WO2023241799A1

WO2023241799A1 - Flavanols for use in the treatment of retroviral infections

Info

Publication number: WO2023241799A1
Application number: PCT/EP2022/066424
Authority: WO
Inventors: Paul Niebes; Carine Van Lint; Maryam BENDOUMOU
Original assignee: Université Libre de Bruxelles
Priority date: 2022-06-15
Filing date: 2022-06-15
Publication date: 2023-12-21

Abstract

Aspects of the invention concern the use of monomeric flavanol- type compounds, such as (+)-catechin, (-)-catechin, (-F)-epicatechin, (-)-epicatechin, (-F)-epicatechin gallate, (-)-epicatechin gallate, (+) -gallocatechin, (-)-gallocatechin, (-F)-gallocatechin gallate and (-) -gallocatechin gallate, or stereoisomers, or prodrugs thereof, in a methods of treating retroviral infections.

Description

FLAVANOLS FOR USE IN THE TREATMENT OF RETROVIRAL INFECTIONS

FIELD

The present invention lies in the medical field, particularly in the field of treatments for infectious diseases, more particularly retroviral infections, such as Human Immunodeficiency Virus (HIV) infections.

BACKGROUND

Combination antiretroviral therapy (cART) is currently the only therapeutic option available for HIV-1 infected individuals. If cART is efficient in suppressing viral replication and in prolonging the lifespan of infected individuals, the persistence of transcriptionally-silent proviruses, particularly in latently-infected resting memory CD4+ T cells, still prevents HIV-1 eradication. Therefore, these latent reservoirs are a permanent source for virus reactivation and could be responsible for the rebound of plasma viral load observed after cART interruption. Consequently, cART treatment requires lifelong adherence, leading to several long term side effects and a life expectancy lower than that of uninfected individuals. As such, much effort has been put into understanding the multiple molecular factors involved in viral latency to develop new anti- HIV therapeutic strategies. One such strategy relies on the use of latency-reversing agents (LRAs) that target repressors of HIV-1 gene expression, thereby inducing a controlled activation of the latent reservoirs of the virus.

The multifactorial process of HIV-1 silencing during latency is controlled, in part, by several interrelated epigenetic mechanisms that collectively govern the chromatin architecture of the provirus. In particular, the latent HIV-1 promoter, located within the 5’Long Terminal Region (5’LTR), is maintained in a tight heterochromatic state by the concurrent recruitment of multiple cellular epigenetic machineries. In addition to the precise nucleosome positioning, as well as the accumulation of specific inhibitory histone modifications, the HIV-1 promoter contains two CpG islands (CGIs) surrounding the transcriptional start site. Both CGIs have been reported to be hypermethylated in latently-infected T-cell line models, thus participating in the 5’LTR heterochromatinization during latency. Methylation of the HIV-1 promoter in patient cells has been reported in some studies but other reports denied the implication of 5’LTR methylation ex vivo. Explaining these apparently contradictory results, recent studies demonstrated that clinical characteristics of HIV+ individuals, such as duration of the infection or duration of the antiretroviral treatment, influence the accumulation of DNA methylation on the 5’LTR. In this regard, a recently study reported a progressive longitudinal accumulation of proviruses integrated in DNA regions with hypermethylated cytosine residues upstream of the proviral 5’LTR promoter, suggesting a role of DNA methylation in silencing proviral transcriptional activity during prolonged anti-retroviral therapy. In addition, several latency factors have been proposed for the recruitment of the cellular DNA methyltransferases (DNMTs) at the HIV-1 promoter, indicating an additional heterogeneity in the mechanisms responsible for the accumulation of DNA methylation on the viral promoter. In agreement, we have previously shown that latency reversal with the DNA methylation inhibitor 5 -AZA-2’ -deoxy cytidine (5-AzadC or decitabine) is associated with patientspecific qualitative and quantitative variations in HIV-1 reactivation from latency (Bouchat et al. 2016. EMBO Mol Med., vol. 8, 117-138).

SUMMARY

The present invention is at least in part based on the inventors’ discovery that monomeric flavanoltype compounds display retrovirus latency reversal activity and can therefore be useful in the treatment of retroviral infections.

Accordingly, an aspect of the invention provides a monomeric flavanol-type compound, or a stereoisomer, or prodrug thereof, for use in a method of treating a retroviral infection.

A further aspect provides a pharmaceutical composition comprising at least one monomeric flavanol-type compound or a stereoisomer, or prodrug thereof, for use in a method of treating a retroviral infection.

Another aspect provides a method for treating a retroviral infection in a subject in need of such treatment, comprising administering to said subject a therapeutically or prophylactically effective amount of a monomeric flavanol-type compound, or a stereoisomer, or prodrug thereof, or a pharmaceutical composition comprising at least one monomeric flavanol-type compound or a stereoisomer, or prodrug thereof.

The above and further aspects and preferred embodiments of the invention are described in the following sections and in the appended claims. The subject-matter of appended claims is hereby specifically incorporated in this specification.

BRIEF DESCRIPTION OF DRAWINGS

The following description of the figures of specific embodiments of the invention is merely illustrative in nature and is not intended to limit the present teachings, their application or uses.

Figure 1 demonstrates that EGCG or by (+)-catechin promote HIV-1 reactivation from latency. The HIV-1 latently infected T-cell line J-Lat 6.3 was mock-treated or treated with increasing doses of epigallocatechin-3 -gallate (EGCG, Sigma #E4143) or (+)-catechin for 24 hours. Following this, HIV-1 reactivation from latency was assessed by flow cytometry (panel A). J-Lat cell lines harbour a full-length latent HIV-1 provirus with the gene encoding the eGFP in place of nef. The transcriptional state of the HIV-1 promoter can thus be detected in individual cells by flow cytometry. Cellular proliferation was evaluated by the colorimetric test WST-1 according to the manufacturer’s instructions (Roche) (panel B). The Cell Proliferation Reagent WST-1, based on its cleavage to a soluble formazan depending on the glycolytic production of NAD(P)H in viable cells, was used for the spectrophotometric quantification of cell proliferation and viability in cell populations. Therefore, the amount of formazan dye formed directly correlates with the number of metabolically active cells in the culture.

DESCRIPTION OF EMBODIMENTS

Before describing the present invention in greater detail, it should be understood that this invention is not limited to the particular processes, compositions, uses, components, products or combinations described, these compositions, uses, processes, components, products or combinations possibly of course varying. It is also understood that the terminology used herein could not be considered to be restricted, given that the field of application of the present invention will have as limit only the attached claims.

As used herein, the singular forms “a”, “an” and “the” include the singular and plural references except if the context clearly indicates the contrary.

The terms “comprising”, “comprises” and “composed of’ as used herein are synonyms of “including”, “includes”, “containing” or “contains”, and are inclusive or open and do not exclude the additional members, elements or process steps not mentioned. It should not be forgotten that the terms “comprising”, “comprises” and “composed of’ as used herein comprise the terms “constituted of’, “consists in” and “consists of’, and also the terms “essentially consisting of’, “essentially consisting in” and “essentially consists of’.

The mention of numerical value ranges by their extreme points includes all the numbers and fractions integrated into the respective ranges, and also the extreme points recited.

The term “about” or “approximately” as used herein, when applied to a measurable value such as a parameter, an amount, a time period, and others that are similar, means that there is a degree of variation of ± 20% or less, preferably of ± 10% or less, more preferentially of ± 5% or less, and even more preferentially of ± 1% or less relative to the value specified, insofar as these variations are appropriate for implementing the present invention. It is understood that the value to which the description “about” or “approximately” refers is itself also specifically and preferably described.

Although the terms “one or more” or “at least one”, such as one or more or at least one member(s) of a group of members, is clear as such, by means of a demonstration by example, the term includes, inter alia, a reference to any one of said members, or to at least any two of said members, for instance > 3, > 4, > 5, > 6 or > 7, etc., of said members, and up to all said members.

All the references cited in the present description are incorporated herein by way of reference in their entirety. In particular, the teachings of all the references expressly mentioned herein are incorporated by way of reference.

As used herein, the term “and/or” when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a list is described as comprising group A, B, and/or C, the list can comprise A alone; B alone; C alone; A and B in combination; A and C in combination, B and C in combination; or A, B, and C in combination.

The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g., 1 to 5 can include 1, 2, 3, 4 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of end points also includes the end point values themselves (e.g., from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all sub-ranges subsumed therein.

Unless they are defined otherwise, all the terms used in the description of the invention, including the technical and scientific terms, have the meaning commonly understood by any person skilled in the art of which the invention is part. As additional information, definitions of the terms are included for better understanding of the teaching of the present invention.

In the following paragraphs, various aspects of the invention are defined in greater detail. Each aspect thus defined can be combined with any one or other aspects unless clearly indicated otherwise. In particular, any feature indicated as being preferred or advantageous can be combined with one or other features indicated as being preferred or advantageous.

Any reference in this description to “one embodiment” means that a particular function, structure or feature described relative to the embodiment is included in at least one embodiment of the present invention. Thus, the occurrences of the phrase “in one embodiment” in various places in this description do not all necessarily refer to the same embodiment, but may do so. Moreover, the particular functions, structures or features can be combined in any appropriate manner, as would appear obvious to those skilled in the art on reading this description, in one or more embodiments. Moreover, although some embodiments described herein comprise some but not other features included in other embodiments, the combinations of features of the various embodiments are in the field of application of the invention, and form various embodiments, as will be understood by those skilled in the art. For example, in the attached claims, any one of the claimed embodiments can be used in any combination.

Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects.

Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, definitions for the terms used in the description are included to better appreciate the teaching of the present invention.

The present inventors have demonstrated that monomeric flavanol-type compounds can reactivate retroviruses from latency and can therefore be useful in methods of treating retroviral infections. For example, by reactivating the latent virus, the virus and/or the virus-infected cells can thereafter be cleared by the action of the immune system, or can be better managed by antiretroviral therapies, such as established combination antiretroviral therapy (cART).

Accordingly, in an aspect the invention relates to a monomeric flavanol-type compound, or a stereoisomer, or prodrug thereof, for use in a method of treating a retroviral infection.

A further aspect relates to a pharmaceutical composition comprising at least one monomeric flavanol-type compound or a stereoisomer, or prodrug thereof, for use in a method of treating a retroviral infection.

The term “monomeric flavanol-type compound”, “flavanols”, “3 -flavanols”, “flavan-3-ols” or “catechins” refer to a group of single-molecule compounds that possess a 2-phenyl-3,4-dihydro- 2H-chromen-3-ol skeleton and constitute a subfamily of flavonoids which are secondary metabolites of plants all sharing the same basic scaffold formed by two aromatic rings connected by three carbons: G.-CAG,. This term also encompasses derivatives of flavanol compounds, wherein one or more of the OH functions is derivatized, for example by alkoxylation or by acylation, for example tetramethoxy catechin, pentaacetoxycatechin, and cyclic derivatives. The term “isomers” as used herein means all possible isomeric forms, including tautomeric and stereochemical forms, which the compounds of the invention may possess, but not including position isomers. Typically, the structures shown herein exemplify only one tautomeric or resonance form of the compounds, but the corresponding alternative configurations are contemplated as well. Unless otherwise stated, the chemical designation of compounds denotes the mixture of all possible stereochemically isomeric forms, said mixtures containing all diastereomers and enantiomers (since the compounds of formulae herein may have at least one chiral centre) of the basic molecular structure, as well as the stereochemically pure or enriched compounds. More particularly, stereogenic centres may have either the R- or S -configuration, and multiple bonds may have either cis- or trans-configuration.

Pure isomeric forms of the said compounds are defined as isomers substantially free of other enantiomeric or diastereomeric forms of the same basic molecular structure. In particular, the term “stereoisomerically pure” or “chirally pure” relates to compounds having a stereoisomeric excess of at least about 80% (i.e., at least 90% of one isomer and at most 10% of the other possible isomers), preferably at least 90%, more preferably at least 94% and most preferably at least 97%. The terms “enantiomerically pure” and “diastereomerically pure” should be understood in a similar way, having regard to the enantiomeric excess, respectively the diastereomeric excess, of the mixture in question. Separation of stereoisomers is accomplished by standard methods known to those in the art.

As used herein and unless otherwise stated, the term “enantiomer” means each individual optically active form of a compound of the invention, having an optical purity or enantiomeric excess (as determined by methods standard in the art) of at least 80% (i.e., at least 90% of one enantiomer and at most 10% of the other enantiomer), preferably at least 90% and more preferably at least 98%.

The term “pro-drug” or “prodrug” as used herein means the pharmacologically acceptable derivatives such as esters, amides and phosphates, such that the resulting in vivo biotransformation product of the derivative is the active drug. The reference by Goodman and Gilman (The Pharmacological Basis of Therapeutics, 8th Ed, McGraw-Hill, Int. Ed. 1992, “Biotransformation of Drugs”, p 13-15) describing pro-drugs generally is hereby incorporated. Pro-drugs of the compounds of the invention can be prepared by modifying functional groups present in said component in such a way that the modifications are cleaved, either in routine manipulation or in vivo, to the parent component. Typical examples of pro-drugs are described for instance in WO 99/33795, WO 99/33815, WO 99/33793 and WO 99/33792 all incorporated herein by reference. Pro-drugs are characterized by increased bio-availability and are readily metabolized into the active inhibitors in vivo. The term “pre-drug” as used herein is synonymous with the above terms, and means any compound that will be modified to form a drug species, wherein the modification may take place either inside or outside of the body, and either before or after the pre-drug reaches the area of the body where administration of the drug is indicated.

In certain embodiments, the compound is capable of inhibiting Ubiquitin-like with PHD and RING finger domain 1 (UHRF1). UHRF1 is known to maintain a hetero-chromatic environment via its combined action on both DNA and histone methylations, coordinated through its recruitment of the enzymes catalyzing these epigenetic modifications, and Verdikt et al. (EBioMedicine. 2022, vol. 79, 103985) reported on the role of UHRF1 in the epigenetic repression of the latent HIV-1 viral promoter.

By means of further guidance, human UHRF1 is annotated under U.S. government’s National Center for Biotechnology Information (NCBI) Genbank (http://www.ncbi.nlm.nih.gov/) Gene ID no. 29128, and a human wild-type UHRF1 isoform 2 protein sequence is annotated under Genbank accession no: NP 037414.3. The qualifier “human” as used herein in connection with a UHRF1 protein may in a certain interpretation refer to the amino acid sequence of the UHRF1 protein. For example, a UHRF1 protein having the amino acid sequence as a UHRF1 protein found in humans may also be obtained by technical means, e.g., by recombinant expression, cell-free translation, or non-biological peptide synthesis. A skilled person understands that the amino acid sequence of a given native protein such as a UHRF1 protein may differ between or within different individuals of the same species due to normal genetic diversity (allelic variation, polymorphism) within that species and/or due to differences in post-transcriptional or post-translational modifications. Any such variants or isoforms of the native protein are subsumed by the reference to or designation of the protein.

Any meaningful extent of inhibition of the expression and/or activity of UHRF1 is envisaged. Hence, the terms “inhibit” or “inhibited”, or “downregulate” or “downregulated”, or “reduce” or “reduced”, or “decrease” or “decreased” may in appropriate contexts, such as in experimental or therapeutic contexts, denote a statistically significant decrease relative to a reference. The skilled person is able to select such a reference. An example of a suitable reference may be the UHRF1 expression and/or activity when exposed to a ‘negative control’ molecule, such as a molecule of similar composition but known to have no effects on UHRF1. For example, such decrease may fall outside of error margins for the reference (as expressed, for example, by standard deviation or standard error, or by a predetermined multiple thereof, e.g., ±lxSD or ±2xSD, or ±lxSE or ±2xSE). By means of an illustration, the expression and/or activity of UHRF1 may be considered reduced when it is decreased by at least 10%, such as by at least 20% or by at least 30%, preferably by at least 40%, such as by at least 50% or by at least 60%, more preferably by at least 70%, such as by at least 80% or by at least 90% or more, as compared to the reference, up to and including a 100% decrease (i.e., absent activity as compared to the reference). UHRF1 is a multidomain protein that acts as a key epigenetic regulator by bridging DNA methylation and chromatin modification. Accordingly, the present compounds may in certain embodiments inhibit one or more of the various molecular functions and activities of UHRF1. By means of examples and not limitation, one or more of the following can be inhibited: recognition and binding of UHRF1 to hemimethylated DNA, recruitment of DNMT1 methyltransferase, recognition and binding to histones, in particular to H3 trimethylated at Lys-9 and unmethylated at Arg-2, recruitment of chromatin proteins and/or chromatin modifiers, E3 ubiquitin-protein ligase activity. A skilled person can design in vitro or cell assays to measure such one or more activities of UHRFl.

In certain embodiments, the compound has the structure (I):

wherein,

R¹ is selected from the group consisting of H, OH, OCi-ealkyl, and OC(=O)Ci-6alkyl;

R² is selected from the group consisting of H, OH, OCi-ealkyl, and OC(=O)Ci-6alkyl;

R³ is selected from the group consisting of H, OH, OCi-ealkyl, and OC(=O)Ci-6alkyl;

R⁴ is selected from the group consisting of H, OH, OCi-ealkyl, and OC(=O)Ci-6alkyl;

R⁵ is selected from the group consisting of H, OH, OCi-ealkyl, and OC(=O)Ci-6alkyl;

R⁶ is selected from the group consisting of H, OH, OCi-ealkyl, and OC(=O)Ci-6alkyl;

wherein at least two of R¹, R², R³, R⁴, R⁵, and R⁶ are different from H.

The term “alkyl” by itself or as part of another substituent refers to a hydrocarbyl group of formula C_nH2n+i wherein n is a number greater than or equal to 1. Alkyl groups may be linear or branched and may be substituted as indicated herein. Generally, alkyl groups of this invention comprise from 1 to 6 carbon atoms, preferably from 1 to 5 carbon atoms, preferably from 1 to 4 carbon atoms, more preferably from 1 to 3 carbon atoms, still more preferably 1 to 2 carbon atoms. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. For example, the term “Ci-ealkyl”, as a group or part of a group, refers to a hydrocarbyl group of formula -CnFLn+i wherein n is a number ranging from 1 to 6. Thus, for example, “Ci-ealkyl” includes all linear or branched alkyl groups with between 1 and 6 carbon atoms, and thus includes methyl, ethyl, n-propyl, i-propyl, butyl and its isomers (e.g. n- butyl, i-butyl and t-butyl); pentyl and its isomers, hexyl and its isomers. For example, “Ci-salkyl” includes all includes all linear or branched alkyl groups with between 1 and 5 carbon atoms, and thus includes methyl, ethyl, n-propyl, i-propyl, butyl and its isomers (e.g. n-butyl, i-butyl and t- butyl); pentyl and its isomers. For example, “Ci-4alkyl” includes all linear or branched alkyl groups with between 1 and 4 carbon atoms, and thus includes methyl, ethyl, n-propyl, i-propyl, butyl and its isomers (e.g. n-butyl, i-butyl and t-butyl). For example “Ci-3alkyl” includes all linear or branched alkyl groups with between 1 and 3 carbon atoms, and thus includes methyl, ethyl, n- propyl, i-propyl. A “substituted Ci-ealkyl" refers to a Ci-ealkyl group substituted with one or more substituent(s) (for example 1 to 3 substituent(s), for example 1, 2, or 3 substituent(s)) at any available point of attachment.

In certain embodiments, R², R³, R⁵ and R⁶ are each OH.

In certain embodiments, R¹ is H, and R², R³, R⁵ and R⁶ are each OH.

In some embodiments, said monomeric flavanol-type compound is selected from the group consisting of (+)-catechin, (-)-catechin, (-t-)-epicatechin, (-)-epicatechin, (+)-epigallocatechin, (-)- epigallocatechin, (+)-epicatechin gallate, (-)-epicatechin gallate, (+)-epigallocatechin gallate, (-)- epigallocatechin gallate, (+)-gallocatechin, (-)-gallocatechin, (+)-gallocatechin gallate, (-)- gallocatechin gallate, and mixtures thereof.

In certain embodiments, said monomeric flavanol-type compound is not (-)-epigallocatechin gallate (EGCG).

Preferably, the monomeric flavanol-type compound is chosen from the group consisting of (+)- catechin, (-)-catechin, (+)-epicatechin, (-)-epicatechin, (+)-epigallocatechin, (-)-epigallocatechin, (+)-epicatechin gallate, (-)-epicatechin gallate, (+)-gallocatechin, (-)-gallocatechin, (+)- gallocatechin gallate, (-)-gallocatechin gallate, and mixtures thereof.

In certain preferred embodiments, the monomeric flavanol-type compound is selected from the group consisting of: (+)-catechin, (-)-catechin, (-t-)-epicatechin, (-)-epicatechin, (+)-epicatechin gallate, (-)-epicatechin gallate, (+)-gallocatechin, (-)-gallocatechin, (+)-gallocatechin gallate, (-)-gallocatechin gallate, and mixtures thereof.

In particularly preferred embodiments, the compound is (+)-catechin

(+)-catechin (also known as (+)-cyanidanol-3) can be obtained with high degree of purity (for example, 99.9% or higher degree of purity), for example by extraction from woody plants such as Uncarici gambir or Acacia catechu, first by hot water extraction followed by evaporation, then the residue is purified by submitting it through several stages of recrystallization (see, for example, The Merck Index, 9th Ed., 1976, p. 1901). Highly pure (+)-catechin has been used under the trade name Catergen for the treatment of liver diseases (see, e.g., Blum et al. Lancet. 1977, vol. 310, 1153- 1155).

In certain embodiments, the monomeric flavanol-type compound is in the form of a complex formed by the creation of coordinate bonds with at least one basic amino acid or at least one derivative of a basic amino acid, such as in particular a basic L-amino acid. Reference is made to a complex formed by the creation of coordinate bonds since the weak bases and acids, such as (+)- catechin, are characterized by the fact that, in solution, more than 99% of their concentration is in non-ionic form, which means very few ions in solution and thus substantially no salt formation. The term “a derivative of a basic amino acid” as used herein means, any chemical derivation of a basic amino acid, for instance an addition of a -CH3 or -C2H5 group or else of an amine group.

The basic amino acid may be selected from the group consisting of lysine, arginine, ornithine, citrulline, histidine, pyrolysine, tryptophan, proline, and mixtures thereof. Preferably, said at least one basic amino acid is selected from the group consisting of lysine, arginine, and proline. In certain preferred embodiments, said at least one basic amino acid is lysine or arginine or a mixture of the two. More preferably, the basic amino acid is lysine.

In certain embodiments, the at least one basic amino acid derivative may be a salt of a basic amino acid with an acid. Suitable acids to derivatize such basic amino acids include inorganic acids, which can be selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, and mixtures thereof; also suitable are organic acids such as aliphatic, cycloaliphatic, aromatic or heterocyclic acids. Specific examples of organic acids include carboxylic or sulfonic acids, for example acetic acid, propionic acid, succinic acid, glycolic acid, gluconic acid, lactic acid, malic acid, tartaric acid, citric acid, ascorbic acid, glucuronic acid, maleic acid, fumaric acid, pyruvic acid, aspartic acid, glutamic acid, mandelic acid, methane sulfonic acid, ethane sulfonic acid, pantothenic acid, beta-hydroxypropionic acid, beta-hydroxybutyric acid, malonic acid, galacturonic acid, or mixtures thereof. Preferably, said acid is chosen from the group consisting of ascorbic acid, acetic acid, citric acid, hydrochloric acid, and mixtures thereof. Preferably said acid is hydrochloric acid. Preferably, said at least one basic amino acid derivative is selected from the group consisting of lysine, arginine, and proline hydrochloride. More particularly, the basic amino acid is lysine hydrochloride.

In some embodiments said complex has a molar equivalence ratio between said monomeric flavanol-type compound and said at least one basic amino acid or said at least one derivative of a basic amino acid of between 1:0.25 and 1:5, preferably between 1: 1 and 1:4, preferentially between 1: 1 and 1:3, preferably between 1: 1 and 1:2.5, more preferably between 1: 1 and 1:2.

In some embodiments the molar equivalence ratio is greater than or equal to 1: 1, in particular greater than 1 : 1. In some embodiments, the molar equivalence ratio is less than or equal to 1:3.

In some embodiments the molar equivalence ratio is equal to 1:2 or between 1:2 and 1:4, more preferably between 1:2 and 1:3.

In some embodiments the molar equivalence ratio is less than 1:3, more particularly less than or equal to 1:2.5. Preferably, said molar equivalence ratio is less than 1:2.

Alternatively, the molar equivalence ratio is between 1: 1.5 and 1:2.5, preferably between 1: 1.5 and 1:2. In particular said molar equivalence ratio is greater than or equal to 1: 1 and less than or equal to 1:2.50. More in particular said molar equivalence ratio is greater than or equal to 1: 1 and less than or equal to 1: 1.5.

In some embodiments the molar equivalence ratio is greater than or equal to 1: 1.5 and less than or equal to 1:2. Preferably, said molar equivalence ratio is greater than or equal to 1: 1.5 and less than or equal to 1:2.5.

In particularly preferred embodiments, embodiments, the monomeric flavanol-type compound is in the form of a complex formed by the creation of coordinate bonds with at least one basic amino acid or at least one derivative of a basic amino acid.

In particularly preferred embodiments, the monomeric flavanol-type compound is (+)-catechin, in composition with / in conjunction with / complexed with a basic amino acid, in particular lysine, more in particular L-lysine. Particularly preferably, the molar equivalence ratio between said (+)- catechin and said basic amino acid such as L-lysine may be between 1: 1 and 1:2.5.

The monomeric flavanol-type compound or a stereoisomer, or prodrug thereof (including when complexed with a basic amino acid or derivative thereof) as described herein may be formulated in a pharmaceutical composition. Such compositions may contain, in addition to one or more pharmaceutical actives, at least one pharmaceutically acceptable carrier, diluent or excipient and/or adjuvant.

In some embodiments, the composition comprises at least one monomeric flavanol-type compound, present in the form of a complex formed by the creation of coordinate bonds with at least one basic amino acid or at least one derivative of a basic amino acid; preferably said complex is present in the composition in an amount of between 15% and 95% by weight relative to the total weight of the composition, preferably between 60% and 90%, more preferably from 65% to 85% relative to the total weight of said composition.

In some embodiments the pharmaceutical composition comprises at least one monomeric flavanoltype compound present in the form of a complex with a basic amino acid and/or at least one derivative of a basic amino acid. Preferably, said at least one monomeric flavanol-type compound present in the form of a complex is present in a molar concentration of between 0.01 pM and 5000 pM, preferably of between 0.02 pM and 2500 pM, preferentially between 0.1 pM and 1000 pM, preferably of between 0.5 pM and 500 pM. Preferably, these molar concentrations correspond to a concentration of monomeric flavanol-type compound present in the form of a complex of between 0.0002 mg/ml and 400 mg/ml according to the molecular weight of the monomeric flavanol-type compound in question.

In this respect, in the context of the present invention, it has also been observed, surprisingly, that the complex formed between the monomeric flavanol-type compound and at least one basic amino acid or at least one derivative of a basic amino acid makes it possible to improve, against all expectations, the bioavailability of the composition according to the invention even though the solubility of the composition is also increased via the formation of such a complex. Indeed, as long as the solubility in an aqueous medium is increased, it is expected that the capacity of the complex to cross lipid tissues will be low; however, in the context of the present invention, it has been determined, against all expectations, that the bioavailability is nevertheless increased, also entirely surprisingly, despite the fact that the solubility is increased.

In some embodiments, said composition according to the invention also comprises an acid. The presence of this acid makes it possible to adjust the pH of the composition (as formulated or as formed just before administration) to low values, substantially lower than the natural acidity of the complex. In one embodiment, the pH of the composition is about from 4.0 to 6.0, thereby allowing stabilization of the complex. In one embodiment, the pH of the composition is higher, up to a physiological pH value of about 7.2 to 7.4. In one embodiment, the pH of the composition is adjusted, thus making it possible to stabilize the composition in its galenical form, for example in solution at a physiological pH value of about 7.2 to 7.4. The pH of the composition can also depend on the use of the composition as a medicament, more particularly it can depend on the route of administration envisioned. In one embodiment, the preparation of the compound according to the invention in an injectable form, which can optionally be to be prepared extemporaneously before use, is for example envisioned.

The acid envisioned for reducing the value of the pH in this context can be an inorganic acid, which can be chosen from the group consisting of hydrochloric acid, sulfuric acid or phosphoric acid, or can be an organic acid such as aliphatic, cycloaliphatic, aromatic or heterocyclic acids, which are carboxylic or sulfonic, for example acetic acid, propionic acid, succinic acid, glycolic acid, gluconic acid, lactic acid, malic acid, tartaric acid, citric acid, ascorbic acid, glucuronic acid, maleic acid, fumaric acid, pyruvic acid, aspartic acid, glutamic acid, mandelic acid, methane sulfonic acid, ethane sulfonic acid, pantothenic acid, beta-hydroxypropionic acid, beta-hydroxybutyric acid, malonic acid and galacturonic acid. Preferably, said acid is chosen from the group consisting of ascorbic acid, acetic acid, citric acid, hydrochloric acid, and mixtures thereof. Preferably said acid is hydrochloric acid.

In some embodiments the composition according to the invention is characterized in that, in 0.01 molar solution at 25°C, it has a pH greater than or equal to 3, preferably of between 4 and 11, advantageously of between 4.5 and 9.

In some embodiments, the composition comprises a complex of a catechin with at least one basic amino acid. Preferably, the flavanol may be chosen from the group consisting of (+)-catechin, (-)- catechin, (+)-epicatechin, (-)-epicatechin, (+)-epigallocatechin, (-)-epigallocatechin, (+)- gallocatechin, (-)-gallocatechin, (+)-gallocatechin gallate, (-)-gallocatechin gallate, and mixtures thereof, more preferably the flavanol may be (+)-catechin; and/or the basic amino acid (preferably L-amino acid) may be chosen from the group consisting of lysine, arginine, proline, and mixtures thereof, more preferably the amino acid may be L-lysine.

By means of non-limiting examples, such a formulation may be in a form suitable for oral administration, for parenteral administration (such as by intravenous, intramuscular or subcutaneous injection or intravenous infusion), for topical administration (including ocular), for administration by inhalation, by a skin patch, by an implant, by a suppository, etc. Such suitable administration forms - which may be solid, semi-solid or liquid, depending on the manner of administration - as well as methods and carriers, diluents and excipients for use in the preparation thereof, will be clear to the skilled person; reference is again made to for instance US-A-6,372,778, US-A-6,369,086, US-A-6,369,087 and US-A-6,372,733, as well as to the standard handbooks, such as the latest edition of Remington’s Pharmaceutical Sciences. Some preferred, but non-limiting examples of such preparations include tablets, pills, powders, lozenges, sachets, cachets, elixirs, suspensions, emulsions, solutions, syrups, aerosols, ointments, cremes, lotions, soft and hard gelatin capsules, suppositories, drops, sterile injectable solutions and sterile packaged powders (which are usually reconstituted prior to use) for administration as a bolus and/or for continuous administration, which may be formulated with carriers, excipients, and diluents that are suitable per se for such formulations, such as lactose, dextrose, sucrose, sorbitol, mannitol, starches, gum acacia, calcium phosphate, alginates, tragacanth, gelatin, calcium silicate, microcrystalline cellulose, polyvinylpyrrolidone, polyethylene glycol, cellulose, (sterile) water, methylcellulose, methyl- and propylhydroxybenzoates, talc, magnesium stearate, edible oils, vegetable oils and mineral oils or suitable mixtures thereof. The formulations can optionally contain other pharmaceutically active substances (which may or may not lead to a synergistic effect with the compounds of the invention) and other substances that are commonly used in pharmaceutical formulations, such as lubricating agents, wetting agents, emulsifying and suspending agents, dispersing agents, disintegrants, bulking agents, fillers, preserving agents, sweetening agents, flavoring agents, flow regulators, release agents, etc.. The compositions may also be formulated so as to provide rapid, sustained or delayed release of the active compound(s) contained therein, for example using liposomes or hydrophilic polymeric matrices based on natural gels or synthetic polymers. In order to enhance the solubility and/or the stability of the compounds of a pharmaceutical composition according to the invention, it can be advantageous to employ a-, P- or y-cyclodextrins or their derivatives. In addition, co-solvents such as alcohols may improve the solubility and/or the stability of the compounds.

Appropriate cyclodextrins are a-, - or y-cyclodextrins (CDs) or ethers and mixed ethers thereof wherein one or more of the hydroxyl groups of the anhydroglucose units of the cyclodextrin are substituted with alkyl, particularly methyl, ethyl or isopropyl, e.g. randomly methylated P-CD; hydroxyalkyl, particularly hydroxyethyl, hydroxypropyl or hydroxybutyl; carboxyalkyl, particularly carboxymethyl or carboxyethyl; alkylcarbonyl, particularly acetyl; alkoxycarbonylalkyl or carboxyalkoxyalkyl, particularly carboxymethoxypropyl or carboxyethoxypropyl; alkylcarbonyloxyalkyl, particularly 2-acetyloxypropyl. Especially noteworthy as complexants and/or solubilizers are P-CD, randomly methylated P-CD, 2,6-dimethyl- P-CD, 2-hydroxyethyl-P- CD, 2-hydroxyethyl-y-CD, 2-hydroxypropyl-y-CD and (2-carboxymethoxy)propyl- P-CD, and in particular 2-hydroxypropyl- P-CD (2 -HP- P-CD). The term mixed ether denotes cyclodextrin derivatives wherein at least two cyclodextrin hydroxyl groups are etherified with different groups such as, for example, hydroxypropyl and hydroxyethyl. An interesting way of formulating the compounds in combination with a cyclodextrin or a derivative thereof has been described in EP-A- 721,331. Although the formulations described therein are with antifungal active ingredients, they are equally interesting for formulating the compounds. Said formulations may also be rendered more palatable by adding pharmaceutically acceptable sweeteners and/or flavors. In particular, the present invention encompasses a pharmaceutical composition comprising an effective amount of a compound according to the invention with a pharmaceutically acceptable cyclodextrin. The present invention also encompasses cyclodextrin complexes consisting of a compound according to the invention and a cyclodextrin.

Particular reference is made to the compositions, formulations (and carriers, excipients, diluents, etc. for use therein), routes of administration etc., which are known per se such as those described in US-A-4,997,834 and EP-A-0 370 498.

More in particular, the compositions may be formulated in a pharmaceutical composition comprising a therapeutically effective amount of particles consisting of a solid dispersion of the compounds of the invention and one or more pharmaceutically acceptable water-soluble polymers.

The term “a solid dispersion” defines a system in a solid state (as opposed to a liquid or gaseous state) comprising at least two components, wherein one component is dispersed more or less evenly throughout the other component or components. When said dispersion of the components is such that the system is chemically and physically uniform or homogenous throughout or consists of one phase as defined in thermodynamics, such a solid dispersion is referred to as “a solid solution”. Solid solutions are preferred physical systems because the components therein are usually readily bioavailable to the organisms to which they are administered. The term “a solid dispersion” also comprises dispersions that are less homogenous throughout than solid solutions. Such dispersions are not chemically and physically uniform throughout or comprise more than one phase.

The water-soluble polymer is conveniently a polymer that has an apparent viscosity of 1 to 100 mPa.s when dissolved in a 2% aqueous solution at 20°C solution. Preferred water-soluble polymers are hydroxypropyl methylcelluloses or HPMC. HPMC having a methoxy degree of substitution from about 0.8 to about 2.5 and a hydroxypropyl molar substitution from about 0.05 to about 3.0 are generally water soluble. Methoxy degree of substitution refers to the average number of methyl ether groups present per anhydroglucose unit of the cellulose molecule. Hydroxy-propyl molar substitution refers to the average number of moles of propylene oxide which have reacted with each anhydroglucose unit of the cellulose molecule.

It may further be convenient to formulate the compounds in the form of nanoparticles which have a surface modifier adsorbed on the surface thereof in an amount sufficient to maintain an effective average particle size of less than 1000 nm. Suitable surface modifiers can preferably be selected from known organic and inorganic pharmaceutical excipients. Such excipients include various polymers, low molecular weight oligomers, natural products, and surfactants. Preferred surface modifiers include nonionic and anionic surfactants.

Yet another interesting way of formulating the compounds according to the invention involves a pharmaceutical composition whereby the compounds are incorporated in hydrophilic polymers and applying this mixture as a coat film over many small beads, thus yielding a composition with good bio-availability which can conveniently be manufactured and which is suitable for preparing pharmaceutical dosage forms for oral administration. Said beads comprise (a) a central, rounded, or spherical core, (b) a coating film of a hydrophilic polymer and an antiretroviral agent and (c) a sealcoating polymer layer. Materials suitable for use as cores in the beads are manifold, provided that said materials are pharmaceutically acceptable and have appropriate dimensions and firmness. Examples of such materials are polymers, inorganic substances, organic substances, and saccharides, and derivatives thereof.

The preparations may be prepared in a manner known per se, which usually involves mixing the at least one compound according to the invention with the one or more pharmaceutically acceptable carriers, and, if desired, in combination with other pharmaceutical active compounds, when necessary under aseptic conditions. Reference is again made to US-A-6,372,778, US-A-6,369,086, US-A-6,369,087 and US-A-6,372,733 and the further prior art mentioned above, as well as to the standard handbooks, such as the latest edition of Remington’s Pharmaceutical Sciences.

The pharmaceutical preparations of the invention are preferably in a unit dosage form, and may be suitably packaged, for example in a box, blister, vial, bottle, sachet, ampoule or in any other suitable single-dose or multi-dose holder or container (which may be properly labeled); optionally with one or more leaflets containing product information and/or instructions for use. Generally, such unit dosages will contain between 1 and 1000 mg, and usually between 5 and 500 mg, of the at least one compound of the invention, e.g. about 10, 25, 50, 100, 200, 300 or 400 mg per unit dosage.

The compounds can be administered by a variety of routes including the oral, ocular, rectal, transdermal, subcutaneous, intravenous, intramuscular or intranasal routes, depending mainly on the specific preparation used and the condition to be treated or prevented, and with oral and intravenous administration usually being preferred. The at least one compound of the invention will generally be administered in an “effective amount”, by which is meant any amount of a compound of the formula as taught herein that, upon suitable administration, is sufficient to achieve the desired therapeutic or prophylactic effect in the subject to which it is administered. Usually, depending on the condition to be prevented or treated and the route of administration, such an effective amount will usually be between 0.01 to 1000 mg per kilogram, more often between 0.1 and 500 mg, such as between 1 and 250 mg, for example about 5, 10, 20, 50, 100, 150, 200 or 250 mg, per kilogram body weight day of the patient per day, which may be administered as a single daily dose, divided over one or more daily doses, or essentially continuously, e.g. using a drip infusion. The amount(s) to be administered, the route of administration and the further treatment regimen may be determined by the treating clinician, depending on factors such as the age, gender and general condition of the patient and the nature and severity of the disease/symptoms to be treated. Reference is again made to US-A-6,372,778,US-A-6,369,086, US-A-6,369,087 and US-A- 6,372,733 and the further prior art mentioned above, as well as to the standard handbooks, such as the latest edition of Remington’s Pharmaceutical Sciences.

In accordance with the method of the present invention, said pharmaceutical composition can be administered separately at different times during the course of therapy or concurrently in divided or single combination forms. The present invention is therefore to be understood as embracing all such regimes of simultaneous or alternating treatment and the term "administering" is to be interpreted accordingly.

For an oral administration form, the compositions of the present invention can be mixed with suitable additives, such as excipients, stabilizers or inert diluents, and brought by means of the customary methods into the suitable administration forms, such as tablets, coated tablets, hard capsules, aqueous, alcoholic, or oily solutions. Examples of suitable inert carriers are gum arabic, magnesia, magnesium carbonate, potassium phosphate, lactose, glucose, or starch, in particular, com starch. In this case, the preparation can be carried out both as dry and as moist granules. Suitable oily excipients or solvents are vegetable or animal oils, such as sunflower oil or cod liver oil. Suitable solvents for aqueous or alcoholic solutions are water, ethanol, sugar solutions, or mixtures thereof. Polyethylene glycols and polypropylene glycols are also useful as further auxiliaries for other administration forms. As immediate release tablets, these compositions may contain microcrystalline cellulose, dicalcium phosphate, starch, magnesium stearate and lactose and/or other excipients, binders, extenders, disintegrants, diluents and lubricants known in the art.

When administered by nasal aerosol or inhalation, these compositions may be prepared according to techniques well-known in the art of pharmaceutical formulation and may be prepared as solutions in saline, employing benzyl alcohol or other suitable preservatives, absorption promoters to enhance bioavailability, fluorocarbons, and/or other solubilizing or dispersing agents known in the art. Suitable pharmaceutical formulations for administration in the form of aerosols or sprays are, for example, solutions, suspensions or emulsions of the compounds of the invention in a pharmaceutically acceptable solvent, such as ethanol or water, or a mixture of such solvents. If required, the formulation can also additionally contain other pharmaceutical auxiliaries such as surfactants, emulsifiers and stabilizers as well as a propellant. For subcutaneous or intravenous administration, the compound according to the invention, if desired with the substances customary therefore such as solubilizers, emulsifiers or further auxiliaries are brought into solution, suspension, or emulsion. The compounds of the invention can also be lyophilized and the lyophilizates obtained used, for example, for the production of injection or infusion preparations. Suitable solvents are, for example, water, physiological saline solution or alcohols, e.g. ethanol, propanol, glycerol, in addition also sugar solutions such as glucose or mannitol solutions, or alternatively mixtures of the various solvents mentioned. The injectable solutions or suspensions may be formulated according to known art, using suitable non-toxic, parenterally-acceptable diluents or solvents, such as mannitol, 1,3-butanediol, water, Ringer's solution or isotonic sodium chloride solution, or suitable dispersing or wetting and suspending agents, such as sterile, bland, fixed oils, including synthetic mono- or diglycerides, and fatty acids, including oleic acid.

When rectally administered in the form of suppositories, these formulations may be prepared by mixing the compounds according to the invention with a suitable non-irritating excipient, such as cocoa butter, synthetic glyceride esters or polyethylene glycols, which are solid at ordinary temperatures, but liquefy and/or dissolve in the rectal cavity to release the drug.

In some embodiments the composition is administered once a day, twice a day, three times a day or four times a day. In one embodiment, the administration of a dosage of 50 mg to 2 g/day/patient can be envisioned. More particularly, a dosage of about 250 mg to 750 mg/day, for example 500 mg/day, can be envisioned. It is particularly advantageous to formulate the pharmaceutical compositions envisioned in unit dosage regime form in order to facilitate administration and uniformity of the dosage regime. The unit dosage regime form in the present document refers to physically distinct units that can serve as unit doses, each unit containing a predetermined amount of active ingredient.

Except when noted, “subject” or “patient” are used interchangeably and refer to animals, preferably warm-blooded animals, more preferably vertebrates, even more preferably mammals, still more preferably primates, and specifically includes human patients and non-human mammals and primates. Preferred patients are human subjects including both genders and all age categories thereof. The subject or patient as envisaged herein may in particular require a treatment as taught herein.

As used herein, a phrase such as “a subject in need of treatment” includes subjects that would benefit from treatment of a given condition, particularly of a retroviral infection. Such subjects may include, without limitation, those that have been diagnosed with said condition, those prone to contract or develop said condition and/or those in whom said condition is to be prevented. The terms “treat” or “treatment” encompass both the therapeutic treatment of an already developed disease or condition, such as the therapy of an already developed retroviral infection, as well as prophylactic or preventative measures, wherein the aim is to prevent or lessen the chances of incidence of an undesired affliction, such as to prevent the chances of contraction and progression of a retroviral infection. Beneficial or desired clinical results may include, without limitation, alleviation of one or more symptoms or one or more biological markers, diminishment of extent of disease, stabilised (i.e., not worsening) state of disease, delay or slowing of disease progression, amelioration or palliation of the disease state, and the like. “Treatment” can also mean prolonging survival as compared to expected survival if not receiving treatment. In a preferred embodiment, “treatment” in the light of the present invention implies eradication of latent HIV infected “reservoirs”, with the aim to free the patient from HIV infection.

The term “prophylactically effective amount” refers to an amount of an active compound or pharmaceutical agent that inhibits or delays in a subject the onset of a disorder as being sought by a researcher, veterinarian, medical doctor or other clinician.

The term “therapeutically effective amount” as used herein, refers to an amount of active compound or pharmaceutical agent that elicits the biological or medicinal response in a subject that is being sought by a researcher, veterinarian, medical doctor or other clinician, which may include inter alia alleviation of the symptoms of the disease or condition being treated. Methods are known in the art for determining therapeutically and prophylactically effective doses for the present compounds.

The term “retrovirus” is used herein in its conventional meaning and generally encompasses a class of viruses in which the genetic material is single-stranded RNA and which employ reverse transcriptase to transcribe the viral RNA into DNA in a host. Retroviruses as intended herein may particularly belong to the viral family Retroviridae , more particularly to the sub-family Lentivirinae . Retroviruses as intended herein may be pathogenic (i.e., causing a demonstrable disease phenotype in an infected host) or may be non-pathogenic (i.e., wherein an infected host’s condition does not manifest a demonstrable disease phenotype). Particularly intended herein are retroviruses infecting animals, more preferably retroviruses of warm-blooded animals, even more preferably of vertebrate animals, still more preferably of mammals, yet more preferably of primates, and most preferably of humans. Example retroviruses include human immunodeficiency virus (HIV), human T-lymphotropic virus (HTLV), bovine immunodeficiency virus, bovine leukemia virus (BLV), feline lymphotropic virus-FTLV, simian lymphotropic virus-STLV, etc. Particularly preferred herein are human retroviruses including without limitation HIV-1, HIV-2, HTLV-1 and HTLV-2. The Human Immunodeficiency Virus (HIV) is a lentivirus, part of the family of Retroviridae . It is a single-stranded, positive-sense, diploid, enveloped RNA virus. Once entered in the target cell, the viral RNA genome of the virus is reverse transcribed into double-stranded DNA. This is done through a virally encoded reverse transcriptase that is transported along with the viral genome in the virus particle. After that, the transcribed viral DNA is imported into the cell nucleus and is integrated into the cellular DNA by an integrase (also virally encoded). The latency of the HIV and other lentiviruses is due to their ability to integrate in the host cell genome and stay in there in a latent form, i.e. without replicating. Due to this, the virus avoids detection by the immune system and can stay there for years resulting in a so called “reservoir” of HIV in the infected subject. Once the virus is re-activated, the viral DNA will be transcribed, producing new RNA genomes and viral proteins that are packaged and released from the cell as new virus particles, which can infect new cells. HIV mainly infects cells of the immune system, thereby weakening the immune response of the infected subject, which leads to its name “immunodeficiency virus”. An HIV-positive subject may develop AIDS, or Acquired Immunodeficiency Syndrome, when the virus gets the ability to reproduce. In essence, the HIV will attach and destroy the CD4+ T-cells, macrophages, and microglial cells. The destruction of T-cells and macrophages will make the subject prone to all kinds of normally easy to avoid infections. When CD4+ T-cell numbers drop below the level of 200 cells/pL, the cell-mediated immunity is lost, and infections with a variety of opportunistic microbes appear and Common opportunistic infections and tumors, most of which are normally controlled by robust CD4+ T cell-mediated immunity then start to affect the patient. When a subject with HIV infection or AIDS is not treated, he can eventually die from otherwise easy to cure infections, due to the impairment of the immune system.

Due to the latent character of HIV, reservoirs of HIV-DNA can continue to exist during the whole life span of the infected subject, without any significant signs, if e.g. controlled by constant antiviral treatment. Stopping the treatment will however eventually result in re-activation of the virus. The infected subject can therefore never be fully freed of the HIV infection.

Two types of HIV have been characterized: HIV-1 and HIV-2. HIV-1 is the virus that was initially discovered and is the most virulent type, being more infective, [and the cause of the majority of HIV infections globally. HIV-2 is less infective and implies that fewer of those exposed to HIV-2 will be infected per exposure. HIV-2 is largely confined to West Africa.

In certain embodiments, the retrovirus is a human retrovirus, such as a human pathogenic or non- pathogenic retrovirus. Preferably, the retrovirus is HIV or HTLV, such as a retrovirus selected from the group consisting of: HIV-1, HIV-2, HTLV-1, and HTLV-2. Reference to “retroviral infection” generally encompasses the state or condition of a host as having been infected with the retrovirus. Without limitation, retroviral infection may be typified by the presence of viral biological material in the infected host, e.g., the presence of provirus in the genome of one or more cells of the infected host and/or the presence of viral nucleic acids, viral proteins or viral particles in the infected host. Without limitation, retroviral infection may comprise stages when the provirus is dormant or latent, pre-clinical stages when virus is produced in the infected host but without demonstrable disease symptoms, as well as clinical stages involving demonstrable disease symptoms, such as for example acquired immunodeficiency syndrome (AIDS) caused by HIV-1 and HIV-2, or adult T-cell leukaemia/lymphoma (ATLL) or tropical spastic paraparesis (TSP) caused by HTLV-1.

The present inventors have realized that monomeric flavanol-type compounds, or stereoisomers or prodrugs thereof, optionally in combination with / in complex with basic amino acid(s), can reactivate latent retrovirus. Accordingly, in certain embodiments, the treatment as intended herein induces reactivation of the retrovirus from latency in the treated subject. Such reactivation may for example but without limitation be assessed by detecting increased expression or presence of viral nucleic acids, viral proteins or viral particles in the infected host. Once reactivated, the virus and/or the virus-infected cells can be cleared by the action of the immune system, or can be better managed by antiretroviral therapies, such as established combination antiretroviral therapy (cART).

In certain embodiments, the at least one monomeric flavanol-type compound, or stereoisomer or prodrug thereof, optionally in combination with / in complex with basic amino acid(s), can be used with one or more other therapeutic compound, especially therapeutic compound(s) useful for the treatment of retroviral infection. Hence, the pharmaceutical composition as disclosed herein may contain one or more such additional therapeutic compound, especially therapeutic compound(s) useful for the treatment of retroviral infection.

In certain embodiments, the at least one monomeric flavanol-type compound may be used in combination with one or more retrovirus latency-reversing agent (LRA), one or more retrovirus inducer, and/or one or more antiretroviral therapeutic.

The term “latency reversing agent” or “LRA” as used herein refers to a compound that reactivates latent retrovirus, such as latent HIV virus. Certain classes of latency reversing agents may be useful in the present disclosure. These classes include, but are not limited to, protein kinase C activators, histone deacetylase inhibitors, Toll-like receptor 2 agonists, gamma chain cytokines, or P-TEFb inhibitors. Further latency reversing agents can include an HD AC inhibitor, a phorbol ester, IL-2, and/or a bromodomain inhibitor. Examples of LRAs without limitation includebryostatin 1, prostratin, ingenol B, vorinostat, romidepsin, panobinostat, Pam3CSK4, ALT-803, IL-2, IL-7, IL- 15, heterodimeric IL-15, IL-15N72D-IL-15 receptor alpha Su/Fc fusion protein, JQ1, and/or I- BET151.

Further LRAs can be as disclosed in application WO 2013/050422, including DNA methylation inhibitors, histone deacetylase inhibitors, histone methyltransferase inhibitors, and combinations thereof. Examples of DNA methylation inhibitors include, without limitation, non-nucleoside and nucleoside demethylating agents, including: 5-azacytidine (azacitidine), 5 -aza-2' -deoxy cytidine (5- aza-CdR, decitabine), l-P-Darabinofuranosyl-5 -azacytosine (fazarabine), dihydro-5 -azacytidine (DHAC), 5 -fluorodeoxy cytidine (FdC), oligodeoxynucleotide duplexes containing 2-H pyrimidinone, zebularine, antisense oligodeoxynucleotides (ODNs), MG98, hydralazine, procaine, and/or procainamide.

Examples of histone deacetylase inhibitors include, without limitation, different families of HDACI (hydroxamates, cyclic peptides, aliphatic acids, and benzamides) including TSA, SAHA, MS-275, aminosuberoyl hydroxamic acids, M-Carboxycinnamic acid bishydroxamate, LAQ-824, LBH-589, belinostat (PXD-101), Panobinostat (LBH-589), a cinnamic hydroxamic acid analogue of M- carboxycinnamic acid bishydroxamate, IF2357, aryloxyalkanoic acid hydroxamides, depsipeptide, apicidin, cyclic hydroxamic acid-containing peptide group of molecules, FK-228, red FK, cyclic peptide mimic linked by an aliphatic chain to a hydroxamic acid, butyrate, phenylbutyrate, sodium butyrate, valproic acid, pivaloyloxymethyl butyrate, 5 NOX-275, and/or MGCD0103.

Examples of histone methyltransferase inhibitors, inhibitors include, without limitation, chaetocin, UNC0224, diazepinyl-quinazolinamine, non-SAM (S-adenosylmethionine) analog-based HMTase inhibitor, BIX-01294, BIX-01338 (hydrate), and/or 2-Cyclohexyl-N-(l-isopropylpiperidin-4-yl)-6- methoxy-7 -(3 -(pyrrolidin- 1 -yl)propoxy) quinazolin-4-amine .

Examples of a retrovirus inducer may include a NF-kappa-B-inducer. The term “NF-kappa-B inducers” encompasses all know or yet unknown compounds or agents that can induce or activate NF-kappa-B activity. Preferred examples are Prostratin (12-deoxyphorbol 13-acetate), phorbol myristate acetate (PMA), or Tumour Necrosis Factor alpha (TNF-alpha).

Any retroviral therapies known in the art are contemplated for use in conjunction with the compounds as taught herein, such as anti-retroviral therapies (cART) known in the art (“combination therapy”). Combination therapies as contemplated herein may comprise the administration of at least one active substance of the present invention and at least one other pharmaceutically or biologically active ingredient. Said present active substance(s) and said pharmaceutically or biologically active ingredient(s) may be administered in either the same or different pharmaceutical formulation(s), simultaneously or sequentially in any order. Exemplary anti-retroviral drugs in combination therapy with which the present active substances may be employed include, without limitation, nucleoside and nucleotide reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, protease inhibitors, integrase inhibitors, entry inhibitors, maturation inhibitors and broad spectrum inhibitors. The dosage or amount of the present active substances used, optionally in combination with one or more other active compound to be administered, depends on the individual case and is, as is customary, to be adapted to the individual circumstances to achieve an optimum effect. Thus, it depends on the nature and the severity of the disorder to be treated, and also on the sex, age, body weight, general health, diet, mode and time of administration, and individual responsiveness of the human or animal to be treated, on the route of administration, efficacy, metabolic stability and duration of action of the compounds used, on whether the therapy is acute or chronic or prophylactic, or on whether other active compounds are administered in addition to the agent(s) of the invention.

The herein disclosed aspects and embodiments of the invention are further supported by the following non-limiting examples.

EXAMPLES

Example 1 - Promotion of HIV-1 reactivation from latency by EGCG or by (+)-catechin

The HIV-1 latently infected T-cell line J-Lat 6.3 was mock-treated or treated with increasing doses of epigallocatechin-3 -gallate (EGCG, Sigma #E4143) or (+)-catechin for 24 hours. Following this, HIV-1 reactivation from latency was assessed by flow cytometry (Fig. 1, panel A). The J-Lat cell lines harbours a full-length latent HIV-1 provirus with the gene encoding the enhanced green fluorescent protein (eGFP) in place of nef. The transcriptional state of the HIV-1 promoter can thus be detected in individual cells by flow cytometry. Cellular proliferation was evaluated by the colorimetric test WST-1 according to the manufacturer’s instructions (Roche) (Fig. 1, panel B). The Cell Proliferation Reagent WST-1, based on its cleavage to a soluble formazan depending on the glycolytic production of NAD(P)H in viable cells, was used for the spectrophotometric quantification of cell proliferation and viability in cell populations. Therefore, the amount of formazan dye formed directly correlates with the number of metabolically active cells in the culture.

We observed that EGCG induced HIV-1 transcriptional activation. Unexpectedly, we observed similar or even improved results in terms of HIV- 1 reactivation when cells were stimulated with (+)-catechin, and this without affecting cellular metabolic activity, contrarily to EGCG stimulation, which decreased metabolic activity. The similar or even improved induction of HIV-1 transcription activation by (+)-catechin compared to EGCG is also surprising given that (+)-catechin contains one less aromatic group.

Claims

1. A monomeric flavanol-type compound, or a stereoisomer, or prodrug thereof, for use in a method of treating a retroviral infection.

2. The compound for use according to claim 1, wherein the compound is capable of inhibiting Ubiquitin-like with PHD and RING finger domain 1 (UHRF1).

3. The compound for use according to claim 1 or 2, wherein the compound has the structure (I):

wherein,

4. The compound for use according to claim 3, wherein R², R³, R⁵ and R⁶ are each OH.

5. The compound for use according to claim 3, wherein R¹ is H, and R², R³, R⁵ and R⁶ are each OH.

6. The compound for use according to any one of claims 1-5, wherein said compound is not (-)- epigallocatechin gallate.

7. The composition for use according to any one of claims 1-5, wherein said at least one monomeric flavanol-type compound is selected from the group consisting of: (+)-catechin, (-)- catechin, (+)-epicatechin, (-)-epicatechin, (+)-epicatechin gallate, (-)-epicatechin gallate, (+)-gallocatechin, (-)-gallocatechin, (+)-gallocatechin gallate, and (-)-gallocatechin gallate.

8. The composition for use according to any one of claims 1-5, wherein said at least one monomeric flavanol-type compound is (+)-catechin.

9. The compound for use according to any one of claims 1-8, wherein the compound is in the form of a complex formed by the creation of coordinate bonds with at least one basic amino acid or at least one derivative of a basic amino acid.

10. The compound for use according to claim 9, wherein said complex has a molar equivalence ratio between the compound and said at least one basic amino acid or said at least one derivative of a basic amino acid of between 1: 1 and 1:4.

11. The compound for use according to any one of claims 9-10, wherein said at least one basic amino acid is lysine or arginine of natural or synthetic origin, or a mixture of the two, preferably wherein said at least one basic amino acid is lysine.

12. The compound for use according to any one of claims 9-11, wherein said at least one derivative of a basic amino acid is a salt of the basic amino acid with an acid.

13. The compound for use according to claim 9-12 or the method according to any one of claims 8- 11, wherein said at least one derivative of a basic amino acid is a salt of the basic amino acid with an acid selected from the group consisting of: ascorbic acid, acetic acid, citric acid, hydrochloric acid, and mixtures thereof.

14. A pharmaceutical composition comprising at least one monomeric flavanol-type compound or a stereoisomer, or prodrug thereof, for use in a method of treating a retroviral infection.

15. The pharmaceutical composition for use according to claim 14, wherein said at least one monomeric flavanol-type compound is as defined in any one of claims 2-13.

16. The pharmaceutical composition for use according to any one of claim 14-15, wherein said composition further comprises at least one acid.

17. The pharmaceutical composition for use according claim 16, wherein said acid is selected from the group consisting of ascorbic acid, acetic acid, citric acid, hydrochloric acid, and mixtures thereof.

18. A method for treating a retroviral infection in a subject in need of such treatment, comprising administering to said subject a therapeutically or prophylactically effective amount of a monomeric flavanol-type compound, or a stereoisomer, or prodrug thereof, or a pharmaceutical composition comprising at least one monomeric flavanol-type compound or a stereoisomer, or prodrug thereof.

19. The method according to claim 18, wherein said at least one monomeric flavanol-type compound is as defined in any one of claims 2-13.

20. The method according to claim 18, wherein said pharmaceutical composition is as defined in any one of claims 15-17.

21. The compound for use according to any one of claims 1-13, the pharmaceutical composition according to any one of claims 14-17, or the method according to any one of claims 18-20, wherein said retrovirus is a human retrovirus, such as a human pathogenic or non-pathogenic retrovirus, preferably wherein said retrovirus is HIV or HTLV, such as a retrovirus selected from the group consisting of: HIV-1, HIV-2, HTLV-1, BLV, and HTLV-2.

22. The compound for use according to any one of claims 1-13 and 21, the pharmaceutical composition according to any one of claims 14-17 and 21, or the method according to any one of claims 18-21, wherein the treatment induces reactivation of the retrovirus from latency.

23. The compound for use according to any one of claims 1-13 and 21-22, the pharmaceutical composition according to any one of claims 14-17 and 21-22, or the method according to any one of claims 18-22, wherein said at least one monomeric flavanol-type compound is used in combination with one or more retrovirus latency-reversing agent (LRA), one or more retrovirus inducer, and/or one or more antiretroviral therapeutic.