Conjugates targeting the cation-independent mannose 6-phosphate receptor and bone tissue

Abstract

The present invention relates to novel conjugates having a general formula (I) as defined in claim 1. The conjugates of the invention comprise 1) at least one mannose 6-phosphate (M6P) analog, said M6P analog targeting both the cation-independent mannose 6-phosphate receptor (RM6P-CI) and bone tissue, and 2) a product of interest Y. The invention also relates to the process for preparing said conjugates and their medical use, whether therapeutic or diagnostic. The conjugates of formula (I) of the invention are particularly of interest for use as a drug, especially in the treatment of bone diseases and / or diseases affecting both bone and soft tissue.

Description

Title of the invention: Conjugates targeting the cation-independent mannose 6-phosphate receptor and bone tissue. Technical field

[0001] The present invention falls within the field of medicinal chemistry. It relates more particularly to conjugates comprising: 1 / at least one mannose 6-phosphate (M6P) analogue, said M6P analogue targeting both the cation-independent mannose 6-phosphate receptor (RM6P-CI) and bone tissue and, 2 / a product of interest Y. The invention also relates to the process for preparing said conjugates and their medical use, whether therapeutic or diagnostic. The conjugates of the invention are particularly suitable for use in the treatment of bone diseases and / or diseases affecting both bone and soft tissue. As an example of pathologies affecting both bone and soft tissue, lysosomal diseases such as mucopolysaccharidoses can be cited. Previous technique

[0002] Lysosomal storage diseases, also known as lysosomal storage diseases, are rare metabolic disorders in which a specific lysosomal enzyme is defective, leading to substrate accumulation and thus tissue damage. Enzyme replacement therapy (ERT) is a therapy often used to treat these rare diseases. It consists of administering recombinant lysosomal enzymes that are directed to lysosomes via the RM6P-CI thanks to the M6P residues present at the ends of their glycosylated chains. Only seven of the fifty-three lysosomal storage diseases benefit from enzyme replacement therapy (ERT). Among the lysosomal diseases, the mucopolysaccharidoses group, which includes seven different diseases, is particularly noteworthy and is characterized by involvement of bone tissue, including cartilage and soft tissues.The skeletal involvement in these diseases combines bone deformities and most types of joint stiffness.

[0003] There is currently no effective TES that targets both soft tissue and bone tissue. The challenge of targeting both soft tissue and bone tissue represents a major medical problem, particularly for patients suffering from mucopolysaccharidoses. In order to target both bone and soft tissue, it is necessary to to prepare a new generation of ligands combining efficient bone targeting and moderate targeting of RM6P-CI, in order to avoid accumulation of lysosomal enzymes by soft tissues.

[0004] Lysosomal enzymes have a short half-life in the bloodstream due to their rapid binding to M6P receptors present in most organs. Consequently, improvement of bone tissue damage in patients with mucopolysaccharidoses is very limited, even after long-term treatment, and targeting this bone tissue is therefore of primary importance for improving treatments.

[0005] Hydroxyapatite (HA) is a major inorganic component of bone tissue that is absent in soft tissues. Certain bone tissue proteins (osteopontin, bone sialoprotein, etc.) can bind to hydroxyapatite (HA) via their repeating sequence of negatively charged amino acids, namely the amino acid aspartate (represented by "Asp" or "D") and the amino acid glutamate (represented by "Glu" or "E"). These repeating sequences of six of these amino acids are called E6 and D6 type polyanionic peptides. In the paper Tomatsu, S. et al. (Mol. Gen. Metab. 2015, 114, 94-109), polyanionic peptides have been applied to the human N-acetylgalactosamine-6-sulfatase enzyme (GALNS) and to the [3-glucuronidase] enzyme (GUSB).These enzymes, labeled with E6 and D6 type amino acid sequences, have reduced clearance from the bloodstream in mice with mucopolysaccharidosis type IVA and VII, and are retained longer in bone, with substantial residual enzymatic activity.

[0006] Document WO 2011 / 000958 describes synthetic isosteric analogs of mannose 6-phosphate (M6P) exhibiting an affinity for RM6P-CI ranging from 10⁴ to 10⁹ M. These M6P analogs, called "AMFA" ("Synthetic Analogs of Mannose 6-phosphate Functionalized at the Anomer Position"), were designed to be selectively grafted, via a spacer arm, onto glycoproteins, and more particularly onto the oligosaccharide chains of a lysosomal enzyme. This grafting preserves both the three-dimensional structure of the enzyme and its enzymatic activity. Furthermore, the bifunctional compounds resulting from this grafting exhibit good stability in blood. In the document El Cheikh, K. et al (Angew. Chem. Int. Ed.(2016, 55,14774-14777), an AMFA compound comprising a phosphonate tail was grafted onto the acid alpha-glucosidase (GAA) enzyme via a spacer arm for the treatment of Pompe disease, a lysosomal storage disorder primarily affecting muscles. However, while these compounds may prove promising for the treatment of lysosomal storage diseases, they do not allow for the specific treatment of bone tissue alterations.

[0007] The inventors have now developed new conjugates comprising isosteric analogs of mannose 6-phosphate (M6P) with particularly advantageous properties. An "isosteric of M6P" is understood to mean a synthetic chemical compound exhibiting the same biological activity as M6P but with improved stability. The conjugates of the invention comprise, more particularly, analogs of M6P that exhibit both affinity for the cation-independent mannose 6-phosphate receptor (RM6P-CI) and for bone tissue, and in particular for hydroxyapatite. Furthermore, the conjugates of the invention exhibit excellent stability in physiological fluids. Summary

[0008] According to a first aspect, the present invention relates to a conjugate characterized in that it has the following general formula (I):

[0009] [Chem.l] (I) in which: X represents a bisphosphonate group [Chem2]

[0010] [Chem.2] a hydroxybisphosphonate group [Chem3]

[0011] [Chem.3] a halogen bisphosphonate group [Chem4]

[0012] [Chem.4] with T representing a halogen Cl or F, a malonate group [Chem5]

[0013] [Chem.5] a phosphonoacetate group [Chemô]

[0014] [Chem.6] with Z independently representing H; an alkali metal chosen from Na, Li or K; an ammonium NH4; n is an integer ranging from 0 to 2; Li represents a radical chosen from the group including *-ON=**,

[0015] [Chem7] [Chem. 7]

[0016]

[0017] [Chem8] [Chem. 8] t 1 G And [Chem9] [Chem.9]

[0018]

[0019] with * indicating the point of attachment of Li to the (O-CH2-CH2)n group and ** indicating the point of attachment of Li to Yi; ni is an integer ranging from 1 to 1000, preferably from 1 to 20, and even more preferably from 1 to 10, Yi represents a product of interest Y, said product of interest Y being selected from the group comprising proteins, including antibodies and lysosomal enzymes, nanoparticles, cytotoxic compounds, and markers for medical imaging, Yi forming no covalent bond(s) with Lb According to a second aspect, the present invention relates to a method for preparing a conjugate of formula (I) as defined above. According to a third aspect, the present invention relates to a conjugate of formula (I) for medical use, whether diagnostic or therapeutic. It relates in particular to a conjugate of formula (I) for use as a drug in the treatment of bone diseases and / or diseases affecting both bone and soft tissues. Brief description of the drawings

[0020] Other features, details and advantages will become apparent from reading the detailed description below and from analyzing the accompanying drawings, in which: Fig. 1

[0021] [Fig.1] illustrates the process of preparing the triflate intermediate 6: 2,3,4-tri-O-benzoyl-6-(trifluoromethanesulfonate)-αD-mannopyranoside of 2-bromoethyl, which will serve as a precursor for the synthesis of the compounds of formula (II) designated respectively MAM-1 or 11 and MAM-2 or 14. Fig. 2

[0022] [Fig.2] illustrates the process of preparing the compound of formula (II), designated MAM-1 or 11, in which X represents a bisphosphonate group with Z = H, n is equal to zero and L represents ONH2, from the precursor 6. Fig. 3

[0023] [Fig.3] illustrates the process of preparing the compound of formula (II), called MAM-2 or 14, in which X represents a malonate group with Z = H, n is equal to zero and L represents ONH2, from the precursor 6. Fig. 4

[0024] [Fig.4] illustrates the general synthesis scheme of the conjugates of formula (I) in which ni is equal to 1, depending on the meaning of the reactive chemical group L of the analogue of M6P of general formula (II). Figure 4, point 1, illustrates the reaction between the oxyamine group of the M6P analog of formula (II) and an aldehyde group (-CHO) (previously generated during an oxidative process) of a product of interest Y (such as an antibody or a lysosomal enzyme). Product Y is represented by Yi'-CHO, with Yf representing product Y without its functional group L', which is equal to -CHO. Analog (II) is designated MAM-1 when X is a bisphosphonate group and n is equal to 0, and MAM-2 when X is a malonate group and n is equal to 0. Figure 4, point 2, illustrates the reaction between the squarate group of the M6P analog of formula (II) and an amine group (-NH2) of a product of interest Y. The product of interest Y is represented by Yi'-NH2, where Yf represents Y without its functional group L', which is -NH2. Figure 4, point 3, illustrates the reaction between the maleimide group of the M6P analog of formula (II) and a thiol group (-SH) of a product of interest Y. The product of interest Y is represented by Yi'-SH, where Yf represents Y without its functional group L', which is -SH. Figure 4 illustrates the reaction between the carbonylacrylic group of the M6P analogue of formula (II) and a thiol group of a product of interest Y. Fig. 5

[0025] [Fig.5] illustrates the cytotoxicity on healthy fibroblasts of compounds of formula (II) MAM-1 and MAM-2 are compared with mannose 6-phosphate (M6P) and with an analog of M6P, namely the compound called "AMFA," whose formula is close to that of a compound with formula (II), where n is equal to zero and L is equal to ONH2, but with X representing a phosphonate group -CH2-P(O)(OH)2. The x-axis represents the molar concentration of M6P (black histogram), AMFA (gray histogram), MAM-1 (white histogram), and MAM-2 (hatched histogram). The y-axis represents the cell survival of the compounds. The cell survival observed in the presence of M6P was taken as the value of 100%. Fig. 6

[0026] [Fig.6] illustrates the interactions between RM6P-CI and compounds of formula (II) MAM-1 and MAM-2 compared to M6P and AMFA compounds. The x-axis represents the molar concentration of M6P (dotted line), AMFA (grey line with squares), MAM-1 (black line with circles), and MAM-2 (light grey line with a cross). The y-axis represents the percentage of binding of these compounds to RM6P-Cl. Fig. 7

[0027] [Fig.7] illustrates the adsorption to hydroxyapatite (HA) of compounds of formula (II) MAM-1 and MAM-2 and the compounds M6P, AMFA, zoledronate, and medronic acid. The x-axis represents, from left to right: M6P (black histogram), AMFA (white histogram), MAM-1 (dark gray histogram), MAM-2 (hatched histogram), zoledronate (dotted histogram), and medronic acid (light gray histogram). The y-axis represents the percentage of compounds adsorbed by HA. Fig. 8

[0028] [Fig.8] illustrates the cytotoxicity of the conjugates of the invention on healthy fibroblasts of formula (I), namely Myo-MAM-1 and Myo-MAM-2, compared with the conjugate Myo-AMFA and with the commercial enzyme Myozyme® alone (which is the alpha-alglucosidase enzyme). The x-axis represents the molar concentration of the compounds Myozyme® (black histogram), Myo-AMFA (gray histogram), Myo-MAM-1 (white histogram), and Myo-MAM-2 (hatched histogram). The y-axis represents cell survival in the presence of the compounds. The cell survival observed in the presence of Myozyme was taken as the value of 100%. Fig. 9

[0029] [Fig.9] illustrates the interactions between RM6P-CI and the antibody Infliximab alone or functionalized by the compounds of formula (II) MAM-1 and MAM-2 or by the compound AMFA. The x-axis represents the molar concentration of the compounds M6P (dotted curve on the far right), Infliximab (gray curve with a square pattern), Infliximab-AMFA (gray curve with a triangle pattern), Infliximab-MAM-1 (black curve with a cross pattern), and Infliximab-MAM-2 (light gray curve with an asterisk pattern). The y-axis in each of these figures represents the percentage of binding of the compounds to RM6P-CI. Fig. 10

[0030] [Fig. 10] illustrates the adsorption of the antibody Infliximab, alone or coupled to the compounds of formula (II) MAM-1 and MAM-2 or to AMFA, onto hydroxyapatite (HA). The x-axis represents, from left to right: Infliximab (black histogram), Infliximab-MAM-1 (white histogram), Infliximab-MAM-2 (grey histogram), and Infliximab-AMFA (hatched histogram). The y-axis represents the percentage of compounds adsorbed onto HA. Detailed description

[0031] Formula conjugates (I)

[0032] As indicated, the present invention relates to a conjugate of formula (I) as defined above. For the purposes of this invention, "conjugate" means a compound comprising two parts linked together by a covalent bond. The first part of the conjugate represents at least one M6P analog while the second part of the conjugate Yi represents a product of interest Y chosen from the group including proteins (such as antibodies, lysosomal enzymes, etc.), nanoparticles, cytotoxic compounds and markers for medical imaging. The interest product Y refers to the "free" interest product when it does not form a link with the M6P analogue. The product of interest Yi denotes the product of interest Y when the latter is covalently linked to the M6P analogue via the Lh radical The free product of interest Y can be represented by Yi'-L', with L' representing a functional group or a reactive function carried by the product of interest Y. In other words, Yf represents the product of interest Y without its functional group L'. It is the functional group L' of Y which will react with a functional group or a reactive function carried by the analogue of M6P in order to form a covalent bond between the product of interest Y and the analogue of M6P and thus obtain the conjugate of formula (I) of the invention. In this application, the terms "functional group", "reactive function" or "reactive chemical group" may be used interchangeably. Each of these terms designates a group carried by the product of interest Y (or carried by the analogue of the M6P) capable of reacting with a group carried by the analogue of M6P (or carried by the product of interest Y). In formula (I), the M6P analogue corresponds to the formula delimited by the large parenthesis. The integer ni indicates the number of M6P analogues linked to the product of interest Yb. According to the invention, ni M6P analogues can be covalently linked to a product of interest. These ni M6P analogues are linked to the product of interest via the radical Lb. An M6P analogue is defined as a compound that differs from natural M6P but exhibits a high capacity for interaction with RM6P-Cl. In this application, "interaction" refers to a non-covalent bond. Throughout the application, M6P refers to mannose 6-phosphate and RM6P-CI refers to the cation-independent mannose 6-phosphate receptor. RM6P-CI is a ubiquitous receptor that is present both in the cytoplasm and on the cell membrane. Its role is, in particular, to internalize molecules carrying the recognition marker mannose 6-phosphate (M6P) into the cell via endocytosis. The formula conjugate (I) of the invention is particularly advantageous in that it exhibits several interaction capabilities with several targets such as RM6P-CI, bone tissue or a molecule of therapeutic interest. Thus, the conjugate (I) of the invention exhibits, more specifically, an interaction capacity with RM6P-CI (via the M6P analog), an interaction capacity with bone tissue, more specifically with HA (via the M6P analog and more specifically the X group), but also an interaction capacity with molecules of therapeutic interest via the compound of interest Yb Thus, if the compound of interest Yi is an antibody, then said antibody can interact, for example, with a molecule of therapeutic interest that would be a target antigen. The target antigen refers to a membrane or extracellular molecule of therapeutic or diagnostic interest, in particular a molecule whose overexpression induces a pathological state or is associated with a pathological condition, or whose expression is implicated in a pathological disorder. Examples of molecules of therapeutic interest that interact with compounds of interest Yi include glycosaminoglycans, which accumulate and cause lysosomal storage diseases such as mucopolysaccharidoses; growth factors or membrane proteins involved in cancer growth, particularly in primary bone cancers or cancer metastases in bone tissue; and factors involved in bone pathologies that can be used in imaging for diagnosis or therapeutic targeting. risk of osteoporosis or bone metastases from breast, kidney, prostate, thyroid and lung cancers. Bone tissue refers to a connective tissue that is metabolically active and composed of several cell types and a hard matrix. This matrix is ​​mineralized by calcium and phosphorus salts that constitute hydroxyapatite and contains large amounts of collagen fibers. The "interaction capacity" of the conjugate (I) refers to its ability to form non-covalent interactions with the targets mentioned above, namely: - the RM6P-CI via the M6P analogue, - Bone tissue HA via the X group of the M6P analog, - a molecule of therapeutic interest via the compound of interest Yp. The interaction capacity of the conjugate with its targets can also be referred to as the conjugate's affinity for its targets. Affinity corresponds more specifically to the strength or intensity of the interaction between the conjugate and its targets. The "binding capacity" of the conjugate (I) refers to its ability to form covalent bonds in the case where the Yi part of the conjugate (I) contains a function capable of creating a covalent bond with a molecule of therapeutic interest.

[0033] In the conjugate of formula (I) as defined above, Yi can more particularly be represented by the grouping L2-Y'i in which Y represents the product of interest Y linked to Li via the radical L2, with L2 chosen from the group comprising =CH-, -NH- and -S-, said Yi thus being represented by =CH-Y'i, -NH-Y'i and -S-Y'i The radical L2 is more specifically derived from the transformation of the functional group L' carried by the product of interest Yi when the latter forms a covalent bond with the analogue of M6P.

[0034] According to an advantageous embodiment of the invention, the conjugate of formula (I) is characterized in that ni is an integer equal to 1, and in that said conjugate is chosen from the group comprising:

[0035] [Chem. 10] [Chemll]

[0036] [Chem. 11] [Chem 12]

[0037] [Chem. 12] X.. \ 0« T / ' -X .X x'* \ x^' --- b And [Chem 13]

[0038] [Chem. 13] X., with X, n and Y' i as defined above.

[0039] According to yet another advantageous embodiment, the conjugate of the invention is characterized in that Yi represents an antibody Y, or a fragment of antibody Y comprising at least one antigen interaction domain, or a lysosomal enzyme Y.

[0040] According to one embodiment of the invention, the conjugate (I) is characterized in that Yi represents an antibody Y selected from the group comprising monoclonal antibodies, chimeric antibodies, human or humanized antibodies, heavy and light chain antibodies, single chain antibodies, bispecific or multispecific antibodies and nanobodies.

[0041] According to yet another particularly advantageous embodiment, the conjugate of the invention is more particularly characterized in that Yi represents an antibody Y which is an immunoglobulin of the IgG type, in particular of subtype IgGl, IgG2, IgG3 or IgG4, or an immunoglobulin of the IgE, IgD, IgA or IgM type.

[0042] According to yet another particularly advantageous embodiment, the conjugate of the invention is more particularly characterized in that Yi represents a lysosomal enzyme Y whose expression is altered and involved in mucopolysac-charidoses for which bone growth is altered.

[0043] According to yet another embodiment of the invention, the conjugate of formula (I) as defined above can also be characterized in that it has an affinity, measured by the 50% inhibiting concentration (IC50), for the cation-independent mannose 6-phosphate receptor (RM6P-CI) ranging from 10⁴ M to 10⁹ M, and preferably ranging from 10⁵ M to 10⁸ M.

[0044] According to yet another embodiment of the invention, the conjugate of formula (I) as defined above can also be characterized in that it has an adsorption capacity on hydroxyapatite present in bone tissue.

[0045] The property of double interaction capacity of the conjugates (I) of the invention, namely at the level of the RM6P-CI (and therefore at the level of the endo-lysosomal compartments of the cell) and at the level of bone tissue is in particular due to the judicious choice of the X group of the conjugate of formula (I). Furthermore, the conjugates of the invention are also highly advantageous due to the structure of their spacer arm. The "spacer arm" refers to the portion located after the oxygen atom attached to the anomeric carbon of the cyclic structure of the M6P analog, which merges with the product of interest Yb, namely the portion "-(CH2)2(O-CH2-CH2)n-Lr" (see conjugate of formula (I)). The structure of this spacer arm is particularly simple from a chemical standpoint and allows for efficient grafting with the product of interest. Products of interest Yi considered alone and / or molecules of therapeutic interest interacting with these products of interest Yi are therefore specifically addressed to the endo-lysosomal system and to hydroxyapatite via the conjugates (I) of the invention. The conjugates according to the invention therefore have numerous applications in the field of diagnostics and therapy, and in particular in enzyme replacement therapies combined with a bone-targeting strategy for the treatment of lysosomal storage diseases in humans or animals. These conjugates may also find applications in the treatment of bone cancers or osteoporosis.

[0046] Method for preparing conjugates of formula (I)

[0047] According to another aspect, the present invention relates to a method for preparing a conjugate of formula (I) as defined above, characterized in that the following reaction is performed:

[0048] - a product of interest Y with - nor compound(s) corresponding to the following general formula (II) [Chem. 14]

[0049] (II) in which X, n and ni are as defined above, L is a reactive chemical group chosen from the group comprising -O-NH2, [Chem 15] [Chem. 15]

[0050] [Chem 16] [Chem. 16]

[0051] And [Cheml7] [Chem. 17] O said group L of compound (II) forming neither covalent bond(s) with nor functional group(s) carried by said product of interest Y.

[0052] The compound of formula (II) is an analogue of M6P. It is the reactive chemical group L carried by the analogue of M6P of formula (II) which will react with the functional group L' of the product of interest Y in order to form a covalent bond between the product of interest Y and the analogue of M6P and thus obtain the conjugate of formula (I) of the invention. The L2 radical previously mentioned in relation to Yi (namely Yi is represented by the L2-Y'i group) arises more specifically from the transformation of the L' functional group carried by the product of interest Y (Y being represented by the L'-Y'b group) when Y forms a covalent bond with the M6P analog and is then represented by Yb The compounds of formula (II) are particularly interesting because of the simplicity of their spacer arm. The "spacer arm" refers to the part located after the oxygen on the anomeric carbon of the cyclic structure of the M6P analogue and which includes the reactive chemical group L, namely the part (Ctb^O-Œb-CIDn-L. Indeed, the simplicity of the spacer arm's structure contributes to the advantages offered by the conjugates of formula (I) of the invention. This simplicity of the spacer arm makes it particularly easy to synthesize the compounds of formula (II) and then to achieve a particularly interesting and efficient coupling with a product of interest Y. The synthesis of the conjugates of formula (I) is thus efficient and easy to implement.

[0053] The L groups of the M6P analogue as defined above (in order of appearance) can respectively be referred to in a simplified manner as "oxy-amine", "squarate", "maleimide" and "group comprising a car-bonylacrylic function".

[0054] Analogues of M6P of formula (II) can be represented by the abbreviation "MAM", the acronym MAM meaning "medronic acid mimic".

[0055] According to one embodiment of the invention, the analogues of M6P of formula (II) will be chosen from Table 1 below.

[0056] [Tables 1]

[0057] According to an advantageous embodiment of the process of the invention, the use of the analogues (II) described in Table 1 makes it possible on the one hand to carry out a particularly interesting and efficient coupling with a product of interest Y and on the other hand to interact efficiently with both RM6P-CI and with bone tissue.

[0058] According to another particularly advantageous embodiment, the analogues of formula (II) are those whose group L is an "oxy-amine" or a "squarate".

[0059] According to a particularly advantageous embodiment of the invention, if Y represents for example an antibody or a lysosomal enzyme, the L group of compound (II) will bind at the level of a carbonyl function previously generated on an oligosaccharide chain / part of the glycosidic part of the antibody or lysosomal enzyme. The glycosidic part of the aforementioned antibody is more specifically that located at the Fc region of the antibody. An example of group L of compound (II) is the oxy-amine group.

[0060] According to another embodiment of the invention, group L of compound (II) binds to a suitable amino acid residue of the peptide chain / portion of the antibody or lysosomal enzyme. As an example of a suitable amino acid residue, one could cite an amine group from a lysine or a thiol group from a cysteine. Examples of L groups in compound (II) include a squarate group, a maleimide group, or a carbonylacrylic group.

[0061] Figure 4 illustrates a general synthesis scheme of the conjugates (I) of the invention with X representing a bisphosphonate or a malonate, depending on the respective definitions of the reactive chemical group L of the M6P analogue of general formula (II). As indicated and shown in [Fig. 4], point 1, the carbonyl group (-CHO) of the product of interest Y reacts with the oxyamine group of the compound of formula (II). If Y represents an antibody, this coupling mechanism occurs, for example, at the level of an oligosaccharide chain of the glycosidic portion located on the Fc portion of the antibody. Regarding the coupling mode of the compound of formula (II) comprising the squarate group (see [Fig.4] point 2 / ), if Y represents an antibody, the latter acts for example at the level of a lysine residue of the peptide part of an antibody, namely more particularly at the level of the amine function. Regarding the coupling mode of the compound of formula (II) with a maleimide group (see [Fig.4] point 3 / ), if Y represents an antibody, the latter acts at the level of a cysteine ​​residue of the peptide part of the antibody, namely more particularly at the level of the thiol function. Regarding the coupling mode of the compound of formula (II) comprising a carbonylacrylic function (see [Fig.4] point 4 / ), if Y represents an antibody, the latter acts at the level of a cysteine ​​residue of the peptide part of the antibody, namely more particularly at the level of the thiol function. All these coupling modes are particularly advantageous because they do not create or create little hindrance to the other reactive functions of the antibody (such as the FcRn receptors of the antibody), which advantageously allows the antibody to preserve its natural properties. An antibody has been cited in particular as an example of compound Y. However, the coupling modes on lysine and / or cysteine ​​residues described above are also applicable to all non-glycosylated proteins or peptides.

[0062] Use of conjugates (I) in a therapeutic or diagnostic treatment method

[0063] For the reasons mentioned above, the conjugates (I) of the invention, by virtue of their advantageous properties, are particularly interesting for use in the field of therapy or in the field of diagnostics.

[0064] According to another aspect of the invention, a pharmaceutical composition is proposed, characterized in that it comprises: - a conjugate as defined above, - at least one pharmaceutically acceptable excipient. The conjugate of the invention of formula (I) is present in a therapeutically effective amount in the composition of the invention. A "therapeutically effective amount" refers to a dosage sufficient to produce a desired result, for example, an amount sufficient to achieve beneficial or desired therapeutic (including preventive) outcomes, such as reducing the level of a substance whose extracellular or membrane overexpression is responsible for a disease or is implicated in a pathological condition. An effective amount may require one or more administrations.

[0065] According to yet another aspect, the invention relates to a pharmaceutical composition comprising: - a therapeutically effective amount of the formula conjugate (I), - at least one other therapeutically active agent, - possibly at least one pharmaceutically acceptable excipient.

[0066] The present invention also relates to a conjugate of formula (I) as defined above or a pharmaceutical composition as defined above, for medical use, of a therapeutic or diagnostic type.

[0067] In this regard, the invention relates more particularly to a conjugate of formula (I) as defined above or a pharmaceutical composition as defined above, for use as a drug in the treatment of bone diseases and / or diseases affecting both bone tissue and soft tissue. Examples of bone pathology include: - osteoporosis and osteomalacia, bone dystrophies (such as Paget's disease of bone), osteonecrosis, benign bone tumors (osteomas, osteoblastomas, etc.), benign cartilage tumors (enchondromas, osteochondromas, etc.), certain forms of arthritis (especially osteoarthritis), - certain primary bone tumors that originate in a bone. Some primary bone tumors are malignant, such as adamantinomas and osteosarcomas, which occur in children and adolescents, and chondrosarcomas, chordomas, and malignant giant cell tumors, which are more common in adults. In their early stages, these tumors remain localized to bone tissue but can metastasize to soft tissues, such as the lung, in advanced stages. Examples of pathologies affecting both bone and soft tissue include - certain bone cancers such as Ewing sarcoma, fibrosarcomas and undifferentiated bone lymphomas with a soft tissue component from their training, - bone cancers that develop from metastatic cells that have migrated from a primary tumor located in soft tissue (breast, lung, kidney, prostate, thyroid, colon, etc.), - cancer that develops from the bone marrow such as multiple myeloma, - lysosomal storage diseases such as mucopolysaccharidoses (MPS-I, MPS-II, MPS-III, MPS-IV, MPS-V, MPS-VI and MPS-VII), Fabry disease and Pompe disease.

[0068] According to an advantageous embodiment of the invention, the conjugate or pharmaceutical composition is suitable for use in the treatment of a pathology selected from the group including osteoporosis, bone cancer, lysosomal storage disease.

[0069] The invention also relates to a conjugate of formula (I) as defined above or a pharmaceutical composition as defined above, for use in a diagnostic method.

[0070] According to an advantageous embodiment, the invention relates to the conjugate of formula (I) or the pharmaceutical composition for use as defined above, characterized in that the conjugate or the pharmaceutical composition is in a form suitable for administration by parenteral, intravenous or subcutaneous route. Examples

[0071] The following examples refer to Figures 1 to 10 and describe the synthesis of the M6P analogues of formula (II) and the conjugates (I) of the invention, as well as the study of their biological effects. The M6P analogues of formula (II) of the invention will also be compared to the M6P analogue designated AMFA (a compound notably described in document WO 2011 / 000958) and to the mannose 6-phosphate compound M6P.

[0072] Example 1: Synthesis of M6P analogues

[0073] The M6P analogues synthesized in this example are the compounds of formula (II) designated respectively MAM-1 or 11 and MAM-2 or 14, whose structural formulas are respectively as follows:

[0074] [Chem. 18] HD A j *1^11 [Chem 19]

[0075] [Chem. 19]

[0076] Preparation of synthon 6, a common precursor to compounds MAM-1 and MAM-2. The synthesis of compound 6 (2,3,4-tri-O-benzoyl-6-O- (2-bromoethyl trifluoromethanesulfonyl)-α-D-mannopyranoside”) is illustrated in [Fig. 1]. The starting compound is 1,2,3,4,6-penta-O-acetyl α-D-mannose onto which a bromoethoxy group is introduced at the anomeric position using boron trifluoride diethyl etherate and 2-bromoethanol in dichloromethane to form compound 1 (“2,3,4,6-tetra-O-acetyl-α-D-mannopyranoside”) in 80% yield. The acetates present at positions 2, 3, 4, and 6 of compound 1 are then methanolytically treated in the presence of a sodium methoxide solution in methanol to form compound 2. (2-bromoethyl aD-mannopyranoside) with a 100% yield. Position 6 of derivative 2 is then protected with monomethoxytrityl chloride in pyridine to give intermediate 3 (2-bromoethyl 6-O-methoxytrityl-α-D-mannopyranoside). Positions 2, 3, and 4 are then successively benzoylated by the action of benzoyl bromide to form compound 4 (2,3,4-tri-O-benzoyl-6-O-((4-methoxyphenyl)diphenylmethyl))-α-D-mannopyranoside). Synthon 5 (2-bromoethyl 2,3,4-tri-O-benzoyl-α-D-mannopyranoside) is obtained after selective deprotection of the trityl group in the presence of cerium ammonium nitrate (CAN) in an acetonitrile / water mixture under reflux. The yield over the three steps is 45%. Position 6 of compound 5 is then activated as triflate by the cold addition of triflic anhydride to the sugar in the presence of 2,6-di-terL-butyl-4-methylpyridine. Compound 6 is thus obtained with a 90% yield after purification. Conditions and reagents: (i) BF3.Et2O, 2-Bromoethanol, DCM, TA, 20 h; (ii) MeONa, MeOH, TA, Ih; (iii) MMTrCl, Pyridine, TA, 5 h; (iv) BzCl, Pyridine, 0°C, 19h; (v) CAN, ACN / H2O (95:5), 82°C, 2 h; (vi) Tf2O, 2,6-Di-tert-butyl-4-methylpyridine, DCM, -40°C, 30 min.

[0077] Preparation of the "bisphosphonate" compound MAM-1 fou 11) corresponding to the formula (II) The compound MAM-1 (or 11) corresponds to formula (II) in which X represents a bisphosphonate group with Z = H, n is equal to zero and L represents ONH2, at starting from precursor 6. This compound may be called the "bisphosphonate" compound MAM-1. The synthesis of compound MAM-1 (or 11) is illustrated in [Fig.2]. Synthon triflate 6 is converted to bisphosphonate intermediate 7 (“2,3,4-tri-O-benzoyl-6-deoxy-6-bis(diethoxyphosphinyl)methylene-α-2-bromoethyl mannopyranoside”) by cold-adding a solution of tetraethyl methylenebisphosphonate anion prepared in a sodium hydride (NaH) suspension in tetrahydrofuran (THF). The yield of this step is 50%. Intermediate 8 (2-bromoethyl 6-deoxy-6-bis(diethoxyphosphinyl)methylene-α-D-mannopyranoside) is obtained after methanolysis of the benzoate groups with a methanolic solution of sodium methoxide, in a 50% yield. Compound 9 (2-(phthalimidoxy)ethyl's 6-deoxy-6-bis(diethoxyphosphinyl)methylene-α-D-mannopyranoside) is obtained in 55% yield after nucleophilic substitution of bromine with the α-hydroxyphthalimide anion formed with NaH in hot THF. Silylation of positions 2, 3, and 4 of the intermediate is carried out by adding trimethylsilyl chloride and triethylamine in dichloromethane, to obtain derivative 10 (2,3,4-tri-O-trimethylsilyl-6-deoxy-6-bis(diethoxyphosphinyl)methylene-α-D-mannopyranoside) in quantitative yield. The final product MAM-1 (or 11) (“6-deoxy-6-bis(dihydroxyphosphinyl)methylene-aD-mannopyranoside of 2-aminooxyethyl”) is obtained as a result of two successive deprotection reactions.Initially, the alkyl groups of the bisphosphonate are converted by transesterification into the corresponding trimethylsilyl esters using the Ra-binowitz reaction employing trimethylsilyl chloride TMSC1 in the presence of sodium iodide Nal and triethylamine NEt3 in acetonitrile. Treatment with hydrazine monohydrate in methanol MeOH yields the final MAM-1 (11) with a 2-step yield of 78% after purification. Conditions and reagents: (i) MDPTE, NaH, THF, 0°C, 5 h; (ii) MeONa, MeOH, 0°C, 3h; (iii) A-Hydroxyphthalimide, DBU, THF, 60°C, 4 h; (iv) TMSC1, Et3N, DCM, 0°C, 20 min; (v) TMSC1, Nal, Et3N, ACN, 50°C, 24 h; (vi) N2H4.H2O, MeOH, TA, 24 h.

[0078] Preparation of the compound “malonate” MAM-2 (or 14) corresponding to formula (II) The compound MAM-2 (or 14) corresponds to formula (II) in which X represents a malonate group with Z = H, n is equal to zero and L represents ONH2, from precursor 6. This compound may be called the “malonate” compound MAM-2. The synthesis of compound MAM-2 (or 14) is illustrated in [Fig.3]. Triflate 6 is transformed into compound 12 (“(2,3,4-tri-O-benzoyl-6,7-dideoxy-7-methoxycarbonyl-α-D-manno-octopyranoside of 2-bromoethyl) uronate”) in a yield of 85% after reaction with the dimethyl malonate anion previously prepared by the action of NaH in THF. The bromine atom of compound 12 is then substituted with the N-hydroxyphthalimide anion prepared with sodium bicarbonate NaHCO3 in DMF at 65°C. Compound 13 (“2,3,4-tri-O-benzoyl-6,7-dideoxy-7-methoxycarbonyl-α-manno-octopyranoside of 2-(phthalimidoxy)ethyl) uronate”) is thus obtained in a yield of 92%. Compound 13 is then treated with hydrazine monohydrate in MeOH, then with a NaOH IM solution in THF to produce the final compound MAM-2 (or 14) (“2-aminooxyethyl (6,7-dideoxy-7-carboxy-aD-manno-octopyranoside)uronic acid”) with a yield of 42% over the 2 steps. Conditions and reagents: (i) Dimethyl malonate, NaHCO3, THF, 0°C, 5 h; (ii) N-hydroxyphthalimide, DBU, DMF, 65°C, 22 h; (iii) N2H4.H2O, MeOH, 0°C, 2.5 h; (iv) IM NaOH, THF, 0°C, 2.5 h

[0079] Preparation of compound AMF A The compounds MAM-1 and MAM-2 will be compared in the following to another analogue of M6P, namely the compound called AMFA, whose structural formula is as follows:

[0080] [Chem. 20] HO' V OH o, ^-nh2 O' This AMFA compound is synthesized according to a protocol described in document WO 2011 / 000958. The MAM-1 and MAM-2 compounds differ from the AMFA compound in that the X group is respectively a bisphosphonate in MAM-1 and a malonate in MAM-2 whereas in the AMFA compound the X group is a phosphonate. The compounds MAM-1, MAM-2 and AMFA will also be compared to the commercially purchased compound mannose 6-phosphate (M6P).

[0081] Example 2: Preparation of the conjugates of the invention

[0082] Two products of interest Y, namely a lysosomal enzyme and an antibody, have respectively been functionalized with M6P analogs, namely with the compounds of formula (II) of the invention MAM-1 and MAM-2, but also with the compound AMFA.

[0083] The lysosomal enzyme tested is commercially available under the name Myozyme®. It is the enzyme alpha alglucosidase (or acid alpha glucosidase). It may be referred to hereafter as "Myo". Its structure contains M6P residues that allow targeting of RM6P-CI. The lysosomal enzyme Myo is used for the treatment of Pompe disease by enzyme replacement therapy. The antibody being tested is infliximab, which is a chimeric monoclonal antibody of the IgGl type that does not have M6P residues in its structure. It can be represented hereafter as "Infli".

[0084] The conjugates thus formed may be represented interchangeably in this application by “MAM-1-Myo” or “Myo-MAM-1”, “MAM-2-Myo” or “Myo-MAM-2”, “MAM-1-Infli” or “Infli-MAM-1”, “MAM-2-Infli” or “Infli-MAM-2”, “AMFA-Myo” or “Myo-AMFA”, “AMFA-Infli” or “Infli-AMFA”. The conjugates of the invention are those which comprise the MAM-1 or MAM-2 portion. Advantageously according to the invention the MAM-1 or MAM-2 portion of the conjugate (I) interacts with both RM6P-CI and hydroxyapatite (HA).

[0085] Coupling and quantification of M6P analogues fMAM-L MAM-2 and AMFA) with a product of interest Y (Myo or Infliximab) The coupling of an M6P analogue (MAM-1, MAM-2 and AMFA) with a product of interest Y (Myo or Infliximab) is achieved through the ethyloxyamine function present on the spacer arm of MAM-1, MAM-2 and AMFA, which allows the formation of an oxime-type covalent bond with the aldehyde functions previously generated by controlled oxidation on the oligosaccharide chains of the product of interest Y (Myo or Infliximab). The coupling of a product of interest Y comprising an aldehyde function (generated by oxidation) with a compound of formula (II) comprising a spacer arm with an ethyloxyamine function (therefore with n equal to zero and L= -ONH2) is illustrated in [Fig.4] point 1 / . Oxidation of oligosaccharide chains of the product of interest Y (Myo or I nfliximab) A 0.5 mg / mL concentration of product of interest Y and a 1 mM sodium meta-periodate (NaIO4) solution are reacted in 0.1 M phosphate buffer, pH 6.25, for 30 min at 4°C in the dark. Glycerol (final concentration 272 mM) is added for 5 min at 0°C to stop the reaction, and the sample is filtered through a PD-10 column using 25 mM phosphate buffer, pH 7. Coupling of M6P analogues (MAM-1, MAM-2 and AMFA) with Mvo or In-fliximab After the controlled oxidation step, an excess of M6P analog (MAM-1, MAM-2, or AMFA) is added and incubated for 2 h at room temperature. Finally, the samples are dialyzed in water for the samples tested by MALDI-TOF mass spectrometry or in a buffer containing 25 mM phosphate, 2% mannitol, and 0.005% polysorbate 80 overnight. MALDI-TOF mass spectrometry analysis was used to evaluate the number of M6P analog residues grafted onto the product of interest, Y. Table 2 below shows the average number of grafted M6P analogs, calculated from two MALDI-TOF analyses.

[0086] [Tables2] Conjugates Average number of M6P analogues (m) Infli-AMFA 4.8 Infli-MAM-1 4.6 Infli-MAM-2 3.9 Myo-AMFA 1 Myo-MAM-1 0.9 Myo-MAM-2 1.1

[0087] Remarks and conclusion Under this oxidation condition with ImM NaIO4, the grafting of AMFA, MAM-1, and MAM-2 is estimated at 3.9 to 4.8 M6P analogs per molecule of infliximab and only 0.9 to 1.1 M6P analogs per Myo. This indicates a greater sensitivity to oxidation of the glycosylated chains of infliximab compared to those of Myo, which may be due to differences in the nature of the oligosaccharide chains composing them.

[0088] Example 3: Biological evaluation of M6P analogues The M6P analogues of formula (II) of the invention, namely compounds MAM-1 and MAM-2, were compared biologically to the AMFA analogue and to M6P. Indeed, the compounds AMFA and M6P are known to be non-toxic to cells and to have the ability to interact with RM6P-CI.

[0089] 1 / Evaluation of the cytotoxicity of MAM-1 and MAM-2 analogues The cytotoxicity of MAM-1 and MAM-2 formula (II) analogues was evaluated in comparison with that of M6P and the AMFA analogue on healthy human fibroblasts according to the protocol described below. Experimental protocol: Cells are seeded in 96-well plates (Maxisorp Nunc) in an incubator at 37°C containing 5% CO2. They are then treated with a gradient of concentrations (10³ to 10⁶ M) of analogs. After 72 h, a solution of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) is added, and incubation is continued for 4 h at 37°C. The crystals formed are then dissolved with a DMSO / EtOH (1:1) solution. Cell survival is measured using a spectrophotometer at 540 nm. The results obtained are illustrated in [Fig.5]. This figure shows that the compounds MAM-1, MAM-2, AMFA and M6P are not cytotoxic on the two cell lines even at high concentrations.

[0090] 2 / Affinity of MAM-1 and MAM-2 analogues for RM6P-CI The MAM-1 and MAM-2 analogs were evaluated for their affinity for the RM6P-CI receptor compared to AMFA and M6P. As previously mentioned, affinity refers to the strength of the interaction of the M6P analogs with RM6P-CI. To this end, a competitive interaction assay with RM6P-CI was performed according to the protocol described below. Experimental protocol: Ninety-six-well plates (Maxisorp Nunc) are incubated overnight at 4°C with 200 µL of PM6P (pentamannose 6-phosphate) at a concentration of 200 pg / mL*, in carbonate buffer (0.1 M NaHCO3 / Na2CO3, pH 9.6). The following day, the solution containing residual PM6P is discarded, and the wells are saturated for 1 h at room temperature with 360 µL of 1% gelatin (Type A from Porcine Skin) diluted in PBS (1.9 mM NaH2PO4, 8.1 mM Na2PO4, and 154 mM NaCl, pH 7.4). The wells are then rinsed five times with PBS supplemented with 0.2% gelatin. All washes and dilutions are performed in PBS supplemented with 0.2% gelatin. The compounds to be tested (MAM-1, MAM-2, AMFA, and M6P) at various concentrations (from 10³ to 10⁶ M) are pre-incubated in the presence of previously biotinylated RM6P-CI (RM6PZ?) (2.5 pg.mL⁻¹) for 20 min. Then, 200 pL of the mixture are incubated in the wells for 2 h at room temperature. After 3 washes, the wells are incubated for 1 h with solution 3.108 M of streptavidin-peroxidase. After 3 further washes, 200 pL of a solution containing 1 mg.mL OPD (o-phenylenediamine and 1 pL 30% H2O2.mL in citrate buffer pH 5.0) is added. After 20 min of incubation in the dark and at room temperature, the optical densities are measured at 450 nm. The results obtained are illustrated in [Fig. 6]. The data indicate very high affinities for MAM-1, MAM-2, and AMFA, corresponding to 50% inhibitory concentrations (IC50) of 3.2 x 10⁵ M, 3.0 x 10⁵ M, and 4.5 x 10⁵ M, respectively. By comparison, the affinity of M6P is 2.4 x 10⁵ M in the same experiments.

[0091] 3 / Adsorption of MAM-1 and MAM-2 analogues onto hydroxyapatite The method is based on the inverse determination of the quantity of unbound hydroxyapatite analogs by 31P or ¹H NMR analysis. Two tubes containing equal quantities of analogs are prepared. A defined amount of hydroxyapatite is pre-mixed into one tube, and both tubes are then shaken. After centrifugation, an equal volume of the supernatant from each tube is collected, and a defined amount of standards is added during preparation for NMR analysis. For each tube, the signal area corresponding to the analogs and the standard is measured, and the ratio of the two areas is calculated. The adsorption capacity of the analogs MAM-1, MAM-2, AMFA, and M6P is evaluated using this method and compared to that of commercially available therapeutic compounds used in the treatment of bone diseases, namely zoledronate and medronic acid. The results obtained are illustrated in [Fig.7]. This figure shows that the MAM-1 analog binds completely to hydroxyapatite, just like the therapeutic bisphosphonate derivatives of the prior art (zoledronate and medronic acid). These results are therefore encouraging and promising regarding the ability of the conjugates of the invention comprising such M6P analogs to effectively treat bone diseases. Indeed, even though bisphosphonate derivatives have been previously used to treat bone diseases, nothing suggested to those skilled in the art that an M6P analog of formula (II) with an X group as previously defined would confer a dual interaction capacity, both at the level of RM6P-CI and at the level of HA. The compounds M6P, AMFA and MAM-2, on the other hand, demonstrate a significantly lower HA adsorption capacity than bisphosphonate derivatives, with a value close to 30% for MAM-2.

[0092] Example 4: Biological evaluation of the conjugates of the invention

[0093] The conjugates tested in this example are those previously described in Table 2.

[0094] 1 / Evaluation of the cytotoxicity of Myo-MAM-1 and Myo-MAM-2 conjugates The cytotoxicity of the Myo-MAM-1 and Myo-MAM-2 conjugates of the invention of formula (I) and of the Myo-AMFA conjugate was evaluated in comparison with the lysosomal enzyme Myo alone on healthy human fibroblasts, according to the same protocol as that described in Example 3. The cells were incubated with increasing concentrations (100–1000 ng / mL) of conjugates for 72 h. The results obtained are illustrated in [Fig. 8]. The Myo-MAM-1, Myo-MAM-2, and Myo-AMFA conjugates showed their safety on human fibroblasts.

[0095] 2 / Affinity of the Infli-MAM-1 and Infli-MAM-2 conjugates for RM6P-CI The Infli-MAM-1 and Infli-MAM-2 conjugates of the invention of formula (I) and the Infli-AMFA conjugate were evaluated for their affinity for the RM6P-CI receptor according to the same protocol as that described in Example 3. The results obtained are illustrated in [Fig.9]. It is interesting to note that grafting the MAM-1 and MAM-2 analogs of the invention and the AMFA analog to infliximab yields an antibody with affinity for RM6P-CI, whereas infliximab itself shows no affinity, consistent with the absence of an M6P group in its structure. The affinity of the Infli-AMFA, Infli-MAM-1, and Infli-MAM-2 conjugates is comparable for interaction with RM6P-CI, indicating that the addition of several bispecific analogs of the MAM-1 or MAM-2 type advantageously creates an affinity 10 times greater than that of M6P.

[0096] 3 / Adsorption of the Infli-MAM-1 and Infli-MAM-2 conjugates onto hydroxyapatite The Infli-MAM-1, Infli-MAM-2 conjugates of the invention of formula (I) and the Infli-AMFA conjugate were evaluated for their adsorption capacity on hydroxyapatite according to the same protocol as that described in Example 3. The results obtained are illustrated in [Fig. 10]. The results demonstrate that approximately 28% of infliximab naturally adsorbs to hydroxyapatite (HA). Grafting MAM-1 and MAM-2 analogs to the antibody significantly increases HA adsorption. The 4.6 MAM-1 and 3.9 MAM-2 analogs grafted to infliximab increase in HA adsorption by 20% and 25%, respectively. The equivalent adsorptions of Infli-MAM-1 and Infli-MAM-2 for HA are explained by the multivalence effect generated by the presence of 4,6 and 3,9 MAM grafted onto infliximab since when MAM-2 is considered alone (i.e. when it is not coupled to a product of interest Y) it has a very low affinity for HA (see example 3 [Fig.7]). It is also interesting to note that grafting the AMFA analog onto the antibody does not increase the adsorption of infliximab to HA at all, but on the contrary, decreases it. This further demonstrates the value of the analogs (II) of the invention, which confer particularly advantageous properties to the conjugates (I) of the invention.

[0097] This disclosure is not limited to the examples described above, which are only examples, but encompasses all the variations that a person skilled in the art may consider in the context of the protection sought. List of documents cited Patent documents

[0098] For the sake of clarity, the following patent documents are cited: - patcitl: WO 2011 / 000958. Non-patent literature

[0099] For the sake of completeness, the following non-patent elements are cited: - nplcitl: Tomatsu, S. et al., Mol. Gen. Metab. 2015, 114, 94-109; - nplcit2 : El Cheikh, K. et al Angew. Chem. Int. Ed. 2016, 55,14774-14777.

Claims

Demands

1. Conjugate characterized in that it has the following general formula (I) [Chem.l] (I) in which: X represents a bisphosphonate group [Chem. 2] a hydroxybisphosphonate group [Chem. 3] a halogen bisphosphonate group [Chem. 4] with T representing a halogen Cl or F, a malonate group [Chem. 5] a phosphonoacetate group [Chem. 6] with Z independently representing H; an alkali metal chosen from Na, Li or K; an ammonium NH4; n is an integer ranging from 0 to 2; Li represents a radical chosen from the group including *-ON=**, [Chem. 7] >--NB A > \ / [Chem. 8] % 0-' And [Chem.9] with * indicating the point of attachment of Li to the (O-CH2-CH2)n group and ** indicating the point of attachment of Li to Yi; ni is an integer ranging from 1 to 1000, preferably from 1 to 20, and more preferably-

2.

3. rentiellement encore de 1 à 10, Yi represents a product of interest Y, said product of interest Y being selected from the group comprising proteins, including antibodies and lysosomal enzymes, nanoparticles, cytotoxic compounds, and markers for medical imaging, Yi forming no covalent bond(s) with Lb Conjugated according to claim 1, characterized in that Yi is represented by the group L2-Y'i in which Y represents the product of interest Y linked to Li via the radical L2 with L2 chosen from the group comprising =CH-, -NH- and -S-, said Yi can thus be represented by =CH-Y'i , -NH-Y'i and -S-Y'i. Conjugate according to claim 1 or 2, characterized in that ni is an integer equal to 1 and in that said conjugate of formula (I) is chosen from the group comprising: [Chem. 10] And with X, n and Y' i as defined in claim 1 or 2.

4. Conjugated according to any one of claims 1 to 3, characterized in that Yi represents an antibody Y, or a fragment of antibody Y comprising at least one antigen-interacting domain, or a lysosomal enzyme Y.

5. Conjugated according to claim 4, characterized in that Yi represents an antibody Y which is an immunoglobulin of the IgG type, in particular of subtype IgG1, IgG2, IgG3 or IgG4, or an immunoglobulin of the IgE, IgD, IgA or IgM type.

6. Conjugated according to claim 4, characterized in that Yi represents a lysosomal enzyme Y whose expression is altered and involved in mucopolysaccharidoses for which bone growth is impaired.

7. Conjugated according to any one of claims 1 to 6, characterized in that it has an affinity, measured by the concentration inhibiting 50% (IC50), for the cation-independent mannose 6-phosphate receptor (RM6P-CI) ranging from 10⁴ M to 10⁹ M, and preferably ranging from 10⁵ M to 10⁸ M.

8. Conjugated according to any one of claims 1 to 7, characterized in that it has an adsorption capacity on hydroxyapatite present in bone tissue.

9. A method for preparing a conjugate of formula (I) as defined in any one of claims 1 to 8, characterized in that: - a product of interest Y is reacted with - ni compound(s) corresponding to the general formula (II) (II) in which X, n and ni are as defined in claim 1, L is a reactive chemical group chosen from the group comprising -O-NH2, [Chem. 15] [Chem. 16] O And [Chem. 17] said group L of compound (II) forming neither covalent bond(s) with nor functional group(s) carried by said product of interest Y.

10. Pharmaceutical composition characterized in that it comprises: - a conjugate as defined in any one of claims 1 to 8, - at least one pharmaceutically acceptable excipient.

11. Conjugated as defined in any one of claims 1 to 8 or pharmaceutical composition according to claim 10, for a util- lisation as a drug in the treatment of bone diseases and / or diseases affecting both bone tissue and soft tissues.

12. Conjugated or pharmaceutical composition for use according to claim 11, characterized in that the pathology is selected from the group including osteoporosis, bone cancer, lysosomal storage disease.

13. Conjugated as defined in any one of claims 1 to 8 or pharmaceutical composition according to claim 10, for use in a diagnostic method.

14. Conjugate or pharmaceutical composition for use according to any one of claims 11 to 13 characterized in that the conjugate or pharmaceutical composition is in a form suitable for administration by parenteral, intravenous or subcutaneous route.

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