Iodinated cross-linked hydrogels and methods for forming same

Abstract

Iodinated cross-linked hydrogels and methods for forming the same are provided. In some aspects, the present disclosure relates to a system for forming a hydrogel comprising (a) an iodinated polyamino compound and (b) a reactive multi-arm polymer comprising a plurality of hydrophilic polymer arms having unsaturated end groups reactive with the amino groups of the iodinated polyamino compound. Another aspect of the disclosure relates to a medical hydrogel formed by crosslinking the iodinated polyamino compound and the reactive multi-arm polymer of such a system. A further aspect of the disclosure relates to a medical procedure that can be performed using such a system.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 398,765, filed August 17, 2022, the disclosure of which is incorporated herein by reference. Among other aspects, the present disclosure relates to iodinated crosslinked hydrogels, as well as methods of making and using iodinated compounds and hydrogels. The iodinated crosslinked hydrogels of the present disclosure are useful, for example, in a variety of biomedical applications. [Background technology]

[0002] In vivo cross-linked hydrogels based on star-poly(ethylene glycol) (star-PEG) polymers functionalized with reactive ester end groups that react with lysine trimer (Lys-Lys-Lys) as a cross-linker to rapidly form cross-linked hydrogels, such as SpaceOAR®, have become clinically important materials as adjuvants in radiation therapy. Augmenix Announces Positive Three-Year SpaceOAR (R) See “Clinical Trial Results,” Imaging Technology News, October 27, 2016. Hydrogels have also been developed in which some of the star-PEG branches are functionalized with 2,3,5-triiodobenzamide (TIB) groups and some of the ester end groups are substituted, such as SpaceOAR® Vue, which enhances radiation contrast. Augmenix Receives FDA Clearance to Market its TraceIT (R) See "Tissue Marker," BusinessWire Jan. 28, 2013. TraceIT® hydrogel remains stable and visible in tissue for three months, sufficient time for radiation therapy, after which it is absorbed and eliminated from the body. Id.

[0003] While the above approach is effective, incorporating the TIB functional group presents several challenges. First, TIB has poor water solubility, which impacts the number of TIB groups that can be added to a PEG arm before affecting its ability to form a smooth, uniform hydrogel. Furthermore, the overall functionalization process requires multiple steps to transition from commercially available hydroxyl-terminated 8-arm PEG to a functionalized form with two distinct end groups (i.e., TIB and succinimidyl glutarate (SG) groups). This complicates the star PEG manufacturing process, significantly increasing product costs and making product quality difficult to control. Finally, functionalizing hydrogels with iodine using star polymer arms results in fewer arms available for crosslinking. This can be resolved by adding more polymer, but this increases the solids content and may adversely affect viscosity. Lowering the molecular weight can reduce the solids content, but this lowers the melting point, significantly impacting storage and transportation conditions and creating processability challenges. An additional impact of lowering the crosslink density per star polymer is a slower setting rate for the resulting gel. This means that the gels remain liquid and mobile in vivo for longer periods, creating opportunities for unintended side reactions and material substitution. Finally, star PEGs labeled with TIB end groups often exhibit discoloration due to thermal degradation. While this does not affect functionality, it is a cosmetic defect that is preferably avoided. For these reasons, innovative strategies for iodine-labeled crosslinkable hydrogels are desirable.

[0004] The present disclosure relates to an alternative approach. Rather than using the arms of a star polymer to functionalize the hydrogel with iodine, the crosslinker of the star polymer is functionalized with iodine. Furthermore, the use of reactive succinimidyl glutarate groups on the star polymer can be avoided. Summary of the Invention

[0005] In some aspects, the present disclosure relates to a system for forming a hydrogel comprising: (a) an iodinated polyamino compound; and (b) a reactive multi-arm polymer comprising a plurality of hydrophilic polymer arms having unsaturated end groups reactive with the amino groups of the iodinated polyamino compound. In some of these embodiments, the iodinated polyamino compound comprises a polyamino moiety linked by an amide group to a carboxy-substituted iodinated moiety. In some of these embodiments, the carboxy-substituted iodinated moiety comprises an iodinated group, such as an iodinated aromatic group, and a carboxylic acid or carboxylate group. In some of these embodiments, the carboxy-substituted iodinated moiety is an iodinated amino acid residue. In some of these embodiments, the polyamino moiety comprises a plurality of —(CH) x It comprises an —NH 2 group, and x is 0, 1, 2, 3, 4, 5, or 6. In some of these embodiments, the polyamino moiety comprises two or more amino acid residues selected from residues of lysine, ornithine, and combinations thereof.

[0006] In some embodiments that can be used in combination with the above aspects and embodiments, the unsaturated end groups are selected from acrylate ester groups and propiolate ester groups. In some embodiments that can be used in combination with the above aspects and embodiments, the hydrophilic polymer arms comprise one or more hydrophilic monomers selected from ethylene oxide, N-vinylpyrrolidone, oxazoline, hydroxyethyl acrylate, hydroxyethyl methacrylate, PEG methyl ether acrylate or PEG methyl ether methacrylate, or PNIPAAM. In some embodiments that can be used in combination with the above aspects and embodiments, the unsaturated end group is attached to the hydrophilic polymer arm by a hydrolyzable ester group, such as a glutarate group, a succinate group, a carbonate group, or an adipate group. In some embodiments that can be used in combination with the above aspects and embodiments, a system includes a first precursor composition comprising an iodinated polyamino compound, a second precursor composition comprising a reactive multi-arm polymer, and an optional accelerator composition. In some of these embodiments, the first precursor composition is provided in a syringe barrel, the second precursor composition is provided in a vial, and the accelerator composition is provided in the syringe barrel. In some embodiments that can be used in combination with the above aspects and embodiments, the system further comprises a delivery device.

[0007] In another aspect, the present disclosure relates to a medical hydrogel formed by crosslinking the iodinated polyamino compound and the reactive multi-arm polymer of the system of any of the above aspects and embodiments under conditions such that a medical hydrogel is formed. For example, the medical hydrogel may be, among other things, a medical implant or a medical device coating. In another aspect, the present disclosure relates to a method of treatment comprising administering to a subject a mixture comprising an iodinated polyamino compound and a reactive multi-arm polymer comprising a plurality of hydrophilic polymer arms having unsaturated end groups reactive with amino groups of the iodinated polyamino compound, e.g., according to any of the above aspects and embodiments, under conditions such that the iodinated polyamino compound and the reactive multi-arm polymer crosslink after administration.

[0008] Potential advantages associated with the present disclosure include one or more of the following: maintaining radiation contrast; reducing the complexity and cost of the manufacturing process; maintaining the melting point of the solid components of the hydrogel above 40°C (improving storage and handling); improving the homogeneity of the final hydrogel; providing biopersistence; and maintaining the cure rate. These and other aspects, embodiments, features, and advantages of the present disclosure will become readily apparent from the following detailed description. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating a method for crosslinking a reactive multi-arm polymer comprising a core region and a plurality of hydrophilic polymer arms having acrylate end groups with an iodinated polyamino compound according to one aspect of the present disclosure. [Figure 2A] 1 is a chemical diagram of an iodinated polyamino compound that can be used as a crosslinker according to three embodiments of the present disclosure. [Figure 2B] 1 is a chemical diagram of an iodinated polyamino compound that can be used as a crosslinker according to three embodiments of the present disclosure. [Figure 2C] 1 is a chemical diagram of an iodinated polyamino compound that can be used as a crosslinker according to three embodiments of the present disclosure. [Figure 3A] 1 is a chemical diagram of an iodinated polyamino compound that can be used as a crosslinker according to three further embodiments of the present disclosure. [Figure 3B] 1 is a chemical diagram of an iodinated polyamino compound that can be used as a crosslinker according to three further embodiments of the present disclosure. [Figure 3C] 1 is a chemical diagram of an iodinated polyamino compound that can be used as a crosslinker according to three further embodiments of the present disclosure. [Figure 4] FIG. 1 is a schematic diagram illustrating a method for producing a reactive multi-arm polymer comprising a core region and a plurality of polyethylene oxide (PEO) arms having acrylate end groups by reacting acryloyl chloride with a multi-arm polymer having a core region comprising a polyol residue and eight hydroxyl-terminated polyethylene oxide arms, according to one embodiment of the present disclosure. [Figure 5] FIG. 1 shows a schematic diagram of a method for coupling an iodinated amino acid compound to trilysine to form an iodinated peptide sequence, according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] In some aspects of the present disclosure, there is provided a radiopaque crosslinked hydrogel comprising the crosslinked reaction product of (a) an iodinated polyamino compound and (b) a reactive multi-arm polymer comprising multiple unsaturated end groups reactive with the amino groups of the iodinated polyamino compound. Unless otherwise indicated, as used herein, the prefix "poly" means two or more. In some aspects of the present disclosure, systems are provided that are configured to dispense an iodinated polyamino compound and a reactive multi-arm polymer comprising multiple unsaturated end groups under conditions such that the iodinated polyamino compound and the reactive multi-arm polymer crosslink with each other. In certain embodiments, these conditions include an environment having a basic pH, e.g., a pH in the range of about 9 to about 11, typically about 9.5 to about 10.5, and advantageously about 9.8 to about 10.2.

[0011] In some aspects of the present disclosure, a system is provided that includes (a) a first composition comprising an iodinated polyamino compound and (b) a second composition comprising a reactive multi-arm polymer comprising a plurality of unsaturated end groups reactive with the amino groups of the iodinated polyamino compound. In some embodiments, a third composition in the form of an accelerator composition is provided. Such systems are advantageous in that the iodine functionality, and therefore radiopacity, is provided by, for example, an iodinated polyamino compound that acts as a crosslinker for the multi-arm polymer, thereby providing reactive end groups on each of the polymer arms, thereby maximizing the crosslinking capacity of the multi-arm polymer without sacrificing radiopacity.

[0012] In various embodiments, the unsaturated end groups of the reactive multi-arm polymer and the amino groups of the iodinated polyamino compound react with each other via Michael addition. In certain embodiments, the reaction between the unsaturated end groups and the amino groups is carried out at a slightly basic pH (e.g., pH values ​​in the range of 7.4 to 11), the amino groups of the iodinated polyamino compound are deprotonated / neutralized, and the Michael addition can occur spontaneously at body temperature. Reactive multi-arm polymers for use herein include those containing multiple polymer arms (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or more arms), wherein two or more polymer arms of the multi-arm polymer each contain one or more unsaturated end groups. Examples of unsaturated end groups include acrylate ester groups. [ka] and propiolate ester groups. [ka] and the like.

[0013] In some embodiments, compositions are provided that include reactive multi-arm polymers, wherein the percentage of polymer arms comprising one or more unsaturated end groups can represent 50% to 100% of the total number of polymer arms in the composition (e.g., any range of 50%, 70%, 80%, 90%, 95%, 99%, to 100% of the total number of polymer arms). Typical average molecular weights of reactive multi-arm polymers for use herein range from 10 to 50 kDa, although other values ​​exist. In various embodiments, reactive multi-arm polymers for use herein have a melting point of 40°C or greater, preferably 45°C or greater.

[0014] In various embodiments, the polymer arms are hydrophilic polymer arms. Such hydrophilic polymer arms may be comprised of any of a variety of synthetic, natural, or synthetic-natural hybrid polymers, including, for example, poly(ethylene oxide) (PEO) (also called polyethylene glycol or PEG), poly(alkylene oxide) such as poly(propylene oxide) or poly(ethylene oxide-co-propylene oxide), poly(N-vinylpyrrolidone), polyoxazolines, including poly(2-alkyl-2-oxazolines) such as poly(2-methyl-2-oxazoline), poly(2-ethyl-2-oxazoline), and poly(2-propyl-2-oxazoline), poly(vinyl alcohol), poly(allyl alcohol), polyhydroxyethyl acrylate, polyhydroxyethyl methacrylate, PEG methyl ether acrylate or PEG methyl ether methacrylate, or PNIPAAM, polysaccharides, and combinations thereof.

[0015] In some embodiments, the polymer arms extend from a core region. In certain of these embodiments, the core region comprises the residue of a polyol used to form the polymer arms. Exemplary polyols include, for example, linear, branched, and cyclic aliphatic polyols, including linear, branched, and cyclic polyhydroxyalkanes; linear, branched, and cyclic polyhydroxyethers, including polyhydroxypolyethers; linear, branched, and cyclic polyhydroxyalkylethers, including polyhydroxyalkylpolyethers; linear, branched, and cyclic sugars and sugar alcohols, such as glycerol, mannitol, sorbitol, inositol, xylitol, quebrachitol, threitol, arabitol, erythritol, adonitol, dulcitol, fucose, ribose, arabinose, xylose, lyxose, rhamnose, galactose, glucose, fructose, sorbose, mannolol, and the like. The polyols may be selected from linear, branched, and cyclic sugar and sugar alcohol polymers (defined herein as two or more units), including oligomers (defined herein as ranging from 2 to 10 units, including dimers, trimers, tetramers, pentamers, hexamers, heptamers, octamers, enneamers, and decamers) of linear, branched, and cyclic sugar and sugar alcohols, including sugars, pyranses, altroses, taloses, tagatoses, pyranosides, sucrose, lactose, and maltose, the aforementioned sugars and sugar alcohols, starches, amyloses, dextrins, cyclodextrins, and polyhydroxy crown ethers and polyhydroxyalkyl crown ethers. Exemplary polyols also include aromatic polyols, including 1,1,1-tris(4'-hydroxyphenyl)alkanes, e.g., 1,1,1-tris(4-hydroxyphenyl)ethane, and 2,6-bis(hydroxyalkyl)cresols.

[0016] In certain advantageous embodiments, the core region comprises residues of a polyol that contains 2, 3, 4, 5, 6, 7, 8, 9, 10 or more hydroxyl groups, hi certain advantageous embodiments, the core region comprises residues of a polyol that is an oligomer of a sugar alcohol such as glycerol, mannitol, sorbitol, inositol, xylitol, or erythritol, among others. In certain embodiments, the unsaturated end groups are attached to the polymer arms via hydrolyzable ester groups, which can be chosen from, for example, glutarate, succinate, carbonate, or adipate groups.

[0017] Multi-arm polymers having arms containing one or more unsaturated end groups (e.g., acrylate groups, propiolate groups, etc.) can be formed from multi-arm polymers having arms containing one or more hydroxyl end groups. In one particular embodiment, shown in Figure 4, a reactive multi-arm polymer containing a core region and a plurality of polyethylene oxide (PEO) arms having reactive acrylate end groups is formed by reacting acryloyl chloride with the hydroxyl end groups of a multi-arm polymer having a core region containing a polyol residue R and n hydroxyl-terminated polyethylene oxide arms (n ranging from 30 to 140). In particular, a commercially available 8-arm hydroxyl-terminated polymer in which R is a tripentaerythritol polyol residue is reacted with acryloyl chloride to produce an 8-arm acrylate-terminated PEO. Acrylate-terminated 8-arm PEO with a tripentaerythritol residue core (also called acrylate-terminated 8-arm PEG) and acrylate-terminated 4-arm PEO with a pentaerythritol residue core (also called acrylate-terminated 4-arm PEG) are also available from JenKem Technology USA (Plano, Texas, USA).

[0018] As mentioned above, in various embodiments of the present disclosure, the unsaturated end groups (e.g., acrylate groups, propiolate groups, etc.) of such reactive multi-arm polymers can react with the amino groups of the iodinated polyamino compound via Michael addition to form a crosslinked composition.

[0019] In various embodiments, iodinated polyamino compounds for use in the present disclosure comprise a polyamino moiety attached to a carboxy-substituted iodinated moiety. In certain embodiments, the polyamino moiety is attached to the carboxy-substituted iodinated moiety via an amide group. In certain embodiments, detailed below, the iodinated polyamino compound may comprise a peptide oligomer comprising 2-10 lysine and / or ornithine amino acid residues and one or more iodinated amino acid residues. Carboxy-substituted iodinated moieties of the present disclosure include those comprising an iodinated group and a carboxylic acid or carboxylate group, including anionic carboxylate groups, carboxylic acid amide groups, and carboxylic acid ester groups. In some embodiments, the carboxy-substituted iodinated moieties of the present disclosure include an iodinated aromatic group (also referred to herein as an iodoaromatic group) and a carboxylic acid or carboxylate group. Examples of iodinated aromatic groups include iodine-substituted monocyclic aromatic groups and iodine-substituted polycyclic aromatic groups, such as iodophenyl and iodonaphthyl groups. The aromatic group may be substituted with one, two, three, four, five, six, or more iodine atoms. In certain embodiments, the carboxy-substituted iodinated moieties of the present disclosure comprise at least one hydroxy-iodo-aromatic group and a carboxylic acid or carboxylate group. Examples of hydroxy-iodo-aromatic groups include hydroxy-iodo-phenyl and hydroxy-iodo-naphthyl groups. More specific examples of hydroxy-iodo-aromatic groups include hydroxy-iodo-phenyl groups selected from mono-hydroxy-mono-iodo-phenyl, mono-hydroxy-di-iodo-phenyl, mono-hydroxy-tri-iodo-phenyl, mono-hydroxy-tetra-iodo-phenyl, di-hydroxy-mono-iodo-phenyl, di-hydroxy-di-iodo-phenyl, di-hydroxy-tri-iodo-phenyl, tri-hydroxy-mono-iodo-phenyl, and tri-hydroxy-di-iodo-phenyl groups.

[0020] In some embodiments, the carboxy-substituted iodinated moieties of the present disclosure comprise iodinated amino acid residues. As used herein, an "amino acid" is an organic compound containing an amino group (-NH), a carboxylic acid group (-COOH), and a side chain specific to each amino acid. Depending on the ambient pH, the amino group may be positively charged (-NH + ) and / or the carboxylic acid group may be negatively charged (-COO - Iodinated amino acids are amino acids whose side chains contain one or more iodine atoms. Examples of iodinated amino acid residues include iodinated α-amino acid residues, iodinated β-amino acid residues, iodinated γ-amino acid residues and iodinated δ-amino acid residues.

[0021] Examples of iodinated amino acid residues include amino acid residues containing an iodinated aromatic group. As described above, examples of iodinated aromatic groups include an iodo-phenyl group and an iodo-naphthyl group. In certain embodiments, the iodinated amino acid residue comprises an amino acid residue containing a hydroxy-iodo-aromatic group, such as a hydroxy-iodo-phenyl group or a hydroxy-iodo-naphthyl group. More specific examples of hydroxy-iodo-aromatic groups include, as described above, hydroxy-iodo-phenyl groups selected from mono-hydroxy-mono-iodo-phenyl, mono-hydroxy-di-iodo-phenyl, mono-hydroxy-tri-iodo-phenyl, mono-hydroxy-tetra-iodo-phenyl, di-hydroxy-mono-iodo-phenyl, di-hydroxy-di-iodo-phenyl, di-hydroxy-tri-iodo-phenyl, tri-hydroxy-mono-iodo-phenyl, and tri-hydroxy-di-iodo-phenyl groups.

[0022] Specific examples of iodinated amino acid residues include the following iodinated amino acid residues: iodophenylalanine, which contains a mono-iodo-phenyl group; [ka] monoiodotyrosine, which contains a mono-iodo-phenyl group, specifically a mono-hydroxy-mono-iodo-phenyl group; [ka] diiodotyrosine, which contains a mono-hydroxy-di-iodo-phenyl group; [ka] Diiodothyronine, which contains a di-iodo-phenyl group and a hydroxy-phenyl group; [ka] Triiodothyronine, also known as T3, which contains a di-iodo-phenyl group and a mono-hydroxy-mono-iodo-phenyl group; [ka] Tetraiodothyronine, also known as thyroxine or T4, which contains a di-iodo-phenyl group and a mono-hydroxy-di-iodo-phenyl group; [ka] iodophenylalanine and 6-iodo-L-DOPA, which contains a di-hydroxy-mono-iodo-phenyl group. Many of these iodinated amino acids are relatively water-soluble, and some, such as 3,5-diiodotyrosine and L-thyroxine, have been well studied as monomers for bioerodible polymers.

[0023] As further described below, iodinated polyamino compounds of the present disclosure can be formed by an amide coupling reaction between a carboxyl-substituted polyamino compound (after protection of the amino groups), for example, selected from those described below, and an iodinated amino acid derivative, e.g., a C1-C5 alkyl ester of an iodinated amino acid, preferably a methyl ester of an iodinated amino acid, which effectively serves as a protecting group for the carboxylic acid groups of the final iodinated polyamino compound. Examples of such iodinated amino acid derivatives include C1-C5 alkyl esters of any of the aforementioned iodinated amino acids. After coupling, the protecting group on the residue of the carboxyl-substituted polyamino compound is removed, and the C1-C5 alkyl ester may be converted to the corresponding carboxylic acid or anionic carboxylate group, thereby providing the final iodinated polyamino compound.

[0024] In addition to a carboxy-substituted iodinated moiety such as one of those described above, the iodinated polyamino compounds of the present disclosure also include a polyamino moiety attached to the carboxy-substituted iodinated moiety. In various embodiments, the iodinated polyamino compounds of the present disclosure include a polyamino moiety having a plurality (2, 3, 4, 5, 6, 7, 8, 9, 10 or more) of amino groups. For example, the polyamino moiety may include a plurality (2, 3, 4, 5, 6, 7, 8, 9, 10 or more) of —(CH) x and x is 0, 1, 2, 3, 4, 5, or 6. In some of these embodiments, the polyamino moiety may comprise multiple -(CH) groups disposed along the polymeric portion (defined herein as a portion containing 2, 3, 4, 5, 6, 7, 8, 9, 10, or more monomer residues). x It may contain -NH2 groups. In some embodiments, the polymer moiety may be selected from a polyamide moiety, such as a peptide moiety, a polyalkylene moiety, or a polysaccharide moiety, among others.

[0025] In some embodiments, the polyamino moiety of the iodinated polyamino compound can correspond to the residue of a carboxyl-substituted polyamino compound (a compound containing a carboxyl group and multiple amino groups). Examples of carboxyl-substituted polyamino compounds include peptides containing 2-10 lysine and / or ornithine amino acid residues, including polylysine (e.g., dilysine, trilysine, tetralysine, pentalysine, etc.) and carboxyl-terminated polyamines such as carboxyl-terminated poly(allylamine), carboxyl-terminated poly(vinylamine), or carboxyl-terminated chitosan.

[0026] Commercially available examples of carboxyl-substituted polyamino compounds include 16-amino-3-[2-[(4-aminobutyl)(3-aminopropyl)amino]-2-oxoethyl]-12-(3-aminopropyl)-6,9-bis(carboxymethyl)-11-oxo-3,6,9,12-tetraazahexadecanoic acid, L-ornityl-L-ornithine, N 2 -[1-[N 2 -[N 2-(NL-valyl-L-alanyl)-L-lysyl]-L-lysyl]-L-prolyl]-L-lysine, L-lysyl-L-tryptophyl-L-lysyl-L-lysine, N 2 ,N 5 ,N 5 -Tris(3-aminopropyl)-L-ornithine, L-lysyl-L-ornityl-L-lysine, D-lysyl-D-lysyl-D-lysine, glycylglycyl-L-lysylglycylglycyl-L-lysine, N 2 -[N 4 -[N-[N-(N-glycylglycyl)glycyl]glycyl]-L-lysyl]-L-lysine, L-lysyl-L-threonyl-L-lysyl-L-lysine, glycylglycyl-L-lysyl-L-lysylglycyl-L-cysteine, L-lysyl-L-arginyl-L-lysyl-L-lysine, L-arginyl-L-lysyl-L-lysyl-L-lysine, L-leucyl-L-lysyl-L-seryl-L-lysyl-L-lysine, L-alanyl-L-methionylglycyl-L-lysyl-L-lysine, L-lysyl-L-lysyl-L-lysine, L-lysyl-L-lysyl-L-arginyl-L-glutamine, L-seryl-L-isoleucyl-L-lysyl-L-lysyl-L-lysine, N 2 -(N 2 Also included are (L-ornityl-L-lysyl)-L-lysine, lysyl-lysyl-lysine, and L-lysyl-L-lysyl-L-lysyl-L-alanine.

[0027] As mentioned above, in certain embodiments, the iodinated polyamino compounds of the present disclosure comprise a polyamino moiety linked to a carboxy-substituted iodinated moiety via an amide group. The amide group may be the result of a coupling reaction between the amino group of an iodinated amino acid, such as any of those described above, and the carboxyl group of a carboxyl-substituted polyamino compound, such as any of those described above. The resulting iodinated polyamino compound thus comprises a residue of the carboxyl-substituted polyamino compound and a residue of the iodinated amino acid. In other words, the iodinated polyamino compounds of the present disclosure may be formed by an amidation reaction in which the carboxyl group of a carboxyl-substituted polyamino compound reacts with the amino group of an iodinated amino acid to form an amide bond between the two residues. In some aspects, the present disclosure relates to a process for producing such iodinated polyamino compounds.

[0028] In the first process step, the amino groups of the carboxyl-substituted polyamino compound can be protected with a suitable protecting agent. The amino groups are protected for compatibility with other reactants in the subsequent amide coupling reaction (described below). For example, the amino groups of the carboxyl-substituted polyamino compound can be protected by reaction with di-tert-butyl dicarbonate.

[0029] In a specific example, referring to Figure 4, the amino group of trilysine (110) is protected using di-tert-butyl dicarbonate (CAS No. 24424-99-5), thereby forming tBoc-protected trilysine (112). This makes the carboxyl group of the protected compound (tBoc-protected trilysine) available for amide coupling. In a second step, an iodinated amino acid derivative, specifically an iodinated amino acid C1-C5 alkyl ester, is coupled with the protected carboxyl-substituted polyamino compound formed in the first process step in an amide coupling reaction (e.g., via a carbodiimide coupling reagent) to form a protected iodinated polyamino compound. In a specific example, referring to Figure 4, tBoc-protected trilysine (112) is coupled with an iodinated amino acid derivative (specifically, 3,5-diiodo-L-tyrosine methyl ester (CAS No. 76318-50-8)) in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC-HCl) in dimethylformamide (DMF) to yield the t-Boc-protected iodinated peptide oligomer (t-Boc-Lys-Lys-Lys-Tyr-I2) (114). 3,5-Diiodo-L-tyrosine has been used to improve radiopacity in in vivo biological applications (see, e.g., U.S. Patent Application Publication No. 2019 / 0142863 and U.S. Patent No. 8,288,505). In the third process step, the product of the second process step is deprotected and hydrolyzed (e.g., under acidic conditions) to form the final carboxyl-substituted iodinated polyamino compound. For example, as shown in Figure 4, the t-Boc-protected iodinated peptide segment (t-Boc-Lys-Lys-Lys-Tyr-I2) (114) is deprotected and hydrolyzed under acidic conditions using an acid such as trifluoroacetic acid to form the activated iodinated polyamino compound (Lys-Lys-Lys-Tyr-I2) (116). The above process can be carried out with a variety of carboxyl-substituted polyamino compounds and a variety of iodinated amino acid derivatives. With regard to the latter, when diiodotyrosine methyl ester is coupled to trilysine as described above, the resulting compound is shown in Figure 2A, while when thyroxine methyl ester is coupled to trilysine, the resulting compound is shown in Figure 3A.

[0030] Further, by repeating the first, second, and third processes, more iodinated amino acid groups can be successively added to the chain ends; however, the iodinated polyamino compound formed in the third process displaces the trilysine from the first process step to form a protected compound, which is then coupled with another iodinated amino acid C1-C5 alkyl ester in an amide coupling reaction along the lines of the second process, followed by deprotection and hydrolysis along the lines of the third process. When the iodinated amino acid C1-C5 alkyl ester is diiodotyrosine methyl ester, the result of performing these additional steps once is shown in Figure 2B, which contains two diiodotyrosine residues. When the iodinated amino acid C1-C5 alkyl ester is thyroxine methyl ester, the result of performing these additional steps once is shown in Figure 3B, which contains two thyroxine residues.

[0031] Repeating the first, second, and third processes again using the product of Figure 2B in place of trilysine and diiodotyrosine methyl ester as the iodinated amino acid C1-C5 alkyl ester yields a product containing three diiodotyrosine residues as shown in Figure 2C. Repeating the first, second, and third processes again using the product of Figure 3B in place of trilysine and thyroxine methyl ester as the iodinated amino acid C1-C5 alkyl ester yields a product containing three thyroxine residues as shown in Figure 3C. Additional iodinated amino acid residues can be added, if desired.

[0032] As described above, some aspects of the present disclosure provide radiopaque crosslinked hydrogels comprising the crosslinked reaction product of (a) an iodinated polyamino compound, as described above, and (b) a reactive multi-arm polymer, as described above, having unsaturated end groups and including multiple polymer arms reactive with the amino groups of the iodinated polyamino compound via Michael addition. In one embodiment of the present disclosure, referring to FIG. 1 , an iodinated polyamino compound, specifically, an iodinated peptide oligomer (Lys-Lys-Lys-Tyr-I2) (116) is combined with an acrylate-terminated 8-arm PEG (118) having a pentaerythritol residue core under conditions such that a Michael addition occurs between the acrylate groups of the acrylate-terminated 8-arm PEG (118) and the amino groups of the iodinated peptide oligomer (116), thereby forming a crosslinked hydrogel (120). For example, the Michael addition can proceed in aqueous solution under slightly basic conditions (e.g., in the presence of a buffer such as phosphate-buffered saline (PBS) or a borax-related buffer, in the pH range of 7.4 to 11).

[0033] In various embodiments, the crosslinked hydrogels of the present disclosure are visible under fluoroscopy. In various embodiments, such crosslinked products have a radiopacity of greater than 250 Hounsfield Units (HU), and advantageously have a radiopacity ranging from 250 HU to 500 HU to 750 HU to 1000 HU or more (i.e., a range between any two of the aforementioned values). Such crosslinked products can be formed in vivo (e.g., using a delivery device such as those described below), or they can be formed ex vivo and then administered to a subject. Such crosslinked products can be used in a wide variety of biomedical applications, including medical devices, implants, and pharmaceutical compositions. In various embodiments, the unsaturated end groups of the reactive multi-arm polymer and the amino groups of the iodinated polyamino compound react with each other to form a crosslinked product. In some aspects of the present disclosure, systems are provided that are configured to deliver an iodinated polyamino compound and a reactive multi-arm polymer comprising a plurality of unsaturated end groups reactive with the amino groups of the iodinated polyamino compound under conditions such that the iodinated polyamino compound and the reactive multi-arm polymer crosslink with each other. Such systems can be used to form crosslinked hydrogels either in vivo or ex vivo.

[0034] For example, and referring again to FIG. 1 , a second composition comprising a reactive multi-arm polymer (118) as described above (where R is a core region such as a tripentaerythritol polyol residue and n is 8) comprising a core region and a plurality of hydrophilic polyethylene oxide arms having unsaturated end groups (i.e., acylated end groups) can be crosslinked with a first composition comprising an iodinated polyamino compound (116) as described above comprising amino groups capable of reacting with the unsaturated end groups of the reactive multi-arm polymer (118) to form a crosslinked product (120), which may be in the form of a hydrogel when hydrated. The advantage of this approach is that the iodination is separate from the parent polymer, and the reactive multi-arm polymer having unsaturated end groups can be exchanged for a multi-arm polymer having hydrophilic polymer arms other than polyethylene oxide arms and having unsaturated end groups, for example, a multi-arm polymer having synthetic, natural, or hybrid synthetic-natural hydrophilic polymer arms as described above.

[0035] As mentioned above, some aspects of the present disclosure provide a system comprising: (a) a first composition comprising an iodinated polyamino compound; and (b) a second composition comprising a reactive multi-arm polymer comprising a plurality of unsaturated end groups reactive with the amino groups of the iodinated polyamino compound. The first composition may be a first fluid composition comprising an iodinated polyamino compound, or may be a first dry composition comprising an iodinated polyamino compound to which an appropriate fluid, such as water for injection, saline, or the like, can be added to form the first fluid composition. In addition to the iodinated polyamino compound, the first composition may further comprise a pH adjuster and / or additional agents, as described below. The second composition may be a second fluid composition comprising the reactive multi-arm polymer, or may be a second dry composition comprising the reactive multi-arm polymer to which a suitable fluid, such as water for injection, saline, etc., can be added to form the second fluid composition. In addition to the reactive multi-arm polymer, the second composition may further comprise a pH adjuster and / or additional agents, as described below.

[0036] In some embodiments, the iodinated polyamino compound is first combined with the unsaturated multi-arm polymer at an acidic pH that inhibits crosslinking between the unsaturated groups of the reactive multi-arm polymer and the amino groups of the iodinated polyamino compound. Then, if crosslinking is desired, the pH of the mixture of the iodinated polyamino compound and the reactive multi-arm polymer is changed from an acidic pH to a basic pH to allow crosslinking to occur between the two. In certain embodiments, the system includes (a) a first precursor composition comprising the iodinated polyamino compound described above, (b) a second precursor composition comprising the reactive multi-arm polymer described above, and (c) a third composition, specifically an accelerator composition, comprising an accelerator configured to accelerate the crosslinking reaction between the iodinated polyamino compound and the reactive multi-arm polymer.

[0037] The first precursor composition can be a first fluid composition comprising an iodinated polyamino compound buffered at an acidic pH, or a first dry composition comprising an iodinated polyamino compound and an acidic buffer composition, to which an appropriate fluid, such as water for injection or saline, can be added to form the first fluid composition comprising an iodinated polyamino compound buffered at an acidic pH. In some embodiments, for example, the acidic buffer composition can comprise monobasic sodium phosphate, among other possibilities. The first fluid composition comprising the iodinated polyamino compound can have a pH, for example, in the range of about 3 to about 5, typically in the range of about 3.5 to about 4.5, and more typically in the range of about 3.8 to about 4.2. In addition to the iodinated polyamino compound and buffer species, the first precursor composition can further comprise additional agents, such as a therapeutic agent and / or an additional imaging agent (other than the iodine groups present in the iodinated polyamino compound). The second precursor composition may be a second fluid composition comprising the reactive multi-arm polymer, or may be a second dry composition comprising the reactive multi-arm polymer from which a fluid composition is formed by the addition of an appropriate fluid, such as, for example, water for injection, saline, or a first fluid composition comprising an iodinated polyamino compound buffered at an acidic pH. In addition to the reactive multi-arm polymer, the second precursor composition may further comprise additional agents, such as a therapeutic agent and / or an additional imaging agent (other than the iodine groups present in the iodinated polyamino compound).

[0038] In a particularly advantageous embodiment, the first precursor composition is a first fluid composition including an iodinated polyamino compound buffered at an acidic pH, and the second precursor composition includes a dry composition including a reactive multi-arm polymer. The first precursor composition can then be mixed with the second precursor composition to provide a prepared fluid composition buffered at an acidic pH and including both the iodinated polyamino compound and the reactive multi-arm polymer. In a particular example, a syringe can be provided containing the first fluid composition including the iodinated polyamino compound buffered at an acidic pH, and a vial can be provided containing a dry composition (e.g., powder) including the reactive multi-arm polymer. The syringe can then be used to inject the first fluid composition into the vial containing the reactive multi-arm polymer to form a prepared fluid composition including the iodinated polyamino compound and the reactive multi-arm polymer, which can be withdrawn into the syringe for administration.

[0039] The enhancer composition may be a fluid enhancer composition buffered at a basic pH, or may be a dry composition containing a basic buffered composition, to which an appropriate fluid, such as water for injection or saline, can be added to form a fluid enhancer composition buffered at a basic pH. For example, the basic buffered composition may contain sodium borate and dibasic sodium phosphate, among other possibilities. The fluid enhancer composition may have, for example, a pH in the range of about 9 to about 11, typically about 9.5 to about 10.5, and more typically about 9.8 to about 10.2. In addition to the above, the fluid enhancer composition may further contain additional agents, such as a therapeutic agent and / or an additional imaging agent (other than the iodine group present in the iodinated polyamino compound). In certain examples, a syringe containing the fluid enhancer composition may be provided. A prepared fluid composition buffered at an acidic pH, as described above, comprising an iodinated polyamino compound and a reactive multi-arm polymer can be combined with a fluid-enhancing composition buffered at a basic pH, as described above, to form a crosslinked hydrogel either in vivo or in vitro.

[0040] Examples of additional imaging agents include: (a) fluorescent dyes such as fluorescein, indocyanine green, and fluorescent proteins (e.g., green, blue, and cyan fluorescent proteins); (b) Gd (III) , Mn (II) , Fe (III) (c) contrast agents for use with ultrasound imaging, including organic and inorganic echogenic particles (i.e., particles that result in an increase in reflected ultrasound energy) or organic and inorganic echolucent particles (i.e., particles that result in a decrease in reflected ultrasound energy); (d) contrast agents for use with magnetic resonance imaging (MRI), including contrast agents that contain elements that form paramagnetic ions such as gadolinium ion chelated with diethylenetriaminepentaacetic acid, and compounds (including chelates) containing these, such as gadolinium ion chelated with diethylenetriaminepentaacetic acid; 99m Tc-based, and 123 I, 125 I, 131 I, 111 In, 57 Co, 153 Sm, 133 Xe, 51 Cr, 81m Kr, 201 Tl, 67 Ga, 75 (e) contrast agents, such as other gamma emitters such as Se; 18 F, 11 C. 13 N, 15 O. 68(f) contrast agents for use in connection with near-infrared (NIR) imaging, which can be selected to impart near-infrared fluorescence to the coatings of the present disclosure, enabling deep tissue imaging and device marking, including NIR-sensitive nanoparticles such as gold nanoshells, carbon nanotubes (e.g., nanotubes derivatized with hydroxyl or carboxyl groups, e.g., partially oxidized carbon nanotubes), dye-containing nanoparticles such as dye-doped nanofibers and dye-encapsulated nanoparticles, and semiconductor quantum dots. NIR-sensitive dyes include cyanine dyes, squaraines, phthalocyanines, porphyrin derivatives, boron dipyrromethane (BODIPY) analogs, and the like. In various embodiments, a system is provided that includes one or more delivery devices for delivering the first and second compositions to a subject.

[0041] In some embodiments, a system may include a delivery device comprising a first reservoir containing a first composition comprising an iodinated polyamino compound, as described above, and a second reservoir containing a second composition comprising a reactive multi-arm polymer comprising a plurality of unsaturated end groups, as described above. In some embodiments, a system may include a delivery device comprising a first reservoir containing a first composition, such as the prepared fluid composition described above, comprising an iodinated polyamino compound and a reactive multi-arm polymer, buffered at an acidic pH, and a second reservoir containing a second composition, such as the fluid enhancer composition described above. In either case, during operation, the first and second compositions are dispensed from the first and second reservoirs and combined, after which the iodinated polyamino compound and the reactive multi-arm polymer crosslink to each other to form a hydrogel. In certain embodiments, the system may include a delivery device comprising a dual-barrel syringe including a first barrel having a first barrel outlet (the first barrel containing a first composition), a first plunger movable within the first barrel, a second barrel having a second barrel outlet (the second barrel containing a second composition), and a second plunger movable within the second barrel.

[0042] Regardless of the first and second compositions selected, in some embodiments, the device may further include a mixing section having a first mixing section inlet in fluid communication with the first barrel outlet, a second mixing section inlet in fluid communication with the second barrel outlet, and a mixing section outlet. In some embodiments, the device may further include a cannula or catheter tube configured to receive the first and second fluid compositions from the first and second barrels. For example, the cannula or catheter tube can be configured to form a fluid connection with the mixing section outlet by attaching the cannula or catheter tube to the mixing section outlet via a suitable fluid connector, such as a Luer connector. As another example, the catheter may be a multi-lumen catheter including a first lumen and a second lumen, a proximal end of the first lumen configured to form a fluid connection with the first barrel outlet, and a proximal end of the second lumen configured to form a fluid connection with the second barrel outlet. In some embodiments, the multi-lumen catheter may include a mixing section having a first mixing section inlet in fluid communication with the distal end of the first lumen, a second mixing section inlet in fluid communication with the distal end of the second lumen, and a mixing section outlet.

[0043] In operation, when the first and second plungers are depressed, the first and second fluid compositions are dispensed from the first and second barrels, after which the first and second fluid compositions interact and eventually crosslink to form a hydrogel, which is administered onto or into the tissue of a subject. For example, the first and second fluid compositions can enter the mixing section from the first and second barrels through the first and second mixing section inlets, after which the first and second fluid compositions mix to form a mixture, which exits the mixing section through the mixing section outlet. In some embodiments, a cannula or catheter tube can be attached to the mixing section outlet, and the mixture can be administered to a subject after passing through the cannula or catheter tube. As another example, a first fluid composition can enter a first lumen of a multi-lumen catheter through a first barrel outlet, and a second fluid composition can enter a second lumen of the multi-lumen catheter through a second barrel outlet. In some embodiments, the first and second fluid compositions can enter a mixing section at a distal end of the multi-lumen catheter from the first and second lumens through first and second mixing section inlets, respectively, and then the first and second fluid compositions mix in the mixing section to form an admixture, which exits the mixing section through a mixing section outlet.

[0044] Regardless of the type of device used to mix the first and second fluid compositions or the method by which the first and second fluid compositions are mixed, once the mixture of the first and second fluid compositions is formed, the mixture is initially in a fluid state and can be administered to a subject (e.g., a mammal, particularly a human) by a variety of techniques. Alternatively, the first and second fluid compositions can be administered separately to the subject, forming a fluid mixture of the first and second fluid compositions in or on the subject. In either approach, the fluid mixture of the first and second fluid compositions is formed and can be used in a variety of medical procedures.

[0045] For example, among other uses, the first and second fluid compositions or fluid admixtures thereof can be injected to create spacing between tissues, the first and second fluid compositions or fluid admixtures thereof can be injected to create fiducial markers (e.g., in the form of blebs), the first and second fluid compositions or fluid admixtures thereof can be injected for tissue augmentation or regeneration, the first and second fluid compositions or fluid admixtures thereof can be injected as a filler or replacement for soft tissue, the first and second fluid compositions or fluid admixtures thereof can be injected to provide mechanical support for damaged tissue, the first and second fluid compositions or fluid admixtures thereof can be injected as a scaffold, and / or the first and second fluid compositions or fluid admixtures thereof can be injected as a carrier for therapeutic agents in the treatment of disease and cancer and tissue repair and regeneration.

[0046] After administration of the compositions of the present disclosure (either separately as first and second fluid compositions that mix in vivo, or as a fluid admixture of the first and second fluid compositions), a crosslinked hydrogel is ultimately formed at the site of administration. After administration, the compositions of the present disclosure can be imaged using a suitable imaging technique, typically an X-ray-based imaging technique such as computed tomography or fluoroscopy. As can be seen from the above, the compositions of the present disclosure can be used in a variety of medical procedures, including, inter alia, the following: implanting a fiducial marker comprising the cross-linked product of the first and second fluid compositions; implanting a tissue regeneration scaffold comprising the cross-linked product of the first and second fluid compositions; implanting a tissue support comprising the cross-linked product of the first and second fluid compositions; implanting a tissue expander comprising the cross-linked product of the first and second fluid compositions; implanting a therapeutic agent-containing depot comprising the cross-linked product of the first and second fluid compositions; tissue augmentation procedures comprising implanting the cross-linked product of the first and second fluid compositions; and introducing the cross-linked product of the first and second fluid compositions between a first tissue and a second tissue to space the first tissue from the second tissue.

[0047] The first and second fluid compositions, the fluid blend of the first and second fluid compositions, or the crosslinked product of the first and second fluid compositions can be injected in conjunction with a variety of medical procedures, including injections between the prostate or vagina and the rectum for spacing purposes in radiotherapy for rectal cancer, injections between the rectum and the prostate for spacing purposes in radiotherapy for prostate cancer, subcutaneous injections for palliative treatment of prostate cancer, transurethral or submucosal injections for female stress urinary incontinence, intravesical injections for urinary incontinence, intrauterine injections for Asherman's syndrome, submucosal injections for anal incontinence, percutaneous injections for heart failure, intramyocardial injections for heart failure and dilated cardiomyopathy, transendocardial injections for myocardial infarction, intra-articular injections for osteoarthritis, spinal injections for spinal fusion and spinal, oral maxillofacial, and orthopedic trauma surgery, spinal injections for posterolateral lumbar fusion, intradiscal injections for degenerative disc disease, and injections for pancreatic adenocarcinoma. injections between the pancreas and duodenum for diagnostic imaging, resection bed injections for diagnostic imaging of oropharyngeal cancer, injections around the tumor bed for diagnostic imaging of bladder cancer, submucosal injections for gastrointestinal tumors and polyps, visceral pleural injections for lung biopsy, renal injections for type 2 diabetes and chronic kidney disease, renal cortical injections for chronic kidney disease due to congenital anomalies of the kidney or urinary tract, intravitreal injections for neovascular age-related macular degeneration, intratympanic injections for sensorineural hearing loss, correction of wrinkles, creases, folds, signs of facial fat loss, volume loss, shallow to deep contour defects, correction of depressed skin scars, perioral wrinkles, lip augmentation, facial lip atrophy, intradermal injections for stimulation of natural collagen production.

[0048] Crosslinked hydrogel compositions according to the present disclosure include lubricious compositions for medical applications, compositions for therapeutic agent release (e.g., by including one or more therapeutic agents in the matrix of the crosslinked hydrogel), and implants (which may be formed in vitro or in vivo) (e.g., compositions for use as tissue markers, compositions acting as spacers to reduce the side effects of extra-targeted radiation therapy, cosmetic compositions, etc.). [Example]

[0049] An iodinated polyamino compound, such as one of those listed above, is dissolved in an acidic buffer solution (pH 3.8-4.2) and then mixed with a reactive star PEG having unsaturated end groups, such as a star PEG having a polyol residue core region and eight hydrophilic polyethylene oxide arms with acrylate end groups, and the resulting mixture is placed in one syringe as a prepared fluid composition. Another syringe contains a fluid promoter composition in a separate buffer solution with a pH controlled at approximately 9.8-10.4. The prepared fluid composition and the fluid promoter composition are then combined to form a hydrogel, simultaneously forming a crosslinked hydrogel.

Claims

1. 1. A system for forming a hydrogel comprising: (a) an iodinated polyamino compound; and (b) a reactive multi-arm polymer comprising a plurality of hydrophilic polymer arms having unsaturated end groups reactive with the amino groups of the iodinated polyamino compound.

2. 10. The system of claim 1, wherein the iodinated polyamino compound comprises a polyamino moiety linked to a carboxy-substituted iodinated moiety by an amide group.

3. The system of claim 2 , wherein the carboxy-substituted iodinated moiety comprises an iodinated group and a carboxylic acid or carboxylate group.

4. 3. The system of claim 2, wherein the carboxy-substituted iodinated moiety is an iodinated amino acid residue and / or the carboxy-substituted iodinated moiety comprises an iodinated aromatic group and a carboxylic acid or carboxylate group.

5. The polyamino moiety is a polyamino moiety having a plurality of —(CH 2 ) x -NH 2 5. The system of claim 2, further comprising a group, wherein x is 0, 1, 2, 3, 4, 5, or 6.

6. The system of any one of claims 2 to 4, wherein the polyamino moiety comprises a residue of a carboxyl-substituted polyamino compound.

7. The system according to any one of claims 2 to 4, wherein the polyamino moiety comprises two or more amino acid residues selected from lysine, ornithine, and combinations thereof.

8. The system of any one of claims 1 to 7, wherein the unsaturated end groups are selected from acrylate ester groups and propiolate ester groups.

9. 9. The system of any one of claims 1 to 8, wherein the hydrophilic polymer arms comprise one or more hydrophilic monomers selected from ethylene oxide, N-vinylpyrrolidone, oxazoline, hydroxyethyl acrylate, hydroxyethyl methacrylate, PEG methyl ether acrylate or PEG methyl ether methacrylate, or PNIPAAM.

10. The system of any one of claims 1 to 9, wherein the unsaturated end groups are attached to the hydrophilic polymer arms by hydrolyzable ester groups.

11. The system of claim 10 , wherein the hydrolyzable ester group is selected from a glutarate group, a succinate group, a carbonate group, or an adipate group.

12. 10. The system of any one of claims 1 to 9, wherein the system comprises a first precursor composition comprising the iodinated polyamino compound, a second precursor composition comprising the reactive multi-arm polymer, and an optional accelerator composition.

13. 13. The system of claim 12, wherein the first precursor composition is provided in a syringe barrel, the second precursor composition is provided in a vial, and the accelerator composition is provided in a syringe barrel.

14. The system of any one of claims 1 to 13, further comprising a delivery device.

15. A medical hydrogel formed by crosslinking the iodinated polyamino compound and the reactive multi-arm polymer of the system of any one of claims 1 to 14 under conditions such that a medical hydrogel is formed.

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