Prodrug intended for the treatment of bacterial infections resistant to antibiotics of the beta-lactam family

Abstract

The invention relates to the field of antibacterial treatments intended to combat antibiotic-resistant infections. The invention relates more particularly to a prodrug that makes it possible to locally and specifically inhibit a bacterial infection due to a bacterium resistant to antibiotics of the beta-lactam family. This prodrug comprises an antibacterial ingredient from a new therapeutic class, bonded to a bait molecule comprising a functional group that can be cleaved by a beta-lactamase as defined in the classifications of Ambler (1980) and Bush and Jacoby (2010). The antibacterial ingredient is masked, and therefore inactive in the prodrug state, and regains its native structure and antibacterial properties once the prodrug has been cleaved in situ by the pathogenic bacteria.

Description

PRODRUG FOR THE TREATMENT OF BACTERIAL INFECTIONS RESISTANT TO BETA-LACTAM ANTIBIOTICS

[0001] The invention relates to the field of antibacterial treatments intended to combat antibiotic-resistant infections. More particularly, the invention relates to a prodrug for locally and specifically inhibiting a bacterial infection caused by a bacterium resistant to antibiotics of the beta-lactam family. This prodrug comprises an antibacterial principle of a new therapeutic class, and linked to a bait molecule comprising a functional group cleavable by a beta-lactamase as defined according to the classifications of Ambler (1980) and Bush and Jacoby (2010). The antibacterial principle is derived from trans-cinnamaldehyde; it is masked and therefore inactive in the prodrug state and regains its native structure and its antibacterial properties once the prodrug is cleaved, in situ, by the pathogenic bacteria. Field of invention

[0002] The fight against bacterial infections is a public health concern when it comes to dealing with multi-resistant bacteria. Indeed, many bacteria have developed resistance mechanisms to conventional antibiotics, particularly those of the beta-lactam family. To treat these infections, second-generation antibiotics are administered, but these are responsible for side effects. Also, their systemic use (i.e., non-local and non-specific) promotes the emergence of new resistance against these new molecules.

[0003] Strategies for targeting antibacterial molecules to the site of infection of antibiotic-resistant bacteria have been proposed, notably by exploiting the resistance mechanism implemented by the bacteria to target the treatment. Such an approach was described by Evanset al. (J. Med. Chem 2019, 62, 4411-4425); it consists of a prodrug activatable by beta-lactamases produced by resistant bacteria. Thus, a classic antibiotic molecule, ciprofloxacin, is chemically conjugated to a beta-lactam motif recognized by the bacteria and cleaved by it so as to release said antibiotic molecule. However, the specificity of this prodrug may be limited by the fact that the molecular structure of the antibiotic agent is in its “active” form within the prodrug. Thus, it is expected that an antibiotic activity, even reduced, is exerted by the prodrug even before its cleavage by beta-lactamases.This limits the specificity of action of this prodrug on multi-resistant bacteria, which is essential to avoid systemic exposure and to "give a chance" to bacteria that are not already multi-resistant to develop resistance mechanisms. While this system allows for localized antibacterial action at the site of infection, it does not provide a solution to the problem of antibiotic resistance.

[0004] There is a real need for new therapeutic strategies to treat infections caused by antibiotic-resistant bacteria. Solutions to this need must integrate (1) a new therapeutic target and (2) a specific and local action to avoid systemic exposure and the development of resistance.

[0005] The inventors propose a new therapeutic strategy in the fight against antibiotic-resistant bacteria. This approach is based on the antibacterial effect of small molecules targeting a new molecular target and whose mechanism of action is not countered by the classic defense or resistance systems developed by bacteria, such as certain molecules derived from essential oils. However, since these molecules are unstable and their bioavailability is low, an innovative delivery system must be associated with them so that the therapeutic solution according to the invention is in the form of a prodrug. This approach consists of a prodrug that allows the localized delivery of the active molecule only at the site of interest, the site of infection comprising resistant bacteria, due to a specific enzymatic reaction of multi-resistant bacteria capable of cleaving the prodrug.This avoids any harmful systemic effects of the active ingredient.

[0006] Thus, a first subject of the invention relates to a prodrug intended to be used in the treatment of bacterial infections resistant to antibiotics of the beta-lactam family comprising an antibacterial principle linked to a bait molecule containing a functional group cleavable by a beta-lactamase, characterized in that it corresponds to formula (I):

[0007] (I)

[0008] in which

[0009] X is either absent or a spacer group is chosen from a phenylene, alkenylene or alkynylene group.

[0010] R1 is a group selected from alkyl, alkylsulfonylethyl or alkylaminoethyl, for example methyl, methylsulfonylethyl or dimethylaminoethyl

[0011] R2 is a group chosen from methyl, 2,2,2-trifluoroethyl,

[0012] R3 is a masked antibacterial principle, said masked active principle corresponding to the structural body of trans-cinnamaldehyde devoid of its aldehyde function or one of the variants of this structure having retained antibacterial activity,

[0013] R4 is a beta-lactam group.

[0014] A second subject of the invention relates to a pharmaceutical composition comprising a prodrug according to the invention and at least one pharmaceutically acceptable excipient.

[0015] A third subject of the invention relates to the use of a prodrug according to the invention in the treatment of bacterial infections resistant to antibiotics of the beta-lactam family. Advantages of the invention

[0016] The present invention differs from existing solutions by the choice of the antibacterial active ingredient and by the fact that this active ingredient is masked within the prodrug (and therefore rendered inactive in the prodrug form). Indeed, the inventors have developed an approach making it possible to exploit the antibacterial properties of small molecules whose instability and low bioavailability have until now been an obstacle to their therapeutic use, as is the case for those derived from essential oil (EO). The latter are known for their antibacterial activity and because of their novel mechanism of action, which is not likely to induce resistance in bacteria. Thus, the invention aims to provide a new class of effective and safe antibacterial (pro-)drugs (no induction of new resistance) to treat infections caused by bacteria resistant to beta-lactams.

[0017] The drug object of the invention is in the form of a prodrug which comprises the antibacterial principle derived from a small molecule carrying an aldehyde function; this function is exposed to multiple mechanisms of rapid modification by the patient's metabolism which result in a low bioavailability of said small molecules. To ensure their arrival at the site of the infection, they must be incorporated into molecular structures showing suitable stability, water solubility and bioavailability. The active principle is thus modified by conjugation to a bait molecule. Another advantage of this system is that it masks the activity of the active principle but ensures its release in the presence of a bacterium resistant to antibiotics of the beta-lactam family. Once released, the molecule regains its active form and its antibacterial properties.Delivery of the active ingredient is therefore targeted to the site of infection, and avoids the side effects and risks of resistance development associated with systemic distribution of the antibacterial agent.

[0018] The release of the active ingredient is dependent on the action of the resistant bacteria. Indeed, the prodrug comprises a group recognized by beta-lactamases secreted by the resistant pathogenic bacteria, which catalyze the cleavage of the prodrug's bait molecular unit, the beta-lactam unit. The collapse of the latter releases the antibacterial principle and releases an active molecule at the site of infection. The prodrug therefore acts as a Trojan horse because the bacteria, by activating its defense system - the secretion of a beta-lactamase enzyme - induces the release of the antibacterial molecule which will destroy and / or inhibit it.

[0019] In more detail, the prodrug comprises, between the beta group and the active ingredient (R3 group), an N / O-acetal-oxycarbonyl group linked to a spacer group X. It is this N / O-acetal-oxycarbonyl group which ensures the incorporation and masking of the active ingredient, as well as its release following the collapse of the prodrug caused by the action of the target enzyme. This is an original element of the structure of the prodrug, on which the innovative properties of the invention are based with respect to similar prodrug molecules of the prior art: the release is effective but the prodrug is stable to spontaneous hydrolytic degradation in the absence of the target enzyme. This property also ensures that the prodrug cannot exert an intrinsic antibiotic action since the structure of the active ingredient is not found in the absence of cleavage.It is these two properties which make it possible to propose a clinical use of the prodrugs according to the invention.

[0020] The system according to the invention is therefore based on a local, immediate and specific action of an antibacterial molecule from a new therapeutic class which is not likely to induce new resistance. An example of such a molecule is trans-cinnamaldehyde, an active ingredient derived from cinnamon essential oil. DETAILED DESCRIPTION OF THE INVENTION

[0021] A first subject of the invention relates to a prodrug intended to be used in the treatment of bacterial infections resistant to antibiotics of the beta-lactam family comprising an antibacterial active ingredient linked to a bait molecule comprising a functional group cleavable by a beta-lactamase, characterized in that it corresponds to formula (I):

[0022] (I)

[0023] in which:

[0024] X is either absent or a spacer group is chosen from a phenylene, alkenylene or alkynylene group.

[0025] R1 is a group selected from alkyl, alkylsulfonylethyl or alkylaminoethyl, for example methyl, methylsulfonylethyl or dimethylaminoethyl

[0026] R2 is a group chosen from methyl, 2,2,2-trifluoroethyl,

[0027] R3 is a masked antibacterial principle, said masked active principle corresponding to the structural body of trans-cinnamaldehyde devoid of its aldehyde function or one of the variants of this structure having retained antibacterial activity,

[0028] R4 is a beta-lactam group.

[0029] The term "prodrug" refers to a precursor drug, also known as a "prodrug." It is an inactive / low-active form of a molecule that is metabolized in vivo into an active metabolite. In the present invention, the prodrug consists of a masked antibacterial principle and a bait molecule; the antibacterial principle is therefore the metabolite.

[0030] The active ingredient is a small molecule drug with antibacterial properties. It is hidden in the prodrug, meaning it is in an inactive form. Such an active ingredient can be derived from different types of plants, including plants or lichens, and can in particular be derived from an essential oil, or from animals, particularly marine animals.

[0031] In a preferred embodiment of the invention, the antibacterial active ingredient is derived from an EO whose antibacterial properties are known, trans-cinnamaldehyde as represented below or one of its variants. By "trans-cinnamaldehyde variant" is meant a molecule which has the same structural body as cinnamaldehyde, which has a similar, identical or superior antibacterial activity and / or which confers increased stability to the prodrug. Such variants may in particular be substituted at the phenyl unit, for example by replacing an H with a methoxy, ethoxy group, an alkylamino group such as a dimethylamino, or an acylamino group.

[0032] cinnamaldehyde

[0033] Within the prodrug, the active ingredient is rendered inactive by masking its aldehyde function. This modification has two functions: it allows binding to the bait molecule and masks (temporarily suppresses) the antibacterial activity of the active ingredient while it is in the prodrug form.

[0034] In the context of the present invention, the masking is carried out by transforming the aldehyde function into an N / O acetal whose nitrogen atom is acylated (more precisely “oxy-carbonylated”) in order to give the acetal increased stability against any spontaneous hydrolysis (degradation), and in order to allow the release of this oxy-carbonylated N / O acetal in the form of carbamate (good leaving group) upon activation by a target beta-lactamase of the bait portion of the prodrug. “R3” then represents a phenyl-vinyl unit.

[0035] For the purposes of the invention, the term "bait molecule" means a group recognized by bacteria and capable of inducing the activation of the defense functions of bacteria against antibiotics of the beta-lactam family. These defense functions consist of the secretion of an enzyme capable of cleaving the beta-lactam nucleus present in this family of antibiotics.

[0036] The bait molecule according to the invention comprises an R4 group recognized by beta-lactam-resistant bacteria. This R4 group is a beta-lactam group that mimics the presence of an antibiotic. As explained previously, the recognition of this group acts as a trigger signal for the secretion of a beta-lactamase by the bacteria, which acts in defense. The bait molecule also comprises the central group of formula (I) (N / O-acetal-oxycarbonyl group) and optionally a spacer group X. .

[0037] One of the particularly innovative aspects of the invention lies in the structure of the cleavable functional group - which corresponds to the central N / O-acetal-oxycarbonyl group of formula (I) - which fulfills three functions: (i) the binding of the active ingredient with a beta-lactam group, (ii) the masking of the antibacterial activity of the active ingredient by its incorporation into the N / O acetal oxycarbonyl unit and (iii) the activation of the antibacterial activity by cleavage of the beta-lactam group after secretion of a beta-lactamase by the bacteria and then the self-collapse of the structure which results in the release of the active ingredient in a restored active form which exerts new class antibiotic properties. Indeed, it is remarkable to note that the cleavable group has the property of allowing the active ingredient which has been modified to synthesize the prodrug, to regain its native form and its antibacterial properties after being released.Here, the active ingredient carries an aldehyde function which is linked to the bait molecule at R3, as shown in formula (I). The aldehyde function of the active ingredient is reformed in situ. This mechanism of action is illustrated in.

[0038] In a preferred embodiment of the invention, the beta-lactam group (R4 group) is derived from a cephalosporin, a penicillin or a carbapenem. This group is cleavable by a beta-lactamase; the latter may be a carbapenemase.

[0039] There are many R4 groups described in the literature and those skilled in the art will be able to identify them. As a particular example, cefalotin can be cited.

[0040] cefalotin

[0041] The group R4 can be more generally represented by the following formula (II):

[0042] (II)

[0043] in which R7 is chosen from alkyl, benzyl, substituted or unsubstituted aryl groups.

[0044] Examples of particular R7 groupings are illustrated below:

[0045] The spacer group X allows the properties of the prodrug to be modulated depending on the choice of the group X and the active ingredient associated in the prodrug. Its presence is optional. In the configuration where the group X is absent, the group R4 is directly linked to the N / O-acetal-oxycarbonyl group.

[0046] Examples of prodrugs according to the invention are the molecules OSTA-1, OSTA1b, OSTA-5, OSTA-6 and OSTA-7 represented below:

[0047] OSTA-1

[0048] OSTA-1b

[0049]

[0050]

[0051]

[0052] A second subject of the invention relates to a pharmaceutical composition comprising a prodrug as defined above and at least one acceptable excipient.

[0053] A third subject of the invention relates to the use of a prodrug as defined above in the treatment of bacterial infections resistant to antibiotics of the beta-lactam family.

[0054] Bacterial infections resistant to beta-lactam antibiotics are caused primarily by Gram-negative bacteria that can produce beta-lactamases. However, some Gram-positive bacteria, such as MRSA, can also produce beta-lactamases.

[0055] The following are particularly targeted by the prodrugs according to the invention:

[0056] - Gram-negative bacteria belonging to the following families: Moraxellaceae, Legionellaceae, Enterobacteriaceae, Pseudomonadaceae, Alcaligenaceae, Sphingomonadaceae, Pasteurellaceae, Neisseriaceae, Pasteurellaceae, Flavobacteriaceae, Bacteroidaceae, Fusobacteriaceae, Burkholderia cepacea, Cronobacter malonaticus, Cronobacter sakazakii, Helicobacter pylori, Micrococcus luteus, Prevotella, Proteus mirabilis, Proteus vulgaris G, Salmonella enteritidis G-, Salmonella enterica serovar typhi, Salmonella typhimuriu, Salmonella enterica serovar paratyphi A, Vibrio fluvialis (MDR), Vibrio parahaemolyticus, Acinetobacter baumannii,

[0057] - les bactéries Gram négatives appartenant à l'un des genres suivants : Klebsiella, Serratia, Citrobacter, Salmonella, Shigella, Proteus, Haemophilus, Campylobacter, Legionella, Sphingomonas, Moraxella, Kingella, Pasteurella, Capnocytophaga, Neisseria, Bacteroides, Enterobacter, Pseudomonas, Fusobacterium, Achromobacter, Escherichia et Acinetobacter,

[0058] - les bactéries Gram négatives appartenant à l'une des espèces suivantes : Klebsiella pneumoniae, Klebsiella oxytoca, Acinetobacter baumannii, Acinetobacter calcoaceticuS, Serratia marcescens, Citrobacter freundii, Citrobacter koseri, Haemophilus influenzae, Haemophilus parainfluenza, Campylobacter jejuni, Campylobacter coli, Legionella pneumophila, Legionella longbeachae, Legionella bozmanii, Legionella micdadei, Enterobacter cloacae, Escherichia coli, Escherichia hermannii, Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas stutzeri, Achromobacter xylosoxidans, Achromobacter denitrificans, Sphingomonas paucimobilis, Moraxella catarrhalis, Kingella kingae, Pasteurella multicida, Capnocytophaga canimorsus, Neisseria gonorrhoeae, Neisseria actamica and Bacteroides fragilis

[0059] - en particulier les bacteria Pseudomonas aeruginosa et Acinetobacter baumannii (notamment Acinetobacter baumannii 5377 ou Acinetobacter baumannii mucoïde). Les bacteria gram positive suivantes :

[0060] Families: Staphylococcaceae, Micrococcaceae, Streptococcaceae, Enterococcaceae, Bacillaceae, Clostridiaceae, Listeraceae, Corynebacteriaceae

[0061] Genre: Staphylococcus, Micrococcus, Streptococcus, Enterococcus, Bacillus, Clostridium, Listeria, Corynebacterium

[0062] Species (examples): Staphylococcus aureus, Staphylococcus epidermitis, Staphylococcus saprophyticus, Micrococcus luteus, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus pneumoniae, Streptococcus viridans, Enterococcus faecalis, Enterococcus faecium, Bacillus anthracis, Clostridium difficile, Listeria monocytogenes, Corynebacterium diphteriaeOther non-Gram-staining bacteria:

[0063] Families:Mycobacteriaceae;

[0064] Genus: Mycobacterium

[0065] Species: Mycobacterium tuberculosis, Mycobacterium leprae, Mycobacterium abscessus, Mycobacterium ulcerans

[0066] These infections particularly affect the digestive tract, the urinary tract, the pulmonary tract, or the skin and mucous membranes and can affect a specific organ or be generalized. The prodrugs according to the invention can be used to treat all these forms of infection.

[0067] Examples of infection (with or without comorbidity such as genetic factors, immunosuppression, etc.) for which the molecules according to the invention are particularly interesting are respiratory tract infections (with or without comorbidity): Pneumonia, PAH, VAP, tuberculosis, sinusitis, cystic fibrosis; blood or blood-borne infections: Bacteremia, Septicemia; Urinary tract infections: Cystitis, Pyelonephritis; skin and soft tissue infections: Abscesses, boils, impetigo, chronic wounds, necrotizing infections; surgical site infections; infections related to a prosthesis, a medical device (probe, catheter, etc.); gastrointestinal infections; sexually transmitted infections; infections of the central or peripheral nervous system, heart, eyes, ears, mouth, bones and joints.

[0068] The present invention will be better understood from the following examples, provided for illustration purposes and in no way to be considered as limiting the scope of the present invention. DESCRIPTION OF FIGURES

[0069] : Representation of the synthesis process of the prodrug OSTA-1

[0070] : UV absorbance spectrum at 285 nm of the OSTA-1 molecule in vitro.

[0071] : Mechanism of activation of the active principle after collapse of the prodrug OSTA-1 EXAMPLES EXAMPLE 1: Synthesis of the OSTA-1 molecule

[0072] The synthesis protocol of the prodrug molecule OST1 includes 5 steps and two auxiliary steps. It is shown in.

[0073] EXAMPLE 2: Functional analysis of the OSTA-1 molecule A - In vitro cleavage of the OSTA-1 molecule

[0074] The cleavage of the prodrug OSTA-1 was tested in vitro by contact with a beta-lactamase in an aqueous saline medium.

[0075] Experimental conditions:

[0076] The cleavage test is performed in a physiological saline buffer (Phosphate Buffer Saline, PBS) at pH 7.0. The OSTA-1 molecule is added at a concentration of 100 microM as well as the commercial beta-lactamase at a concentration of 1 unit per mL. Incubation is carried out at 37°C. The appearance of free trans-cinnamaldehyde in the medium is then monitored by UV absorption at 285nm.

[0077] The results are presented in the.

[0078] The release of the active ingredient, here trans-cinnamaldehyde, was monitored by UV absorption at 285nm. The evolution of the release of the active ingredient (100microM) from the prodrug molecule is observed, in the presence and absence of beta-lactamase. It clearly appears that the active ingredient is released in significant quantities after two hours of reaction in the presence of beta-lactamase. In the absence of beta-lactamase, no spontaneous release of the active ingredient is observed.

[0079] Conclusion: The prodrug molecule OSTA-1 works as expected: it is cleavable by beta-lactamase and allows the release of the active ingredient.

[0080] B – Activation of the active ingredient after collapse of the prodrug

[0081] The mode of activation of the active ingredient is illustrated in which shows the mechanism of collapse of the prodrug OSTA-1 and the release of cinnamaldehyde in its active native form.

Claims

Prodrug intended for use in the treatment of bacterial infections resistant to beta-lactam antibiotics comprising an antibacterial active ingredient linked to a bait molecule containing a functional group cleavable by a beta-lactamase, characterized in that it corresponds to the formula (I): (I) in which X is either absent, or a spacer group is chosen, a phenylene, alkenylene or alkynylene group. R1 is a group chosen from an alkyl, an alkylsulfonylene or an alkylaminoethyl, for example a methyl, a dimethyl, a methylsulfonylene or a dimethylaminoethyl. R2 is a group chosen from a methyl, a 2,2,2-trifluoroethyl. R3 is a masked antibacterial principle, said masked active principle corresponding to the structural body of trans-cinnamaldehyde deprived of its aldehyde function or one of the variants of this structure having retained antibacterial activity. R4 is a beta-lactam group. Prodrug according to claim 1, wherein said R4 group is a derivative of cephalosporin, penicillin or carbapenem. Prodrug according to one of the preceding claims, in which said group X is absent. Prodrug according to one of the preceding claims selected from the molecules OSTA-1, OSTA-1b, OSTA-5, OSTA-6 or OSTA-7. Pharmaceutical composition comprising a prodrug according to one of claims 1 to 4 and at least one acceptable excipient. Prodrug as defined in any one of claims 1 to 4 for its use in the treatment of bacterial infections resistant to beta-lactam antibiotics.

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