Non-degradable embolic microspheres

Abstract

The present invention relates to non-biodegradable embolic microspheres comprising a crosslinked matrix based on at least: a) 20% to 95% hydrophilic monomers; b) 1% to 15% non-biodegradable hydrophilic crosslinking monomers; and c) 1.5% to less than 6% of a transfer agent selected from alkyl halides and alicyclic or aliphatic thiols, in particular those having 2 to 24 carbon atoms and, optionally, another functional group selected from amino, hydroxy, and carboxy groups. The present invention further relates to a pharmaceutical composition comprising the non-biodegradable embolic microspheres according to the present invention, advantageously in combination with a pharmaceutically acceptable vehicle intended for parenteral administration. The present invention further relates to a kit comprising a pharmaceutical composition comprising the non-biodegradable embolic microspheres according to the present invention in combination with a pharmaceutically acceptable vehicle intended for parenteral administration, and at least one injection means.

Description

[Technical field]

[0001] The present invention relates to non-biodegradable embolic microspheres comprising a crosslinked polymer matrix, advantageously intended to be injected into an individual and, optionally, for the sustained release of an active substance or macromolecule. [Background technology]

[0002] To prevent blood flow in an area of ​​the body, vascular occlusion therapy (i.e. embolization therapy) is used, which results in ischemia. It may be administered using a catheter that allows the positioning of particulate occlusion agents in the circulatory system. It has various medical applications, such as the treatment of vascular malformations, bleeding processes or tumors, e.g. uterine fibroids, primary or secondary liver tumors. For example, vascular occlusion may cause tumor necrosis, avoiding more invasive surgery. This occlusion technique may also be relevant for the delivery of anticancer drugs in the context of chemoembolization therapy. This allows to increase the local concentration of the drug by targeted injection, as well as its residence time in the tumor. In the case of vascular malformations, vascular occlusion allows the normalization of blood flow to normal tissues, aiding surgery and limiting the risk of bleeding. In bleeding processes, vascular occlusion may result in a decrease in flow rate, facilitating the healing of arterial injuries.

[0003] Commercially available embolic agents for vascular occlusion include embolic solutions (acrylic glues, gels), mechanical devices, and embolic particles. The choice of a specific material depends on many factors, including the type of lesion to be treated, the type of catheter to be used, and the need for temporary or permanent embolic therapy.

[0004] These embolic agents are usually introduced into the blood vessels through catheters, in particular microcatheters, whose diameter is less than that of the blood vessel to be treated. Thus, in the case of solid embolic agents, e.g. particles, their shape allows them to circulate within said catheter and then, once released, to occupy a volume sufficient to cause occlusion of the blood vessel over its entire diameter.

[0005] The shape and size of the embolic agent are factors in the precision of the target area: in the case of particles, it has been found that if they are spherical and of a size suitable for the vessel lumen, they will produce a total embolism and reside exclusively within the target tissue.

[0006] In the prior art, the development of microspheres has been paralleled by the development of increasingly fine microcatheters that have allowed access to more distal arteries. Depending on the size of the microsphere used, the practitioner may advance vascular targeting and perform more or less distal occlusion. Embolization therapy may be set at a selected level. For example, in the case of tumors, blood vessels further destined for the tumor may be more easily occluded, while blood vessels intended for normal tissue may be avoided.

[0007] These microspheres may be biodegradable with the aim of achieving temporary embolization. The main difficulties encountered with these biodegradable microspheres are: -Difficulty in controlling the rate of degradation, which can range from a few hours to several months, depending on the microsphere; - Controlled loss of microspheres without leaving any debris or toxicity to living organisms; and -Difficulty in loading therapeutic agents into these microspheres It is.

[0008] Furthermore, undesired chain transfer reactions within the polymer microspheres can cause irreversible cross-linking, resulting in the formation of non-absorbable polymers.

[0009] Thus, in the applications WO 2012 / 120139 and WO 2012 / 120138 it is described that the addition of a transfer agent to the solution of monomers during the preparation of biodegradable microspheres makes it possible to avoid these undesirable secondary reactions and thus to preserve the degradable properties of the embolic microspheres.

[0010] In contrast to these biodegradable embolic microspheres, which have the advantage of providing temporary embolization, non-biodegradable embolic microspheres allow for permanent embolization.

[0011] Various non-biodegradable microspheres were tested in the 1960s for the purpose of performing embolization therapy (lead, stainless steel, and silicone beads), but the small size of these microspheres and significant reflux in non-target healthy organs increased the level of complications in patients.

[0012] There are non-biodegradable microspheres based on the polymer trisacryl (N-acryloyl-2-amino-2-hydroxymethylpropane-1,3-diol) and gelatine, which may be of porcine origin, such as the product Embosphere® (Biosphere Medical), one of whose drawbacks is the presence of gelatine, which may potentially be of porcine origin.

[0013] Furthermore, non-biodegradable microspheres based on acrylic copolymers and PVA have been proposed for permanent embolization (Osuga et al., (2002) J. Vase Interv Radiol. 13:929-34). These are, for example, the Quadrasphere® microspheres from Biosphere Medical, which are provided in dry form and then mixed with normal saline and / or iodized contrast agent before injection through a catheter and then swell. Their final size after swelling varies as a function of the ionic charge of the medium (2-fold or 4-fold compared to their initial size in saline or contrast agent, respectively). However, their use in embolization therapy is limited by the uncontrolled swelling of the microspheres and the uncontrollable volume of their implantation due to the excessive variation in their final size. In fact, it has been shown that there is a correspondence between the size of the microspheres and the diameter of the occluded vessel. For precise targeting of the vessel to be embolized, it is preferable to use microspheres of the appropriate size (Laurent et al., 2007).

[0014] Therefore, the embolic microspheres must be spherical and calibrated. "Calibrated" means that the microspheres must be classifiable according to their size after swelling. The practitioner then selects microspheres whose size corresponds to the size of the vessel or malformation to be embolized (Laurent et al., 2007). Any morphological defects of these embolic microspheres may cause obstruction of the catheter or have an adverse effect on their embolic properties.

[0015] The resistance to compression and elasticity of the embolic microspheres are also important. In fact, they must retain their shape and their initial size upon release from the microcatheter while being injectable through a microcatheter with a diameter less than their diameter when injected into a blood vessel. Low elasticity and low resistance to compression have been shown to reduce the level of obstruction in vivo (Laurent et al., 2007).

[0016] Young's modulus represents the resistance to compression, or compressibility. It has been shown that the value of Young's modulus of microspheres is directly related to the fact that they are localized in more or less distal sites of the blood vessels into which they are injected (Laurent A., Agents d'embolisation [Embolization agents]. EMC-Radiologie et imagerie medicale-principes et technique-radioprotection 2014;9(1):1-11).

[0017] Microspheres with low compressibility will result in embolism near the injection site, while microspheres with high compressibility will result in embolism distant from the injection site.

[0018] In vitro testing has shown that Embosphere® microspheres from Biosphere Medical are less compressible and result in embolization at the level of the proximal region of the blood vessel into which they are injected. Conversely, Contour SE® microspheres from Boston Scientific are easily deformed and embolize regions of the blood vessel more remote from the injection site.

[0019] One of the problems encountered with microspheres that are too compressible and therefore too deformable is that they may migrate inside the blood vessels under the pressure of the blood flow, which makes their localization uncertain, whereas microspheres that are insufficiently deformable, due to low compressibility, may be difficult to inject or may not return to their initial shape after injection.

[0020] In order to target a specific embolization site, the compressibility of the microspheres must be controlled.

[0021] Furthermore, to be injectable, the microspheres are generally suspended in a mixture of a non-ionic iodized contrast agent and a buffer. For this reason, radiologists generally use a mixture of 50% contrast agent and 50% normal saline, bicarbonate buffer, or phosphate buffer. To ensure their injectability, the microspheres must be uniformly suspended in this 50 / 50 solution. If the microspheres settle or, conversely, float to the surface of the solution, the resulting suspension is inhomogeneous and unstable and therefore cannot be injected into the patient.

[0022] It is therefore advantageous for the microspheres to have a suitable density to allow for homogeneous suspension in a mixture containing 50% contrast agent and 50% normal saline, bicarbonate buffer, phosphate buffer or Tris buffer (tris(hydroxymethyl)aminomethane). Summary of the Invention [Problem to be solved by the invention]

[0023] therefore, is the calibrated size, - Made from biocompatible materials with no risk of allergies and have suitable mechanical properties, in particular swelling, elasticity and compressibility, for injection through a catheter or microcatheter and are capable of returning to their initial shape after injection while avoiding embolization remote from the target site; There is a great need for non-biodegradable embolic microspheres.

[0024] Furthermore, they must be capable of maintaining their mechanical properties whilst being loaded with active substances. [Means for solving the problem]

[0025] The present invention makes it possible to meet these needs by presenting embolic microspheres comprising a hydrophilic cross-linked polymer matrix that is non-biodegradable, solid, calibrated, elastic, compressible, and has a controlled degree of swelling that is sufficient for persistent targeted embolic therapy.

[0026] The mechanical properties of the microspheres of the present invention (swellability, elasticity, solidity, resistance to compression) enable them to be suitable for injection and to provide a sufficient and durable level of embolic therapy when injected into the vasculature of a mammal, preferably a human.

[0027] The present invention is primarily a crosslinked polymer matrix comprising at least: a) N-vinylpyrrolidone, and a compound of formula (I): (CH2=CR1)-CO-D (I) (In the formula, D represents OZ or NH-Z, Z represents (C1-C6) alkyl, -(CR2R3) m -CH3, -(CH2-CH2-O) m -H, -(CH2-CH2-O) m -CH3, -C(R4OH) m or -(CH2) m-NR5R6, where m is an integer from 1 to 30; R1, R2, R3, R4, R5 and R6 each independently represent H or (C1-C6) alkyl. 20% to 95% of hydrophilic monomers selected from the monomers b) a compound of formula (IIa) or (IIb): (CH2=CR7)CO-NH-A-HN-OC(CR8=CH2) (IIa), or (CH2=CR7)CO-OAO-OC(CR8=CH2)(IIb) (Wherein, R7 and R8 each independently represent H or (C1-C6) alkyl; and A alone or together with at least one of the atoms to which it is attached represents (C1-C6) alkylene, polyethylene glycol (PEG), polysiloxane, poly(dimethylsiloxane) (PDMS), polyglycerol ester (PGE), or bisphenol A. 1% to 15% of a non-biodegradable linear or branched hydrophilic crosslinking monomer; and c) 1.5% to less than 6% of transfer agents selected from alkyl halides and cycloaliphatic or aliphatic thiols, in particular having from 2 to 24 carbon atoms and, optionally, further functional groups selected from amino, hydroxy and carboxy groups. For non-biodegradable embolic microspheres comprising a crosslinked matrix based on, the percentages of monomers a) and b) are given in moles relative to the total number of moles of monomer, and the percentage of compound c) is given in moles relative to the number of moles of hydrophilic monomer a).

[0028] In the context of the present invention, the addition of a transfer agent during the polymerization of the crosslinked matrix of the microspheres according to the invention makes it possible to increase the swelling degree of the microspheres. The increase in swelling degree leads to a decrease in the dry extract of the microspheres in a given volume and thus a higher proportion of water, making them easier to inject. Surprisingly, the presence of this transfer agent improves the elastic properties, as well as the properties of swelling and resistance to compression. The inventors have found that the addition of a transfer agent selected from those mentioned above, in a proportion of 1.5 mol% to less than 6 mol%, preferably 1.5% to 4.5%, preferably 3%, compared to the number of moles of hydrophilic monomer a), to the reaction mixture in the polymerization of a crosslinked matrix containing a hydrophilic polymer makes it possible to improve the mechanical properties of the non-biodegradable embolic microspheres, i.e. to enhance their swelling, their elasticity, their solidity and to improve their resistance to compression.

[0029] These characteristics allow the microspheres of the invention to be injected into an individual using a catheter or microcatheter and to produce a targeted embolism that is total and curative.

[0030] In particular, the inventors have discovered that the amount of transfer agent added to the reaction mixture must be closely controlled to meet the above requirements.

[0031] Thus, the swelling, elasticity and compressibility of the microspheres are optimal at 1.5% or more of the transport agent, on a molar basis, compared to the number of moles of hydrophilic monomer a) present in the reaction mixture. Microspheres obtained at levels below 1.5% are not sufficiently mobile to allow injection through a microcatheter.

[0032] When the transfer agent is present in the reaction mixture in an amount greater than 6%, the non-biodegradable embolic microspheres are too compressible, not solid enough, and break down.

[0033] Elasticity is also an important parameter: microspheres with low elasticity undergo less deformation due to the pressure of the vessel wall and remain localized in the proximal region of the vessel into which they are injected.

[0034] The present invention also relates to embolic microspheres loaded with active substances, which make it possible to combine vascular occlusion with the delivery of active substances.

[0035] The invention furthermore advantageously relates to a pharmaceutical composition comprising non-biodegradable embolic microspheres as defined above, together with a pharma- ceutically acceptable medium intended for administration by injection.

[0036] The present invention also relates to a kit comprising a pharmaceutical composition as defined above and at least one means of injection of said composition for parenteral administration of said composition.

[0037] The present invention also relates to a kit comprising, on the one hand, a pharmaceutical composition as defined above, and, on the other hand, a contrast agent for imaging by X-ray, magnetic resonance or ultrasound examination, and optionally at least one means of injection for parenteral administration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] The expression "matrix based on" naturally means a matrix that contains only mixtures and / or products of reactions between base components used in the heterogeneous polymerization of this matrix, preferably products of reactions between different base components used in this matrix, many of which are intended or likely to react, at least in part, with each other or with their close chemical environment during the different steps of the preparation method of the matrix, in particular during the polymerization step. The base components are therefore reactants that are intended to react with each other during the polymerization of the matrix. The base components are therefore added to a reaction mixture that optionally further comprises a solvent or a mixture of solvents and / or other additives, such as at least one salt and / or at least one polymerization initiator and / or at least one stabilizer, such as PVA. In the context of the present invention, the reaction mixture comprises at least the monomers a), b) and transfer agent c) as described in the present description as base components, and at least one solvent, preferably a mixture of solvents including aqueous and organic solvents, such as non-polar aprotic solvents, such as a water / toluene mixture. Optionally, the reaction mixture may contain a polymerization initiator, such as t-butyl peroxide, benzoyl peroxide, azobiscyanovaleric acid (also known as 4,4'-azobis(4-cyanopentanoic acid)), AIBN (azobisisobutyronitrile), 1,1'-azobis(cyclohexanecarbonitrile) or one or more thermal initiators, such as 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (106797-53-9); -hydroxy-2-methylpropiophenone (Darocur® 1173, 7473-98-5), 2,2-dimethoxy-2-phenylacetophenone (24650-42-8), 2,2-dimethoxy-2-phenylacetophenone (Irgacure®, 24650-42-8) or 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (Irgacure®, 71868-10-5).

[0039] Thus, according to the invention, the matrix is ​​based at least on the monomers a), b) and the transfer agent c) described in this description, these compounds therefore being the base components.

[0040] Thus, in the present description, expressions similar to "The "[base component X] is added to the reaction mixture in an amount of YY to YYY% in particular" and "The crosslinking matrix is ​​based on [base component X] in an amount of YY to YYY% in particular" are to be interpreted in a similar manner. Furthermore, expressions similar to "The reaction mixture comprises at least [base component X]" and "The crosslinking matrix is ​​based on at least [base component X]" are to be interpreted in a similar manner.

[0041] "Organic phase" of the reaction mixture means, within the meaning of the present invention, the phase which comprises the organic solvent and the compounds which are soluble in said organic solvent, in particular the monomers, the transfer agent and the polymerization initiator.

[0042] "(C X ~C Y By "alkyl group" in the sense of the present invention is meant a linear or branched saturated monovalent hydrocarbon-containing chain containing X to Y carbon atoms, X and Y being integers between 1 and 36, preferably between 1 and 18, in particular between 1 and 6. Mention may be made by way of example of the methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl or hexyl groups.

[0043] "(C X ~C Y By "aryl" in the sense of the present invention is meant an aromatic hydrocarbon-containing group, preferably containing X to Y carbon atoms, where X and Y are integers between 5 and 36, preferably 5 to 18, in particular 5 to 10, and containing a ring or several fused rings. By way of example, mention may be made of the phenyl or naphthyl group.

[0044] "(C X ~C Y) Heteroaryl" in the sense of the present invention means an aromatic group containing X to Y ring atoms, for example one or more, advantageously 1 to 4 and even more advantageously 1 or 2 heteroatoms such as sulfur, nitrogen or oxygen atoms, the other ring atoms being carbon atoms. X and Y are integers between 5 and 36, preferably 5 to 18, in particular 5 to 10. Examples of heteroaryl groups include furyl, thienyl, pyrrolyl, pyridinyl, pyrimidinyl, pyrazolyl, imidazolyl, triazolyl, tetrazolyl or indyl groups.

[0045] "(C X ~C Y By "alkylene group" in the sense of the present invention is meant a linear or branched divalent hydrocarbon-containing chain containing X to Y carbon atoms, X and Y being integers between 1 and 36, preferably between 1 and 18, in particular between 1 and 6. Mention may be made, by way of example, of the methylene, ethylene, propylene, butylene, pentylene or hexylene groups.

[0046] "(C X ~C Y A "cycloalkylene group" in the sense of the present invention means a saturated divalent cyclic hydrocarbon-containing group containing X to Y ring carbon atoms, where X and Y are integers between 3 and 36, preferably between 3 and 18, in particular between 3 and 6. Mention may be made, by way of example, of the cyclopropylene group, the cyclohexylene group or the cyclopentylene group.

[0047] "(C X ~C Y By "alkenylene group" in the sense of the present invention is meant a linear or branched divalent hydrocarbon-containing chain containing X to Y carbon atoms, X and Y being integers between 2 and 36, preferably between 2 and 18, in particular between 2 and 6, and at least one double bond. By way of example, mention may be made of the vinylene (ethenylene) or propenylene group.

[0048] "(C X ~C YA "cycloalkenylene group" in the sense of the present invention means a saturated divalent cyclic hydrocarbon-containing group containing X to Y ring carbon atoms, where X and Y are integers between 3 and 36, preferably 3 to 18, in particular 3 to 6, and at least one double bond.

[0049] "(C X ~C Y A ")alkynylene group" in the sense of the present invention means a linear or branched divalent hydrocarbon-containing chain containing X to Y carbon atoms, X and Y being integers between 2 and 36, preferably between 2 and 18, in particular between 2 and 6, and at least one triple bond.

[0050] "(C X ~C Y A "cycloalkynylene group" in the sense of the present invention means a saturated divalent cyclic hydrocarbon-containing group containing X to Y ring carbon atoms, where X and Y are integers between 3 and 36, preferably 3 to 18, in particular 3 to 6, and at least one triple bond.

[0051] "(C X ~C Y ")Arylene" means, within the meaning of the present invention, a divalent aromatic hydrocarbon-containing radical containing X to Y carbon atoms, where X and Y are integers between 5 and 36, preferably 5 to 18, in particular 5 to 10, and containing one or more fused rings. By way of example, there may be mentioned the phenylene radical.

[0052] "(C X ~C Y "Heteroarylene" means, in the sense of the present invention, a divalent aromatic radical containing X to Y ring atoms, for example one or more, advantageously 1 to 4 and even more advantageously 1 or 2 heteroatoms such as sulfur, nitrogen or oxygen atoms, and the other ring atoms being carbon atoms. X and Y are integers between 5 and 36, preferably 5 to 18, in particular 5 to 10.

[0053] By "divalent radical" is meant within the meaning of the present invention a radical having a valence of two, i.e. a radical having two covalent, polar covalent or ionic chemical bonds. Said radical may for example contain carbon and / or oxygen atoms.

[0054] "Dry extract" means within the meaning of the present invention the mass of dry microspheres contained in 1 ml of water-swellable microspheres.

[0055] In the context of the present invention, a "transfer agent" refers to a compound that has at least one weak chemical bond. This agent reacts with the radical sites of a growing polymer chain, terminating the chain growth. In the chain transfer process, the radical is temporarily transferred to the transfer agent, and growth is resumed by transferring the radical to another polymer or monomer.

[0056] Advantageously, said chain transfer agent is selected from the group consisting of mono- or polyfunctional thiols and alkyl halides.

[0057] Alkyl halides which may serve as transfer agents include, inter alia, bromotrichloromethane, tetrachloromethane, and tetrabromomethane.

[0058] Particularly advantageously, the chain transfer agent is an alicyclic or aliphatic thiol, typically having from 2 to about 24 carbon atoms, preferably from 2 to 12 carbon atoms, more preferably 6 carbon atoms, and optionally having further functional groups selected from amino groups, hydroxy groups and carboxy groups.

[0059] Particularly preferred examples of chain transfer agents are thioglycolic acid, 2-mercaptoethanol, dodecanethiol, hexanethiol, and mixtures thereof, preferably hexanethiol.

[0060] In the context of the present invention, the transfer agent is present in the reaction mixture in an amount of less than 1.5% to 6%, preferably 1.5% to 4.5% and in particular 3%, in molar terms, compared to the number of moles of hydrophilic monomer a).Thus, in the context of the present invention, the matrix is ​​based on the transfer agent in an amount of less than 1.5% to 6%, preferably 1.5% to 4.5% and in particular 3%, in molar terms, compared to the number of moles of hydrophilic monomer a).

[0061] In a preferred embodiment, the matrix of the non-biodegradable embolic microspheres according to the invention is based on the transfer agent in an amount of 1.5 to 4.5 mol % compared to the number of moles of hydrophilic monomer a).

[0062] Advantageously, the microspheres according to the invention contain between 1.5% and 3%, preferably 3%, of a crosslinked matrix based on a transfer agent.

[0063] The addition of the transfer agent to the reaction mixture in the above-mentioned amounts, in particular 1.5 to 3 mol %, compared to the number of moles of hydrophilic monomer a), makes it possible to avoid the presence of morphological defects on the microspheres of the invention, in particular after swelling and sterilization.

[0064] In the context of the present invention, the absence of morphological defects is defined as the absence of double or twin microspheres; the absence of microspheres themselves contained within other microspheres (i.e., bead-in-bead); the absence of fractured microspheres or remnants of fractured microspheres; the absence of stacks or clusters of microspheres; the absence of degraded microspheres; the absence of (non-spherical) deformed microspheres; the absence of microspheres with non-smooth surfaces or polymer debris under magnifications up to 100x; the absence of inclusion bodies in the microspheres; the absence of water droplets trapped in the microspheres.

[0065] The embolic microspheres of the present invention advantageously have Young's modulus values ​​typically between 3000 Pa and 30,000 Pa, preferably between 3000 Pa and 25,000 Pa, more preferably between 3000 Pa and 10,000 Pa, preferably between 5,000 Pa and 10,000 Pa, indicating high resistance of the microspheres to compression, which is related to the optimal swelling degree and elasticity of said microspheres.

[0066] Advantageously, in accordance with the present invention, the non-biodegradable embolic microspheres comprise a homogeneous cross-linked matrix.

[0067] "Homogeneous crosslinked matrix" means, within the context of the present invention, a matrix consisting of a three-dimensional polymer network in which the components are uniformly distributed. This limits the presence of structural defects and enhances the solidity of said network. In fact, typically, in the absence of a homogeneous crosslinked matrix, the polymer network will degrade at the level of its heterogeneous regions under the action of compressive forces.

[0068] In the context of the present invention, a sphere is defined as a surface where all points are equidistant from a point called the centre.

[0069] "Microspheres" in the sense of the present invention means spherical particles having a diameter after swelling of 20 to 1200 μm, for example 20 to 100 μm, 40 to 150 μm, 100 to 300 μm, 300 to 500 μm, 500 to 700 μm, 700 to 900 μm or 900 to 1200 μm, as measured by optical microscopy. Microspheres advantageously have a diameter small enough to be injected using a needle, catheter or microcatheter, with an internal diameter ranging from a few hundred μm to 2 mm or more.

[0070] The expression "post-swelling" means that the size of the microspheres is considered after the polymerization and sterilization steps involved in their preparation. The sterilization step comprises, for example, the passage of the microspheres after the polymerization step at high temperatures, typically above 100°C, preferably between 110°C and 150°C, preferably at 121°C, in an autoclave. During this sterilization step, the microspheres continue to swell. According to the invention, the overall swelling degree of the microspheres is controlled. The swelling degree can be determined by:

number

[0071] "Controlled degree of swelling" means in the sense of the present invention that the degree of swelling is reproducible as a function of batch, in particular that it differs from batch to batch by less than 15%.

[0072] "Sedimented microspheres" in the context of the present invention means microspheres that have been placed in a solution within a blood vessel and then left for a sufficiently long period of time without agitation so that they sink to the bottom of the vessel in which they are contained, thereby making it possible to remove the supernatant.

[0073] "Lyophilized microspheres" means, within the context of the present invention, microspheres that have been subjected to freezing followed by dehydration by sublimation.

[0074] "Hydrophilic monomer" means, within the meaning of the present invention, a monomer that has a strong affinity for water, i.e., that tends to dissolve in water, mix with water, become wet with water, or can swell with water after polymerization.

[0075] The hydrophilic monomer a) of the present invention is N-vinylpyrrolidone and a compound represented by the following formula (I): (CH2=CR1)-CO-D (I) (In the formula, D represents OZ or NH-Z, Z represents (C1-C6) alkyl, -(CR2R3) m -CH3, -(CH2-CH2-O) m -H, -(CH2-CH2-O) m -CH3, -C(R4OH) m or -(CH2) m -NR5R6, where m preferably represents an integer between 1 and 10, more preferably m is equal to 4 or 5. The monomer is selected from the group consisting of:

[0076] Advantageously, the hydrophilic monomer a) according to the invention is selected from the group consisting of N-vinylpyrrolidone, vinyl alcohol, 2-hydroxyethyl methacrylate, sec-butyl acrylate, n-butyl acrylate, t-butyl acrylate, t-butyl methacrylate, methyl methacrylate, N-dimethylaminoethyl (methyl)acrylate, N,N-dimethylaminopropyl (meth)acrylate, t-butylaminoethyl (methyl)acrylate, N,N-diethylaminoacrylate, poly(ethylene oxide) (meth)acrylate, methoxypoly(ethylene oxide) (meth)acrylate, butoxypoly(ethylene oxide) (meth)acrylate, poly(ethylene glycol) (meth)acrylate, methoxypoly(ethylene glycol) (meth)acrylate, butoxypoly(ethylene glycol) (meth)acrylate, poly(ethylene glycol) methyl ether methacrylate (m-PEGMA), and mixtures thereof.

[0077] More advantageously, the hydrophilic monomer a) is poly(ethylene glycol) methyl ether methacrylate (m-PEGMA).

[0078] In the context of the present invention, the hydrophilic monomer a) is in particular present in the reaction mixture in an amount, in molar terms, of 20% to 95%, preferably 30% to 95%, more preferably 45% to 95%, preferably 45% to 75%, in particular 45% to 70% and more particularly 45% to 65%, compared to the total number of moles of monomers.

[0079] "Cross-linking monomer" means, in the sense of the present invention, a monomer that is at least difunctional but also polyfunctional, having a double bond at each polymerizable end. The cross-linking monomer allows the formation of a cross-linked network in combination with other monomers in the mixture. The structure and amount of the cross-linking monomer in the mixture of monomers can be easily selected by the skilled artisan to provide the desired cross-linking density. The cross-linking agent is also advantageous for the stability of the microspheres. The cross-linking agent prevents the microspheres from being soluble in any solvent whatever. The cross-linking agent also makes it possible to improve the compressibility of the microspheres, which is favorable for embolotherapy.

[0080] "Non-biodegradable hydrophilic crosslinker" means, in the context of the present invention, a crosslinker as defined above that has a strong affinity for water and cannot be degraded under physiological conditions of the mammalian body, in particular the human body. In fact, biodegradation of a molecule is permitted when the latter has sufficient functional sites that are cleavable under physiological conditions and / or at physiological pH (generally around 7.4), in particular by endogenous enzymes of the mammalian body, in particular the human body. Functional sites that are cleavable under physiological conditions are in particular amide bonds, ester bonds and acetals. Therefore, molecules that contain an insufficient number of said functional sites will be considered non-biodegradable. In the context of the present invention, the crosslinking monomer has less than 20 functional sites that are cleavable under physiological conditions, preferably less than 15 such sites, more preferably less than 10 such sites, even more preferably less than 5 such sites.

[0081] The non-biodegradable linear or branched hydrophilic crosslinkers according to the invention are in particular non-biodegradable crosslinkers that are soluble in organic solvents and contain diacrylate, methacrylate, acrylamide and / or methacrylamide polymerizable groups.

[0082] Advantageously, the crosslinking agent has the following general formula (IIa) or (IIb): (CH2=CR7)CO-NH-A-HN-OC(CR8=CH2) (IIa), (CH2=CR7)CO-OAO-OC(CR8=CH2) (IIb) where R7 and R8, independently of each other, represent H or (C1-C6) alkyl, such as a methyl group, preferably R7 and R8 represent H; and A preferably represents, alone or in combination with at least one of the atoms to which it is attached, such as (C1-C6) alkylene, polyethylene glycol (PEG), polysiloxane, poly(dimethylsiloxane) (PDMS), polyglycerol ester (PGE) or bisphenol A.

[0083] Even more advantageously, A represents, alone or in combination with at least one of the atoms to which it is attached, such as (C1-C6)alkylene or polyethylene glycol (PEG), preferably polyethylene glycol (PEG).

[0084] In relation to the above definition of A, the polyethylene glycol has a length in the range of 200 to 10000 g / mol, preferably 200 to 2000 g / mol, more preferably 500 to 1000 g / mol.

[0085] Examples of cross-linking monomers that may be used in the context of the present invention may include, but are not limited to, 1,4-butanediol diacrylate, pentaerythritol tetraacrylate, methylene bisacrylamide, glycerol 1,3-diglycerolate diacrylate, and poly(ethylene glycol) dimethacrylate (PEGDMA).

[0086] Advantageously, the cross-linking monomer is poly(ethylene glycol) dimethacrylate (PEGDMA) with polyethylene glycol units having a length in the range of 200 to 10000 g / mol, preferably 200 to 2000 g / mol, more preferably 500 to 1000 g / mol.

[0087] In the context of the present invention, the crosslinking monomer is in particular present in the reaction mixture in an amount of 1% to 15%, preferably 2% to 10%, in particular 2% to 7%, more particularly 2% to 5%, in particular 5 mol %, compared to the total number of moles of monomers.

[0088] In a particular embodiment of the present invention, the crosslinked polymer matrix of the microspheres is based solely on the base components a), b) and c) as defined above in the above ratios, and no other base components are added to the reaction mixture. It is therefore clear that the sum of the above ratios of monomers a) and b) must be equal to 100%.

[0089] According to a particular embodiment of the invention, the crosslinked matrix of the microspheres according to the invention further comprises the following formula (III): (CH2=CR9)-ME (III) (In the formula, R9 represents H or (C1-C6) alkyl; M represents a single bond or a divalent radical having 1 to 20 carbon atoms, preferably a single bond; E represents an ionizable or ionizable group, E is preferably -COOH, -COO-, -SO3H, -SO3 - , -PO4H2, -PO4H - , -PO4 2- , -NR 10 R 11 , -NR 12 R 13 R 14 + is selected from the group consisting of ·R 10 , R 11 , R 12 , R 13 and R 14 each independently represents H or (C1-C6) alkyl. Based on at least one ionizable or ionizable monomer of

[0090] "Ionized or ionizable group" means, within the meaning of the present invention, a group that may be charged or in charged form (in the form of an ion), i.e., that has at least one positive or negative charge, depending on the pH of the medium. For example, a COOH group may be ionized in the form of COO-, an NH2 group may be ionized in the form of NH3 + It may be in the ionized form of

[0091] The introduction of ionized or ionizable monomers into the reaction mixture makes it possible to increase the hydrophilicity of the resulting microspheres and thus increase their swelling degree, making them easier to inject through catheters and microcatheters. The presence of ionized or ionizable monomers in particular facilitates the loading of active substances inside the microspheres.

[0092] Preferably, the ionizable or ionizable monomer is advantageously a cationic monomer selected from the group consisting of (methacryloyloxy)ethyl phosphorylcholine, 2-(dimethylamino)ethyl (meth)acrylate, 2-(diethylamino)ethyl) (meth)acrylate and 2-((meth)acryloyloxy)ethyl)trimethylammonium chloride; advantageously, the cationic monomer is (diethylamino)ethyl (meth)acrylate. Advantageously, the crosslinked matrix of the microspheres according to the invention may be obtained by adding to the reaction mixture between 1 and 40 mol% of said cationic monomer based on the total amount of monomers. Preferably, the crosslinked matrix according to the invention is obtained by adding to the reaction mixture, in molar units, between 5% and 15%, preferably 10%, of ionizable or ionizable monomer compared to the total number of moles of monomer when the microspheres obtained are not intended to be loaded with active substances. According to another embodiment, when the microspheres are intended to be loaded with active substances, the crosslinked matrix according to the invention is obtained by adding between 20% and 40% of ionizable or ionizable monomers to the reaction mixture, preferably between 20% and 30%, preferably 30 mol%, compared to the total number of moles of monomers.

[0093] In another advantageous embodiment, the ionized or ionizable monomer is advantageously an anionic monomer selected from the group consisting of acrylic acid, methacrylic acid, 2-carboxyethyl acrylate, 2-oligomers of carboxyethyl acrylate, 3-sulfopropyl (meth)acrylate, potassium salt of 2-((methacryloyloxy)ethyl)dimethyl-(3-sulfopropyl)ammonium and hydroxide. Advantageously, the crosslinked matrix of the non-biodegradable embolic microspheres according to the invention may be obtained by adding to the reaction mixture between 1 and 40 mol %, more advantageously between 10 and 30 mol %, of said anionic monomer based on the total amount of monomers.

[0094] Particularly advantageously, the ionizable or ionizable monomer is methacrylic acid. Advantageously, the crosslinked matrix according to the invention is based on methacrylic acid (MA) in an amount between 10 and 30 mol %, based on the total amount of monomers.

[0095] According to a preferred embodiment of the invention, the crosslinked matrix of the microspheres according to the invention is further based on at least one halogenated monomer, preferably an iodinated monomer.

[0096] The introduction of halogenated monomers, preferably iodized monomers, has the effect of increasing the density of the resulting microspheres. Surprisingly, the inventors have discovered that when halogenated monomers, typically iodized monomers, are advantageously used in amounts between 1 and 15 mol% compared to the total number of monomers in the reaction mixture for obtaining the crosslinked matrix of the invention, the resulting embolization microspheres form an optimally stable suspension in a mixture containing 50% normal saline and 50% contrast agent. In other words, the introduction of halogenated monomers, especially iodized monomers, in the above amounts makes it possible to prevent the microspheres from floating on the surface of said mixture.

[0097] In the context of the present invention, the halogenated monomer is in particular added to the reaction mixture in an amount, in moles, between 5% and 15%, preferably between 5% and 10% and more particularly between 5% and 7% compared to the total number of moles of monomer.

[0098] Furthermore, when less than 15% by mole of halogenated monomer is used compared to the total number of moles of monomer, the resulting microspheres are not radiopaque: the halogenated monomer is introduced in an amount insufficient to impart radiopacity to the microspheres.

[0099] Advantageously, the halogenated monomer has the following general formula (IV): (CH2=CR 15 )-CO-Y (IV) (In the formula, · Y is OW, (OR 16 ) p -W, (NH-R16 ) p -W or NH-W, W represents Ar, L-Ar, and p is an integer between 1 and 10, preferably between 1 and 4, where: Ar is (C5-C 36 ) aryl group or (C5-C 36 ) heteroaryl group, which is substituted with one, two or three atoms of iodine and / or bromine, and optionally represents a (C1-C 10 ) alkyl, -NR a R b , -NR c COR d , -COOR e , -OR f , -OCOR g , -CONR h R i , -OCONR j R k , -NR l COOR o , -N r CONR s R t , -OCOOR u , and -COR v is substituted with 1 to 4, preferably 2 or 3, groups selected from L is -(CH2) n -, -(HCCH) n -, -O-, -S-, -SO-, -SO2-, -OSO2 - , -NR 17 -, -CO-, -COO-, -OCO-, -OCOO-, -CONR 18 -, -NR 19 CO-, -OCONR 20 -, -NR 21 COO- or -NR 22 CONR 23 -, where n is an integer from 1 to 10; ·R 17 ~R 23 and R a ~R v are each independently a hydrogen atom, (C1-C 10 ) alkyl, and the (C1-C 10) Alkyl is optionally substituted with 1 to 10 OH groups or -(CH2-CH2-O) q substituted with -R' group, R' being a hydrogen atom or -(C1-C6)alkyl, and q being an integer between 1 and 10, preferably between 1 and 5; ·R 15 represents H or (C1-C6) alkyl; ·R 16 is (C1~C 36 ) alkylene, (C3-C 36 ) Cycloalkylene, (C2-C 36 ) Alkenylene, (C3-C 36 )Cycloalkenylene, (C2-C 36 ) Alkynylene, (C3-C 36 ) Cycloalkynylene, (C5-C 36 )Arylene and (C5-C 36 ) heteroarylene) It is.

[0100] In the context of the present invention, the halogenated monomer is more advantageously a monomer of general formula (IV) as defined above, where Y is NH-W, OW or (OR 16 ) p -W, advantageously NH-W or (OR 16 ) p -W, more advantageously (OR 16 ) p -W, W represents Ar or L-Ar, p, R 16 , L and Ar are as defined above. 16 is (C1~C 36 ) alkylene, especially (C1-C 18 ) alkylene, more particularly (C1-C6) alkylene; L represents -OCO-; and Ar represents one, two or three atoms of iodine and / or bromine, preferably iodine, and optionally -NR a R b , -NR c COR d , -COOR e , -OCOR g , -CONR hR i , -OCONR j R k , -NR l COOR o - and -N r CONR s R t , preferably -NR a R b , -NR c COR d (C5 to C 36 ) Aryl, especially (C5-C 10 ) aryl, more particularly phenyl.

[0101] Advantageously, the halogenated monomer is a monomer of general formula (IV) as defined above, where Y is NH-W or (OR 16 ) p -W, more advantageously (OR 16 ) p -W, W represents Ar or L-Ar, p, R 16 , L and Ar are as defined above. 16 is (C2~C 36 ) Alkylene, especially (C2-C 18 ) alkylene, more particularly (C2-C6) alkylene; L is -OCO-, -C(O)NR 17 - or -NR 18 C(O)-; and Ar represents one, two or three atoms of iodine and / or bromine, preferably iodine, and optionally -NR a R b , -NR c COR d , -COOR e , -OCOR g , -CONR h R i , -OCONR j R k , -NR l COOR o - and -N r CONR s R t , preferably -NR a R b , -NRc COR d and -C(O)NR h R i (C5 to C 36 ) Aryl, especially (C5-C 10 ) aryl, more particularly phenyl.

[0102] Advantageously, Ar is a fluorine atom, preferably 3 atoms of iodine and / or bromine, and optionally (C1-C 10 ) alkyl, -NR a R b , -NR c COR d , -COOR e , -OCOR g , -CONR h R i , -OCONR j R k , -NR l COOR o - and -N r CONR s R t (C5 to C 10 ) aryl, more particularly phenyl.

[0103] Advantageously, Ar is a fluorine atom, preferably 3 atoms of iodine and / or bromine, and optionally (C1-C 10 ) alkyl, -NR a R b , -NR c COR d , -COOR e , -OCOR g , -CONR h R i , -OCONR j R k , -NR l COOR o - and -N r CONR s R t From this, advantageously, (C1 to C 10 ) alkyl, -NR a R b , -NR cCOR d , -COOR e , -CONR h R i , -NR l COOR o - and -N r CONR s R t represents a phenyl substituted with two groups selected from:

[0104] Advantageously, the halogenated monomer is a monomer of general formula (IV) as defined above, where Y is O-C6H4I, O-C6H3I2, O-C6H2I3, NH-C6H4I, NH-C6H3I2, NH-C6H2I3, O-CH2-CH2-C(O)-C6H4I, O-CH2-CH2-OC(O)-C6H3I2, O-CH2-CH2-O It represents C(O)-C6H2I3, NH-CH2-CH2-C(O)-C6H4I, NH-CH2-CH2-OC(O)-C6H3I2 or NH-CH2-CH2-OC(O)-C6H2I3, in particular O-C6H2I3, NH-C6H2I3, O-CH2-CH2-OC(O)-C6H2I3 or NH-CH2-CH2-OC(O)-C6H2I3.

[0105] In another embodiment, the halogenated monomer has the following general formula (VI): (CH2=CR 29 )-CO-Y' (VI) (In the formula, ·R 29 represents H or (C1-C6) alkyl; · Y' is (OR 30 )t-W'-Ar', or NH-W'-Ar' (t is an integer between 1 and 10, preferably between 1 and 4); ·R 30 is (C2~C 36 ) alkylene; W' is a single bond, -CONR 31 - or -NR 32 CO- stands for; Ar' is (C5-C 36) aryl group, which is substituted with one, two or three atoms of iodine and / or bromine, and optionally represents a (C1-C 10 ) alkyl, -NR 33 R 34 , -NR 35 COR 36 , -COOR 37 , -OR 38 , -OCOR 39 , -CONR 40 R 41 , -OCONR 42 R 43 , -NR 44 COOR 45 , N.R. 46 CONR 47 R 48 , -OCOOR 49 , and -COR 50 is substituted with 1 to 4, preferably 2 or 3, groups selected from ·R 31 and R 32 each independently represents a hydrogen atom or a (C1-C6) alkyl; ·R 33 ~R 50 are each independently a hydrogen atom, (C1-C 10 ) alkyl, and the (C1-C 10 ) Alkyl is optionally substituted with 1 to 10 OH groups or -(CH2-CH2-O) t’ -R" group, where R" is a hydrogen atom or -(C1-C6)alkyl, and t' is an integer between 1 and 10, preferably between 1 and 5. It is.

[0106] Advantageously, R 29 represents (C1-C6) alkyl, more preferably (C1-C3) alkyl, and more preferably methyl.

[0107] Advantageously, R 30 is (C2~C 18 ) alkylene, more particularly (C2-C6) alkylene, and more preferably ethylene.

[0108] Advantageously, R 31and R 32 represent, independently of one another, a hydrogen atom. W' therefore advantageously represents a single bond, -C(O)NH- or -NHC(O)-.

[0109] Advantageously, Ar' is a substituted or unsubstituted aryl group consisting of 1, 2 or 3 atoms of iodine and / or bromine, preferably iodine, and optionally (C1-C 10 ) alkyl, -NR 33 R 34 , -NR 35 C(O)R 36 , -C(O)OR 37 , -OR 38 , -OC(O)R 39 , -C(O)NR 40 R 41 , -OC(O)NR 42 R 43 , -NR 44 C(O)OR 45 , -NR 46 C(O)NR 47 R 48 , -OC(O)OR 49 , and -C(O)R 50 (C5 to C 10 ) aryl, more particularly phenyl.

[0110] Advantageously, Ar' is a substituted or unsubstituted aryl group consisting of iodine and / or bromine, preferably 3 atoms of iodine and optionally (C1 to C 10 ) alkyl, -NR 33 R 34 , -NR 35 C(O)R 36 , -C(O)OR 37 , -OR 38 , -OC(O)R 39 , -C(O)NR 40 R 41 , -OC(O)NR 42 R 43 , -NR 44 C(O)OR 45 , -NR 46 C(O)NR 47 R 48 , -OC(O)OR 49 , and -C(O)R50 (C5 to C 10 ) aryl, more particularly phenyl.

[0111] Advantageously, Ar' is a substituted or unsubstituted aryl group consisting of iodine and / or bromine, preferably 3 atoms of iodine and optionally (C1 to C 10 ) alkyl, -NR 33 R 34 , -NR 35 C(O)R 36 , -C(O)OR 37 , -OR 38 , -OC(O)R 39 , -C(O)NR 40 R 41 , -OC(O)NR 42 R 43 , -NR 44 C(O)OR 45 , -NR 46 C(O)NR 47 R 48 , -OC(O)OR 49 , and -C(O)R 50 Therefore, advantageously (C1 to C 10 ) alkyl, -NR 33 R 34 , -NR 35 C(O)R 36 , -C(O)OR 37 , -OR 38 , -C(O)NR 40 R 41 , -NR 44 C(O)OR 45 , -NR 46 C(O)NR 47 R 48 , -OC(O)OR 49 , and -C(O)R 50 represents a phenyl substituted with two groups selected from:

[0112] Advantageously, the halogenated monomer is a compound of general formula (VI): [ka] is selected from.

[0113] Advantageously, the halogenated monomer is the following compound: [ka] is selected from.

[0114] More advantageously, the halogenated monomer has the following formula (IVa): [ka] (Triiodobenzoyl)oxoethyl methacrylate (MAOETIB) or the following formula: [ka] 2-(2-(2-(2,3,5-triiodobenzamido)ethoxy)ethyl methacrylate.

[0115] In the context of the present invention, the crosslinked matrix of the microspheres according to the invention is further based on at least one colored monomer for their visualization with the naked eye, which makes it possible in particular to verify before injection that the suspension of the microspheres is appropriately homogeneous in the syringe and to monitor the speed of the injection.

[0116] Thus, according to a particular embodiment, the crosslinked matrix of the microspheres according to the invention further comprises the following general formula (V): [ka] (In the formula, Z1 and Z2 are independently H or OR 26 R 26 represents H or (C1-C6)alkyl, advantageously Z1 and Z2 represent H; X represents a halogen, such as H or Cl, advantageously H; ·R 24 is a linear or branched, (C1-C6) alkylene, (C5-C 36 )Arylene, (C5~C 18 ) Arylene-OR27 , (C5~C 18 ) Heteroarylene and (C5-C 18 )Heteroarylene-OR 28 R represents a group selected from 27 and R 28 represents (C1-C6) alkyl or (C1-C6) alkylene, advantageously R 24 represents a -C6H4-O-(CH2)2- group or a -C(CH3)2-CH2- group, ·R 25 represents H or (C1-C6) alkyl, preferably (C1-C6) alkyl, in particular methyl. Based on at least one colored monomer of.

[0117] Advantageously, the colouring monomer has the following formula (Va) or (Vb): [ka] It is.

[0118] In the context of the present invention, the colouring monomer is in particular added to the reaction mixture in an amount, in molar terms, of 0% to 1%, preferably 0% to 0.5%, more particularly 0.01% to 0.2%, more preferably 0.02% to 0.2% and even more particularly 0.04% to 0.1%, compared to the total number of moles of monomer.

[0119] Magnetic resonance imaging (MRI) is used in medical practice to provide two-dimensional cross-sectional images of the internal structures of a patient's body without exposing them to harmful radiation. The cross-linked matrix of the embolic microspheres according to the present invention may further be based on particles for visualizing the microspheres upon scanning from magnetic resonance imaging.

[0120] Advantageously, therefore, the crosslinked matrix of the microspheres according to the invention is further based on an agent that is visible in magnetic resonance imaging (MRI), such as nanoparticles of iron oxide, gadolinium chelates or magnesium chelates, advantageously nanoparticles of iron oxide, such as USPIO (ultrasmall superparamagnetic iron oxide or ultrasmall paramagnetic iron oxide = magnetic particles based on iron compounds, exhibiting superparamagnetic properties that are visible in MRI).

[0121] In the context of the present invention, the MRI-visible particles are advantageously added to the reaction mixture in an amount between 0% and 10%, preferably between 0.1% and 10%, by volume of the organic phase.

[0122] In the context of the present invention, when the crosslinked matrix of the microspheres does not comprise an ionized or ionizable monomer as a base component, it is advantageously: - 94.5% to 98%, preferably 94.5% to 96%, preferably 94.96% of hydrophilic monomer a); - 2% to 5%, preferably 3% to 5%, preferably 5% of a non-biodegradable hydrophilic crosslinking monomer b); - 1% to 3%, preferably 3% of a transfer agent c); - 0% to 0.5%, preferably 0.02% to 0.1%, preferably 0.04%, of a coloring monomer; and - 0% to 10%, preferably 0% to 5%, preferably 1% MRI visible particles where the nature of each of said monomers and their associated percentages are as defined above in the description. It is clear that the sum of said percentages of the monomers must equal 100%.

[0123] According to another embodiment of the invention, the microspheres according to the invention not loaded with an active substance are advantageously - 79.5% to 93%, preferably 80% to 90%, preferably 84.96% of hydrophilic monomer a); - 2% to 5%, preferably 3% to 5%, preferably 5% of a non-biodegradable hydrophilic crosslinking monomer b); - 1% to 3%, preferably 3% of a transfer agent c); - 5% to 15%, preferably 8% to 12%, preferably 10% of ionizable or ionizable monomers; - 0% to 0.5%, preferably 0.02% to 0.1%, preferably 0.04%, of a coloring monomer; and - 0% to 10%, preferably 0% to 5%, preferably 1% MRI visible particles wherein the nature of each of said monomers and their associated percentages is as defined above in the present description. It is clear that the sum of said percentages of monomers must equal 100%.

[0124] According to a preferred embodiment of the invention, the microspheres according to the invention not loaded with an active substance are advantageously - 63% to 95%, preferably 70% to 90%, preferably 75% to 80%, preferably 79.96% of hydrophilic monomer a); - 2% to 5%, preferably 3% to 5%, preferably 5% of a non-biodegradable hydrophilic crosslinking monomer b); - 1% to 3%, preferably 3% of a transfer agent c); - 5% to 15%, preferably 8% to 12%, preferably 10% of ionizable or ionizable monomers; - 5% to 7%, preferably 5% to 6%, preferably 5% of halogenated monomers; - 0% to 0.5%, preferably 0.02% to 0.1%, preferably 0.04%, of a coloring monomer; and - 0% to 10%, preferably 0% to 5%, preferably 1% MRI visible particles wherein the nature of each of said monomers and their associated percentages are as defined above in the present description. It is clear that the sum of said percentages of monomers must equal 100%.

[0125] In the context of the present invention, the microspheres according to the invention loaded with an active substance are advantageously - 45% to 65%, preferably 50% to 65%, preferably 55% to 65%, preferably 64.96% of hydrophilic monomer a); - 2% to 5%, preferably 3% to 5%, preferably 5% of a non-biodegradable hydrophilic crosslinker b); - 1% to 3%, preferably 3% of a transfer agent c); - 20% to 40%, preferably 30% to 40%, preferably 30%, of ionizable or charged monomers; - 0% to 0.5%, preferably 0.02% to 0.1%, preferably 0.04%, of a coloring monomer; and - 0% to 10%, preferably 0% to 5%, preferably 1% MRI visible particles wherein the nature of each of said monomers and their associated percentages are as defined above in the present description. It is clear that the sum of said percentages of monomers must equal 100%.

[0126] Preferably, the microspheres according to the invention loaded with an active substance are advantageously - 47.5% to 73%, preferably 50% to 70%, preferably 59.96% of hydrophilic monomer a); - 2% to 5%, preferably 3% to 5%, preferably 5% of a non-biodegradable hydrophilic crosslinker b); - 1% to 3%, preferably 3% of a transfer agent c); - 20% to 40%, preferably 30% to 40%, preferably 30%, of ionizable or charged monomers; - 5% to 7%, preferably 5% to 6%, preferably 5% of halogenated monomers; - 0% to 0.5%, preferably 0.02% to 0.1%, preferably 0.04%, of a coloring monomer; and - 0% to 10%, preferably 0% to 5%, preferably 1% MRI visible particles wherein the nature of each of said monomers and their associated percentages are as defined above in this description.

[0127] The crosslinked matrix of the microspheres according to the invention can be easily synthesized by many methods familiar to those skilled in the art. By way of example, the crosslinked matrix according to the invention may typically be obtained by direct or inverse suspension polymerization, as described below and in the examples.

[0128] Direct suspension may be carried out as follows. (a)(i) at least one hydrophilic monomer a) as defined above, at least one non-biodegradable hydrophilic crosslinker b) as defined above, and at least one transfer agent c) as defined above; (ii) a polymerization initiator present in an amount ranging from 0.1 to about 2 parts by weight per 100 parts by weight of monomer; (iii) a surfactant in an amount of about 5 parts by weight or less per 100 parts by weight of the aqueous phase, preferably about 3 parts by weight or less, and most preferably in the range of 0.2 to 1.5 parts by weight of the aqueous phase; and (iv) water to form an oil-in-water suspension; mixing or stirring a reaction mixture comprising (b) Polymerizing the base component

[0129] In this direct suspension process, the surfactant may be selected from the group consisting of hydroxyethylcellulose, polyvinyl alcohol (PVA), polyvinylpyrrolidone, polyethylene oxide, polyethylene glycol and polysorbate 20 (Tween® 20); preferably PVA.

[0130] The microspheres thus obtained are then washed and calibrated by techniques familiar to those skilled in the art.

[0131] The backsuspension may be carried out as follows. (a)(i) at least one hydrophilic monomer a) as defined above, at least one non-biodegradable hydrophilic crosslinker b) as defined above, and at least one transfer agent c) as defined above; (ii) a polymerization initiator present in an amount ranging from 0.1 to about 2 parts by weight per 100 parts by weight of monomer; (iii) a surfactant in an amount of about 10 parts by weight or less, preferably about 8 parts by weight or less, and most preferably in the range of 3 to 7 parts by weight per 100 parts by weight of the oil phase; and (iv) oil to form a water-in-oil suspension; mixing or stirring a reaction mixture comprising (b) Polymerizing the base component

[0132] In the above process, the polymerization initiator may be, in particular, t-butyl peroxide, benzoyl peroxide, azobiscyanovaleric acid (4,4'-azobis(4-cyanopentanoic) acid, 1,1'-azobis(also called cyclohexanecarbonitrile) or AIBN (azobisisobutyronitrile) or one or more thermal initiators, such as, for example, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (106797-53-9); 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (106797-53-9); It may be 2-methylpropiophenone (Darocur® 1173, 7473-98-5), 2,2-dimethoxy-2-phenylacetophenone (24650-42-8), 2,2-dimethoxy-2-phenylacetophenone (Irgacure®, 24650-42-8) or 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (Irgacure®, 71868-10-5).

[0133] In this inverse suspension process, the surfactant may be selected from the group consisting of sorbitan esters such as sorbitan monolaurate (Span® 20), sorbitan monopalmitate (Span® 40), sorbitan monooleate (Span® 80) and sorbitan trioleate (Span® 85), hydroxyethylcellulose, a mixture of glyceryl stearate and PEG stearate (Arlacel®), and cellulose acetate.

[0134] The oil used in the above process may be selected from paraffin oil, silicone oil, and organic solvents such as hexane, cyclohexane, ethyl acetate or butyl acetate.

[0135] When the crosslinked matrix according to the present invention is obtained by polymerization of at least one ionized or ionizable monomer, further drugs, active substances, diagnostic agents or macromolecules can be loaded onto the microspheres, i.e. adsorbed onto the crosslinked matrix, by non-covalent interactions, optionally in the presence of pharma- ceutically acceptable excipients familiar to those skilled in the art. This particular method of capturing drugs or active substances is called physical encapsulation. No particular requirements are imposed on the drugs or active substances to be loaded.

[0136] Loading may be achieved by many methods familiar to those skilled in the art, such as passive adsorption (swelling of the crosslinked matrix in the drug solution) or ionic interactions. These methods are described, for example, in the international application WO 2012 / 120138, in particular on page 22, line 20 to page 26, line 7. The efficiency of encapsulation depends mainly on the compatibility and / or favorable interactions between the two structures.

[0137] In the context of the present invention, the microspheres may be loaded with drugs, active substances or diagnostic agents, thus allowing their release at target sites present inside the mammalian body, in particular inside the human body. Thus, the crosslinked matrix of the microspheres according to the present invention may be loaded with drugs or active substances or diagnostic agents, advantageously having a molecular weight of less than 5000 Da, typically less than 1000 Da, the drugs or active substances being advantageously selected from the group consisting of anti-inflammatory agents, local anesthetics, analgesics, antibiotics, anticancer agents, steroids, antiseptics and mixtures thereof.

[0138] Preferably, the polymers according to the present invention may be loaded with anti-cancer drugs.

[0139] Anticancer drugs are preferably anthracyclines, such as doxorubicin, epirubicin or idarubicin, platinum complexes, compounds related to anthracyclines, such as mitoxantrone and nemorubicin, antibiotics, such as mitomycin C (Ametycine®), bleomycin and actinomycin D, other antineoplastic compounds, such as irinotecan, 5-fluoro-uracil (Adrucil®). , sorafenib (Nevaxar®), sunitinib (Sutent®), regorafenib, brivanib, orantinib, linsitinib, erlotinib, cabozantinib, foretinib, tivantinib, fotemustine, tauromustine (TCNU), carmustine, cytosine C, cyclophosphonamide, cytosine arabinoside (or cytarabine), paclitaxel, docetaxel, Taxel, methotrexate, everolimus (Afinitor®), PEG-arginine deiminase, tegafur / gimeracil / oteracil combination (Teysuno®), muparfostat, peretinoin, gemcitabine, bevacizumab (Avastin®), ramucirumab, floxuridine, immunostimulants such as GM-CSF (granulocyte-macrophage colony-stimulating factor) and its recombinant forms: molgramostim or sargramostim (Leukin®), OK-432 (Picibanil®), interleukin 2, interleukin 4 and tumor necrosis factor alpha (TNFα), antibodies, radioactive elements, complexes of these radioactive elements with chelates, nucleic acid sequences, and mixtures of one or more of these compounds, preferably mixtures of one or more anthracyclines.

[0140] Preferably, the anti-cancer agent is selected from anthracyclines, immunostimulants, platinum complexes, antineoplastic agents and mixtures thereof.

[0141] Even more preferably, the anti-cancer agent is selected from anthracyclines, antibodies, anti-neoplastic agents and mixtures thereof.

[0142] The antibody is, for example, selected from anti-PD-1, anti-PD-L1, anti-CTLA-4, anti-CEA (carcinoembryonic antigen), or a mixture thereof.

[0143] Anti-PD-1 is, for example, nivolumab or pembrolizumab.

[0144] Anti-PD-L1 is, for example, avelumab, durvalumab or atezolizumab.

[0145] The anti-CTLA-4 is, for example, ipilimumab or tremelimumab.

[0146] Even more preferably, the anticancer drug is selected from the group consisting of paclitaxel, doxorubicin, epirubicin, idarubicin, irinotecan, GM-CSF (granulocyte-macrophage colony-stimulating factor), tumor necrosis factor alpha (TNFα), antibodies, and mixtures thereof.

[0147] Preferably, the local anesthetic is selected from lidocaine, bupivacaine, and mixtures thereof.

[0148] The anti-inflammatory agent may be selected from ibuprofen, niflumic acid, dexamethasone, naproxen, and mixtures thereof.

[0149] In the context of the present invention, the polymer may be loaded, in particular by immediate adsorption, with macromolecules selected from the group consisting of enzymes, antibodies, cytokines, growth factors, clotting factors, hormones, plasmids, antisense oligonucleotides, siRNAs, ribozymes, DNA enzymes (also called DNAzymes), aptamers, anti-inflammatory proteins, bone morphogenetic proteins (BMPs), pro-angiogenic factors, vascular endothelial growth factors (VEGF) and TGFβ, and angiogenesis inhibitors or anti-tyrosine kinases, and mixtures thereof.

[0150] Anti-inflammatory proteins are for example infliximab or rilonacept and mixtures thereof.

[0151] Angiogenic factors are, for example, fibroblast growth factors (FGFs) and mixtures thereof.

[0152] Angiogenesis inhibitors are, for example, bevacizumab, ramucirumab, nesvacumab, olaratumab, vanucizumab, rilotumumab, emibetuzumab, aflibercept, ficlatuzumab, pegaptanib, and mixtures thereof.

[0153] Anti-tyrosine kinase agents include, for example, lenvatinib, sorafenib, sunitinib, pazopanib, vandetanib, axitinib, regorafenib, cabozantinib, fruquintinib, nintedanib, anlotinib, motesanib, cediranib, surufatinib, and doxorubicin. B Tinib (dov i tinib), linifanib, and a mixture of these.

[0154] Advantageously, the polymer may be loaded with a macromolecule selected from anti-tyrosine kinases, TGFβ, angiogenesis inhibitors, and mixtures thereof.

[0155] In a second aspect, the present invention relates to a pharmaceutical composition comprising a non-biodegradable embolic microsphere according to the invention, advantageously associated with a pharma- ceutical acceptable medium intended for administration by injection.

[0156] Examples of pharma- ceutically acceptable media include, but are not limited to, water for injection, saline also referred to as normal saline, starch, hydrogel, polyvinylpyrrolidone, polysaccharides, esters of hyaluronic acid, blood plasma, contrast agents for X-ray, magnetic resonance or ultrasound imaging, buffers, preservatives, gelling agents and / or surfactants. Advantageously, the pharma-ceutically acceptable media is normal saline, water for injection, contrast agents for X-ray, magnetic resonance or ultrasound imaging, or a mixture thereof. More advantageously, the pharma-ceutically acceptable media is normal saline, contrast agents for X-ray, magnetic resonance or ultrasound imaging, or a mixture of normal saline and contrast agents for X-ray, magnetic resonance or ultrasound imaging.

[0157] According to the invention, the contrast agent is preferably a contrast agent for imaging with X-rays. Advantageously, it is a non-ionic iodinated water-soluble contrast agent, such as iobitridol (Xenetix®), iopamidol (Iopamiron®, Isovue®), iomeprol (Iomeron®), ioversol (Optiray®, Optiject®), iohexol (Omnipaque®), iopentol (Imagopaque®), ioxytol (Oxilan®), iopromide (Ultravist®), metrizamide (Amipaque®), iosarchol (Melitrast®), iotrolan (Isovist®), iodixanol (Visipaque®), iosimenol and iosimide (Univist®), and mixtures thereof.

[0158] According to another embodiment, the contrast agent is a contrast agent for magnetic resonance imaging (MRI). Advantageously, it is a gadolinium chelate (Dotarem®).

[0159] According to another embodiment, the contrast agent is a contrast agent for ultrasound imaging. Advantageously, it is sulphur hexafluoride (Sonovue®).

[0160] In a particular embodiment of the invention, a pharmaceutical composition comprises non-biodegradable embolic microspheres according to the invention together with normal saline, said composition being intended to be mixed, prior to administration by injection, with at least one contrast agent for imaging by X-ray, magnetic resonance or ultrasound, in particular for imaging by X-ray, as defined above, said mixing comprising the preparation of a suspension of microspheres according to the invention.

[0161] The pharmaceutical composition advantageously has an acceptable injection viscosity.

[0162] In a particular embodiment according to the invention, the pharmaceutical composition according to the invention comprises non-biodegradable embolic microspheres according to the invention together with a mixture of normal saline and a contrast agent as defined above, the normal saline and the contrast agent being present in a ratio of 70 / 30 to 20 / 80, advantageously 50 / 50 to 20 / 80, preferably 50 / 50.

[0163] Advantageously, when the pharmaceutical composition according to the invention comprises microspheres obtained by polymerization of a reaction mixture comprising 5% to 10%, more preferably 5% to 7%, of halogenated monomer as described herein, said pharmaceutical composition comprises said microspheres together with a mixture of normal saline and a contrast agent in a ratio of between 80 / 20 and 0 / 100, preferably between 70 / 30 and 40 / 60, in particular 50 / 50. Preferably, said microspheres have a size of 500 to 700 μm, 700 to 900 μm or 900 to 1200 μm. In this way, the suspension of microspheres in solution is homogeneous and stable over the time required for injection.

[0164] In another embodiment according to the invention, when the pharmaceutical composition according to the invention comprises microspheres obtained by polymerization of a reaction mixture not containing halogenated monomers as described herein, said pharmaceutical composition comprises said microspheres together with a mixture of normal saline and a contrast agent in a ratio between 80 / 20 and 0 / 100.

[0165] The application fields of the non-biodegradable embolic microspheres according to the invention include vascular embolic therapy, especially in the case of uterine fibroids and chemoembolization, for example in the case of liver cancer, also called hepatocellular carcinoma (HCC) or primary liver cancer, which consists in eliminating the tumor by combining vascular occlusion with the delivery of one or more active substances or macromolecules loaded with the embolic microspheres. This technique makes it possible to concentrate the loaded drug at the level of the tumor, thus reducing the systemic concentration as well as any undesirable effects.

[0166] The non-biodegradable embolic microspheres according to the invention may be used for various biomedical purposes, as mentioned above, which means that they must be compatible with the human or mammalian body. More particularly, suitable biomedical materials do not have hemolytic properties.

[0167] The invention further relates to the specific use of a transfer agent in the polymerization of the crosslinked matrix contained in non-biodegradable embolic microspheres, in order to allow the injection of said microspheres, in particular in catheters or microcatheters with an internal diameter ranging from a few hundred μm to 2 mm or more. The invention also relates to the specific use of a transfer agent in the polymerization of the crosslinked matrix, in order to improve the mechanical properties (swellability, elasticity, solidity, resistance to compression). The transfer agent is in particular chosen from cycloaliphatic or aliphatic thiols, in particular having 2 to 24 carbon atoms, optionally bearing further functional groups chosen from amino, hydroxy and carboxy groups.

[0168] The present invention also relates to a kit comprising a pharmaceutical composition as defined above and at least one injection means for said composition intended for parenteral administration of said composition. According to the present invention, "injection means" means any means allowing parenteral administration. Advantageously, said injection means are one or more syringes and / or one or more syringes, which may be prefilled, and / or one or more catheters or microcatheters for administering said composition by injection.

[0169] Advantageously, the pharmaceutical composition present in said kit comprises microspheres according to the invention together with normal saline, a contrast agent or a mixture thereof.More advantageously, said pharmaceutical composition comprises microspheres according to the invention together with a mixture of normal saline and a contrast agent in a ratio of between 80 / 20 and 0 / 100, advantageously between 70 / 30 and 40 / 60, preferably 50 / 50.

[0170] Advantageously, when the microspheres according to the invention are obtained by polymerization of a reaction mixture containing between 5% and 10%, more preferably between 5% and 7%, of halogenated monomers, as described herein, said pharmaceutical composition comprises said microspheres together with a mixture of normal saline and a contrast agent, in a ratio between 60 / 40 and 0 / 100, advantageously 50 / 50.

[0171] According to another embodiment of the invention, when the microspheres according to the invention are obtained by polymerization of a reaction mixture free of halogenated monomers, as described herein, the pharmaceutical composition comprises said microspheres together with a mixture of normal saline and a contrast agent in a ratio between 80 / 20 and 0 / 100.

[0172] Advantageously, the injection means present in the kit according to the invention are suitable for parenteral administration of the pharmaceutical composition according to the invention. The size of the syringe or (micro)catheter will therefore be adapted as a function of the size of the microspheres according to the invention and the volume to be injected into the embolus. The skilled person will be able to select the suitable injection means.

[0173] The present invention also relates to a kit comprising, on the one hand, a pharmaceutical composition as defined above, and, on the other hand, at least one contrast agent for imaging by X-ray, magnetic resonance or ultrasound, and optionally at least one injection means intended for parenteral administration, the injection means being as defined above.

[0174] In the kit, the pharmaceutical composition and the imaging agent are packaged separately and are intended to be mixed immediately prior to administration by injection.

[0175] In said kit, the at least one imaging agent is as defined hereinabove. In particular, the at least one imaging agent is an imaging agent for X-ray imaging, as defined hereinabove.

[0176] In said kit, the pharmaceutical composition advantageously comprises the microspheres according to the invention together with a pharma- ceutically acceptable medium intended for administration by injection, which may be, for example but not limited to, water for injection, normal saline, starch, hydrogel, polyvinylpyrrolidone, polysaccharides, esters of hyaluronic acid and / or plasma. Preferably, in said kit, the pharmaceutical composition advantageously comprises the microspheres according to the invention together with normal saline or water for injection.

[0177] In said kit, the pharmaceutical composition is advantageously packaged directly in an injection means, in particular a syringe, suitable for injection of the embolization microspheres by the parenteral route.

[0178] In said kit, the contrast agent is advantageously packaged in a vial or directly in an injection means, in particular a syringe, suitable for injection of the embolization microspheres, in particular by the parenteral route.

[0179] In said kit, the ratio of pharma- ceutically acceptable medium to contrast agent is between 80 / 20 and 0 / 100, advantageously between 70 / 30 and 40 / 60, preferably between 50 / 50. Advantageously, when the microspheres according to the invention are obtained by polymerization of a reaction mixture comprising 5% to 10%, preferably between 5% and 7%, of halogenated monomers, as described herein, the ratio of pharma- ceutically acceptable medium to contrast agent is between 70 / 30 and 0 / 100, advantageously between 60 / 40 and 20 / 80, preferably between 50 / 50. According to another embodiment of the invention, when the microspheres according to the invention are obtained by polymerization of a reaction mixture comprising no halogenated monomers, as described herein, the ratio of pharma- ceutically acceptable medium to contrast agent is between 80 / 20 and 0 / 100. [Brief description of the drawings]

[0180] [Figure 1] Mean diameter of microspheres (MS) after sterilization as a function of the concentration of the transfer agent. [Diagram 2]Percentage of defect-free microspheres as a function of the concentration of the transfer agent. [Diagram 3] Examples of microspheres: A: 0% hexanethiol, no defects; B: 0% hexanethiol, crushed; C: 0% hexanethiol, deformed; D: 6% hexanethiol, no defects; E: 6% hexanethiol, crushed. [Figure 4] Dry extract as a function of the concentration of the transfer agent. [Diagram 5] Swelling degree as a function of the concentration of the transfer agent. [Figure 6] Young's modulus as a function of the concentration of the transport agent.

[0181] The examples presented below are intended to illustrate the present invention. Hereinafter, the term "microspheres", whether in the singular or plural form, will generally be abbreviated as MS. EXAMPLES

[0182] Materials and Methods ·material 2,2'-azobis(2-methylpropionitrile) (AIBN), poly(ethylene glycol) methacrylate (M n = 300 g.mol -1 ) (PEG), 1-hexanethiol (95%), methacrylic acid (99%), polyvinyl alcohol (M n =30000~70000g.mol -1 ) (PVA), thioglycolic acid (99%), 1-dodecanethiol (98%) were purchased from Sigma-Aldrich. Toluene and acetone were purchased from VWR. NaCl was purchased from Merck. Polyethylene glycol dimethacrylate (M n =1000g.mol -1 ) (PEGDMA-1000) was purchased from Polysciences Inc. The violet dye and iodinated monomer were synthesized in the Guerbet R&D center. All materials were used as received without any additional purification. ·method

[0183] morphology The morphological properties of the obtained MS were characterized by a Morphologi 4 instrument (Malvern Instruments, United Kingdom). The Morphologi 4 instrument can be used to create a database of MS images. It can show the size distribution of the measured MS. 26 different morphological parameters could be determined by the Morphologi 4 instrument. The diameter (μm) was the main parameter studied.

[0184] The MS were deposited on the sample holder of the Morphologi 4 instrument. 500 MS were imaged and stored in the software's database for more thorough analysis. Standard operating procedures (SOPs) were used in the imaging process to ensure uniformity of the measurements.

[0185] After each measurement, defective MSs were excluded from the totality of MSs (500 MSs). The most reliable method consisted of visually inspecting each MS and either removing them or storing them in an image database as a function of their defects and their completeness. Furthermore, histograms, mean diameters and standard deviations were obtained for defect-free MSs.

[0186] Analysis of the defect: There are various classes of microsphere (MS) defects, which are enumerated here. - Class 1: MS without defects -Class 2: Siamese twin MS -Class 3: Dual-core MS - Class 4: isolated, crushed MS - Class 5: Residues or residues of crushed MS -Class 6: MS piles after sterilization - Class 7: MS core without USPIO - Class 8: Very transparent MS (phantom MS) - Class 9: Stacks of MS in polymer fragments -Class 10: Cracked MS - Class 11: Oval objects containing several small MS - Class 12: Transformed MS

[0187] In the defect study based on 500 MSs tested, defective MSs were excluded. Thus, the percentage of defect-free MSs was calculated:

number

[0188] Dry extract, swelling by weight The dry extract is measured as follows: 1 ml of the piled MS is placed in a 5 ml Eppendorf vial, frozen at -80°C, and lyophilized overnight in a freeze dryer (Heto PowerDry LL1500, Thermo Scientific). The weight of the MS after lyophilization is then measured.

[0189] Measurements were performed on triplicate samples and the average value was taken as the final value of the dry weight of MS.

[0190] Swelling: To calculate the gravimetric swelling of MS, the same sample preparation as above was used.

number

[0191] Rheology and Compressibility The rheological properties of MS were measured with a HR2 Discovery rheometer (TA Instruments, USA). Young's modulus is measured using the uniaxial compression mode.

[0192] A plane-plane type geometry was used, with plates having a diameter of 50 mm and an initial spacing of 1600 μm. The temperature of the sample is maintained at 25° C. by the Peltier effect. Before the measurement, the normal force is set to 0 by the software. Then, a uniform bed with a monolayer of microspheres is deposited on the plate.

[0193] A first measurement is performed to measure the contact point with the MS and the linear deformation conditions.

[0194] For this, the gap between the plates is reduced from 1600 μm to 700 μm at a rate of 16.7 μm / s (1 mm / min) and the normal force is measured. The contact point corresponds to the gap between the plates where the normal force starts to be exerted. When continuing to reduce this gap between the plates, the normal force follows a linear state as a function of the applied deformation up to a certain point. The gap between the plates during this divergence corresponds to the exit from the linear state.

[0195] A second measurement is then performed three times in succession to determine the average value and the measurement error of Young's modulus. This second measurement consists of placing the top plate directly on the contact point and applying an axial strain up to a maximum value of exit from the linear state. The measured normal force then varies linearly as a function of the applied strain. The slope of this curve corresponds to Young's modulus.

[0196] Other methods used to measure Young's modulus (Method No. 2) Compression tests are performed on single microspheres with a compressor (Synergy 800, MTS, France) using a 3D printed piston with a diameter of 15.3 mm. The exerted force is measured with a force sensor of 2 N, providing accurate and reproducible measurements starting from 1 mN. The software TestWorks4 is the interface to control the piston and to record the data measured by the sensor. It is necessary to use a lamp (100 W bulb) to illuminate the cell containing the microsphere to be analyzed and to allow the camera to clearly see the microsphere and the piston. The image processing software ImageJ is used to measure the exact size of the microsphere by measuring the number of pixels in the image. The speed of the piston is fixed at 1 mm / min and the test starts with the piston positioned approximately 100 μm above the microsphere.

[0197] Together with the collected data (force, time and displacement measurements), Young's modulus is calculated using the Hertz model applicable to the compression of a sphere between two flat plates.

[0198] MS Injections MS was injected through a microcatheter to test its mechanical properties during injection. A solution consisting of 350 mg iodine / ml in 30 vol% contrast agent Xenetix® and 70 vol% normal saline was prepared. 20 mL of this solution was obtained using a 20 mL syringe and in parallel 2 mL of deposited MS was obtained using a 3 mL syringe from the bottle sterilized as above.

[0199] Two syringes (3 mL and 20 mL) are connected to a three-way stopcock. The MS is suspended in the above mixture by performing approximately 15 alternating transfers between the two syringes.

[0200] A 3 ml syringe is used to inject the solution of MS in suspension into a microcatheter of type Progreat® 2.8F (Terumo) or GlideCath® 4F or 5F (Terumo).

[0201] Example 1: Synthesis of microspheres (MS) (900-1200 μm) according to the present invention by direct suspension polymerization The aqueous solution of hydrolyzed polyvinyl alcohol and sodium chloride is poured into a reactor and heated to 50°C. An organic phase containing poly(ethylene glycol) methyl ether methacrylate (m-PEGMA) (hydrophilic monomer), poly(ethylene glycol) dimethacrylate (PEGDMA) (crosslinker), coloring monomer, methacrylic acid (ionized or ionizable monomer), transfer agent, and AIBN (initiator) dissolved in toluene is then fed to the reactor. Agitation is applied using a propeller-type stirrer at a suitable speed to obtain droplets of the desired diameter. The temperature is then increased to 80°C and agitation is continued for 12 hours. The mixture is then filtered through a 40 μm sieve and the MS is collected. The MS retained by the sieve is then washed three times with acetone and then three times with water. These washed MS are then sieved between a 900 μm sieve and a 710 μm sieve. The MS collected between these two sieves is then sterilized in an autoclave at 121°C for 20 minutes, which has the effect of swelling the MS and obtaining MS of the desired size, i.e. in this case 900-1200 µm.

[0202] The microspheres synthesized by the above method then have the following composition (Tables 1 and 1-2):

[0203] [Table 1]

[0204] [Table 1-2]

[0205] Example 2: Size of microspheres from Example 1 For each of batches 1 to 9 and L9, the average diameter of the microspheres is measured after sterilization to evaluate the effect of the concentration of the transfer agent on the size of the MS.

[0206] The MS was sterilized according to the procedure described above.

[0207] The average post-sterilization diameter (900-1200) of the calibrated MS for each of the batches is shown in Figure 1.

[0208] The diameter of the MS after sterilization increases from 923 to 1259 μm with increasing concentration of HT (batches 1, 2, 3, 4, 5, 6 and 7). The more transport agent the microspheres contain, the larger their size becomes.

[0209] Example 3: Percentage of defect-free microspheres from Example 1 The percentage of defective MS was calculated by the above method for samples of MS with sizes from 900 to 1200 μm (batches 1 to 9 and L9) containing different concentrations of HT as one or more different types of transfer agents. The results are shown in Figure 2.

[0210] From 0% to 1.5% HT (batches 1 to 4), the percentage of defect-free MS varies from 89% to 91%. This percentage increases from 1.5% transfer agent and reaches a maximum (>95%) at 3% transfer agent (batches 5, 8, 9 and L9).

[0211] The type of defect varies depending on the concentration of the transfer agent in the microspheres. Figure 3 shows two examples of the most commonly observed morphological defects. At concentrations between 0% and 1.5% of HT, MS are either mostly degraded (B) or deformed (C).

[0212] At concentrations of 6% or more of HT in MS, there are a very large number of bursting MS (see Figure 3).

[0213] Example 4: Dried extract of microspheres from Example 1 Figure 4 shows the dry extract (mg / ml) of MS calculated by the above method as a function of the concentration or nature of the transfer agent. The dry extract (mg) for a given volume of MS decreases linearly as the concentration of HT increases (batches 1, 2, 3, 4, 5, 6 and 7). The dry extract of MS for batch L9 is about 101 mg / mL. Without transfer agent, the dry mass of 1 mL of deposited MS is about 159 mg. At 6% HT, this dry extract is only about 52 mg.

[0214] Example 5: Swelling degree of microspheres from Example 1 The swelling degree of the microspheres was determined by the method described above for batches 1-9 and L9 to evaluate the effect of the concentration and nature of the transfer agent. The results are shown in Figure 5. It can be seen that with increasing concentration of HT, the resulting swelling degree increases.

[0215] For HT concentrations between 0% and 6%, the swelling by weight increases from 7 g / g to 26 g / g, which is about 8.88% for MS of batch L9.

[0216] Thus, MS without the transfer agent is not significantly swollen and has a very high dry weight. These data show that the various transfer agents tested impart a suitable degree of swelling.

[0217] Example 6: Rheology and compressibility of microspheres from Example 1 The compressibility of the microspheres can be characterized by measuring the Young's modulus by the method described above. The Young's modulus of batches 1 to 9 is shown in Figure 6. The results obtained with method No. 2 for the measurement of Young's modulus gave quite similar results.

[0218] It can be seen that as the concentration of HT increases from 0% to 3%, the Young's modulus decreases from about 13 kPa to about 6 kPa, and then reaches a plateau at about 6 kPa for the higher concentrations (4.5% and 6%).

[0219] MS containing between 0% and 0.5% HT (batches 1-4) are more solid and hard and not suitable for injection. The Young's modulus value of MS falls below the present target limit of 10 kPa from 1.5% HT onwards, and thus becomes softer and more mobile. MS becomes softer and more mobile from a concentration of 3% onwards.

[0220] At equal concentrations of transport agent, here 3%, all MS have the same plateau value of about 6 kPa.

[0221] When the concentration of the transfer agent is between 1.5% and less than 6%, the compressibility of MS makes them suitable for injection through a microcatheter.

[0222] Example 7: Injection of microspheres from Example 1 in a microcatheter Each of the MS from batches 1 to 9 and L9 was injected through a 4 Fr and a 5 Fr microcatheter. No occlusions were observed.

[0223] In the case of batch 7 (6% HT), the MS did not tolerate preparation for injection and all were destroyed. Thus, the mechanical properties of the MS obtained with 6% transfer agent are not compatible with injection through a microcatheter.

[0224] Example 8: Synthesis by direct suspension polymerization of microspheres (100-300 μm) intended to be loaded according to the invention The aqueous solution of hydrolyzed polyvinyl alcohol and sodium chloride is poured into a reactor and heated to 50°C. An organic phase containing poly(ethylene glycol) methyl ether methacrylate (m-PEGMA) (hydrophilic monomer), poly(ethylene glycol) dimethacrylate (PEGDMA) (crosslinker), methacrylic acid (MA) (ionizable monomer), hexanethiol (HT) (transfer agent), violet dye (1-(4-((2-methacryloxyethyl)oxy)phenylamino)anthraquinone), a suspension of iron nanoparticles, and AIBN (initiator) dissolved in toluene is then fed to the reactor. Agitation is applied using a propeller-type stirrer at a speed suitable to obtain droplets of the desired diameter. The temperature is then increased to 80°C and agitation is continued for 8 hours. The mixture is then filtered and the microspheres are washed with acetone and then with water before being sieved and then autoclaved.

[0225] Table 2 below presents the main parameters and compositions of the organic and aqueous phases.

[0226] [Table 2]

[0227] Example 8-2: Synthesis of microspheres (MS) (900-1200 μm) without ionizable monomers according to the present invention by direct suspension polymerization and evaluation of loading capacity Synthesis of 900-1200 μm microspheres The aqueous solution of hydrolyzed polyvinyl alcohol and sodium chloride is poured into a reactor and heated to 50°C. An organic phase containing poly(ethylene glycol) methyl ether methacrylate (m-PEGMA) (hydrophilic monomer), poly(ethylene glycol) dimethacrylate (PEGDMA) (crosslinker), coloring monomer, hexanethiol (transfer agent) and AIBN (initiator) dissolved in toluene is then fed to the reactor. Agitation is applied using a propeller-type stirrer at a speed suitable to obtain droplets of the desired diameter. The temperature is then increased to 80°C and agitation is continued for 12 hours. The mixture is then filtered through a 40 μm sieve to collect the microspheres. The microspheres retained by the sieve are then washed three times with acetone and then three times with water. These washed microspheres are then sieved between a 900 μm sieve and a 710 μm sieve. The microspheres collected between these two sieves are then sterilized in an autoclave at 121°C for 20 minutes, which has the effect of swelling the microspheres and obtaining microspheres of the desired size, i.e., in this case 900-1200 μm. The microspheres synthesized by the above method then have the following composition:

[0228] Table 3 below presents the main parameters and compositions of the organic and aqueous phases.

[0229] [Table 3]

[0230] Characterization: The dry extract (dry weight) is determined as follows: 1 ml of the deposited MS is placed in a 5 ml Eppendorf vial, frozen at -80°C, and freeze-dried overnight in a freeze-dryer (Heto PowerDry® LL1500, Thermo Scientific). The weight of the microspheres after freeze-drying is then measured. The measurement is performed on three samples, and the average value is taken as the final value of the dry mass of MS.

[0231] The average diameter is determined by analysis of microscopic images of 2000 microspheres (Morphologi 4, Malvern).

[0232] The injectability test in the microcatheter is carried out with a 1 mL deposit of microspheres pre-suspended in 10 mL of iodized contrast medium (70% Optiray® 300, Guerbet, 30% normal saline). The homogeneous suspension of microspheres in a 3 mL syringe is then injected with the microcatheter. Microcatheters supplied by Terumo are selected, with their internal diameter just slightly larger than the average diameter of the microspheres. The resistance felt during the injection of the microspheres with the microcatheter is recorded (Table 3-2). Any blockage during the injection indicates a failed injection. After the injection, the microspheres are observed under a microscope to verify whether they regain their spherical shape.

[0233] [Table 3-2]

[0234] Additionally, 100-300 μm microspheres are synthesized without methacrylic acid (same composition as the microspheres in Example 8 with 0% methacrylic acid (MA) and 94.96% m-PEGMA) and then sterilized by autoclaving. Their capacity for loading doxorubicin is evaluated and compared with that of the microspheres as synthesized according to Example 8.

[0235] Doxorubicin loading: The loading target is 37.5 mg doxorubicin per ml microspheres. For this, 3.8 ml of doxorubicin-HCl (Adriblastine®, Pfizer) at 2.5 mg / ml in water solution are added to 250 μl of wet deposit of microspheres. After mixing by inversion, the suspension is made up to 6 mM with sodium bicarbonate (Lavoisier). The loading is carried out at room temperature and stirred for 1 hour. Measurement of the residual amount of doxorubicin present in the supernatant (absorbance at 490 nm) serves to determine the amount of drug loaded onto the microspheres.

[0236] [Table 4]

[0237] The efficiency of the load is calculated using the following formula:

number

[0238] The loading efficiency in the absence of methacrylic acid is 82.6% compared to 99.6% in the presence of 30% methacrylic acid. The capacity of the microspheres in the absence of ionizable monomers for loading doxorubicin can be explained by the establishment of hydrophobic or van der Waals bonds. In the presence of ionizable monomers, apart from these bonds, doxorubicin is loaded by electrostatic bonds, thereby improving the kinetics and loading capacity.

[0239] Example 9: Synthesis of polymer containing 5% MAOETIB according to the present invention in the form of microspheres with sizes of 700-900 μm by direct suspension polymerization The aqueous solution of hydrolyzed polyvinyl alcohol and sodium chloride is poured into a reactor and heated to 50°C. An organic phase containing poly(ethylene glycol) methyl ether methacrylate (m-PEGMA) (hydrophilic monomer), poly(ethylene glycol) dimethacrylate (PEGDMA) (crosslinker), methacrylic acid (MA) (ionizable monomer), MAOETIB (halogenated monomer), hexanethiol (transfer agent), violet dye (1-(4-((2-methacryloxyethyl)oxy)phenylamino)anthraquinone) and AIBN (initiator) dissolved in toluene is then fed to the reactor. Agitation is applied using a propeller type stirrer at a speed suitable to obtain droplets of the desired diameter. The temperature is then increased to 80°C and agitation is continued for 12 hours. The mixture is then filtered and the microspheres are washed with acetone and then with water before being sieved and then autoclaved.

[0240] Table 5 below presents the main parameters and composition of the organic phase.

[0241] [Table 5]

[0242] Example 10: Suspension of microspheres from Example 9 in a 50 / 50 mixture of contrast agent and normal saline and comparison with the corresponding microspheres in the absence of MAOETIB Add 2 mL of the bead deposit to 10 mL of a 50 / 50 normal saline / contrast mixture (5 mL Optiray® 300 mgl / mL and 5 mL normal saline). Using a 20 mL syringe, pass the mixture through the 3-way stopcock 5 times.

[0243] The syringe containing the mixture is then positioned vertically and the destabilization of the mixture is observed; the microspheres are then allowed to rise to the surface. The time corresponding to when the destabilization interface reaches the mid-height of the syringe is measured.

[0244] For particles with a size of 700-900 μm without MAOETIB, this time is 20 seconds, while for particles containing 5% MAOETIB, it is 120 seconds. This destabilization time further increases to 220 seconds when 7% MAOETIB is added.

[0245] The presence of MAOETIB makes it possible to stabilize the suspension.

[0246] Example 11: Synthesis of various kinds of polymers in the form of microspheres with sizes ranging from 700 to 900 μm by direct suspension polymerization synthesis The aqueous solution of hydrolyzed polyvinyl alcohol and sodium chloride is poured into a reactor and heated to 50°C. An organic phase containing hydrophilic monomers, crosslinking agents, coloring monomers, transfer agents, halogenated monomers if applicable, ionizable monomers if applicable, and AIBN (initiator) dissolved in toluene is then fed to the reactor. Agitation is applied using a propeller-type stirrer at a speed suitable to obtain droplets of the desired diameter. The temperature is then increased to 80°C and agitation is continued for 12 hours. The mixture is then filtered through a 40 μm sieve and the microspheres are collected. The microspheres retained by the sieve are then washed three times with acetone and then three times with water. These washed microspheres are then sieved between a 900 μm sieve and a 710 μm sieve. The microspheres collected between these two sieves are then sterilized in an autoclave at 121°C for 20 minutes, which has the effect of swelling the microspheres and obtaining microspheres of the desired size, i.e., in this case 700-900 μm. Table 6 below presents the main parameters and composition of the organic phase.

[0247] [Table 6]

[0248] Characterization and Results: Characterization was performed as in Example 8-2 and the results are presented in Table 7.

[0249] [Table 7]

[0250] Example 12: Synthesis of polymers containing different amounts of MAOETIB according to the present invention in the form of microspheres with sizes ranging from 100 to 300 μm by direct suspension polymerization Synthesis: The aqueous solution of hydrolyzed polyvinyl alcohol and sodium chloride is poured into a reactor and heated to 50°C. An organic phase containing poly(ethylene glycol) methyl ether methacrylate (m-PEGMA) (hydrophilic monomer), poly(ethylene glycol) dimethacrylate (PEGDMA) (crosslinker), methacrylic acid (MA) (ionizable monomer), MAOETIB (halogenated monomer), hexanethiol (transfer agent), violet dye (1-(4-((2-methacryloxyethyl)oxy)phenylamino)anthraquinone) and AIBN (initiator) dissolved in toluene is then fed to the reactor. Agitation is applied using a propeller type stirrer at a speed suitable to obtain droplets of the desired diameter. The temperature is then increased to 80°C and agitation is continued for 12 hours. The mixture is then filtered and the microspheres are washed with acetone and then with water before being sieved and then autoclaved.

[0251] Table 8 below presents the main parameters and composition of the organic phase.

[0252] [Table 8]

[0253] Example 13: Suspension of microspheres from Example 12 with different levels of MAOETIB in a 50 / 50 mixture of contrast agent and normal saline 2 mL of the bead sediment is added to 10 mL of a 50 / 50 normal saline / contrast mixture (5 mL of Xenetix® 350 mgl / mL and 5 mL of normal saline). Using a 20 mL syringe, the mixture is passed through the three-way stopcock 5 times. The syringe containing the mixture is then positioned vertically and the destabilization of the mixture is observed, either through bubbling or sedimentation, depending on the concentration of MAOETIB. The time corresponding to when the destabilization interface reaches the mid-height of the syringe is measured. The results are presented in Table 9.

[0254] [Table 9]

[0255] The addition of small amounts of MAOETIB makes it possible to retard foaming by bringing the density of the microspheres closer to that of the suspending medium, but above a certain concentration the microspheres become too dense and they sediment rapidly. The present disclosure includes, for example, the embodiments described in the following sections. Section 1. A crosslinked polymer matrix comprising at least: a) N-vinylpyrrolidone, and a compound of formula (I): (CH 2 =CR 1 )-CO-D (I) (In the formula, D represents OZ or NH-Z, and Z represents (C 1 ~C 6 ) alkyl, -(CR 2 R 3 ) m -CH 3 , -(CH 2 -CH 2 -O) m -H, -(CH 2 -CH 2 -O) m -CH 3 , -C(R 4 OH)m or -(CH 2 ) m -NR 5 R 6 where m is an integer from 1 to 30; ·R 1 、R 2 、R 3 、R 4 、R 5 and R 6 are each independently H or (C 1 ~C 6 ) represents alkyl 20% to 95% of hydrophilic monomers selected from the monomers b) a compound of formula (IIa) or (IIb): (CH 2 =(CR 7 ))CO-NH-A-HN-OC(CR 8 =CH 2 ) (IIa), (CH 2 =(CR 7 ))CO-OAO-OC(CR 8 =CH 2 ) (IIb) (In the formula, R 7 and R 8 are each independently H or (C 1 ~C 6 ) alkyl; and A alone or together with at least one of the atoms to which it is bonded is (C 1 ~C 6 ) alkylene, polyethylene glycol (PEG), polysiloxane, poly(dimethylsiloxane) (PDMS), polyglycerol ester (PGE), or bisphenol A. 1% to 15% of a non-biodegradable linear or branched hydrophilic cross-linking monomer, and c) 1.5% to less than 6% of transfer agents selected from alkyl halides and cycloaliphatic or aliphatic thiols, in particular having from 2 to 24 carbon atoms and, optionally, further functional groups selected from amino, hydroxy and carboxy groups. wherein the percentages of monomers a) and b) are given in moles relative to the total number of moles of monomers, and the percentage of compound c) is given in moles relative to the number of moles of hydrophilic monomer a). Section 2. The non-biodegradable embolic microspheres according to item 1, wherein the crosslinked matrix is ​​based on 1.5% to 4.5%, preferably 1.5% to 3%, more preferably 3% of a transfer agent in molar terms compared to the number of moles of the hydrophilic monomer a). Section 3. The non-biodegradable embolic microsphere according to any one of items 1 to 2, wherein the hydrophilic monomer a) is selected from the group consisting of N-vinylpyrrolidone, vinyl alcohol, 2-hydroxyethyl methacrylate, sec-butyl acrylate, n-butyl acrylate, t-butyl acrylate, t-butyl methacrylate, methyl methacrylate, N-dimethylaminoethyl (methyl)acrylate, N,N-dimethylaminopropyl (meth)acrylate, t-butylaminoethyl (methyl)acrylate, N,N-diethylaminoacrylate, poly(ethylene oxide) (meth)acrylate, methoxypoly(ethylene oxide) (meth)acrylate, butoxypoly(ethylene oxide) (meth)acrylate, poly(ethylene glycol) (meth)acrylate, methoxypoly(ethylene glycol) (meth)acrylate, butoxypoly(ethylene glycol) (meth)acrylate and mixtures thereof, and preferably the monomer a) is poly(ethylene glycol) methyl ether methacrylate. Section 4. Item 4. The non-biodegradable embolic microsphere according to any one of items 1 to 3, wherein the transfer agent is selected from the group consisting of thioglycolic acid, 2-mercaptoethanol, dodecanethiol, hexanethiol, and mixtures thereof. Section 5. The matrix may further comprise the following formula (II): (CH 2 =CR 9 )-ME (III) (In the formula, ·R 9 is H or (C 1 ~C 6 ) alkyl; M represents a single bond or a divalent radical having 1 to 20 carbon atoms, preferably a single bond; E represents an ionizable or ionizable group, E is preferably COOH, COO - , S.O. 3 H, SO 3 - , P.O. 4 H 2 , P.O. 4 H - , P.O. 4 2- , N.R. 10 R 11 , N.R. 12 R 13 R 14 + is selected from the group consisting of ·R 10 、R 11 、R 12 、R 13 and R 14 are each independently H or (C 1 ~C 6 ) represents alkyl Item 5. The non-biodegradable embolic microsphere according to any one of items 1 to 4, which is based on at least one ionized or ionizable monomer. Section 6. Item 6. Non-biodegradable embolic microspheres according to item 5, loaded with a drug, an active substance, a diagnostic agent or a macromolecule, said drug, said active substance and said diagnostic agent advantageously having a molecular weight of less than 5000 Da, preferably less than 1000 Da. Section 7. Item 7. The non-biodegradable embolization microspheres comprising a crosslinked matrix according to item 6, wherein the drug or active substance is selected from the group consisting of anti-inflammatory agents, local anesthetics, analgesics, antibiotics, anticancer drugs, steroids, disinfectants and mixtures thereof. Section 8. The polymer may be an enzyme, an antibody, for example, anti-PD-1 such as nivolumab or pembrolizumab, anti-PD-L1 such as avelumab, durvalumab, or atezolizumab, anti-CTLA-4 such as ipilimumab or tremelimumab, a cytokine, a growth factor, a clotting factor, a hormone, a plasmid, an antisense oligonucleotide, an siRNA, a ribozyme, a DNA enzyme, an aptamer, an anti-inflammatory protein such as infliximab and rilonacept, an angiogenesis promoting factor such as bone morphogenetic protein (BMP), fibroblast growth factor (FGF), vascular endothelial growth factor (VEGF), TGF Item 7. The non-biodegradable embolic microspheres according to item 6, wherein the non-biodegradable embolic microspheres are selected from the group consisting of beta, and angiogenesis inhibitors such as bevacizumab, ramucirumab, nesvacumab, olaratumab, vanucizumab, rilotumumab, emibetuzumab, aflibercept, ficlatuzumab, and pegaptanib, or anti-tyrosine kinases such as lenvatinib, sorafenib, sunitinib, pazopanib, vandetanib, axitinib, regorafenib, cabozantinib, fruquintinib, nintedanib, anlotinib, motesanib, cediranib, surufatinib, dovitinib, and linifanib, and mixtures thereof. Section 9. The matrix may further comprise the following general formula (V):

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Claims

1. at least: a) 45% to 95% of a hydrophilic monomer selected from N-vinylpyrrolidone and poly(ethylene glycol) methyl ether methacrylate b) a compound of formula (IIa) or (IIb): (CH ２ =(CR ７ ))CO-NH-A-HN-OC(CR ８ =CH ２ ) (IIa)、(CH ２ =(CR ７ ))CO-O-A-O-OC(CR ８ =CH ２ ) (IIb) (In the formula, R ７ and R ８ are each independently H or (C １ ~C ６ ) alkyl; and A alone or together with at least one of the atoms to which it is attached is (C １ ~C ６ ) 2% to 7% of non-biodegradable linear or branched hydrophilic cross-linking monomers, which represent alkylene, or polyethylene glycol (PEG) having a length in the range of 200 to 10000 g / mol; and c) 1.5% to less than 4.5% of transfer agents selected from alkyl halides and alicyclic or aliphatic thiols having 2 to 24 carbon atoms and optionally further having additional functional groups selected from amino, hydroxy and carboxy groups. A non-biodegradable embolic microsphere comprising a crosslinked matrix based on A non-biodegradable embolic microsphere, wherein the percentages of monomers a) and b) are given in moles relative to the total number of moles of monomers, and the percentage of compound c) is given in moles relative to the number of moles of hydrophilic monomer a).

2. 2. The non-biodegradable embolic microsphere of claim 1, wherein the crosslinked matrix is ​​based on 1.5% to 3% of transfer agent on a molar basis compared to the number of moles of the hydrophilic monomer a).

3. The non-biodegradable embolic microsphere according to any one of claims 1 to 2, wherein the hydrophilic monomer a) is poly(ethylene glycol) methyl ether methacrylate.

4. The non-biodegradable embolic microsphere of any one of claims 1 to 3, wherein the migration agent is selected from thioglycolic acid, 2-mercaptoethanol, dodecanethiol, hexanethiol, and mixtures thereof.

5. The matrix may further comprise the following formula (III): (CH ２ =CR ９ )-M-E (III) (In the formula, ・R ９ is H or (C １ ~C ６ ) alkyl; M represents a single bond or a divalent radical having 1 to 20 carbon atoms; E represents an ionizable or ionizable group. The non-biodegradable embolic microsphere according to any one of claims 1 to 4, which is based on at least one ionized or ionizable monomer of the formula:

6. E is COOH, COO － , S.O. ３ H, SO ３ － , P.O. ４ H ２ , P.O. ４ H － , P.O. ４ ２－ , N.R. １０ R １１ , and N.R. １２ R １３ R １４ ＋ is selected from the group consisting of R １０ , R １１ , R １２ , R １３ and R １４ are each independently H or (C １ ~C ６ 6. The non-biodegradable embolic microsphere of claim 5, wherein R represents an alkyl radical.

7. 7. The non-biodegradable embolic microsphere of claim 5 or 6, which is loaded with a drug, active agent, diagnostic agent or macromolecule having a molecular weight of less than 5000 Da.

8. The non-biodegradable embolic microsphere comprising a crosslinked matrix of claim 7, wherein the drug or active substance is selected from the group consisting of anti-inflammatory agents, local anesthetics, analgesics, antibiotics, anticancer agents, steroids, disinfectants and mixtures thereof.

9. The non-biodegradable embolic microsphere of claim 7, wherein the macromolecule is selected from the group consisting of enzymes, antibodies, cytokines, growth factors, clotting factors, hormones, plasmids, antisense oligonucleotides, siRNA, ribozymes, DNA enzymes, aptamers, anti-inflammatory proteins, bone morphogenetic proteins (BMPs), angiogenesis promoters, vascular endothelial growth factor (VEGF), TGFβ, angiogenesis inhibitors, and anti-tyrosine kinases, and mixtures thereof.

10. The non-biodegradable embolic microsphere of claim 9, wherein the antibody is at least one selected from the group consisting of an anti-PD-1 antibody, an anti-PD-L1 antibody, and an anti-CTLA-4 antibody.

11. The polymer is Nivolumab, pembrolizumab, avelumab, durvalumab, atezolizumab, ipilimumab, tremelimumab, infliximab, rilonacept, fibroblast growth factor (FGF), bevacizumab, ramucirumab, nesvacumab, olaratumab, vanucizumab, rilotumumab, emibetuzumab, aflibercept, ficlatuzumab, pegaptanib, The non-biodegradable embolic microsphere according to claim 9, which is at least one selected from the group consisting of lenvatinib, sorafenib, sunitinib, pazopanib, vandetanib, axitinib, regorafenib, cabozantinib, fruquintinib, nintedanib, anlotinib, motesanib, cediranib, surufatinib, dovitinib, and linifanib.

12. The matrix may further comprise the following general formula (V): 【Chemistry 1】 (In the formula, Z １ and Z ２ are each independently H or OR ２６ represents R ２６ is H or (C １ ~C ６ ) alkyl; X represents H or a halogen; ・R ２４ is linear or branched, (C １ ~C ６ ) alkylene, (C ５ ~C ３６ ) arylene, (C ５ ~C １８ ) Arylene-O-R ２７ , (C ５ ~C １８ ) heteroarylene and (C ５ ~C １８ ) Heteroarylene-O-R ２８ R represents a group selected from ２７ and R ２８ (C １ ~C ６ ) alkyl or (C １ ~C ６ ) alkylene; ・R ２５ is H or (C １ ~C ６ ) represents alkyl The non-biodegradable embolic microsphere according to any one of claims 1 to 11, based on at least one coloured monomer of the formula:

13. The coloring monomer has the formula (Vb): 【Chemistry 2】 The non-biodegradable embolic microsphere of claim 12, which corresponds to:

14. The non-biodegradable embolic microsphere of any one of claims 1 to 13, wherein the matrix is ​​further based on 5% to 15% halogenated monomer, the percentage of halogenated monomer being given in moles as compared to the total number of moles of monomer.

15. The halogenated monomer has formula (IV): (CH ２ =CR １５ )-CO-Y (IV) (In the formula, ・Y is O-W, (O-R １６ ) ｐ -W, (NH-R １６ ) ｐ —W or NH—W, W represents Ar, L-Ar, and p is an integer from 1 to 10, where: Ar is (C ５ ~C ３６ ) an aryl group or (C ５ ~C ３６ ) heteroaryl groups, which are substituted with one, two or three iodine and / or bromine atoms, and further represented by (C １ ~C １０ ) alkyl, -NR ａ R ｂ , -NR ｃ C.O.R. ｄ , -COOR ｅ , -OR ｆ , -OCOR ｇ , -CONR ｈ R ｉ , -OCONR ｊ R ｋ , -NR ｌ COOR ｏ , -N ｒ C.O.N.R. ｓ R ｔ , -OCOOR ｕ , and -COR ｖ may be substituted with 1 to 4 groups selected from L is -(CH ２ ) ｎ -, - (HCCH) ｎ -, -O-, -S-, -SO-, -SO ２ --, --OSO ２ － , -NR １７ -, -CO-, -COO-, -OCO-, -OCOO-, -CONR １８ --, --NR １９ CO-, -OCONR ２０ --, --NR ２１ COO- or -NR ２２ C.O.N.R. ２３ -, where n is an integer from 1 to 10; ・R １７ ~R ２３ and R ａ ~R ｖ are each independently a hydrogen atom, (C １ ~C １０ ) alkyl, １ ~C １０ ) alkyl is 1 to 10 OR′ groups or —(CH ２ -CH ２ -O) ｑ may be substituted with a -R' group, where R' is a hydrogen atom or -(C １ ~C ６ ) alkyl, and q is an integer from 1 to 10; ・R １５ is H or (C １ ~C ６ ) alkyl; ・R １６ (C １ ~C ３６ ) alkylene, (C ３ ~C ３６ ) cycloalkylene, (C ２ ~C ３６ ) alkenylene, (C ３ ~C ３６ ) cycloalkenylene, (C ２ ~C ３６ ) alkynylene, (C ３ ~C ３６ ) cycloalkynylene, (C ５ ~C ３６ ) arylene and (C ５ ~C ３６ ) heteroarylene) The non-biodegradable embolic microsphere of claim 14, wherein the halogenated monomer is represented by the formula:

16. The halogenated monomer has the following formula: 【Chemistry 3】 15. A non-biodegradable embolic microsphere comprising a crosslinked matrix comprising at least one halogenated monomer according to claim 14, which corresponds to (triiodobenzoyl)oxoethyl methacrylate (MAOETIB).

17. 17. A non-biodegradable embolic microsphere comprising a crosslinked matrix according to any one of claims 1 to 16, wherein the matrix is ​​further based on particles that are visible by magnetic resonance imaging (MRI).

18. 18. The non-biodegradable embolic microsphere of claim 17, wherein the magnetic resonance imaging (MRI) visible particles are iron oxide nanoparticles, gadolinium chelates or magnesium chelates.

19. A pharmaceutical composition comprising the non-biodegradable embolic microspheres of any one of claims 1 to 18, in association with a pharma- ceutically acceptable vehicle.

20. 20. A kit comprising a pharmaceutical composition as defined in claim 19, together with a pharma- ceutically acceptable vehicle intended for parenteral administration, and at least one injection means.

21. 20. A kit comprising on the one hand a pharmaceutical composition as defined in claim 19 and on the other hand at least one contrast agent for imaging by X-ray, magnetic resonance or ultrasound, and optionally further comprising at least one injection means intended for parenteral administration, wherein said pharmaceutical composition and said at least one contrast agent are packaged separately.

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