Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
  • C07B59/00—Introduction of isotopes of elements into organic compounds ; Labelled organic compounds per se
  • C07B59/004—Acyclic, carbocyclic or heterocyclic compounds containing elements other than carbon, hydrogen, halogen, oxygen, nitrogen, sulfur, selenium or tellurium
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
  • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D257/00—Heterocyclic compounds containing rings having four nitrogen atoms as the only ring hetero atoms
  • C07D257/02—Heterocyclic compounds containing rings having four nitrogen atoms as the only ring hetero atoms not condensed with other rings
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D403/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00
  • C07D403/02—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00 containing two hetero rings
  • C07D403/12—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00 containing two hetero rings linked by a chain containing hetero atoms as chain links
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
  • C07B2200/00—Indexing scheme relating to specific properties of organic compounds
  • C07B2200/05—Isotopically modified compounds, e.g. labelled

Definitions

• the present invention relates to a method for producing a radioactive metal complex.
• Radioactive metal complex formation reaction To efficiently synthesize radioactive metal complexes in which a ligand compound is coordinated to a radioactive metal nuclide for use in reagents and diagnostic agents for detecting target molecules, or pharmaceuticals for treating diseases. is currently being considered.
• One such study includes irradiation with microwaves when performing a reaction in which a ligand compound is coordinated with a radioactive metal nuclide (hereinafter also referred to as a "radioactive metal complex formation reaction").
• Patent Document 1 describes a method for producing a radioactive metal complex labeled with 225 Ac. This document states that when heating is required when performing a radioactive metal complex formation reaction between a ligand compound and 225 Ac, heating is preferably performed by microwave irradiation.
• Non-Patent Document 1 describes a method for producing a radioactive metal complex consisting of 68 Ga and DOTATOC, which is a ligand compound. The same document states that by irradiating microwaves and heating to 90°C during the radioactive metal complex formation reaction, the desired 68 Ga complex can be obtained in a shorter time than when heating with a block heater. is listed.
• Non-Patent Document 2 describes a method for producing a radioactive metal complex consisting of 89 Zr and TRITA, which is a ligand compound. This document states that by irradiating microwaves and heating to 180°C during the radioactive metal complex formation reaction, the desired 89 Zr can be produced in a shorter time and in higher yields than when using normal heating methods. It is stated that complexes are obtained.
• Patent Document 1 In Patent Document 1, Non-Patent Document 1, and Non-Patent Document 2, detailed conditions for microwave irradiation in the radioactive metal complex formation reaction are not examined. Due to this, the reaction acceleration effect of microwave irradiation was not maximized, and there remained room for improvement in the reaction efficiency of the radioactive metal complex formation reaction.
• an object of the present invention is to allow the radioactive metal complex formation reaction to proceed more efficiently.
• the present invention provides a radioactive metal nuclide; A complex forming step of reacting a ligand compound represented by the following formula (1) in a reaction solution containing water and a buffer to form a radioactive metal complex,
• the buffer agent contains one or more water-soluble organic compounds having a sulfo group or a carboxy group,
• the present invention provides a method for producing a radioactive metal complex, in which the reaction solution is irradiated with microwaves while cooling the reaction solution in the complex formation step.
• R 11 , R 12 and R 13 are each independently -(CH 2 ) p COOH, -(CH 2 ) p C 5 H 4 N, -(CH 2 ) p PO 3 A group consisting of H 2 or -(CH 2 ) p CONH 2 , where one of R 14 or R 15 is a hydrogen atom, -(CH 2 ) p COOH, -(CH 2 ) p C 5 H 4 N, -(CH 2 ) p PO 3 H 2 , -(CH 2 ) p CONH 2 , or -(CHCOOH)(CH 2 ) p COOH, and the other is -(CH 2 )pCOOH, -( A group consisting of CH 2 ) p C 5 H 4 N, -(CH 2 ) p PO 3 H 2 , or -(CH 2 ) p CONH 2 , or a reactive atomic group or a group for linking with a targeting agent. It is a group
• a method for producing a radioactive metal complex which allows the radioactive metal complex formation reaction to proceed more efficiently.
• the production method of the present invention includes a complex forming step in which a radioactive metal nuclide and a ligand compound represented by formula (1) described below are reacted in a reaction solution to form a radioactive metal complex.
• This radioactive metal complex is a compound in which a radioactive metal atom is bonded to a ligand compound through a combination of covalent bonds, ionic bonds, etc. in addition to coordinate bonds, and a reactive atomic group or targeting agent, which will be described later, is further bonded.
• Compounds that are also included are included.
• complexing a radioactive metal ion and a ligand compound and labeling a ligand compound with a radioactive metal ion are synonymous, and complex formation efficiency and labeling rate are synonymous.
• the radioactive metal nuclide used in the complex formation step is preferably used in the form of a compound that can be ionized in water, and more preferably in the form of a metal ion (hereinafter, these forms are collectively referred to as (Also referred to as a ⁇ radioactive metal source.'')
• a radioactive metal ion-containing liquid in which radioactive metal ions are dissolved or dispersed in a water-based solvent can be used.
• the radioactive metal nuclide contained in the radioactive complex of the present invention is a radionuclide that emits ⁇ rays, a radionuclide that emits ⁇ rays, a radionuclide that emits positrons, or a radionuclide that emits ⁇ rays.
• a radionuclide that emits ⁇ rays or a radionuclide that emits ⁇ rays it is preferable to use a radionuclide that emits ⁇ rays or a radionuclide that emits ⁇ rays.
• radionuclide that emits positrons or a radionuclide that emits gamma rays.
• radionuclides that emit alpha rays include 212 Bi, 213 Bi, 225 Ac, and 227 Th.
• 64 Cu, 90 Y, or 177 Lu is exemplified as a radionuclide that emits ⁇ rays.
• examples of radionuclides that emit positrons include 64 Cu, 68 Ga, 86 Y, and 89 Zr.
• 99m Tc or 111 In is exemplified as a radionuclide that emits ⁇ -rays.
• the radioactive metal nuclide contained in the radioactive complex of the present invention is more preferably 225 Ac, 90 Y, 177 Lu, or 89 Zr.
• the concentration of the radioactive metal nuclide in the reaction solution is preferably 1 nmol at the start of the reaction between the radioactive metal nuclide and the ligand compound (hereinafter also referred to as "at the start of the complex formation step” or “at the start of the reaction”). /L or more and 10000 nmol/L or less, more preferably 1 nmol/L or more and 5000 nmol/L or less, still more preferably 1 nmol/L or more and 1000 nmol/L or less, and even more preferably 1 nmol/L or more and 500 nmol/L or less.
• the radioactive metal nuclide can be dissolved in a suitable solvent and stored in a solution state, and when necessary, the required amount can be taken out from this solution and used for the present invention.
• a solution for storing radioactive metal nuclides will also be referred to as a "bulk solution.”
• This bulk solution contains non-radioactive metals used in the production of radioactive metal nuclides.
• radionuclides should not be used immediately after production. preferable.
• the ligand compound used in the complex formation step has a structure represented by the following formula (1).
• R 11 , R 12 and R 13 are each independently -(CH 2 ) p COOH, -(CH 2 ) p C 5 H 4 N, -(CH 2 ) p PO 3 H 2 or -(CH 2 ) p CONH 2 .
• the above p is each independently an integer of 0 or more and 3 or less.
• one of R 14 or R 15 is a hydrogen atom, -(CH 2 ) p COOH, -(CH 2 ) p C 5 H 4 N, -(CH 2 ) p PO 3 H 2 , - It is a group consisting of (CH 2 ) p CONH 2 or -(CHCOOH)(CH 2 ) p COOH.
• the other of R 14 or R 15 is -(CH 2 ) p COOH, -(CH 2 ) p C 5 H 4 N, -(CH 2 ) p PO 3 H 2 , or -( CH 2 ) p CONH 2 or a reactive atomic group for linking with a targeting agent or a group linking with a targeting agent.
• the above p is each independently an integer of 0 or more and 3 or less. Details of the targeting agent and the reactive atomic group for linking with the targeting agent or the group linking with the targeting agent will be described later.
• the ligand compound used in the complex formation step includes one of the compounds shown below or a structure derived from the compound.
• the ligand compound used in the complex formation step is preferably water-soluble.
• DOTA (1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid)
• DOTMA ((1R, 4R, 7R, 10R)- ⁇ , ⁇ ', ⁇ '', ⁇ '''-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 ⁇ -(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
• the concentration of the ligand compound in the reaction solution at the start of the complex formation step is preferably 1 ⁇ mol/L or more and 1000 ⁇ mol/L or less, more preferably 1 ⁇ mol/L.
• the reaction solution in the complex formation step is an aqueous reaction solution containing water and a buffer.
• water water commonly used in this technical field can be used, and for example, distilled water or ion-exchanged water can be used.
• the buffer includes a water-soluble organic compound having a predetermined structure.
• the water-soluble organic compound is an organic compound that dissolves in water, and is a compound different from the above-mentioned ligand compound. Therefore, water-soluble organic compounds in this specification are not included in the ligand compounds.
• a water-soluble organic compound that has a predetermined structure and is not included in the ligand compound and the organic solvent is also referred to as a "second organic compound.”
• One of the characteristics of the second organic compound contained in the reaction solution is that it has a specific functional group in its structure.
• the second organic compound has a sulfo group in its structure.
• a sulfo group is a monovalent functional group represented by "--SO 3 H” or "--SO 3 - ".
• the second organic compound in this embodiment has one or two sulfo groups, that is, monosulfonic acid or disulfonic acid, which is easily available and can reduce production costs while allowing for the collection of radioactive metal complexes. This is preferable from the viewpoint of increasing the ratio.
• the total carbon number of the second organic compound is preferably 4 or more and 10 or less, more preferably 6 or more and 8 or less.
• the second organic compound has a sulfo group in its structure, it preferably has a hetero atom in its structure, it preferably has at least a nitrogen atom in its structure, and it preferably has a cyclohexane ring or a heterocycle in its structure. is more preferable, it is even more preferable that the structure contains a saturated heterocycle having two nitrogen atoms or a nitrogen atom and an oxygen atom, and it is even more preferable that the structure contains a morpholine ring or a piperazine ring.
• the structure has a sulfo group
• the structure has an alkanesulfonic acid group
• the structure has an aminoalkanesulfonic acid group. is more preferable.
• the second organic compound having a sulfo group in its structure is preferably an amphoteric ionic compound, and more preferably an aminoalkanesulfonic acid derivative.
• Examples of the second organic compound having one sulfo group in its structure include chain amine monosulfonic acids such as N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES); 2-morpholinoethanesulfone; monosulfonic acids with a morpholine ring such as acid (MES), 3-morpholinopropanesulfonic acid (MOPS); piperazine such as 2-[4-(2-hydroxyethyl)-1-piperazinyl]-ethanesulfonic acid (HEPES); Examples include monosulfonic acids having a ring; and/or salts thereof.
• chain amine monosulfonic acids such as N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES); 2-morpholinoethanesulfone; monosulfonic acids with a morpholine ring such as acid (MES), 3-morpholinopropanesulfonic acid (MOPS); piperazine such as 2-
• Examples of the second organic compound having two sulfo groups in its structure include 2-[4-(2-hydroxyethyl)-1-piperazinyl]-ethanesulfonic acid (HEPES), piperazine-1,4-bis( Examples include disulfonic acids having a piperazine ring in their structure, such as 2-ethanesulfonic acid (PIPES), and/or salts thereof.
• Counter ions for the second organic compound having a sulfo group in its structure include, for example, alkali metal ions such as sodium and potassium, cations such as ammonium and primary to quaternary ammonium such as tetramethylammonium salt, and chlorine. Examples include anions such as halogens.
• the second organic compound contained in the reaction solution has a carboxy group in its structure.
• the carboxyl group is a monovalent functional group represented by "-COOH” or "-COO - ".
• the second organic compound in this embodiment has one or two carboxyl groups and is a monocarboxylic acid or dicarboxylic acid, which is easily available and reduces the production cost while increasing the yield of the radioactive metal complex. It is preferable from the viewpoint of increasing the temperature.
• the total carbon number of the second organic compound is preferably 2 or more and 10 or less, more preferably 2 or more and 8 or less.
• the second organic compound is preferably a saturated or unsaturated aliphatic carboxylic acid or an aromatic carboxylic acid, and more preferably a saturated aliphatic carboxylic acid.
• Examples of the second organic compound having one carboxyl group in its structure include linear aliphatic monocarboxylic acids such as acetic acid and lactic acid; aromatic monocarboxylic acids such as benzoic acid and salicylic acid; and/or salts thereof. can be mentioned.
• Examples of the second organic compound having two carboxyl groups in its structure include linear aliphatic dicarboxylic acids such as malonic acid and tartaric acid, aromatic dicarboxylic acids such as phthalic acid; and/or salts thereof. .
• Examples of the counter ion of the second organic compound having a carboxyl group in its structure include alkali metal ions such as sodium and potassium, and cations such as ammonium and primary to quaternary ammonium such as tetramethylammonium salt. It will be done.
• the second organic compound having a sulfo group or a carboxy group in its structure is acetic acid, phthalic acid, malonic acid, or 2-[4-(2-hydroxyethyl)-1-piperazinyl]-ethanesulfonic acid, It is more preferable to use one or more selected from N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid, 2-morpholinoethanesulfonic acid, and salts thereof, and acetic acid or 2-[4-( It is more preferable to use one or more selected from 2-hydroxyethyl)-1-piperazinyl]-ethanesulfonic acid and salts thereof.
• a reaction solution containing a suitable second organic compound can be used in the complex formation step in a state that has been prepared in advance as an aqueous solution containing these organic compounds.
• these may be a buffer solution that exhibits a pH buffering effect, or may be a liquid that does not exhibit a pH buffering effect.
• the concentration of the second organic compound in the reaction solution is preferably 0.01 mol/L or more and 2.0 mol/L or less, and 0.1 mol/L at the start of the complex formation step. It is more preferable that the amount is 1.0 mol/L or more.
• the reaction solution may contain a stabilizer in addition to water and a buffer.
• the stabilizer contained in the reaction solution has a structure represented by the following formula (2) or a salt thereof.
• the stabilizers may be used alone or in combination.
• Adsorption of the radioactive metal or the target radioactive metal complex to the inner wall of the reaction vessel can be suppressed. As a result, the yield of the desired radioactive metal complex can be increased.
• R 21 is -COOH, -CH 2 COOH, -CH 2 OH, -COOR 28 , -CONH 2 or -CONHR 28 .
• one or more and three or less groups among R 22 to R 26 are hydroxy groups (-OH), and the other groups are hydrogen atoms.
• R 28 is substituted or unsubstituted alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted alkylaryl.
• R28 examples include a halogen atom, a saturated or unsaturated alkyl group, a hydroxy group, a formyl group, a carboxy group, an acyl group, an amino group, a nitro group, an ester group, an isothiocyanate group, and a thioxo group. , a cyano group, an amide group, an imide group, a phosphoric acid group, a phenyl group, a benzyl group, a pyridyl group, and the like. One of these substituents may be used alone, or two or more of these substituents may be used in combination.
• R 28 may be linear or branched, and may be saturated or unsaturated.
• the total carbon number of R28 is preferably 1 or more and 10 or less, more preferably 1 or more and 8 or less.
• examples of counter ions include alkali metal ions such as sodium and potassium, ammonium, and primary to quaternary ammonium such as tetramethylammonium salt. Examples include cations.
• Examples of the structure of the stabilizer represented by formula (2) include, but are not limited to, structures represented by any of the following formulas (2a) to (2g).
• R 28 is substituted or unsubstituted alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted alkylaryl.
• substituents that can be substituted on R28 include a halogen atom, a saturated or unsaturated alkyl group, a hydroxy group, a formyl group, a carboxy group, an acyl group, an amino group, a nitro group, an ester group, an isothiocyanate group, and a thioxo group.
• a cyano group an amide group, an imide group, a phosphoric acid group, a phenyl group, a benzyl group, a pyridyl group, and the like.
• One of these substituents may be used alone, or two or more of these substituents may be used in combination.
• One embodiment of the stabilizer represented by formula (2) includes a form in which R 21 is a carboxy group (-COOH). That is, the stabilizer in this form is hydroxybenzoic acid.
• the hydroxybenzoic acid represented by formula (2) include monohydroxybenzoic acid, dihydroxybenzoic acid, and trihydroxybenzoic acid.
• Examples of monohydroxybenzoic acid include the following forms.
• -2-Hydroxybenzoic acid (salicylic acid): In formula (2), R 21 is -COOH, R 22 is -OH, and R 23 to R 26 are all hydrogen atoms. This embodiment corresponds to equation (2a).
• -3-Hydroxybenzoic acid In formula (2), R 21 is -COOH, R 23 is -OH, and R 22 and R 24 to R 26 are all hydrogen atoms.
• -4-Hydroxybenzoic acid In formula (2), R 21 is -COOH, R 24 is -OH, and R 22 , R 23 , R 25 and R 26 are all hydrogen atoms.
• dihydroxybenzoic acid examples include the following forms.
• R 21 is -COOH
• R 22 and R 23 are both -OH
• R 24 to R 26 are all It is a hydrogen atom.
• R 21 is -COOH
• R 22 and R 24 are both -OH
• R 23 , R 25 and R 26 Both are hydrogen atoms.
• ⁇ 2,5-Dihydroxybenzoic acid (gentisic acid):
• R 21 is -COOH
• R 22 and R 25 are both -OH
• R 23 , R 24 and R 26 are all is also a hydrogen atom.
• This embodiment corresponds to equation (2b).
• ⁇ 2,6-dihydroxybenzoic acid ( ⁇ -resorcinic acid):
• R 21 is -COOH
• R 22 and R 26 are both -OH
• R 23 , R 24 and R 25 Both are hydrogen atoms.
• ⁇ 3,4-Dihydroxybenzoic acid protocatechuic acid:
• R 21 is -COOH
• R 23 and R 24 are both -OH
• R 22 , R 25 and R 26 are all is also a hydrogen atom.
• This embodiment corresponds to equation (2c).
• ⁇ 3,5-dihydroxybenzoic acid ⁇ -resorcinic acid:
• R 21 is -COOH
• R 23 and R 25 are both -OH
• R 22 , R 24 and R 26 Both are hydrogen atoms.
• trihydroxybenzoic acid examples include, but are not limited to, the following forms.
• R 21 is -COOH
• R 23 to R 25 are all -OH
• both R 22 and R 26 are is also a hydrogen atom.
• This embodiment corresponds to equation (2d).
• R 21 is -COOH
• R 22 , R 24 and R 26 are all -OH
• R 23 and R 25 are both It is a hydrogen atom.
• Another embodiment of the stabilizer represented by formula (2) includes a form in which R 21 is -CH 2 OH, -COOR 28 or -CONHR 28 .
• Compounds corresponding to this form include, for example, the following forms, but are not limited to this form.
• - Gentidyl alcohol In formula (2), R 21 is -CH 2 OH, R 22 and R 25 are all -OH, and R 23 , R 24 and R 26 are all hydrogen atoms. This embodiment corresponds to equation (2e).
• R 21 is -COOR 28 , R 22 and R 25 are all -OH, R 23 , R 24 and R 26 are all hydrogen atoms, R28 is a saturated linear alkyl group having 1 or more and 8 or less carbon atoms. This form is one form included in formula (2f).
• - Gentisic acid ethanolamide in formula (2), R 21 is -CONHR 28 , R 22 and R 25 are all -OH, R 23 , R 24 and R 26 are all hydrogen atoms, R 28 is -CH 2 -CH 2 OH. This form is one form included in formula (2g).
• compounds having structures represented by formulas (2a) to (2g) or salts thereof are preferably used as stabilizers, and formulas (2a) to It is more preferable to use a compound having a structure represented by any of formula (2d) or a salt thereof, and even more preferable to use a compound having a structure represented by formula (2b) or a salt thereof.
• the stabilizer is more preferably salicylic acid, gentisic acid, protocatechuic acid, or gallic acid, or a salt thereof, still more preferably salicylic acid, gentisic acid, protocatechuic acid, or a salt thereof, and gentisic acid or a salt thereof. is most preferable.
• the concentration of the stabilizer in the reaction solution at the start of the complex formation step is preferably 0.1 mmol/L or more and 500 mmol/L or less, and more Preferably it is 1 mmol/L or more and 400 mmol/L, more preferably 1 mmol/L or more and 300 mmol/L.
• the concentration of the stabilizer in the reaction solution is higher than the concentration of radioactive metal ions and the concentration of the ligand compound in the reaction solution, from the viewpoint of preventing radiolysis and further improving labeling efficiency. .
• a stabilizer is not essential in the present invention, it is preferable to add a stabilizer when using 89 Zr as a radioactive metal nuclide. This is because when using 89 Zr, the yield is likely to decrease due to the above-mentioned adsorption.
• the reaction solution used in the complex formation step may not contain an organic solvent, or an organic solvent may be added depending on the physical properties of the ligand compound and the stabilizer.
• organic solvents include protic solvents such as methanol and ethanol, and water-soluble aprotic solvents such as acetonitrile, N,N-dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, and acetone.
• protic solvents such as methanol and ethanol
• water-soluble aprotic solvents such as acetonitrile, N,N-dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, and acetone.
• the amount of reaction liquid in the complex formation step is not particularly limited, but from the viewpoint of practicality in the manufacturing process, it is realistically 0.01 mL or more and 100 mL or less at the start of the complex formation step.
• the radioactive metal source, the ligand compound, and the radioactive metal source are used.
• the order of addition of the ligand compound and other components does not matter. For example, one of the radioactive metal source and the ligand compound is added to a reaction vessel containing a mixed solvent prepared by mixing water, a stabilizer, and a second organic compound constituting the reaction solution, and then the other is added. It may be added and reacted.
• the radioactive metal source and the ligand compound may be added to a solution in which one of them is dissolved in a mixed solvent, and the other may be reacted.
• the radioactive metal source and the ligand compound may be simultaneously added to a reaction vessel containing a mixed solvent in advance for reaction.
• the reaction solution is irradiated with microwaves in order to further improve labeling efficiency in a short reaction time.
• microwave refers to electromagnetic waves with a frequency of 10 MHz to 300 GHz.
• the frequency of the irradiated microwave is preferably 800 MHz or more and 3 GHz or less, and more preferably 2.35 GHz or more and 2.55 GHz or less.
• the microwave irradiated to the reaction solution it is preferable to use, for example, a microwave oscillated using a magnetron-type or semiconductor-type microwave generator.
• the output of the microwave to be irradiated is preferably 10W or more, more preferably 30W or more.
• the microwave output is preferably 10 W or more, more preferably 30W or more.
• the microwave may be irradiated with a constant power during the complex formation step, or may be varied over time within the above-mentioned range. Further, during the complex formation step, the microwave may be irradiated continuously or intermittently. When irradiating microwaves continuously, the microwave irradiation time can be the same as the reaction time described below. When irradiating microwaves intermittently, the total microwave irradiation time is preferably 1 minute or more and 60 minutes or less, more preferably 5 minutes or more and 30 minutes or less.
• the temperature of the reaction solution is preferably 10°C or higher and 90°C or lower, more preferably 30°C or higher and 80°C or lower, and even more preferably 50°C or higher, from the viewpoint of both suppressing decomposition of the ligand compound and further improving labeling efficiency. °C or higher and 70°C or lower.
• the reaction time is preferably 1 minute or more and 60 minutes or less, more preferably 5 minutes or more and 30 minutes or less, provided that the reaction temperature is as described above.
• the reaction liquid is irradiated with microwaves while cooling the reaction liquid.
• cooling the reaction liquid includes embodiments in which the reaction liquid is directly cooled, and embodiments in which the reaction liquid is indirectly cooled by exposing the reaction container containing the reaction liquid to a cooling medium. do. From the viewpoint of operational simplicity, it is preferable to cool the reaction liquid indirectly. In an embodiment in which the reaction liquid is indirectly cooled, the temperature of the reaction liquid is maintained within the above range by simultaneously heating the reaction liquid by microwave irradiation and cooling the reaction liquid by a cooling medium. Adjust to.
• the degree of cooling of the reaction solution may be constant during the complex formation step, or may be changed over time during the complex formation step.
• Methods for changing the degree of cooling of the reaction liquid over time include, for example, changing the temperature of the cooling medium according to a predetermined schedule, and adjusting the temperature of the cooling medium according to the measured value of the temperature of the reaction liquid.
• the temperature of the reaction solution can be adjusted to the above range by keeping the degree of cooling constant and changing the output of the microwave irradiated over time within the above range. It may be kept within the range of . Alternatively, the temperature of the reaction solution may be maintained within the above range by changing both the microwave output and the degree of cooling over time.
• Microwave irradiation and cooling of the reaction solution may be carried out constantly during the complex formation reaction, or either one or both may be carried out intermittently, but from the viewpoint of increasing the microwave irradiation effect, Preferably, the wave is constantly irradiated during the complex formation reaction.
• microwave irradiation may be started before cooling the reaction solution, or cooling of the reaction solution may be started before microwave irradiation. Alternatively, both may be started at the same time. From the viewpoint of preventing the temperature of the reaction liquid from rising excessively, it is preferable to start cooling the reaction liquid first. However, if the temperature of the cooling medium is below the freezing point of the reaction solvent, it is preferable to start the microwave irradiation immediately after the start of cooling in order to prevent the reaction liquid from solidifying.
• cooling medium used when indirectly cooling the reaction liquid examples include gases such as air, liquids such as water and antifreeze, and solids such as aluminum blocks.
• gases such as air
• liquids such as water and antifreeze
• solids such as aluminum blocks.
• the temperature of the cooling medium is preferably -196°C or more and 90°C or less, more preferably -35°C or more and 25°C or less, and even more preferably -10°C or more and 0°C or less, from the viewpoint of facilitating adjustment of the temperature of the reaction liquid. It is.
• the complex formation step it is preferable to carry out the reaction in a state where the pH of the reaction solution is in an acidic region. That is, in the complex formation step, it is preferable to carry out the reaction while maintaining an acidic pH state from the start to the end of the reaction.
• the pH of the reaction solution being in the acidic region means that the pH of the reaction solution is less than 7.
• the pH of the reaction solution can be maintained in the acidic range even during the complex formation process by adjusting the pH of the reaction solution in the acidic range before the start of the reaction, that is, before the implementation of the complex formation process. can.
• the pH of the reaction solution can be adjusted, for example, by mixing an aqueous solution of the second organic compound and/or a stabilizer into the reaction solution.
• the pH of the reaction solution can be adjusted by adjusting the mixing ratio of these aqueous solutions. Can be adjusted.
• an inorganic acid such as hydrochloric acid or a metal hydroxide such as sodium hydroxide may be added to a liquid mixture of a radioactive metal ion, a ligand compound, a second organic compound, and a stabilizer. It is also possible to adjust the pH.
• the amount of radioactivity of the radioactive metal nuclide in the reaction solution at the start of the reaction is set as follows from the viewpoint of improving the production efficiency of the radioactive metal complex.
• the amount of radioactivity in the reaction solution at the start of the reaction of the complex formation step is 5 MBq or more, preferably 15 MBq or more, more preferably 50 MBq or more . .
• the amount of radioactivity in the reaction solution at the start of the reaction in the complex formation step is 1 MBq or more, preferably 2 MBq or more, more preferably 4 MBq or more . .
• the upper limit of the amount of radioactivity in the reaction solution at the start of the reaction is not particularly limited as long as it is an amount of radioactivity that can be realized on a commercial production scale, but may be, for example, 1000 GBq or less. .
• the amount of ligand compounds used can be reduced by setting the ratio between the amount of radioactivity of the radioactive metal nuclide and the amount of ligand compounds in the reaction solution at the start of the reaction to the value described below.
• the radioactive amount of the radioactive metal nuclide per 1 nmol of the ligand compound is preferably 10 MBq as a ratio between the ligand compound and the radioactive amount in the reaction solution at the start of the reaction.
• the radioactivity of the radiometal nuclide per 1 nmol of the ligand compound is preferably 0 as the ratio between the ligand compound and the radioactivity in the reaction solution at the start of the reaction. .3 MBq or more, more preferably 1 MBq or more, still more preferably 2 MBq or more.
• the radioactivity of the radiometal nuclide per 1 nmol of the ligand compound is preferably 0 as the ratio between the ligand compound and the radioactivity in the reaction solution at the start of the reaction. .3 MBq or more, more preferably 1 MBq or more, still more preferably 2 MBq or more.
• the complex-forming reaction is effectively promoted by microwave irradiation. Therefore, even when the amount of radioactivity of the radioactive metal nuclide per nmol of the ligand compound is increased to the above range, the complex formation reaction proceeds in high yield.
• the reaction pressure in the complex formation step can be atmospheric pressure.
• the manufacturing method of the present invention which includes the complex formation step described above, performs the complex formation reaction while irradiating sufficiently high-power microwaves, so it is different from the conventional technology of heating without microwave irradiation and the microwave irradiation conditions.
• the rate of progress of the complex formation reaction can be increased compared to conventional techniques in which the complex formation reaction is not optimized. This makes it possible to produce radioactive metal complexes in high yield even with short reaction times.
• by irradiating the reaction liquid with microwaves while cooling the reaction liquid it is possible to prevent the temperature of the reaction liquid from rising excessively while increasing the output of the irradiated microwaves. can.
• the production method of the present invention has a high yield of the obtained radioactive metal complex, it is also advantageous in that the complex can be subjected to subsequent steps without separating and purifying unreacted radioactive metal nuclides. .
• R 11 , R 12 and R 13 are Both are preferably carboxyalkyl groups represented by a group consisting of -(CH 2 ) p COOH, where p is an integer of 1 or more and 3 or less.
• one of R 14 and R 15 is a hydrogen atom or a carboxyalkyl group represented by a group consisting of -(CH 2 ) p COOH, where p is an integer of 1 to 3. is also preferable.
• the other of R 14 and R 15 is a carboxyalkyl group represented by a group consisting of -(CH 2 ) p COOH, where p is an integer of 1 to 3, or is linked to a targeting agent. It is also preferable that it is a reactive atomic group or a linked group.
• R 11 , R 12 , R 13 , R 14 and R 15 have the above-mentioned suitable groups, when one of R 14 and R 15 is a hydrogen atom, the other of R 14 and R 15 is a targeting group. It is preferably a reactive atomic group for linking with an agent or a group linking with a targeting agent.
• R 14 when R 14 is a reactive atomic group for coupling with a targeting agent or a group linked to a targeting agent, R 15 is a hydrogen atom, and R 15 is a reactive atomic group for coupling with a targeting agent or a group linked to a targeting agent.
• R 14 is preferably a hydrogen atom.
• the targeting agent when a ligand compound containing a group linked to a targeting agent is used, the targeting agent may include a low molecular compound, polypeptide, peptide aptamer, growth factor, affibody, unibody, nanobody, monobody, etc.
• it is one or more types of atomic groups including those selected from saccharides, polysaccharides, vitamins, nucleic acids, liposomes, micelles, carbon nanotubes, and nanoparticles.
• the targeting agent is more preferably a low molecular compound, a polypeptide, or a nucleic acid.
• the low-molecular compound is, for example, a compound having a structure having target-directedness or an atomic group capable of a click reaction.
• targeting agent refers to a chemical structure for expressing tropism toward a target organ or tissue in a living body or specificity for a target molecule.
• a target organ or tissue or a target molecule is also collectively referred to as a "target site.”
• These targeting agents may be bound directly to the ligand compound or indirectly through other known linker structures such as PEG.
• these targeting agents may be configured to be able to be linked to a ligand compound using modified reactive atomic groups that can be bonded to other structures.
• a known reaction such as a click reaction can be employed.
• the reactive atomic group of the targeting agent and the reactive atomic group of the ligand compound for linking with the targeting agent are both groups containing an atomic group capable of a click reaction. can do.
• a ligand compound having such a chemical structure it is possible to easily bind a targeting agent that has specificity or directivity to the target site, and also to ensure that the specificity or directivity of the targeting agent to the target site is sufficiently high.
• a radioactive metal complex having specificity or directivity to a target site can be obtained in high yield while maintaining the target site.
• the targeting agent when the targeting agent includes a polypeptide, the targeting agent is preferably a chain peptide, a cyclic peptide, a combination thereof, or a protein that specifically binds to a specific molecule.
• atomic groups include peptides comprising three or more amino acid residues.
• the molecular weight of the peptide is preferably 500 or more and 20,000 or less, more preferably 1,000 or more and 6,000 or less, from the viewpoint of chemically controlled synthesis.
• the polypeptide may also be an antibody or a fragment thereof.
• Examples include antibodies (immunoglobulins) having the classes IgG, IgA, IgM, IgD and IgE, antibody fragments such as Fab fragments and F(ab') 2 fragments, peptide aptamers, and the like.
• the amino acids constituting the above-mentioned targeting agent may be natural or synthetic.
• polypeptides that can be used as targeting agents can be synthesized by conventionally known methods, such as liquid phase synthesis, solid phase synthesis, automated peptide synthesis, genetic recombination, phage display, genetic code reprogramming, and RaPID (Random It can be synthesized by a method such as a non-standard Peptide Integrated Discovery method.
• the functional groups of the amino acids used may be protected as necessary.
• the targeting agent is an atomic group containing a nucleic acid
• the atomic group is an atomic group containing an antisense nucleic acid, siRNA, miRNA, nucleic acid aptamer, decoy nucleic acid, cPG oligonucleic acid, or peptide nucleic acid that specifically binds to a specific molecule. It is preferable that there be.
• the nucleobase constituting such a targeting agent may be a natural one such as deoxyribonucleic acid or ribonucleic acid, or a synthetic one.
• the atomic group containing the above-mentioned nucleic acid that can be used in the present invention can be produced by a conventionally known method.
• a nucleic acid aptamer a nucleic acid aptamer that specifically binds to a specific target substance such as a protein can be produced using the SELEX method (Systematic Evolution of Ligands by Exponential Enrichment).
• the atomic group capable of a click reaction is Those derived from usable known reagents can be used as appropriate.
• the term "reactive atomic group" as used herein refers to a chemical structure in which a reaction occurs directly when one compound is bonded to another compound. Examples of such reactive atomic groups include, but are not limited to, atomic groups capable of a click reaction.
• the atomic group capable of a click reaction examples include an alkynyl group or an azide group, or a diene or dienophile such as a 1,2,4,5-tetrazine or alkenyl group. From the viewpoint of simplifying the click reaction process, it is preferable that the atomic group capable of a click reaction as a reaction atomic group is an atomic group that can be used for a metal catalyst-free click reaction.
• the click reaction is, for example, a reaction caused by a combination of an alkyne and an azide, or a combination of a diene such as 1,2,4,5-tetrazine and an alkene and a dienophile.
• a combination of atomic groups include the Husgen cycloaddition reaction and the Diels-Alder reaction.
• the chemical structure formed by the click reaction of a combination of an alkyne and an azide contains a triazole skeleton
• the combination of a diene and a dienophile is a combination of a 1,2,4,5-tetrazine and an alkene.
• the chemical structure produced by the click reaction in contains a pyridazine skeleton. Therefore, as long as the atomic group that can be included in the reaction atomic group for linking with the targeting agent and is capable of a click reaction includes an alkyne or an azide, a triazole skeleton can be formed by a click reaction.
• an atomic group containing 1,2,4,5-tetrazine or an alkene, which is a diene or dienophile is included as a click-reactable atomic group that can be included in the reaction atomic group for linking with a targeting agent, click reaction is possible.
• a pyridazine skeleton can be formed by the reaction.
• atomic groups capable of click reaction include, as shown in the following formula, an atomic group containing dibenzylcyclooctyne (DBCO) as an alkyne (formula (5a)), an atomic group containing an azide group as an azide (formula (5b)), an atomic group containing 1,2,4,5-tetrazine (formula (5c)), or an atomic group containing trans-cyclooctene (TCO) as an alkene (formula (5d)).
• DBCO dibenzylcyclooctyne
• TCO trans-cyclooctene
• R 1 represents a bonding site with an atomic group containing a ligand compound or a targeting agent.
• R 2 represents a bonding site with an atomic group containing a ligand compound or a targeting agent.
• one of R 3 and R 4 represents a bonding site with a ligand compound or an atomic group containing a targeting agent, and the other represents a hydrogen atom, a methyl group, a phenyl group, or a pyridyl group.
• R 5 represents a bonding site with an atomic group containing a ligand compound or a targeting agent.
• DBCO dibenzylcyclooctyne
• DBCO-C6-Acid DBCO-Amine
• DBCOMaleimide DBCO-PEG acid
• DBCO -PEG-NHS ester DBCO-PEG-Alcohol
• DBCO-PEG-amine DBCO-PEG-NH-Boc
• Carboxyrhodamine-PEG-DBCO Sulforhodamine-PEG-DBCO
• TAMRA- PEG-DBCO DBCO-PEG-Biotin
• DBCO reagents such as DBCO-PEG-DBCO, DBCO-PEG-Maleimide, TCO-PEG-DBCO, DBCO-mP
• Suitable ligand compounds used in the present invention include, but are not limited to, those having structures shown in the following formulas (1-a) to (1-e). Regardless of the structure of the ligand compound, the effect of stably improving the labeling rate is sufficiently exhibited.
• P represents an atomic group containing a reactive atomic group or an atomic group containing a targeting agent. From the viewpoint of stably improving the labeling rate, a ligand compound having a structure represented by the above formula (1-c) is more preferably used.
• the ligand compound and the atomic group capable of a click reaction can be indirectly linked by the linker structure shown in the following formula (P). It is also preferable that they are bonded.
• the structure is derived from ethylene glycol, and in formula (P), n is preferably an integer of 2 or more and 10 or less, more preferably an integer of 2 or more and 8 or less.
• the structure of the ligand compound containing an atomic group capable of a click reaction is not particularly limited as long as the effects of the present invention are achieved, but it is more preferable to have the structure shown below. That is, it is more preferable that the ligand compound has at least one of the following DO3A-DBCO, DOTA-DBCO, DO3A-PEG4-DBCO, DO4A-PEG7-Tz, and DOTAGA-DBCO.
• a ligand compound containing an atomic group capable of a click reaction is used as a reactive atomic group
• the ligand compound is coordinated to a radioactive metal nuclide by the method described above, and then the ligand compound has A radioactive metal complex can be produced by reacting an atomic group capable of a click reaction with an atomic group capable of a click reaction in a targeting agent by a click reaction or the like.
• a compound modified with an atomic group capable of a click reaction that specifically binds to a reactive atomic group in the ligand compound can be used as the targeting agent.
• the click-reactable atomic group that modifies the targeting agent the same ones as mentioned above can be used.
• the radioactive metal complex produced through the above steps exists in a dissolved state in the reaction solution. That is, the radioactive metal complex can be obtained as an aqueous liquid.
• the aqueous liquid containing the radioactive metal complex may be used as it is, or may be purified using a filtration filter, a membrane filter, a column packed with various fillers, chromatography, or the like.
• the steps after obtaining the radioactive metal complex include, for example, a formulation step for obtaining a radiopharmaceutical containing the radioactive metal complex as an active ingredient.
• various stabilizers such as pH adjusters such as citrate buffer, phosphate buffer, and borate buffer, solubilizers such as polysorbate, stabilizers or antioxidants may be added as appropriate. This can be done by adjusting the radioactivity concentration by diluting it with an isotonic solution such as water or physiological saline.
• the formulation step may include a step of adding various stabilizers or adjusting the concentration, followed by sterilization filtration using a membrane filter or the like to prepare an injection.
• Radioactive metal nuclide A complex forming step of reacting the ligand compound represented by the above formula (1) in a reaction solution containing water and a buffer to form a radioactive metal complex,
• the buffer agent contains one or more water-soluble organic compounds having a sulfo group or a carboxy group,
• a method for producing a radioactive metal complex wherein in the complex forming step, the reaction solution is irradiated with microwaves while cooling the reaction solution.
• 89 Zr, DOTAGA-DBCO, and gentisic acid were used as the radioactive Zr element, the ligand compound, and the stabilizer, respectively. Furthermore, acetic acid and sodium acetate were used as the second organic compound.
• 89 Zr was extracted from a bulk solution of 89 Zr ions and used. The following lots A to D were used as bulk solutions of 89 Zr io. Lot A: 3.9 GBq of 89 Zr bulk solution 4 days after production. Lot B: 11.8 GBq of 89 Zr bulk solution one day after production. Lot C: 8.8 GBq of 89 Zr bulk solution 4 days after production. Lot D: 8.8 GBq of 89 Zr bulk solution 6 days after production.
• reaction results of the complex formation reaction are affected by the lot of the bulk solution, comparisons of the reaction results of each example and comparative example are performed using the same lot. It is necessary to carry out between examples and comparative examples.
• Example 1 (Preparation of reaction solution) 0.1 mL of a bulk solution of 89 Zr ions (Lot A, solvent: 1.0 mol/L hydrochloric acid) was dispensed into a 2 mL vial, and the amount of radioactivity was measured using a radioisotope dose calibrator (manufactured by CAPINTEC). The amount of radioactivity measured was 1491 MBq. Next, the vial was heated at 110° C. for 40 minutes under an argon stream to distill off the solvent.
• solution 2 a 0.156 mol/L acetic acid-sodium acetate buffer
• solution 3 a 0.156 mol/L acetic acid-sodium acetate buffer
• the radioactivity of 89 Zr (hereinafter also referred to as "specific radioactivity") per nmol of the ligand compound (DOTAGA-DBCO) contained in this reaction solution was 3.6 MBq/nmol, and the volume of the reaction solution was 600 ⁇ L.
• TLC thin layer chromatography
• the labeling rate indicates the degree of progress of the labeling reaction, and the higher the labeling rate, the more the target 89 Zr complex is produced, which means that the labeling reaction is proceeding favorably.
• the labeling rate of this sample was 91%.
• the adsorption rate (%) of the 89 Zr complex was calculated based on the amount of adsorption confirmed by measuring the amount of radioactivity in the reaction container from which the reaction solution was taken out using a radioisotope dose calibrator (manufactured by CAPINTEC).
• the adsorption rate indicates the ratio of the radioactivity of 89 Zr adsorbed to the inner wall of the reaction vessel to the charged radioactivity.
• the adsorption rate of this sample was 19%.
• Theoretical yield (%) labeling rate (%) x (100 - adsorption rate (%)) / 100
• the theoretical yield calculated by the above formula indicates the ratio of the 89 Zr complex that can be taken out and used from the reaction vessel to the amount of 89 Zr charged.
• the theoretical yield of this sample was 74%.
• Examples 2 to 6, Comparative Examples 1 to 7 89
• the bulk solution lot of Zr ions, the radioactivity to be prepared, the amount of solutions 1 to 3 added, the concentration of the ligand compound DOTAGA-DBCO contained in solution 3, the reaction time, and the heating method were as shown in Table 1. Except for this, 89 Zr complexes of Examples 2 to 6 and Comparative Examples 1 to 7 were produced in the same manner as in Example 1. Table 1 shows these labeling rates, adsorption rates, and theoretical yields.
• the reaction solution was heated using a block heater without irradiating the microwave. This also applies to Comparative Examples 8 to 10, which will be described later.
• the semiconductor type microwave generator is referred to as "semiconductor type MW" in Table 1 and Tables 2 and 4 described later.
• Examples 7 to 10, Comparative Example 8 89
• the procedure was carried out except that the lot of the bulk solution of Zr ions, the radioactivity to be prepared, the amount of solutions 1 to 3 added, the concentration of the ligand compound DOTAGA-DBCO contained in solution 3, and the heating method were as shown in Table 2.
• 89 Zr complexes of Examples 7 to 10 and Comparative Example 8 were produced. Table 2 shows these labeling rates, adsorption rates, and theoretical yields.
• the magnetron type microwave generator is referred to as "magnetron type MW" in Table 2 and Table 3 described later. Further, as the magnetron type microwave generator, Discover manufactured by CEM was used.
• Examples 11-14, Comparative Examples 9-10 89
• the procedure was the same as in Example 1, except that the lot of the bulk solution of Zr ions, the radioactivity to be prepared, the amount of solutions 1 to 3 added, the reaction time, the heating method, and the maximum output of microwave were as shown in Table 3.
• 89 Zr complexes of Examples 11 to 14 and Comparative Examples 9 to 10 were produced. Table 3 shows these labeling rates, adsorption rates, and theoretical yields.
• Examples 11 to 14 in which the reaction was carried out with the maximum microwave output of 20 to 100 W, the target 89 Zr complex had a higher theoretical level than in Comparative Example 9, in which the reaction was performed with a block heater without irradiation with microwaves. Obtained in yield. Microwaves had the highest theoretical yield of 89 Zr complex especially when the maximum output was 60W.
• Examples 11 to 13 in which the reaction was performed for 10 minutes at a maximum microwave output of 40 to 100 W, had higher theoretical yields than Comparative Example 10, in which the reaction was performed for 60 minutes without irradiation with microwaves. It can be seen from these reaction conditions that the reaction time could be shortened to 1/6 or less compared to the case without microwave irradiation.
• Example 15-16 89
• the lot of the bulk solution of Zr ions, the radioactivity to be prepared, the addition amount of solutions 1 to 3, the heating method, and the maximum output of microwaves are as shown in Table 4, and the microwave irradiation is turned ON/OFF for 10 seconds.
• the 89 Zr complex of Example 15 was produced in the same manner as in Example 1 except that the 89 Zr complex was changed in each case. Further, in Example 16, the 89 Zr complex of Example 16 was produced in the same manner as in Example 15 except that Solution 2 not containing gentisic acid as a stabilizer was used. Table 4 shows these labeling rates, adsorption rates, and theoretical yields.
• Example 16 in which gentisic acid was not used, the adsorption rate was higher and the theoretical yield was lower than in Example 15, in which gentisic acid was used. That is, in the present invention, by combining the effect of promoting the complex formation reaction by microwave irradiation and the effect of suppressing the adsorption of the radioactive metal complex by the stabilizer, it is possible to produce the radioactive metal complex even more efficiently. Become.

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