Method for producing ac-225 solution and method for producing ac-225 labeled complex using solution

Abstract

One embodiment of the present invention is a method for producing a 225Ac solution, the method comprising a step (I) for purifying an aqueous solution (1) containing 225Ac and a carrier-derived compound (L). The carrier-derived compound (L) is a compound derived from a solid-phase carrier that carries alkyl phosphoric acid. In step (I), solid-phase extraction or liquid-liquid extraction is performed.

Description

Method for producing Ac-225 solution and method for producing Ac-225 labeled complex using the solution

[0001] One aspect of the present invention relates to a method for producing an Ac-225 solution and a method for producing an Ac-225 labeled complex using the solution.

[0002] In the field of nuclear medicine, radioisotope (RI) internal radiotherapy is performed, in which a drug containing a radioisotope (RI) is selectively taken up by lesions such as tumors for treatment. Among radiations, alpha rays have a short range and thus have the characteristic of having little influence of unnecessary exposure on surrounding normal cells. 225 Ac, which is one of the alpha-ray emitting nuclides, is a radionuclide with a half-life of 10 days and has been expected as a therapeutic nuclide in cancer treatment and the like in recent years.

[0003] 225 Ac is produced, for example, by irradiating a Ra target with particles such as protons using an accelerator 226 to cause a nuclear reaction of (p, 2n). Patent Document 1 discloses a method for separating and purifying the Ac component from a solution containing Ra ions and 226 Ac ions obtained by dissolving the Ra target after particle irradiation. 226 225 225

[0004] Japanese Patent Application Laid-Open No. 2010-502963

[0005] The present inventors have conducted research and development on complex formation between Ac ions and a chelating agent using a purified 225 Ac solution. During this process, after purification using a predetermined column, 225 a decomposition product of the column carrier elutes into the purified 225 Ac solution, and as a result, complex formation between Ac and the chelating agent is inhibited by the decomposition product, 225 and 225 a new problem has been found that the labeling rate of Ac ions to the chelating agent decreases. 225

[0006] One aspect of the present invention is to re-purify the 225 Ac solution after column purification, and 225 the labeling rate of Ac ions to the chelating agent is improved.225 This invention provides a method for producing Ac solution.

[0007] As a result of diligent research to solve the above problems, the inventors of this invention have found that the above problems can be solved by the following configuration example, and have completed the present invention.

[0008] One aspect of the present invention is, 225 The process includes a step (I) of purifying an aqueous solution (1) containing Ac and a carrier-derived compound (L), wherein the carrier-derived compound (L) is a compound derived from a solid-phase support bearing alkyl phosphate, and in step (I), solid-phase extraction or liquid-liquid extraction is performed. 225 This is a method for producing Ac solution.

[0009] Another aspect of the present invention is as described above. 225 By carrying out the method for producing the Ac solution, compared to the aqueous solution (1) 225 Ac concentration was increased. 225 In Ac solution (2) 225 The process includes a complex formation step in which Ac ions are complexed with a chelating agent. 225 This is a method for producing Ac-labeled complexes.

[0010] According to one aspect of the present invention, after column purification 225 The Ac solution was re-purified, 225 The labeling efficiency of Ac ions to chelating agents improved. 225 A method for producing Ac solution can be provided.

[0011] Figure 1 shows the chromatogram (top) and MS spectrum (bottom) of the LC-MS analysis results of the analytical sample obtained in step (1) of Test Example 1. Figure 2 shows the chromatogram (top) and MS spectrum (bottom) of the LC-MS analysis results of 2-ethylhexylphosphonate. Figure 3 shows the chromatogram (top) and MS spectrum (bottom) of the LC-MS analysis results of 2-ethylhexylphosphonate without purification treatment using a solid-phase extraction column. Figure 4 shows the chromatogram (top) and MS spectrum (bottom) of the LC-MS analysis results of 2-ethylhexylphosphonate after purification treatment using Oasis PRiME HLB Light. Figure 5 is a chromatogram showing the LC-MS analysis results when 2-ethylhexylphosphonate is purified using Sep-Pak plus light C8. Figure 6 is a chromatogram showing the LC-MS analysis results when 2-ethylhexylphosphonate is purified using Sep-Pak light C18. Figure 7 is a chromatogram showing the LC-MS analysis results when 2-ethylhexylphosphonate is purified using Sep-Pak light tC18. Figure 8 is a chromatogram showing the LC-MS analysis results when 2-ethylhexylphosphonate is purified using Oasis plus light HLB. Figure 9 is a chromatogram showing the LC-MS analysis results when 2-ethylhexylphosphonate is purified using Sep-Pak light tC2. Figure 10 is a chromatogram showing the LC-MS analysis results when 2-ethylhexylphosphonate is purified using Sep-Pak plus short PS-2.

[0012] The following describes preferred embodiments for carrying out the present invention. The embodiments described below are merely examples of typical embodiments of the present invention, and this should not be interpreted as narrowing the scope of the invention.

[0013] [ 225Method for producing Ac solution: According to one aspect of the present invention 225 The method for producing Ac solution (hereinafter also referred to as "this production method 1") is: 225 The process includes a step (I) of purifying an aqueous solution (1) containing Ac and a carrier-derived compound (L), wherein the carrier-derived compound (L) is a compound derived from a solid-phase support bearing alkyl phosphate, and in step (I), solid-phase extraction or liquid-liquid extraction is performed. 225 This is a method for producing Ac solution.

[0014] In this specification, for example, if you want to specify actinium with a mass number of 225, 225 The term "Ac" is used when there is no particular limitation on the radioactive isotope of actinium. The same applies to radium, etc.

[0015] <Process (I)> In Process (I), 225 An aqueous solution (1) containing Ac and a carrier-derived compound (L) is purified. By step (I), the carrier-derived compound (L) can be separated from the aqueous solution (1), and the carrier-derived compound (L) 225 The inhibition of complex formation between Ac ions and chelating agents is suppressed. 225 The labeling efficiency of Ac ions to chelating agents is improved.

[0016] ≪Aqueous solution (1)≫ Aqueous solution (1) is, 225 The composition is not particularly limited as long as it contains Ac and a carrier-derived compound (L), but it is preferably acidic, and more preferably has a pH of 0 or higher and 3 or lower.

[0017] Aqueous solution (1) is, 225 Ac can be obtained by purification or separation treatment using a carrier during its production. For example, it can be obtained by methods described in International Publication No. 2022 / 149578 and International Publication No. 2022 / 014555.

[0018] For example, aqueous solution (1) was obtained by the Th-229 generator or spallation method. 225 Ac was collected and eluted onto a solid support carrying alkyl phosphate. 225 It may also contain Ac. Furthermore, it may be irradiated with at least one selected from charged particles, photons, and neutrons.226 The Ra target was obtained by dissolving it in an acidic solution, etc. 226 Ra ions and 225 A Ra-Ac solution (1) containing Ac ions is passed through a solid-phase extractant (a), such as "DGA resin" or "DGA branched resin" manufactured by eichrom. 225 A step of retaining Ac ions in the solid-phase extractant (a); retained in the solid-phase extractant (a) 225 Ac ions are eluted from the solid-phase extractant (a) using an eluent (a) containing an acid (e.g., nitric acid or hydrochloric acid), and the resulting eluate (2) is passed through a solid-phase extractant (b) represented by the following formula (B), such as "Ln resin," "Ln2 resin," or "Ln3 resin" manufactured by Eichrome. 225 A step of retaining Ac ions in the solid-phase extractant (b); and retaining in the solid-phase extractant (b) 225 An aqueous solution (1) can be obtained by eluting Ac ions from the solid-phase extractant (b) using, for example, an eluent (b) containing an acid.

[0019] ≪Carrier-derived compound (L)≫ Carrier-derived compound (L) is a compound derived from a solid support that carries alkyl phosphate. In carrier-derived compound (L), "carrier-derived" means that the compound originates from the fact that, for example, when an eluent containing an acid or alkali is passed through the carrier, part or all of the carrier is altered or decomposed by chemical, physical, or both.

[0020] Alkyl phosphate is preferably a compound represented by the following formula (B).

[0021]

[0022] In formula (B), R 5 and R 6 Each of these is independently a linear or branched C8 alkyl group, or a linear or branched C8 alkoxy group, and preferred examples include an octyl group, a 2-ethylhexyl group, and a 2-methyl-4,4-dimethylpentyl group.

[0023] Preferred examples of compounds represented by formula (B) include the compounds represented by the following formulas (B-1) to (B-3).

[0024]

[0025]

[0026]

[0027] The solid support carrying alkyl phosphate is not particularly limited as long as it is a solid support containing alkyl phosphate, and may be a solid support consisting only of alkyl phosphate, or a solid support containing conventionally known components such as additives or inert supports (including solid extractants in which the compound represented by formula (B) above is introduced into the inert support).

[0028] The solid support for the alkyl phosphate may contain one compound represented by formula (B) above, or two or more compounds. The solid support for the alkyl phosphate is preferably an inert support containing the compound represented by formula (B), and more preferably a porous silica or organic polymer containing the compound represented by formula (B). The pore size of the porous silica is not particularly limited, but a diameter of about 50 μm to 150 μm is preferred.

[0029] The solid support for the alkyl phosphate is not particularly limited, but commercially available products may be used as an example, such as "Ln resin," "Ln2 resin," and "Ln3 resin" manufactured by Eichrome.

[0030] Examples of the carrier-derived compound (L) include compounds represented by the following formulas (L-1) to (L-2).

[0031]

[0032]

[0033] ≪Solid-phase extraction≫ The solid-phase extraction method can be selected by those skilled in the art without particular limitations, as long as it achieves the objectives of the present invention, but a reversed-phase solid-phase extraction is preferred. For example, by passing the aqueous solution (1) through a column containing a solid support different from the solid support bearing the alkyl phosphate (hereinafter referred to as "solid support (A)"), the support-derived compound (L) can be selectively retained, and the lapsed liquid can be purified. 225 It can be obtained as an Ac solution.

[0034] The solid phase support (A) is not limited as long as it is a reversed-phase solid phase support, and the base material may be silica gel or a polymer. When silica gel is used as the base material, an alkyl group chemically polymerized onto the silica gel surface can be used, and examples include solid phase supports in which an alkyl group or phenyl group having 1 to 30 carbon atoms is immobilized on silica gel. For example, those chemically modified with an ethylsilyl group (C2), an octylsilyl group (C8), a cyclohexylsilyl group (CH), a phenylsilyl group (PH), or an octadecylsilyl group (C18) can be used. In the case of an octadecylsilyl group (C18), it may be monofunctional or polyfunctional (difunctional or trifunctional). When a polymer is used as the base material, a styrene-divinylbenzene copolymer base material into which functional groups such as methacrylate, nitrogen-containing methacrylate, or N-vinylpyrrolidone have been introduced, or a polymer using polyamide chemistry, or the styrene-divinylbenzene copolymer itself can be used. The solid phase support (A) is preferably a polymer combining divinylbenzene (hydrophobic group) and N-vinylpyrrolidone (hydrophilic group) (divinylbenzene-N-vinylpyrrolidone copolymer), and more preferably a solid phase support comprising a porous polymer made of a copolymer of divinylbenzene and N-vinylpyrrolidone.The column containing the solid phase support (A) may be a commercially available product, for example, HLB-Prime (Waters), Sep-Pak tC18 (Waters), Sep-Pak C18 (Waters), Sep-Pak C8 (Waters), Strata C18 (Phenomenex), Sep-Pak light tC2 (Waters), Sep-Pak plus short PS-2, and SampliQ OPT (Agilent), as well as the series of products in which these products and the support are the same: Oasis PRiME HLB Light (Waters), Sep-Pak plus light C8 (Waters), Sep-Pak Examples include light C18 (manufactured by Waters), Sep-Pak light tC18 (manufactured by Waters), Oasis plus light HLB (manufactured by Waters), and Sep-Pak Light C18 Cartridges (manufactured by Waters). When performing solid-phase extraction, a column containing one or more solid-phase supports (A) may be used, and one or more such columns may be used.

[0035] When passing the aqueous solution (1) through the solid support (A), the eluate from the solid support carrying the alkyl phosphate may be passed through the solid support (A) as is, or it may be diluted or its pH adjusted. However, it is preferable to pass the eluate from the solid support (b) carrying the alkyl phosphate directly through the solid support (A). The flow rate of the aqueous solution (1) when passing it through the solid support (A) is not particularly limited as long as the support-derived compound (L) can be efficiently separated from the aqueous solution (1), but for example, it is 1 L / min or less, and preferably 10 mL / min or less.

[0036] The above solid-phase extraction may be performed only once, or it may be performed multiple times by passing the permeate through a column containing the solid phase support (A). The above solid-phase extraction may further include a step of washing the solid phase support (A) after passing the aqueous solution (1) through it.

[0037] <Liquid-Liquid Extraction> The liquid-liquid extraction method can be performed using any method that can be selected by those skilled in the art, without particular limitations, as long as the objectives of the present invention are achieved. The aqueous solution (1) is liquid-liquid extracted using an organic solvent. 225 The mixture is separated into a water-soluble fraction containing Ac (aqueous layer) and an organic solvent fraction in which the above-mentioned carrier-derived compound (L) is dissolved (organic solvent layer). 225 The water-soluble fraction containing Ac was recovered and purified. 225 It can be obtained as an Ac solution.

[0038] The organic solvent used for liquid-liquid extraction is not particularly limited as long as it is a solvent that is poorly miscible with water. However, from the viewpoint of the solubility of the carrier-derived compound (L), it is preferable to use one or more organic solvents selected from the group consisting of ethyl acetate, hexane, diethyl ether, petroleum ether, dichloromethane, chloroform, tetrahydrofuran, acetone, methyl ethyl ketone, butanol, octanol, and acetonitrile. It is more preferable to use ethyl acetate, diethyl ether, methyl ethyl ketone, butanol, and octanol, and even more preferable to use ethyl acetate.

[0039] When performing liquid-liquid extraction, the amount of organic solvent used is not particularly limited, but it is preferably 37% by mass or more relative to the aqueous solution (1), more preferably 37 to 57% by mass, and even more preferably 42 to 52% by mass.

[0040] [ 225 Method for producing Ac-labeled complexes: According to one aspect of the present invention 225 The method for producing the Ac-labeled complex (hereinafter also referred to as "this production method 2") is as described above. 225 By carrying out the method for producing Ac solution, compared to the aqueous solution (1) above, 225 Ac concentration was increased. 225 In Ac solution (2) 225 The process includes a complex formation step in which Ac ions are complexed with a chelating agent.

[0041] <Complex formation process> 225 Ac solution (2) was obtained in the above manufacturing method 1. 225Since this is an Ac solution, and the above-mentioned carrier-derived compound (L) can be separated and removed from the aqueous solution (1) by this manufacturing method 1, compared to the above-mentioned aqueous solution (1) 225 This results in a solution with a higher concentration (especially purity) of Ac.

[0042] The reaction conditions in the complex formation step can be, for example, the following conditions. The solvent used in this step can be, for example, water, physiological saline, or buffers such as sodium acetate buffer, ammonium acetate buffer, phosphate buffer, phosphate-buffered physiological saline, Tris buffer, HEPES buffer, or tetramethylammonium acetate buffer, or water-soluble organic solvents such as alcohols with 1 to 5 carbon atoms, acetonitrile, N,N-dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, and acetone, or mixed solvents thereof.

[0043] The reaction temperature may be, for example, room temperature (25°C) or under heating conditions. However, from the viewpoint of suppressing the decomposition of the chelating agent and improving the efficiency of complex formation, the upper limit is preferably 90°C or lower, more preferably 80°C or lower, and even more preferably 75°C or lower. The lower limit is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher. Preferably, the temperature is heated to 60°C or higher and 80°C or lower, more preferably 65°C or higher and 75°C or lower.

[0044] The reaction time, provided the reaction temperature is as described above, has a lower limit of 3 minutes or more, preferably 5 minutes or more, more preferably 10 minutes or more, and even more preferably 13 minutes or more, and an upper limit of 1 hour or less, preferably 30 minutes or less, more preferably 20 minutes or less, and even more preferably 18 minutes or less. The reaction time is usually 3 minutes or more and 1 hour or less, preferably 10 minutes or more and 20 minutes or less, and more preferably 13 minutes or more and 18 minutes or less.

[0045] Chelating agents and 225 The molar ratio of Ac ions also varies depending on the type of chelating agent used, but the chelating agent / 225The Ac ion is preferably 100 or more, more preferably 200 or more, even more preferably 400 or more, preferably 16000 or less, more preferably 8000 or less, and even more preferably 4000 or less.

[0046] The pH of the reaction solution can be appropriately changed depending on the physical properties of the chelating agent and buffering agent, but the lower limit is preferably 3.0, more preferably 4.0, and still preferably 4.5, and the upper limit is preferably 7.0, more preferably 6.0, and still preferably 5.5. The pH is preferably 4.0 to 6.0, and more preferably 4.5 to 5.5.

[0047] <Chelating Agents> The above chelating agents are, 225The substance is not particularly limited as long as it can form a complex with Ac ions, but examples include the following compounds and substances containing structures derived from said compounds.・DOTA (1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid)・DOTMA ((1R, 4R, 7R, 10R)-α, α', α'', α'''-tetramethyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid)・DOTAM (1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane) ・DOTA-GA (α-(2-Carboxyethyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid)・DOTP (((1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetrayl)tetrakis(methylene))tetraphosphonic acid)・DOTMP (1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetrakis (methylenephosphonic acid)) ・DOTA-4AMP (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis (acetamide methylenephosphonic acid)・DO2P (Tetraazacyclododecane dimethanephosphonic acid)・H2macropa (6-(1,4,10,13-tetraoxa-7,16-diazacyclooctadecan-N,N'-methyl)picolinic acid)

[0048] These chelating agents may be compounded with targeting agents such as linear or cyclic peptides, nucleic acids, antibody fragments, antibodies, glycans, lipids, small molecular weight pharmaceutical molecules, polymers, or nanoparticle carriers. A targeting agent refers to an agent having a chemical structure that exhibits directivity to a target organ or tissue in the body, or specificity to a target molecule, and is preferably a polypeptide. A polypeptide may be any peptide having three or more amino acid residues, but specifically, it may be a linear peptide, a cyclic peptide or a combination thereof, a protein, an antibody or its fragment, for example, an antibody (immunoglobulin) having the classes IgG, IgA, IgM, IgD, IgE, Fab fragment, F(ab') ２ Examples include antibody fragments such as fragments and peptide aptamers. The complexation of the chelating agent and the targeting agent may be formed by covalent bonds such as amide bonds, thioether bonds, or triazole bonds formed by click reactions, or by non-covalent bonds such as electrostatic or hydrophobic interactions. For example, chelating agents can be used that are linked to structures that have affinity for proteins expressed in cancer tissue, such as CA-IX, PSMA, GLP-1 receptor, somatostatin receptor, and integrin.

[0049] Furthermore, these chelating agents may have a reactive atomic group that can bind to a targeting agent introduced into their structure, for example, they may contain a click reaction-capable atomic group. A click reaction is a reaction that occurs, for example, with a combination of an alkyne and an azide, or a combination of a diene and a dienophile, where the azide group (-N ３ Chelating agents containing an alkynyl group (-C≡C-), an alkenyl group (-C=C-), or a dienophile group in their structure may be used. The click-reactive atomic group is preferably one that can be used in a metal catalyst-free click reaction. Specific examples of click reactions using such combinations of atomic groups include the Husgen cycloaddition reaction and the reverse electron-demanded Diels-Alder reaction.

[0050] Specific examples of click-reaction-capable atomic groups include atomic groups containing dibenzocyclooctyne (DBCO) as an alkyne, atomic groups containing an azide group as an azide, atomic groups containing 1,2,4,5-tetrazine as a diene, and atomic groups containing trans-cyclooctene (TCO) as an alkene (dienophile). When introducing click-reaction-capable atomic groups, various commercially available reagents can be used. Specifically, when introducing an atomic group containing dibenzocyclooctyne (DBCO) as a click-reaction-capable atomic group, for example, DBCO-C6-Acid, DBCO-Amine, DBCO-Maleimide, DBCO-PEG acid, DBCOPEG-NHS DBCO reagents such as ester, DBCO-PEG-Alcohol, DBCO-PEG-amine, DBCO-PEG-NH-Boc, Carboxyrhodamine-PEG-DBCO, Sulforhodamine-PEG-DBCO, TAMRA-PEG-DBCO, DBCO-PEG-Biotin, DBCO-PEGDBCO, DBCO-PEG-Maleimide, TCO-PEG-DBCO, and DBCO-mPEG can be used.

[0051] The complex formation process described above 225 The Ac-labeled complex may be used as is, but it may also be purified using a filtration filter, membrane filter, or the like to remove impurities such as unreacted material from the process.

[0052] [Other aspects of the present invention] Other aspects of the present invention relate to the following [1] to

[15] : 225 Method for producing Ac solution and 225 A method for producing Ac-labeled complexes can also be mentioned.

[0053] [1] 225 The process includes a step (I) of purifying an aqueous solution (1) containing Ac and a carrier-derived compound (L), wherein the carrier-derived compound (L) is a compound derived from a solid support carrying alkyl phosphate, and in step (I), solid-phase extraction or liquid-liquid extraction is performed. 225 A method for producing Ac solution. [2] The method described in [1] wherein the aqueous solution (1) is acidic. 225A method for producing Ac solution. [3] The method according to [1] or [2], wherein the alkyl phosphoric acid is a compound represented by the following formula (B). 225 A method for producing Ac solution. [In formula (B), R 5 and R 6 Each of these is independently an alkyl group having 8 carbon atoms or an alkoxy group having 8 carbon atoms. [4] The solid-phase extraction is a reversed-phase solid-phase extraction as described in any of [1] to [3]. 225 A method for producing Ac solution. [5] The method for producing Ac solution, wherein in the solid phase extraction described above, the aqueous solution (1) is passed through a solid phase support comprising a porous polymer made of a copolymer of divinylbenzene and N-vinylpyrrolidone, as described in [4]. 225 A method for producing Ac solution. [6] The liquid-liquid extraction is carried out by dissolving the carrier-derived compound (L) in one or more organic solvents selected from the group consisting of ethyl acetate, hexane, diethyl ether, petroleum ether, dichloromethane, chloroform, tetrahydrofuran, acetone, methyl ethyl ketone, butanol, octanol, and acetonitrile, according to any one of [1] to [3]. [7] The above method ２２５ Ac and ２２６ From Ra-Ac solution (1) containing Ra 225 The process includes a step to purify Ac, and uses a solid-phase extractant (b) supporting alkyl phosphate. ２２５ The method described in any one of [1] to [6] includes separating Ac to obtain an aqueous solution (1). 225 Method for producing Ac solution. [8] From the above Ra-Ac solution (1) 225 The step of purifying Ac involves using a solid-phase extractant (b) supporting the alkyl phosphate. 225 A step to collect Ac, and a step to extract from the solid-phase extractant (b) supporting the alkyl phosphate with acid 225 The method described in [7] comprises the step of eluting Ac to obtain the aqueous solution (1), wherein the acid is preferably nitric acid, and when the acid is nitric acid, the concentration of nitric acid is preferably 0.01 M or more, more preferably 0.1 M or more, preferably 10 M or less, more preferably 0.9 M or less. 225Method for producing an Ac solution. [9] including passing the aqueous solution (1) eluted from the solid-phase extraction agent (b) carrying the alkyl phosphoric acid directly through the solid-phase carrier (A), as described in [7] or [8] 225 Method for producing an Ac solution.

[10] The Ra-Ac solution (1) is 226 a solution obtained by irradiating a Ra target with at least one selected from charged particles, photons, and neutrons (preferably, protons or photons) and then 226 dissolving the Ra target, as described in any one of [7] to [9] 225 Method for producing an Ac solution.

[11] As described in any one of [1] to

[10] 225 By performing the method for producing an Ac solution, compared to the above aqueous solution (1) 225 an Ac solution (2) with an increased Ac concentration 225 in which the Ac ions in 225 are complexed with a chelating agent, including a complex formation step 225 Method for producing an Ac-labeled complex.

[12] The chelating agent is a substance containing a structure derived from DOTA, DOTMA, DOTAM, DOTA-GA, DOTP, DOTMP, DOTA-4AMP, DO2P, or H2macropar or these compounds, as described in

[11] 225 Method for producing an Ac-labeled complex.

[13] A structure having an affinity for a protein expressed in cancer tissue is linked to the chelating agent, as described in

[11] or

[12] 225 Method for producing an Ac-labeled complex.

[14] An atom group capable of a click reaction is introduced into the chelating agent, as described in

[11] to

[13] 225 Method for producing an Ac-labeled complex.

[15] As the atom group capable of a click reaction introduced into the chelating agent, dibenzocyclooctyne (DBCO), an azide group, 1,2,4,5-tetrazine, and trans-cyclooctene (TCO) are introduced, as described in

[14] 225 Method for producing an Ac-labeled complex.

[0054] Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited to these examples and can be implemented by appropriately changing within the scope not changing the gist.

[0055] [Test Example 1] [ 225 [Analysis of Ac purification column eluents] (1) Preparation of DGA-LN resin carrier-derived compounds In [Test Example 1] of International Publication No. 2022 / 014555, instead of solution (1-1), a 0.7 mol / L nitric acid solution ( 225 The same procedure was performed except for the use of Ac) and the solution was collected by passing it through DGA resin (manufactured by Eichrome Technologies) and Ln resin (manufactured by Eichrome Technologies) (see

[0069] of International Publication No. 2022 / 014555). 225 The solution equivalent to the Ac solution was removed by distillation under heating conditions of 110°C. After the solution dried, ultrapure water was added and the solution was removed again by distillation. After confirming that it had dried, the solution was heated for an additional 2 hours to completely remove the acid. The residue in the vial was redissolved in 100 μL of 10% acetonitrile aqueous solution and used as the LC-MS analysis sample.

[0056] (2) Analysis of carrier-derived compounds by LC-MS 10 μL of the analytical sample solution obtained in step (1) above was analyzed using a mass spectrometer (Q Extraxive Plus, Thermo Fisher Scientific) connected to an AQUITY UPLC CSH C18 column (1.7 μm, 2.1 × 100 mm, Waters). The obtained chromatogram and MS spectrum are shown in Figure 1.

[0057] The LC-MS measurement conditions are as follows: Flow rate: 0.2 mL / min; Mobile phase A: 0.1% formic acid aqueous solution; Mobile phase B: 0.1% formic acid-containing acetonitrile solution; Time: 0-5 min: 10% B, 5-8 min: 10-40% B, 8-30 min: 40-100% B, 30-40 min: 100% B, 40-40.1 min: 100-10% B, 40.1-45 min: 10% B

[0058] LC-MS analysis was similarly performed on 2-ethylhexylphosphonate (Mono- and Di-Ester mixture, manufactured by Tokyo Chemical Industry Co., Ltd.), represented by the above formula (L-1), as a standard. 2-ethylhexylphosphonate was prepared as a 10 μmol / L ethanol solution, and 10 μL was analyzed by LC-MS. The chromatogram and MS spectrum of the obtained standard are shown in Figure 2.

[0059] From the results in Figures 1 and 2, 225 The eluate from the Ac purification column showed that it contained 2-ethylhexylphosphonate as a compound derived from the carrier used.

[0060] [Example 1] [ 225 [Verification of the effect of Ac purification on labeling] (1) 225 The procedure is the same as in [Example 1] of the International Publication No. 2022 / 149578 for the production of Ac radionuclides and purification using DGA-LN resin. 225 Ac solution was obtained.

[0061] (2) 225 Purification of Ac solution by ethyl acetate extraction obtained in step (1) above 225 4.4 mL of Ac solution (equivalent to 165.5 MBq at the end of cyclotron irradiation) was added to a syringe fitted with a three-way stopcock and with the plunger withdrawn, along with 1.0 mL of the washings from the vial. 5.4 mL of ethyl acetate solution was then added and the mixture was stirred for 3 minutes using a Pasteur pipette. After removing the organic phase, the process of adding ethyl acetate, stirring by pipetting, and removing the organic phase was repeated a total of three times. The aqueous phase was collected and measured at 142.3 MBq at the end of cyclotron irradiation. 225 Ac solution was obtained (recovery rate 86.0%).

[0062] (3) 225 A purified solid-phase extraction column (HLB-Prime, Waters) of Ac solution was conditioned by passing 10 mL of ethanol, 10 mL of sterile water for injection, 10 mL of 0.7 mol / L nitric acid aqueous solution, and 10 mL of sterile water for injection through it in that order. The result obtained in step (1) above 2252.2 mL of Ac solution was passed through a solid-phase extraction column, and the liquid that passed through was collected and this solution was prepared. 225 The Ac solution was used in subsequent experiments (64.8 MBq at the end of cyclotron irradiation, with a recovery rate of 87.7%).

[0063] (4) To chelating agents 225 The structure of the chelating agent (DOTAGA-DBCO) used in this Ac-labeled example is shown in the following formula (L1-5). 225 Ac solution (Entry 1), or obtained in step (1) 225 Three types of Ac solutions were prepared by distillation under heating conditions: one purified in step (2) (Entry 2), and the other purified in step (3) (Entry 3). After the solution dried, ultrapure water was added and the solution was distilled again. After confirming that the solution was dry, the solution was heated for an additional 2 hours to remove the nitric acid. The chelating agent was dispersed in 100 mmol / L acetic acid-sodium acetate buffer (pH 5.0) to obtain a dispersion containing 0.3 mmol / L of the chelating agent (chelating agent dispersion). 0.09 mL of this dispersion and 0.135 mL of 75 mmol / L gentisic acid solution (dissolved in 100 mmol / L acetic acid-sodium acetate buffer (pH 5.0) and adjusted to pH 5.0) were subjected to solvent removal. 225 In addition to Ac, react under heating conditions, 225 An Ac complex solution was obtained. A chelating agent and 225 The molar ratio with Ac ions is as follows: 225 The Ac ion ratio was approximately 1361.1:1, and the reaction solution was heated to 70°C for 15 minutes.

[0064] obtained 225 The radiochemical purity of the Ac complex was measured using thin-layer chromatography (Agilent, model number: SGI0001, developing solvent: acetonitrile:water (volume ratio 1:1)) with a radio-γ-TLC analyzer (raytest, MODELGITA Star PS). The radiochemical purity (labeling efficiency) (%) was defined as the percentage of the radioactivity (count) of the peak detected near the solvent tip relative to the total detected radioactivity (count). The labeling efficiency is shown in Table 1.

[0065]

[0066]

[0067] [Example 2] [Labeling under compound (L) addition conditions] (1) Obtained by the method of steps (1) and (2) of Example 1 225 To the Ac solution, 13.5 nmol (Entry 1), 135 nmol (Entry 2), 1.35 μmol (Entry 3), and 13.5 μmol (Entry 4) of 2-Ethylhexyl Phosphate (Mono- and Di-Ester mixture, EHP, manufactured by Tokyo Chemical Industry Co., Ltd.), dissolved in ethanol, were added and removed by distillation under heating conditions. The chelating agent was dispersed in 100 mmol / L acetic acid-sodium acetate buffer (pH 5.0) to obtain a dispersion containing 0.3 mmol / L of the chelating agent (chelating agent dispersion). 45 μL of this dispersion and 67.5 μL of 75 mmol / L gentisic acid solution (dissolved in 100 mmol / L acetic acid-sodium acetate buffer (pH 5.0) and pH adjusted to 5.0) were removed by distillation. 225 In addition to Ac, react under heating conditions, 225 An Ac complex solution was obtained. A chelating agent and 225 The molar ratio with Ac ions is as follows: 225 The Ac ion ratio was approximately 3500.7:1, the reaction solution was heated to 70°C for 15 minutes, and the labeling fractions obtained in the same manner as in step (4) of Example 1 are shown in Table 2.

[0068]

[0069] [Test Example 2] [Verification of the effect of removing carrier-derived compounds by solid-phase extraction column] (1) Preparation of a carrier-derived compound-containing solution 2-ethylhexylphosphonate (Mono- and Di-Ester mixture, manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the above formula (L-1) was used as the standard. The 2-ethylhexylphosphonate was dissolved in nitric acid to prepare a 0.7 mol / L nitric acid solution (final concentration of EHP 500 μmol / L), which was used as the carrier-derived compound-containing solution.

[0070] (2) Purification by solid-phase extraction column A solid-phase extraction column (Oasis PRiME HLB-Light, manufactured by Waters) was conditioned by passing 10 mL of ethanol, 10 mL of sterile water for injection, 10 mL of 0.7 mol / L aqueous nitric acid solution, and 10 mL of sterile water for injection in that order. The carrier-derived compound-containing solution obtained in step (1) above was passed through the solid-phase extraction column, and the liquid that passed through was collected as the analytical sample. In addition, as a comparative sample, the same solution was subjected to direct analysis without passing it through the solid-phase extraction column.

[0071] (3) Analysis of carrier-derived compounds by LC-MS 50 μL of the analytical sample solution obtained in step (2) above was analyzed using a mass spectrometer (Q Extractive Plus, Thermo Fisher Scientific) connected to an AQUITY UPLC CSH C18 column (1.7 μm, 2.1 × 100 mm, Waters). The obtained chromatograms and MS spectra are shown in Figure 3 for the comparative sample that was not passed through the solid-phase extraction column, and in Figure 4 for the analytical sample that was passed through the solid-phase extraction column.

[0072] The LC-MS measurement conditions are as follows: Flow rate: 0.2 mL / min; Mobile phase A: 0.1% formic acid aqueous solution; Mobile phase B: methanol solution; Time: 0-5 min: 10% B, 5-8 min: 10-40% B, 8-35 min: 40-100% B, 35-45 min: 100% B, 45-45.1 min: 100-10% B

[0073] In the chromatogram and MS spectrum of Figure 3, the peak of 2-ethylhexylphosphonate, enclosed in a square, was not detected in Figure 4. This suggests that 2-ethylhexylphosphonate was removed by the solid-phase extraction column used.

[0074] [Test Example 3] In the same manner as in Test Example 2, except that Sep-Pak plus light C8, Sep-Pak light C18, Sep-Pak light tC18, Oasis plus light HLB, Sep-Pak light tC2, or Sep-Pak plus short PS-2 (all manufactured by Waters) were used instead of Oasis PRiME HLB-Light, the carrier-derived compound-containing solution was passed through each solid-phase extraction column, and the obtained analytical samples were subjected to LC-MS analysis. The results are shown in Figures 5 to 10.

[0075] Similar to the solid-phase extraction column used in Test Example 2, the 2-ethylhexylphosphonate peak in the chromatogram in Figure 3 was not detected in Figures 5-10, suggesting that 2-ethylhexylphosphonate was removed by each solid-phase extraction column used in Test Example 3.

[0076] [Example 3] [by solid-phase extraction column] 225 Verification of the effects of Ac purification 1] (1) 225 The procedure is the same as in [Example 1] of the International Publication No. 2022 / 149578 for the production of Ac radionuclides and purification using DGA-LN resin. 225 Ac solution was obtained.

[0077] (2) 225 As the solid-phase extraction column for purification by solid-phase extraction (SPE) of Ac solution, Oasis PRiME HLB-Light, Sep-Pak plus short PS-2, or Sep-Pak light C18 Cartridges (manufactured by Waters) were used, and each solid-phase extraction column was conditioned by passing 10 mL of ethanol, 10 mL of sterile water for injection, 10 mL of 0.7 mol / L nitric acid aqueous solution, and 10 mL of sterile water for injection in that order. The result obtained in step (1) above 225 2.2 mL of Ac solution was passed through each solid-phase extraction column, and the liquid that passed through was collected and this solution was prepared. 225The Ac solution was used in subsequent experiments. The radioactivity of each column before purification (purified radioactivity) and the radioactivity after recovery of the liquid passed through (recovered radioactivity) were measured using a radioisotope dose calibrator (CAPINTEC, CRC-15R). The ratio of recovered radioactivity to purified radioactivity (purification recovery rate (%)) is shown in Table 3.

[0078] (3) To chelating agents 225 Ac labeling Each obtained in step (2) above 225 The solvent was removed from the Ac solution by heating at 110°C for 2 hours. 225 Ac was redissolved by adding a 75 mmol / L gentisic acid solution (dissolved in 100 mmol / L acetic acid-sodium acetate buffer (pH 5.0) and adjusting the pH to 5.0). In a 1.5 mL tube, 225 25 μL of a 75 mmol / L gentisic acid solution containing 0.79–1.13 MBq of Ac was mixed with a dispersion of a chelating agent (a dispersion containing 0.3 mmol / L of a chelating agent prepared by dispersing DOTAGA-DBCO in 100 mmol / L acetic acid-sodium acetate buffer (pH 5.0)). The resulting mixture was heated at 70°C for 15 minutes to allow it to react. 225 An Ac complex solution was obtained. A chelating agent and 225 The molar ratio with Ac ions is as follows: 225 The ratio of Ac ions was between 4318.3 and 6176.8.

[0079] obtained 225 The radiochemical purity of the Ac complex was measured using thin-layer chromatography (Agilent, model number: SGI0001, developing solvent: acetonitrile:water (volume ratio 1:1)) with a radio-γ-TLC analyzer (raytest, MODELGITA Star PS). The radiochemical purity (labeling efficiency) (%) was defined as the percentage of the radioactivity (count) of the peak detected near the solvent tip relative to the total detected radioactivity (count). The labeling efficiency is shown in Table 3.

[0080]

[0081] [Example 4] [by solid-phase extraction column] 225 Verification of the effects of Ac purification (2) (1) 225The procedure is the same as in [Example 1] of the International Publication No. 2022 / 149578 for the production of Ac radionuclides and purification using DGA-LN resin. 225 Ac solution was obtained.

[0082] (2) 225 As a solid-phase extraction column for purification by solid-phase extraction (SPE) of Ac solution, an Oasis PRiME HLB-Light (manufactured by Waters) was used, and the solid-phase extraction column was conditioned by passing 10 mL of ethanol, 10 mL of sterile water for injection, 10 mL of 0.7 mol / L nitric acid aqueous solution, and 10 mL of sterile water for injection in that order through the column. The result obtained in step (1) above 225 Ac solution (3.25 MBq) was passed through a solid-phase extraction column, and the solvent was removed by distillation under heating conditions of 110°C for 2 hours. After distillation, 1.2 mL of 0.1 mol / L hydrochloric acid was added to redissolve the solution.

[0083] (3) Preparation of a solution containing a carrier-derived compound 2-ethylhexylphosphonate (Mono- and Di-Ester mixture, manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in ethanol to prepare a 60 mmol / L EHP ethanol solution.

[0084] (4) To chelating agents 225 The redissolved solution obtained in step (2) above (labeled with Ac) was dispensed into four vials, each containing 300 μL. 67.5 μL of the EHP ethanol solution prepared in step (3) above was added to two of these vials. The solutions in each vial were heated at 110°C for 40 minutes to remove the solvent.

[0085] To each vial, 45 μL of 0.1 mol / L acetate buffer (pH 5.0) containing each chelating agent (0.3 mmol / L) shown in Table 4 below, and 67.5 μL of 0.1 mol / L acetate buffer (pH 5.0) were added. After reacting at 70°C for 1 hour, the labeling efficiency (%) was calculated in the same manner as in Example 1. The results are shown in Table 5. PSMA617 was a product of Astatech Inc., and DOTA-TATE was a product of Bachem AG.

[0086]

[0087] This application is based on Japanese Patent Application No. 2024-163827 (filing date: September 20, 2024), the contents of which are fully incorporated herein.

Claims

1. 225 The process includes a step (I) of purifying an aqueous solution (1) containing Ac and a carrier-derived compound (L), wherein the carrier-derived compound (L) is a compound derived from a solid-phase support bearing alkyl phosphate, and in step (I), solid-phase extraction or liquid-liquid extraction is performed. 225 A method for producing Ac solution.

2. The aqueous solution (1) is acidic, as described in claim 1. 225 A method for producing Ac solution.

3. The claim according to claim 1 or 2, wherein the alkyl phosphate is a compound represented by the following formula (B). 225 A method for producing Ac solution. [In formula (B), R 5 and R 6 Each of these is independently an alkyl group having 8 carbon atoms or an alkoxy group having 8 carbon atoms.

4. The solid-phase extraction is a reversed-phase solid-phase extraction according to claim 1 or 2. 225 A method for producing Ac solution.

5. The solid phase extraction method according to claim 4, wherein the aqueous solution (1) is passed through a solid phase support comprising a polymer composed of a copolymer of divinylbenzene and N-vinylpyrrolidone. 225 A method for producing Ac solution.

6. The liquid-liquid extraction is carried out by dissolving the carrier-derived compound (L) in an organic solvent selected from the group consisting of ethyl acetate, hexane, diethyl ether, petroleum ether, dichloromethane, chloroform, tetrahydrofuran, acetone, methyl ethyl ketone, butanol, octanol, and acetonitrile. The method for producing an 225 Ac solution according to claim 1.

7. The invention described in claim 1 or 2 225 By carrying out the method for producing the Ac solution, compared to the aqueous solution (1) 225 Ac concentration was increased. 225 In Ac solution (2) 225 The process includes a complex formation step in which Ac ions are complexed with a chelating agent. 225 A method for producing Ac-labeled complexes.

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