FR3149773A1 - NEW SYNERGISTIC COMBINATIONS BASED ON FENM - Google Patents

Abstract

The invention relates to a composition comprising a synergistic combination of fluoroethylnormemantine (FENM) and at least one agonist or positive modulator of the sigma-1 receptor. More particularly, the invention relates to said composition for its use as a medicament, even more particularly for its use in the treatment of a pathology selected from neurogenetic diseases of metabolic origin such as GM2 ganliosidosis, Krabbe disease, Fabry disease, type I sialidosis, Gaucher disease, Niemann-Pick disease type C, Refsum disease, cerebrotendinous xanthomatosis, adrenoleukodystrophy, or tauopathies, synucleinopathies, amyloidopathies, Alzheimer's disease, Parkinson's disease, multiple system atrophy, Huntington's disease, posterior cortical atrophy, Pick's disease, epilepsy, vascular dementia, frontotemporal dementia, dementia with Lewy bodies, amyotrophic lateral sclerosis. Figure to be published with the abstract: FIGURE 5

Description

NEW SYNERGISTIC COMBINATIONS BASED ON FENM

The invention relates to the field of neurodegenerative diseases.

The invention relates more particularly to compositions comprising a synergistic combination of 3(2-fluoroethyl)tricyclo[3.3.1.13,7]decan-1-amine (fluoroethylnormemantine, FENM) with at least one agonist or positive modulator of the sigma-1 receptor.

The invention also relates to these combinations or compositions comprising them for their use in the treatment of neurodegenerative pathologies and, more particularly, in the prevention and/or treatment of cognitive disorders of these pathologies.

The World Health Organization (WHO) estimates that by 2050 the number of people aged over 60 is expected to reach two billion. This unprecedented ageing of the world’s population suggests that chronic diseases related to ageing will put a heavy strain on health systems. Dementia is one of these. For example, the WHO estimates that the total number of people with dementia is expected to exceed 150 million by 2050.

Dementia is characterized by a deterioration of cognitive functions, particularly memory and reasoning, which impacts the patient's behavior and ability to perform everyday tasks. Dementia is a syndrome that covers pathologies with very diverse etiologies that affect different areas of the brain and/or other regions of the central nervous system and involve in particular neurodegeneration and the death of neuronal cells. Directly linked to aging, mitochondrial dysfunction and oxidative stress play a crucial role in the pathogenesis of neurodegenerative diseases. These pathologies and syndromes are also often linked to an abnormal accumulation of certain proteins and/or the accumulation of mutated and/or abnormally folded proteins as observed in Aβ amyloidosis, tauopathies, synucleinopathies, aggregation of superoxide dismutase-1 (SOD1), polyglutamine, and TDP-43 protein.

Alzheimer's disease is the most common cause of dementia and is thought to be responsible for 60-70% of cases (source: WHO).

Today, several molecules are authorized in the symptomatic treatment of Alzheimer's disease. These are anticholinesterases such as donepezil, rivastigmine, or galantamine that benefit from marketing authorizations (MA), in monotherapy, at the mild, moderate or moderately severe stage of the disease. Memantine, a non-competitive voltage-dependent antagonist of NMDA (N-methyl-D-aspartate) receptors, is authorized at the moderate and severe stages of the disease and is not authorized at the mild stage of the disease. These compounds are not recommended at the early stage of the disease, due to a lack of clinical efficacy. In addition, their effects are symptomatic and limited and have only been demonstrated in the short term (on average 6 months) in nearly two thirds of patients included in clinical studies (source, Haute Autorité de Santé, France).

Endoplasmic reticulum (ER) chaperones are known to regulate the cellular response to misfolded proteins, ER stress, and within membrane contact domains between the ER and mitochondria called MAMs (mitochondria-associated membrane), they modulate the exchanges between the two organelles. Among them, the sigma-1 receptor is a chaperone protein highly enriched in these MAM domains. Through protein-protein interactions, activation of the sigma-1 receptor directly affects not only calcium transfer to the mitochondria but also many cellular pathways (Maurice et al., 2016). Ligands selectively activating the sigma-1 receptor show potent neuroprotective properties in a number of animal models of neurodegenerative diseases (Maurice, 2021). In particular, sigma-1 receptor agonists modulate cholinergic and glutamatergic systems. The search for putative additive or synergistic effects of sigma-1 receptor agonists in combination with cholinergic or glutamatergic modulators has shown synergy with anticholinesterases such as donepezil but no synergy with NMDA receptor antagonists such as memantine (Maurice et al., 2016). WO 2017/191034 describes a positive modulator of the sigma-1 receptor derived from phosphinolactones for its use in the treatment of neurodegenerative pathologies. WO 2017/137600 describes neuroprotective effects of igmesine, a sigma-1 receptor agonist, on cognitive impairment induced by oligomerized Aβ _25-35 amyloid peptide, a pharmacological model of Alzheimer's disease. In this model, WO 2017/137600 describes the absence of synergy of igmesine with memantine to counteract the effects of Aβ _25-35 peptide. Maurice (2016) also describes the effect of PRE-084 in the Aβ _25-35 peptide injection model. WO 2014/155138 describes the synergy between donepezil and blarcamesin in the same model.

WO 2014/191424 describes ^18F -labeled FENM for labeling NMDA receptors and visualizing them by positron emission tomography to study the distribution of these receptors and their response to drug treatments. WO 2019/115833 describes FENM in the treatment of anxiety and depression-related disorders. WO 2021/234324 identifies neuroprotective effects of FENM.

Application WO 2013/064579 describes a combination of connexin blocking agents (such as meclofenamic acid) with an acetylcholinesterase inhibitor (such as donepezil) for use in the treatment of cognitive disorders.

Aducanumab is an anti-amyloid monoclonal antibody used to reduce the amyloid burden in the brain. Aducanumab was granted marketing authorization by the FDA (acronym for the United States Food and Drug Administration) in 2021 for the treatment of early or prodromal Alzheimer's disease with proven amyloid deposits. Given unreproduced results regarding less cognitive decline in treated patients, and taking into account the lack of therapeutic solutions, the marketing authorization was conditional on a re-evaluation of the product to confirm its clinical benefit (<www.fda.gov>). Approximately 35% of treated patients experienced cerebral microhemorrhages and cerebral edema (source France Alzheimer, <www.francealzheimer.org>). The cost of the treatment, which requires monthly intravenous administrations, is estimated at $56,000 per year.

The diagnosis of dementia associated with a neurodegenerative pathology or Alzheimer's disease at an early stage induces a significant demand for treatment from the patient and their entourage, with a view to stopping or slowing down the progression of the disease as early as possible. Thus, although avenues of research are currently being explored, this need is currently unmet. Also, there is a significant need for more effective treatments both on the symptoms treated and on the duration of treatment effectiveness in patients at a more advanced stage of the disease.

[Technical problem]

The invention aims to overcome the drawbacks of the prior art. In particular, the invention aims to propose a new therapy for cognitive impairment in neurodegenerative pathologies and in particular Alzheimer's disease (AD). This new therapy is based on the combined action of fluoroethylnormemantine (FENM) and at least one agonist or positive modulator of the sigma-1 receptor. The synergy of action surprisingly identified between these molecules makes it possible, on the one hand, to obtain particularly effective effects in preserving cognitive abilities, to develop new compositions that were not permitted with memantine and to reduce the doses used for these compounds. This reduction makes it possible to eliminate the risk of adverse effects or even to increase the possible duration of treatment while obtaining a greater improvement for particularly low doses. This improved efficacy makes it possible to envisage the use of this treatment, including at the early stage of the disease.

[Brief description of the invention]

The applicants have discovered quite surprisingly that the association of the effects of 3-(2-fluoroethyl)adamantan-1-amine (FENM) with those of sigma-1 receptor agonists has a synergistic effect in the treatment of cognitive symptoms in a mouse model intoxicated by intracerebral administration of oligomers of amyloid β _25-35 peptide (Aβ _25-35 ). This synergistic action is observed in cognitive tests of short-term working memory, but also of long-term contextual memory. Such synergistic effects make it possible to envisage new treatments for neurodegenerative pathologies that are more effective than those currently applied.

Accordingly, an object of the present invention relates to a synergistic combination of FENM or any of its pharmaceutically acceptable salts and at least one agonist or positive modulator of a sigma-1 receptor or any of its pharmaceutically acceptable salts.

In a particular embodiment of said synergistic combination, said at least one agonist or positive modulator of a sigma-1 receptor is selected from 2-(2-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3,5-Dichlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(2,3-Dichlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Fluorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-Fluorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Nitrophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4 benzyloxycarbamoylphenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(Pyridin-2-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyridin-3-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyridin-4-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyrimidin-2-yl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(Pyrimidin-5-yl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-aminophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-aminophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-chlorophenyl)-N-methyl-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-chlorophenyl)-2-thiono-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinan, PRE-084 (2-morpholin-4-ylethyl 1-phenylcyclohexane-1-carboxylate), (+)-pentazocine, (+)-SKF10,047, cutamesine, fluvoxamine, igmesine, OPC-14523, BD737, BHDP, pridopidine, ANAVEX1-41, ANAVEX2-73, ANAVEX3-71, SDHEA, selegiline, fluoxetine, citalopram, amitriptyline, L-687384, dipentylamine, dextromethorphan, dimethyltryptamine, opipramol or one of its pharmaceutically acceptable salts, these compounds are known positive agonists or modulators of the sigma-1 receptor.

• au moins un agoniste d’un récepteur sigma-1 sélectionné parmi le PRE-084 (2-morpholin-4-yléthyl 1-phénylcyclohexane-1-carboxylate), la cutamésine (1-[2-(3,4-diméthoxyphényl)éthyl]-4-(3-phénylpropyl)pipérazine) et l’igmésine ((5E)-N-(cyclopropylméthyl)-N-méthyl-3,6-diphényl-5-hexén-3-amine),
• au moins un modulateur positif d’un récepteur sigma-1 est 2-(3-chlorophényl)-2-oxo-3,3,5,5-tétraméthyl-[1,4,2]-oxazaphosphinane ou un de ses sels pharmaceutiquement acceptable,
• un ratio molaire agoniste ou modulateur positif d’un récepteur sigma-1/FENM inférieur ou égal à 7, ledit ratio molaire étant supérieur ou égal à 0,5.

Said synergistic combination may comprise one or more of the following characteristics, alone or in combination:

• at least one agonist of a sigma-1 receptor selected from PRE-084 (2-morpholin-4-ylethyl 1-phenylcyclohexane-1-carboxylate), cutamesine (1-[2-(3,4-dimethoxyphenyl)ethyl]-4-(3-phenylpropyl)piperazine) and igmesine ((5E)-N-(cyclopropylmethyl)-N-methyl-3,6-diphenyl-5-hexen-3-amine),
• at least one positive modulator of a sigma-1 receptor is 2-(3-chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane or a pharmaceutically acceptable salt thereof,
• a molar ratio of agonist or positive modulator of a sigma-1 receptor/FENM of less than or equal to 7, said molar ratio being greater than or equal to 0.5.

Said synergistic combination is particularly effective in counteracting the cognitive effects caused by the administration of amyloid peptide Aβ _25-35 . The synergistic combination according to the invention therefore constitutes a new treatment of interest for neurodegeneration and associated dementia. Thus, the synergistic combination according to the invention is therefore of particular interest for its use as a medicament.

More particularly, the synergistic combination according to the invention is particularly suitable for its use in the treatment of a pathology selected from neurogenetic diseases of metabolic origin, tauopathies, synucleinopathies, amyloidopathies, Alzheimer's disease, Parkinson's disease, multiple system atrophy, Huntington's disease, posterior cortical atrophy, Pick's disease, epilepsy, vascular dementia, frontotemporal dementia, dementia with Lewy bodies, amyotrophic lateral sclerosis, GM2 ganliosidosis, Krabbe's disease, Fabry's disease, sialidosis type I, Gaucher's disease, Niemann-Pick disease type C, Refsum's disease, cerebrotendinous xanthomatosis, adrenoleukodystrophy.

As shown in the experimental part, the synergistic combination according to any one of the claims is suitable for use in the treatment, prevention, reduction or slowing down of the progression of alterations in cognitive abilities in a subject suffering, suspected of suffering or considered at risk of suffering from a neurodegenerative pathology.

Another object of the present invention relates to a pharmaceutical composition comprising the above-mentioned synergistic combination.

( A ) Symptomatic effect of FENM, PRE-084 or FENM+PRE-084 combination on memory impairment induced by oligomerized Aβ _25-35 peptide in the Y-maze test; Data: mean ± standard deviation of the mean. ANOVA: F _(11,204) = 2.513, p = 0.0055, n = 10-39 per group; test performed on day 8, 24 hours after the last administration of the compound or combination; * p < 0.05, ** p < 0.01, *** p < 0.001 vs . group treated with (V+V); # p < 0.05, ### p < 0.001 vs . group treated with (Aβ _25-35 +V); Dunnett's test. ( B ) Protection scale showing the level of protection (PP) conferred by FENM (F), PRE-084 (P) or the combination FENM+PRE-084 (m). The 100% corresponds to the performance level of mice not intoxicated by Aβ _25-35 and treated with vehicle. 0% protection corresponds to the performance level of mice treated with (Aβ _25-35 +V). S: synergistic effect with a CI less than 1; V: vehicle solution.

( A ) Symptomatic effect of FENM, PRE-084 or FENM+PRE-084 combination on memory impairment induced by oligomerized Aβ _25-35 peptide in the passive avoidance test. Training took place on day 9, 48 hours after the last treatment. Retention was tested on day 10, 24 hours after training. Data: mean ± standard deviation of the mean. Kruskal-Wallis ANOVA: H = 48.69, p < 0.0001, n = 11-41; * p < 0.05, ** p < 0.01, *** p < 0.001 vs . group treated with (V+V); # p < 0.05, ### p < 0.001 vs . group treated with (Aβ _25-35 +V); Dunn's test. ( B ) Protection scale showing the level of protection (PP) conferred by FENM (F), PRE-084 (P) or the combination FENM+PRE-084 (m). The 100% corresponds to the performance level of mice treated at (V+V). 0% protection corresponds to the performance level of mice treated at (Aβ _25-35 +V). S: synergistic effect with a CI less than 1; V: vehicle solution.

( A ) Symptomatic effect of FENM, igmesine or FENM+igmesine combination on memory impairment induced by oligomerized Aβ _25-35 peptide in the Y-maze test; Data: mean ± standard deviation of the mean. ANOVA: F _(10,153) = 2.902, p = 0.0024, n = 10-20 per group; test performed on day 8, 24 hours after the last administration of the compound or combination; * p < 0.05, ** p < 0.01, *** p < 0.001 vs . group treated with (V+V); # p < 0.05, ## p < 0.01, ### p < 0.001 vs . group treated with (Aβ _25-35 +V); Dunnett's test. ( B ) Protection scale showing the level of protection (PP) conferred by FENM (F), igmesine (I) or the combination FENM+igmesine (m). The 100% corresponds to the performance level of mice treated at (V+V). 0% protection corresponds to the performance level of mice treated at (Aβ _25-35 +V). S: synergistic effect with a CI less than 1; V: vehicle solution.

( A ) Symptomatic effect of FENM, igmesine or FENM+igmesine combination on memory impairment induced by oligomerized Aβ _25-35 peptide in the passive avoidance test. Training took place on day 9, 48 hours after the last treatment. Retention was tested on day 10, 24 hours after training. Data: mean ± standard deviation of the mean. Kruskal-Wallis ANOVA: H = 28.99, p = 0.0013, n = 10-24; * p < 0.05, ** p < 0.01, *** p < 0.001 vs . (V+V) treated group; Dunn's test. ( B ) Protection scale showing the level of protection (PP) conferred by FENM (F), igmesine (I) or the combination FENM+igmesine (m). The 100% corresponds to the performance level of mice treated with (V+V). 0% protection corresponds to the performance level of mice treated with (Aβ _25-35 +V). S: synergistic effect; V: vehicle solution.

( A ) Symptomatic effect of FENM, cutamesine or FENM+cutamesine combination on memory impairment induced by oligomerized Aβ _25-35 peptide in the Y-maze test; Data: mean ± standard deviation of the mean. ANOVA: F _(10,161) = 3.144, p = 0.0011, n = 11-23 per group; test performed on day 8, 24 hours after the last administration of the compound or combination; * p < 0.05, *** p < 0.001 vs . group treated with (V+V); ## p < 0.01, ### p < 0.001 vs . group treated with (Aβ _25-35 +V); Dunnett's test. ( B ) Protection scale showing the level of protection (PP) conferred by FENM (F), cutamesin (C) or the combination FENM+cutamesin (m). The 100% corresponds to the performance level of mice treated with (V+V). 0% protection corresponds to the performance level of mice treated with (Aβ _25-35 +V). S: synergistic effect; V: vehicle solution.

( A ) Symptomatic effect of FENM, cutamesine or FENM+cutamesine combination on memory impairment induced by oligomerized Aβ _25-35 peptide in the passive avoidance test. Training took place on day 9, 48 hours after the last treatment. Retention was tested on day 10, 24 hours after training. Data: mean ± standard deviation of the mean. Kruskal-Wallis ANOVA: H = 36.49, p < 0.0001, n = 12-21; * p < 0.05, ** p < 0.01, *** p < 0.001 vs . group treated with (V+V); # p < 0.05, ## p < 0.01 vs . group treated with (Aβ _25-35 +V); Dunn's test. ( B ) Protection scale showing the level of protection (PP) conferred by FENM (F), cutamesin (C) or the combination FENM + cutamesin (m). The 100% corresponds to the performance level of mice treated with (V + V). 0% protection corresponds to the performance level of mice treated with (Aβ _25-35 + V). S: synergistic effect; V: vehicle solution.

[Description of the invention]

Definitions

In the context of the present invention, the mention of a specific drug or compound includes not only the specifically named drug or compound, but also any corresponding pharmaceutically acceptable salt, hydrate, derivative, isomer, racemate, enantiomerically pure composition, conjugate or prodrug of the active molecule of the drug or said compound. Preferably, the mention of a compound includes the specifically named compound, as well as any pharmaceutically acceptable salt, hydrate, isomer, racemate, enantiomerically pure composition of said compound. More preferably, the designation of a compound is intended to designate the compound as specifically designated per se, as well as any pharmaceutically acceptable salt thereof. Unless otherwise stated, however, the mention in mass units or in mass units per day of the amount of a compound of the composition or combination according to the invention, is understood to mean the compound designated per se.

By "pharmaceutically acceptable salts" is meant, as used herein, a pharmaceutically acceptable and relatively non-toxic inorganic or organic acid addition salt of a compound of the present invention. The pharmaceutical salt formation involves coupling an acidic, basic or zwitterionic drug molecule with a counterion to create a salt version of the drug. A wide variety of chemical species can be used in the neutralization reaction. Pharmaceutically acceptable salts of the invention therefore include those obtained by reacting the compound of interest, when functioning as a base, with an inorganic or organic acid to form a salt, for example, salts of acetic acid, nitric acid, tartaric acid, hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, methanesulfonic acid, camphorsulfonic acid, oxalic acid, maleic acid, succinic acid or citric acid. Pharmaceutically acceptable salts of the invention also include those wherein, when the compound concerned functions as an acid, said compound is reacted with a suitable base to form, for example, sodium, potassium, calcium, magnesium, ammonium or choline salts. Although most salts of a given active ingredient are bioequivalent, some may have, among other things, enhanced solubility or bioavailability properties. Salt selection is now a common standard operation in the drug development process as taught by Stahl and Wermuth in their textbook (Stahl and Wermuth).

Examples of compounds that can be used to implement a combination of FENM with at least one agonist of a sigma-1 receptor according to the invention are listed respectively in Tables 1 and 2 below.

Compound CAS Reference Number ^† FENM 1639210-26-6 FENM HBr N / A FENM HCl N / A

^† Chemical Abstracts Service database registration number. NA: not available

A preferred FENM salt is FENM hydrochloride.

A particularly preferred FENM salt is FENM hydrobromide.

Compound IUPAC Name CAS Reference Number ^† PRE-084 2-morpholin-4-ylethyl 1-phenylcyclohexane-1-carboxylate 138847-85-5 PRE-084 (hydrochloride) 2-morpholin-4-ylethyl 1-phenylcyclohexane-1-carboxylate; hydrochloride 75136-54-8 pentazocine 1,13-dimethyl-10-(3-methylbut-2-enyl)-10-azatricyclo[7.3.1.0 ^2,7 ]trideca-2(7),3,5-trien-4-ol 7361-76-4; 359-83-1 (+)SKF 10047 14-methyl-12-prop-2-enyl-12-azatetracyclo[7.5.0.0 ^1.13 .0 ^3.8 ]tetradeca-3(8),4,6-trien-6-ol 133005-41-1 cutamesin 1-[2-(3,4-dimethoxyphenyl)ethyl]-4-(3-phenylpropyl)piperazine 165377-43-5 cutamesine (dihydrochloride) 1-[2-(3,4-dimethoxyphenyl)ethyl]-4-(3-phenylpropyl)piperazine;dihydrochloride 165377-44-6 ANAVEX 2-73 (or blarcamesine hydrochloride) 1-(2,2-diphenyloxolan-3-yl) -N , N -dimethylmethanamine;hydrochloride 195615-84-0 ANAVEX 1-41 1-(5,5-diphenyloxolan-3-yl)-N,N-dimethylmethanamine 99761-13-4 ANAVEX 3-71 1-(2,8-dimethyl-1-thia-3,8-diazaspiro[4.5]decan-3-yl)-3-(1H-indol-3-yl)propan-1-one 1235733-73-9 fluvoxamine 2-[( E )-[5-methoxy-1-[4-(trifluoromethyl)phenyl]pentylidene]amino]oxyethanamine 54739-18-3 4-IBP N-(1-benzylpiperidin-4-yl)-4-iodobenzamide 155798-08-6 igmesine (E)-N-(cyclopropylmethyl)-N-methyl-3,6-diphenylhex-5-en-3-amine 140850-73-3 igmesine (hydrochloride) (E)-N-(cyclopropylmethyl)-N-methyl-3,6-diphenylhex-5-en-3-amine;hydrochloride 130152-35-1 OPC-14523 1-(3-(4-(3-Chlorophenyl)-1-piperazinyl)propyl)-5-methoxy-3,4-dihydro-2-quinolinone 145969-30-8 BD-737 [2-(3,4-Dichloro-phenyl)-ethyl]-methyl-(2-pyrrolidin-1-yl-cyclohexyl)-amine N / A BHDP 6-[(4-benzylpiperazin-1-yl)methyl]-2,3-dimethoxyphenol N / A pridopidine 4-(3-methylsulfonylphenyl)-1-propylpiperidine 346688-38-8 SDHEA [(3S,8R,9S,10R,13S,14S)-10,13-dimethyl-17-oxo-1,2,3,4,7,8,9,11,12,14,15,16-dodecahydrocyclopenta[a]phenanthren-3-yl]hydrogen sulfate 651-48-9 selegiline N-methyl-N-(1-phenylpropan-2-yl)prop-2-yn-1-amine 14611-51-9 fluoxetine N-methyl-3-phenyl-3-[4-(trifluoromethyl)phenoxy]-propan-1-amine 54910-89-3; 100568-02-3; 100568-03-4 citalopram 1-[3-(dimethylamino)propyl]-1-(4-fluorophenyl)-1,3-dihydro[3,4]benzofuran-5-carbonitrile 59729-33-8; 128196-01-0; 128196-02-1 L-687384 1'-benzylspiro[2,3-dihydro-1H-naphthalene-4,4'-piperidine] 95417-67-7 dipentylamine N-pentylpentan-1-amine 2050-92-2 dextromethorphan (1S,9S,10S)-4-methoxy-17-methyl-17-azatetracyclo[7.5.3.01,10.02,7]heptadeca-2(7),3,5-triene 125-71-3 dimethyltryptamine 2-(1H-indol-3-yl)-N,N-dimethylethanamine 61-50-7 opipramol 2-[4-(3-benzo[b][1]benzazepin-11-ylpropyl)piperazin-1-yl]ethanol 909-39-7

^† Chemical Abstracts Service database registration number. NA: not available

A preferred salt of PRE-084 is PRE-084 hydrochloride.

A preferred igmesine salt is igmesine hydrochloride. The preferred enantiomer is +(E)-N-(cyclopropylmethyl)-N-methyl-3,6-diphenylhex-5-en-3-amine.

A preferred cutamesin salt is cutamesin dihydrochloride.

Examples of positive modulators of a sigma-1 receptor usable in the synergistic combination according to the invention are listed in application WO 2017/191034 and are incorporated herein by reference to this application. These are in particular 2-(2-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3,5-Dichlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(2,3-Dichlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Fluorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-Fluorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Nitrophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4 benzyloxycarbamoylphenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(Pyridin-2-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyridin-3-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyridin-4-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyrimidin-2-yl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(Pyrimidin-5-yl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-aminophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-aminophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-chlorophenyl)-N-methyl-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-chlorophenyl)-2-thiono-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane, or a pharmaceutically acceptable salt thereof.

For the purposes of the invention, a sigma-1 receptor is a subtype of sigma receptor that is a transmembrane protein chaperone of the endoplasmic reticulum such as that encoded in humans by the SIGMAR1 gene (ENSG00000147955). The sigma-1 receptor is expressed in many types of tissues. It is particularly concentrated in certain regions of the central nervous system. It has been implicated in several phenomena, including cardiovascular function, schizophrenia, clinical depression, the effects of cocaine abuse and cancer. Thus, an agonist of a sigma-1 receptor, for the purposes of the invention, means a compound that binds to the protein encoded by the human SIGMAR1 gene mentioned above or one of its homologues or any other orthologous protein, for example in mice or rats. A sigma-1 receptor agonist compound can be easily identified according to methods known to those skilled in the art. For example, a sigma-1 receptor agonist, within the meaning of the invention, comprises compounds that competitively displace the binding of a sigma-1 radioligand and induce the activity of the sigma-1 receptor, such as the dissociation of the BiP/sigma-1 receptor complex in a cell line (Hayashi & Su, Cell, 2007). In a particular embodiment, a sigma-1 receptor agonist is capable of competitively displacing cutamesine radiolabeled with carbon 11, this competition being able to be identified and quantified in vivo by dynamic positron emission tomography (PET scan) well known to those skilled in the art. A positive modulator of the sigma-1 receptor does not displace the binding of a sigma-1 radioligand, but will induce an increase in the activity of this receptor and, for example, a dissociation of the BiP/sigma-1 receptor complex can be detected. Thus, a person skilled in the art can easily identify a positive agonist or modulator of the sigma-1 receptor capable of being combined with FENM. A sigma-1 receptor agonist may have a Ki of between 0.1 nM and 2000 nM. Preferably, the agonist of a sigma-1 receptor has a Ki of less than 1000 nM, less than 500 nM, less than 100 nM, and even more preferably less than 50 nM for the sigma-1 receptor. Preferably, a positive agonist or modulator of a sigma-1 receptor capable of being combined with FENM has a selective activity on said sigma-1 receptor. Thus, a positive agonist or modulator of a sigma-1 receptor capable of being combined with FENM has a significant affinity or a higher modulatory activity of a sigma-1 receptor superior by at least 1, 2, 3, 4, or even 5 orders of magnitude, or more, compared to another agonist or modulator activity. In particular, a positive agonist or modulator of a sigma-1 receptor capable of being combined with FENM does not have a significant affinity or a significant modulatory activity for another receptor or enzyme of the central nervous system. Even more particularly, within the synergistic combination according to the invention, said positive agonist or modulator of a sigma-1 receptor is not donepezil.

Particularly preferred positive agonists or modulators of the sigma-1 receptor are selected from: 2-(2-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3,5-Dichlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(2,3-Dichlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Fluorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-Fluorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Nitrophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4 benzyloxycarbamoylphenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(Pyridin-2-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyridin-3-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyridin-4-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyrimidin-2-yl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(Pyrimidin-5-yl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-aminophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-aminophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-chlorophenyl)-N-methyl-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-chlorophenyl)-2-thiono-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinan, PRE-084, (+)-pentazocine, (+)-SKF10,047, cutamesine, fluvoxamine, igmesine, OPC-14523, BD-737, BHDP, pridopidine, ANAVEX1-41, ANAVEX 2-73, ANAVEX 3-71, dehydroepiandrosterone sulfate (SDHEA), selegiline, fluoxetine, citalopram, amitriptyline, L-687384, dipentylamine, dextromethorphan, dimethyltryptamine, opipramol or a pharmaceutically acceptable salt thereof.

The term "combination" as used herein refers to a treatment in which at least FENM and at least one agonist of a sigma-1 receptor are co-administered to a subject to together cause a biological effect. In a combination therapy according to the invention, these at least two compounds may be administered together or separately, at the same time or sequentially. In particular, FENM and said at least one agonist of a sigma-1 receptor may be administered following different routes and/or administration protocols. Accordingly, although they may be formulated together, the compounds as elements of a combination as used herein may also be formulated separately. For example, FENM may be administered orally and said at least one agonist of a sigma-1 receptor of the combination according to the invention may be injected into said subject, for example, intravenously, subcutaneously or transdermally. In another embodiment, for example, FENM may be administered orally and said at least one agonist of a sigma-1 receptor may also be administered orally to said subject concomitantly or in a time-shifted manner. Preferably, the sequence of administration of the active ingredients of the combination (FENM and said at least one agonist of a sigma-1 receptor) is such that said active ingredients or their active metabolite(s) exert their biological effects at the same time, so that the subject benefits from the maximum effect of said combination. Thus, in a particularly preferred manner, FENM and said at least one agonist of a sigma-1 receptor are administered so as to reach their maximum concentration in the plasma or the cerebrospinal fluid, preferably the cerebrospinal fluid, at the same time.

The term synergy applied to the combinations according to the invention means combinations for which the physiological or behavioral effects observed, for example pro-mnesic or anti-amnesic, or known for each of the active ingredients of said combination are added or multiplied when used in such a way that their physiological effects interact. This synergy effect makes it possible in particular to obtain pro-mnesic or anti-amnesic effects at doses at which the active ingredients applied in monotherapies would have no effect or a limited effect, which can make it possible to reduce the side effects and/or to avoid or reduce the duration of dose increase protocols. In addition, this synergy between the effects of the compounds of the combination according to the invention also makes it possible to potentiate these pro-mnesic or anti-amnesic effects or to improve complex types of memory as shown in the experimental part. Methods for analyzing the interaction between two molecules and determining the synergistic effect of a combination of compounds are well known to those skilled in the art. An example is the analysis of isobolograms and the determination of the combination index according to the principles set out by Fraser (1872) and as implemented, for example, by Martin et al . (2020).

By “subject” is meant herein any member of the animal kingdom, preferably mammals and even more preferably humans. A subject in need of the combinatorial treatments of the invention is defined as a subject suffering, suspected of suffering or considered at risk of suffering from a neurodegenerative pathology leading to dementia and associated cognitive disorders. These pathologies are, for example, neurogenetic diseases of metabolic origin such as GM2 ganliosidosis, Krabbe disease, Fabry disease, sialidosis type I, Gaucher disease, Niemann-Pick disease type C, Refsum disease, cerebrotendinous xanthomatosis, adrenoleukodystrophy, tauopathies, synucleinopathies, amyloidopathies, Alzheimer's disease, Parkinson's disease, multiple system atrophy, Huntington's disease, posterior cortical atrophy, Pick's disease, epilepsy, vascular dementia, frontotemporal dementia, dementia with Lewy bodies, amyotrophic lateral sclerosis. The compositions, combinations and methods of the present invention are particularly suitable for the treatment of cognitive disorders associated with early, moderate or advanced Alzheimer's disease. Thus, in a particular embodiment, said subject suffers from, is suspected of suffering from or is considered at risk of suffering from early, moderate or advanced Alzheimer's disease. In another particular embodiment, said subject suffers from, is suspected of suffering from or is considered at risk of suffering from cognitive disorders associated with early, moderate or advanced Alzheimer's disease, preferably from cognitive disorders associated with early Alzheimer's disease.

As used herein, the term “treatment” includes therapy, prevention, prophylaxis, delay or reduction of symptoms caused by or causes of the above diseases or disorders. The term treatment includes, but is not limited to, controlling the progression of the disease and associated symptoms. The term treatment includes, but is not limited to, protecting against the effects of toxicity caused by amyloid-β, or reducing or delaying such effects in treated subjects. The term treatment particularly refers to ameliorating, arresting or delaying the progression of cognitive symptoms of the above diseases.

Combination of FENM and at least one agonist or positive modulator of a sigma-1 receptor

As shown in the experimental data presented below, a synergistic interaction of the neuroprotective effects of FENM and sigma-1 receptor agonists was discovered, resulting in an improvement of cognitive symptoms in a pharmacological animal model of Alzheimer's disease. The protective effect of this combination against cognitive decline induced by the administration of amyloid peptide Aβ _25-35 is observed for both short-term working memory and long-term memory.

Thus, in a first aspect, the invention relates to a synergistic combination of FENM or any of its pharmaceutically acceptable salts and at least one agonist or positive modulator of a sigma-1 receptor or any of its pharmaceutically acceptable salts.

The sigma-1 agonists tested in the experimental part are of very different structure, so the data presented illustrate that a synergy of the effects of FENM and sigma-1 receptor agonists can be obtained regardless of the nature of the sigma-1 agonist concerned. Furthermore, since positive modulators of the sigma-1 receptor behave in vivo , particularly in the Aβ _25-35 model, as agonists (Maurice et al. 2019), they can be substituted for agonists.

In a particular embodiment, the synergistic combination of FENM or any of its pharmaceutically acceptable salts and at least one agonist or positive modulator of a sigma-1 receptor or any of its pharmaceutically acceptable salts comprises at least one agonist of a sigma-1 receptor selected from: 2-(2-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3,5-Dichlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(2,3-Dichlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Fluorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-Fluorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Nitrophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4 benzyloxycarbamoylphenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(Pyridin-2-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyridin-3-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyridin-4-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyrimidin-2-yl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(Pyrimidin-5-yl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-aminophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-aminophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-chlorophenyl)-N-methyl-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-chlorophenyl)-2-thiono-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinan, PRE-084, (+)-pentazocine, (+)-SKF10,047, cutamesine, fluvoxamine, igmesine, OPC-14523, BD-737, BHDP, pridopidine, ANAVEX1-41, ANAVEX 2-73, ANAVEX 3-71, SDHEA, selegiline, fluoxetine, citalopram, amitriptyline, L-687384, dipentylamine, dextromethorphan, dimethyltryptamine, opipramol or a pharmaceutically acceptable salt thereof, or one of their mixture.

In a particular embodiment, the synergistic combination of FENM or any of its pharmaceutically acceptable salts and at least one agonist or positive modulator of a sigma-1 receptor or any of its pharmaceutically acceptable salts comprises at least two agonist(s) or positive modulator(s) of a sigma-1 receptor selected from: 2-(2-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3,5-Dichlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(2,3-Dichlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Fluorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-Fluorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Nitrophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4 benzyloxycarbamoylphenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(Pyridin-2-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyridin-3-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyridin-4-yl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(Pyrimidin-2-yl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(Pyrimidin-5-yl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-aminophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-aminophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-chlorophenyl)-N-methyl-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-chlorophenyl)-2-thiono-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane, PRE-084, (+)-pentazocine, (+)-SKF10,047, cutamesine, fluvoxamine, igmesine, OPC-14523, BD-737, BHDP, pridopidine, ANAVEX1-41, ANAVEX 2-73, ANAVEX 3-71, SDHEA, selegiline, fluoxetine, citalopram, amitriptyline, L-687384, dipentylamine, dextromethorphan, dimethyltryptamine, opipramol or a pharmaceutically acceptable salt thereof.

In a particular embodiment, said at least one agonist of a sigma-1 receptor is selected from PRE-084 (IUPAC name: 2-morpholin-4-ylethyl 1-phenylcyclohexane-1-carboxylate), igmesine (IUPAC name: (E)-N-(cyclopropylmethyl)-N-methyl-3,6-diphenylhex-5-en-3-amine), cutamesine (IUPAC name: 1-[2-(3,4-dimethoxyphenyl)ethyl]-4-(3-phenylpropyl)piperazine), or any of their pharmaceutically acceptable salts.

In a particular embodiment, said at least one positive modulator of a sigma-1 receptor is 2-(3-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane or any of their pharmaceutically acceptable salts.

As mentioned, the synergistic effect observed for the combinations of the invention makes it possible to envisage using, in humans, the minimum doses or even doses lower than the doses at which the sigma-1 inhibitors are used or have been tested in humans.

Thus, in a particular embodiment, in the synergistic combination according to the invention, the at least one agonist of a sigma-1 receptor is igmesine and is administered at a dose less than or equal to 20 mg per day, less than or equal to 15 mg per day, less than or equal to 10 mg per day, less than or equal to 8 mg per day, less than or equal to 6 mg per day, less than or equal to 5 mg per day, less than or equal to 4 mg per day, less than or equal to 3 mg per day, or even less than or equal to 2 mg per day but always sufficient to observe a beneficial effect of the combination on the cognitive abilities of the subject. In another particular embodiment, in the synergistic combination according to the invention, the at least one agonist of a sigma-1 receptor is cutamesine and is administered at a dose of less than or equal to 50 mg per day, less than or equal to 25 mg per day, less than or equal to 10 mg per day or even less than 5 mg per day, but always sufficient to observe a beneficial effect of the combination on the cognitive abilities of the subject. In another particular embodiment, in the synergistic combination according to the invention, the at least one acetylcholinesterase inhibitor is PRE-084 and is administered at a dose of less than or equal to 50 mg per day, less than or equal to 25 mg per day, less than or equal to 10 mg per day or even less than 5 mg per day, but always sufficient to observe a beneficial effect of the combination on the cognitive abilities of the subject.

In a particular embodiment, in the synergistic combination according to the invention, the at least one agonist of a sigma-1 receptor is igmesine and is administered at a dose of between 0.030 mg/kg per day and 0.14 mg/kg per day, between 0.06 mg/kg per day and 0.11 mg/kg per day, or even between 0.07 mg/kg and 0.09 mg/kg per day considering a human subject with an average weight of 70 kg, as considered in the guidelines of the health authorities. In another particular embodiment, in the synergistic combination according to the invention, the at least one agonist of a sigma-1 receptor is cutamesine and is administered at a dose of between 0.071 mg/kg per day and 0.71 mg/kg per day, considering a human subject with an average weight of 70 kg. In another particular embodiment, in the synergistic combination according to the invention the at least one acetylcholinesterase inhibitor is PRE-084 and is administered at a dose of between 0.071 mg/kg per day and 0.71 mg/kg per day, considering a human subject with an average weight of 70 kg, as considered in the guidelines of the health authorities.

In a particular embodiment, said at least one positive modulator of a sigma-1 receptor is 2-(3-chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane and is administered at a dose less than or equal to 50 mg per day, less than or equal to 25 mg per day, less than or equal to 10 mg per day or even less than 5 mg per day, but always sufficient to observe a beneficial effect of the combination on the cognitive abilities of the subject.

In a particular embodiment, FENM, in the synergistic combination according to the invention, is used at a dose less than or equal to 80 mg per day, less than or equal to 40 mg per day, less than or equal to 20 mg per day, less than or equal to 15 mg per day, less than or equal to 10 mg per day, less than or equal to 5 mg per day, less than 4 mg per day, less than 3 mg per day, less than 2 mg per day, or even less than or equal to 1 mg, or even lower, but always sufficient to observe a beneficial effect of the combination on the cognitive abilities of the subject.

In another particular embodiment, FENM, in the synergistic combination according to the invention, is used at a dose less than or equal to 1.1 mg/kg per day, less than or equal to 0.6 mg/kg per day, less than or equal to 0.29 mg per day, less than or equal to 0.21 mg/kg per day, less than or equal to 0.14 mg/kg per day, less than or equal to 0.07 mg/kg per day, less than 0.06 mg/kg per day, less than 0.04 mg/kg per day, less than 0.03 mg/kg per day, or even less than or equal to 0.01 mg/kg per day, or even lower, considering a human subject with an average weight of 70 kg, as considered in the guidelines of the health authorities, but still sufficient to observe a beneficial effect of the combination on the cognitive abilities of the subject.

The person skilled in the art will know how to adapt the dose to be administered according to the mass of the subject.

Thus, in a particular embodiment of the synergistic combination of FENM and at least one agonist or positive modulator of a sigma-1 receptor according to the invention, the agonist (or positive modulator) sigma-1/FENM molar ratio is less than or equal to 7, less than or equal to 6, less than or equal to 5, less than or equal to 4, less than or equal to 3, preferably less than or equal to 2, said agonist (or positive modulator) molar ratio of a sigma-1 receptor/FENM being greater than or equal to 0.5. In a particularly preferred manner, said agonist (or positive modulator) molar ratio of a sigma-1 receptor/FENM is less than 2 and greater than or equal to 0.5. In another particular embodiment, said agonist of a sigma-1 receptor is igmesin, and the igmesin/FENM molar ratio is less than or equal to 7, less than or equal to 6, less than or equal to 5, less than or equal to 4, is less than or equal to 3, preferably less than or equal to 2. Said igmesin/FENM molar ratio being greater than or equal to 0.1. In a particularly preferred manner, said igmesin/FENM molar ratio is less than 2 and greater than or equal to 0.5. In another particular embodiment, said agonist of a sigma-1 receptor is igmesin, and the igmesin/FENM molar ratio is less than or equal to 7, less than or equal to 6, less than or equal to 5, less than or equal to 4, is less than or equal to 3, preferably less than or equal to 2, said igmesin/FENM molar ratio being greater than or equal to 0.5. In a particularly preferred manner, said igmesin/FENM molar ratio is less than 2 greater than or equal to 0.5. In another particular embodiment, said agonist of a sigma-1 receptor is PRE-084, and the molar ratio PRE-084/FENM is less than or equal to 7, less than or equal to 6, less than or equal to 5, less than or equal to 4, is less than or equal to 3, preferably less than or equal to 2. Said molar ratio PRE-084/FENM being greater than or equal to 0.1. In a particularly preferred manner, said molar ratio PRE-084/FENM is less than 2 and greater than or equal to 0.5. In another particular embodiment, said agonist of a sigma-1 receptor is cutamesin, and the molar ratio cutamesin/FENM is less than or equal to 7, less than or equal to 6, less than or equal to 5, less than or equal to 4, is less than or equal to 3, preferably less than or equal to 2. Said molar ratio cutamesin/FENM being greater than or equal to 0.1. Particularly preferably, said cutamesine/FENM molar ratio is less than 2 and greater than or equal to 0.5.

As mentioned above, preferably, the above-mentioned ratios are achieved in plasma or cerebrospinal fluid. A person skilled in the art will be able to determine the adequate doses of FENM and of the at least one agonist or positive modulator of a sigma-1 receptor to be administered to the subject so as to achieve these molar ratios, in terms of Cmax, in the target compartment of the body depending on the Cmax of each of the active ingredients of the combination. Separate administration has the advantage of allowing precise consideration of the pharmacokinetic and pharmacodynamic characteristics (PK/PD data) of each of the active ingredients of the combination, in particular in the case of very different properties between the active ingredients of the combination according to the invention.

The cognitive abilities of human subjects and their evolution can be measured by tests well known to those skilled in the art. Commonly used tests for cognitive assessment of human subjects include, in English terminology, the Mini-Mental State Examination (MMSE or Folstein test), Modified Mini-Mental State Examination (or 3MS scale), Abbreviated Mental Test Score (AMTS or Abbreviated Mental Test), Dementia questionnaire for persons with Mental Retardation (or DMR questionnaire), Cognitive Abilities Screening Instrument (CASI or Cognitive Abilities Screening Instrument), Trail-making test, Clock drawing test, Alzheimer's disease assessment scale - Cognition (ADAS-Cog or Cognitive Subscale of the Alzheimer's Disease Assessment Scale), General Practitioner Assessment of Cognition (GPCOG or assessment by a practitioner of cognition), Montreal Cognitive Assessment (MoCA or Montreal Cognitive Assessment), or Rowland Universal Dementia Assessment Scale (RUDAS or Rowland Dementia Assessment Scale). universal), or Alzheimer's Disease Cooperative Study - Activities of Daily Living (ADCS-ADL) according to their name in English.

More specifically, the MMSE is used to screen people with major neurocognitive impairment (dementia) without linking it to a particular pathology. The MMSE is also used to monitor people's cognitive status and to measure the decline in cognitive functions in people with neurocognitive impairment. This test assesses orientation, recording, attention and calculation, memory retention, language and construction praxis. CERAD (in its English name Consortium to Establish a Registry for Alzheimer's Disease) has established a dementia severity scale associated with the scores obtained in the MMSE. A score between 19 and 24 is associated with mild dementia, between 10 and 18 with moderate dementia, and a score below 10 corresponds to severe dementia, with a maximum score of 30. A change of 2 points in the score is generally considered clinically relevant.

The ADAS-Cog is a cognitive subscale of the Alzheimer's Disease Assessment Scale and therefore only addresses the cognitive aspects of dementia. Thus, it can be used to assess ( i.e. score) and monitor the progression of any type of dementia. The ADAS-Cog assesses orientation, memory, executive function, visuospatial ability, language or practice, with a score range of 0 to 70, with a higher score indicating greater impairment. The ADAS-Cog is considered more sensitive than the MMSE. It is one of the most commonly used tests for the clinical evaluation of candidate compounds for Marketing Authorization in the context of anti-dementia treatments and also for measuring the progression of cognitive impairment.

Thus a combination with a beneficial effect of the combination on the subject's cognitive abilities will show a slowing down, or a stabilization of the deterioration of the subject's cognitive abilities with regard to the usual evolution established in untreated subjects at the same stage of the disease for a given period of time. In other words, for example, in the case of the ADAS-Cog, a beneficial effect on the subject's cognitive abilities will correspond to a decrease, stabilization or increase of lower intensity in the ADAS-Cog score compared to the usual worsening of the score observed in untreated subjects at an equivalent stage and of an equivalent age. Although the worsening of the score depends on the stage of the pathology and the age of the subject, an annual increase of 5.82 points in the ADAS-Cog score is generally observed in subjects suffering from untreated Alzheimer's disease (Zhang et al. , 2020). For example, regarding the MMSE, a beneficial effect on the subject's cognitive abilities will correspond to an increase, a stabilization or a decrease of lower intensity of the MMSE score compared to the usual worsening of the MMSE score observed in untreated subjects. An annual decrease of 2.28 points in the MMSE score is generally observed in subjects suffering from untreated Alzheimer's disease (Rossetti et al . 2010).

Also, the study of evoked potential recordings (ERP for Event-Related Potential in English) is of great application in the evaluation of cognitive processes because the results are independent of the stimulus used. ERPs are observed in response to a discordant stimulus and represent activated cognitive phenomena such as perception, attention, decision-making process, memory process, language, etc. ERPs are recorded, for example, by electroencephalography (EEG) or magnetoencephalography (MEG). ERPs provide information on the processing of the stimulus by the brain even when no change in behavior is perceptible. The characteristics of the ERP can vary depending on various factors such as the relevance of the stimulus, the task performed, nervous system damage or medication intake.

ERPs are known in the state of the art as useful cognitive biomarkers for the diagnosis of dementia, monitoring of disease progression and assessing the pro-cognitive effect of treatments. For example, ERPs are altered in patients suffering from Alzheimer's disease, vascular dementia or dementia associated with parkinsonian symptoms, such as dementia with Lewy bodies. More specifically, ERP measurements allow the detection of cognitive impairment at an early stage and in particular in the case of early or mild Alzheimer's disease. The most frequently examined ERP in clinical practice is the P300 (or P3) wave which is a large centroparietal positivity that occurs with a latency of approximately 300 ms after the discordant stimulus. The P300 wave can be divided into two subcomponents P3a and P3b. P3a is generally considered to be related to the degree of focal attention, while P3b is thought to index the updating of working memory. The amplitude of the P300 wave refers in particular to motivation (related to the difficulty of the task) and to vigilance according to the probability of occurrence of the stimulus. Latency refers to the time required for decision-making. An increase in the latency of P300 (or its subcomponents) and a decrease in its amplitude (or its subcomponents) are observed in patients with dementia, particularly Alzheimer's disease. The study of the evolution of latency is useful for monitoring the progression of dementia, particularly Alzheimer's disease and for assessing the response to treatment of Alzheimer's disease.

Thus, the study of ERPs can make it possible to monitor the evolution of cognitive symptoms and thus to control the neuroprotection conferred by the combination of the invention. An increase in the latency in the occurrence of the P300 wave and/or a decrease in its amplitude is indicative of a degradation of the cognitive abilities of the individual tested. Thus, a decrease in the latency of the P300 wave and/or an increase in its amplitude will be a sign of neuroprotection.

The in vivo efficacy of a synergistic combination according to the invention can therefore easily be evaluated by any of the above-mentioned tests.

Composition according to the invention comprising a synergistic combination of FENM and at least one agonist of a sigma-1 receptor.

In another aspect, the invention relates to a composition comprising a synergistic combination as described above. More particularly, according to this aspect, the invention relates to a pharmaceutical composition comprising, or capable of reconstituting in the organism of the subject to whom it is administered, the synergistic combination according to the invention as described above.

In this composition, FENM or any of its pharmaceutically acceptable salts and the at least one agonist or positive modulator of a sigma-1 receptor or any of its pharmaceutically acceptable salts are formulated together or separately, in quantities and with excipients capable of reproducing the effects of said synergistic combination in the targeted organism.

In a particular embodiment, FENM and the at least one positive agonist or modulator of a sigma-1 receptor are the only active ingredients of said composition. In other words, FENM and the at least one positive agonist or modulator of a sigma-1 receptor are the only compounds within the composition having a therapeutic or preventive activity.

In another particular embodiment, the composition according to the invention comprises other active ingredients. Without an even more particular embodiment, these other active ingredients are selected from the compounds listed in Table 3 below.

Compound CAS Reference Number ^† donepezil 120014-06-4; 120011-70-3 galantamine 357-70-0; 1953-04-4; 5072-47-9 rivastigmine 123441-03-2 ; 129101-54-8 tacrine 321-64-2; 1684-40-8; 7149-50-0 memantine 19982-08-2; 41100-52-1

^† Chemical Abstracts Service database registration number.

A preferred donepezil salt is donepezil hydrochloride.

A preferred galantamine salt is galantamine hydrobromide.

A preferred rivastigmine salt is rivastigmine tartrate.

These molecules are known as symptomatic treatments, with sometimes limited effects, for certain degenerative pathologies. The use of some of these molecules is further limited by their adverse effects, or even their toxicity. Their combination with the synergistic combination of the invention can make it possible to increase their efficacy and/or avoid or reduce the adverse effects or toxicity by making it possible to reduce the doses. Thus, in another particular embodiment, the composition according to the invention further comprises, as active ingredient, at least one compound selected from donepezil, galantamine, rivastigmine and tacrine, or one of their pharmaceutically acceptable salts or their mixture. Even more particularly, the composition according to the invention further comprises 10 mg of donepezil, 7.5 mg of donepezil, 5 mg of donepezil, or even 2.5 mg of donepezil. In another particular embodiment, the composition according to the invention further comprises 16 mg of galantamine, 8 mg of galantamine, 4 mg of galantamine, or even 2 mg of galantamine. In another particular embodiment, the composition according to the invention further comprises 3 mg of rivastigmine, 1.5 mg of rivastigmine, or even 1 mg of rivastigmine.

Preferably, the composition is administered to the subject in the form of a pharmaceutical preparation, for example, but not limited to, orally, topically (cutaneously, buccally, sublingually) or parenterally (subcutaneously, intramuscularly or intravenously). Oral administration being particularly preferred.

The amounts of the active ingredients in this composition, i.e. at least FENM and the at least one positive agonist or modulator of a sigma-1 receptor, are compatible with the doses as determined above for the synergistic combinations of the invention. In other words, when said composition is in the form of a unit dosage (in the form of a tablet, capsule, powder, emulsion, solution) said dosage comprises amounts of FENM or of the at least one positive agonist or modulator of a sigma-1 receptor which are a multiple or a divisor of the doses determined for the synergistic combinations of the invention, thus making it possible to obtain in one or more doses the adequate dosage as defined above. In a particular embodiment, the composition according to the invention comprises 10 mg of igmesin, 9 mg of igmesin, 8 mg of igmesin, 7 mg of igmesin, 6 mg of igmesin, 5 mg of igmesin, 4 mg of igmesin, 3 mg of igmesin, or even 2 mg of igmesin. In another particular embodiment, the composition according to the invention comprises 50 mg of PRE-084, 25 mg of PRE-084, 10 mg of PRE-084, or even 9 mg of PRE-084, 8 mg of PRE-084, 7 mg of PRE-084, 6 mg of PRE-084, 5 mg of PRE-084, 4 mg of PRE-084, 3 mg of PRE-084, or even 2 mg of PRE-084. In another particular embodiment, the composition according to the invention comprises 50 mg of cutamesin, 25 mg of cutamesin, 10 mg of cutamesin, or even 9 mg of cutamesin, 8 mg of cutamesin, 7 mg of cutamesin, 6 mg of cutamesin, 5 mg of cutamesin, 4 mg of cutamesin, 3 mg of cutamesin, or even 2 mg of cutamesin.

In a particular embodiment, the composition according to the invention comprises 80 mg of FENM, 40 mg of FENM, 20 mg of FENM, 15 mg of FENM, 10 mg of FENM, 5 mg of FENM, 5 mg of FENM, 4 mg of FENM, 3 mg of FENM, or even 2 mg of FENM.

In another embodiment, in the composition according to the invention, the agonist (or positive modulator) molar ratio of a sigma-1/FENM receptor is less than or equal to 7, less than or equal to 6, less than or equal to 5, less than or equal to 4, less than or equal to 3, preferably less than or equal to 2, said agonist (or positive modulator) molar ratio of a sigma-1/FENM receptor being greater than or equal to 0.5. In a particularly preferred manner, said agonist (or positive modulator) molar ratio of a sigma-1/FENM receptor is less than 2 and greater than or equal to 0.5. In another particular embodiment, said agonist of a sigma-1 receptor is igmesin, and the igmesin/FENM molar ratio is less than or equal to 7, less than or equal to 6, less than or equal to 5, less than or equal to 4, is less than or equal to 3, preferably less than or equal to 2. Said igmesin/FENM molar ratio being greater than or equal to 0.1. In a particularly preferred manner, said igmesin/FENM molar ratio is less than 2 and greater than or equal to 0.5. In another particular embodiment, said agonist of a sigma-1 receptor is igmesin, and the igmesin/FENM molar ratio is less than or equal to 7, less than or equal to 6, less than or equal to 5, less than or equal to 4, is less than or equal to 3, preferably less than or equal to 2, said igmesin/FENM molar ratio being greater than or equal to 0.5. In a particularly preferred manner, said igmesin/FENM molar ratio is less than 2 greater than or equal to 0.5. In another particular embodiment, said agonist of a sigma-1 receptor is PRE-084, and the molar ratio PRE-084/FENM is less than or equal to 7, less than or equal to 6, less than or equal to 5, less than or equal to 4, is less than or equal to 3, preferably less than or equal to 2. Said molar ratio PRE-084/FENM being greater than or equal to 0.1. In a particularly preferred manner, said molar ratio PRE-084/FENM is less than 2 and greater than or equal to 0.5. In another particular embodiment, said agonist of a sigma-1 receptor is cutamesin, and the molar ratio cutamesin/FENM is less than or equal to 7, less than or equal to 6, less than or equal to 5, less than or equal to 4, is less than or equal to 3, preferably less than or equal to 2. Said molar ratio cutamesin/FENM being greater than or equal to 0.1. Particularly preferably, said cutamesine/FENM molar ratio is less than 2 and greater than or equal to 0.5.

The dose may be administered in several doses spread out over the day, the number of doses per day making it possible to obtain the desired daily dose. Thus, in a particular embodiment, the doses in question may be administered in one to four daily doses, for example 1 time, for example 2 times, for example 3 times, or even 4 times.

In a preferred embodiment, in said composition, the combination of FENM or of at least one agonist or modulator of a sigma-1 receptor is packaged so as to provide the dose corresponding to a dose without requiring manipulation such as a volume measurement, weighing or dividing a tablet, which is particularly advantageous in subjects with cognitive impairment since this avoids any calculation or particular manipulation.

For example, FENM or at least one agonist or positive modulator of a sigma-1 receptor are formulated separately in the form of powder, micro-granules, granules or even separate tablets and then combined in a capsule to facilitate their intake.

The pharmaceutical compositions may be formulated according to conventional pharmaceutical practice (see, for example, Remington: The Science and Practice of Pharmacy (23rd ed.), ed. A Adeboye Adejare, 2020) and the PK/PD characteristics of the active ingredients. Typically, in the compositions according to the invention, FENM and/or said at least one positive agonist or modulator of a sigma-1 receptor is mixed with a pharmaceutically acceptable excipient.

In one embodiment, said composition is in the form of a tablet or pill. Said tablet or pill may be divisible into 1, 2, 3, or even 4 pieces so as to be able to provide the subject with the dose required for one intake using 1, 2 or 3 or even 4 pieces of said tablet. This is particularly advantageous, for example, in the case where the treatment requires a period of dose increase, to reach the targeted daily dose, the pieces being able to correspond to the increase levels, and the entire tablet or pill to the target dose of the treatment.

In one embodiment, in said composition, FENM and the at least one positive agonist or modulator of a sigma-1 receptor are mixed within the same tablet or pill with the same excipient(s). In a particular embodiment, FENM and the at least one positive agonist or modulator of a sigma-1 receptor are present in different compartments of said tablet or pill with excipients that are specific to them, and which are a function of their physicochemical properties or their pharmacokinetic properties.

In another embodiment, particularly interesting in the case of molecules with different PK/PD profiles, the FENM and the at least one positive agonist or modulator of a sigma-1 receptor are present separately within this tablet. Thus, in a particular embodiment, the FENM and the at least one positive agonist or modulator of a sigma-1 receptor are present in different compartments of said tablet or pill, for example one compound being located outside and the other compound inside said tablet or pill, which allows separate and time-shifted administration of these compounds.

In one embodiment of the composition according to the invention, the FENM or the at least one positive agonist or modulator of a sigma-1 receptor can be formulated to be released substantially immediately upon administration, at any time, or at a predetermined time period after administration, i.e., formulated so as to be released in a controlled manner in the body. Controlled release formulations include (i) formulations which create a substantially constant concentration of the compound or its active derivative in the body over an extended period of time; (ii) formulations which, after a predetermined lag time, create a substantially constant concentration of the compound or its active derivative in the body over an extended period of time; (iii) formulations which maintain the action of the compound or its active derivative for a predetermined period of time by maintaining a relatively constant and effective level of said compound or its active derivative in the body, further allowing a concomitant minimization of undesirable side effects associated with fluctuations in the plasma level of said compound or its active derivative; (iv) formulations which localize the action of the compound or its active derivative, for example, near or within the diseased tissue or organ, or in a specific body compartment; and (v) formulations which target the action of said compound or its active derivative by using carriers or chemical derivatives to deliver the drug to a particular target cell type.

In other words, depending on their PK/PD characteristics, the active ingredients of the composition according to the invention can be administered in different galenic forms, which allow an accelerated, slowed, or prolonged release of each of the active ingredients relative to each other so as to reach the maximum concentrations and/or relevant molar ratios in the target compartment at the same time.

Administration of compounds in the form of a controlled release formulation is particularly preferred in cases where the compound has (i) a narrow therapeutic index (i.e. the difference between the plasma concentration leading to adverse effects, side effects or toxic reactions, and the plasma concentration leading to a therapeutic effect is low; in general, the therapeutic index, RT, is defined as the ratio of the median lethal dose (LD50) to the median effective dose (ED50)); (ii) a narrow absorption window in the gastrointestinal tract; or (iii) a very short biological half-life such that frequent administrations are necessary to maintain the plasma level at an effective therapeutic level. Different strategies can be pursued in order to achieve a release with a release rate of the compound or its active derivative adapted to the metabolism of the drug in question. Controlled release can be achieved by appropriate selection of various formulation parameters and ingredients, including, for example, various types of controlled release compositions and coatings known to those skilled in the art. Thus, the compound is formulated with suitable excipients into a pharmaceutical composition which, upon administration, releases said compound in a controlled manner (single or multiple compositions of tablets or capsules, oily solutions, suspensions, emulsions, microcapsules, microspheres, nanoparticles, patches and liposomes).

In an even more particular embodiment, specific technical means such as reservoirs, pumps or transdermal patches (in other words a self-adhesive patch which dispenses a substance percutaneously) can contribute to the controlled release of at least FENM and/or at least one agonist or positive modulator of a sigma-1 receptor.

In another embodiment, said composition is formulated in liquid form. It can then be packaged in unit dose form in containers such as ampoules, or in a container such as a bottle or vial associated with a device allowing the withdrawal and, optionally, the administration of the desired volume to obtain the adequate dose.

Therapeutic uses of the synergistic combination or composition according to the invention.

The novel synergistic effect discovered by the inventors for the combination of FENM with at least one agonist or positive modulator of a sigma-1 receptor identified by the inventors constitutes a novel therapeutic solution.

Thus, according to another aspect, the invention relates particularly to the composition or synergistic combination as described above in all their embodiments, for their use as a medicament. Thus, the invention relates to a synergistic combination of FENM and at least one agonist or positive modulator of a sigma-1 receptor for its use as a medicament. Those skilled in the art easily know how to determine the agonist or positive modulation activity of the sigma-1 receptor of a compound by detecting, for example, the dissociation of the BiP/sigma-1 receptor complex in a cell line (Hayashi & Su, Cell, 2007) in response to the exposure of the cells to this compound. In a particular embodiment, the invention relates to a synergistic combination of FENM and igmesine, FENM and PRE-084, or FENM and cutamesine, or a composition comprising it, as described above in all their embodiments, for its use as a medicament.

In a further aspect, the invention particularly relates to the composition or synergistic combination, as described above, for their use in the treatment of a pathology selected from tauopathies, synucleinopathies, amyloidopathies, neurogenetic diseases of metabolic origin (e.g. GM2 ganliosidosis, Krabbe disease, Fabry disease, sialidosis type I, Gaucher disease, Niemann-Pick disease type C, Refsum disease, cerebrotendinous xanthomatosis, adrenoleukodystrophy), Alzheimer's disease, Parkinson's disease, multiple system atrophy, Huntington's disease, posterior cortical atrophy, Pick's disease, epilepsy, vascular dementia, frontotemporal dementia, dementia with Lewy bodies, lateral sclerosis amyotrophic. In a particular embodiment, said treatment relates to the treatment of Alzheimer's disease in its early, moderate or advanced stages, preferably Alzheimer's disease in its early stages. In a particular embodiment, said treatment relates to the treatment of cognitive disorders associated with any of the pathologies selected from a tauopathy, a synucleinopathy, an amyloidopathy, Alzheimer's disease, Parkinson's disease, multiple system atrophy, Huntington's disease, posterior cortical atrophy, Pick's disease, epilepsy, vascular dementia, frontotemporal dementia, dementia with Lewy bodies, amyotrophic lateral sclerosis.

A particular embodiment relates to the composition or synergistic combination as described above for their use in the treatment, prevention, reduction or slowing down of the progression of alterations in cognitive abilities in a subject suffering, suspected of suffering or considered at risk of suffering from a neurodegenerative pathology.

A particular embodiment relates to the synergistic composition or combination as described above for their use in the treatment of cognitive disorders associated with the early, moderate or advanced stage of Alzheimer's disease, preferably in the early stage. Indeed, the experimental data show a particularly important synergistic effect in the treatment of long-term contextual memory impairments, which presents a particular advantage in the case of patients in the early stage of the disease.

• de la mémoire à court terme,
• de la mémoire à moyen terme,
• de la mémoire spatiale, ou
• des capacités de reconnaissance et/ou d’apprentissage,

Another particular embodiment relates to the composition or synergistic combination as described above for their use in the treatment of alterations:

• short term memory,
• medium-term memory,
• spatial memory, or
• recognition and/or learning capabilities,

associated with any of the pathologies selected from a tauopathy, a synucleinopathy, an amyloidopathy, Alzheimer's disease, Parkinson's disease, multiple system atrophy, Huntington's disease, posterior cortical atrophy, Pick's disease, epilepsy, vascular dementia, frontotemporal dementia, dementia with Lewy bodies, amyotrophic lateral sclerosis. In a particular embodiment, said alterations of short-term memory, medium-term memory, spatial memory, or recognition and/or learning abilities are associated with the early, moderate or advanced stage of Alzheimer's disease, preferably the early stage.

In another aspect, the invention relates to a method of treating a pathology selected from tauopathies, synucleinopathies, amyloidopathies, neurogenetic diseases of metabolic origin (e.g., GM2 ganliosidosis, Krabbe disease, Fabry disease, sialidosis type I, Gaucher disease, Niemann-Pick disease type C, Refsum disease, cerebrotendinous xanthomatosis, adrenoleukodystrophy), synucleinopathies, amyloidopathies, Alzheimer's disease, Parkinson's disease, multiple system atrophy, Huntington's disease, posterior cortical atrophy, Pick's disease, epilepsy, vascular dementia, frontotemporal dementia, dementia with Lewy bodies, amyotrophic lateral sclerosis comprising the administration to a subject in need thereof of a synergistic combination of FENM or any of its pharmaceutically acceptable salts with at least one acetylcholinesterase inhibitor or any of its pharmaceutically acceptable salts.

In said method, said synergistic combination is as described above, in all its embodiments. In one embodiment, said method may comprise administering a composition according to the invention as described above.

In a particular embodiment, said method comprises the separate, concomitant or sequential administration of FENM and the at least one positive agonist or modulator of a sigma-1 receptor. In this embodiment, FENM and the at least one positive agonist or modulator of a sigma-1 receptor can be administered separately to the subject by identical routes, such as for example orally, parenterally or transdermally. In an alternative embodiment, FENM and the at least one positive agonist or modulator of a sigma-1 receptor can be administered to the subject by different routes. For example one orally and the other transdermally or parenterally.

[Examples]

Abbreviations

Aβ_25-35:fragment of 11 amino acids of sequence Nt-GSNKGAIIGLM-Ct (SEQ ID NO 1) of the APP peptide.

FENM: 3(2-Fluoroethyl)tricyclo[3.3.1.13,7]decan-1-amine hydrobromide (also fluoroethylnormemantine hydrobromide).

ICV: intracerebroventricular.

IP: intraperitoneal

IC: combination index.

iChE: acetylcholinesterase inhibitor

PP: percentage of protection.

CNS: Central Nervous System.

MA: Alzheimer's disease

1. Materials and methods

Animal experiments are conducted in accordance with the provisions of European Union Directive No. 2010/63 and have been duly authorized by the National Consultative Ethics Committee (CCNE) of the French Republic and the ARRIVE directives (Kilkenny et al ., 2010).

1.1. Animals

In vivo experiments were conducted on male Swiss OF-1 mice (Janvier, St Berthevin, France) aged 7 to 9 weeks with a mass of 32± 2 g. The animals were housed in groups of 8 to 10 individuals in plastic cages with ad libitum access to food and drink, in a controlled environment (12-h day/night cycle, lights coming on at 7:00 a.m. and behavioral experiments taking place between 9:00 a.m. and 5:00 p.m.), under a controlled atmosphere and sound environment.

1.2. Test compounds and peptides

Stock solutions of sigma-1 agonists and FENM

PRE-084 hydrochloride and cutamesine were obtained from Sigma-Aldrich (Saint-Quentin-Fallavier, France). Igmesine hydrochloride was obtained from Pfizer (France). FENM was provided by M2i Life Sciences (Saint-Cloud, France). Stock solutions of the compounds were obtained by solubilization in NaCl buffer (0.9%, vehicle) at a concentration of 1 mg/mL, which corresponds to a dose of 5 mg/kg. These stock solutions were stored at 4°C for up to 2 weeks. The solutions were administered by intraperitoneal (IP) injection in a volume of 100 µl per 20 g of body weight.

Amyloid peptide stock solution [25-35]; formation of oligomers

The amyloid peptide [25-35], denoted Aβ _25-35 (Genepep, Saint-jean-de-Vedas, FRANCE), was solubilized in sterile distilled water at a concentration of 3 mg/mL, the stock solution thus formed is aliquoted and stored at -20°C until use.

Aβ _25-35 oligomers are formed as described by Maurice et al. (1996), during incubation at 37°C for 4 days before injection into animals. The vehicle solution or the control peptide are subjected to the same treatment before administration. It has already been shown that injection of vehicle solution (distilled water) gives the same lack of effect as injection of control peptide Sc Aβ (control peptide), which comprises the same amino acids as Aβ _25-35 in a random order and which does not oligomerize.

Administration to animals

The compounds are administered IP in a volume of 100 µL per 20 g of body weight. The administration of FENM/sigma-1 receptor agonist combinations is carried out in a volume of 100 µL per 20 g of body weight. The doses of compounds mentioned in the experimental part correspond to the doses of the salts of the compounds used and not to the mass equivalent of the compound itself. The doses administered expressed in moles are mentioned in Table 4. For each compound the doses administered are 0.03; 0.1 and 0.3 mg/kg.

The corresponding doses expressed in mMol/Kg are reported in table 4 below.

Active ingredient Dose in mg/kg in the experiments Dose in mmol/kg fluoroethylnormemantine 0.01 0.04 0.03 0.11 0.1 0.36 PRE-084 0.03 0.09 0.1 0.28 0.3 0.85 igmesine 0.03 0.08 0.1 0.28 0.3 0.84 cutamesin 0.03 0.07 0.1 0.25 0.3 0.74

The Aβ _25-35 oligomer solution, the vehicle (sterile distilled water) are administered to the mice by ICV injection, as described in Maurice et al. (1996).

1.3. Cognitive/behavioral tests

The ICV injection model of Aβ _25-35 oligomers is a well-known model in the state of the art (Maurice et al., 1996). This model is considered a relevant model for screening the neuroprotective activity of compounds, and more particularly a relevant first-line model of Alzheimer's disease. Aβ _25-35 oligomers are known to be cytotoxic to neuronal cells in mice and induce memory disorders. This deficit is accompanied by the generation of mitochondrial stress, oxidative stress and apoptosis of cells, particularly in the hippocampus, and by inflammation of the central nervous system.

The ability of the compounds and their combination to decrease cognitive symptoms of Aβ _25-35 oligomer-induced neurodegeneration is tested. For this, the administration of the test compounds takes place on the same day as the injection of the Aβ _25-35 oligomers and continues on a daily basis until day 7 after the injection of the Aβ _25-35 oligomers; the mice are then subjected to the spontaneous alternation tests, or passive avoidance tests on day 8 after the injection of the Aβ _25-35 oligomers.

Passive Avoidance Test

This test measures long-term non-spatial (contextual) memory. The apparatus used for this test is a two-compartment box (15 x 20 x 15 cm high) one illuminated with white PVC walls and the other darkened with black PVC walls and a grid floor. A guillotine door separates the compartments. A 60 W lamp is positioned 40 cm above the box and illuminates the white compartment. Electric shocks (0.3 mA for 3 s) can be applied to the grid floor via a generator (Lafayette Instruments, Lafayette, USA). The test consists of a training session and a test session. The guillotine door is closed during the training session. Each mouse is placed in the white compartment. After 5 s, the door is raised. When the mouse enters the dark compartment so that all four paws are in contact with the mesh, the door is closed and electric shocks are applied for 3 seconds. The time taken by the mouse to enter the dark compartment (passage latency) and the level of shock sensitivity (0 = no sign; 1 = startles; startles and vocalizations) are recorded. The recall session is carried out 24 hours after the training session. Each mouse is placed back in the illuminated white compartment. After 5 seconds, the door is raised, the passage latency, i.e. the time taken by the mouse to go to the dark compartment is measured. The maximum duration is 300 seconds. Mice with latencies during learning and recall < 10 s and a low level of shock sensitivity are not considered for the test. The attrition rate is usually 5%. A mouse with impaired memory abilities will have a significantly lower recall latency than a mouse with normal abilities. Results are presented as their median value with interquartiles (25%-75%).

Spontaneous alternation test in the Y-maze

The spontaneous alternation test is used to study spatial working (very short-term) memory in rodents. The maze is made of gray opaque polyvinyl chloride (PVC). Each of its arms is 40 cm long, 13 cm high and 3 cm wide at its base, 10 cm at its top. The arms converge towards each other, with an equal angle between the different arms. Briefly, each mouse is placed at the end of an arm and is left free to move for an 8-min session. The mouse's entries into each of the arms, including the arm at the end of which it was placed, are recorded. An alternation is defined as the animal successively entering three different arms. The maximum number of alternations is therefore the total number of entries into each of the arms minus 2 and the alternation percentage is calculated according to the formula:

Data from animals showing extreme behaviors (alternation percentage < 20% or > 90%) are not included in the calculations. The attrition rate is usually 5%. Under normal conditions, a mouse will spontaneously alternate explorations of each arm. A mouse with impaired memory and/or orientation abilities will see its alternation percentage decrease.

1.4. Statistical analyses

Analyses were performed using Prism v9.0 (GraphPad Software, San Diego, CA, USA). Data were analyzed using one-way analyses of variance (ANOVA, F value) followed by Dunnett's test or nonparametric Kruskal-Wallis ANOVA (H value) followed by Dunn's comparison test. Statistical significance levels were p < 0.05, p < 0.01, and p < 0.001.

1.5. Calculation of the combination index (CI)

The nature of the interaction of two compounds at a given effect level was assessed by isobologram analysis (Martin et al ., 2020; Maurice, 2016). The representation of isobolograms follows the concept of Fraser (1872). The dose-response curves follow a biphasic effect, only the ascending part of the curve was considered in the calculations. The concentration required to produce a given effect (e.g., where ICx = IC50) is determined for compound A (ICx,A) and compound B (ICx,B) and indicated on the x and y axes of a two-coordinate plot, forming the two points, (ICx,A, 0) and (0, ICx,B). The line connecting these two points is the additivity line. In a mixture of drugs A + B, the concentrations of A and B contained in the combination that produce the same effect are represented by the coordinates (CA,x, CB,x).

The combination index (CI) is calculated as follows:

where CA,x and CB,x are the concentrations of compounds A and B used in a combination that generates x% of the maximum combination effect.

IC is the combined index. ICx,A and ICx,B are the concentrations of compounds A and B required alone to produce x% of the maximal effect. An IC less than/equal to/greater than 1 indicates synergy/additivity/antagonism, respectively. To calculate the IC based on isobologram representation, alternation percentages and passive avoidance latencies were expressed as percent protection (PP) for each treatment group with PP(V/V) set to 100% and PP(Aβ ₂₅ - ₃₅ /V) set to 0% (Martin et al ., 2020; Maurice, 2016).

2. Results

2.1. Synergistic effect of a FENM-PRE-084 combination on working memory and long-term memory, in a pharmacological model of AD

The data confirm the anti-amnesic effects of FENM and PRE-084 on Aβ _25-35 oligomer-induced impairments in short-term working memory and long-term memory.

Chemical formula of PRE-084

First, sub-effective doses were investigated, i.e. doses of compounds at which, when administered alone, an effect on FENM-induced damage at the limit of significance is observed or doses immediately lower than the first significantly active dose, then the combinatorial treatment was administered and the presence of synergy of the memory effects of the two molecules was observed.

In the spontaneous alternation test, improved performance of Aβ-treated mice_25-35And administered with FENM alone is observed from 0.03 mg/kg ( A), since these performances are not significantly different from those of untreated mice. Mice treated with 0.3 mg/kg FENM perform significantly better in this test than mice administered with (Aβ_25-35+V). Administration of PRE-084 alone also allows an improvement in the memory capacities of the animals measured by this test which are significantly different from those of mice administered with 0.1 and 0.3 mg/kg. However, no improvement is observed at 0.03 mg/kg.

In the passive avoidance test, improved performance of Aβ-intoxicated mice_25-35And administered with FENM alone is observed at 0.3 mg/kg ( A), since these performances are significantly different from those of the intoxicated mice, nevertheless the observed performances remain significantly different from those of the mice treated with (V+V). Similar results are observed in this test for PRE-084 ( HAS).

The minimum active doses for each of the molecules 0.01 and 0.03 mg/kg for FENM and 0.03 and 0.1 mg/kg for PRE-084, were tested in combination for each of the behavioral tests. The percentage of protection was calculated from the experimental data ( B, B) and the CI was determined from linear regressions and isobologram analysis, for each combination (Table 5). CIs less than 1 are observed for all combinations tested for both types of memory evaluated ( and 2). A synergy of action with a CI particularly lower than 1 is identified for the FENM/PRE-084 combination at doses of 0.01 and 0.03 for FENM and 0.03 for PRE-084 (Table 5 and B, B) and whether for the restoration of short- or long-term memory.

The combination index data for these experiments are reported in Table 5 below.

The observed CIs indicate a strong synergistic interaction between FENM and PRE-084, as illustrated by the percentage protection scale ( B, B). This strong synergistic interaction results in an improvement in the memory performance of animals treated with Aβ _25-35 and with the FENM+PRE-084 combination illustrated by a percentage of protection not reached for mice when administered with the molecules alone, whatever the doses.

2.2. Synergistic effect of a FENM-igmesine combination on short- and long-term working memory in an Aβ model _25-35

The experiments and data analysis are carried out in the same manner as before.

Chemical formula of igmesine

At the doses tested, igmesine was found to be effective in protecting short-term memory ( A) and less effective in protecting long-term working memory ( A). FENM, in these experiments, produced significant protective effects on short-term memory from doses of 0.03 and 0.1 mg/kg, but little improvement on long-term working memory, as previously observed.

The percentage of protection was calculated from the experimental data ( B, B) and the CI was determined from linear regressions and isobologram analysis, for each combination (Table 6). A synergy of action is identified for the FENM+igmesine combination at the low doses tested (Table 6 and ( B, B)) and whether for the restoration of short- or long-term memory.

A synergy of action is identified for the FENM+igmesine combination (Table 6 and ( B, B) whether for the restoration of short- and long-term memory.

2.3. Synergistic effect of a FENM-cutamesin combination on short- and long-term working memory in an Aβ model _25-35 .

The experiments and data analyses are carried out in the same manner as in 2.1.

Cutamesin formula

Cutamesine was found to be active at the doses tested in protecting both types of memory against memory impairment induced by the administration of Aβ _25-35 ( A and A). The results observed for FENM are similar to those observed in 2.2. on working memory.

The percentage of protection was calculated from the experimental data ( B, B) and the CI was determined from linear regressions and isobologram analysis, for each combination (Table 7). A synergy of action is identified for the FENM+cutamesine combination for all doses tested (Table 7 and ( B)) for the restoration of short-term memory.

3. Conclusions

These data show a synergy of the protective effects of FENM combined with those of sigma-1 receptor agonists, of very different chemical structures, for both short-term and long-term working memory.

These results allow to consider the use of combinations of FENM with at least one agonist or positive modulator of a sigma-1 receptor in patients currently without an approved therapeutic solution for the treatment of memory symptoms of AD or related pathologies. Also, the observed synergy which allows to obtain a therapeutic effect at particularly low doses of the compounds at which few or no adverse effects are expected.

Claims (9)

Synergistic combination of 3-(2-fluoroethyl)adamantan-1-amine (FENM) or any of its pharmaceutically acceptable salts and at least one agonist or positive modulator of a sigma-1 receptor or any of its pharmaceutically acceptable salts. The synergistic combination according to claim 1 wherein said at least one positive agonist or modulator of a sigma-1 receptor is selected from 2-(2-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3,5-Dichlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(2,3-Dichlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Fluorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-Fluorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Nitrophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4 benzyloxycarbamoylphenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(Pyridin-2-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyridin-3-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyridin-4-yl)-2-oxo-3,3,5,5-tetramethyl[1,4,2]-oxazaphosphinane; 2-(Pyrimidin-2-yl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(Pyrimidin-5-yl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-aminophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(4-aminophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-chlorophenyl)-N-methyl-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-chlorophenyl)-2-thiono-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane; 2-(3-Chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane, PRE-084 (2-morpholin-4-ylethyl 1-phenylcyclohexane-1-carboxylate), (+)-pentazocine, (+)-SKF10,047, cutamesine, fluvoxamine, igmesine, OPC-14523, BD737, BHDP, pridopidine, ANAVEX1-41, ANAVEX2-73, ANAVEX3-71, SDHEA, selegiline, fluoxetine, citalopram, amitriptyline, L-687384, dipentylamine, dextromethorphan, dimethyltryptamine, opipramol or a pharmaceutically acceptable salt thereof. The synergistic combination according to any one of claims 1 to 2, wherein said at least one agonist of a sigma-1 receptor is selected from PRE-084 (2-morpholin-4-ylethyl 1-phenylcyclohexane-1-carboxylate), cutamesine (1-[2-(3,4-dimethoxyphenyl)ethyl]-4-(3-phenylpropyl)piperazine) and igmesine ((5E)-N-(cyclopropylmethyl)-N-methyl-3,6-diphenyl-5-hexen-3-amine). The synergistic combination according to any one of claims 1 to 3, wherein said at least one positive modulator of a sigma-1 receptor is 2-(3-chlorophenyl)-2-oxo-3,3,5,5-tetramethyl-[1,4,2]-oxazaphosphinane or a pharmaceutically acceptable salt thereof. The synergistic combination according to any one of claims 1 to 4, wherein the molar ratio of agonist or positive modulator of a sigma-1 receptor/FENM is less than or equal to 7, said molar ratio being greater than or equal to 0.5. The synergistic combination according to any one of claims 1 to 5 for use as a medicament. The synergistic combination according to any one of claims 1 to 6 for its use in the treatment of a pathology selected from neurogenetic diseases of metabolic origin, tauopathies, synucleinopathies, amyloidopathies, Alzheimer's disease, Parkinson's disease, multiple system atrophy, Huntington's disease, posterior cortical atrophy, Pick's disease, epilepsy, vascular dementia, frontotemporal dementia, dementia with Lewy bodies, amyotrophic lateral sclerosis, GM2 ganliosidosis, Krabbe's disease, Fabry's disease, sialidosis type I, Gaucher's disease, Niemann-Pick disease type C, Refsum's disease, cerebrotendinous xanthomatosis, adrenoleukodystrophy. The synergistic combination according to any one of claims 1 to 7 for its use in the treatment, prevention, reduction or slowing down of the development of alterations in cognitive abilities in a subject suffering, suspected of suffering or considered at risk of suffering from a neurodegenerative pathology. A pharmaceutical composition comprising the synergistic combination according to one of claims 1 to 8.