Patent Application
20240293586
The present invention relates to a radiolabeled compound useful as a therapeutic agent and/or diagnostic agent for prostate cancer, and a method for producing the same.
Prostate cancer is the most common cancer among men and has a good prognosis if detected early (5-year survival rate is over 95%). Initial treatment is total or partial resection of the primary tumor or radiation therapy. Hormone therapy using drugs is also an effective treatment method. However, recurrence or metastasis often occurs over time. After recurrence, hormone therapy is once successful, but it gradually becomes resistant, leading to castration-resistant prostate cancer (CRPC), especially metastasis castration-resistant prostate cancer (mCRPC), which is extremely difficult to treat. The development of effective drugs for the treatment and diagnosis of such CRPC is desired.
Prostate-specific membrane antigen (PSMA) is attracting attention as a target molecule for prostate cancer. PSMA is highly expressed not only in the primary prostate cancer, but also in recurrent lesions and in metastases in lymph nodes and bones. Therefore, it is suggested that drugs that bind specifically to PSMA may be effective in the treatment and diagnosis of CRPC and mCRPC. Since PSMA is also expressed in the kidneys and salivary glands in normal tissues, it is important that drugs that bind specifically to PSMA do not show side effects due to accumulation in the kidneys and salivary glands.
Drugs labeled with 177Lu (β-ray emitting nuclide) or 225Ac (α-ray emitting nuclide) that target PSMA have been reported (Patent Document 1). Although the former drug shows a certain degree of effectiveness in treating CRPC patients, it is known that there are still cancer patients who cannot be treated with this drug. The latter drug, which is expected to have a stronger therapeutic effect, has been reported to have side effects on the salivary glands, and has also been suggested to have side effects on renal function due to progeny nuclides.
Since 211At, the same α-ray emitting nuclide as 225Ac, has a shorter half-life than 225Ac (211At: 7.2 hours, 225Ac: 10 days), drugs labeled with 211At have short action times and can be treated on an outpatient basis. Furthermore, since it is a short-lived nuclide, it also has the advantage of lower risk of prolonged side effects, and is expected to be useful as a new anticancer drug.
Various drugs labeled with 211At (α-ray emitting nuclide) that target PSMA have been reported (Patent Documents 2 and 3, Non-Patent Documents 1 and 2). However, there are problems with optimization of pharmacokinetics and side effects due to kidney accumulation, and no drug has progressed to the clinical trial stage at this time.
Drugs labeled with 18F that target PSMA have been reported to be useful as PET imaging diagnostic agents (Patent Document 4).
The aims of the present invention are to provide an agent that binds specifically to PSMA, is effective in the treatment and diagnosis of tumors or cancers expressing PSMA, for example, the treatment and diagnosis of prostate cancer, especially castration-resistant prostate cancer (CRPC), further especially metastatic castration-resistant prostate cancer (mCRPC), and does not exhibit side effects due to accumulation in the kidney or salivary glands.
The present inventors have conducted intensive studies in an attempt to solve the above-mentioned problems and found that a novel radiolabeled compound represented by the following Formula (I) binds specifically to PSMA, is effective in the treatment and diagnosis of tumors or cancers expressing PSMA, for example, the treatment and diagnosis of prostate cancer, especially castration-resistant prostate cancer (CRPC), further especially metastatic castration-resistant prostate cancer (mCRPC), and does not exhibit side effects due to accumulation in the kidney or salivary glands, which resulted in the completion of the present invention.
Accordingly, the present invention provides the following.
[1] a radiolabeled compound represented by Formula (I) or a pharmaceutically acceptable salt thereof (hereinafter to be also referred to as Radiolabeled Compound (I)):
According to the present invention, a radiolabeled compound that binds specifically to PSMA, is effective in the treatment and diagnosis of tumors or cancers expressing PSMA, for example, the treatment and diagnosis of prostate cancer, especially castration-resistant prostate cancer (CRPC), further especially metastatic castration-resistant prostate cancer (mCRPC), and does not exhibit side effects due to accumulation in the kidney or salivary glands, can be provided.
The present invention is explained in detail in the following.
In the present specification, examples of the “C1-3 alkyl group” include methyl, ethyl, propyl and isopropyl.
In the present specification, examples of the “C1-6 alkyl group” include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neo-pentyl, 1-ethylpropyl, hexyl, isohexyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl and 2-ethylbutyl. The preferred is “C1-3 alkyl group”.
In the present specification, examples of the “C6-14 aryl group” include phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl and 9-anthryl.
In the present specification, the “amino acid residue” means a divalent group obtained by removing H from the amino group and OH from the carboxy group of an amino acid. The amino acid of the amino acid residue is not particularly limited as long as it has an amino group and a carboxy group, and it may be a natural type (L-type) or an unnatural type (D-type) amino acid, or may be an artificial amino acid. Further, the amino acid may be an α-amino acid, a β-amino acid, a γ-amino acid or the like. It may be a cyclic amino acid as shown below.
wherein each symbol in the formulas is as defined above.
Examples of the α-amino acid include glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, glutamic acid, aspartic acid, lysine, arginine, histidine, glutamine, asparagine, phenylalanine, tyrosine, α-methyltyrosine, tryptophan, ornithine, thyroxine, proline, 3,4-dihydroxyphenylalanine, 3-(1-naphthyl)alanine, 3-(2-naphthyl)alanine, α-aminobutyric acid, norvaline, norleucine, homonorleucine, 1,2,4-triazole-3-alanine, 2-aminoadipic acid, propargylglycine, allylglycine, α-cyclobutylmethylglycine, 6-azidonorleucine, 4-azidophenylalanine, 4-fluoroglutamic acid, 4-iodophenylalanine and the like;
Examples of the β-amino acid include β-alanine, 3-aminoadipic acid and the like;
Examples of the γ-amino acid include γ-aminobutyric acid and the like. When the amino acid has a functional group in its side chain, the functional group may be protected/modified.
In the present specification, the “boryl group (—B(OH)2)” is also referred to as a dihydroxyboryl group.
In the present specification, examples of the “ester group of a boryl group” include the following groups.
wherein R4 is a C1-6 alkyl group.
In the present specification, the “protected amino acid residue” means an amino acid residue whose functional group is protected when the amino acid residue has a functional group. When it has an amino group, it is protected with an amino-protecting group such as a tert-butoxycarbonyl group (Boc group), and when it has a carboxyl group, it is protected with a carboxy-protecting group such as a tert-butyl group. These protecting groups are appropriately selected depending on the type of other protecting groups and resin for solid phase synthesis, the synthesis strategy, and the like.
In the present specification, the “protected hydroxy group” is a hydroxy group protected by a “hydroxy-protecting group”, and examples of the “hydroxy-protecting group” include a benzyl group, a p-methoxybenzyl group, a methoxymethyl group, a trimethylsilyl group, a triethylsilyl group, a trityl group, a tert-butyl group, a tert-butyldimethylsilyl group, a tetrahydropyranyl group and the like.
In the present specification, the “protected amino group” is an amino group protected by an “amino-protecting group”, and examples of the “amino-protecting group” include a 9-fluorenylmethyloxycarbonyl group (Fmoc group), Boc group, a benzyloxycarbonyl group (Cbz group) and the like.
In the present specification, examples of the “carboxy-protecting group” include a tert-butyl group, a benzyl group, a C1-2 alkyl group (a methyl group, an ethyl group), diphenylmethyl group and the like.
Radiolabeled Compound (I) of the present invention is the compound shown below.
wherein each symbol in the formula is as defined above.
—CO-A1-NH— in the number of p1 are each independently an amino acid residue.
In one embodiment, the amino acid residue is preferably a glutamic acid residue (Glu).
In one embodiment, at least one of the amino acid residues in the number of p1 is preferably a glutamic acid residue.
In another embodiment, at least two of the amino acid residues in the number of p1 are preferably glutamic acid residues.
The configuration of the amino acid residue is not particularly limited, and may be any of D-form, L-form and DL-form (that is, any of R-form, S-form and R/S-form).
p1 is an integer of 0 to 3.
In one embodiment, p1 is preferably an integer of 0 to 2.
In one embodiment, —(CO-A1-NH)p1- is preferably a single bond, or -L-Glu-L-Glu- or -D-Glu-D-Glu-.
—CO-A2-NH— in the number of p2 are each independently an amino acid residue.
In one embodiment, the amino acid residue is preferably a glycine residue (Gly).
In one embodiment, at least one of the amino acid residues in the number of p2 is preferably a glycine acid residue.
The configuration of the amino acid residue is not particularly limited, and may be any of D-form, L-form and DL-form (that is, any of R-form, S-form and R/S-form).
p2 is an integer of 0 to 3.
In one embodiment, p2 is preferably 0 or 1.
In one embodiment, —(CO-A2-NH)p2- is preferably a single bond, or -Gly-.
L1 is a single bond, or —CO—(CH2)m1—CO— wherein m1 is an integer of 1 to 6.
In one embodiment, m1 is preferably 2 or 3, particularly preferably 2.
L2 is a single bond, or —NH—(CH2)m2—CH(COOH)—NH— wherein m2 is an integer of 1 to 6.
In one embodiment, m2 is preferably an integer of 3 to 5, particularly preferably 4.
The preferred combinations of L1 and L2 include
R1 in the number of q are each independently a hydrogen atom, a C1-6 alkyl group (e.g., methyl) or an amino group.
In one embodiment, R1 is preferably a hydrogen atom.
R2 in the number of q are each independently a hydrogen atom or a C1-6 alkyl group (e.g., methyl).
In one embodiment, R2 is preferably a hydrogen atom.
q is an integer of 0 to 3.
In one embodiment, q is preferably an integer of 1 to 3, more preferably 1.
Ar is a C6-14 aryl group.
In one embodiment, Ar is preferably a phenyl group.
R3 in the number of n are each independently a C1-6 alkyl group (e.g., methyl) or a hydroxy group.
n is an integer of 0 to 3.
In one embodiment, n is preferably 0.
X is a radionuclide selected from 211At (α-ray emitting nuclide), 210At (α-ray emitting nuclide), 131I (β-ray emitting nuclide), 125I (X-ray emitting nuclide), 124I (positron emitting nuclide), 123I (γ-ray emitting nuclide), 77Br (auger electron emitting nuclide) and 76Br (positron emitting nuclide).
The half-lives of these radionuclides are 7.2 hours for 211At, 8.3 hours for 210At, 8.04 days for 131I, 59.4 days for 125I, 4.2 days for 124I, 13.2 hours for 123I, 57 hours for 77Br, and 16 hours for 76Br.
The bonding position of X on Ar is not particularly limited. For example, when Ar is a phenyl group, the bonding position of X is preferably the 3-position or the 4-position.
The configuration of the naphthyl alanine residue in Formula (I)
is not particularly limited, and may be any of D-form, L-form and DL-form (that is, any of R-form, S-form and R/S-form).
The configuration of the lysine-glutamic acid residue in Formula (I)
is not particularly limited, and may be any of the following configurations.
In one embodiment, the lysine-glutamic acid residue is preferably
That is, Compound (I) is preferably Compound (Ia) shown below.
wherein each symbol in the formula is as defined above.
Specific examples of Radiolabeled Compound (I) include the followings.
wherein X is as defined above.
A compound represented by Formula (I) may be in the form of a pharmaceutically acceptable salt thereof. As the pharmaceutically acceptable salt, for example, when the compound has an acidic functional group, examples of the salt include inorganic salts such as alkali metal salts (e.g., sodium salt, potassium salt, etc.), alkaline-earth metal salts (e.g., calcium salt, magnesium salt, barium salt, etc.) and ammonium salt, and when the compound has a basic functional group, examples of the salt include salts with inorganic acids such as hydrogen chloride, hydrobromic acid, nitric acid, sulfuric acid and phosphoric acid, and salts with organic acids such as acetic acid, phthalic acid, fumaric acid, oxalic acid, tartaric acid, maleic acid, citric acid, succinic acid, methanesulfonic acid and p-toluenesulfonic acid.
The chiral C atom in Radiolabeled Compound (I) may be in D-configuration or in L-configuration. Radiolabeled Compound (I) has optical isomers based on the chiral C atom, and any optical isomer and mixture thereof in any proportion are also included in Radiolabeled Compound (I).
A method for producing Radiolabeled Compound (I) of the present invention will be explained below.
In the present specification, when a raw material compound is in the form of a salt, examples of such salt include metal salts (e.g., alkali metal salts such as sodium salt and potassium salt; and alkaline-earth metal salts such as calcium salt, magnesium salt and barium salt), ammonium salts, salts with organic bases (e.g., trimethylamine, triethylamine, pyridine, picoline, 2,6-lutidine), salts with inorganic acids (e.g., hydrochloric acid, hydrobromic acid, nitric acid, sulfuric acid), salts with organic acids (e.g., formic acid, acetic acid, trifluoroacetic acid, phthalic acid, fumaric acid, oxalic acid, tartaric acid, maleic acid, citric acid, succinic acid, malic acid), and the like.
Radiolabeled Compound (I) can be produced by the following method comprising Step 1.
wherein each symbol in the formula is as defined above.
Y is a boryl group (—B(OH)2) or its ester group.
Y is preferably a boryl group (—B(OH)2) or a 4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl group (a pinacol ester group).
Step 1 is a step of reacting Boronic Acid Compound (II) with a radionuclide selected from 211At, 210At, 131I, 125I, 124I, 123I, 77Br and 76Br in the presence of a reagent selected from an alkali metal iodide, an alkali metal bromide, N-bromosuccinimide, N-chlorosuccinimide, N-iodosuccinimide and hydrogen peroxide, in water to obtain Radiolabeled Compound (I).
Boronic Acid Compound (II) is a novel compound.
In one embodiment, Boronic Acid Compound (II) is preferably Boronic Acid Compound (IIa) shown below.
wherein each symbol in the formula is as defined above.
Specific examples of Boronic Acid Compound (II) include the followings.
Boronic Acid Compound (II) can be produced by the method described below.
Since the reaction in this step is carried out in water, Boronic Acid Compound (II) may be in a free form or salt form as long as it can be dissolved in water. Alternatively, it may be used in the form of a solution prepared by dissolving in a weakly basic aqueous solution such as an aqueous sodium hydrogen carbonate solution.
Examples of the alkali metal iodide include potassium iodide, sodium iodide and the like. Among them, potassium iodide is preferably used.
Examples of the alkali metal bromide include sodium bromide, potassium bromide and the like.
The preferred combinations of the radionuclide and the above reagent include
As the preferred embodiment, the radionuclide is 211At or 131I, and the reagent is selected from potassium iodide and N-bromosuccinimide.
The more preferred embodiments include
The above reagent is used in an amount sufficient to oxidize or reduce the radionuclide, and is used usually in a large excess amount relative to the radionuclide. It is used preferably in a concentration of 0.0001 to 0.2 mol/L, more preferably in a concentration of 0.001 to 0.1 mol/L, in terms of reaction efficiency and economic efficiency.
For the reaction, the radionuclide is used usually in the form of an aqueous solution. If necessary, an alkaline aqueous solution such as sodium hydroxide and buffer solution may be added to the aqueous solution in order to stabilize the radionuclide.
In the case of radionuclide 211At, first, 211At is produced by 209Bi(α,2n)211At nuclear reaction resulting from the irradiation of bismuth with helium particles accelerated to 28 MeV by cyclotron. Next, by heating, the target substance 209Bi is melted and the 211At is vaporized, and the vaporized 211At is collected in a cooling trap, and dissolved in water to prepare an 211At stock solution. If necessary, an alkaline solution such as sodium hydroxide and buffer solution may be added thereto for the purpose of stabilizing 211At.
In the case of radionuclide 210At, first, 210At is produced by 209Bi(α,3n)210At nuclear reaction resulting from the irradiation of bismuth with helium particles accelerated to 29 MeV or more by cyclotron. Next, by the same procedures as above, an aqueous 210At solution is prepared.
In the case of radionuclide 123I, it is available as an aqueous Na123I solution.
In the case of radionuclide 124I, first, 124I is produced by 124Te(p,n)124I nuclear reaction resulting from the irradiation of tellurium with proton particles accelerated by cyclotron. Next, the target substance 124Te is melted, and the 124I is vaporized to prepare an aqueous 124I sodium hydroxide solution.
In the case of radionuclide 125I, it is available as an aqueous Na125I solution.
In the case of radionuclide 131I, it is available as an aqueous Na131I solution.
In the case of radionuclide 76Br, first, 76Br is produced by 76Se(p,n)76Br nuclear reaction resulting from the irradiation of tellurium with proton particles accelerated by cyclotron. Next, the target substance 76Se is melted, and the 76Br is vaporized to prepare an aqueous 76Br sodium hydroxide solution.
In the case of radionuclide 77Br, first, 77Br is produced by 77Se(p,n)77Br nuclear reaction resulting from the irradiation of tellurium with proton particles accelerated by cyclotron. Next, the target substance 77Se is melted, and the 77Br is vaporized to prepare an aqueous 76Br sodium hydroxide solution.
211At has a half-life of 7.2 hours, 210At has a half-life of 8.3 hours, 123I has a half-life of 13.2 hours, and 76Br has a half-life of 16 hours. These radionuclides have a short half-life, and therefore, they should be used in the subsequent reaction immediately after the preparation. On the other hand, 124I has a half-life of 4.2 days, 125I has a half-life of 59.4 days, 131I has a half-life of 8.04 days, and 77Br has a half-life of 57 hours. Although these radionuclides have a relatively long half-life, they are preferably used in the subsequent reaction immediately after the preparation.
Boronic Acid Compound (II) is used usually in a large excess amount relative to the radionuclide, preferably in a concentration of 0.00001 mol/l to 0.5 mol/l, more preferably in a concentration of 0.0001 mol/l to 0.2 mol/l, per 1 Bq to 1,000 GBq of the radionuclide, in terms of reaction efficiency and economic efficiency.
The above reaction is carried out by mixing Boronic Acid Compound (II), the above reagent and the radionuclide, and the mixing order is not particularly limited. The reaction is preferably carried out by adding an aqueous solution of the radionuclide, followed by an aqueous solution of the above reagent to an aqueous solution Boronic Acid Compound (II), or by adding an aqueous solution of the above reagent, followed by an aqueous solution of the radionuclide to an aqueous solution of Boronic Acid Compound (II), more preferably by adding aqueous solution of the radionuclide, followed by an aqueous solution of the above reagent to an aqueous solution of Boronic Acid Compound (II).
The above reaction is carried out in water, i.e., in an organic solvent-free system.
The above reaction is carried out within the range of 0 to 95° C., preferably 10 to 80° C. The reaction time is from 1 minute to 3 hours, preferably from 1 min to 1 hour.
The completion of the reaction is confirmed by the disappearance of the free radionuclide, using thin-layer chromatography (TLC) analysis.
In the production method of the present invention, Radiolabeled Compound (I) can be obtained in a high radiochemical yield of 60% or more, particularly 80% or more, especially 90% or more.
Since the reaction solution after the completion of the reaction contains neither an organic solvent nor a toxic reagent, the reaction solution can be immediately formulated into an injection and the like without isolating Radiolabeled Compound (I).
The reaction of Boronic Acid Compound (II) with a radionuclide is an electrophilic substitution reaction and/or nucleophilic substitution reaction. The introduction site of the radionuclide in Boronic Acid Compound (II) is the benzene ring, which allows the radionuclide to be introduced into the benzene ring well, especially in the case of 211At or 210At.
Radiolabeled Compound (I) may be purified, if necessary, to remove by-products. This purification is preferably carried out by a solid-phase extraction column. As solid-phase extraction columns, those commonly used in the technical field can be used.
Furthermore, after the above purification, ascorbic acid or ascorbate may be added to a final concentration of 0.01% to 10%, preferably 0.1% to 5%. This makes it possible to suppress the decomposition of Radiolabeled Compound (I) and retain it for a long period of time.
Boronic Acid Compound (II) can be produced by the following method comprising Step 2 and Step 3.
wherein
P1 is preferably a diphenylmethyl group.
P2 and P3 are preferably tert-butyl groups.
Preferable examples of the resin for solid phase synthesis in the group derived from the resin for solid phase synthesis for R-L- include Wang resin and the like.
Step 2 is a step of reacting Compound (V) with Compound (IV) to obtain Compound (III). The reaction is carried out by solid phase synthesis.
Compound (V) is produced by a general solid-phase synthesis method commonly used in peptide synthesis, or by a known synthetic method. After production, Compound (V) is subjected to solid-phase synthesis in Step 2 without deresination.
Compound (IV) may be a commercially available product or can be produced according to a method known per se.
The amount of Compound (IV) to be used is generally 1.5 to 4.0 mol, preferably 3.0 mol or more, per 1 mol of Compound (V).
The reaction can be carried out in the presence of a condensing agent, or carried out by converting Compound (IV) to the reactive derivative (e.g., an acid chloride), and then reacting the reactive derivative in the presence of a base.
Examples of the condensing agent include (benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate (PyBOP), (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP), diisopropylcarbodiimide (DIC) and the like. Among them, PyBOP is preferably used.
The amount of the condensing agent to be used is generally 1 mol per 1 mol of Compound (IV).
When the reaction is carried out in the presence of a condensing agent, the reaction may be carried out in the presence of a base. Examples of the base include diisopropylethylamine (DIEA), triethylamine (TEA) and the like. When the condensing agent is PyBOP, DIEA is preferably used.
The amount of the base to be used is generally 1 to 2 mol per 1 mol of Compound (IV).
Examples of the solvent used in the solid-phase synthesis include N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF) and the like.
The solid-phase synthesis is carried out generally at temperature within the range of 0 to 60° C., preferably 10 to 40° C., generally for 1 to 24 hr, preferably 3 to 12 hr.
Thus-obtained Compound (III) is subjected to Step 3 after washing.
Step 3 is a step of subjecting Compound (III) to deprotection and deresination to obtain Boronic Acid Compound (II).
The deprotection and deresination is appropriately selected depending on the type of the protecting group and the resin.
For example, when the carboxy-protecting group (P1, P2, P3, etc.) is a tert-butyl group, a diphenylmethyl group or the like, the carboxy-protecting group of the protected amino acid residue (—CO-A1p-NH—, —CO-A2p-NH—) is a tert-butyl group, and R-L- is a group derived from Wang resin, then Boronic Acid Compound (II) can be obtained by treating Compound (III) under an acidic condition.
The treatment under an acidic condition include treatment with an acid such as trifluoroacetic acid.
After the completion of the reaction, the resin for solid-phase synthesis is removed from the reaction mixture, and the resulting mixture was concentrated to obtain Boronic Acid Compound (II). If necessary, Boronic Acid Compound (II) may be purified by HPLC and the like.
The reaction conditions such as solvent and reaction temperature in each step in the production method of the present invention described above are described in detail as representative examples in Examples below, but are not necessarily limited thereto, and those skilled in the art can make appropriate selections based on their general knowledge in organic synthesis.
Thus-produced Radiolabeled Compound (I) binds specifically to prostate-specific membrane antigen (PSMA), and is subsequently taken up and stably accumulated in cells.
Since Radiolabeled Compound (I) targets cells expressing PSMA, Radiolabeled Compound (I) comprising a therapeutically effective radionuclide may be useful in the treatment of tumors or cancers expressing PSMA. Examples of the therapeutically effective radionuclide include 211At, 210At, 131I, 125I and 77Br.
Furthermore, since Radiolabeled Compound (I) targets cells expressing PSMA, Radiolabeled Compound (I) comprising an imaging effective radionuclide can image tumors or cancers expressing PSMA, and thus may be useful in the diagnosis of the tumors or cancers. Examples of the imaging effective radionuclide include 211At, 131I, 124I, 123I, 77Br and 76Br. Radiolabeled Compound (I) comprising a radionuclide selected from 211At, 131I, 124I, 123I, 77Br and 76Br is used for imaging in positron emission tomography (PET) or single photon emission computed tomography (SPECT).
Moreover, Radiolabeled Compound (I) may treat or diagnose tumors or cancers expressing PSMA with few side effects due to accumulation in the kidneys or salivary glands.
The tumor or cancer expressing PSMA include prostate cancer (including pre-metastatic), especially castration-resistant prostate cancer (CRPC), further especially metastatic castration-resistant prostate cancer (mCRPC).
In addition, since all solid tumors essentially express PSMA in neovascular vessels, Radiolabeled Compound (I) can also be used to treat or image almost all solid tumors, including brain tumors, head and neck cancer, lung cancer, mediastinal tumor, breast cancer, malignant tumors of the liver and biliary tract, pancreatic cancer, malignant tumors of the esophagus and gastrointestinal tract such as the stomach and colon, malignant tumors of the kidneys and adrenal glands, malignant tumor of the urinary tract, bladder cancer, sarcomas, malignant melanoma, uterine and ovarian cancers, malignant tumor of the testis, and bone tumors.
The dose of Radiolabeled Compound (I) used for therapeutic or diagnostic purposes is generally determined by the radionuclide used, the patient's weight, age and sex, therapeutic/diagnostic site, and the like. For example, for human subjects, the estimated effective dosage of Radiolabeled Compound (I) with 211At per dose is approximately 100 MBq to 900 MBq.
Radiolabeled Compound (I) are usually mixed with a pharmaceutically acceptable carrier and used as a pharmaceutical composition. A pharmaceutically acceptable carrier refers to a biocompatible solution with due consideration for sterility, pH, isotonicity, stability, etc, and may include any and all solvents, diluents (including sterile saline, sodium chloride injection, Ringer's solution, dextrose injection, dextrose and sodium chloride injection, lactated Ringer's solution, and other aqueous buffers), dispersants, coatings, antibacterial and antifungal agents, isotonic agents, and the like. Pharmacologically acceptable carriers can also contain stabilizers, preservatives, antioxidants, or other additives known to those skilled in the art.
The dosage form of the pharmaceutical composition is not particularly limited, and it can be prepared as a pharmaceutical composition for oral administration in the form of granules, fine granules, powders, hard capsules, soft capsules, syrups, emulsions, suspensions, liquids and the like; or for parenteral administration such as intravenous administration, intramuscular administration and subcutaneous administration, in the form of injections, drip infusions, transdermal absorptions, transmucosal absorptions, nasal drops, inhalations, suppositories, and the like. These formulations can be prepared according to conventional methods. Preferred are liquid formulations for oral administration or for injection.
Such liquid formulations are prepared by dissolving Radiolabeled Compound (I) in water, but may also be prepared by dissolving Radiolabeled Compound (I) in saline or glucose solution. Buffers or preservatives may be added as necessary. As described above, a reducing agent such as ascorbic acid can also be include. In particular, for the production of injections, the active ingredient is dissolved in distilled water for injection, together with a pH adjuster such as hydrochloric acid, sodium hydroxide, lactose, sodium lactate, sodium monohydrogen phosphate and sodium dihydrogen phosphate, and an isotonic agent such as sodium chloride and glucose, as needed, and then sterilely filtered and filled into an ampule to prepare an injection. Mannitol, dextrin, cyclodextrin, gelatin and the like may also be further added and vacuum lyophilized to prepare an injection that is dissolved immediately before use. Furthermore, lecithin, polysorbate 80, polyoxyethylene hydrogenated castor oil and the like may also be added to the active ingredient and emulsified in water to prepare an emulsion for injection.
The half-life of the radionuclide contained in Radiolabeled Compound (I) is short; it is 7.2 hours for 211At, 8.3 hours for 210At, 8.04 days for 131I, 59.4 days for 125I, 4.2 days for 124I, 13.2 hours for 123I, 57 hours for 77Br, and 16 hours for 76Br. Therefore, it is desirable to prepare the pharmaceutical composition immediately prior to administration to the subject so that it contains the amount of Radiolabeled Compound (I) necessary for administration.
The present invention will be explained in detail by the following Examples, which are merely examples and are not intended to limit the present invention and can be modified without departing from the scope of the present invention.
In the following Examples, the radiochemical yield was calculated using the following formula.
radiochemical yield (%)=(radioactivity of the desired compound on thin-layer plate/total radioactivity on thin-layer plate)×100
The abbreviations are as follows.
Under Ar atmosphere, triphosgene (0.32 g, 1.1 mmol) was dissolved in DCM (80 mL), the solution was cooled to −78° C., and a solution of HCl·H-L-Glu(OtBu)-OtBu (0.80 g, 2.7 mmol) and DIEA (4.6 mL, 27 mmol) in DCM (24 mL) was added dropwise thereto. After 30 min, the mixture was warmed to room temperature, H-L-Lys(Alloc)-Wang resin prepared by deprotecting Fmoc-L-Lys(Alloc)-Wang resin (0.54 mmol) with 20% piperidine/NMP was added thereto, and the mixture was stirred for 1.5 hr. The resin was washed, and to the resin in TCM (10 mL) were added Pd(PPh3)4 (94 mg, 0.08 mmol) and phenylsilane (3.3 mL, 27 mmol), and the mixture was stirred under Ar atmosphere for 1 hr. After the resin was washed, the procedures of condensation with sequential Fmoc-D-Ala(2-Naph)-OH, Fmoc-(4)Ambz-OH, Fmoc-D-Glu(OtBu) and Fmoc-D-Glu(OtBu) by DIC-Oxyma and deprotection with 20% piperidine/NMP were repeated to elongate peptide chain. Then, 0.22 mmol (40%) of the obtained resin was taken, and to the resin in NMP (15 mL) were added 4-(carboxymethyl)phenylboronic acid (0.12 g, 0.68 mmol), PyBOP (0.35 g, 0.68 mmol) and DIEA (0.13 mL, 0.79 mmol), the mixture was stirred for 1.5 hr, and the resin was washed to obtain a protected peptide resin. To the obtained protected peptide resin was added trifluoroacetic acid cocktail (30 mL, TFA/TIS/H2O=95/2.5/2.5), and the mixture was stirred at room temperature for 1 hr to deprotect and deresinate the protected peptide resin. The resin was removed by filtration, the trifluoroacetic acid solution was concentrated, and the crude peptide was solidified with diethyl ether and collected by filtration. Finally, the obtained crude peptide was dissolved in 30% aqueous DMSO solution, and purified by reverse-phase HPLC. The fraction containing the target product was lyophilized to obtain Compound 1 as a lyophilized powder (yield: 54 mg, purity 99% or more (HPLC method), molecular weight: observed value 1070.4[M+H]+, 1052.4[M−H2O+H]+, theoretical value 1070.4[M+H]).
Compound 2 was synthesized by the same process as in Example 1, except that Fmoc-D-Ala(2-Naph)-OH and Fmoc-D-Glu(OtBu) were changed to Fmoc-L-Ala(2-Naph)-OH and Fmoc-L-Glu(OtBu) (yield: 204 mg, purity 99% or more (HPLC method), molecular weight: observed value 1070.3[M+H]+, 1052.4[M−H2O+H]+, theoretical value 1070.4[M+H]).
The powder of Compound 1 obtained in Example 1 was dissolved in 7% aqueous sodium hydrogencarbonate solution to 0.1 mg/mL. To the solution (10 μL) were added 211At aqueous solution (20 μL, 20 MBq) and 0.1 mol/L aqueous potassium iodide solution (30 μL), and the reaction was carried out at 80° C. for 1 hr. The reaction solution was injected into a solid-phase extraction cartridge (Oasis HLB, Waters), the cartridge was washed with water (1 mL), and 30% aqueous ethanol solution (0.5 mL) was injected into the cartridge to collect the eluate. The above reaction solution and eluate were analyzed by thin-layer chromatograph method (TLC). Silica gel 60 (Merck) was used as a thin plate and developed with acetonitrile/water mixture (2/1). The radioactivity on the thin plate after development was exposed to an imaging plate (GE Healthcare) and analyzed by a bioimaging analyzer (BAS7000, GE Healthcare). The results were shown in
The powder of Compound 2 obtained in Example 2 was dissolved in 7% aqueous sodium hydrogencarbonate solution to 0.1 mg/mL. To the solution (10 μL) were added 211At aqueous solution (20 μL, 20 MBq) and 0.1 mol/L aqueous potassium iodide solution (30 μL), and the reaction was carried out at 80° C. for 1 hr. The reaction solution was injected into a solid-phase extraction cartridge (Oasis HLB, Waters), the cartridge was washed with water (1 mL), and 30% aqueous ethanol solution (0.5 mL) was injected into the cartridge to collect the eluate. The above reaction solution and eluate were analyzed by thin-layer chromatograph method (TLC). Silica gel 60 (Merck) was used as a thin plate and developed with acetonitrile/water mixture (2/1). The radioactivity on the thin plate after development was exposed to an imaging plate (GE Healthcare) and analyzed by a bioimaging analyzer (BAS7000, GE Healthcare). The results were shown in
HCl-Fmoc-L-Lys-ODpm (2.5 g, 4.4 mmol) was dissolved in DMF (20 mL), succinic anhydride (0.48 g, 4.8 mmol) and DIEA (0.82 mL, 4.8 mmol) were added thereto, and the mixture was stirred at room temperature for 1.5 hr. To the reaction solution was added ethyl acetate, and the mixture was washed with 0.2 N hydrochloric acid water and brine, and dried over magnesium sulfate, and the solvent was evaporated under reduced pressure to give Fmoc-L-Lys(Suc)-ODpm (2.1 g, 89%).
Under Ar atmosphere, triphosgene (0.42 g, 1.4 mmol) was dissolved in dichloromethane (90 mL), the mixture was cooled to −78° C., and a solution of HCl-H-L-Glu(OtBu)-OtBu (1.0 g, 3.5 mmol) and DIEA (6.0 mL, 35 mmol) in dichloromethane (30 mL) was added dropwise thereto. After 30 min, the mixture was warmed to room temperature, H-L-Lys(Alloc)-Wang resin prepared by deprotecting Fmoc-L-Lys(Alloc)-Wang resin (0.7 mmol) with 20% piperidine/NMP was added thereto, and the mixture was stirred for 2 hr. The resin was washed, and to the resin in chloroform (10 mL) were added Pd(PPh3)4 (0.12 g, 0.11 mmol) and phenylsilane (4.3 mL, 35 mmol), and the mixture was stirred under Ar atmosphere for 1 hr. After the resin was washed, the procedures of condensation with sequential Fmoc-D-Ala(2-Naph)-OH, Fmoc-(4)Ambz-OH, Fmoc-L-Lys(Suc)-ODpm (obtained Reference Example 1) and Fmoc-Gly-OH by DIC-Oxyma and deprotection with 20% piperidine/NMP were repeated to elongate peptide chain. Then, to the resin in NMP (15 mL) were added 4-(carboxymethyl)phenylboronic acid pinacol ester (0.55 g, 2.1 mmol), PyBOP (1.1 g, 2.1 mmol) and DIEA (0.42 mL, 2.5 mmol), the mixture was stirred for 1 hr, and the resin was washed to obtain a protected peptide resin. To the obtained protected peptide resin was added trifluoroacetic acid cocktail (60 mL, TFA/TIS/H2O=95/2.5/2.5), and the mixture was stirred at room temperature for 1 hr to deprotect and deresinate the protected peptide resin. The resin was removed by filtration, the solvent of the filtrate was evaporated under reduced pressure, and the residue was solidified and washed with diethyl ether. The obtained solid was dissolved in 50% aqueous acetic acid (10 mL), and the solution was stirred at room temperature for 40 min, and purified by reverse-phase HPLC. The fraction containing the target product was lyophilized to give Compound as a lyophilized powder (yield 0.20 g, yield 26%, purity 98% or more (HPLC method), molecular weight: observed value 1097.5[M+H]+, 1079.5[M−H2O+H]+, theoretical value 1097.5[M+H]).
Compound 6 was synthesized by the same process as in Example 5, except that the peptide chain to be elongated was changed from Fmoc-D-Ala (2-Naph)-OH, Fmoc-(4)Ambz-OH, Fmoc-L-Lys(Suc)-ODpm and Fmoc-Gly-OH to Fmoc-D-Ala(2-Naph)-OH, Fmoc-(4)Ambz-OH, Fmoc-D-Glu(OtBu)—OH, Fmoc-D-Glu(OtBu)—OH, Fmoc-L-Lys(Suc)-ODpm and Fmoc-Gly-OH (yield 0.28 g, yield 29%, purity 98% or more (HPLC method), molecular weight: observed value 1353.5[M−H]−, 1335.5[M−H2O−H]− theoretical value 1353.5[M−H])
Example 7 Production of Compound 7 The powder of Compound 5 obtained in Example 5 was dissolved in 7% aqueous sodium hydrogencarbonate solution to 0.1 mg/mL. To the solution (20 μL) were added 7% aqueous sodium hydrogencarbonate solution (50 μL), 211At aqueous solution (16 μL, 38.5 MBq) and 0.1 mol/L aqueous potassium iodide solution (40 μL), and the reaction was carried out at 80° C. for 45 min. The reaction solution was injected into a solid-phase extraction cartridge (Oasis HLB, Waters), the cartridge was washed with water (1 mL), and 20% ethanol aqueous solution (0.5 mL) and 30% ethanol aqueous solution were injected successively into the cartridge to collect the eluate. The above reaction solution and 30% ethanol eluate were analyzed by thin-layer chromatograph method (TLC). Silica gel 60 (Merck) was used as a thin plate and developed with acetonitrile/water mixture (2/1). The radioactivity on the thin plate after development was exposed to an imaging plate (GE Healthcare) and analyzed by a bioimaging analyzer (BAS7000, GE Healthcare). The results were shown in
The powder of Compound 6 obtained in Example 6 was dissolved in 7% aqueous sodium hydrogencarbonate solution to 0.1 mg/mL. To the solution (20 μL) were added 7% aqueous sodium hydrogencarbonate solution (40 μL), 211At aqueous solution (22 μL, 20 MBq) and 0.1 mol/L aqueous potassium iodide solution (40 μL), and the reaction was carried out at 80° C. for 45 min. The reaction solution was injected into a solid-phase extraction cartridge (Oasis HLB, Waters), the cartridge was washed with water (1 mL), and 20% ethanol aqueous solution (0.5 mL) was injected into the cartridge to collect the eluate. The above reaction solution and eluate were analyzed by thin-layer chromatograph method (TLC). Silica gel 60 (Merck) was used as a thin plate and developed with acetonitrile/water mixture (2/1). The radioactivity on the thin plate after development was exposed to an imaging plate (GE Healthcare) and analyzed by a bioimaging analyzer (BAS7000, GE Healthcare). The results were shown in
SCID mice (9 weeks old, male, n=5) were subcutaneously transplanted with human prostate cancer cells (LNCaP, 0.5×107 cells/mouse), and then kept for one month. The mice were divided into Compound 3 administration group (n=3) and control group (n=2). For the Compound 3 administration group, Compound 3 (0.43±0.01 MBq) was administered via the tail vein. For the control group, physiological saline was administered. The mice in the Compound 3 administration group (n=3) were anesthetized with isoflurane inhalation at 3 and 24 hours after administration, and the planar images were taken using a SPECT camera (E-cam, Siemens) (matrix size: 256×256, pixel size 1.2×1.2 mm, collimator: LEAP, energy window: 79 keV±20%, image acquisition time 10 min or 20 min). The results were shown in
The mice in the Compound 3 administration group (0.5 MBq, n=3) and control group (CTL, n=2) of Experimental Example 1 were kept for 3 weeks thereafter, and changes in tumor size were measured. The tumor size was standardized by size at the time of drug administration, and the relative ratio (fold change) to subsequent tumor size was calculated. The results were shown in
The above results showed that Compound 3 is useful as a therapeutic agent for prostate cancer.
SCID mice (9 weeks old, male, n=5) were subcutaneously transplanted with human prostate cancer cells (LNCaP, 0.5×107 cells/mouse), and then kept for one month. Compound 3, 4, 7 or 8 (approximately 0.1 MBq) was administered to the tumor-transplanted mice or normal mice, and the mice were dissection under isoflurane inhalation anesthesia at 3 and 24 hours after administration to collect various organs including blood, urine and tumors. The radioactivity distribution (% ID) and radioactivity distribution per 1 g of organ weight (% ID/g) were measured for each organ. The results were shown in
SCID mice (9 weeks old, male, n=5) were subcutaneously transplanted with human prostate cancer cells (LNCaP, 0.5×107 cells/mouse), and then kept for one month. The tumor-transplanted mice were divided into Compound 3, 7 or 8 administration group (0.4 MBq or 1 MBq, n=3) and control group (CTL, n=2 or 3), and kept for 3 weeks thereafter, and changes in tumor size and body weight were measured. The results were shown in
According to the present invention, a radiolabeled compound that binds specifically to PSMA, is effective in the treatment and diagnosis of tumors or cancers expressing PSMA, for example, the treatment and diagnosis of prostate cancer, especially castration-resistant prostate cancer (CRPC), further especially metastatic castration-resistant prostate cancer (mCRPC), and does not exhibit side effects due to accumulation in the kidney or salivary glands, can be provided.
This application is based on patent application No. 2021-125774 filed on Jul. 30, 2021 in Japan, the contents of which are encompassed in full herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-125774 | Jul 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/029283 | 7/29/2022 | WO |
