WO2024013505A1

WO2024013505A1 - Ibudilast and gaboxadol for the treatment of fragile x syndrome

Info

Publication number: WO2024013505A1
Application number: PCT/GB2023/051841
Authority: WO
Inventors: David Brown; Anthony Kent HALL
Original assignee: Healx Ltd
Priority date: 2022-07-13
Filing date: 2023-07-13
Publication date: 2024-01-18

Abstract

The present invention relates to compositions and kits comprising: • (i) gaboxadol, or a pharmaceutically acceptable sal _t thereof; and • (ii) ibudilast, or a pharmaceutically acceptable salt thereof. The compositions and kits are useful in the treatment of Fragile X syndrome.

Description

IBUDILAST AND GABOXADOL FOR THE TREATMENT OF FRAGILE X SYNDROME

Field of the invention

This invention relates a composition, kit and combination therapy comprising gaboxadol and ibudilast for use in the treatment of Fragile X syndrome.

Background of the invention

Fragile X syndrome, often referred to as Fragile X, is the most common inherited cause of intellectual impairment and the most common monogenic cause of autism. It affects around 1 in 4000 males and 1 in 6000 females worldwide.

There are a wide range of characteristics associated with Fragile X, and typically males are more affected than females. One of the major characteristics associated with Fragile X syndrome is intellectual impairment, such as difficulties with cognitive, executive and language performance. Individuals with Fragile X syndrome typically have social anxiety characterised by social, emotional and communication difficulties related to extreme shyness, poor eye contact and challenges forming peer relationships. Fragile X syndrome is also associated with hyperactivity and disruptive behaviour, such as short attention span, distractibility, impulsiveness, restlessness, over-activity and sensory problems. Furthermore, individuals with Fragile X syndrome often suffer from seizures. Characteristics between patients with Fragile X syndrome may vary such that one patient may only display aggressive behaviour and anxiety issues, while another patient may only display intellectual impairment.

Fragile X syndrome arises from a mutation in a single gene called Fragile X Mental Ribonucleoprotein Gene (FMRI, also referred to as Fragile X Messenger Ribonucleoprotein). The 5' UTR of FMRI contains a CGG trinucleotide repeat that is polymorphic in the population. Once the repeats exceed 200 in number, methylation of the promoter is triggered, and this in turn causes the lack of expression of the gene and translation of its encoded protein, the Fragile X Mental Ribonucleoprotein Protein (FMRP). FMRP is an RNA-binding protein involved in different steps of mRNA metabolism, such as translational control (in soma and dendritic spines) and RNA transport.

At present, there is no approved therapy to treat Fragile X syndrome. Specifically, there is no effective therapy that is capable of treating all of the phenotypes associated with Fragile X syndrome. However, there have been considerable efforts to identify pharmacological targets to treat this disorder. In particular, Fragile X syndrome has been a frequent target of repurposing efforts as well as repositioning of drugs in development. Many different standards and methods have been applied to this task. In many cases, repurposing candidates have been identified based primarily on clinical pattern matching, while in others basic disease mechanisms have been studied extensively to identify therapeutic targets, followed by thorough preclinical validation.

Overall, efforts to treat Fragile X syndrome have led to some exciting possibilities, but no definitive successes, despite much effort. This has highlighted the need for new therapies that are capable of treating all of the phenotypes associated with Fragile X syndrome and various behavioural traits.

Gaboxadol is a GABA receptor agonist and has been known to demonstrate efficacy as a sedative, analgesic and anxiolytic. Gaboxadol is currently a non-approved compound, that has been under investigation for the treatment of sleep, FXS and Angelmans syndrome.

Ibudilast is a phosphodiesterase inhibitor and is used as an anti-inflammatory. It is approved for the treatment of asthma, and stroke in Japan and other Asian markets. Ibudilast has the systematic name 2-methyl-1-(2-propan-2-ylpyrazolo[1,5-a]pyridin-3-yl)propan-1-one.

Sulindac is a non-steroidal anti-inflammatory drug with analgesic and antipyretic activity. It is used in the treatment of pain and inflammation in rheumatic disease and other musculoskeletal disorders.

Summary of the invention

The inventors have surprisingly found that combinations of the compounds gaboxadol, and ibudilast, have a therapeutic benefit for the treatment of Fragile X syndrome. The compounds individually rescue some phenotypes associated with FXS, but do not rescue them all. It has been found by the inventors that the combination alleviates or rescues all of the phenotypes associated with Fragile X syndrome. This is of great benefit clinically as a single treatment option can be offered to all patients regardless of the symptoms and severities they are experiencing. This will make it easier for doctors, caregivers and manufacturers and meets a long-felt unmet medical need.

In a first aspect of the invention, there is provided a composition comprising:

(i) gaboxadol, or a pharmaceutically acceptable salt thereof; and

(ii) ibudilast, or a pharmaceutically acceptable salt thereof.

In a second aspect of the invention, a kit comprising:

(i) at least one dose of gaboxadol, or a pharmaceutically acceptable salt thereof; and

(ii) at least one dose of ibudilast, or a pharmaceutically acceptable salt thereof. In a third aspect of the invention, there is provided a composition comprising:

(i) gaboxadol, or a pharmaceutically acceptable salt thereof; and

(ii) ibudilast, or a pharmaceutically acceptable salt thereof; for use in the treatment of Fragile X syndrome.

In a fourth aspect of the invention, there is provided a kit comprising:

(ii) at least one dose of ibudilast, or a pharmaceutically acceptable salt thereof; for simultaneous, separate or sequential use in the treatment of Fragile X syndrome.

In a fifth aspect of the invention, there is provided a method of treating Fragile X syndrome comprising administering the patient simultaneously, separately or sequentially with:

(ii) at least one dose of ibudilast, or a pharmaceutically acceptable salt thereof.

Description of the figures

Figure 1 shows the results for Open Field Hyperactivity from gaboxadol alone, ibudilast alone and combinations of gaboxadol and ibudilast.

Figure 2 shows the results for Self-Grooming (stereotypy) from gaboxadol alone, ibudilast alone and combinations of gaboxadol and ibudilast.

Figure 3 shows the results for Novelty-Suppressed Feeding or Hyponeophagia from gaboxadol alone, ibudilast alone and combinations of gaboxadol and ibudilast.

Figure 4 shows the results for Nesting from gaboxadol alone, ibudilast alone and combinations of gaboxadol and ibudilast.

Figure 5 shows the results for Aggression from gaboxadol alone, ibudilast alone and combinations of gaboxadol and ibudilast.

Figure 6 shows the results for Novelty Object Recognition (NOR) from gaboxadol alone, ibudilast alone and combinations of gaboxadol and ibudilast.

Figure 7 shows the results for Novelty Object Location (NOL) from gaboxadol alone, ibudilast alone and combinations of gaboxadol and ibudilast.

Figure 8 shows the results for the Partition Test from gaboxadol alone, ibudilast alone and combinations of gaboxadol and ibudilast.

Figure 9 shows the results for Open Field Hyperactivity from acute versus chronic treatment with gaboxadol.

Figure 10 shows the results for Self-Grooming (stereotypy) from acute versus chronic treatment with gaboxadol.

Figure 11 shows the results for Aggression from acute versus chronic treatment with gaboxadol. Figure 12 shows the results for Open Field Hyperactivity from chronic efficacious treatment with gaboxadol.

Detailed description

As Fragile X is a syndrome, there are a number of different manifestations and symptoms in patients. These include; intellectual impairment, such as difficulties with cognitive, executive and language performance, short-term memory, executive function, visual memory and visual- spatial relationships; autism; social anxiety (i.e. difficulties in social interaction) such as poor eye contact, gaze aversion, prolonged time to commence social interaction, and challenges forming peer relationships; hyperactivity and repetitive behaviour, including very short attention spans, hypersensitivity to visual, auditory, tactile, and olfactory stimuli, distractibility, impulsiveness, restlessness and over-activity; disruptive behaviour, including fluctuating mood, irritability, self-injury and aggression; obsessive compulsive disorder (OCD); ophthalmologic problems, such as strabismus; seizures; difficulties with working memory, which involves the temporary storage of information while processing the same or other information; difficulties with phonological memory (or verbal working memory); and Fragile X-related primary ovarian insufficiency (FXPOI).

By the term "treatment" or "treating" as used herein, we refer to therapeutic (curative) treatment and/or amelioration treatment (improvement in a patient's condition).

In the present invention, combinations of gaboxadol and ibudilast and optionally sulindac are used to treat one or more of the above symptoms, and are therefore effective treatments of

Fragile X syndrome. Suitably, there is provided a combination of gaboxadol, or a pharmaceutically acceptable salt thereof, and ibudilast, or a pharmaceutically acceptable salt thereof. Suitably, there is provided a combination of gaboxadol, or a pharmaceutically acceptable salt thereof, and ibudilast, or a pharmaceutically acceptable salt thereof, and sulindac, or a pharmaceutically acceptable salt thereof.

Preferably, the combinations of gaboxadol and ibudilast and optionally sulindac are used for the treatment of Fragile X syndrome, wherein the patient is exhibiting typical symptoms of the syndrome including social anxiety, cognitive impairment, memory loss and/or disruptive behaviour. More preferably, the combinations of gaboxadol and ibudilast and optionally sulindac are used for the treatment of Fragile X syndrome, wherein the patient is exhibiting one or more of, preferably two or more of, more preferably three or more of cognitive impairment, memory loss and/or disruptive behaviour. Ibudilast has been found to be particularly effective at rescuing these such cognitive impairments. The term "cognitive impairment" has its normal meaning in the art. It refers to difficulties in retaining information, learning, concentration and judgement. It may also include difficulties in maintaining attention, language performance and visual depth perception.

The term "social anxiety" has its normal meaning in the art. It may also be termed as difficulties in social interaction or low sociability. Social anxiety may include having poor eye contact, gaze aversion, prolonged time to commence social interaction, social avoidance or withdrawal and challenges forming peer relationships.

The term "memory loss" has its normal meaning in the art. It may also be called memory impairment. It refers to an inability to retain information either short-term or long-term. It may include difficulties with cognitive, executive and language performance, executive function and visual memory. It may also include difficulties with working memory, also called short-term memory (i.e. the temporary storage of information while processing the same or other information) and difficulties with phonological memory (or verbal working memory).

The term "disruptive behaviour" has its normal meaning in the art. It may also include fluctuating mood, irritability, and self-injury.

The inventors have found that gaboxadol is particularly effective at rescuing certain symptoms of FXS; hyperactivity, stereotypy, anxiety, abnormal behaviour and aggressive behaviour. Preferably the patient is exhibiting signs of one or more of hyperactivity, stereotypy, anxiety, abnormal behaviour and aggressive behaviour. Suitably, the gaboxadol is administered to rescue or alleviate one or more of the aforementioned symptoms.

The term "hyperactivity" has its normal meaning in the art. Hyperactivity may include having very short attention spans, hypersensitivity to visual, auditory, tactile, and olfactory stimuli, d istractibi lity, impulsiveness, restlessness and/or over-activity.

The term "stereotypy" has its normal meaning in the art; the persistent repetition of an act for no obvious purpose.

The term "anxiety" has its normal meaning in the art; a feeling of worry, nervousness, or unease about something with an uncertain outcome. "Hyponeophagia" has its normal meaning in the art; the inhibition of feeding produced by a novel environment, which is used as a measure of anxiety. The term "abnormal behaviour" in the context of this invention is an indicator of hippocampal integrity and normal mouse behaviour. Such ineffectiveness is associated with an impaired function of the hippocampus. Nest building is a measure of hippocampus functioning. The hippocampus is the brain area involved in short term memory and relaying information to the cortex for long term memory storage. Damage to the hippocampus or poor connectivity or signalling within the hippocampus causes a deficit in nest building. The hippocampus is severely impacted in FXS (Bostrom et al., 2016, Neurosci Biobehav Rev. 2016 Sep;68:563-574). Therefore, nest building is a measure of hippocampal integrity and is also a measure of the general well-being and natural behaviour.

The term "aggressive behaviour" has its normal meaning in the art; any behaviour or act aimed at harming a person or animal or damaging physical property.

In one embodiment the patient is exhibiting signs of hyperactivity. Signs of hyperactivity may be assessed by use of the Aberrant Behaviour Checklist (ABC) for FXS, which is a standardized rating scale and commonly used in the field.

In one embodiment the patient is exhibiting signs of stereotypy. Signs of stereotypy may be assessed by use of the Aberrant Behaviour Checklist (ABC) for FXS.

In one embodiment the patient is exhibiting signs of anxiety. Signs of anxiety may be assessed by use of the Anxiety, Depression and Mood Scale (ADAMS), which is a standardized assessment and commonly used in the field.

In one embodiment the patient is exhibiting signs of abnormal behaviour.

In one embodiment the patient is exhibiting signs of aggressive behaviour.

In one embodiment the patient is exhibiting signs of short attention span.

In one embodiment the patient is exhibiting signs of impulsiveness.

In one embodiment the patient is exhibiting signs of one or more of hyperactivity, stereotypy, anxiety, abnormal behaviour, aggressive behaviour, short attention span or impulsiveness, preferably two or more, more preferably three or more, yet more preferably four or more of hyperactivity, stereotypy, anxiety, abnormal behaviour, aggressive behaviour, short attention span or impulsiveness. Suitably the patient is exhibiting signs of hyperactivity, stereotypy, anxiety, abnormal behaviour, aggressive behaviour, short attention span and impulsiveness. Suitably the gaboxadol, or pharmaceutically acceptable salt thereof, is for use in the treatment (such as alleviation) of short attention span, impulsiveness, anxiety and/or hyperactivity associated with FXS. Suitably the ibudilast, or pharmaceutically acceptable salt thereof, is for use in the treatment (such as alleviation) of anxiety, cognitive impairment and/or social impairment associated with FXS.

As used herein, a pharmaceutically acceptable salt is a salt with a pharmaceutically acceptable acid or base. Pharmaceutically acceptable acids include both inorganic acids such as hydrochloric, sulphuric, phosphoric, diphosphoric, hydrobromic or nitric acid and organic acids such aass citric, fumaric, maleic, malic, ascorbic, succinic, tartaric, benzoic, acetic, methanesulfonic, ethanesulfonic, salicylic, stearic, benzenesulfonic or p-toluenesulfonic acid. Pharmaceutically acceptable bases include alkali metal (e.g. sodium or potassium) and alkali earth metal (e.g. calcium or magnesium) hydroxides and organic bases such as alkyl amines, aryl amines or heterocyclic amines.

The kits or compositions according to the present invention may be administered in a variety of dosage forms. In one embodiment, it may be formulated in a format suitable for oral, rectal, parenteral, intranasal or transdermal administration or administration by inhalation or by suppository.

The kits or compositions according to the present invention may be administered orally, for example as tablets, troches, lozenges, aqueous or oily suspensions, dispersible powders or granules. Preferably, the kits or compositions are formulated such that they are suitable for oral administration, for example tablets and capsules.

The kits or compositions according to the present invention may also be administered parenterally, whether subcutaneously, intravenously, intramuscularly, intrasternally, transdermally or by infusion techniques. It may also be administered as suppositories.

The kits or compositions according to the present invention may also be administered by inhalation. An advantage of inhaled medications is their direct delivery to the area of rich blood supply in comparison to many medications taken by oral route. Thus, the absorption is very rapid as the alveoli have an enormous surface area and rich blood supply and first pass metabolism is bypassed.

The present invention also provides an inhalation device containing the kits or compositions according to the present invention. Typically said device is a metered dose inhaler (MDI), which contains a pharmaceutically acceptable chemical propellant to push the medication out of the inhaler.

The kits or compositions according to the present invention may also be administered by intranasal administration. The nasal cavity's highly permeable tissue is very receptive to medication and absorbs it quickly and efficiently. Nasal drug delivery is less painful and invasive than injections, generating less anxiety among patients. By this method absorption is very rapid and first pass metabolism is usually bypassed, thus reducing inter-patient variability. Further, the present invention also provides an intranasal device containing the kits or compositions according to the present invention.

The kits or compositions according to the present invention may also be administered by transdermal administration. For topical delivery, transdermal and transmucosal patches, creams, ointments, jellies, solutions or suspensions may be employed. The present invention therefore also provides a transdermal patch containing the kits or compositions according to the present invention.

The kits or compositions according to the present invention may also be administered by sublingual administration. The present invention therefore also provides a sub-lingual tablet comprising the kits or compositions according to the present invention.

The kits or compositions according to the present invention may also be formulated with an agent which reduces degradation of the substance by processes other than the normal metabolism of the patient, such as anti-bacterial agents, or inhibitors of protease enzymes which might be the present in the patient or in commensal or parasite organisms living on or within the patient, and which are capable of degrading the compound.

Liquid dispersions for oral administration may be syrups, emulsions and suspensions.

Suspensions and emulsions may contain as carrier, for example a natural gum, agar, sodium alginate, pectin, methylcellulose, carboxymethylcellulose, or polyvinyl alcohol. The suspension or solutions for intramuscular injections may contain, together with the active compound, a pharmaceutically acceptable carrier, e.g. sterile water, olive oil, ethyl oleate, glycols, e.g. propylene glycol, and if desired, a suitable amount of lidocaine hydrochloride.

Solutions for injection or infusion may contain as carrier, for example, sterile water or preferably they may be in the form of sterile, aqueous, isotonic saline solutions. In an embodiment of the invention, the kits or compositions according to the present invention are administered in an effective amount to treat the symptoms of Fragile X syndrome. An effective dose will be apparent to one skilled in the art, and is dependent on a number of factors such as age, sex, weight, which the medical practitioner will be capable of determining.

There is an optimum effective dosage amount of gaboxadol for treating the symptoms of FXS. Too low a dose has no effect, whereas too high a dose also does not rescue the symptoms and can even cause drowsiness and sedation.

In a preferred embodiment, the compositions according to the present invention comprise 1 mg to 160 mg of gaboxadol, preferably 10 mg to 100 mg of gaboxadol. Preferably the compositions according to the present invention comprise between 1 and 50 mg of gaboxadol, preferably between 1 and 25 mg of gaboxadol, more preferably between 1 and 20 mg of gaboxadol, more preferably between 1 and 15 mg of gaboxadol, even more preferably between 1 and 10 mg of gaboxadol, such as between 3 and 8 mg of gaboxadol, for example about 5 mg of gaboxadol. Suitably the composition comprising gaboxadol is administered once a day or twice a day, preferably twice a day.

In a preferred embodiment, the compositions according to the present invention comprise 1 mg to 300 mg of ibudilast, preferably 20 mg to 150 mg of ibudilast. Preferably the compositions according to the present invention comprise between 1 and 50 mg of ibudilast, between 1 and 40 mg of ibudilast, between 1 and 30 mg of ibudilast, between 1 and 20 mg of ibudilast, preferably between 5 and 15 mg of ibudilast, more preferably between 8 and 12 mg of ibudilast, such as about 10mg of ibudilast. Alternatively, the compositions according to the present invention comprise between 10 and 40 mg of ibudilast, preferably between 10 and 30 mg of ibudilast, between 15 and 25 mg of ibudilast, such as about 20 mg of ibudilast. Suitably the composition comprising ibudilast is administered once a day or twice a day, preferably twice a day.

In a preferred embodiment, the compositions according to the present invention comprise 5 mg to 400 mg of sulindac, preferably 50 mg to 300 mg of sulindac, most preferably 150 mg to 200 mg of sulindac.

Preferably, the total daily dose of gaboxadol, ibudilast or sulindac does not exceed the maximum daily dose recommended by the manufacturer.

Any of the above doses may be administered once a day, twice a day, three times a day or four times a day. In an embodiment, the compositions of the invention are administered at least once a day. Preferably it is administered as a single daily dose. Preferably the single daily dose comprises 5 mg to 160 mg of gaboxadol, preferably 10 mg to 100 mg of gaboxadol. Preferably the single daily dose comprises 10 mg to 300 mg ibudilast, preferably 20 mg to 150 mg of ibudilast. Preferably the single daily dose comprises 5 mg to 400 mg of sulindac, preferably 50 mg to 300 mg of sulindac, most preferably 150 mg to 200 mg of sulindac.

In an embodiment, the compositions of the invention are administered twice a day. Preferably each dose comprises 10 mg to 80 mg of gaboxadol, or 20 mg to 40 mg of gaboxadol. Preferably each dose comprises 50 mg to 200 mg ibudilast, or 100 mg to 150 mg of ibudilast. Preferably each dose comprises 5 mg to 400 mg of sulindac, preferably 50 mg to 300 mg of sulindac, most preferably 150 mg to 200 mg of sulindac.

Preferably, the dosage regime is such that the total daily dosage of gaboxadol does not exceed 160 mg.

Preferably, the dosage regime is such that the total daily dosage of ibudilast does not exceed 300 mg, more preferably 50 mg, such as 40 mg. In one aspect the total daily dosage of ibudilast is 30-40 mg.

Preferably, the dosage regime is such that the total daily dosage of sulindac does not exceed 300 mg.

In order to treat Fragile X syndrome, gaboxadol and ibudilast and optionally sulindac are used in a chronic dosage regime i.e. chronic, long-term treatment. Suitably the treatment regime is at least 4 weeks, preferably at least 6 weeks, more preferably at least 8 weeks.

The kit according to the present invention provides for the administration of more than one drug, and they can be administered simultaneous, sequentially or separately. It is not necessary that they are packed together (but this is one embodiment of the invention). It is also not necessary that they are administered at the same time. As used herein, "separate" administration means that the drugs are administered as part of the same overall dosage regimen (which could comprise a number of days), but preferably on the same day. As used herein "simultaneously" means that the drugs are to be taken together or formulated as a single composition. As used herein, "sequentially" means that the drugs are administered at about the same time, and preferably within 1 hour of each other. Preferably, the kit is administered simultaneously i.e., taken together or formulated as a single composition. Most preferably, it is formulated as a single composition.

In an embodiment of the invention, the kit is administered at least once a day. Preferably it is administered as a single daily dose. Preferably the single daily dose is administered simultaneously i.e., gaboxadol and ibudilast and optionally sulindac are taken together or formulated as a single composition. In this embodiment, most preferably, it is formulated as a single composition.

In this embodiment, preferably the kit comprises of 5 mg to 160 mg of gaboxadol, preferably 10 mg to 100 mg of gaboxadol.

In this embodiment, preferably the kit comprises of 10 mg to 300 mg of ibudilast, preferably 20 mg to 150 mg of ibudilast. It may also be administered sequentially i.e., at about the same time, and preferably within about 1 hour of gaboxadol.

In this embodiment, preferably the kit comprises of 5 mg to 400 mg of sulindac, preferably 50 mg to 300 mg of sulindac, most preferably 150 mg to 200 mg of sulindac. It may also be administered sequentially i.e., at about the same time, and preferably within about 1 hour of gaboxadol.

In an embodiment of the invention, the kit may be administered twice daily. Preferably each daily dose is administered simultaneously i.e., gaboxadol and ibudilast and optionally sulindac are taken together or formulated as a single composition. In this embodiment, most preferably, it is formulated as a single composition, which is administered twice daily.

In this embodiment, preferably the kit comprises of 10 mg to 80 mg of gaboxadol, or 20 mg to 40 mg of gaboxadol. Preferably the kit comprises between 1 and 50 mg of gaboxadol, preferably between 1 and 25 mg of gaboxadol, more preferably between 1 and 20 mg of gaboxadol, more preferably between 1 and 15 mg of gaboxadol, even more preferably between 1 and 10 mg of gaboxadol, such as between 3 and 8 mg of gaboxadol, for example about 5 mg of gaboxadol. Suitably the component of the kit comprising gaboxadol is administered once a day or twice a day, preferably twice a day

In this embodiment, preferably the kit comprises of 50 mg to 200 mg ibudilast, or 100 mg to 150 mg of ibudilast. Preferably the kit comprises between 1 and 50 mg of ibudilast, between 1 and 40 mg of ibudilast, between 1 and 30 mg of ibudilast, between 1 and 20 mg of ibudilast, preferably between 5 and 15 mg of ibudilast, more preferably between 8 and 12 mg of ibudilast, such as about 10mg of ibudilast. Alternatively, the kit comprises between 10 and 40 mg of ibudilast, preferably between 10 and 30 mg of ibudilast, between 15 and 25 mg of ibudilast, such as about 20 mg of ibudilast. Suitably the component of the kit comprising ibudilast is administered once a day or twice a day, preferably twice a day.

In this embodiment, preferably the kit comprises of 5 mg to 400 mg of sulindac, preferably 50 mg to 300 mg of sulindac, most preferably 150 mg to 200 mg of sulindac.

Each daily dose may also be administered sequentially i.e., gaboxadol and ibudilast and optionally sulindac are administered at about the same time, and preferably within about 1 hour of each other.

Suitably the dosage regimen may comprise two treatment periods. Suitably the compositions or kits of the invention may be used in a first treatment period, wherein the single or twice daily (preferably twice daily) dose of ibudilast comprises between 5 and 15 mg, more preferably between 8 and 12 mg, such as about 10mg, followed by a second treatment period wherein the single or twice daily (preferably twice daily) dose of ibudilast comprises between 15.1 and 25 mg of ibudilast, preferably between 18 and 22 mg, such as about 20 mg of ibudilast.

Suitably the first treatment period is for at least 3 weeks, preferably at least 4 weeks. Suitably the first treatment period is between 3 and 7 weeks, preferably between 3 and 6 weeks, more preferably between 3 and 5 weeks, such as about 4 weeks.

Suitably the second treatment period is for at least 3 weeks, preferably at least 4 weeks. Suitably the second treatment period is between 3 and 7 weeks, preferably between 3 and 6 weeks, more preferably between 3 and 5 weeks, such as about 4 weeks.

The present invention also relates to a method of treating Fragile X syndrome comprising administering the patient with a kit or composition as described herein. This embodiment of the invention may have any of the preferred features described above. The method of administration may be according to any of the routes described above.

The present invention also relates to the use of gaboxadol, or a pharmaceutically acceptable salt thereof, for the manufacture of a medicament for the treatment of a patient with Fragile X syndrome, wherein the patient has been administered with ibudilast or a pharmaceutically acceptable salt thereof. This embodiment of the invention may have any of the preferred features described above. The present invention also relates to the use of gaboxadol or a pharmaceutically acceptable salt thereof, for the manufacture of a medicament for the treatment of a patient with Fragile X syndrome, wherein the patient has been administered ibudilast or a pharmaceutically acceptable salt thereof and sulindac or a pharmaceutically acceptable salt thereof.

The present invention also relates to the use of gaboxadol or a pharmaceutically acceptable salt thereof, for the manufacture of a medicament for the treatment of a patient with Fragile X syndrome, wherein the patient has been administered ibudilast or a pharmaceutically acceptable salt thereof and sulindac or a pharmaceutically acceptable salt thereof, wherein the use of gaboxadol is for use in the treatment of short attention span, impulsiveness, anxiety and/or hyperactivity associated with FXS and wherein the use of ibudilast alone is for use in the treatment of anxiety, cognitive impairment and/or social impairment associated with FXS.

The present invention also relates to the use of gaboxadol or a pharmaceutically acceptable salt thereof, for the manufacture of a medicament for the treatment of a patient with Fragile X syndrome, wherein the patient has been administered ibudilast or a pharmaceutically acceptable salt thereof and sulindac or a pharmaceutically acceptable salt thereof, and wherein the dose of gaboxadol is at an amount that does not induce sedation.

The present invention also relates to a method of treatment of one or more of the phenotypes selected from hyperactivity, stereotypy, anxiety, abnormal behaviour and aggressive behaviour, the method comprising the steps: a) assessing a patient for signs of one or more of hyperactivity, stereotypy, anxiety, abnormal behaviour and aggressive behaviour; b) administering the patient with gaboxadol or a pharmaceutically acceptable salt thereof and optionally ibudilast or a pharmaceutically acceptable salt thereof. Suitably the patient has FXS. This embodiment of the invention may have any of the preferred features described above. The method of administration may be according to any of the routes described above. Suitably, the assessing is for two or more, preferably three or more, more preferably four or more of, or all of hyperactivity, stereotypy, anxiety, abnormal behaviour and aggressive behaviour.

The present invention also relates to gaboxadol or a pharmaceutically acceptable salt thereof and optionally ibudilast or a pharmaceutically acceptable salt thereof for the alleviation of one or more of hyperactivity, stereotypy, anxiety, abnormal behaviour and aggressive behaviour. Suitably the patient has FXS. This embodiment of the invention may have any of the preferred features described above. The method of administration may be according to any of the routes described above. Suitably, the alleviation is for two or more, preferably three or more, more preferably four or more of, or all of, hyperactivity, stereotypy, anxiety, abnormal behaviour and aggressive behaviour.

For the avoidance of doubt, the present invention also embraces prodrugs which react in vivo to give a compound of the present invention.

Study 1

Animals

Fmrl knockout 2 (Fmrl KO2) mice were generated by deletion of the promoter and first exon of Fmrl (Mientjes et al., 2006). The Fmrl KO2 is both, protein and mRNA null. In this study, we used Fmrl KO2 and wild-type (WT) littermates generated on a C57BL/6J background and repeatedly backcrossed onto a C57BL/6J background for more than eight generations.

Animal Housing

The Fmrl KO2 mice were housed in 4 per cage groups of the same genotype in a temperature- and humidity-controlled room with a 12-hr 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 Fmrl KO2 mice and their WT littermates. All experiments were conducted by experimenters who were blind to genotype and drug treatment. Experiments were conducted in line with the requirements of the United Kingdom Animals (Scientific Procedures) Act, 1986.

WT animals were assigned to the WT-Vehicle group, while each KO mouse was assigned to one of the KO treatment groups using randomization. At the end of the study, animals were sacrificed by cervical dislocation.

Treatment Groups

There were ten treatment groups per compound/compound combination in the study with 10 mice used per treatment group, aged P60-P74 for behavioural assays: Group 1: WT littermate mice treated with vehicle (WT-Vehicle), Group 2: Fmrl KO2 mice treated with vehicle (Fmrl KO2 - Vehicle), Group 3: Fmrl KO2 mice treated with compounds (Fmrl KO2 - gaboxadol and/or ibudilast in accordance with Table 1).

Dosing and Behavioural Assays

Fmrl KO2 and WT littermate mice were injected intraperitoneal (i.p.) with vehicle [10% DMSO in 90% (20% Captisol in Saline)] or gaboxadol or ibudilast or gaboxadol and ibudilast in combination for two weeks pre-treatment (see Table 1 for dosing regimen). All drugs were formulated and dosed in the vehicle solution. All mice were dosed 0.5h prior to behaviour testing, on the day. Administration volumes were 3.85 mL/kg, such that an adult mouse weighing 26 g received a 0.1 mL injection volume. For all test articles, the volume to be administered was based on each mouse's body weight. Treatment groups remained the same over the course of behavioural testing, such that each mouse was administered the same test condition 0.5h prior to each assay in the behavioural test battery.

Each behavioural test was performed between 8 a.m. and 4 p.m. Mice were dosed in the housing room (0.5h prior to testing) and then brought to the experimental room to acclimate for 20 minutes before testing. Animals were tested in only one behavioural task on each experimental day, and each additional behavioural test was separated by at least 2 days. For each behavioural test, each mouse was tested only once. Prior to each test, a mouse that was not included in the study was placed in the experimental apparatus for 3 minutes. 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 odour for all experimental subjects. Experimenters were blinded to mouse genotype and treatment throughout all behavioural tests and data analysis.

Open Field Hyperactivity

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. Each mouse was exposed individually to the open field in one session corresponding to 0.5 post-test article administration. The open field assay was performed using an automated system including a Noldus activity monitor chamber with the associated Ethovision software (Noldus Information Technology Inc., Leesburg, VA, USA). A mouse was placed into a corner square facing the wall and horizontal locomotor activity, measured as distance travelled in centimetres (cm) by the number of squares entered with the whole body, was recorded for 30 minutes.

Self-Grooming (stereotypy)

Stereotypy is measured by an increase in repetitive self-grooming behaviour in the Fmrl KO2 mice. After the 0.5h drug pre-treatment time elapsed, a mouse was individually placed in an empty VersaMax activity monitor chamber. Following an initial 10-minute habituation phase, self-grooming was measured for 10 minutes using an automated system with the associated VersaDat software (Accuscan Instruments, Columbus, OH, USA).

Novelty-Suppressed Feeding or Hyponeophagia

The novelty-suppressed feeding test, in which a highly palatable but novel liquid food was available for consumption in a novel environment, measured the latency to consume a defined amount of the novel food as an index of anxiety-like behaviour. Mice were food restricted overnight and tested the next morning. 20 minutes prior to the test, each mouse was individually placed into a temporary holding cage to prevent social transmission of food preferences. Testing was conducted in a chamber (30 cm length x 30 cm width x 5 cm height) with 3 white walls and a fourth wall of transparent plastic to allow observation of the mouse. A food well (1.2 cm diameter, 0.9 cm height) was glued to the white Perspex base of the test chamber. An individual mouse was placed into the chamber facing away from the food well containing sweetened condensed milk diluted 50:50 with water. The latency from placement in the test chamber to the start of a proper drinking bout, defined as drinking continuously for 3 s, was measured. Mice that did not drink the novel food during the 5-minute test received the maximal latency score.

Nesting (abnormal behaviour)

The test was performed in individual cages. Normal bedding covered the floor to a depth of 0.5 cm. Each cage was supplied with a "Nestlet", a 5 cm square of pressed cotton batting (Ancare). Mice were placed individually into the nesting cages 1 hr before the dark phase, and the results were assessed the next morning. The nests were assessed on a 5-point scale, and the amount of un-tom Nestlet was weighed. Score 1: The Nestlet was largely untouched (>90% intact).

Score 2: The Nestlet was partially torn up (50-90% remaining intact).

Score 3: The Nestlet was mostly shredded but often there was no identifiable nest site: < 50% of the Nestlet

Score 4: An identifiable, but flat nest < 90% of the Nestlet was torn up, the material was gathered into a flat nest with walls higher than the mouse height curled up on its side) on less than 50% of its circumference.

Score 5: A (near) perfect nest: >90% of the Nestlet was torn up, the nest was a crater, with walls higher than mouse body height on more than 50% of its circumference.

Aggression

Offensive aggressive behaviour was measured as the number of bite attacks, tail rattles and mounts, as well as the latency to the first attack of an unfamiliar conspecific. Mounting is a dominance behaviour that consists of attempts to climb on top of another animal. The test chamber was an empty commercial plastic cage (40 x 23 x 12 cm) with a Perspex lid to facilitate viewing of the subjects. An experimental mouse and a novel, wild type mouse (with no prior contact with the test mouse) were placed in the cage simultaneously for a 3-minute test. The total number of mounts were recorded from above with a light-sensitive video camera using the Noldus Ethovision XT system (Noldus Information Technology Inc., Leesburg, VA, USA).

Novel Object Recognition

Recognition memory of a familiar object compared to a novel object was assessed by the novel object recognition task. A Plexiglas box (26 cm length x 20 cm width x 16 cm height) and two unique objects (4-6 cm diameter x 2-6 cm height), each in duplicate, were used. Mice were habituated individually to the experimental environment by allowing them to freely explore the box, which was empty, for 20 minutes per day for 2 consecutive days before testing. The test involved two consecutive trials each 5 minutes in duration. For trial 1, two identical objects were placed in the box, and the mouse was allowed to freely explore the objects for 5 minutes. These objects would be the familiar (f) objects. For trial 2, one familiar object (f) is replaced with one novel object (n) and the mouse is allocated 5 minutes to explore. Object exploration was defined as the mouse sniffing or touching the object with its nose, vibrissa, mouth, or forepaws. Time spent near or standing on top of the objects without interacting with the object was not counted as exploration. During the trial, a mouse was required to explore the objects for a minimum of 3 seconds for that individual animal to be included in the data analysis. For the test trial, the time spent exploring the novel object and the time spent exploring the familiar object was recorded for each mouse. Social Novelty

In the three-chambered social novelty task, a subject mouse was evaluated for its preference to explore a novel versus a familiar social stimulus mouse, defined as the time spent in the chamber with the novel mouse versus the chamber with the familiar mouse. The apparatus was a rectangular three-chambered box, in which each chamber measured 20 cm (length) x 40.5 cm (width) x 22 cm (height). Dividing walls were made from clear Perspex, with openings (10 cm width x 5 cm height) that allowed access into each chamber. The apparatus was lit from below (10 lux).

The test involved three consecutive phases: habituation, sociability and social novelty. During the habituation phase, an individual test mouse was placed in the middle chamber and allowed to freely explore all three chambers, which were empty, for 5 minutes. Then, the mouse was placed in an opaque holding cage for 3 minutes, while the apparatus was prepared for the sociability phase. During the sociability phase, the mouse was allowed to freely explore all three chambers, in which one side chamber contained an unfamiliar mouse (stranger 1, with no prior contact with the test mouse) and the other side chamber was empty, for 10 minutes. The stranger mouse was enclosed in a circular wire cage (11 cm in height, bottom diameter of 10.5 cm and bars spaced 1 cm apart; Galaxy Cup, Spectrum Diversified Designs, Inc., Streetsboro, OH, USA), which allowed nose-to-nose contact between the bars. Animals serving as strangers were male mice previously habituated to placement in the cage for 10 minutes prior to testing. Then, the test mouse was placed in a holding cage for 3 minutes, while the apparatus was prepared for the social novelty phase. During the social novelty phase, the mouse was allowed to freely explore all three chambers, in which one side chamber still contained now a familiar mouse (n), and the other side chamber now contained a novel mouse (n) for 10 minutes. The Novel mouse was enclosed in a wire cage identical to that enclosing the Familiar mouse. For each phase of the test, the amount of time spent in each chamber was recorded. An entry was defined as all four paws in one chamber.

Novel Object Location (NOL)

The Object-Location Memory task is useful for assessing cognitive deficits in transgenic strains of mice and for evaluating novel chemical entities for their effect on cognition. Testing occurs in an open field arena, to which the animals are first habituated. The next day, two objects of similar material but different shapes are introduced to the arena. They are spaced roughly equidistant from each other with space in the middle for introducing the subject. In the trial, the animal is allowed to explore the arena with the two objects and shortly thereafter, the animal again encounters the two objects, except that one of them have switched positions. The trials are recorded using a camera mounted (Noldus) above the arena and scored for the percentage preference for the object in the new location using ethovision (Noldus). Data Analysis

Data were analysed using GraphPad Prism (GraphPad Software, LLC, version 8.3.0, San Diego, CA, USA). Parametric data was analysed using one-way analysis of variance (ANOVA) followed by post-hoc comparisons with Dunnett's or Sidak's multiple comparison test when appropriate. Nonparametric data was analysed using Kruskal-Wallis one-way ANOVA followed by Dunn's multiple comparisons test. An effect was considered significant if p<0.05.

Study 1 Results

Open Field Hyperactivity

Figure 1 shows the total distance travelled (cm) over one hour in Fmrl KO2 and WT mice. Data was analysed by Brown-Forsythe and Welch ANOVA followed by Dunnett's T3 multiple comparisons test. F _{(9 ,58.09)} = 111.3, p<0.0001 for all groups according to Brown-Forsythe and Welch ANOVA. Asterisks indicate the differences after Dunnett's T3 multiple comparison test; ns - not significant, **** p<0.0001 vs Fmrl KO2 vehicle group. n=10.

Fmrl KO2-vehicle treated mice were significantly more hyperactive when compared to WT vehicle treated mice. Chronic treatment with gaboxadol at 0.5 or 1.5 mg/kg normalized the distance travelled. Chronic treatment with ibudilast at 6 mg/kg BID also showed significant improvement in reduction of hyperactivity. No significant difference was found in hyperactivity in Fmrl KO2 mice treated with ibudilast at 6 mg/kg QD when compared to Fmrl KO2-vehicle mice (Figure 1).

Each combinatorial treatment with gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg QD; gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg BID; gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg QD; or gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg BID significantly reduced locomotor activity in Fmrl KO2 mice when compared to Fmrl KO2-vehicle treated mice in the open field (Figure 1). This is evidence that the combinations of gaboxadol and ibudilast are useful in the treatment of hyperactivity associated with FXS.

Self-Grooming (stereotypy)

Figure 2 shows self-grooming, a measure of stereotypy, in Fmrl KO2 and WT mice. Data was analysed by one-way ANOVA followed by Sidak's multiple comparisons test. F _{(9, 90)} = 53.33, p<0.0001 for all groups according to one-way ANOVA. Asterisks indicate the differences after Sidak's multiple comparison test; ns - not significant, **** p<0.0001 vs Fmrl KO2 vehicle group. n=10. Fmrl KO2-vehicle treated mice exhibited significantly higher levels of self-grooming when compared to WT vehicle treated mice. Chronic treatment with gaboxadol at 0.5 or 1.5 mg/kg significantly ameliorated excessive self-grooming. Chronic treatment with ibudilast at 6 mg/kg BID also significantly improved stereotypy. No significant difference was found in self-grooming in Fmrl KO2 mice treated with ibudilast at 6 mg/kg QD when compared to Fmrl KO2-vehicle mice (Figure 2).

Each combinatorial treatment with gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg QD; gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg BID; gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg QD; or gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg BID significantly improved excessive self-grooming in Fmrl KO2 mice when compared to Fmrl KO2-vehicle treated mice (Figure 2). This is evidence that the combinations of gaboxadol and ibudilast are useful in the treatment of stereotypy associated with FXS.

Novelty-Suppressed Feeding or Hyponeophagia

Figure 3 shows latency (s) of Fmrl KO2 and WT mice to eat novel food. Data was analysed by one-way ANOVA followed by Dunnett's multiple comparisons test. F _{(9, 90)} = 2068, p<0.0001 for all groups according to one-way ANOVA. Asterisks indicate the differences after Dunnett's multiple comparison test; ns - not significant, **** p<0.0001, vs Fmrl KO2 vehicle group. n=10.

Fmrl KO2-vehicle treated mice exhibited significantly higher levels of hyponeophagia when compared to WT littermate controls. Chronic treatment with gaboxadol at 0.5 or 1.5 mg/kg significantly reduced hyponeophagia. Chronic treatment with ibudilast at 6 mg/kg QD significantly reduced hyponeophagia. No significant difference was found in hyponeophagia in Fmrl KO2 mice treated with ibudilast at 6 mg/kg BID when compared to Fmrl KO2-vehicle mice (Figure 3).

Each combinatorial treatment with gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg QD; gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg BID; gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg QD; or gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg BID significantly lowered hyponeophagia in Fmrl KO2 mice when compared to Fmrl KO2-vehicle treated mice (Figure 3). This is evidence that the combinations of gaboxadol and ibudilast are useful in the treatment of anxiety associated with FXS.

Nesting (abnormal behaviour)

Figure 4 shows nest building quality in Fmrl KO2 and WT mice. Data was analysed by Kruskal-

Wallis one-way ANOVA followed by Dunn's multiple comparisons test. p<0.0001 for all groups according to Kruskal-Wallis test. Asterisks indicate the differences after Dunn's multiple comparison test; ns - not significant, *** p=0.0002, **** p<0.0001, vs Fmrl KO2 vehicle group. n=10.

Fmrl KO2-vehicle treated mice exhibited a significantly disorganised nest construction (scores 1 and 2) when compared to WT vehicle treated mice (scores 4 and 5). Chronic treatment with gaboxadol at 0.5 and 1.5 mg/kg showed significant improvement in nest construction (scores 4 and 5). No significant difference was found in nest construction in Fmrl KO2 mice treated with ibudilast at 6 mg/kg QD or 6 mg/kg BID when compared to Fmrl KO2-vehicle treated mice (Figure 4).

Each combinatorial treatment with gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg QD; gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg BID; gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg QD; or gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg BID significantly improved nest construction in Fmrl KO2 mice (scores 4 and 5) when compared to Fmrl KO2-vehicle treated mice (Figure 4). This is evidence that the combinations of gaboxadol and ibudilast are useful in improving nest building quality in Fmrl KO2 mice. Damage to the hippocampus or poor connectivity or signalling within the hippocampus, a brain area impacted in FXS (Bostrom et al., 2016), causes a deficit in nest building (Jirkof, 2014).

Aggression

Figure 5 shows the number of mounts in Fmrl KO2 and WT mice. Data was analysed by Kruskal- Wallis test followed by Dunn's multiple comparisons test. p<0.0001 for all groups according to Kruskal-Wallis test. Asterisks indicate the differences after Dunn's multiple comparison test; ns

- not significant, *** p=0.0008, ** p<0.005. n=10.

Fmrl KO2-vehicle treated mice showed a significant increase in the number of mounts when compared to WT vehicle treated mice. Chronic treatment with gaboxadol at 0.5 or 1.5 mg/kg showed significant amelioration of the aggressive phenotype. No significant difference was found in aggressive behaviour in Fmrl KO2 mice treated with ibudilast at 6 mg/kg BID or 6 mg/kg QD when compared to Fmrl KO2-vehicle mice (Figure 5).

Each combinatorial treatment with gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg QD; gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg BID; gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg QD; or gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg BID significantly reversed the aggressive phenotype when compared to Fmrl KO2-vehicle treated mice (Figure 5). This is evidence that the combinations of gaboxadol and ibudilast are useful in the treatment of aggression associated with FXS. Novel Object Recognition (NOR)

Figure 6 shows time spent investigating novel (n) and familiar (f) objects. Data was analysed by Kruskal-Wallis test followed by Dunn's multiple comparisons test. p<0.0001 for all groups according to Kruskal-Wallis test. Asterisks indicate the differences after Dunn's multiple comparison test; ns - not significant, * p=0.0114; ** p<0.006, *** p<0.001 between novel (n) and familiar (f) object. n=10.

Fmrl KO2-vehicle treated mice exhibited no preference between a familiar (f) and a novel (n) object indicating reduced learning and memory. Contrary to this, WT vehicle treated mice showed a significant preference for investigating the novel object over the familiar object. Chronic treatment of Fmrl KO2 mice with ibudilast at 6 mg/kg BID or 6 mg/kg QD significantly improved memory and learning, with these mice showing a preference for investigating the novel object over the familiar object. No significant difference was found in the preference for novel or familiar objects in Fmrl KO2 mice treated with gaboxadol at 0.5 or 1.5 mg/kg (Figure 6).

Each combinatorial treatments with gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg QD; gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg BID; gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg QD; or gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg BID significantly improved Fmrl KO2 performance in the novel object recognition task (Figure 6). This is evidence that the combinations of gaboxadol and ibudilast are useful in the treatment of memory impairment associated with FXS.

Novel Object Location (NOL)

Figure 7 shows the percent preference for investigating object in location A or object in location C. Data was analysed by Brown -Forsythe and Welch ANOVA followed by Dunnett's T3 multiple comparisons test. F _{(19, 122.6)} = 39.76, p<0.0001 for all groups according to Brown-Forsythe ANOVA. Asterisks indicate the differences after Dunnett's T3 multiple comparison test; ns - not significant, **** p<0.0001 between location A or C. n=10.

Fmrl KO2-vehicle treated mice showed no preference for the object at the novel location C indicating reduced learning and memory. Contrary to this, WT vehicle treated mice showed a significant preference for the novel location C. Chronic treatment of Fmrl KO2 mice with ibudilast at 6 mg/kg BID or 6 mg/kg QD showed a significant preference to objects at location C, ameliorating the learning and memory deficit. Fmrl KO2 mice treated with gaboxadol at 0.5 or 1.5 mg/kg showed no significant difference in the preference for the object at location C indicating no significant location memory formation (Figure 7). Each combinatorial treatment with gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg QD; gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg BID; gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg QD; or gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg BID significantly improved Fmrl KO2 performance in the novel object location task when compared to Fmrl KO2-vehicle treated mice with (Figure 7). This is evidence that the combinations of gaboxadol and ibudilast are useful in the treatment of memory impairment associated with FXS.

Partition Test

Figure 8 shows time spent investigating novel (n) and familiar (f) mice. Data was analysed by Kruskal-Wallis test followed by Dunn's multiple comparisons test. p<0.0001 for all groups according to Kruskal-Wallis test. Asterisks indicate the differences after Dunn's multiple comparison test; ns - not significant, **** p<0.0001 between novel (n) and familiar (f) mice. n=10.

Fmrl KO2-vehicle treated mice showed no preference for the novel mouse, indicating that social memory is compromised in this animal model when compared to the WT vehicle treated mice which did show a significant preference for the novel mouse. Chronic treatment of Fmrl KO2 mice with ibudilast at 6 mg/kg BID or 6 mg/kg QD significantly improved the preference for the novel mouse. Fmrl KO2 mice treated with gaboxadol at 0.5 or 1.5 mg/kg showed no significant difference for investigating the novel mouse indicating no significant improvement in social memory (Figure 8).

Each combinatorial treatment with gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg QD; gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg BID; gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg QD; or gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg BID significantly improved Fmrl KO2 preference for the novel mouse when compared to Fmrl KO2-vehicle treated mice (Figure 8). This is evidence that the combinations of gaboxadol and ibudilast are useful in the treatment of social impairment associated with FXS.

Conclusions

Gaboxadol dosed chronically at 0.5 or 1.5 mg/kg significantly reduced stereotypy, aggression, hyperactivity and hyponeophagia while improving nest building in Fmrl KO2 mice. Gaboxadol dosed at 0.5 or 1.5 mg/kg did not improve cognition or sociability as assessed by NOR, NOL and the partition test. Ibudilast dosed at 6 mg/kg BID or QD significantly improved cognition and sociability as assessed by NOR, NOL and the partition test. Ibudilast dosed at 6 mg/kg BID showed some significant improvement in reducing hyperactivity and stereotypy. Ibudilast dosed at 6 mg/kg QD showed some significant improvement in reducing hyponeophagia. All combination doses (gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg QD; gaboxadol at 0.5 mg/kg and ibudilast at 6 mg/kg BID; gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg QD; or gaboxadol at 1.5 mg/kg and ibudilast at 6 mg/kg BID) were able to significantly improve all behaviours measured when compared to the Fmrl KO2 vehicle treated mouse (hyperactivity, stereotypy, aggression, nest building quality, hyponeophagia, novel object recognition, novel object location, novel mouse recognition). Monotherapy of gaboxadol or ibudilast, at the doses described, was unable to fully rescue all behaviours measured, while the combinations of gaboxadol and ibudilast fully rescued each behavioural phenotype described here. The combinations of gaboxadol and ibudilast rescued more phenotypes in Fmrl KO2 mice than monotherapy ibudilast or gaboxadol treatment. In addition to this, no negative effects on the extent of improvement of the phenotypes were observed with combination treatment.

Study 2 - Acute versus chronic dosing of qaboxadol in Fmrl KO2 mice

Dosing and Behavioural Assays

Fmrl KO2 and WT littermate mice were be injected with vehicle [10% DMSO in 90% (20% Captisol in Saline)] or gaboxadol for two weeks pre-treatment or with an acute dose 30 minutes prior to behavioural testing on each testing day, with a three-day interval (see Table 2 for dosing regimen). Groups 6, 7, 8 (acute groups) received vehicle dosed ip QD throughout the 2-week pre-treatment period. On days 15, 19, 23, 26, 30 and 33 all groups were dosed with vehicle or gaboxadol 30 minutes prior to behaviour testing. Following the 2-week pre-treatment, all groups continued the dosing regimen, with gaboxadol or vehicle (acute groups received vehicle between behaviour test days), until completion of the study. All drugs were formulated and dosed in the vehicle solution. All mice were dosed 30 minutes prior to behaviour testing, on the day. Administration volumes were 3.85 mL/kg, such that an adult mouse weighing 26 g received a 0.1 mL injection volume. For all test articles, the volume to be administered was based on each mouse's body weight. Treatment groups remained the same over the course of behavioural testing, such that each mouse was administered the same test condition 30 minutes prior to each assay in the behavioural test battery.

Each behavioural test was performed between 8 a.m. and 4 p.m. Mice were dosed in the housing room (30 minutes prior to testing) and then, brought to the experimental room to acclimate for 20 minutes before testing. For each behavioural test, each mouse was tested only once. Prior to each test, a mouse that was not included in the study was placed in the experimental apparatus for 3 minutes. 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 odour for all experimental subjects. Experimenters were blinded to mouse genotype and treatment throughout all behavioural tests and data analysis.

Data Analysis

Data were analysed using GraphPad Prism (GraphPad Software, LLC, version 8.3.0, San Diego, CA, USA). Parametric data was analysed using one-way analysis of variance (ANOVA) followed by post-hoc comparisons with Dunnett's multiple comparison tests. An effect was considered significant if p<0.05.

Study 2 Results

Open Field Hyperactivity

Figure 9 shows the total distance travelled (cm) over one hour in Fmrl KO2 and WT mice. Data was analysed by Brown-Forsythe and Welch ANOVA followed by Dunnett's T3 multiple comparisons test. F _{(7, 40.20)} = 79.27, p<0.0001 for all groups according to Brown-Forsythe ANOVA. Asterisks indicate the differences after Dunnett's T3 multiple comparison test; ns - not significant, **** p<0.0001 vs Fmrl KO2 vehicle group. n=10. Ac-Acute, Ch-chronic.

Fmrl KO2-vehicle treated mice were significantly more hyperactive than WT vehicle treated mice. Acute treatment with gaboxadol at 0.5 mg/kg normalized the distance travelled by Fmrl KO2 mice, to levels observed in WT vehicle treated mice. While the acute treatment with gaboxadol at 0.15 or 1.5 mg/kg had no effect on hyperactivity in Fmrl KO2 mice. Locomotor activity was significantly improved in Fmrl KO2 mice by chronic treatment with gaboxadol at 0.5 or 1.5 mg/kg. Chronic treatment with gaboxadol at 0.15 mg/kg had no effect on hyperactivity in Fmrl KO2 mice. Distance travelled was significantly reduced by acute (Ac) treatment with gaboxadol at 0.5 mg/kg and chronic (Ch) treatment with gaboxadol at 0.5 or 1.5 mg/kg in Fmrl KO2 mice (Figure 9).

Self-Grooming (stereotypy)

Figure 10 shows self-grooming, a measure of stereotypy, in Fmrl KO2 and WT mice. Data was analysed by one-way ANOVA followed by Dunnett's multiple comparisons test. F _(7,72) = 67.23, p<0.0001 for all groups according to one-way ANOVA. Asterisks indicate the differences after Dunnett's multiple comparison test; ns - not significant, **** p<0.0001 vs Fmrl KO2 vehicle group. n=10. Ac-Acute, Ch-chronic.

Fmrl KO2-vehicle treated mice exhibited significantly higher levels of self-grooming when compared to WT controls. Acute treatment with gaboxadol at 0.5 mg/kg significantly ameliorated excessive self-grooming. Acute treatment with gaboxadol at 0.15 or 1.5 mg/kg had no effect. Stereotypy was also significantly improved in Fmrl KO2 mice chronically treated with gaboxadol at 0.5 or 1.5 mg/kg. Chronic treatment with gaboxadol at 0.15 mg/kg had no effect on stereotypy. Stereotypy was significantly reduced by acute (Ac) treatment with gaboxadol at 0.5 mg/kg and chronic (Ch) treatment with gaboxadol at 0.5 or 1.5 mg/kg in Fmrl KO2 mice (Figure 10).

Aggression

Figure 11 shows the number of mounts in Fmrl KO2 and WT mice. Data was analysed by Brown- Forsythe and Welch ANOVA followed by Dunnett's T3 multiple comparisons test. F _{(7, 65.74)} = 18.85, p<0.0001 for all groups according to Brown-Forsythe ANOVA. Asterisks indicate the differences after Dunnett's T3 multiple comparison test; ns - not significant, **p=0.0039, *** p=0.0001, **** p<0.0001. n=10. Ac-Acute, Ch-chronic.

Fmrl KO2-vehicle treated mice showed an increase in the number of mounts when compared to WT vehicle treated mice. Acute treatment with gaboxadol at 0.5 mg/kg showed a significant amelioration of the aggressive phenotype. Acute treatment with gaboxadol at 0.15 or 1.5 mg/kg failed to improve the aggressive behaviour. Chronic treatment with gaboxadol at 0.5 or 1.5 mg/kg significantly ameliorated the aggressive phenotype, while treatment with gaboxadol at 0.15 mg/kg had no effect in Fmrl KO2 mice. The number of mounts were significantly decreased by acute (Ac) treatment with gaboxadol at 0.5 mg/kg and chronic (Ch) treatment with gaboxadol at 0.5 or 1.5 mg/kg (Figure 11). Conclusions

Acute treatment with gaboxadol at 0.5 mg/kg and chronic treatment with gaboxadol at 0.5 or 1.5 mg/kg significantly reduced stereotypy, aggression and hyperactivity in Fmrl KO2 mice. However, acute treatment with gaboxadol at 1.5 mg/kg was ineffective.

Study 3 - Chronic dosing of qaboxadol in WT mice

The aim of this study was to determine if the chronic efficacious doses of gaboxadol at 0.5 and 1.5 mg/kg which normalized hyperactivity, aggression and stereotypy in Fmrl KO2 mice, induced any sedation in WT mice.

Fmrl KO2 and WT littermate mice were injected with vehicle [10% DMSO in 90% (20% Captisol in Saline)] or gaboxadol for two weeks pre-treatment (see Table 3). The animals were dosed with vehicle or gaboxadol 30 minutes prior to behaviour testing.

Data Analysis

Data were analysed using GraphPad Prism (GraphPad Software, LLC, version 8.3.0, San Diego, CA, USA). Parametric data was analysed using one-way analysis of variance (ANOVA) followed by post-hoc comparisons with Dunnett's T3 multiple comparison test. An effect was considered significant if p<0.05.

Study 3 Results

Open Field Hyperactivity

Figure 12 shows the total distance travelled (cm) over one hour in Fmrl KO2 and WT mice. Data was analysed by Brown-Forsythe and Welch ANOVA followed by Dunnett's T3 multiple comparisons test. F _(4,26.21) = 286.4, p<0.0001 for all groups according to Brown-Forsythe ANOVA. Asterisks indicate the differences after Dunnett's T3 multiple comparison test; ns - not significant, **** p<0.0001 vs WT vehicle group. n=10. Fmrl KO2 mice were significantly more hyperactive than WT littermate controls. Chronic treatment with gaboxadol at 0.5 mg/kg normalized the distance travelled by Fmrl KO2 mice, confirming previous results. Importantly, treatment with gaboxadol at 0.5 or 1.5 mg/kg in WT mice did not affect activity, measured as distance travelled. This data confirms that gaboxadol does not induce sedation when administered at these doses chronically in WT mice (Figure 12).

Study 4 - Phase 1b/2a study to explore the safety and target engagement of Ibudilast and Gaboxadol combination in adolescents and adults with FXS

This is a randomized, placebo-controlled, double-blind, two-period combination and dose escalation exploratory study. Subjects will enrol in an 8-week treatment phase comprised of two periods randomized between a placebo or active treatment arm. For those entering the active treatment arm, Period 1 consists of a low dose combination of ibudilast (10mg) BID with gaboxadol (5mg) BID for 4 weeks followed by Period 2 consisting of a higher dose combination of ibudilast (20mg) BID with gaboxadol (5mg) BID for 4 weeks. At the end of the Treatment Period, there will be a 2-week Follow-up Period.

To maintain the double-blind design, placebo will match in colour and size both respective doses of ibudilast (10 mg and 20 mg capsules) and gaboxadol (5mg).

Male subjects aged 13 to 40 years (inclusive) with a diagnosis of FXS consistent with their clinical evaluation and confirmed by FMR1-DNA testing showing presence of full FMRI mutation will be eligible to participate in the study. Subjects will take their assigned study drug orally.

Clinical outcomes will be assessed by:

• Biomarkers o EEG o Tobii Eye Tracking (for subcohort of participants at capable sites only)

Efficacy Measures o NIH Toolbox Cognitive Battery o Aberrant Behavior Checklist score o ADAMS

Overall Clinical Picture o Clinical Global Impressions of Improvement (CGI-I) and Severity (CGI-S) o Clinician and Caregiver completed FXS domain specific concerns

Number of Subjects

Fifteen subjects will be enrolled and randomized to treatment arm (n= 10) or concurrent placebo arm (n=5). The sample size of 15 is based on clinical considerations and considered large enough to capture possible biomarker changes and clinically relevant indications. As this is an exploratory study, the aim is to look for possible signals or trends, and all statistical analyses are considered exploratory. Subjects randomized to treatment will not be replaced if they do not complete the full Treatment Period.

Intervention Groups

Subjects will be randomly assigned to 1 of 2 treatment arms in the study; these arms will be conducted in parallel. Fifteen subjects will be enrolled and randomized to treatment arm (n=10) or concurrent placebo arm (n=5). Clinical Outcome Measures

The clinical efficacy variables used in the study are categorized into 4 domain types: Cognition, Anxiety, Behavior and Overall Clinical Picture. The table below summarizes these domains by their respective evaluative tests.

SCREENING: The trial will begin with a Screening Period from Visit 1

PERIOD 1:

Period 1 will consist of fifteen participants randomized between placebo (n=5) or a combination of ibudilast and gaboxadol treatment (n=10) arm at Visit 2.

Outcome measures will be assessed before starting treatment

Participants on the combination arm will receive ibudilast 10mg BID and gaboxadol 5mg BID

Participants will receive treatment for approximately 4 weeks until Visit 3

All safety and efficacy outcome measures will be assessed at Visit 3 PERIOD 2:

Period 2 will commence at Visit 3

Participants on the combination arm will have their ibudilast 10mg switched to 20mg BID and continue with gaboxadol 5 mg BID

Participants will receive treatment for approximately 4 weeks until Visit 4

All safety and efficacy outcome measures will be assessed at Visit 4

Participants may drop out of the trial if they experience prohibitive safety or tolerability issues as a result of the higher dose of ibudilast (there is no option for dose reduction)

FOLLOW-UP: On completion of the treatment period, subjects will enter a 2-week follow-up from Visit 4 to Visit 5.

Claims

1. A composition comprising:

(i) gaboxadol, or a pharmaceutically acceptable salt thereof; and

(ii) ibudilast, or a pharmaceutically acceptable salt thereof.

2. A kit comprising:

3. The composition of claim 1 wherein the composition comprises gaboxadol, or a pharmaceutically acceptable salt thereof, and ibudilast, or a pharmaceutically acceptable salt thereof and sulindac, or a pharmaceutically acceptable salt thereof.

4. The kit of claim 2 wherein the kit comprises at least one dose of gaboxadol, or a pharmaceutically acceptable salt thereof, and at least one dose of ibudilast, or a pharmaceutically acceptable salt thereof and at least one dose of sulindac, or a pharmaceutically acceptable salt thereof.

5. The composition or kit according to any preceding claim for use in the treatment of hyperactivity.

6. The composition or kit according to any preceding claim for use in the treatment of stereotypy.

7. The composition or kit according to any preceding claim for use in the treatment of anxiety.

8. The composition or kit according to any preceding claim for use in the treatment of abnormal behaviour.

9. The composition or kit according to any preceding claim for use in the treatment of aggressive behaviour.

10. The composition or kit according to any preceding claim for use in the treatment of short attention span.

11. The composition or kit according to any preceding claim for use in the treatment of impulsiveness.

12. The composition or kit according to any preceding claim for use in the treatment of two or more of hyperactivity, stereotypy, anxiety, abnormal behaviour, aggressive behaviour, short attention span or impulsiveness.

13. The composition or kit according to any preceding claim for use in the treatment of fragile X syndrome (FXS).

14. The composition or kit according to any preceding claim, wherein the patient is exhibiting signs of hyperactivity.

15. The composition or kit according to any preceding claim, wherein the patient is exhibiting signs of stereotypy.

16. The composition or kit according to any preceding claim, wherein the patient is exhibiting signs of anxiety.

17. The composition or kit according to any preceding claim, wherein the patient is exhibiting signs of abnormal behaviour.

18. The composition or kit according to any preceding claim, wherein the patient is exhibiting signs of aggressive behaviour.

19. The composition or kit according to any preceding claim, wherein the patient is exhibiting signs of a short attention span.

20. The composition or kit according to any preceding claim, wherein the patient is exhibiting signs of impulsiveness.

21. The composition or kit according to any preceding claim, wherein the patient is exhibiting two or more signs of hyperactivity, stereotypy, anxiety, abnormal behaviour, aggressive behaviour, short attention span or impulsiveness.

22. The composition or kit according to any preceding claim, wherein administration of the gaboxadol is by a single or twice daily dose, preferably twice daily dose.

23. The composition or kit according to claim 22, wherein the single or twice daily dose comprises between 1 and 50 mg of gaboxadol, preferably between 1 and 25 mg of gaboxadol, more preferably between 1 and 20 mg of gaboxadol, more preferably between 1 and 15 mg of gaboxadol, even more preferably between 1 and 10 mg of gaboxadol, such as between 3 and 8 mg of gaboxadol, for example about 5 mg of gaboxadol.

24. The composition or kit according to any preceding claim, wherein administration of the ibudilast is a by a single or twice daily dose, preferably twice daily dose.

25. The composition or kit according to claim 24, wherein the single or twice daily dose comprises between 1 and 50 mg of ibudilast, between 1 and 40 mg of ibudilast, between 1 and 30 mg of ibudilast, between 1 and 20 mg of ibudilast, preferably between 5 and 15 mg of ibudilast, more preferably between 8 and 12 mg of ibudilast, such as about 10mg of ibudilast.

26. The composition or kit according to claim 24, wherein the single or twice daily dose comprises between 10 and 30 mg of ibudilast, between 15 and 25 mg of ibudilast, preferably between 18 and 22 mg, such as about 20 mg of ibudilast.

27. The composition or kit according to any preceding claim, wherein the single or twice daily dose of ibudilast comprises between 5 and 15 mg, more preferably between 8 and 12 mg, such as about 10mg in a first treatment period, followed by a second treatment period wherein the single or twice daily dose of ibudilast comprises between 15.1 and 25 mg of ibudilast, preferably between 18 and 22 mg, such as about 20 mg of ibudilast.

28. The composition or kit according to claim 27 wherein the first treatment period is between 3 and 7 weeks, preferably between 3 and 6 weeks, more preferably between 3 and 5 weeks, such as about 4 weeks.

29. The composition or kit according to either claim 27 or 28 wherein the second treatment period is between 3 and 7 weeks, preferably between 3 and 6 weeks, more preferably between 3 and 5 weeks, such as about 4 weeks.

30. The kit according to any preceding claim for simultaneous, separate or sequential use in the treatment of Fragile X syndrome.

31. A method of treating Fragile X syndrome comprising administering the patient simultaneously, separately or sequentially with:

32. The method according to claim 31, having any of the additional features of claims 3 to

30.

33. Use of gaboxadol, or a pharmaceutically acceptable salt thereof, for the manufacture of a medicament for the treatment of a patient with Fragile X syndrome, wherein the patient has been administered with ibudilast, or a pharmaceutically acceptable salt thereof.

34. Use of gaboxadol, or a pharmaceutically acceptable salt thereof according to claim 33, having any of the additional features of claims 3 to 30.

35. Use of ibudilast, or a pharmaceutically acceptable salt thereof, for the manufacture of a medicament for the treatment of a patient with Fragile X syndrome, wherein the patient has been administered with gaboxadol, or a pharmaceutically acceptable salt thereof.

36. Use of ibudilast, or a pharmaceutically acceptable salt thereof according to claim 35, having any of the additional features of claims 3 to 30.