour to about 10 hours, about 1 hour to about 20 hours, about 1 hour to44321886535vlAttorney Docket No: 254409.000968 PATENT about 30 hours, about 1 hour to about 40 hours, about 1 hour to about 50 hours, about 2 hours to about 4 hours, about 2 hours to about 6 hours, about 2 hours to about 10 hours, about 2 hours to about 20 hours, about 2 hours to about 30 hours, about 2 hours to about 40 hours, about 2 hours to about 50 hours, about 4 hours to about 6 hours, about 4 hours to about 10 hours, about 4 hours to about 20 hours, about 4 hours to about 30 hours, about 4 hours to about 40 hours, about 4 hours to about 50 hours, about 6 hours to about 10 hours, about 6 hours to about 20 hours, about 6 hours to about 30 hours, about 6 hours to about 40 hours, about 6 hours to about 50 hours, about 10 hours to about 20 hours, about 10 hours to about 30 hours, about 10 hours to about 40 hours, about 10 hours to about 50 hours, about 20 hours to about 30 hours, about 20 hours to about 40 hours, about 20 hours to about 50 hours, about 30 hours to about 40 hours, or about 30 hours to about 50 hours.

[0261] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a half-life (T1 / 2) duration of about 4 hours to about 10 hours.

[0262] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a half-life (T1 / 2) duration of about 6 hours to about 8 hours.

[0263] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for at least 3 years.

[0264] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for at least 2 years.

[0265] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for at least 1 year.45321886535vlAttorney Docket No: 254409.000968 PATENT

[0266] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for at least 8 months.

[0267] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for at least 4 months.

[0268] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for at least 3 months.

[0269] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for about 3 months.

[0270] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for at least 2 months.

[0271] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for at least 1 month.

[0272] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for 4-26 weeks.

[0273] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for 8-18 weeks.

[0274] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for 1-90 days.46321886535vlAttorney Docket No: 254409.000968 PATENT

[0275] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for 1-30 days.

[0276] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for 1-10 days.

[0277] In some embodiments, the method comprises administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for 1-5 days.

[0278] In some embodiments, the method treats, reduces, or ameliorates one or more of the symptoms or conditions described herein for at least one week after administration. In some embodiments, the method treats, reduces, or ameliorates the one or more of developmental delays, IDD, intellectual deficits, learning disabilities, anxiety, depression, obsessive- compulsive behaviors, ADD, hyperactivity disorder, aberrant behavior, social and communication deficits, autism spectrum disorder, seizures, insomnia, obesity, and hypotonia for at least one week after administration.Pharmaceutical Compositions of 5-{[5-(3-Chlorophenyl)-6-Methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a Pharmaceutically Acceptable Salt Thereof

[0279] Provided herein is a pharmaceutical composition comprised of 0.05 mg to about 50 mg of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, and pharmaceutically acceptable carriers. The amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof is based on the free form of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine.

[0280] In some embodiments, a pharmaceutical composition comprises about 0.05 mg to about 0.5 mg, about 0.05 mg to about 5 mg, about 0.05 mg to about 10 mg, about 0.05 mg to about 20 mg, about 0.05 mg to about 30 mg, about 0.05 mg to about 40 mg, about 0.05 mg to47321886535vlAttorney Docket No: 254409.000968 PATENT about 50 mg, about 0.1 mg to about 5 mg, about 0.1 mg to about 10 mg, about 0.1 mg to about 20 mg, about 0.1 mg to about 30 mg, about 0.1 mg to about 40 mg, about 0.1 mg to about 50 mg, about 0.5 mg to about 1 mg, about 0.5 mg to about 5 mg, about 0.5 mg to about 10 mg, about 0.5 mg to about 20 mg, about 0.5 mg to about 30 mg, about 0.5 mg to about 40 mg, about 0.5 mg to about 50 mg, about 1 mg to about 5 mg, about 1 mg to about 10 mg, about 1 mg to about 20 mg, about 1 mg to about 30 mg, about 1 mg to about 40 mg, about 1 mg to about 50 mg, about 5 mg to about 10 mg, about 5 mg to about 20 mg, about 5 mg to about 30 mg, about 5 mg to about 40 mg, about 5 mg to about 50 mg, about 10 mg to about 20 mg, about 20 mg to about 30 mg, about 30 mg to about 40 mg, or about 40 mg to about 50 mg of 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.

[0281] In some embodiments, a pharmaceutical composition comprises 0.1 mg to about 5 mg of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and pharmaceutically acceptable earners.

[0282] In some embodiments, the pharmaceutical composition further comprises one or more excipients selected from a diluent, a disintegrant, a glidant, and a lubricant.

[0283] In some embodiments, the diluent is in an amount of about 50% to about 99% (w / w).

[0284] In some embodiments, the diluent is in an amount of about 50% to about 60% (w / w), about 50% to about 70% (w / w), about 50% to about 80% (w / w), about 50% to about 90% (w / w). about 50% to about 94% (w / w), about 50% to about 98% (w / w), about 50% to about 99% (w / w), about 60% to about 70% (w / w), about 60% to about 80% (w / w), about 60% to about 90% (w / w), about 60% to about 94% (w / w), about 60% to about 98% (w / w), about 60% to about 99% (w / w), about 70% to about 80% (w / w), about 70% to about 90% (w / w), about 70% to about 94% (w / w), about 70% to about 98% (w / w), about 70% to about 99% (w / w), about 80% to about 90% (w / w), about 80% to about 94% (w / w), about 80% to about 98% (w / w), about 80% to about 99% (w / w), about 90% to about 94% (w / w), about 90% to about48321886535vlAttorney Docket No: 254409.000968 PATENT98% (w / w), about 90% to about 99% (w / w), about 94% to about 98% (w / w), about 94% to about 99% (w / w), or about 98% to about 99% (w / w).

[0285] bi some embodiments, the diluent is in an amount of about 80% to about 98% (w / w).

[0286] In some embodiments, the diluent is in an amount of about 90% to about 98% (w / w).

[0287] In some embodiments, the diluent is in an amount of about 94% to about 98% (w / w).

[0288] In some embodiments, the diluent is selected from the group consisting of a sugar, dextrates, dextrin, dextrose, lactose, lactose monohydrate, mannitol, sorbitol, starch, cellulose, and modified celluloses, and any combination thereof.

[0289] In some embodiments, the diluent is starch, optionally pregelatinized starch.

[0290] In some embodiments, the disintegrant is in an amount of about 0.1% to about0.2% (w / w), about 0.1% to about 0.5% (w / w), about 0.1% to about 1% (w / w), about 0.1% to about 2% (w / w). about 0.1% to about 3% (w / w), about 0.1% to about 4% (w / w). about 0.1% to about 5% (w / w), about 0.1% to about 8% (w / w), about 0.1% to about 10% (w / w), about 0.2% to about 0.5% (w / w), about 0.2% to about 1% (w / w), about 0.2% to about 2% (w / w), about 0.2% to about 3% (w / w), about 0.2% to about 4% (w / w), about 0.2% to about 5% (w / w), about 0.2% to about 8% (w / w), about 0.2% to about 10% (w / w), about 0.5% to about 1% (w / w), about 0.5% to about 2% (w / w), about 0.5% to about 3% (w / w), about 0.5% to about 4% (w / w). about 0.5% to about 5% (w / w), about 0.5% to about 8% (w / w), about 0.5% to about 10% (w / w), about 1% to about 2% (w / w), about 1% to about 3% (w / w), about 1% to about 4%(w / w), about 1% to about 5% (w / w), about 1% to about 8% (w / w), about 1% to about 10%(w / w), about 2% to about 3% (w / w), about 2% to about 4% (w / w), about 2% to about 5%(w / w), about 2% to about 8% (w / w), about 2% to about 10% (w / w), about 3% to about 4%(w / w), about 3% to about 5% (w / w), about 3% to about 8% (w / w), about 3% to about 10%(w / w), about 4% to about 5% (w / w), about 4% to about 8% (w / w), about 4% to about 10%(w / w), about 5% to about 8% (w / w), about 5% to about 10% (w / w). or about 8% to about 10% (w / w).49321886535vlAttorney Docket No: 254409.000968 PATENT

[0291] In some embodiments, the disintegrant is in an amount of about 0.5% to about 4% (w / w).

[0292] In some embodiments, the disintegrant is in an amount of about 1% to about 3% (w / w).

[0293] In some embodiments, the disintegrant is selected from the group consisting of croscarmellose sodium, crospovidone, starch, sodium starch glycolate, and any combinations thereof.

[0294] In some embodiments, the disintegrant is sodium starch glycolate.

[0295] In some embodiments, the glidant is in an amount of about 0.1% to about 0.2% (w / w), about 0.1% to about 0.5% (w / w), about 0.1% to about 1% (w / w), about 0.1% to about 2% (w / w), about 0.1% to about 3% (w / w), about 0.1% to about 4% (w / w), about 0.1% to about 5% (w / w), about 0.1% to about 8% (w / w). about 0.1% to about 10% (w / w), about 0.2% to about 0.5% (w / w), about 0.2% to about 1% (w / w), about 0.2% to about 2% (w / w), about 0.2% to about 3% (w / w), about 0.2% to about 4% (w / w), about 0.2% to about 5% (w / w), about 0.2% to about 8% (w / w), about 0.2% to about 10% (w / w), about 0.5% to about 1% (w / w), about 0.5% to about 2% (w / w), about 0.5% to about 3% (w / w), about 0.5% to about 4% (w / w), about 0.5% to about 5% (w / w), about 0.5% to about 8% (w / w), about 0.5% to about 10% (w / w), about 1% to about 2% (w / w), about 1% to about 3% (w / w), about 1% to about 4% (w / w), about 1% to about 5% (w / w), about 1% to about 8% (w / w), about 1% to about 10% (w / w), about 2% to about 3% (w / w). about 2% to about 4% (w / w), about 2% to about 5% (w / w). about 2% to about 8% (w / w), about 2% to about 10% (w / w), about 3% to about 4% (w / w), about 3% to about 5% (w / w), about 3% to about 8% (w / w), about 3% to about 10% (w / w), about 4% to about 5% (w / w), about 4% to about 8% (w / w), about 4% to about 10% (w / w), about 5% to about 8% (w / w), about 5% to about 10% (w / w), or about 8% to about 10% (w / w).

[0296] In some embodiments, the glidant is in an amount of about 0.2% to about 1% (w / w).50321886535vlAttorney Docket No: 254409.000968 PATENT

[0297] In some embodiments, the glidant is selected from the group consisting of silicon dioxide, talc, corn starch, and any combinations thereof.

[0298] In some embodiments, the glidant is silicon dioxide, optionally colloidal silicon dioxide.

[0299] In some embodiments, the lubricant is in an amount of about 0.1% to about 0.2% (w / w), about 0.1% to about 0.5% (w / w), about 0.1% to about 1% (w / w), about 0.1% to about 2% (w / w), about 0.1 % to about 3% (w / w), about 0.1 % to about 4% (w / w), about 0.1 % to about 5% (w / w), about 0.1% to about 8% (w / w), about 0.1% to about 10% (w / w), about 0.2% to about 0.5% (w / w). about 0.2% to about 1% (w / w), about 0.2% to about 2% (w / w). about 0.2% to about 3% (w / w), about 0.2% to about 4% (w / w), about 0.2% to about 5% (w / w), about 0.2% to about 8% (w / w), about 0.2% to about 10% (w / w), about 0.5% to about 1% (w / w), about 0.5% to about 2% (w / w), about 0.5% to about 3% (w / w), about 0.5% to about 4% (w / w), about 0.5% to about 5% (w / w), about 0.5% to about 8% (w / w), about 0.5% to about 10% (w / w), about 1% to about 2% (w / w), about 1% to about 3% (w / w), about 1% to about 4% (w / w), about 1% to about 5% (w / w), about 1% to about 8% (w / w), about 1% to about 10% (w / w), about 2% to about 3% (w / w), about 2% to about 4% (w / w), about 2% to about 5% (w / w), about 2% to about 8% (w / w), about 2% to about 10% (w / w), about 3% to about 4% (w / w), about 3% to about 5% (w / w), about 3% to about 8% (w / w), about 3% to about 10% (w / w), about 4% to about 5% (w / w), about 4% to about 8% (w / w), about 4% to about 10% (w / w), about 5% to about 8% (w / w). about 5% to about 10% (w / w), or about 8% to about 10% (w / w).

[0300] In some embodiments, the lubricant is in an amount of about 0.2% to about 1% (w / w).

[0301] In some embodiments, the lubricant is selected from the group consisting of talc, stearic acid, leucine, glyceryl behenate, glyceryl dibehenate, glyceryl palmitostearate, hydrogenated vegetable oil, magnesium stearate, and any combinations thereof.

[0302] In some embodiments, the lubricant is magnesium stearate.51321886535vlAttorney Docket No: 254409.000968 PATENT

[0303] In some embodiments, the pharmaceutical composition comprises about 96% (w / w) starch, about 2% (w / w) sodium starch glycolate, about 0.5% (w / w) silicon dioxide, and about 0.5% (w / w) magnesium stearate.

[0304] In some embodiments, the pharmaceutical composition is an oral dosage form.

[0305] In some embodiments, the pharmaceutical composition is a solid form.

[0306] In some embodiments, the pharmaceutical composition is in the form of a tablet, capsule, caplet, pill, granule, powder, lozenge, troche, or suppository.

[0307] In some embodiments, the pharmaceutical composition is in the form of a capsule.

[0308] In some embodiments, the pharmaceutical composition comprises about 0.5 mg of5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof. The amount of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl]pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, is based on free form 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2- amine in the present disclosure.

[0309] In some embodiments, the pharmaceutical composition comprises about 2 mg of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0310] In some embodiments, the pharmaceutical composition comprises about 2.5 mg of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0311] In some embodiments, the pharmaceutical composition comprises about 3 mg of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof.

[0312] In some embodiments, the pharmaceutical composition comprises about 5 mg of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof.52321886535vlAttorney Docket No: 254409.000968 PATENT

[0313] In some embodiments, the pharmaceutical composition comprises about 7.5 mg of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0314] In some embodiments, the pharmaceutical composition comprises about 10 mg of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0315] In some embodiments, the pharmaceutical composition comprises about 12.5 mg of 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0316] In some embodiments, the pharmaceutical composition comprises about 15 mg of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof.

[0317] In some embodiments, the pharmaceutical composition comprises about 0.05 mg, about 0.1 mg, about 0.2 mg, about 0.3 mg, about 0.5 mg, about 1 mg, about 1.5 mg, about 2 mg, about 2.5 mg, about 3 mg, about 3.5 mg, about 4 mg, about 4.5 mg, about 5 mg, about 5.5 mg, about 6 mg, about 7 mg, about 7.5 mg, about 8 mg, about 9 mg, about 10 mg, about 12.5 mg, about 15 mg, about 17.5 mg, about 20 mg, about 22.5 mg, about 25 mg, about 27.5 mg, about 30 mg, about 32.5 mg, about 35 mg, about 37.5 mg, about 40 mg, about 42.5 mg, about 45 mg, about 47.5 mg, or about 50 mg of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl]pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0318] In some embodiments, the total weight of the pharmaceutical composition is about 50 mg to about 5000 mg.

[0319] In some embodiments, the total weight of the pharmaceutical composition is about 50 mg to about 75 mg, about 50 mg to about 100 mg, about 50 mg to about 150 mg, about 50 mg to about 200 mg, about 50 mg to about 250 mg, about 50 mg to about 300 mg, about 50 mg to about 400 mg, about 50 mg to about 500 mg, about 50 mg to about 700 mg, about 50 mg to about 1000 mg, about 50 mg to about 2000 mg, about 50 mg to about 3000 mg,53321886535vlAttorney Docket No: 254409.000968 PATENT about 50 mg to about 5000 mg, about 75 mg to about 100 mg, about 75 mg to about 150 mg, about 75 mg to about 200 mg, about 75 mg to about 250 mg, about 75 mg to about 300 mg, about 75 mg to about 400 mg, about 75 mg to about 500 mg, about 75 mg to about 700 mg, about 75 mg to about 1000 mg, about 75 mg to about 2000 mg, about 75 mg to about 3000 mg, about 75 mg to about 5000 mg, about 100 mg to about 150 mg, about 100 mg to about 200 mg, about 100 mg to250 mg, about 100 mg to about 300 mg, about 100 mg to about 400 mg, about 100 mg to about 500 mg, about 100 mg to about 700 mg, about 100 mg to about 1000 mg, about 100 mg to about 2000 mg, about 100 mg to about 3000 mg, about 100 mg to about 5000 mg, about 150 mg to about 200 mg, about 150 mg to about 250 mg, about 150 mg to about 300 mg, about 150 mg to about 400 mg, about 150 mg to about 500 mg, about 150 mg to about 700 mg, about 150 mg to about 1000 mg, about 150 mg to about 2000 mg, about 150 mg to about 3000 mg, about 150 mg to about 5000 mg, about 200 mg to about 250 mg, about 200 mg to about 300 mg, about 200 mg to about 400 mg, about 200 mg to about 500 mg, about 200 mg to about 700 mg, about 200 mg to about 1000 mg, about 200 mg to about 2000 mg, about 200 mg to about 3000 mg, about 200 mg to about 5000 mg, about 250 mg to about 300 mg, about 250 mg to about 400 mg, about 250 mg to about 500 mg, about 250 mg to about 700 mg, about 250 mg to about 1000 mg, about 250 mg to about 2000 mg, about 250 mg to about 3000 mg, about 250 mg to about 5000 mg, about 300 mg to about 400 mg, about 300 mg to about 500 mg, about 300 mg to about 700 mg, about 300 mg to about 1000 mg, about 300 mg to about 2000 mg, about 300 mg to about 3000 mg, about 300 mg to about 5000 mg, about 400 mg to about 500 mg, about 400 mg to about 700 mg, about 400 mg to about 1000 mg, about 400 mg to about 2000 mg, about 400 mg to about 3000 mg, about 400 mg to about 5000 mg, about 500 mg to about 700 mg, about 500 mg to about 1000 mg, about 500 mg to about 2000 mg, about 500 mg to about 3000 mg, about 500 mg to about 5000 mg, about 700 mg to about 1000 mg, about 700 mg to about 2000 mg, about 700 mg to about 3000 mg, about 700 mg to about 5000 mg, about 1000 mg to about 2000 mg, about 1000 mg to about 3000 mg, about 1000 mg to54321886535vlAttorney Docket No: 254409.000968 PATENT about 5000 mg, about 2000 mg to about 3000 mg, about 2000 mg to about 5000 mg, or about 3000 mg to about 5000 mg.

[0320] In some embodiments, the total weight of the pharmaceutical composition is between about 50 mg to about 500 mg.

[0321] In some embodiments, the total weight of the pharmaceutical composition is between about 250 mg to about 400 mg.

[0322] In some embodiments, the total weight of the pharmaceutical composition is about 335 mg.

[0323] In some embodiments, the administration is oral administration.

[0324] In some embodiments, the method described above comprises administering a pharmaceutical composition, as described herein, comprising 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl]pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof.

[0325] Training protocols are generally employed in rehabilitating individuals who have some form and degree of cognitive or motor dysfunction. For example, training protocols are employed in FXS patients to address cognitive, behavioral, or motor skill challenges, as well as other issues.

[0326] Training generally requires multiple sessions to attain the desired benefits. This can be costly and time-consuming, deterring subject compliance and the realization of benefits that endure over time. The efficiency of such training protocols can be improved by administering certain agents (known as augmenting agents) in conjunction with the training protocol. The use of augmenting agents achieves cognitive training effects with less repetition, i.e., fewer training sessions.

[0327] In certain embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof is used as an augmenting agent in methods to enhance the efficiency of cognitive or motor training for FXS patients.55321886535vlAttorney Docket No: 254409.000968 PATENT

[0328] In some embodiments, the method described above comprises administering 5- { [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, or the pharmaceutical composition described above in combination with a training protocol.

[0329] In some embodiments, the training protocol is cognitive training, motor training, occupational training, language training, or other behavioral intervention.

[0330] Cognitive training protocols can be directed to numerous cognitive dimensions, including memory, concentration and attention, perception, learning, planning, sequencing, and judgment. Motor training protocols can be directed to numerous motor domains, such as the rehabilitation of arm or leg function after a stroke or head injury. One or more protocols (or modules) underling a training program can be provided to a subject.Kits for Treating FXS with an Instruction for Administration with Food

[0331] Provided herein is a kit for treating FXS comprises 5-{[5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl)pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and an instruction for administration with food.

[0332] In some embodiments, 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is present as a pharmaceutical dosage form.

[0333] In some embodiments, the dosage form comprises about 0.1 mg to about 5 mg of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl]pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

[0334] In some embodiments, the dosage form is a tablet, capsule, caplet, pill, granule, powder, lozenge, troche, or suppository.

[0335] In some embodiments, the dosage form is a capsule.

[0336] In some embodiments, the food comprises high-calorie food.

[0337] In some embodiments, the food comprises high-protein food.56321886535vlAttorney Docket No: 254409.000968 PATENTEXAMPLES

[0338] The following examples are provided to further describe some of the embodiments disclosed herein. The examples are intended to illustrate, not to limit, the disclosed embodiments.Example 1. Comparative Studies of MRM-3379, Zatolmilast (BPN14770) and Roflumilast1.1 Memory-Enhancing Effects

[0339] The memory-enhancing effects of MRM-3379 were studied in an animal model of cognition: an object location task. This task allowed the assessment of consolidation of (object) information into memory (e.g., Ennaceur and Delacour, 1988; Prickaerts et al., 1997). In this task, a rat had to perform two trials. In the first trial (Tl), a rat was put into an arena in which two identical objects were placed in the arena in a symmetrical manner. Rats inspected these two objects for a certain amount of time. After a specific delay, the rats performed a second trial (T2). hi this second trial, the rats were again placed in the same arena, but now, one of the objects had been moved to a different location. Similar to the first trial, the rats again explored the two objects. By scoring how much time the rats inspected the two objects, it can be determined whether the rats spent a different amount of time exploring the moved vs. the nonmoved object, and based on this difference, memory performance can be determined.

[0340] The effects of MRM-3379, zatolmilast (BPN 14770), and roflumilast (positive control) on time-dependent forgetting (in a 24-hour inter-trial interval) were studied in rats. All drugs were injected p.o. (2 ml / kg) 3 hours after the first trial to investigate the effects on late memory consolidation. MRM-3379 was tested at doses of 0.03, 0.1, and 0.3 mg / kg, whereas BPN 14770 was tested at doses of 0.01, 0.03, 0.1, 0.3, 1, and 3 mg / kg. Roflumilast was tested at a dose of 0.3 mg / kg.

[0341] The basic measures were the times spent by rats exploring an object during Tl and T2. The time spent exploring the two objects in Tl was represented by ‘al’ and ‘a2’. The time spent in T2 exploring the moved and non-moved objects was represented by ‘a3’ and ‘b,’57321886535vlAttorney Docket No: 254409.000968 PATENT respectively. The following variables were calculated: el = al + a2, e2 = a3 + b, and DI = (b - a3) / e2. el and e2 are measures of the total exploration time of both objects during T1 and T2, respectively. DI stands for discrimination index (DI). DI is a relative measure of discrimination corrected for exploratory activity in the test trials. The larger the DI, the higher the degree to which the compounds were able to attenuate the time-induced object memory deficit. The compounds were given to 2-month-old male Wistar rats. At the end of the studies, post-decapitation trunk blood and whole-brain samples were collected from the animals for determination of post-dose brain and plasma concentrations.

[0342] Figure 1 shows the DI graph for MRM-3379 administered and tested at doses of 0.01, 0.03, 0.1, and 0.3 mg / kg (the control of placebo was represented at 0.0 mg / kg) and the post-dose brain and plasma concentrations. Figure 2 shows the DI graphs as a function of the brain and plasma concentration of MRM-3379 (0.03, 0.1, and 0.3 mg / kg ) relative to BPN14770 (0.01, 0.03, 0.1, 0.3, 1, and 3 mg / kg). MRM-3379 and BPN14770 had similar efficacy at the same brain concentrations. MRM-3379 was effective at much lower plasma concentrations, affording a lower risk of gastrointestinal (GI) and immune-related side effects. Figure 3 shows the plasma concentration (Cp) and the brain concentration (Cb) of MRM-3379 at 0.3 mg / kg as a function of the time duration after administration. Figure 4A shows the brain-to-plasma concentration ratio for MRM-3379, BPN14770, and roflumilast for rats (studied above), mice, and primates. To achieve the same EC in the brain, the plasma concentration of MRM-3379 is much lower than BPN14770 or Roflumilast.1.2. Emesis Evaluation Studies

[0343] Ferrets (rather than rats) were used to assess vomiting, because ferrets have a well- developed vomiting reflex, whereas rats lack such reflex. The ferret's emetic pathways also have anatomical and physiological similarities to those of humans.

[0344] Fasted male ferrets (n = 4) were administered a single oral dose of MRM-3379 (1 or 3 mg / kg). Animals were observed for emesis up to 1 hour post-dose, then plasma and brains were obtained for MRM-3379 analysis. Three of four animals administered 3 mg / kg showed58321886535vlAttorney Docket No: 254409.000968 PATENT signs of emesis while there were no emesis events recorded for the animals administered 1 mg / kg. The mean plasma and brain concentration of MRM-3379 at 60 minutes post-dose following oral dose at 1.0 mg / kg were 68 ng / mL (208 nM) and 75 ng / g (230 nM), respectively. The brain-to-plasma ratio (B / P) was 1.11 in ferrets.

[0345] The emetic window is determined by the ratio (fold-difference) of the plasma concentration, brain concentration, or total plasma exposure (AUC) in ferrets showing emetic response (ferrets being administered at emesis-causing dose) to the corresponding plasma concentration, brain concentration, or AUC in rats (rats being administered at ED) (Table 1A). A greater number for the emetic window indicates a reduced emesis rate or severity level (Figure 4B). MRM-3379 was shown to provide a reduced emesis rate or severity level than roflumilast.Table 1A. Emetic Window for Roflumilast and MRM-33791.3. Comparative Binding Affinities of MRM-3379 and BPN14770 in Rat Brain Homogenates

[0346] The binding affinities of the PDE4 inhibitors MRM-3379 and BPN14770 were evaluated in brain homogenate competition binding assays using the PDE4 targeting radiotracer [3H]R-Rolipram. The results, as described below, show a stronger binding affinity of MRM-3379 compared to BPN 14770.59321886535vlAttorney Docket No: 254409.000968 PATENTMethods

[0347] Brain homogenate preparation: Sprague-Dawley rat brains without cerebellum were weighed and homogenized in a sucrose-rich buffer (0.32 M sucrose, 50 mM Tris, 1 mM MgCh, pH 7.4, 4°C) followed by centrifugation at low speed (1000 x g) at 4°C for 10 minutes. The pellets were washed and the supernatants were pooled together and centrifuged at high speed (32,000 x g) at 4°C for 20 minutes to produce P2 pellets. The P2 pellets were washed four times to obtain P2 membrane homogenates. Homogenate protein concentrations were determined by the Bicinchoninic Acid (BCA) method (Pierce) and the homogenates were stored at -80°C until needed.Saturation Binding Assay

[0348] The P2 brain homogenate was thawed on ice and prepared using extracellular assay buffer (50 mM Tris, 140 mM NaCl. 1.5 mM MgC12, 5 mM KC1. 1.5 mM CaC12, pH 7.4, 23 °C) to an assay volume of 0.5 ml per well with ~ 300 pg / well protein. Homogenate suspensions were incubated at 37°C for 60 min with 8 concentrations (0.3 - 100 nM) of [3H](R)-Rolipram. The specific binding component was determined by incubating the membrane suspension at room temperature in the presence of radioligand with a saturating concentration of homologous blocking compound (10 pM (R)-Rolipram) to yield a measure of non-specific binding. Assays were terminated by filtration through Whatman GF / C filters and washed with ice-cold wash buffer (50 mM Tris, 1.4 mM MgC12, pH 7.4, 4 °C). A second assay was prepared as above without the addition of protein homogenate in order to determine the filter binding.Homologous Competition Binding Assay

[0349] P2 brain homogenates were prepared in extracellular assay buffer (50 mM Tris, 140 mM NaCl, 1.5 mM MgC12, 5 mM KC1, 1.5 mM CaC12, pH 7.4, 23 °C) to a concentration of -300 pg / ml protein and incubated with 2 nM [3H](R)-Rolipram in the presence of increasing concentrations of unlabeled (R)-Rolipram (0.01 nM - 5 pM) at 37°C for 60 minutes. The specific binding component was determined by incubating the membrane suspension in the60321886535vlAttorney Docket No: 254409.000968 PATENT presence of radioligand with a saturating concentration of homologous blocking compound (10 pM (R)-Rolipram) to yield a measure of non-specific binding. Assays were terminated by filtration through Whatman GF / C filters and washed with ice-cold wash buffer (50 mM Tris, 1.4 mM MgC12, pH 7.4, 4°C). Data for each unlabeled (R)-Rolipram concentration was expressed as a percentage of total binding and specific binding in the absence of unlabeled (R)-Rolipram.Heterologous Competition Binding Assay

[0350] P2 brain homogenates were prepared in extracellular assay buffer (50 mM Tris, 140 mM NaCl, 1.5 mM MgCh, 5 mM KC1, 1.5 mM CaC12, pH 7.4, 23 °C) to a concentration of -300 pg / ml protein and incubated with 3 nM [3H](R)-Rolipram in the presence of increasing concentrations of either BPN14770 (0.1 nM - 5 pM) or MRM- 3379 (0.01 nM - 5 pM) at 37°C for 60 minutes. The specific binding component was determined by incubating the membrane suspension in the presence of radioligand with a saturating concentration of homologous blocking compound (10 pM (R)-Rolipram) to yield a measure of non-specific binding. Assays were terminated by filtration through Whatman GF / C filters and washed with ice-cold wash buffer (50 mM Tris, 1.4 mM MgCh, pH 7.4, 4°C). Data for each unlabeled (R)- Rolipram concentration was expressed as a percentage of total binding and specific binding in the absence of unlabeled (R)-RolipramResults

[0351] Assay conditions were first optimized in a saturation homogenate binding assay, which established specific binding (> 90%) of 1 to 100 nM [3H](R)-Rolipram, an estimated binding affinity (KD) of 8.60 ± 0.67 nM for [3H](R)-Rolipram, and a maximal number of binding sites (BMAX) of 900.2 ± 19.6 fmol / mg protein.

[0352] A homologous competition binding assay was then performed using - 2 nM [3H](R)- Rolipram with 0.1 nM to 5 pM of unlabeled (R)-Rolipram, which indicated a specific binding affinity (Ki) of 1.68 ± 0.07 nM. The binding parameters are summarized in Table IB.Table IB. Parameters of (R)-Rolipram Homologous Competition Binding 61321886535vlAttorney Docket No: 254409.000968 PATENT

[0353] With these assay conditions confirmed, heterologous competition binding assays were then performed with MRM-3379 or BPB- 14770.

[0354] Heterologous competition binding assay with BPN14770: the homogenate competition binding assay (n=3 independent assays) was performed using 3 nM [3H](R)- Rolipram with 0.1 nM - 5 M of BPN14770. Over the concentration range tested, BPN14770 showed progressive displacement of the radioligand with 6-100% of total binding observed.Using the specific binding signal to determine binding parameters, the binding affinity (Ki) of BPN14770 was determined to be 61.4 ± 21 nM. The binding parameters are summarized in Table 1C.Table 1C. Parameters of BPN14770 Heterologous Competition Binding62321886535vlAttorney Docket No: 254409.000968 PATENT

[0355] Heterologous competition binding assay with MRM-3379: the homogenate competition binding assay (n=3 independent assays) was initially performed using 3 nM [3H](R)-Rolipram with 0.1 nM - 5 pM of MRM-3379. At 0.1 nM MRM-3379, binding only reached -65% of total binding, indicating significant displacement of the radioligand.Subsequently, the assay was repeated on a fourth independent study day using a lower range of MRM-3379 (0.01 nM - 1 pM). In this fourth assay, binding reached up to 80% of total binding.

[0356] When data from all four competition assay days were combined, the binding affinity (Ki) of MRM-3379 was determined to be 13.44 + 12 nM. The binding parameters are summarized in Table ID.Table ID. Parameters of MRM-3379 Heterologous Competition BindingSummary

[0357] Competition binding assays in rat brain homogenates, using [3H](R)-Rolipram, indicated a higher binding affinity (i.e., a lower Ki) for MRM-3379 compared to BPN- 14770.63321886535vlAttorney Docket No: 254409.000968 PATENTThe specific mean Ki value of MRM-3379 (13.44 nM) was substantially lower than the specific mean Ki value of BPN14770 (61.41 nM).1.4. Suppression of Cytokine Responses by BPN14770 but not MRM-3379 at Therapeutic Plasma Concentrations

[0358] MRM-3379 and BPN 14770 were evaluated in whole blood LPS stimulation experiments to generate concentration response curves with respect to cytokine release. The response curves were then used to predict whether BPN- 14770 or MRM-3379 would inhibit cytokine responses at their expected therapeutically efficacious plasma concentrations. Based on this analysis, BPN14770 - but not MRM-3379 - is predicted to significantly suppress cytokine responses at its corresponding therapeutic plasma exposure.MethodsLPS stimulation

[0359] LPS stimulation experiments were performed in whole blood to determine the LPS ECso value to use for stimulation in compound treatment experiments. Three blood donors were used per experiment. Blood was transferred from vacutainers to 50 mL centrifuge tubes and diluted 1:1 with assay media (DMEM + 10% FBS), and 100 pL / well of diluted blood was dispensed into 96-well assay plates.

[0360] Three separate batches of LPS (O127:B8, O55:B5, O26:B6) were prepared in assay media at 2X concentration, in an 8-point 3-fold dilution series with a 300 ng / mL top final assay concentration (FAC). 100 pL of each LPS dilution series was added in triplicate to the plates. 100 pL of assay media only was added in triplicate for non-stimulated controls.

[0361] Plates were incubated for a total of 24 hours at 37 °C (5% CO2), with supernatant samples obtained at 4, 6 and 24 hours and stored at -20°C for subsequent AlphaLISA analysis. Following AlphaLISA analysis, the incubation period and the LPS stimulation concentration (LPS EC80) were determined for use in subsequent compound experiments.Compound treatment64321886535vlAttorney Docket No: 254409.000968 PATENT

[0362] As above, 100 pL / well of diluted blood was dispensed into 96 well assay plates.Compounds were dispensed directly to wells using the MultiDrop Pico 8 to achieve the concentration series shown in Table IE. DMSO (vehicle) was added to control wells.Table IE. Compound Concentrations Tested in Whole Blood Assays

[0363] After 1 hour compound pre-incubation, each sample was stimulated with 20 ng / mL FAC LPS O26:B6 for 4 hours at 37°C (5% CO2), with assay media added only to non-LPS control wells. Following incubation, the Agilent Bravo automated liquid handling platform was used to collect and transfer supernatants to a 384 well storage plate, which was stored at - 20 until AlphaLISAs were performed.AlphaLISAs

[0364] The supernatants were assayed for levels of four cytokines: TNF-a, CXCL10, CCL2, and IFN-y, using AlphaLISA technology. Supernatants were diluted 1:5 with assay media using the Agilent Bravo; and 4 pL of sample was dispensed into 384 well plates (one plate per cytokine) using the Agilent Bravo, with 4 pL Acceptor beads and anti-analyte antibody mix added per well using the Certus Flex. Plates were sealed and incubated overnight at 4°C. The following day, plates were equilibrated to room temperature prior to the addition of 2 pL streptavidin-donor bead mix to each well using the Certus Flex. Plates were incubated for 1 hour at room temperature before being read with the PHERAstar FSX (AlphaLISA module). Standard curves were run alongside samples for interpolation of cytokine concentration at each compound concentration point.Data analysis65321886535vlAttorney Docket No: 254409.000968 PATENT

[0365] Data was analyzed using GraphPad Prism 9. Data was plotted for each concentration, with exclusion of data points outside of mean + / - 3 standard deviations. For compound testing experiments, data from all 3 donors were combined to generate 1 concentration-response curve per compound per readout, with results normalized to LPS treated and non-treated controls, and presented as percentage response (%).ResultsLPS stimulation

[0366] For the whole blood assay, all donors produced concentration-dependent TNF-a and CXCL10 responses with all 3 LPS batches at all 3-time points. (CCL2 AlphaLISAs were not included in this study.) No concentration-response curves were seen for any LPS batches for IFNy, which was subsequently excluded from further experiments. LPS O26:B6 was selected as the batch with the highest assay window in CXCL10 while maintaining a good window with the TNF-a readout. LPS ECso values were calculated for each donor for TNF-a and CXCL10 readouts measured at the 4 hour incubation timepoint. An amount of 20 ng / mL LPS O26:B6 was used for stimulation to allow suitable assay windows in both TNF-a and CXCL10 for testing compound inhibition in the whole blood assay.Test compounds

[0367] The test compounds MRM-3379 and BPN14770 (as well as dexamethasone and roflumilast) were each evaluated in the whole blood LPS assay to determine concentration responses for TNFa, CXCL10 and CCL2. All 4 compounds inhibited TNF-a, CXCL10 and CCL2 responses, with roflumilast and MRM-3379 producing full concentration-response curves.

[0368] Figure 4C shows the concentration response curves for TNFa and CXCL10. It also shows, juxtaposed as vertical lines on the curves, expected efficacious plasma concentrations (Cp) for MRM-3379 and BPN14770. The selected Cp for MRM-3379 (< 10 nM) is consistent with the observations - including those in Examples 7 and 8 - that MRM-3379 therapeutic efficacy is present at low doses of 0.5 mg or 1 mg / day. For example, at a dose of 1 mg / day,66321886535vlAttorney Docket No: 254409.000968 PATENT observed MRM-3379 plasma levels do not exceed ~1.5 ng / ml, corresponding to a concentration of - 5 nM. The selected Cp for BPN14770 (> 1 pM) reflects observed mean plasma levels of 535 ng / ml in FXS patients showing positive responses in clinical studies, a level corresponding to a concentration of -1300 nM. See Berry Kravitz et al. 2021, Nat. Med. 27, 862-870. At their corresponding Cplevels, MRM-3379 shows minimal effects on cytokine suppression, whereas BPN14770 shows significant effects on cytokine suppression. (This difference was also seen in concentration response curves for CCL2).Summary

[0369] At expected therapeutic plasma exposures, MRM-3379 is predicted to show minimal suppressive effects on peripheral immune cytokine responses, whereas BPN14770 is predicted to show significant suppressive effects.Example 2. Short-Term Memory Effects in Novel Object Recognition (NOR) Studies

[0370] This study characterized the short-term memory effects of MRM-3379 in a scopolamine-impaired object recognition paradigm.Biological Material

[0371] Sprague-Dawley-derived male rats (175-200g; Envigo, CA) were housed in groups of two or three and maintained in a temperature-controlled environment on a 12h:12h light cycle (0700h on - 1900h off). Except during behavioral testing (0800h-1800h), animals were given free access to food and water. Animals used were handled, housed, and sacrificed in accordance with the current NIH guidelines regarding the use and care of laboratory animals and all applicable local, state, and federal regulations and guidelines. Animals were handled daily for several days to desensitize them to handling stress before behavioral testing. The cell sizes (n=12) provided reliable estimates of treatment effects. Animals were identified by cage number and by numbers applied to the proximal tip of the tail using a “Sharpie” permanent marker.Novel Object Recognition (NOR) Apparatus67321886535vlAttorney Docket No: 254409.000968 PATENT

[0372] The apparatus consisted of an open box made of black ABS (52 cm L; 52 cm W; 31 cm H). The walls of the box were black, and the objects to be discriminated were made of plastic. The objects were positioned in opposite comers and were secured to the apparatus with Velcro to prevent displacement by the animals. After each trial, 30% alcohol was used to clean the objects and box to remove any lingering olfactory cues.Habituation

[0373] During the week prior to the first behavioral testing procedure, all rats were handled to allow habituation to human handling. On the day prior to testing, rats were given a 30- minute exploration period in the NOR box to ensure habituation to the empty apparatus and test room environment.Behavioral Testing

[0374] In the novel object recognition task, each rat was placed into the box and exposed to two identical objects (Al and A2) for a period of 4 minutes. The rats were then returned to their home cage for a 1-hour inter-trial interval, during which the entire box was cleaned, both objects removed, and one replaced with an identical familiar copy and one with a novel object. Following the 1-hour inter- trial interval, rats were returned to explore the familiar and novel object (B) in the test box for a 4-minute retention trial. The location of the novel object in the retention trial was randomly assigned for each rat and counterbalanced within groups. All experiments were video-recorded for subsequent behavioral analysis.

[0375] Object exploration was defined as the rats sniffing, licking, or touching the objects with their forepaws. Leaning against, turning around, or standing on and rearing above the objects was not recorded as exploration. The exploration time of each object in each trial was recorded manually using two stopwatches, and the total exploration time of both objects in the retention trial was calculated. At the commencement of the experiment and during the grading of exploration time, the tester was blinded to the test doses.Treatments68321886535vlAttorney Docket No: 254409.000968 PATENT

[0376] Treatment groups included (pretreatment-treatment) below. 1% carboxymethylcellulose sodium is the vehicle (CMC-Na, mv).Study 1:Vehicle - Vehicle (n=12)Vehicle - Scopolamine, 1 mg / kg (n=12)MRM-3379, 0.01 mg / kg - Scopolamine, 1 mg / kg (n=12) MRM-3379, 0.03 mg / kg - Scopolamine, 1 mg / kg (n= 12) MRM-3379, 0.1 mg / kg - Scopolamine, 1 mg / kg (n=12) Donepezil, 1 mg / kg - Scopolamine. 1 mg / kg (n=12) Study 2:Vehicle - Vehicle (n=12)Vehicle - Scopolamine, 1 mg / kg (n=12)MRM-3379, 0.01 mg / kg - Scopolamine, 1 mg / kg (n=12)MRM-3379, 0.001 mg / kg - Scopolamine, 1 mg / kg (n=12) MRM-3379, 0.0001 mg / kg - Scopolamine, 1 mg / kg (n=12) Donepezil, 1 mg / kg - Scopolamine, 1 mg / kg (n=12) Data Analysis

[0377] Tests for homogeneity of variance were first performed on the data. If the scores did not violate the assumption of homogeneity of variance, appropriate analyses of variance (ANOVA) were performed. The data were expressed as mean ± S.E.M. Discrimination Index (i.e., time exploring novel object (N) - time exploring familiar object (F) / time exploring novel object + time exploring familiar object). Data were analyzed using the GraphPad Prism (v7.03) statistical software. A one-way ANOVA was used with treatment groups as between- subjects independent variable factor(s) and Discrimination Index (DI) as dependent variable factors. Where appropriate, post-hoc analysis was conducted using Dunnett’s multiple comparison test.69321886535vlAttorney Docket No: 254409.000968 PATENT

[0378] Figure 5 shows the effects of MRM-3379 on scopolamine-induced object recognition memory impairment using a 1-h inter-trial interval (ITI). Acute treatment with 1.0 mg / kg scopolamine significantly impaired object recognition memory performance.Pretreatment with MRM-3379 at all doses tested (including low dose levels at 0.001 mg / kg and 0.01 mg / kg) induced a significant improvement in performance compared with scopolamine alone. Donepezil (D( 1); 1.0 mg / kg) pretreatment significantly improved object recognition performance compared with scopolamine alone (N=12 per treatment group). *p < 0.05 vs. VEH-Scopolamine. Pretreatment with MRM-3379 (0.001 - 0.1 mg / kg p.o. as well as the positive control donepezil (1 mg / kg z.p.), significantly attenuated the scopolamine-induced working memory deficit.Example 3. Long-Term Memory Effects in Novel Ob ject Recognition (NOR) Studies

[0379] MRM-3379 was evaluated to enhance long-term memory formation in mice using novel object recognition (NOR) tasks. Novel object recognition is a recognition memory task based on the spontaneous tendency of rodents to spend more time exploring a novel object than a familiar one. Recognition (memory) of a familiar object will cause the animal to preferentially spend more time exploring a new, unfamiliar object.3.1. Mouse Novel Object Recognition - Acute Dose

[0380] MRM-3379 was evaluated in the mouse for enhancement of long-term memory in the NOR task after a single oral dose. Single (acute) treatments were administered 60 minutes prior to training, and then mice were allowed to explore the behavioral arena for 3 minutes, a subthreshold training time that did not result in long-term memory, or for 15 minutes, a maximal training time that resulted in long-term memory formation, measured 24 hours after training. A discrimination index [DI; where DI = (time novel - time familiar) / (time novel + time familiar)], where t = time (seconds) spent exploring, was calculated.

[0381] As shown in Figure 6, mice given a single oral administration of 0.03 mg / kg MRM-3379 60 minutes prior to submaximal training exhibited a significantly greater70321886535vlAttorney Docket No: 254409.000968 PATENT preference for the novel object compared to vehicle-treated mice at the 24-hour retention test. Vehicle-treated mice that received the maximal training (15 minutes) exhibited a greater preference for the novel object compared to the submaximally trained vehicle-treated animals.3.2. Mouse Novel Object Recognition - Repeat Dose

[0382] Mice were orally dosed once daily for four days with vehicle or MRM-3379 (0.01, 0.03, or 0.1 mg / kg) and tested in the NOR assay as described above in Section 3.1. On Day 4, mice were dosed 60 minutes before being placed into the behavioral arena and were allowed to explore for a subthreshold training time of 3 minutes or for 15 minutes, a maximal training time that results in long-term memory formation. Twenty-four hours after completion of training, long-term memory was evaluated, and the amount of time spent interacting with each object and calculating a DI was recorded.

[0383] As seen in Figure 7, mice treated once daily for four (4) days with 0.1 mg / kg MRM-3379 exhibited a significantly greater preference for the novel object compared to vehicle-treated mice at the 24-hour retention test. Vehicle-treated mice that received maximal training (15 minutes) exhibited a greater preference for the novel object compared to the submaximally trained vehicle-treated animals.

[0384] Together, these data show that dosed once or repeatedly (once daily for 4 days) enhanced long-term object recognition memory in mice.Example 4. Memory Enhancement in Rats

[0385] Contextual fear conditioning (CFC) is an associative learning task in which a contextual conditioned stimulus is paired with an aversive unconditioned stimulus (e.g., foot shock). In rodents, conditioned fear was measured by the amount of freezing behavior (an innate response to fear) exhibited in the trained context while in the absence of foot shock.

[0386] MRM-3379 was tested for its ability to enhance memory of the association between the context and aversive stimulus when paired with submaximal training, which by itself produces submaximal 24-hour memory. Submaximal training consisted of two foot shocks (2US); maximal training which produced long-lasting memory of the association71321886535vlAttorney Docket No: 254409.000968 PATENT(measured 24 hours after training) was produced by 5 foot shocks (5US). Animals were dosed with MRM-3379 (0.01, 0.03, or 0.1 mg / kg; p.o.) or vehicle and then submaximally trained 60 minutes postdose (2US). A separate group of rats was dosed with the vehicle, followed by maximal training (5US) one hour later. Twenty-four hours after training, animals were tested (drug-free) in the same chamber (i.e., context) for 3 minutes. Memory for the foot shock- paired context was assessed by the amount of freezing behavior observed during the test period. Freezing was defined as the absence of movement, with the exception of respiration, using automated software.

[0387] As shown in Figure 8, rats treated with 0.03 mg / kg p.o. MRM-3379 exhibited a higher mean percent freezing score compared to the 2US vehicle-treated rats (p < 0.05). The vehicle group that received maximal training also exhibited higher percent freezing scores for the foot shock-paired context compared to the vehicle group that received only submaximal training (p < 0.001). Thus, administering MRM-3379 reduces the amount of training needed to attain maximal performance (e.g., memory).

[0388] Plasma exposure was measured in rats at the 0.03 mg / kg p.o. minimum effective MRM-3379 dose that produces long-term memory formation. Mean MRM-3379 plasma exposure (area under the concentration-time curve [AUC] from time zero (0) to infinity [AUCco]) was 1.51 ng-h / mL. Mean maximum observed plasma concentration (Cmax) was 0.082 ng / mL. In contrast, the Cmax for roflumilast is 0.37 ng / ml and Cmax for BPN14770 is 70- 150ng / mL. This shows that MRM-3379 was effective at much lower plasma concentrations than BPN14770 or roflumilast.Example 5. Pharmacokinetics, Absorption, Distribution, Metabolism and Excretion5.1. Absorption and Pharmacokinetics (PK) in Animals

[0389] The PK profile of MRM-3379 was evaluated after single and repeat dosing in rats and monkeys.5.1.1. Single Dose Pharmacokinetics5.1.1.1. Single-Dose Pharmacokinetics / Toxicokinetics in Sprague Dawley Rats72321886535vlAttorney Docket No: 254409.000968 PATENT

[0390] Single oral administration of MRM-3379 was studied from 0.03 mg / kg to 200 mg / kg in the rat. The mean time of observed maximal plasma concentration (Tmax) at lower dose levels (0.03 to 5 mg / kg) occurred at approximately 0.5 to 2.38 hours post-dose. Subsequent elimination occurred shortly after Tmaxwas achieved, and mean half-life (T1 / 2) values were approximately 1.17 to 2.43 hours. The observed T1 / 2 increased at higher dose levels with values up to at least 20 hours. This prolonged absorption phase and non-linear elimination suggested that clearance becomes saturated or inhibited at higher dose levels.

[0391] Absolute oral bioavailability after a p.o. dose of 0.03 mg / kg formulated in PEG400: water (50 / 50), a dose level and formulation associated with efficacy in the rat, was 12.0%. Increases in mean exposure to MRM-3379 were generally greater than or equal to dose proportional from 0.03 mg / kg up to about 20 mg / kg and less than dose-proportional at higher dose levels. Mean Cmax values followed similar trends. Absorption appeared to plateau at 60 mg / kg after a single oral dose.

[0392] Hepatic extraction was assessed in separate groups of jugular vein catheterized and portal vein catheterized rats, orally administered 5 mg / kg MRM-3379 formulated in 1% carboxymethylcellulose. Comparison of the exposure AUCo-tto MRM-3379 between the portal (2840 ± 260 ng-h / mL) and systemic (1657 ± 451 ng-h / mL) circulation demonstrated a moderate first-pass hepatic extraction of 42% at this dose level.5.1.1.2. Single Dose Oral Administration to Cynomolgus Monkeys

[0393] Single-dose oral administration of MRM-3379 to male and female cynomolgus monkeys was carried out in a single-dose PK study to evaluate single-dose toxicokinetic (TK) parameters during repeated dose toxicology studies. A single-dose p.o. pharmacokinetic study was performed with the administration of 3, 6, or 10 mg / kg to male cynomolgus monkeys, resulting in emesis that occurred from 1 to 8 hours post-dose. Apparent tachyphylaxis to the emetic response seen at dose levels > 3 mg / kg was achieved using a lead-in phase of a once- daily p.o. administration of 1 mg / kg / day for 5 days. As a result of incorporating this lead-in phase, MRM-3379 was administered up to 200 mg / kg without dose-limiting emesis.73321886535vlAttorney Docket No: 254409.000968 PATENT

[0394] MRM-3379 was slowly absorbed after p.o. administration to the monkey; Tmaxwas attained from about 2.00 to 6.00 hours. In the dose-linear range (0.3 to 10 mg / kg), the decline in MRM-3379 plasma concentrations began shortly following Tmaxshowing mean apparent T1 / 2 of 4.59 to 7.79 hours. At higher oral dose levels (60 and 200 mg / kg), elevated MRM-3379 plasma concentrations close to Cmax were sustained up to at least 24 hours postdose, suggesting saturation of clearance.

[0395] Across single oral dose levels of 0.3 to 200 mg / kg, exposure (Cmaxand AUCo-t) to MRM-3379 was linear up to 10 mg / kg, after which exposure increased in a less than doseproportional manner. Absorption after a single dose reached a plateau of about 60 mg / kg. The mean absolute oral bioavailability of MRM-3379 (0.3 mg / kg p.o. and intravenous (i.v.) dose) in the monkeys was 22.8%.

[0396] The monkey was deemed to be the more sensitive animal species to MRM-3379 toxicity with a NOAEL of 10 mg / kg / day after 13 weeks of p.o. dosing resulting in mean steady-state Cmax and AUCo-t values of 374 ng / mL and 3910 ng«h / mL, respectively, in males and 280 ng / mL and 2350 ng*h / mL, respectively, in females. Safety margins of 66.7 (Cmax) to 193 (AUCo-t) are attained when the MRM-3379 exposures (Cmax = 4.20 ng / mL and AUCo-t = 12.2 ng*h / mL) observed at 2.5 mg human dose are compared to lowest of those obtained in the monkey at 10 mg / kg / day (the NOAEL).Example 6. Clinical Study 1 in Healthy Non-Elderly and Elderly Human Adults

[0397] The first clinical study in healthy adults was based on Single Ascending Dose (SAD), double-blind, placebo-controlled protocols in healthy males and females (non-childbearing potential), non-elderly adults (18 to 59 years of age), and elderly (60 to 80 years of age) subjects. The safety, tolerability, PK, and PD effects of single doses of MRM-3379 or placebo were evaluated.

[0398] The safety data from both the non-elderly cohorts (1 mg, 3 mg, 5 mg, and 7.5 mg) and the elderly cohorts (3 mg and 5 mg) indicated that MRM-3379 at these single dose levels was generally well-tolerated. The 15 mg dose level in non-elderly adult subjects produced74321886535vlAttorney Docket No: 254409.000968 PATENT vomiting in 4 out of 5 subjects dosed with MRM-3379 and was deemed not well-tolerated. Dose escalation above 15 mg was not conducted for this reason. There were no serious adverse events (SAEs), nor were there any adverse events (AEs) requiring premature withdrawal from the study. All AEs were rated to be mild or moderate in severity by the Investigator, and all resolved relatively quickly in most instances without requiring any action to be taken. None of the protocol-stipulated dose escalation stopping criteria were met, and all physical examination, neurologic examination, ECG findings, vital signs measurements, and laboratory findings were either normal or, if abnormal, were deemed to be not clinically significant by the Investigators. Adverse events that occurred in at least two (2) healthy non- elderly adult subjects who received MRM-3379 included nausea (7 subjects), vomiting (7 subjects), dizziness (2 subjects), orthostatic intolerance (2 subjects), and hyperhidrosis (2 subjects). No AEs occurred in more than two (2) healthy elderly subjects who received MRM- 3379.

[0399] The single-dose PK data indicated that MRM-3379 was readily absorbed from the gastrointestinal tract in healthy nonelderly adults, with mean exposures (peak and overall) generally consistent with predictions based on nonclinical data. Maximum plasma concentrations generally occurred 1 to 3 hours postdose (mean Tmax = 2.11 hours). Both peak (Cmax) and overall (AUC) exposures generally increased proportionally with increases in dose level (Figure 9 and Table IF). Figure 9 shows a linear plot of arithmetic mean MRM-3379 plasma concentrations versus nominal time postdose by study part and treatment (primary pharmacokinetic population). Mean terminal elimination half-life (T1 / 2) varied depending on the dose level cohort but was generally between 4.49 and 9.89 hours.Table IF. Summary of the Pharmacokinetic Parameters for MRM-3379 Following Single Oral Doses of MRM-3379 in the Fasted State in Healthy Non-Elderly Adult Subjects75321886535vlAttorney Docket No: 254409.000968 PATENTN = Number of subjects in PK population; Cmax = Maximum observed plasma concentration; Tmax= Time to reach Cmax; AUCo-t= Area under the concentration-time curve (AUC) from time zero (0) to a definite time;AUCo-o = AUC from time zero (0) to infinity; U = Terminal rate constant; T1 / 2 = Halflife; CL / F = Apparent total clearance of the drug from plasma after oral administration; Vz / F = Apparent volume of distribution after oral administration; PK = Pharmacokinetic; CV = Coefficient of variation.Geometric Mean (gCV%) data are presented.Part A Cohort 2 (3 mg) randomized 10 subjects (7 active, 3 placebo) first dosed under fasted conditions (Cohort 2a) and then dosed under fed (high-fat / high-calorie meal) conditions (Cohort 2b). a Data from 2 subjects only as the PK data from other 3 subjects in the cohort were excluded from the primary analysis due to vomiting. b Median (minimum-maximum).

[0400] In the food effect cohort (Cohort 2), two single 3 mg doses were administered 7 days apart in a crossover fashion (once under fasting conditions and once under fed conditions with a high-fat / high-calorie breakfast). Two subjects did not return for dosing of MRM-3379 under the fed condition. As shown in Figure 10 and Table 2, the analysis demonstrates an effect of food following administration of 3 mg MRM-3379, reflected by a decrease in mean 76321886535vlAttorney Docket No: 254409.000968 PATENTCmax, while AUC parameters were largely unaffected in the presence of the high-fat / high- calorie meal. Administration of MRM-3379 with food decreased peak plasma concentrations; the geometric mean ratio (GMR; 90% confidence interval [CI]) for Cmax was 0.28 (0.15 - 0.52). The median Tmax was markedly delayed with food (8.97 hours in the fed state versus 1.74 hours in the fasted condition), indicating slowed oral absorption of MRM-3379. The overall exposure was comparable with food, and the GMR (90% CI) for AUCo-tand AUCo-oo were 1.06 (0.61 - 1.86) and 1.05 (0.6 - 1.82), respectively.Table 2. Summary of Pharmacokinetics of MRM-3379 Following Single Oral Doses of 3 mg MRM-3379 in the Fed and Fasted States- = Not calculated; PK = Pharmacokinetic; GMR = geometric mean ratio; CV = Coefficient of variation.Natural log-transformed PK parameter fit by a model with treatment fixed and subject random. Model least squares means and mean difference back-transformed to evaluate the geometric means and GMR with a 90% CI (two-sided) for the fed to fasted comparison. Geometric Mean (gCV%) data are presented.

[0401] In healthy, non-elderly subjects, the effect of food on PK and gastrointestinal (GI) tolerability was also evaluated in a separate cohort of subjects receiving 7.5 mg MRM-3379. As shown in Table 3, a light meal produced a slight decrease (approximately 20%) in mean Cmax and an increase in Tmax without impacting overall AUC exposures. Although the sample size was small, the incidence of vomiting appeared to be reduced in the presence of food.77321886535vlAttorney Docket No: 254409.000968 PATENTTable 3. Summary of Pharmacokinetics and Gastrointestinal Tolerability of MRM-3379 Following Single Oral Doses of 7.5 mg MRM-3379 in the Fed and Fasted StatesCL / F = Apparent total clearance of the drug from plasma after oral administration; Vz / F = Apparent volume of distribution after oral administration;PK = Pharmacokinetic: CV = Coefficient of variation.Geometric Mean (gCV%) data are presented. a Median (minimum-maximum).

[0402] In healthy elderly subjects, single doses of 3 mg and 5 mg MRM-3379 were rapidly absorbed from the gastrointestinal tract following oral administration (Figure 11 and Table 4). C max plasma concentrations and AUC exposures were generally proportional between the two dose levels.Table 4. Summary of the Pharmacokinetic Parameters for MRM-3379 Following Single Oral Doses of MRM-3379 in Healthy Elderly Subjects321886535vlAttorney Docket No: 254409.000968 PATENTCL / F = Apparent total clearance of the drug from plasma after oral administration; Vz / F = Apparent volume of distribution after oral administration; PK = Pharmacokinetic; CV = Coefficient of variation.Geometric Mean (gCV%) data are presented.Part A Cohort 2 (3 mg) randomized 10 subjects (7 active, 3 placebo) first dosed under fasted conditions.(Cohort 2a) and then dosed under fed (high-fat / high-calorie meal) conditions (Cohort 2b). a Median (minimum-maximum).

[0403] Table 5 compares the PK parameters for the 3 mg and 5 mg dose levels between non-elderly adult and elderly subjects, hr general, the PK parameters were consistent between these two groups for the two dose levels tested, although the AUC values trended higher in the 5 mg elderly cohort compared to the 5 mg adult group (and the variability was higher for the 5 mg elderly cohort).Table 5. Summary Pharmacokinetic Parameters of MRM-3379 Following OralAdministration of 3 mg and 5 mg in Non-Elderly Adult and Elderly Healthy Subjects79321886535vlAttorney Docket No: 254409.000968 PATENTValues represent the mean (or median in the case of Tmax) of 6 subjects per dose level. %CVs are provided in parentheses (or range for Tmax).Example 7. Clinical Study 2 in Healthy Non-Elderly and Elderly Human Adults

[0404] The second clinical study in healthy adults was based on Multiple Ascending Dose (MAD), double-blind, placebo-controlled protocols in healthy males and females (nonchild-bearing potential), non-elderly adults (18 to 59 years of age), and elderly (60 to 80 years of age) subjects. The safety, tolerability, PK, and PD effects of 21 consecutive daily doses of MRM-3379 or placebo were evaluated. The dose levels for healthy, non-elderly adult subjects were 1 mg / day, 2.5 mg / day, and 5 mg / day and the dose levels for the healthy elderly subjects were 2.5 mg / day and 5 mg / day. Assessments of safety and tolerability included AEs, vital signs (i.e., blood pressure, heart rate, and temperature), urinalysis, hematology, serum chemistry, ECGs, GI safety markers, and physical examinations. In addition, PK and PD measurements (e.g., plasma cAMP, memory / cognition tests) were performed. The study also included an open-label, 2-period, fixed-sequence drug interaction study arm to evaluate the safety, tolerability, and effects of multiple doses of MRM-3379 (5 mg / day) on the PK and PD of warfarin in healthy adult and elderly subjects. Lastly, Study MRM-3379-102 also included a cohort undergoing continuous sampling of CSF for measurement of MRM-3379 and cAMP concentrations.

[0405] Preliminary, blinded, safety-related findings from Study MRM-3379-102 based on adverse event incidence and vital signs, 12-lead ECG, and clinical laboratory parameter changes were unremarkable, indicating that all dose levels administered were generally well- tolerated (1 mg / day, 2.5 mg / day, and 5 mg / day in non-elderly adult subjects; 2.5 mg / day and 5 mg / day in elderly subjects). No SAEs were reported in this study. None of the protocol-80321886535vlAttorney Docket No: 254409.000968 PATENT stipulated dose-escalation-stopping criteria were met during the study. One subject withdrew consent from the study after one (1) day of dosing with 5 mg / day MRM-3379 in the warfarin- MRM-3379 cohort after experiencing an AE of abdominal discomfort. One subject in the CSF cohort withdrew consent due to a family emergency after receiving one dose of MRM-3379 or placebo on Day 1. The multiple p.o. dose PK data from Study MRM-3379-102 in healthy non- elderly adult subjects indicate that MRM-3379 achieved maximum plasma concentrations Tmax at 1 to 3 hours postdose (Figure 12 and Table 6). Both peak (Cmax) and overall (AUG) exposures were generally dose-proportional, and Day 1 PK profiles of 1 mg and 5 mg were generally consistent with the single-dose plasma concentrations at these doses. Little, if any, drug accumulation occurred during the process of reaching steady-state plasma levels, as the accumulation ratios (AR) for Cmax and AUC ranged from 0.90 to 1.81 on Day 10 and 21 (versus Day 1) for each cohort. Apparent T1 / 2 values after 21 days of dosing ranged from 6.26 to 9.94 hours, depending on the dose level cohort. Steady-state plasma concentrations appeared to be achieved by 7 days of daily dosing (Table 7).Table 6. Pharmacokinetic Parameters for MRM-3379 After 1, 10, and 21 Days of Daily Oral Doses of MRM-3379 in Healthy Non-Elderly Adult Subjects321886535vlAttorney Docket No: 254409.000968 PATENTAUCo-24= Area under the concentration-time curve (AUC) from time zero (0) to 24 hours postdose; ARCmax,dl0 = Accumulation ration for Cmax, day 10; ARAUC,dl0 = Accumulation ration for AUC, day 10; d21 = Day 21; %CVs = Percent coefficient of variation.All dose levels were p.o. administered daily for 21 days in the fasted state. Values represent the mean (or median in the case of Tmax) of 9 subjects per dose level. %CVs are provided in parentheses (or range for Tmax).Table 7. Mean Plasma Trough Concentrations (pg / mL) 24 Hours After Daily OralDosing with MRM-3379 in Healthy Non-Elderly Adult Subjects%CVs = Percent coefficient of variation.Means were calculated based on the number of subjects with detectable plasma concentrations of MRM-3379.% CVs are provided in parentheses.Two subjects had measurable plasma concentrations (7 subjects had values that were below the limit of quantitation, i.e., 40 pg / mL). b Six subjects had measurable plasma concentrations of MRM-3379 (3 subjects had values that were below the limit of quantitation).

[0406] The multiple oral dose PK data in healthy elderly subjects generally paralleled the PK data observed in healthy non-elderly adult subjects at similar doses (Table 8). MRM-3379 showed generally dose-proportional exposures between the 2.5 mg / day and 5 mg / day dose levels of MRM-3379. There were no consistent differences in mean Cmax or mean AUC values between healthy adult and healthy elderly subjects receiving the same dose levels of MRM- 3379 (i.e., 2.5 mg / day and 5 mg / day). The mean T1 / 2, which generally trended higher in82321886535vlAttorney Docket No: 254409.000968 PATENT healthy elderly subjects compared to healthy adults, was 13.4 and 15.1 hours after 21 days of dosing of 2.5 mg / day and 5 mg / day MRM-3379, respectively. Mean T1 / 2 values were generally higher on Day 21 compared to Day 1 and 10, which likely reflects the shorter sampling times (24 hours) on Day 1 and 10 compared to Day 21 (120 hours). Minimal accumulation occurred with repeated daily dosing in healthy elderly subjects as accumulation ratios for Cmax and AUC ranged from 0.89 to 1.21. Steady-state plasma concentrations appeared to be achieved within 7 days of dosing (Table 9).Table 8. Pharmacokinetic Parameters for MRM-3379 After 1, 10, and 21 Days ofDaily Oral Doses of MRM-3379 in Healthy Elderly SubjectsAUCo-24 = Area under the concentration-time curve (AUC) from time zero (0) to 24 hours postdose; ARCmax,dlO = Accumulation ration for Cmax, day 10; ARAUC,dl0 = Accumulation ration for AUC, day 10; d21 = Day 21; %CVs = Percent coefficient of variation.All dose levels were orally administered daily for 21 days in the fasted state. Values represent the mean (or median in the case of Tmax) of 9 subjects per dose level. % CVs are provided in parentheses (or range for Tmax).Table 9. Mean Plasma Trough Concentrations (pg / mL) 24 Hours After Daily OralDosing with MRM-3379 in Healthy Elderly Subjects in Study MRM-3379-10283321886535vlAttorney Docket No: 254409.000968 PATENT%CVs = Percent coefficient of variation.Means were calculated based on the number of subjects with detectable plasma concentrations of MRM-3379.% CVs are provided in parentheses.Eight subjects had measurable plasma concentrations (1 subject had values that were below the limit of quantitation, i.e., 40 pg / mL).

[0407] Table 10 shows a side-by-side comparison of the PK parameters between non- elderly adult and elderly subjects receiving the same dose levels of MRM-3379. The PK parameters appeared to be similar between non-elderly adults and elderly subjects, although the TI / 2 tended to be higher in elderly subjects compared to non-elderly adults.Table 10. Summary Pharmacokinetic Parameters of MRM-3379 Following21 Days of Oral Administration of 2.5 mg and 5 mg in Non-Elderly Adult and Elderly Healthy Subjects84321886535vlAttorney Docket No: 254409.000968 PATENTAll dose levels were orally administered daily for 21 days in the fasted state. Values represent the mean (or median in the case of Tmax) of 9 subjects per dose level. %CVs are provided in parentheses (or range for Tmax).

[0408] A cohort of healthy non-elderly adults underwent continuous Cerebrospinal Fluid Sampling (CSF) sampling for evaluation of brain penetration and central PD effects of MRM-3379. The results indicate that MRM-3379 is present in CSF after multiple daily dosing with 5 mg / day MRM-3379 (Figure 13). The peak concentrations in CSF occurred at 2 hours postdose, which is similar to the plasma Tmax of MRM-3379. These findings demonstrate that MRM-3379 can readily partition into the CSF after p.o. administration, and are consistent with brain penetration of MRM-3379.Example 8. Clinical Study 3 in Healthy Non-Elderly Adult and Elderly Sub jects

[0409] This was a single- and repeat-dose (7 to 10 days), open-label, non-randomized PET study to evaluate the dose-dependency of PDE4 occupancy in the brain resulting from p.o. administration of MRM-3379. The subjects were healthy, non-elderly, and elderly adults. More specifically, the study used Positron Emission Tomography (PET) imaging to characterize the inhibition of [nC]-R-rolipram binding to brain PDE4 by MRM-3379. Plasma concentrations of MRM-3379 were also examined to evaluate the PK of MRM-3379 in this study and to relate plasma concentrations of MRM-3379 to brain PDE4 occupancy. Dose levels examined included single doses of 3 mg, 7.5 mg, and 15 mg MRM-3379, while a multiple dose level cohort of 5 mg / day was also evaluated. The clinical conduct of the study is complete, although the final CSR is pending.

[0410] MRM-3379 was generally well-tolerated in this study. All subjects were prophylactically administered the antiemetic medication granisetron to prevent nausea and vomiting from occurring while in the PET scanner. The safety data (clinical safety labs, vital signs, ECGs) indicate that single doses of up to 15 mg and multiple doses of 5 mg / day were generally well-tolerated. There were no SAEs, nor were there any AEs85321886535vlAttorney Docket No: 254409.000968 PATENT requiring premature withdrawal from the study. Adverse events reported in more than one subject included nausea (3 subjects) and injection site wrist pain (2 subjects).

[0411] Target site engagement (i.e., occupancy) of MRM-3379 at brain PDE-4 sites was evaluated using the selective PDE-4 PET tracer [11CJ-R-rolipram. MRM-3379 produced low but measurable PDE-4 brain occupancy at single doses of 7.5 mg and 15 mg and at multiple doses of 5 mg / day in healthy subjects. Table 11 provides the mean occupancy values averaged across 14 different brain regions of interest, as well as Umax and AUC plasma concentrations of MRM-3379 for each dose level cohort.Table 11. Brain PDE-4 Occupancy of MRM-3379 After Single and Multiple Dose Administration in Healthy Non-Elderly Adult and Elderly SubjectsN = Number of subjects; ND = Not detected; Cmax = Maximum observed plasma concentration; AUC 1-2.5 = Area under the concentration-time curve (AUC) from time one (1) to 2.5 hours postdose; SD = Standard deviation. Values represent the mean (SD) of 3 subjects.AUC1-2.5 h is the plasma AUC determined from 1 to 2.5 h after MRM-3379 dosing, the time of the PET scan.

[0412] Figure 14 provides the % PDE4 occupancy values versus the plasma Cmax andAUC values of MRM-3379 for individual subjects. In general, there was a linear relationship between % occupancy (target site engagement) and MRM-3379 plasma concentrations. These results are consistent with the MAD study in which MRM-337986321886535vlAttorney Docket No: 254409.000968 PATENT was present in the CSF after multiple doses with 5 mg / day MRM-3379, which further confirmed the brain penetration of MRM-3379. Based on Study MRM-3379-103, dose levels of 3 mg and below are not expected to produce measurable brain PDE4 occupancy, although those dose levels are expected to access the brain (based on the CSF data). Doses of 0.5 mg and 2.5 mg are in the predicted therapeutic range as they approximate plasma exposures of MRM-3379 that were associated with efficacy in nonclinical models (measurable PDE4 occupancy was not apparent in rodents at efficacious exposures).

[0413] Examples 6-8 showed that single doses (up to 7.5 mg) in non-elderly and (up to 5 mg) in the elderly were generally well tolerated with most AEs of mild intensity and transient. 15 mg was considered not well tolerated. Multiple doses (up to 5 mg) are generally well tolerated, with most AEs of mild intensity and transient. There were no observed effects on QTc interval dose-proportional exposures up to 15 mg / day. Food decreased DS exposures, resulting in a corresponding decrease in AEs. At the dosage range anticipated to be therapeutic (1-5 mg / day), MRM-3379 was not associated with significant GI side effects.Example 9. Evaluation of MRM-3379 in FXS-Knockout Mice Based on a Mouse Model of FXS

[0414] A second-generation FMRI knock out (FMRI KO2) mouse model was developed. The chronic effect of MRM-3379 on ameliorating the FXS phenotype in multiple behavioral assays in the FMRI KO2 mouse model of FXS was studied.MethodsDosing Regime

[0415] In each experiment, mice were treated daily for 14 days by oral gavage with either vehicle or MRM-3379. Mouse groups were wild-type C57B16 mice exposed to vehicle (WT Vehicle), FMRI KO2 mice exposed to vehicle, and FMRI KO2 mice exposed to MRM-3379 at different concentrations. Two trials were conducted. The study matrices for Trial 1 and Trial 2 are listed in Table 12 and Table 12A respectively87321886535vlAttorney Docket No: 254409.000968 PATENT

[0416] After two weeks of treatment, the mice were profiled for open field activity (locomotor activity), social interaction (social novelty), and natural behaviors (nesting and marble burying behaviors). Each treatment group included 10 adult male mice.Table 12. Study Matrix Table for Trial 1Table 12A. Study Matrix Table for Trial 2

[0417] The administration volume was 0.1 mL / 10 g of body weight. MRM-3379 was dosed PO in 1% (w / v) carboxymethylcellulose, medium viscosity in water, prepared weekly, and stored at 2-8°C. Concentrations did not exceed 2 mg / mL. For dosing, the mixture was warmed to room temperature and stirred continuously.88321886535vlAttorney Docket No: 254409.000968 PATENTAnimal Husbandry

[0418] Mice were housed in groups of the same genotype in a temperature and humidity-controlled room with a 12-h light-dark cycle (lights on 7 am to 7 pm). Food and water were available ad libitum. Mice (Postnatal day 70 upon start of administration) were group housed (5 per cage) in an SPF facility and maintained until initiation of treatment at 3 months of age. During this time, mice were acclimated to experimenters and procedures were studied to minimize stress during treatment and testing.

[0419] Mice were weighed prior to the start of each administration throughout the study period, and at euthanasia. At the conclusion of all behavioral tests, mice were humanely euthanized, and blood and brain tissue samples were collected.

[0420] The procedures are in line with the requirements of the UK Animals (Scientific Procedures) Act, 1986.Behavioral Tests

[0421] Behavioral screening of the mice (n=10 per group) was conducted in the following order with 3 days between each test:1) Hyperactivity: Open field2) Sociability: Three chamber partition test4) Activity of daily living (hippocampal-dependent): nesting5) Activity of daily living (hippocampal-dependent): marble burying

[0422] Prior to each test, a mouse that was not included in the study was placed in the experimental apparatus for 3 min. Then, this non-study animal was removed, and the apparatus was cleaned with moist and dry tissues before placing a study mouse into the apparatus. The aim was to create a low but constant background mouse odor for all experimental subjects.

[0423] Experimenters were blinded to mouse genotype and treatment throughout all behavioral tests and data analysis. Euthanasia and full brain samples were extracted and kept at -80°C.89321886535vlAttorney Docket No: 254409.000968 PATENTFXS Mouse Model

[0424] The FXS mouse model, a second-generation FMRI knock out (FMRI KO2) mouse model and their corresponding wildtype (WT) littermates were developed. FMRI KO2 mice were provided by FRAXA Research Foundation, MA, USA. FMRI KO2 mice were generated by deleting the promoter and first exon of the FMRI gene according to Mientjes et al. 2006, Neurobiol. Dis. 21, 549-555, and then were backcrossed to a C57BE / 6J background for more than eight generations. The FMRI K02 mice are FMRP protein and mRNA null, and recapitulate FXS-related behavioral abnormalities, including age-dependent presentation, such as hyperactivity, repetitive behavior, and deficits in learning and memory. The FMRI K02 mice were used in the studies in this Example.Animal Housing

[0425] The FMRI KO2 mice were housed in four per cage groups of the same genotype in a temperature- and humidity-controlled room with a 12-h light-dark cycle (lights on 7 a.m.-7 p.m.). Mice were housed in commercial plastic cages (40 x 23 x 12 cm) with Aspen bedding and without environmental enrichment on a ventilated rack system. Food and water were available ad libitum, except during test sessions. Testing was conducted during the light phase on male FMRI KO2 mice and their WT littermates.Open-Field Hyperactivity

[0426] An open-field apparatus was used to test hyperactivity and habituation to a novel environment, in which decreased exploration as a function of repeated exposure to the same environment may be an index of memory. The Dutch-Belgian Fragile X Consortium. Bakker C. E., Verheij C., Willemsen R., van der Helm R., Oerlemans F., et al. (1994). FMRI knockout mice: a model to study fragile X messenger ribonucleoprotein. Cell 18, 23-33. Each mouse was exposed individually to the open field. The distance travelled in one session corresponding to 30 minutes was measured 30 minutes after treatment administration. The open-field assay was performed using an automated system including a Noldus activity monitor chamber with the associated90321886535vlAttorney Docket No: 254409.000968 PATENTEthoVision software (Noldus Information Technology Inc.. Leesburg, VA, USA). A mouse was placed into a comer square facing the wall, and horizontal locomotor activity, measured as distance travelled in centimeters (cm) by the number of squares entered with the whole body, was recorded for 30 min. Self-grooming was evaluated as the time spent grooming was recorded for 3 min in the open field.Activities of Daily Living (ADL)

[0427] Activities of daily living (ADL) are defined as normal activities such as meal preparation, bathing, dressing, and other practical self-care skills. The hippocampus has been proposed to be vital for the performance of ADL of mice. Rodents with lesions of the hippocampus typically perform very poorly on ADL. Several tests of ADL in mice have been developed: nesting, marble burying, hoarding, and burrowing.Nesting

[0428] Nesting behavior is a normal behavior of mice, and mice are highly motivated to build nests. The nest has several functions, including increasing litter survival, regulation of body temperature, protection from predators or aggressive cage mates, shelter from cold or draft, and in laboratory conditions is a form of environmental enrichment. For small rodents, nests are important in heat conservation as well as reproduction and shelter. Nesting was measured in the home cages of mice. The mice first shred the tightly packed material, then arranged it into a nest. The protocol used pressed cotton squares and a definitive 5-point nest-rating scale. The test was done overnight. Scores of the quality of the resulting nest were assessed on a 5-point scale. How the nesting was scored is described below:Nesting scoring1 The nestlet is largely untouched (> 90% intact).2 The nestlet is partially tom up (50-90% remaining intact).91321886535vlAttorney Docket No: 254409.000968 PATENT3 The nestlet is mostly shredded but often there is no identifiable nest site: < 50% of the nestlet remains intact but < 90% is within a quarter of the cage floor area, i.e., the cotton is not gathered into a nest but spread around the cage.4 An identifiable, but flat nest: > 90% of the nestlet is tom up, the material is gathered into a nest within a quarter of the cage floor area, but the nest is flat, with walls higher than mouse body height (curled up on its side) on less than 50% of its circumference.5 A (near) perfect nest: > 90% of the nestlet is torn up, the nest is a crater, with walls higher than mouse body height on more than 50% of its circumference.Marble Burying

[0429] Mice exhibit various species-typical behaviors such as digging and burrowing. They dig in the ground to find food, to hoard food, to create a refuge from predators or cold and to make a safe nursery area for the young. In the laboratory, mice dig vigorously in deep bedding such as wood chips. This behavior is sensitive to strain differences and drugs. Digging can be quantified by manual timing. Alternatively, the bedding can be covered with glass marbles and the number buried can be counted after a set time.

[0430] Transparent plastic cages were filled with a 10-cm deep layer of sawdust on top of which 10 glass marbles were placed in two rows. Each animal was left undisturbed in such a cage for 30 min, after which the number of marbles that were buried to at least two-thirds of their depth was recorded.Social Interaction

[0431] The partition test is a measure of social recognition (SR) that works on the same principle as novel object recognition (NOR), except in this instance the test animals need to differentiate between a novel and a familiar mouse. A mouse was placed in a cage with one familiar mouse (F) and one new mouse (N). The amount of time spent with each mouse over 10 minutes was measured.92321886535vlAttorney Docket No: 254409.000968 PATENT

[0432] The apparatus was a test arena / cage within the same order of magnitude of size as the adult’s home cage. Typically, this is a 40 x 23 x 12 cm cage, with a Perspex lid to facilitate viewing the mice. It should have fresh wood chipping on the floor. Preferably also give it a background mouse odor by putting in some non-experimental mice before starting to test. Mice were transferred to experimental room 10-15 min prior to test to wake them up. Simultaneously, both a test subject and a juvenile were placed in the test cage. The total duration and number of bouts of social investigation, defined as sniffing and close following (\2 cm from the tail) of the stimulus juvenile, were measured for 3 min.Statistical analysisData were analyzed by one-way analysis of variance (ANOVA) followed by pairwise post-hoc comparisons where appropriate using Tukey’s Multiple Comparison Test. Data are represented as the mean and standard error of the mean (SEM).ResultsOpen Field Test

[0433] Vehicle-treated FMRI KO2 mice display a hyperactive phenotype by traveling a significantly greater distance in the open field compared to WT mice. Chronic treatment with MRM-3379 (at 0.03 mg / kg, 0.1 mg / kg, 0.3 mg / kg, and 1.0 mg / kg) significantly reversed this phenotype (Figures 15A and 15B for Trials 1 and 2 respectively). The statistical analysis identified significantly increased horizontal locomotor activity in vehicle-treated FMRI KO2 mice in the open field than wild- type littermate mice (p <0.0001). FMRI KO2 mice travelled a greater distance compared to WT mice. FMRI KO2 mice treated with MRM-3379 (at 0.03 mg / kg, 0.1 mg / kg, 0.3 mg / kg, and 1.0 mg / kg) showed significantly reduced open field activity (i.e., travelled less distance) in comparison to vehicle-treated FMRI KO2 mice (p< 0.0001) and were not significantly different from control mice. Bars indicate mean values (mean ± SEM). Points correspond to values from individual mice. Asterisks represent significant change;93321886535vlAttorney Docket No: 254409.000968 PATENT ns. not significant; ****P < 0.0001; n = 10: *P < 0.02. After treating with MRM-3379. the distance travelled by FMRI KO2 mice was not different from WT mice.Activities of Daily Living (ADL)

[0434] Nesting: Vehicle-treated FMRI KO2 mice scored between 1 and 2 in nesting, indicating that this hippocampus-dependent activity of daily living was compromised in this animal model. Chronic treatment using MRM-3379 (at 0.03 mg / kg, 0.1 mg / kg, 0.3 mg / kg, and 1.0 mg / kg) reversed the nesting quality score of FMRI KO2 mice back to the level of the WT littermates (Figures 15C and 15D for Trials 1 and 2 respectively). During the test, vehicle-treated FMRI KO2 mice were not able to build a nest, while the WT animals treated with the vehicle built a perfect or nearly perfect nest. Chronic treatment with MRM-3379 (at 0.03 mg / kg, 0.1 mg / kg, 0.3 mg / kg, and 1.0 mg / kg) significantly improved nest building of the FMRI K.O2 mice. FMRI KO2 mice treated with MRM-3379 (at 0.03 mg / kg, 0.1 mg / kg, 0.3 mg / kg, and 1.0 mg / kg) had higher nest quality scores compared with those treated with vehicle. Bars indicate mean values (mean ± SEM). Points correspond to values from individual mice. Asterisks represent significant change; ns, not significant; ****P < 0.0001; n = 10. After treating with MRM-3379, the nest quality scores for FMRI KO2 mice were not different from WT mice.

[0435] Marble Burying: The graphs in Figures 15E and 15F plot the number of marbles buried in the different groups in Trial 1 and Trial 2 respectively. FMRI KO2 mice buried significantly less marbles than WT mice. Chronic treatment with MRM-3379 (at 0.03 mg / kg, 0.1 mg / kg, 0.3 mg / kg, and 1.0 mg / kg) significantly improved the phenotype of the FMRI KO2 mice. Bars indicate mean values (mean ± SEM). Points correspond to values from individual mice. Asterisks represent significant change; ns, not significant; ****P < 0.0001; n = 10. FMRI KO2 mice treated with MRM-3379 (at 0.03 mg / kg, 0.1 mg / kg, 0.3 mg / kg, and 1.0 mg / kg) buried more marbles compared with those treated with vehicle. After treating with MRM-3379, the number of marbles buried by FMRI KO2 mice were not different from WT mice.94321886535vlAttorney Docket No: 254409.000968 PATENT

[0436] Social Interaction: Three chamber partition tests were performed. Results are presented as time spent with the novel (N) or familiar (F) mouse (Figures 15G and 15H for Trials 1 and 2 respectively). WT mice spent more time with a new mouse than with a familiar mouse. During the social interaction testing FMRI KO2 mice showed no preference for the novel mouse. FMRI KO2 chronically treated with MRM-3379 (at 0.03 mg / kg, 0.1 mg / kg, 0.3 mg / kg, and 1.0 mg / kg) significantly reversed this phenotype. The FMRI KO2 mice treated with the vehicle showed no preference for either the novel or the familiar mouse, as demonstrated by their low scores, indicating that social memory was compromised in this animal model. Treatment with MRM-3379 (at 0.03 mg / kg, 0.1 mg / kg, 0.3 mg / kg, and 1.0 mg / kg) was able to reverse the social memory (SM) deficit in FMRI KO2 mice back to the level observed for the WT group, indicating improvement in social memory formation. FMRI K.O2 mice treated with MRM-3379 (at 0.03 mg / kg, 0.1 mg / kg, 0.3 mg / kg, and 1.0 mg / kg) spent more time with a new mouse than a familiar mouse.Summary

[0437] Across all behavioral tests MRM-3379 fully reversed the behavioral phenotype of the FMRI KO2 mice (p-value for all comparisons <0.0001). Based on the above FXS mouse model results, MRM-3379 showed promising preclinical efficacy in rescuing multiple behavioral phenotypes associated with FXS in the FMRI knockout mouse model. When administered at 0.03 mg / kg, 0.1 mg / kg, 0.3 mg / kg, and 1.0 mg / kg, MRM-3379 demonstrated dose-dependent improvements in a battery of behavioral assays that reflect core FXS -related deficits.

[0438] At these concentrations, MRM-3379 reversed the hyperactivity phenotype typically observed in FMRI KO2 mice during the open field test, normalizing locomotor activity levels to those of wild-type controls. In the marble burying test, a hippocampal- dependent activity of daily living and also a paradigm reflective of repetitive and anxiety-95321886535vlAttorney Docket No: 254409.000968 PATENT related behaviors, treatment with MRM-3379 restored burying behavior toward wild-type performance, indicating a potential cognitive and normalization of stereotyped behaviors.

[0439] Furthermore, nest building, also a hippocampal-dependent activity of daily living behavior impaired in FMRI KO2 mice and indicative of motivational deficits, was significantly improved following treatment. The social memory deficit — assessed through social novelty preference and recognition tasks — was also ameliorated, suggesting a restorative effect on hippocampal and prefrontal cortex -dependent circuitry disrupted in FXS.

[0440] Taken together, these findings suggest that MRM-3379 improved multiple behavioral domains relevant to the fragile X phenotype in a mouse model, likely through modulation of intracellular signaling pathways involved in synaptic plasticity and cognitive processing. The consistent efficacy across various dosing regimens supports its potential as a therapeutic candidate for FXS and warrants further investigation, including exploration of long-term effects, neuronal spine maturity, washout effect, and translational biomarkers. The consistent effect of MRM-3379 across doses and behavioral assays supports its potential as a therapeutic candidate for the treatment of FXS.Example 10. Phase 2 and Phase 3 Studies

[0441] A Phase 2 study of male participants with a full FXS mutation will be conducted. The Phase 2, randomized, placebo-controlled study will investigate the effects of MRM-3379 on safety and tolerability, and on cognitive and functional assessment measures. Males aged 13-45 years of age (N ~60) will be given one of three dose levels of MRM-3379 (0.5 mg BID, 2 mg QD, or 2 mg BID) or placebo for 12 weeks. The primary objective of the study will be to evaluate the safety and tolerability of MRM- 3379 with secondary objectives to evaluate the efficacy of MRM-3379 on the change from baseline on the NIH-TB Crystallized Cognition score and a variety of secondary endpoints. These measures will be conducted at Baseline and Weeks 6 and 12. If96321886535vlAttorney Docket No: 254409.000968 PATENT appropriate safety, tolerability, and efficacy are observed in the Phase 2 study, a Phase 3 study that may include adult, adolescent, and pediatric, and repeat or methylation mosaic participants either as part of a main cohort or separate cohorts will be conducted.Example 11. Capsule Formulations of MRM-3379

[0442] A capsule formulation (Table 12A) was used in the clinical studies described above.Table 12A. Compositions of MRM-3379 Capsules

[0443] The dry blending manufacturing process for the fill formulations is outlined below. The total batch size of each formulation was about 300-500 capsules.1. Blend diluent, disintegrant, and glidant for not less than (NLT) 5 minutes in a 16 oz Nalgene® HDPE bottle.2. Discharge about 80% of the blend, leaving about 20% of the blend in the bottle.3. Add MRM-3379 drug substance to the bottle, followed by 20% of the discharged blend. Blend for NLT 5 min.4. Add one-half of the remaining discharged blend to the bottle and blend for NLT 5 min.5. Add the remaining discharged blend to the bottle and blend for NLT 5 min.97321886535vlAttorney Docket No: 254409.000968 PATENT6. Screen the blend through a 40-mesh screen.7. Transfer the screened material back to the bottle and blend for NLT 10 min.8. Add pre-screened lubricant to the bottle and blend for 2-3 min.9. Perform blend uniformity (BU) testing from 3-5 locations.10. If BU is not achieved, blend for another 2-3 min and perform BU testing.11. If BU is achieved, encapsulate the blend into capsules using a Profill™ encapsulator.

[0444] Blend uniformity was studied for the MRM-3379 0.25 mg powder blends containing the four diluents: pregelatinized starch, microcrystalline cellulose, lactose, and mannitol (Table 13). The average and relative standard deviation (RSD) of the active ingredient content were measured. In the case of powder blends containing pregelatinized starch, in-process samples collected from the blending bottle had acceptable blend uniformity. In contrast, in powder blends containing microcrystalline cellulose, lactose, and mannitol as the diluent, the blend uniformity results trended to the lower side.Based on these observations, pregelatinized starch was selected as the first-choice diluent to develop the capsule formulation prototypes. Microcrystalline cellulose was selected as the second-choice diluent.Table 13. Blend Uniformity Results for MRM-3379 Capsules with Various Diluents98321886535vlAttorney Docket No: 254409.000968 PATENT

[0445] Two diluents, pregelatinized starch and microcrystalline cellulose, were selected to study their effects on MRM-3379 capsules product scalability, characteristics, and stability. Powder blends were prepared using pregelatinized starch or microcrystalline cellulose, sodium starch glycolate, fumed silica, and magnesium stearate with 0.25 mg, 2.5 mg, and 25 mg MRM-3379. Sodium starch glycolate, fumed silica, and magnesium stearate levels were kept at 2%, 0.5%, and 0.5%, respectively, of all the final powder blends. The prototype formulations for MRM-3379 Capsules, 0.25 mg, 2.5 mg, and 25 mg strengths are presented in Table 14 and Table 15 for pregelatinized starch and microcrystalline cellulose, respectively.Table 14. Formulations for MRM-3379 Capsules with Pregelatinized Starch99321886535vlAttorney Docket No: 254409.000968 PATENTa Total capsule fill weight does not include weight of the capsule shell. b Only a partition of the batch was encapsulated.Table 15. Formulations for MRM-3379 Capsules with Microcrystalline Cellulose100321886535vlAttorney Docket No: 254409.000968 PATENT

[0446] In the case of powder blends containing pregelatinized starch diluent, in- process samples collected from the Blending Vessel at the end of the blending operation before the addition of the lubricant (magnesium stearate) had excellent blend uniformities for the three MRM-3379 active strengths. As expected, the % RSD value decreased with an increase in the drug loading in the powder blend. Blend Uniformity data are summarized in Table 16.Table 16. Blend Uniformity Results for MRM-3379 Capsules with Pregelatinized Starch101321886535vlAttorney Docket No: 254409.000968 PATENT

[0447] In the case of powder blends containing microcrystalline cellulose diluent, the blend uniformity results trended to the lower side for the 0.25 mg powder blend (Table 17). These results were confirmed by the results obtained from the analysis of samples collected after further blending. The blend uniformity results for 2.5 mg and 25 mg powder blends were within acceptable range. However, powder blends containing microcrystalline cellulose yielded higher %RSD values than those containing pregelatinized starch. The microcrystalline cellulose powder blends appeared to be more challenging from an analytical and blend uniformity perspective. It may be attributed to potential extraction issues from the powder blend.Table 17. Blend Uniformity Results for MRM-3379 Capsules with Microcrystalline Cellulose

[0448] A dissolution test was conducted in 100 mL of 0.1N HC1 solution for MRM- 3379 capsules, 0.25 mg, and 2.5 mg strengths. A summary of the parameters used for the dissolution test is presented in Table 18.Table 18. Summary of Dissolution Testing Parameters102321886535vlAttorney Docket No: 254409.000968 PATENT

[0449] Dissolution profiles of MRM-3379 capsule formulations on stability are illustrated in Figure 16 and Figure 17 for 0.25 mg and 25 mg MRM-3379 strengths, respectively. Dissolution testing was performed on three capsules (N=3) from each capsule prototype at each stability time point. The formulations produced complete dissolution within the first 20-minute time point that was consistent throughout the stability study.

[0450] The dissolution test results at the release of MRM-3379 Capsules, 0.25 mg DS, 2.5 mg DS, and 25 mg DS, in 0.1 N HC1 are presented in Table 19 and Figure 18.Table 19. Dissolution Profiles at the Release of MRM-3379 Capsules, 0.25 mg, 2.5 mg, and 25 mg103321886535vlAttorney Docket No: 254409.000968 PATENT

[0451] No deformation of capsule shells was observed for all the above formulations in Table 14 and Table 15 stored at 25 °C ± 2°C / 60% ± 5%RH for six months and 40°C+2°C / 75%+5%RH for three months. There was also no change in the appearance of the contents of capsules filled with pregelatinized starch and microcrystalline cellulose formulations during the study period.

[0452] Both pregelatinized starch and microcrystalline cellulose formulations stored at 25°C ± 2°C / 60% ± 5%RH produced 80% dissolution of the drug substance within 60 minutes. Powder blends containing microcrystalline cellulose as the diluent were shown to be challenging during the analytical testing relative to those containing pregelatinized starch as the diluent. Powder blends containing pregelatinized starch did not exhibit any physical and chemical incompatibilities in MRM-3379 recovery studies. Thus, based on these104321886535vlAttorney Docket No: 254409.000968 PATENT observations, pregelatinized starch was selected as the diluent for the clinical capsule products. Dry blending was identified as the process of choice, as it offers a simpler manufacturing process.

[0453] The present application is not to be limited in scope by the specific embodiments described herein. Indeed, various modifications of the embodiments, in addition to those described herein, will become apparent to those skilled in the art from the foregoing description. Such modifications are intended to fall within the scope of the appended claims.

[0454] All patents, applications, publications, test methods, literature, and other materials cited herein are hereby incorporated by reference in their entirety as if physically present in this specification.105321886535vl

Claims

Attorney Docket No: 254409.000968 PATENTWhat is claimed is:

1. A method of treating fragile x syndrome (FXS) comprising administering to a subject in need thereof a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-aminepharmaceutically acceptable salt thereof.

2. The method of claim 1, wherein the subject has one or more of developmental delays, intellectual and development disabilities (IDD), intellectual deficits, learning disabilities, anxiety, depression, obsessive-compulsive behaviors, attention-deficit disorder (ADD), hyperactivity disorder, aberrant behavior, social and communication deficits, autism spectrum disorder, seizures, insomnia, obesity, and hypotonia.

3. A method of treating, reducing, or ameliorating one or more of developmental delays. IDD, intellectual deficits, learning disabilities, anxiety, depression, obsessive-compulsive behaviors, ADD, hyperactivity disorder, aberrant behavior, social and communication deficits, autism spectrum disorder, seizures, insomnia, obesity, and hypotonia in a subject having FXS, comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

4. A method of treating, reducing, or ameliorating developmental delays in a subject having FXS, comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

5. A method of treating, reducing, or ameliorating IDD, intellectual deficits, or learning disabilities in a subject having FXS, comprising administering to the subject a therapeutically106321886535vlAttorney Docket No: 254409.000968 PATENT effective amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

6. A method of treating, reducing, or ameliorating anxiety, depression, or obsessive- compulsive behaviors in a subject having FXS, comprising administering to the subject a therapeutically effective amount of 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

7. A method of treating, reducing, or ameliorating ADD, hyperactivity disorder, autism spectrum disorder, aberrant behavior, or social and communication deficits in a subject having FXS, comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

8. A method of treating, reducing, or ameliorating seizures, insomnia, obesity, or hypotonia in a subject having FXS, comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

9. A method of treating fragile X-associated Tremor / Ataxia syndrome (FXTAS), comprising administering to a subject in need of a therapeutically effective amount of 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

10. A method of improving cognitive abilities in a subject having FXS, comprising administering to the subject a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

11. The method of claim 10, wherein the subject does not experience emesis or nausea.

12. The method of claim 10, wherein the subject does not experience emesis.

13. The method of claim 10, wherein the method improves cognitive abilities in subjects having FXS and comprises administering to each of the subjects a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a107321886535vlAttorney Docket No: 254409.000968 PATENT pharmaceutically acceptable salt thereof, and less than about 10% of the subjects experience side effects.

14. The method of claim 13, wherein the side effects experienced by the subjects comprise one or more of emesis, headache, nausea, dizziness, vertigo, fatigue, diarrhea, weight loss, back pain, abdominal pain, decreased appetite, nasopharyngitis, upper respiratory tract infections, palpitations, changes in heart rate, and insomnia.

15. The method of claim 13, wherein the side effect is nausea and emesis.

16. The method of claim 13, wherein the side effect is nausea.

17. The method of claim 13, wherein the side effect is emesis.

18. The method of claim 10, wherein the method improves cognitive abilities in subjects having FXS and comprises administering to each of the subjects a therapeutically effective amount of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, and less than about 10% of the subjects experience emesis.

19. The method of claim 10, wherein the subject experiences emesis following less than about 10% of administration occurrences.

20. The method of any one of claims 10-19, wherein the improvement in cognitive abilities is measured by the National Institute of Health Toolbox Cognition Battery (NIHTB-CB) composite scores.

21. The method of any one of claims 10-20. wherein the improvement in cognitive abilities comprises improvement in one or more of reading comprehension, vocabulary comprehension, executive function, cognitive flexibility, inhibitory control, sustained attention, episodic memory, visual memory, picture sequence memory, pattern comparison, processing speed, working memory, and crystallized intelligence.

22. The method of any one of claims 10-21, wherein the method comprises improvement in academic performance, optionally comprising improvement in mathematical skills and / or language skills.108321886535vlAttorney Docket No: 254409.000968 PATENT23. The method of any one of claims 10-22. wherein the method comprises improvement in one or more of the measures selected from: i) Numerical rating scale (NRS) scores based on subject-specific behaviors within the domains of daily function and language; ii) Caregiver Global Impression of Improvement (CaGI-I) levels for the general domains of daily function and language; iii) Clinical Global Impression Improvement (CGI-I) levels for Investigator rated the general domains of daily Function and language; iv) Vineland-3 Adaptive Behavior Scale (Vineland-3) based on composite scores and domain scores from communication, daily living skills, and socialization; v) Verbal Knowledge test scores from the Stanford-Binet Intelligence Scales, Fifth Edition (SB-5); and vi) Levels of Picture Sequence Memory, Flanker Inhibitory Control and Attention, List Sorting Working Memory. Dimensional Change Card Sort, and / or Speeded Matching in the NIHTB-CB test.

24. The method of any one of claims 10-23, wherein the improvement comprises a reduction in Aberrant Behavior Checklist (ABC) scores and / or Mood Scale (ADAMS) scores.

25. The method of any one of claims 10-24, wherein the method reduces or ameliorates one or more of aberrant behavior, anxiety, depression, and the degree of the electroencephalography (EEG) abnormalities.

26. The method of any one of claims 1-25, wherein the subject is a pediatric patient.

27. The method of any one of claims 1-25, wherein the subject is under 17 years old.

28. The method of any one of claims 1-25, wherein the subject is aged 6-17 years.

29. The method of any one of claims 1-25, wherein the subject is aged 12 to less than 17 years.

30. The method of any one of claims 1-25, wherein the subject is aged 3 and up.

31. The method of any one of claims 1-25, wherein the subject is aged 9 and up.109321886535vlAttorney Docket No: 254409.000968 PATENT32. The method of any one of claims 1-25, wherein the subject is aged 2 to 11 years.

33. The method of any one of claims 1-25, wherein the subject is aged 0 days to 23 months.

34. The method of any one of claims 1-25, wherein the subject is an adult.

35. The method of any one of claims 1-25, wherein the subject is aged 18-45 years.

36. The method of any one of claims 1-25, wherein the subject is aged 65 years or older.

37. The method of any one of claims 1-25, wherein the subject has a full mutation (FM), a premutation (PM), or a methylation in the fragile X messenger ribonucleoprotein 1 (FMR I) gene.

38. The method of any one of claims 1-37, wherein the subject is male.

39. The method of any one of claims 1-38, wherein the FXS is caused by a full mutation (FM), a premutation (PM), or a methylation in the FMRI gene.

40. The method of any one of claims 1-39, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.05 mg to about 20 mg per day.

41. The method of any one of claims 1-40, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.1 mg to about 20 mg per day.

42. The method of any one of claims 1-41, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.5 mg to about 15 mg per day.

43. The method of any one of claims 1-42, wherein 5-{[5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.5 mg to about 5 mg per day.

44. The method of any one of claims 1-43, wherein 5-{[5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 1 mg to about 5 mg per day.110321886535vlAttorney Docket No: 254409.000968 PATENT45. The method of any one of claims 1-43, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.5 mg per day.

46. The method of any one of claims 1-44, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 1 mg per day.

47. The method of any one of claims 1 -44, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 2 mg per day.

48. The method of any one of claims 1-44, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 2.5 mg per day.

49. The method of any one of claims 1-44, wherein 5-{[5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 3 mg per day.

50. The method of any one of claims 1-44, wherein 5-{[5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 4 mg per day.

51. The method of any one of claims 1-44, wherein 5-{[5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 5 mg per day.

52. The method of any one of claims 1-42, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-ylJmethyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 7.5 mg per day.

53. The method of any one of claims 1-52, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a dose of about 0.002 mg / kg to about 0.2 mg / kg per day.Ill321886535vlAttorney Docket No: 254409.000968 PATENT54. The method of any one of claims 1-53, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a single dose or multiple doses per day.

55. The method of any one of claims 1-54, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered once per day.

56. The method of any one of claims 1-54, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered twice per day.

57. The method of any one of claims 1-54, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in multiple doses per day.

58. The method of any one of claims 1-54, wherein 5-{[5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in 1 - 5 doses per day.

59. The method of any one of claims 1-58, wherein 5-{[5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof is administered with food.

60. The method of claim 59, wherein 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof is administered about 30 minutes before to about 30 minutes after ingestion of food.

61. The method of claim 59 or claim 60, wherein the administration with food reduces, ameliorates, or minimizes side effects as compared to the administration of 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, more than about 30 minutes before or more than about 30 minutes after ingestion of food.112321886535vlAttorney Docket No: 254409.000968 PATENT62. The method of claim 61, wherein the side effect comprises one or more of emesis, headache, nausea, dizziness, vertigo, fatigue, diarrhea, weight loss, back pain, abdominal pain, decreased appetite, nasopharyngitis, upper respiratory tract infections, palpitations, changes in heart rate, and insomnia.

63. The method of claim 62, the side effect is nausea and emesis.

64. The method of claim 62, the side effect is nausea.

65. The method of claim 62, wherein the side effect is emesis.

66. The method of claim 59 or claim 60, wherein the administration with food delays release of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, as measured by Tmax, as compared to the administration of 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, more than about 30 minutes before or more than about 30 minutes after ingestion of food.

67. The method of claim 66, wherein the administration with food increases Tmax by about 0.5 hour to about 10 hours, as compared to the administration of 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, more than about 30 minutes before or more than about 30 minutes after ingestion of food.

68. The method of claim 66 or claim 67, wherein the administration with food increases Tmaxby about 1 hour to about 8 hours.

69. The method of claim 59 or claim 60. wherein the administration with food decreases Cmaxof 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, as compared to the administration of 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-ylJmethyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, more than about 30 minutes before or more than about 30 minutes after ingestion of food.

70. The method of claim 69, wherein the Cmaxwhen administered with food is about 10% to about 90% of the Cmaxwhen 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-113321886535vlAttorney Docket No: 254409.000968 PATENT2-amine, or a pharmaceutically acceptable salt thereof, is administered more than about 30 minutes before or more than about 30 minutes after ingestion of food.

71. The method of claim 69 or claim 70, wherein the Cmax when administered with food is about 30% to about 80% of the Cmaxwhen 5-{ L5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered more than about 30 minutes before or more than about 30 minutes after ingestion of food.

72. The method of any one of claims 69-71 , wherein the Cmax when administered with food is about 60% to about 70% of the Cmax when 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered more than about 30 minutes before or more than about 30 minutes after ingestion of food.

73. The method of claim 59 or claim 60, wherein the administration with food increases bioavailability of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, as measured by AUC, compared to the administration of the same without food.

74. The method of claim 73, wherein the AUC when administered with food is about 100% to about 150% of the AUC when 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered more than about 30 minutes before or more than about 30 minutes after ingestion of food.

75. The method of claim 73 or claim 74, wherein the AUC when administered with food is about 100% to about 120% of the AUC when 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered more than about 30 minutes before or more than about 30 minutes after ingestion of food.

76. The method of any one of claims 1-75, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, penetrates the blood-brain barrier.114321886535vlAttorney Docket No: 254409.000968 PATENT77. The method of any one of claims 1-76, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain-to-plasma concentration ratio of about 4:1 to about 6:1.

78. The method of any one of claims 1-77, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain-to-plasma concentration ratio of about 4:1 to about 5:1.

79. The method of any one of claims 1-78, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a plasma concentration at about 0.5 ng / mL to 30 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.

80. The method of any one of claims 1-79, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, has a plasma concentration at about 1 ng / mL to about 30 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.

81. The method of any one of claims 1-80, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a plasma concentration at about 1 ng / mL to about 10 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.

82. The method of any one of claims 1-81, wherein 5-{[5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a plasma concentration at about 3 ng / mL to about 10 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.

83. The method of any one of claims 1-82, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain concentration of about 4 ng / mL to about 180 ng / mL while its plasma concentration is at about 1 ng / mL to about 30 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.115321886535vlAttorney Docket No: 254409.000968 PATENT84. The method of any one of claims 1-83, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain concentration of about 12 ng / mL to about 60 ng / mL while its plasma concentration is at about 3 ng / mL to about 10 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.

85. The method of any one of claims 1-84, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain concentration of about 4 ng / mL to about 180 ng / mL about one hour after administration with a dose of about 1 mg to about 5 mg.

86. The method of any one of claims 79-85, wherein the dose is about 1 mg, about 2.5 mg, about 3 mg, or about 5 mg.

87. The method of any one of claims 1-78, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain concentration of about 5 ng / mL about one hour after administration with a dose of about 1 mg.

88. The method of any one of claims 1-78, wherein 5-{[5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain concentration of about 17 ng / mL about one hour after administration with a dose of about 2.5 mg.

89. The method of any one of claims 1-78, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a brain concentration of about 41 ng / mL in the brain about one hour after administration with a dose of about 5 mg.

90. The method of any one of claims 1-89, wherein the degree of one or more side effects resulting from administering 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin- 2-amine, or a pharmaceutically acceptable salt thereof, is decreased relative to the one or more side effects resulting from administering another PDE4 inhibitor.116321886535vlAttorney Docket No: 254409.000968 PATENT91. The method of any one of claims 1-89, wherein the incidence of one or more side effects resulting from administering 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin- 2-amine, or a pharmaceutically acceptable salt thereof, is decreased relative to the one or more side effects resulting from administering another PDE4 inhibitor.

92. The method of any one of claims 1-89, wherein the degree of one or more side effects resulting from administering 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin- 2-amine, or a pharmaceutically acceptable salt thereof, is decreased relative to the one or more side effects resulting from administering another PDE4 inhibitor at the same dose.

93. The method of any one of claims 1-89, wherein the incidence of one or more side effects resulting from administering 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin- 2-amine, or a pharmaceutically acceptable salt thereof, is decreased relative to the one or more side effects resulting from administering another PDE4 inhibitor at the same dose.

94. The method of any one of claims 1-89, wherein the degree of one or more side effects resulting from administering 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin- 2-amine, or a pharmaceutically acceptable salt thereof, is decreased relative to the one or more side effects resulting from administering another PDE4 inhibitor, wherein the administration of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and the administration of another PED4 inhibitor are at their corresponding minimum effective doses.

95. The method of any one of claims 1-89, wherein the incidence of one or more side effects resulting from administering 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin- 2-amine, or a pharmaceutically acceptable salt thereof, is decreased relative to the one or more side effects resulting from administering another PDE4 inhibitor, wherein the administration of 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and the administration of another PED4 inhibitor are at their corresponding minimum effective doses.117321886535vlAttorney Docket No: 254409.000968 PATENT96. The method of any one of claims 1-89, wherein the minimum effective concentration (MEC) in plasma for 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is lower than the MEC in plasma for another PDE4 inhibitor.

97. The method of claim 96, wherein the another PDE4 inhibitor is zatolmilast or roflumilast.

98. The method of claim 97, wherein the another PDE4 inhibitor is roflumilast.

99. The method of claim 97, wherein the another PDE4 inhibitor is zatolmilast.

100. The method of any one of claims 90-94, wherein the one or more side effects comprises one or more of emesis, headache, nausea, dizziness, vertigo, fatigue, diarrhea, weight loss, back pain, abdominal pain, decreased appetite, nasopharyngitis, upper respiratory tract infections, palpitations, changes in heart rate, and insomnia.

101. The method of claim 100. wherein the one or more side effects is nausea and emesis.

102. The method of claim 100, wherein the one or more side effects is nausea.

103. The method of claim 100. wherein the one or more side effects is emesis.

104. The method of any one of claims 1-103, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising an AUC of about 3 ng*h / mL to about 100 ng*h / mL.

105. The method of any one of claims 1-104, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising an AUC of about 6 ng*h / mL to about 60 ng*h / mL.

106. The method of any one of claims 1-105, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising an AUC of about 10 ng*h / mL to about 30 ng*h / mL.

107. The method of any one of claims 1-106, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising a Cmax of about 0.05 ng / mL to about 50 ng / mL.118321886535vlAttorney Docket No: 254409.000968 PATENT108. The method of any one of claims 1-107. wherein 5-{ f5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising a Cmax of about 0.2 ng / mL to about 20 ng / mL.

109. The method of any one of claims 1-108, wherein 5-{ |5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising a Cmaxof about 1 ng / mL to about 10 ng / mL.

110. The method of any one of claims 1-109, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising a time to reach maximum plasma concentration (Tmax) of about 0.3 hour to about 15 hours after administration.

111. The method of any one of claims 1-110, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof, has an in vivo plasma profile comprising a Tmax of about 1 hour to about 10 hours after administration.

112. The method of any one of claims 1-111, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a half-life (T1 / 2) duration of about 1 hour to about 50 hours.

113. The method of any one of claims 1-112, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a half-life (T1 / 2) duration of about 4 hours to about 10 hours.

114. The method of any one of claims 1-113, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, has a half-life decay (T1 / 2) duration of about 6 hours to about 8 hours.

115. The method of any one of claims 1-114, comprising administering 5- { [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof for at least 2 years.119321886535vlAttorney Docket No: 254409.000968 PATENT116. The method of any one of claims 1-114. comprising administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for at least 1 year.

117. The method of any one of claims 1-114, comprising administering 5-{|5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for at least 8 months.

118. The method of any one of claims 1-114, comprising administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for at least 4 months.

119. The method of any one of claims 1-114, comprising administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof for at least 3 months.

120. The method of any one of claims 1-114, comprising administering 5- { [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for about 3 months.

121. The method of any one of claims 1-114, comprising administering 5- { [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for at least 2 months.

122. The method of any one of claims 1-114, comprising administering 5- { [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for at least 1 month.

123. The method of any one of claims 1-114, comprising administering 5- { [5-(3- chlorophenyl)-6-methoxypyridin-3-ylJmethyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for 4-26 weeks.

124. The method of any one of claims 1-114, comprising administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for 8-18 weeks.120321886535vlAttorney Docket No: 254409.000968 PATENT125. The method of any one of claims 1-114. comprising administering 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for 1-90 days.

126. The method of any one of claims 1-114, comprising administering 5-{|5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for 1-30 days.

127. The method of any one of claims 1-114, comprising administering 5-{[5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof for 1-10 days.

128. The method of any one of claims 1-114, comprising administering 5-{[5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof for 1-5 days.

129. The method of any one of claims 1-128, wherein the method treats, reduces, or ameliorates the one or more of developmental delays, IDD, intellectual deficits, learning disabilities, anxiety, depression, obsessive-compulsive behaviors, ADD, hyperactivity disorder, aberrant behavior, social and communication deficits, autism spectrum disorder, seizures, insomnia, obesity, and hypotonia for at least one week after administration.

130. The method of any one of claims 1-129, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof is administered orally.

131. A pharmaceutical composition comprising about 0.1 mg to about 5 mg 5-{ [5-(3- chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.

132. The pharmaceutical composition of claim 131, further comprising one or more excipient selected from the group consisting of: i) a diluent; ii) a disintegrant;121321886535vlAttorney Docket No: 254409.000968 PATENT iii) a glidant; and iv) a lubricant.

133. The pharmaceutical composition of claim 132, wherein the diluent is present in an amount of about 80% to about 98% (w / w) of the composition.

134. The pharmaceutical composition of claim 132 or claim 133, wherein the diluent is present in an amount of about 90% to about 98% (w / w) of the composition.

135. The pharmaceutical composition of any one of claims 132 -134, wherein the diluent is present in an amount of about 94% to about 98% (w / w) of the composition.

136. The pharmaceutical composition of any one of claims 132 -135. wherein the diluent is selected from the group consisting of a sugar, dextrates, dextrin, dextrose, lactose, lactose monohydrate, mannitol, sorbitol, starch, cellulose, and modified celluloses, and any combination thereof.

137. The pharmaceutical composition of any one of claims 132 -136, wherein the diluent is starch, optionally pregelatinized starch.

138. The pharmaceutical composition of any one of claims 132 -137, wherein the disintegrant is present in an amount of about 0.5% to about 4% (w / w) of the composition.

139. The pharmaceutical composition of any one of claims 132 -138. wherein the disintegrant is present in an amount of about 1% to about 3% (w / w) of the composition.

140. The pharmaceutical composition of any one of claims 132 -139, wherein the disintegrant is selected from the group consisting of croscarmellose sodium, crospovidone, starch, sodium starch glycolate, and any combinations thereof.

141. The pharmaceutical composition of any one of claims 132 -140, wherein the disintegrant is sodium starch glycolate.

142. The pharmaceutical composition of any one of claims 132 -141, wherein the glidant is present in an amount of about 0.2% to about 1% (w / w) of the composition.122321886535vlAttorney Docket No: 254409.000968 PATENT143. The pharmaceutical composition of any one of claims 132 -142, wherein the glidant is selected from the group consisting of silicon dioxide, talc, com starch, and any combinations thereof.

144. The pharmaceutical composition of any one of claims 132 -143, wherein the glidant is silicon dioxide, optionally colloidal silicon dioxide.

145. The pharmaceutical composition of any one of claims 132 -144, wherein the lubricant is present in an amount of about 0.2% to about 1 % (w / w) of the composition.

146. The pharmaceutical composition of any one of claims 132 -145, wherein the lubricant is selected from the group consisting of talc, stearic acid, leucine, glyceryl behenate, glyceryl dibehenate, glyceryl palmitostearate, hydrogenated vegetable oil, magnesium stearate, and any combinations thereof.

147. The pharmaceutical composition of any one of claims 132 -146. wherein the lubricant is magnesium stearate.

148. The pharmaceutical composition of any one of claims 132 -147, comprising: about 96% (w / w) starch; about 2% (w / w) sodium starch glycolate; about 0.5% (w / w) silicon dioxide; and about 0.5% (w / w) magnesium stearate.

149. The pharmaceutical composition of any one of claims 132 -148, wherein the pharmaceutical composition is in an oral dosage form.

150. The pharmaceutical composition of any one of claims 132 -149, wherein the pharmaceutical composition is in a solid form.

151. The pharmaceutical composition of any one of claims 132 -150, wherein the pharmaceutical composition is in the form of a tablet, capsule, caplet, pill, granule, powder, lozenge, troche, or suppository.

152. The pharmaceutical composition of any one of claims 132 -151, wherein the pharmaceutical composition is in the form of a capsule.123321886535vlAttorney Docket No: 254409.000968 PATENT153. The pharmaceutical composition of any one of claims 132 -152, comprising about 0.5 mg of 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

154. The pharmaceutical composition of any one of claims 132 -152, comprising about 2 mg of 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

155. The pharmaceutical composition of any one of claims 132 -152, comprising about 2.5 mg of 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

156. The pharmaceutical composition of any one of claims 132 -152, comprising about 3 mg of 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

157. The pharmaceutical composition of any one of claims 132 -152, comprising about 5 mg of 5-{[5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof.

158. The pharmaceutical composition of any one of claims 132 -152, wherein the total weight of the pharmaceutical composition is between about 50 mg to about 500 mg.

159. The pharmaceutical composition of any one of claims 132 -152, wherein the total weight of the pharmaceutical composition is between about 250 mg to about 400 mg.

160. The pharmaceutical composition of any one of claims 132 -152, wherein the total weight of the pharmaceutical composition is about 335 mg.

161. The method of any one of claims 1-130, wherein 5-{ [5-(3-chlorophenyl)-6- methoxypyridin-3-ylJmethyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, is administered in a pharmaceutical composition of any one of claims 131-160.

162. The method of any one of claims 1-130 and 161, further comprising administering 5- { [5- (3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine, or a pharmaceutically124321886535vlAttorney Docket No: 254409.000968 PATENT acceptable salt thereof, or the pharmaceutical composition in combination with a training protocol.

163. The method of claim 162, wherein the training protocol is cognitive training, motor training, occupational training, language training, or other behavioral intervention.

164. A kit for treating FXS, comprising 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof, and an instruction for administration with food.

165. The kit of claim 164, wherein 5-{ [5-(3-chlorophenyl)-6-methoxypyridin-3- yl]methyl}pyrimidin-2-amine, or a pharmaceutically acceptable salt thereof is present as a pharmaceutical dosage form.

166. The kit of claim 165, wherein the dosage form comprises about 0.1 mg to about 5 mg 5- { [5-(3-chlorophenyl)-6-methoxypyridin-3-yl]methyl}pyrimidin-2-amine. or a pharmaceutically acceptable salt thereof.

167. The kit of claim 165 or claim 166, wherein the dosage form is a tablet, capsule, caplet, pill, granule, powder, lozenge, troche, or suppository.

168. The kit of any one of claims 165-167, wherein the dosage form is a capsule.

169. The kit of any one of claims 164-168, wherein the food comprises high-calorie food.

170. The kit of any one of claims 164-169, wherein the food comprises high-protein food.125321886535vl

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