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) analogue, the M6P analogue targeting both the cation-independent mannose 6-phosphate receptor (CI-MPR) and bone tissue; and 2 / a product of interest Y. The invention also relates to the method for preparing the conjugates and to the therapeutic or diagnostic medical use thereof. The conjugates of formula (I) of the invention are particularly beneficial for use as a medicament, in particular in the treatment of bone diseases and / or diseases affecting both bone tissue and soft tissue.

Description

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

[0001] The present invention relates to the field of therapeutic 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 (CM6P-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, of a therapeutic or diagnostic type. The conjugates of the invention are particularly suitable for use in the treatment of bone pathologies and / or pathologies affecting both bone tissue and soft tissues. Examples of pathologies affecting both bone and soft tissue include lysosomal diseases such as mucopolysaccharidoses. Prior art

[0002] Lysosomal storage diseases, also known as lysosomal storage diseases, are rare metabolic diseases in which a specific lysosomal enzyme is defective, leading to substrate accumulation and therefore tissue damage. Enzyme replacement therapy (ERT) is a therapy often used to treat these rare diseases. It consists of the administration of recombinant lysosomal enzymes that are directed to lysosomes via RM6P-CI thanks to the M6P residues present at the end of their glycosylated chains. Only seven of the fifty-three lysosomal storage diseases benefit from enzyme replacement therapy (ERT). Among the lysosomal storage diseases, we can particularly mention the group of mucopolysaccharidoses, which includes seven different diseases, and which is characterized by damage to bone tissue, including cartilage and soft tissue.The skeletal involvement of 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 represents a major medical problem for patients suffering especially from mucopolysaccharidoses. In order to target both bone and soft tissue, it is necessary to prepare a new generation of ligands combining bone targeting effective 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 the rapid binding of lysosomal enzymes to M6P receptors present in most organs. Therefore, 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. Some bone tissue proteins (osteopontin, bone sialoprotein, etc.) can bind to hydroxyapatite (HA) via their negatively charged amino acid repeating sequence, namely the amino acid aspartate (represented by "Asp" or "D") and the amino acid glutamate (represented by "Glu" or "E"). These repeating sequences chaining six of these amino acids are called E6 and D6 type polyanionic peptides. In Tomatsu, S. et al. (Mol. Gen. Metab. 2015, 114, 94-109), polyanionic peptides were applied to human N-acetylgalactosamine-6-sulfatase (GALNS) enzyme and P-glucuronidase (GUSB) enzyme.These enzymes, labeled with E6- and D6-like amino acid sequences, have reduced clearance from the bloodstream in mice with mucopolysaccharidosis types IVA and VII, and are retained longer in bone, with substantial residual enzyme activity.

[0006] WO 2011 / 000958 describes synthetic isosteric analogues of mannose 6-phosphate (M6P) with an affinity for RM6P-CI ranging from 10' 4 at 10' 9M. These M6P analogs, called "AMFA" ("Synthetic Analogues of Mannose 6-phosphate Functionalized in Anomer Position") were designed to be selectively grafted, via a spacer arm, onto glycoproteins, and more specifically onto the oligosaccharide chains of a lysosomal enzyme. This grafting preserves both the three-dimensional structure of the enzyme and its enzymatic activity. In addition, the bifunctional compounds resulting from this grafting exhibit good stability in the blood. In El Cheikh, K. et al (Angew. Chem. Int. Ed. 2016, 55,14774-14777), an AMFA compound comprising a phosphonate end was grafted onto the acid alpha-glucosidase (GAA) enzyme via a spacer arm for the treatment of Pompe disease, which is a lysosomal storage disease primarily affecting muscles.However, these compounds, even if they prove interesting for the treatment of lysosomal storage diseases, do not allow specific treatment of alterations in bone tissue.

[0007] The inventors have now developed new conjugates comprising isostere analogues of mannose 6-phosphate (M6P) with particularly advantageous properties. The term “isostere of M6P” means a synthetic chemical compound having the same biological activity as M6P but with improved stability. The conjugates of the invention more particularly comprise M6P analogs which exhibit both an affinity for the cation-independent mannose 6-phosphate receptor (CM6P-CI) and also for bone tissue, and in particular for hydroxyapatite. In addition, 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): [Cheml] in which: X represents a bisphosphonate group [Chem2] a hydroxybisphosphonate group [Chem3] a halobisphosphonate group [Chem4] with T representing a halogen Cl or F, a malonate group [Chem5] a phosphonoacetate group [Chem6] with Z representing independently of each other H; an alkali metal chosen from Na, Li or K; an ammonium NF; n is an integer ranging from 0 to 2; Li represents a radical chosen from the group comprising *-ON=**, [Chem7] 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 chosen from the group comprising proteins, in particular antibodies and lysosomal enzymes, nanoparticles, cytotoxic compounds and markers for medical imaging, Yi forming covalent bond(s) with Li.

[0009] According to a second aspect, the present invention relates to a process for preparing a conjugate of formula (I) as defined above.

[0010] According to a third aspect, the present invention relates to a conjugate of formula (I) for medical use, of a diagnostic or therapeutic type. It relates in particular to a conjugate of formula (I) for use as a medicament in the treatment of bone pathologies and / or pathologies affecting both bone tissue and soft tissues. Brief description of the drawings

[0011] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which: Fig. 1

[0012] [Fig. 1] illustrates the process for the preparation of the triflate intermediate 6: 2-bromoethyl 2,3,4-tri-O-benzoyl-6-(trifluoromethanesulfonate)-aD-mannopyranoside, which will serve as a precursor for the synthesis of the compounds of formula (II) called MAM-1 or 11 and MAM-2 or 14, respectively. Fig. 2

[0013] [Fig. 2] illustrates the process for 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 precursor 6. Fig. 3

[0014] [Fig. 3] illustrates the process for preparing the compound of formula (II), designated MAM-2 or 14, in which X represents a malonate group with Z = H, n is equal to zero and L represents ONH2, from precursor 6. Fig. 4

[0015] [Fig. 4] illustrates the general synthesis scheme of conjugates of formula (I) in which is equal to 1, depending on the meaning of the reactive chemical group L of the M6P analogue of general formula (II). Figure 4 point 1 / illustrates the reaction between the oxy-amine function of the M6P analogue of formula (II) with an aldehyde function (-CHO) (previously generated during an oxidative process) of a product of interest Y (such as an antibody or a lysosomal enzyme). The product Y is represented by Yi'-CHO, Y1' representing the product Y without its functional group L' equal to -CHO. The analogue (II) is called 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 21 illustrates the reaction between the squarate function of the M6P analogue of formula (II) with an amine function (-NH2) of a product of interest Y. The product of interest Y is represented by Yi'-NH2, Y1' representing Y without its functional group L' equal to -NH2. Figure 4 point 3 / illustrates the reaction between the maleimide function of the M6P analogue of formula (II) with a thiol function (-SH) of a product of interest Y. The product of interest Y is represented by Yi'-SH, Y1' representing Y without its functional group L' equal to -SH. Figure 4 point 4 / illustrates the reaction between the carbonylacrylic function of the M6P analogue of formula (II) with a thiol function of a product of interest Y.

[0016] [Fig. 5] illustrates the cytotoxicity on healthy fibroblasts of the compounds of formula (II) MAM-1 and MAM-2 in comparison with the compound mannose 6-phosphate (M6P) and with an analogous compound of M6P, namely the compound called "AMFA", a compound whose formula is close to that of a compound of formula (II), namely with n equal to zero and L equal to ONH2 but with X which represents a phosphonate group -CH2- P(O)(OH)2. The x-axis represents the molar concentration of the compounds M6P (black histogram), AMFA (grey 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

[0017] [Fig. 6] illustrates the interactions between RM6P-CI and compounds of formula (II) MAM-1 and MAM-2 in comparison with compounds M6P and AMFA. The x-axis represents the molar concentration of compounds M6P (dotted curve), AMFA (grey curve with square patterns), MAM-1 (black curve with round patterns) and MAM-2 (light grey curve with a cross). The y-axis represents the percentage of binding of said compounds to RM6P-CI. Fig. 7

[0018] [Fig. 7] illustrates the adsorption to hydroxyapatite (HA) of the compounds of formula (II) MAM-1 and MAM-2 and of the compounds M6P, AMFA, zoledronate and medronic acid. The x-axis represents, respectively from left to right: M6P (black histogram), AMFA (white histogram), MAM-1 (dark grey histogram), MAM-2 (hatched histogram), zoledronate (dotted histogram) and medronic acid (light grey histogram). The y-axis represents the percentage of compounds adsorbed to HA. Fig. 8

[0019] [Fig. 8] illustrates the cytotoxicity on healthy fibroblasts of the conjugates of the invention of formula (I), namely Myo-MAM-1 and Myo-MAM-2, in comparison with the Myo-AMFA conjugate and with the commercial Myozyme ® enzyme alone (which is the alpha-alglucosidase enzyme). The x-axis represents the molar concentration of the compounds Myozyme ® (black histogram), Myo-AMFA (grey histogram), Myo-MAM-1 (white histogram) and Myo-MAM-2 (hatched histogram). The y-axis represents the 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

[0020] [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 (grey curve with square pattern), Infliximab-AMFA (grey curve with triangle pattern), Infliximab-MAM-1 (black curve with cross pattern) and Infliximab-MAM-2 (light grey curve with asterisk pattern). The y-axis in each of these figures represents the percentage binding of the compounds to RM6P-CI. Fig. 10

[0021] [Fig. 10] illustrates the adsorption to hydroxyapatite (HA) of the antibody Infliximab alone or coupled to the compounds of formula (II) MAM-1 and MAM-2 or to AMFA. The x-axis represents, respectively 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 to HA. Detailed description

[0022] Conjugates of formula (I)

[0023] As indicated, the subject of the present invention is a conjugate of formula (I) as defined above. For the purposes of the invention, the term "conjugate" means a compound comprising two parts linked together by a covalent bond. The first part of the conjugate represents at least one M6P analogue while the second part of the conjugate Yi represents a product of interest Y selected from the group comprising proteins (such as antibodies, lysosomal enzymes etc.), nanoparticles, cytotoxic compounds and markers for medical imaging. The product of interest Y denotes the “free” product of interest when it does not form a bond 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 Li 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, Y / 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 M6P analogue in order to form a covalent bond between the product of interest Y and the M6P analogue and thus obtain the conjugate of formula (I) of the invention. In the present application, the terms “functional group”, “reactive function” or “reactive chemical group” may be used interchangeably. Each of these terms denotes a group carried by the product of interest Y (or carried by the M6P analogue) capable of reacting with a group carried by the M6P analogue (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 indicates the number of M6P analogue(s) linked to the product of interest Yi. According to the invention, M6P analogue(s) may be covalently linked to a product of interest. These M6P analogues are linked to the product of interest via the Li radical. An M6P analogue is understood to mean a compound that differs from natural M6P but exhibits a high interaction capacity with RM6P-CI. An “interaction” in the present application means a non-covalent type bond. Throughout the application, M6P denotes mannose 6-phosphate and RM6P-CI denotes cation-independent mannose 6-phosphate receptor. RM6P-CI is a ubiquitous receptor that is present both in the cytoplasm and on the membrane of cells. Its role is in particular to internalize by endocytosis into the cell molecules carrying the recognition marker mannose 6-phosphate (M6P). The conjugate of formula (I) of the invention is particularly advantageous in that it has several interaction capacities with several targets such as RM6P-CI, bone tissue or even a molecule of therapeutic interest. Thus, the conjugate (I) of the invention more particularly has a capacity for interaction with RM6P-CI (via the M6P analogue), a capacity for interaction at the level of bone tissue, more particularly at the level of HA (via the M6P analogue and more particularly the X group), but also a capacity for interaction with molecules of therapeutic interest via the compound of interest Yi. Thus, if the compound of interest Yi is an antibody, then said antibody may interact, for example, with a molecule of therapeutic interest which would be a target antigen. 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 involved in a pathological disorder. Examples of molecules of therapeutic interest interacting with compounds of interest Yi include glycosaminoglycans which accumulate and create lysosomal storage diseases such as mucopolysaccharidoses, growth factors or membrane proteins involved in the growth of cancers, and in particular primary bone cancers or cancerous metastases in bone tissue, factors involved in bone pathologies and which can be used in imaging for the diagnosis or therapeutic targeting of osteoporosis or bone metastases from breast, kidney, prostate, thyroid and lung cancers. Bone tissue refers to connective tissue that is metabolically active and consists 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 term "interaction capacity" of the conjugate (I) means its capacity to form non-covalent interactions with the above-mentioned targets, namely with: - the RM6P-CI via the M6P analogue, - HA of bone tissue via the X group of the M6P analogue, - a molecule of therapeutic interest via the compound of interest Yi. The ability of the conjugate to interact with its targets can also be referred to as the affinity of the conjugate with its targets. Affinity refers 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-type 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.

[0024] In the conjugate of formula (I) as defined above, Yi can more particularly be represented by the group L2-Y'I in which Y'i 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 Y1 thus being able to be represented by =CH-Y'i, -NH-Y'1 and -S-Y'i. The radical L2 is more particularly derived from the transformation of the functional group L' carried by the product of interest Y1 when the latter forms a covalent bond with the analogue of M6P.

[0025] According to an advantageous embodiment of the invention, the conjugate of formula (I) is characterized in that is an integer equal to 1, and in that said conjugate is chosen from the group comprising: [Chem10] with X, n and Y'i as defined above.

[0026] 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 domain of interaction with the antigen, or a lysosomal enzyme Y.

[0027] According to one embodiment of the invention, the conjugate (I) is characterized in that Yi represents an antibody Y chosen from the group comprising monoclonal antibodies, chimeric antibodies, human or humanized antibodies, chain antibodies heavy and light, single-chain antibodies, bispecific or multispecific antibodies and nanobodies.

[0028] According to 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 type IgG, in particular of subtype IgG1, IgG2, IgG3 or IgG4, or an immunoglobulin of type IgE, IgD, IgA or IgM.

[0029] 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 mucopolysaccharidoses for which bone growth is altered.

[0030] 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), with respect to the mannose 6-phosphate cation independent receptor (RM6P-CI) ranging from 10' 4 M to 10' 9 M, and preferably ranging from I O' 5 M to IO' 8 Mr.

[0031] 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 the hydroxyapatite present in the bone tissue.

[0032] The property of double interaction capacity of the conjugates (I) of the invention, namely at the level of RM6P-CI (and therefore at the level of the endo-lysosomal compartments of the cell) and at the level of the bone tissue is notably due to the judicious choice of the X group of the conjugate of formula (I). Furthermore, the conjugates of the invention are also very advantageous due to the structure of their spacer arm. The term "spacer arm" means the part located after the oxygen carried by the anomeric carbon of the cyclic structure of the M6P analogue, which forms the junction with the product of interest Y1, namely the part "-(CH2)2(O-CH2-CH2)n-Li-" (see conjugate of formula (I)). The structure of this spacer arm is particularly simple from a chemical point of view and allows efficient grafting with the product of interest. Products of interest Y1 considered alone and / or molecules of therapeutic interest interacting with these products of interest Y1 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 diagnosis and therapy, and in particular in enzyme replacement therapies combined with a bone targeting strategy for the treatment of lysosomal storage diseases in the human body or in animals. These conjugates can also find applications in the field of treatment of bone cancers or osteoporosis.

[0033] Process for the preparation of conjugates of formula (I)

[0034] According to another aspect, the present invention relates to a process for preparing a conjugate of formula (I) as defined above, characterized in that the following are reacted: - a product of interest Y with - nor compound(s) corresponding to the following general formula (II) [Chem14] in which X, n and are as defined above, L is a reactive chemical group selected from the group consisting of -O-NH2, [Chem 15] [Chem 17] said group L of compound (II) forming covalent bond(s) with functional group(s) carried by said product of interest Y.

[0035] 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 radical L2 previously mentioned in relation to Y1 (namely Y1 is represented by the group L2-Y'I) is more particularly derived from the transformation of the functional group L' carried by the product of interest Y (Y being represented by the group L'-Y'i,) when Y forms a covalent bond with the analogue of M6P and is then represented by Y1. Compounds of formula (II) are particularly interesting because of the simplicity of their spacer arm. The term "spacer arm" refers to the part located after the oxygen carried by the anomeric carbon of the cyclic structure of the M6P analogue and which includes the reactive chemical group L, namely the part (CH2)2(O-CH2-CH2)nL. Indeed, the simplicity of the structure of the spacer arm contributes to the advantages presented by the conjugates of formula (I) of the invention. This simplicity of the spacer arm makes it possible in particular to easily synthesize the compounds of formula (II) and then to carry out 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.

[0036] The L groups of the M6P analogue as defined above (in order of appearance) can be respectively referred to in a simplified manner as "oxy-amine", "squarate", "maleimide" and "group comprising a carbonylacrylic function".

[0037] M6P analogues of formula (II) can be represented by the acronym "MAM", the acronym MAM meaning "medronic acid mimic".

[0038] According to one embodiment of the invention, the analogues of M6P of formula (II) will be chosen from table 1 below.

[0039] [Table 1]

[0040] According to an advantageous embodiment of the method 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 effective coupling with a product of interest Y and on the other hand makes it possible to interact effectively both with the RM6P-CI and with the bone tissue.

[0041] According to another particularly advantageous embodiment, the analogues of formula (II) are those in which the L group is an “oxy-amine” or a “squarate”.

[0042] According to a particularly advantageous embodiment of the invention, if Y represents for example an antibody or a lysosomal enzyme, the L group of the 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 of the lysosomal enzyme. The glycosidic part of the antibody mentioned above is more specifically that located at the level of the Fc region of the antibody. As an example of the L group of compound (II), we can cite the oxy-amine group.

[0043] According to another embodiment of the invention, the L group of compound (II) will bind at an appropriate amino acid residue of the peptide chain / part of the antibody or lysosomal enzyme. Examples of suitable amino acid residues include an amine group from lysine or a thiol group from cysteine. Examples of the L group of compound (II) include a squarate group, a maleimide group or a carbonylacrylic group.

[0044] 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 Figure 4, point 1 / , the carbonyl function (-CHO) of the product of interest Y reacts with the oxy-amine function of the compound of formula (II). If Y represents an antibody, this coupling mode occurs for example at the level of an oligosaccharide chain of the glycosidic part located on the Fc part of the antibody. Concerning the coupling mode of the compound of formula (II) comprising the squarate group (see figure 4 point 2 / ), if Y represents an antibody, the latter intervenes 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. Concerning the mode of coupling of the compound of formula (II) with a maleimide group (see figure 4 point 3 / ), if Y represents an antibody, the latter intervenes at the level of a cysteine ​​residue of the peptide part of the antibody, namely more particularly at the level of the thiol function. Concerning the coupling mode of the compound of formula (II) comprising a carbonylacrylic function (see figure 4 point 4 / ), if Y represents an antibody, the latter intervenes 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 at the level of the other reactive functions of the antibody (such as for example the FcRn receptors of the antibody), which advantageously allows the antibody to preserve its natural properties. An antibody has been specifically cited 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.

[0045] Use of conjugates (I) in a method of therapeutic or diagnostic treatment

[0046] For the reasons mentioned above, the conjugates (I) of the invention, due to their advantageous properties, are particularly interesting for use in the field of therapy or in the field of diagnosis.

[0047] According to another aspect of the invention, there is provided a pharmaceutical composition 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" means a dosage sufficient to produce a desired result, for example, an amount sufficient to achieve beneficial or desired therapeutic (including preventive) results, such as a reduction in the level of an element whose extracellular or membrane overexpression is responsible for a pathology or is involved in a pathological condition. An effective amount may require one or more administrations.

[0048] According to yet another aspect, the invention relates to a pharmaceutical composition comprising: - a therapeutically effective amount of the conjugate of formula (I), - at least one other therapeutically active agent, - possibly at least one pharmaceutically acceptable excipient.

[0049] 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.

[0050] In this regard, the invention more particularly relates to a conjugate of formula (I) as defined above or a pharmaceutical composition as defined above, for use as a medicament in the treatment of bone pathologies and / or pathologies affecting both bone tissue and soft tissues. Examples of bone pathology include: - osteoporosis and osteomalacia, bone dystrophies (such as Paget's disease of the bone), osteonecrosis, benign bone tumors (osteomas, osteoblastomas, etc.), benign cartilage tumors (enchondromas, osteochondromas, etc.), certain forms of arthritis (including osteoarthritis), - certain primary bone tumors which originate in a bone. Some primary bone tumors are malignant, such as adamantinomas and osteosarcomas occurring 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's sarcoma, fibrosarcomas and lymphomas undifferentiated bone tissue with a soft tissue component from the moment of formation, - 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.), - a cancer developed from the bone marrow such as multiple myeloma, - lysosomal storage diseases such as mucopolysaccharidoses (MPS-I, MPS-I I, MPS-I II, MPS-IV, MPS-V, MPS-VI and MPS-VII), Fabry disease and Pompe disease.

[0051] According to an advantageous embodiment of the invention, the conjugate or the pharmaceutical composition is suitable for use in the treatment of a pathology chosen from the group comprising osteoporosis, bone cancer, lysosomal storage disease.

[0052] 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.

[0053] According to an advantageous embodiment, the subject of the invention is 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

[0054] 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 called AMFA (compound notably described in WO 2011 / 000958) and to the mannose 6-phosphate compound M6P.

[0055] Example 1: Synthesis of M6P analogues

[0056] The M6P analogues synthesized in this example are the compounds of formula (II) called respectively MAM-1 or 11 and MAM-2 or 14 whose developed formulas are respectively as follows: [Chem18]

[0057] 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-(trifluoromethanesulfonyl)-aD-2-bromoethyl mannopyranoside”) is illustrated in Figure 1. The starting compound is 1,2,3,4,6-penta-O-acetyl aD-mannose to which a bromoethoxy group is introduced in the anomeric position using boron trifluoride diethyl etherate and 2-bromoethanol in dichloromethane to form compound 1 (“2,3,4,6-tetra-O-acetyl- aD-2-bromoethyl mannopyranoside”) in 80% yield. The acetates present at positions 2, 3, 4 and 6 of compound 1 were then methanolyzed in the presence of sodium methanolate solution in methanol to form compound 2 (“2-bromoethyl aD-mannopyranoside”) in 100% yield. The 6-position of derivative 2 is then protected with monomethoxytrityl chloride in pyridine to give intermediate 3 (“2-bromoethyl 6-O-methoxytrityl aD-mannopyranoside”).Successively, positions 2, 3 and 4 are then benzoylated by the action of benzoyl bromide to form compound 4 (“2,3,4-tri-O-benzoyl-6-O-((4-methoxyphenyl)diphenylmethyl))-aD-mannopyranoside de 2-bromoethyl”). Synthon 5 (“2,3,4-tri-O-benzoyl-aD-mannopyranoside de 2-bromoethyl”) is obtained after selective deprotection of the trityl group in the presence of cerium ammonium nitrate (CAN) in an acetonitrile / water mixture, at reflux. The yield over 3 steps is 45%. Position 6 of compound 5 is then activated in the form of triflate, thanks to the cold addition of triflic anhydride on the sugar in the presence of 2,6-di-ferf-butyl-4-methylpyridine. Compound 6 is thus obtained with a yield of 90% after purification. Conditions and reagents: (i) BF3.Et2O, 2-Bromoethanol, DCM, TA, 20 h; (ii) MeONa, MeOH, TA, 1 h; (iii) MMTrCI, Pyridine, TA, 5 h; (iv) BzCI, Pyridine, 0°C, 19h; (v) CAN, ACN / H2O (95:5), 82°C, 2 h; (vi) Tf20, 2,6-Di-ferf-butyl-4-methylpyridine, DCM, -40°C, 30 min.

[0058] Preparation of the “bisphosphonate” compound MAM-1 (or 11) corresponding to the formula (11) The compound MAM-1 (or 11) corresponds to the formula (II) in which X represents a bisphosphonate group with Z = H, n is equal to zero and L represents ONH2, from the precursor 6. This compound can be called the “bisphosphonate” compound MAM-1. The synthesis of compound MAM-1 (or 11) is illustrated in Figure 2. The triflate synthon 6 is transformed into bisphosphonate intermediate 7 (“2,3,4-tri-O-benzoyl-6-deoxy-6-bis(diethoxyphosphinyl)methylene-aD-mannopyranoside de 2-bromoéthyle”) by cold addition of a solution of tetraethyl methylenebisphosphonate anion prepared in a suspension of sodium hydride (NaH) in tetrahydrofuran (THF). The yield of this step is 50%. Intermediate 8 (“6-deoxy-6-bis(diethoxyphosphinyl)methylene-aD-mannopyranoside de 2-bromoéthyle”) is obtained after methanolysis of the benzoate groups thanks to the action of a methanolic solution of sodium methanolate, with a yield of 50%. Compound 9 (“6-deoxy-6-bis(diethoxyphosphinyl)methylene-aD-mannopyranoside de 2-(phtalimidoxy)ethyl”) is obtained in 55% yield after nucleophilic substitution of bromine by the anion of A / -hydroxyphthalimide formed with NaH in hot THF.Silylation of positions 2, 3 and 4 of the intermediate is achieved by adding trimethylsilyl chloride and triethylamine in dichloromethane, to obtain derivative 10 (“2,3,4-tri-O-trimethylsilyl-6-deoxy-6-bis(diethoxyphosphinyl)methylene-aD-2-(phthalimidoxy)ethyl mannopyranoside”) in quantitative yield. The final product MAM-1 (or 11) (“2-aminooxyethyl 6-deoxy-6-bis(dihydroxyphosphinyl)methylene-aD-2-aminooxyethyl mannopyranoside”) is obtained following two successive deprotection reactions. First, the alkyl groups of the bisphosphonate are converted by transesterification to the corresponding trimethylsilyl esters using the Rabinowitz reaction using trimethylsilyl chloride TMSCI in the presence of sodium iodide NaI 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) / V-Hydroxyphthalimide, DBU, THF, 60°C, 4 h; (iv) TMSCI, Et3N, DCM, 0°C, 20 min; (v) TMSCI, Nal, Et3N, ACN, 50°C, 24 h; (vi) N2H4.H2O, MeOH, TA, 24 h.

[0059] Preparation of the “malonate” compound MAM-2 (or 14) corresponding to the formula (II) The compound MAM-2 (or 14) corresponds to the formula (II) in which X represents a malonate group with Z = H, n is equal to zero and L represents ONH2, from the precursor 6. This compound can be called the “malonate” compound MAM-2. The synthesis of compound MAM-2 (or 14) is illustrated in Figure 3. Triflate 6 is transformed into compound 12 (“methyl (2,3,4-tri-O-benzoyl-6,7-dideoxy-7-methoxycarbonyl-aD-manno-octopyranoside de 2-bromoethyl) uronate”) with a yield of 85% after reaction with the anion of dimethyl malonate previously prepared by the action of NaH in THF. The bromine atom of compound 12 is then substituted by the anion of A / -hydroxyphthalimide prepared with sodium bicarbonate NaHCOs in DMF, at 65°C. Compound 13 (“methyl 2,3,4-tri-O-benzoyl-6,7-dideoxy-7-methoxycarbonyl-aD-manno-octopyranoside de 2-(phthalimidoxy)ethyl) uronate”) is thus obtained with a yield of 92%. Compound 13 is then treated with hydrazine monohydrate in MeOH, followed by 1 M NaOH in THF to produce the final compound MAM-2 (or 14) (“2-aminooxyethyl (6,7-dideoxy-7-carboxy-aD-manno-octopyranoside)uronic acid”) in 42% yield over the 2 steps. Conditions and reagents: (i) Dimethyl malonate, NaHCOs, THF, 0°C, 5 h; (ii) N-hydroxyphthalimide, DBU, DMF, 65°C, 22 h; (iii) N2H4.H2O, MeOH, 0°C, 2h30; (iv) 1 M NaOH, THF, 0°C, 2h30

[0060] Preparation of AMFA compound The compounds MAM-1 and MAM-2 will be compared in particular in the following to another analogue of M6P, namely the compound called AMFA whose developed formula is as follows: [Chem20] This AMFA compound is synthesized according to a protocol described in document WO 2011 / 000958. The compounds MAM-1 and MAM-2 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).

[0061] Example 2: Preparation of the conjugates of the invention

[0062] Two products of interest Y, namely a lysosomal enzyme and an antibody, were respectively functionalized with M6P analogues, namely with the compounds of formula (II) of the invention MAM-1 and MAM-2, but also with the AMFA compound.

[0063] The lysosomal enzyme tested is commercially available under the name Myozyme ®. It is the enzyme alpha alglucosidase (or acid alpha glucosidase). It can be represented in the following as "Myo". It contains M6P residues in its structure allowing the targeting of RM6P-CI. The lysosomal enzyme Myo is used for the treatment of Pompe disease by enzyme replacement therapy. The antibody tested is infliximab, which is a chimeric monoclonal antibody of the IgG1 type that does not have M6P residues in its structure. It can be represented in the following as "Infli".

[0064] The conjugates thus formed may indifferently be represented in the present application by “MAM-1 -Myo” or “Myo-MAM-1”, “MAM-2-Myo” or “Myo-MAM-2”, “MAM-1 -Infli” or “lnfli-MAM-1”, “MAM-2-lnfli” or “lnfli-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 part. Advantageously according to the invention the MAM-1 or MAM-2 part of the conjugate (I) interacts both with RM6P-CI and with hydroxyapatite (HA).

[0065] Coupling and quantification of M6P analogues (MAM-1, 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 thanks to the ethyloxyamine function present on the spacer arm of MAM-1, MAM-2 and AMFA, which allows the formation of a covalent bond of the oxime type 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 figure 4 point 1 / . Oxidation of oligosaccharide chains of the product of interest Y (Myo or Infliximab) An amount of 0.5 mg / mL of product of interest Y and a 1 mM solution of metaperiodate sodium (NaIC ) 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 Myo or Infliximab After the gentle oxidation step, an excess of M6P analogue (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 MALDITOF mass spectrometry or in a buffer containing 25 mM phosphate, 2% mannitol and 0.005% polysorbate 80 overnight. MALDI-TOF mass spectrometry analysis made it possible to evaluate the number of “M6P analogue” residues grafted onto the product of interest Y. Table 2 below represents the average number of grafted M6P analogues, calculated from two MALDI-TOF analyses.

[0066] [Table 2]

[0067] Remarks and conclusion Under this condition of oxidation by 1 mM NaI04 the grafting of AMFA, MAM-1 and MAM-2 is estimated at 3.9 to 4.8 M6P analogues per molecule of Infliximab and only 0.9 to 1.1 M6P analogues 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.

[0068] Example 3: Biological evaluation of M6P analogues The M6P analogues of formula (II) of the invention, namely the compounds MAM-1 and MAM-2, were biologically compared to the AMFA analogue and to M6P. Indeed, the AMFA and M6P compounds are known not to exhibit cellular toxicity and to have interaction capacities with RM6P-CI.

[0069] 1 / Evaluation of the cytotoxicity of MAM-1 and MAM-2 analogues The cytotoxicity of MAM-1 and MAM-2 analogues of formula (II) was evaluated in comparison with that of M6P and the AMFA analogue on healthy human fibroblasts according to the protocol described below. Experimental protocol: The cells are seeded in 96-well plates (Maxisorp Nunc) in an incubator at 37°C containing 5% CO2. They are then treated according to a concentration gradient (10' 3 at 10' 6 M) of analogues. 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 solution (1:1). Cell survival is measured using a spectrophotometer at 540 nm. The results obtained are illustrated in Figure 5. It is clear from this figure that the compounds MAM-1, MAM-2, AMFA and M6P are not cytotoxic on the two cell lines even at high concentrations.

[0070] 2 / Affinity of MAM-1 and MAM-2 analogues for RM6P-CI MAM-1 and MAM-2 analogues were evaluated for their affinity for the RM6P-CI receptor in comparison with AMFA and M6P. As already mentioned, affinity refers to the intensity of interaction of M6P analogues with RM6P-CI. To do this, a test based on interaction competition with RM6P-CI is performed according to the protocol described below. Experimental protocol: 96-well plates (Maxisorp Nunc) are incubated overnight at 4°C with 200 pL of PM6P (pentamannose 6-phosphate) at a concentration of 200 pg.mL' 1, in carbonate buffer (0.1 M NaHCO3 / Na2CC>3, pH 9.6). The next day, the solution containing residual PM6P is discarded and the wells are saturated, for 1 h at room temperature, with 360 μL 1% gelatin (Type A from Porcine Skin) diluted in PBS (1.9 mM NaF^PC, 8.1 mM Na2PC>4 and 154 mM NaCl, pH 7.4). The wells are then rinsed 5 times with PBS supplemented with 0.2% gelatin. All washes and dilutions are carried out in PBS supplemented with 0.2% gelatin. The compounds to be tested (MAM-1, MAM-2, AMFA and M6P) at the different concentrations (from 10' 3 at 10' 6 M) are pre-incubated in the presence of previously biotinylated RM6P-Cl (RM6Pb) (2.5 pg.mL' 1 ) for 20 min, then 200 pL of the mixture is incubated in the wells for 2 h, at room temperature. After 3 washes, the wells are incubated for 1 h with a 3.10' solution 8 M of streptavidin-peroxidase. After 3 further washes, 200 pL of solution containing 1 mg.mL' 1OPD (o-phenylenediamine and 1 pL 30% H2O2.mL' 1 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 Figure 6. The data indicate very good affinities of MAM-1, MAM-2 and AMFA corresponding to 50% inhibitory concentrations (IC50) of 3.2.10' 5 M, 3.0.10' 5 M, 4.5.10' 5 M respectively. By comparison, the affinity of M6P is 2.4.10' 5 M in these same experiences.

[0071] 3 / Adsorption of MAM-1 and MAM-2 analogues on hydroxyapatite The method is based on the inverse determination of the quantity of analogues not bound to hydroxyapatite, by NMR analysis 31 P or 1H. For this, two tubes are prepared containing an equal amount of analogues. In one, a defined amount of hydroxyapatite is introduced beforehand and the two tubes are then placed under agitation. After centrifugation, an equal volume of the supernatant of each tube is removed and a defined amount of standards is added as a complement during conditioning for NMR analysis. For each tube, the area of ​​the signals corresponding to the analogues and that of the standard are measured and the ratio of the two areas is calculated. The adsorption capacity of the analogues MAM-1, MAM-2, AMFA and M6P is evaluated according to this method and compared with those of commercial therapeutic compounds used in the treatment of bone diseases, namely zoledronate and medronic acid. The results obtained are illustrated in Figure 7. It is clear from this figure that the MAM-1 analogue binds completely to hydroxyapatite like the therapeutic bisphosphonate derivatives of the prior art (zoledronate and medronic acid). These results are therefore encouraging and promising as to the ability of the conjugates of the invention comprising such M6P analogues to effectively treat bone pathologies. Indeed, even if bisphosphonate derivatives have previously been used for the treatment of bone pathologies, nothing suggested to the person skilled in the art that an M6P analogue of formula (II) with a group X as previously defined would make it possible to confer a double interaction capacity, both at the level of RM6P-CI but also at the level of HA. The compounds M6P, AMFA and MAM-2, for their part, demonstrate an adsorption capacity for HA that is significantly lower than the bisphosphonate derivatives, with a value close to 30% for MAM-2.

[0072] Example 4: Biological evaluation of the conjugates of the invention

[0073] The conjugates tested in this example are those previously described in Table 2.

[0074] 1 / Evaluation of the cytotoxicity of Myo-MAM-1 and Myo-MAM-2 conjugates The cytotoxicity of the Myo-MAM-1, Myo-MAM-2 conjugates of the invention of formula (I) and the Myo-AMFA conjugate was evaluated in comparison with the lysosomal enzyme Myo alone. on healthy human fibroblasts, according to the same protocol as 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 Figure 8. The Myo-MAM-1, Myo-MAM-2 and Myo-AMFA conjugates show their safety on human fibroblasts.

[0075] 2 / Affinity of lnfli-MAM-1 and lnfli-MAM-2 conjugates for RM6P-CI The conjugates lnfli-MAM-1 and lnfli-MAM-2 of the invention of formula (I) and the conjugate Infli- AMFA 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 Figure 9. It is interesting to note that the grafting of the MAM-1 and MAM-2 analogues of the invention and the AMFA analogue to Infliximab makes it possible to obtain an antibody with affinity for RM6P-CI while infliximab does not have any affinity, in accordance 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 the interaction with RM6P-CI, which indicates that the addition of several bispecific analogues of the MAM-1 or MAM-2 type advantageously makes it possible to create an affinity 10 times higher than that of M6P.

[0076] 3 / Adsorption of lnfli-MAM-1, lnfli-MAM-2 conjugates on hydroxyapatite The conjugates lnfli-MAM-1, lnfli-MAM-2 of the invention of formula (I) and the conjugate Infli- AMFA 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 Figure 10. The results demonstrate that approximately 28% of infliximab is naturally adsorbed to hydroxyapatite (HA). Grafting MAM-1 and MAM-2 analogues to the antibody significantly increases adsorption to HA. 4.6 MAM-1 and 3.9 MAM-2 grafted to infliximab increase infliximab adsorption to HA by 20% and 25%, respectively. The equivalent adsorptions of lnfli-MAM-1 and lnfli-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 figure 7). It is also interesting to note that grafting the AMFA analogue to the antibody does not in any way increase the adsorption of infliximab to HA but on the contrary has the effect of reducing it. This demonstrates once again the interest of the analogues (II) of the invention which confer particularly advantageous properties on the conjugates (I) of the invention.

[0077] This disclosure is not limited to the examples described above, solely by way of example, but it encompasses all the variations that a person skilled in the art may envisage within the framework of the protection sought. List of cited documents Patent documents

[0078] For convenience, the following patent documents are cited: - patcitl: WO 2011 / 000958. Non-patent literature

[0079] For convenience, the following non-patent material is cited: - nplcitl: Tomatsu, S. et al., Mol. Gen. Metab. 2015, 114, 94-109; - nplcite2: El Cheikh, K. et al Angew. Chem. Int. Ed. 2016, 55,14774-14777.

Claims

Claims

1. Conjugate characterized in that it has the following general formula (I): [Cheml] in which: X represents a bisphosphonate group [Chem2] a halobisphosphonate group with T representing a halogen Cl or F, a malonate group [Chem5] a phosphonoacetate group [Chem6] with Z representing independently of each other H; an alkali metal chosen from Na, Li or K; an ammonium NF; n is an integer ranging from 0 to 2; Li represents a radical chosen from the group comprising *-ON=**, [Chem7] [Chem8] [Chem9] 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 chosen from the group comprising proteins, in particular antibodies and lysosomal enzymes, nanoparticles, cytotoxic compounds and markers for medical imaging, Yi forming covalent bond(s) with Li.

2. Conjugate according to claim 1, characterized in that Yi is represented by the group l_2-Y'i in which Y'i represents the product of interest Y linked to Li via the radical l_2 with l_2 chosen from the group comprising =CH-, -NH- and -S-, said Yi thus being able to be represented by =CH-Y'i, -NH-Y'i and -S-Y'i.

3. Conjugate according to claim 1 or 2, characterized in that is an integer equal to 1 and in that said conjugate of formula (I) is chosen from the group comprising: [Chem10] [Chem12] with X, n and Y'i as defined in claim 1 or 2.

4. Conjugate 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 domain of interaction with the antigen, or a lysosomal enzyme Y.

5. Conjugate according to claim 4, characterized in that Yi represents an antibody Y which is an immunoglobulin of type IgG, in particular of subtype IgG 1, IgG2, IgG3 or IgG4, or an immunoglobulin of type IgE, IgD, IgA or IgM.

6. Conjugate 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 altered.

7. Conjugate according to any one of claims 1 to 6, characterized in that it has an affinity, measured by the 50% inhibiting concentration (IC50), with respect to the mannose 6-phosphate cation-independent receptor (RM6P-CI) ranging from 10' 4 M to 10' 9 M, and preferably ranging from 10' 5 M to 10' 8 Mr.

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

9. Process for the preparation of a conjugate of formula (I) as defined in any one of claims 1 to 8, characterized in that the following are reacted: - a product of interest Y with - nor compound(s) corresponding to the general formula (II) [Chem14] in which X, n and are as defined in claim 1, L is a reactive chemical group selected from the group consisting of -O-NH2, [Chem15] [Chem16] And [Chem17] said group L of compound (II) forming covalent bond(s) with 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. Conjugate as defined in any one of claims 1 to 8 or pharmaceutical composition according to claim 10, for use as a medicament in the treatment of bone pathologies and / or pathologies affecting both bone tissue and soft tissues.

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

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

14. A 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 parenteral, intravenous or subcutaneous administration.

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