Auger electron radiotherapy

Abstract

This invention provides an Auger electron radiotherapy drug that can selectively and effectively release a sufficient amount of Auger electrons into the nuclear DNA of cancer cells, even in small amounts, thereby reducing or killing cancer cells. The Auger electron radioactive isotope has a half-life that is not too short but not too long, making it highly safe and readily available. [Solution] The Auger electron radioactive therapeutic agent is encapsulated in a stimulus-responsive liposome that accumulates in cancer tissue and / or cancer cells, such that an anthracycline derivative is released upon stimulation, in which an Auger electron-emitting radioisotope-substituted benzene ring-containing group or radioisotope-substituted alkyl group is covalently bonded to the keto or amino group of anthracyclines selected from doxorubicin or daunorubicin and their reduced forms or alkoxy group-substituted forms thereof, is a stimulus-responsive liposome, or is bound to an antibody, oligopeptide, or antigen that accumulates in cancer tissue and / or cancer cells via a stimulus-responsive linker.

Description

Technical Field

[0001] The present invention relates to an Auger electron radiotherapy drug that accumulates in cancer tissue and emits Auger electrons into the nucleus of cancer cells to reduce or kill cancer cells.

Background Art

[0002] As the three major cancer treatment methods, there are surgical treatment for surgically removing cancer tissues such as the primary cancer focus or metastatic lesions or organs deteriorated by tumors, drug therapies such as chemotherapy, endocrine therapy (hormone therapy), and molecular targeted therapy using anti-cancer drugs, and radiotherapy for irradiating cancer tissues with therapeutic radiation such as X-rays, electron beams, proton beams, heavy particle beams, α-rays, β-rays, γ-rays, and neutron beams to reduce or kill cancer cells. Recently, nuclear medicine treatment has also been carried out, in which a radioactive isotope is accumulated in cancer tissues such as the primary cancer focus, especially in cancer cells, and only the surrounding area is affected by radiation to reduce or kill cancer cells.

[0003] Such nuclear medicine treatment is to administer a probe therapeutic drug compound labeled with a radioactive isotope nuclide that emits α-rays or β - rays with high cytotoxicity, and reduce or kill cancer cells by shrinking cancer tissues such as the primary cancer focus. A cancer target affinity group that binds to a cancer target receptor such as a protein produced from cancer cells in a cancer tissue such as the primary cancer focus and a radioactive nuclide that emits α-rays or β - rays are administered to accumulate in cancer tissues such as the primary cancer focus, and the short-range α-rays or β - rays are selectively irradiated from the body to cancer cells to selectively reduce or kill cancer cells as much as possible and obtain an anti-cancer effect.

[0004] Such alpha rays have a high linear energy transfer (LET) of 80 - 100 keV / μm, but their range is about 10 - 30 μm, which is 10 - 100 μm for several cells. Therefore, they will cause some damage to normal cells. On the other hand, beta rays not only have a relatively low LET of 0.1 - 1.0 keV / μm, but also have a long range of 0.1 - 10 mm. Therefore, normal cell damage is a concern and it cannot be said to be cancer cell specific.

[0005] Therefore, in recent years, as described in Non-Patent Document 1, nuclear medicine treatment using Auger electrons as radiation has been under development. Auger electrons have a relatively high linear energy transfer with a LET of 4 - 26 keV / μm, while their range is extremely short at 2 - 500 nm (0.5 μm). Since the diameter of the cell nucleus itself is 5 - 8 μm, if they can accumulate in cancer cells, especially in the nucleus, direct Auger electron irradiation of the DNA in the nucleus of cancer cells becomes possible, and thus they have attracted attention.

[0006] However, there are few known effective Auger electron radiopharmaceuticals that selectively emit Auger electrons to the DNA in cancer tissues, especially in the nucleus of cancer cells, to reduce or kill cancer cells. The development of such therapeutic agents has been desired.

Prior Art Documents

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention was made to solve the aforementioned problems, and aims to provide an Auger electron radiotherapy drug that can selectively and effectively release a sufficient amount of Auger electrons into the nuclear DNA of cancer cells, even in small amounts, thereby reducing or killing cancer cells, and which has an Auger electron radioactive isotope half-life that is not too short but not too long, is highly safe, and can be supplied stably. [Means for solving the problem]

[0009] The Auger electron radiotherapy drugs developed to achieve the aforementioned objectives are Anthracycline derivatives, selected from doxorubicin or daunorubicin and their reduced forms from the keto group to the hydroxyl group, or their alkoxy group-substituted forms with 2-6 carbon atoms from the methoxy group, have an Auger electron-emitting radioisotope-substituted benzene ring-containing group or radioisotope-substituted alkyl group covalently bonded to the keto, amino, or hydroxyl group of anthracyclines, They are encapsulated in stimulus-responsive liposomes that accumulate in cancer tissue and / or its cancer cells so as to be released upon stimulation, or It is bound to antibodies, oligopeptides, or antigens that accumulate in cancer tissue and / or cancer cells via a stimulus-responsive linker, so as to be cleaved and released upon stimulation. It is characterized by being such.

[0010] This Auger electron radioactive therapeutic agent contains, for example, a radioisotope-substituted benzene ring-containing group or a radioisotope-substituted alkyl group that contains the radioisotope 125 I or 77 It will be designated as Br.

[0011] This Auger electron radioactive therapeutic agent may accumulate in the cancer tissue and / or its cancer cells and / or nuclei, using the liposomes, antibodies, oligopeptides, or antigens, and may release Auger electrons from the radioactive isotope through spontaneous decay.

[0012] This Auger electron radioactive therapeutic agent is an alkyl group in which the substituted benzene ring-containing group may, for example, have a hydroxyl group on the benzene ring, or The radioactive isotope-substituted alkyl group may have a hydroxyl group, a halogen group, a nitro group, or a cyano group, and is a linear, branched, and / or cyclic alkyl group. That is the case.

[0013] The Auger electron radioactive therapeutic agent may have the substituted benzene ring-containing group or the radioisotope-substituted alkyl group bonded by any of the aforementioned covalent bonds selected from substitution, addition, and dehydration.

[0014] This Auger electron radiotherapy drug is characterized in that the stimulus is at least one of the following selected from, for example, a reducing state, an acidic pH state, an enzyme activity state, a heating stimulus, a light stimulus, and an ultrasonic stimulus at the target site.

[0015] This Auger electron radiotherapy drug is characterized in which the anthracycline derivative is bound to the antibody, and the antibody is internalized within cancer cells, and is an anti-HER2 antibody, an anti-EGFR antibody, or an anti-PD-L1 antibody.

[0016] This Auger electron radiotherapy drug is characterized in that the anthracycline derivative is bound to the oligopeptide, and the oligopeptide is, for example, an RGD sequence-containing peptide, or the antigen is prostate-specific membrane antigen (PSMA).

[0017] This Auger electron radioactive therapeutic agent is characterized in which the anthracycline derivative is conjugated to the antibody, oligopeptide, or antigen via the stimulus-responsive linker, and the stimulus-responsive linker is, for example, The following chemical formula (1) [ka] A reduction-responsive linker represented by Chemical formula (2) [ka] A pH-responsive linker represented by It is cleaved by enzymatic activity of cathepsin B or β-glucuronidase, as shown in the following chemical formulas (3-1) to (3-3). [ka] [ka] [ka] An enzyme activity-responsive linker represented by one of the following groups It is one of the following.

[0018] The Auger electron radioactive therapeutic agent is one in which the anthracycline derivative is encapsulated in the stimulus-responsive liposome, for example, the stimulus-responsive liposome is formed of at least 1,2-dihexadecanoyl-sn-glycero-3-phosphocholine, poly(N-isopropylacrylamide)-modified phosphoethanolamine, and / or dioleoylphosphoethanolamine, or further contains IR780 and / or perfluorocarbon.

[0019] In this Auger electron radioactive therapeutic agent, it is preferable that the stimulus-responsive liposomes are responsive to one of the following stimuli: heating, light, or ultrasound.

[0020] This Auger electron radiotherapy drug contains the anthracyclines described above, as shown in the following chemical formula (4-1) [ka] Doxorubicin, as shown by the following chemical formula (4-2) [ka] The reduced form of doxorubicin from the keto group to the hydroxyl group shown by (4-3), or a diastereomer of only one of them, or the following chemical formula (4-3) [ka] The daunorubicin shown in, or the following chemical formula (4-4) [ka] The reduced form of daunorubicin from the keto group to the hydroxyl group, or a diastereomer of only one of these, as shown above. It is preferable that this be the case.

[0021] The anticancer drug developed to solve the aforementioned problems is one that contains the Auger electron radiotherapy drug and is administered orally or intravenously. [Brief explanation of the drawing]

[0022] [Figure 1] The Auger electron radioactive therapeutic agent to which the present invention is applied contains an anthracycline derivative having a radioisotope-substituted benzene ring-containing group encapsulated in a stimulus-responsive liposome, and this figure schematically illustrates its effects. [Figure 2] This figure shows liquid chromatogram charts for Auger electron radiotherapy drugs to which the present invention is applied and Auger electron radiotherapy drugs to which the present invention is not applied. [Figure 3] This graph shows the cell uptake performance of the Auger electron radiotherapy drug to which the present invention applies, both on the cell surface and inside the cell. [Figure 4] This graph shows the uptake performance into the cell nucleus of Auger electron radiotherapy drugs to which the present invention is applied. [Figure 5] This graph shows the cancer cell damage performance at different concentrations of Auger electron radiotherapy drugs to which the present invention is applied. [Figure 6] This figure shows liquid chromatogram charts for another Auger electron radiotherapy to which the present invention is applied and for an Auger electron radiotherapy to which the present invention is not applied. [Figure 7] This figure shows liquid chromatogram charts for another Auger electron radiotherapy to which the present invention is applied and for an Auger electron radiotherapy to which the present invention is not applied. [Figure 8] This graph shows the cell and nucleus uptake performance of another Auger electron radiotherapy drug to which the present invention is applied. [Figure 9] This graph shows the cancer cell damaging performance at different concentrations of another Auger electron radiotherapy drug to which the present invention is applied. [Figure 10] This graph shows the kinetic effects of another Auger electron radiotherapy drug to which the present invention is applied, under heated / unheated conditions on cancer tissue. [Figure 11] This figure shows liquid chromatogram charts for another Auger electron radiotherapy to which the present invention is applied and for an Auger electron radiotherapy to which the present invention is not applied. [Figure 12] This graph shows the cell and nucleus uptake performance of another Auger electron radiotherapy drug to which the present invention is applied. [Modes for carrying out the invention]

[0023] The following describes in detail embodiments for carrying out the present invention, but the scope of the present invention is not limited to these embodiments.

[0024] The Auger electron radioactive therapeutic agent of the present invention is an anthracycline derivative in which doxorubicin or daunorubicin or its derivative anthracyclines are covalently bonded to an Auger electron-emitting radioisotope-substituted benzene ring-containing group, and is encapsulated in a stimulus-responsive liposome that accumulates in cancer tissue so as to be released upon stimulation, or is bound to an antibody, oligopeptide, or antigen that accumulates in cancer tissue via a stimulus-responsive linker so as to be cleaved and released upon stimulation.

[0025] First, I will explain the preferred first embodiment of Auger electron radiotherapy. The Auger electron radioactive therapeutic agent of the present invention is the chemical formula (4-1) [ka] This invention relates to an anthracycline derivative, represented by doxorubicin, in which an Auger electron-emitting radioisotope-substituted benzene ring-containing group is N-substituted to the amino group of anthracyclines. This anthracycline derivative is bound to an oligopeptide that accumulates in cancer tissue, particularly an RGD (arginine-glycine-aspartic acid) sequence-containing peptide or an antigen that accumulates in cancer tissue, via a stimulus-responsive linker, so that it is cleaved and released upon stimulation.

[0026] This Auger electron radioactive therapeutic agent accumulates in cancer tissue, particularly cancer cells, from the bloodstream due to an RGD-containing peptide that accumulates in cancer tissue. Subsequently, due to its unique property of intercalating doxorubicin into DNA upon stimulation, a radioisotope-substituted benzene ring-containing group-bonded anthracycline derivative is released, accumulating in the nucleus of cancer cells and exerting its anticancer effect.

[0027] Doxorubicin is an anticancer drug (antineoplastic agent) that is effective against malignant lymphoma (reticulosarcoma, lymphoma, Hodgkin's disease), lung cancer, gastrointestinal cancers (stomach cancer, gallbladder and bile duct cancer, pancreatic cancer, liver cancer, colorectal cancer, etc.), breast cancer, bladder cancer, osteosarcoma, and others. When doxorubicin is administered to patients with these cancers, it exerts its anticancer effect by forming a complex with the DNA of cancer cells, thereby inhibiting DNA polymerase and RNA polymerase reactions and suppressing the biosynthesis of both DNA and RNA. Similarly, Auger electron radioactive therapies exert their anticancer effect. On the other hand, Auger electron-emitting radioactive isotopes enter the nucleus of cancer cells and release Auger electrons, causing DNA damage without adversely affecting surrounding normal cells, thereby reducing or killing cancer cells through apoptosis. Similarly, Auger electron radioactive therapies exert their anticancer effect. When Auger electron radiotherapy is administered to these cancer patients, the synergistic effect of doxorubicin's anticancer action and the nuclear DNA damage caused by Auger electrons results in a high reduction or death of cancer cells. Therefore, Auger electron radiotherapy can be an excellent anticancer agent.

[0028] Among such Auger electron radiotherapeutic drugs, the Auger electron-emitting radioisotopes have a half-life of 59.4 days. 125 I. Half-life of 57.0 hours 77 Br is one example. Among them, it has a short half-life and is highly safe. 77 Br is preferred. The Auger electron-emitting radioactive isotopes in anthracycline derivatives that are cleaved from Auger electron radiopharmaceuticals and accumulated in the nucleus release Auger electrons when they transition from the excited state to the ground state through spontaneous decay.

[0029] The Auger electron-emitting radioisotope is directly substitutionally bonded to the benzene ring of the benzene ring-containing group. Examples of the benzene ring-containing group include an aralkyl group or an alkyl group which may have one or more substituents such as a hydroxy group. Examples of the aralkyl group include a phenylalkyl group, more specifically a benzyl group or a phenethyl group. Examples of the alkyl group include a linear, branched, and / or cyclic alkyl group having 1 to 6 carbon atoms, more specifically a neopentyl group. The Auger electron-emitting radioisotope may be substituted at any of the 2-6 positions of the benzene ring of the benzene ring-containing group, or may be substituted at any position of the alkyl group.

[0030] Such a radioisotope-substituted benzene ring-containing group is bonded to doxorubicin, which is an anthracycline, by a covalent bond such as a substitutional bond, an addition bond, or a dehydration bond. Specifically, the radioisotope-substituted benzene ring-containing group is N-substitutionally bonded to the amino group of the 3-amino-2,3,6-trideoxy-hexopyranose ring of doxorubicin.

[0031] The oligopeptide having an accumulation property in cancer tissue is preferably an RGD sequence-containing peptide, and more preferably a cyclic RGD sequence-containing peptide. α v β3 integrin is expressed in the endothelial cells of blood vessels during the promotion of angiogenesis by tumors, or α v β3 integrin is expressed in the cancer cells of the primary cancer foci of tumors. The RGD sequence-containing peptide shows high affinity for α v β3 integrin. Examples of the cyclic RGD sequence-containing peptide include those having an arginine-glycine-aspartic acid-amino acid sequence. More specifically, cyclic (arginine-glycine-aspartic acid-phenylalanine-cysteine), cyclic (arginine-glycine-aspartic acid-tyrosine-cysteine), cyclic (arginine-glycine-aspartic acid-phenylalanine-lysine) oligopeptide derivatives, and cyclic (arginine-glycine-aspartic acid-tyrosine-lysine) oligopeptide derivatives can be mentioned.

[0032] Antigens that accumulate in cancer tissue include prostate-specific membrane antigens. Prostate-specific membrane antigens are proteins strongly expressed on the surface of prostate cancer cells and are type II membrane glycoproteins that possess folate hydrolysis activity and neuropeptidase activity.

[0033] The triggering stimuli that cause anthracycline derivatives to cleave from a stimulus-responsive linker bound to an oligopeptide that accumulates in cancer tissue and be released into the cell nucleus are a reducing state in the cancer tissue and / or cancer cells at the treatment site, an acidic pH state, the enzymatic activity state of the cancer cells, and at least one of the following stimuli selected from heating, light, and ultrasound.

[0034] In cancer tissue, a reducing state acts as a trigger. This reduces-responsive linker, bound to oligopeptides such as cyclic RGD sequence-containing peptides that have affinity for cancer tissue, is cleaved and broken at its binding site to anthracycline derivatives when reducing substances such as glutathione are present at high concentrations in the cancer tissue and / or within the cancer cells, thereby releasing the anthracycline derivative.

[0035] A reduction-responsive linker that cleaves and releases anthracycline derivatives in response to a reducing state in cancer tissue and / or its cancer cells is, for example, [ka] (In formula (1), -SS- is not limited to any group that can bind to an oligopeptide, such as an RGD sequence-containing peptide, preferably a cyclic RGD sequence-containing peptide, and the terminal -S- may be derived from cysteine ​​in the oligopeptide.) To explain using the example of a reduction-responsive linker being the group represented by chemical formula (1), the -SS-, which is the binding site to the RGD sequence-containing peptide, is reduced and specifically cleaved into -SH, and this -SH group attacks the ester group of the same chemical formula (1), resulting in mercaptoethanol and subsequent splitting. As a result, the anthracycline derivative is released along with the Auger electron-emitting radioisotope-substituted benzene ring-containing group, and the Auger electron-emitting radioisotope in the anthracycline derivative, which has been cleaved from the Auger electron radioactive therapeutic agent and accumulated in the nucleus, releases Auger electrons when it transitions from the excited state to the ground state.

[0036] Furthermore, the acidic pH state of the cancerous tissue and / or cancer cells, which are the target sites for treatment, acts as a trigger for the release of anthracycline derivatives. These are caused by pH-responsive linkers bound to antibodies taken up by cancer tissue through endocytosis, or by pH-responsive linkers bound to oligopeptides such as highly aggregated RGD sequence-containing peptides that have affinity for cancer tissue. These linkers are cleaved at their binding sites to anthracycline derivatives by endosomes and lysosomes with low pH, thereby releasing the anthracycline derivatives.

[0037] pH-responsive linkers that cleave and release anthracycline derivatives in response to the acidic pH state of cancer tissue and / or its cancer cells are, for example, [ka] This is a group represented by formula (2-1). In formula (2-1), -S- is not limited to any group that can bind to an oligopeptide, such as an anthracycline derivative, and may be derived from cysteine ​​in the oligopeptide. -NH-N= is not limited to any group that can bind to an anthracycline derivative, and may be imino-bonded to the keto group of the hydroxyacetyl group of doxorubicin, which is an anthracycline derivative. To explain using the example of a group represented by pH-responsive linker chemical formula (2-1), it is a trigger that is cleaved in a pH-specific manner at the binding site with the anthracycline derivative, such as the =NH- group, and releases the anthracycline derivative. More specifically, the imino group that is dehydrated and bonded to the keto group of the hydroxyacetyl group of doxorubicin is hydrolyzed by acidic conditions in endosomes and liposomes, and the anthracycline derivative is released along with the Auger electron-emitting radioisotope-substituted benzene ring-containing group.

[0038] Furthermore, the stimulus of the enzymatic activity state of the cancerous tissue and / or its cancer cells, which are the target sites for treatment, acts as a trigger for the release of anthracycline derivatives. This is achieved by the enzymatic activity of enzymes such as cathepsin B and β-glucuronidase present in the tissue and / or its cancer cells, which cleave and break the binding site with the anthracycline derivative.

[0039] Reduction-responsive linkers that cleave and release anthracycline derivatives in response to the enzymatic activity state of cancer tissue and / or its cancer cells are, for example, cleaved by the enzymatic activity of cathepsin B, which is overexpressed in cancer tissue and / or cancer cells and is involved in tumor progression, and β-glucuronidase, whose activity is enhanced in the tumor microenvironment. The following chemical formulas (3-1) to (3-3) [ka] [ka] [ka] This is the group represented by (3-1). To explain using the example where the enzyme activity-responsive linker is the group represented by chemical formula (3-1), cathepsin B, which is overexpressed in cancer tissue and / or cancer cells, the site of treatment, selectively cleaves the amide bond between the citrulline of chemical formula (3-1) in the Auger electron-radioactive therapeutic agent accumulated therein and the p-aminobenzyloxycarbonyl linker. The p-aminobenzyloxycarbonyl linker then self-cleaves, releasing the anthracycline derivative along with the Auger electron-emitting radioisotope-substituted benzene ring-containing group. The Auger electron-emitting radioisotope in the anthracycline derivative accumulated in the nucleus then releases Auger electrons when the atom transitions from the excited state to the ground state through spontaneous decay. The same applies when the group represented by chemical formulas (3-2) and (3-3) is used instead of the group represented by chemical formula (3-1).

[0040] A more preferred embodiment of an Auger electron radioactive therapeutic agent is one in which an anthracycline derivative, in which an Auger electron-emitting radioisotope-substituted benzene ring-containing group is covalently bonded to the amino group of an anthracycline such as doxorubicin, is bonded to an oligopeptide containing an RGD sequence via a pH-responsive linker, specifically the following chemical formula (5): [ka] It is represented by [this].

[0041] The Auger electron radioactive therapeutic agent represented by chemical formula (5) is first prepared by introducing tributyltin into a benzyl halide by a reductive amination reaction, then 2-pyridine-2-yldisulfaneyl ethyl carbonate, and after attaching a cyclic RGD sequence-containing peptide, a tin-iodine exchange reaction is performed. 125 This is obtained by labeling with 1. This Auger electron radioactive therapeutic agent can be administered to a living organism with cancerous tissue by an appropriate administration method such as intravenous injection, and by accumulating in the cancerous tissue, Auger electrons can be released.

[0042] Next, a preferred second embodiment of the Auger electron radiotherapy drug will be described. As Auger electron radioactive therapeutics, we have shown examples where anthracycline derivatives, in which an Auger electron-emitting radioisotope-substituted benzene ring-containing group is covalently bonded to anthracyclines, are bound to oligopeptides via a stimulus-responsive linker. However, instead of oligopeptides, they may also be bound to antibodies.

[0043] Such antibodies include anti-HER2 antibodies, anti-EGFR antibodies, and anti-PD-L1 antibodies. These antibodies are monoclonal antibodies against the cell surface proteins of cancer tissue and its cancer cells, which are the target sites for treatment, and are required to be internalized within the cancer cells. Anti-HER2 antibodies are antibodies against the human epidermal growth factor receptor (HER2), which is involved in the proliferation of cancer cells; anti-EGFR antibodies are antibodies that bind to the epidermal growth factor receptor (EGFR) on the cancer cell membrane and inhibit the function of epidermal growth factor (EGF); and anti-PD-L1 antibodies are antibodies that inhibit PD-L1, which is expressed on immune cells and cancer cells, and are molecular targeted drugs, also known as immune checkpoint inhibitors. In addition to the high specificity of binding of these antibodies, the EPR effect (Enhanced Permeability and Retention effect) allows Auger electron radioactive therapeutics to accumulate in cancer tissue. The mode of binding between the antibody via the stimulus-responsive linker and the anthracycline derivative having an Auger electron-emitting radioisotope-substituted benzene ring-containing group is the same as described above, so a redundant explanation will be omitted.

[0044] A more preferred embodiment of an Auger electron-radioactive therapeutic agent is one in which an anthracycline derivative, in which an Auger electron-emitting radioisotope-substituted benzene ring-containing group is covalently bonded to the amino group of an anthracycline such as doxorubicin, is conjugated to an antibody via a pH-responsive linker, which is a stimulus-responsive linker, specifically the following chemical formula (6): [ka] (In formula (6), -S- is not limited to any substance that can bind to the antibody, and may be derived from cysteine ​​in the antibody. The roughly Y-shaped portion is a schematic representation of an antibody having two H chains and two L chains.) These are some examples.

[0045] Auger electron radiotherapy drugs represented by chemical formula (6) 125 This Auger electron radiotherapy drug is obtained by preparing a benzyl halide into which a radioactive isotope such as I has been introduced, reacting it with 6-maleimidocaproic acid hydrazide, and then performing a maleimido-thiol reaction. This Auger electron radiotherapy drug can be administered to a living organism with cancerous tissue by appropriate administration methods such as intravenous injection or oral administration, and by accumulating in the cancerous tissue, Auger electrons can be released.

[0046] Next, a preferred third embodiment of the Auger electron radiotherapy drug will be described. As Auger electron-emitting therapeutic agents, these anthracycline derivatives, in which an Auger electron-emitting radioisotope-substituted benzene ring-containing group is covalently bonded to anthracyclines, may be encapsulated in stimulus-responsive liposomes that accumulate in cancer tissue and / or cancer cells so as to be released upon stimulation. The bonding mode of the anthracycline derivative having the Auger electron-emitting radioisotope-substituted benzene ring-containing group is the same as described above, so a redundant explanation will be omitted.

[0047] Such stimulus-responsive liposomes are formed as a main component of at least 1,2-dihexadecanoyl-sn-glycero-3-phosphocholine (DPPC), poly(N-isopropylacrylamide)-modified phosphoethanolamine, and / or dioleoylphosphoethanolamine, or further contain 2-[2-[2-chloro-3-[2-(3,3-dimethyl-1-propylindoline-2-ylidene)ethylidene]cyclohexa-1-en-1-yl]vinyl]-3,3-dimethyl-1-propyl-3H-indole-1-ium (IR780), and / or perfluorocarbon, and may have cholesterol, 1,2-distearoyl-sn-glycerol-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000], and / or 1,2-distearoyl-sn-glycero-3-phosphocholine. Among stimulus-responsive liposomes, temperature-responsive liposomes include those that primarily use DPPC or poly(N-isopropylacrylamide)-modified phosphoethanolamine as liposome components, photoresponsive liposomes include those that contain dioleoylphosphoethanolamine as a liposome component while also containing IR780 as a light-responsive component, and ultrasound-responsive liposomes include those containing perfluorocarbons. Stimulus-responsive liposomes accumulate in cancer tissue and around cancer cells upon heating, light irradiation, or ultrasound irradiation. For example, in the case of temperature-responsive liposomes, stimulation of the stimulus-responsive liposomes in the cancerous tissue and / or cancer cells that are the target site for treatment acts as a trigger for the release of the encapsulated anthracycline derivative by destabilizing the liposome membrane when the temperature-responsive liposomes, which accumulate in the cancerous tissue, are heated to a temperature equivalent to hyperthermia, for example 42-43°C, preferably around 42.5°C, which can reduce or kill cancer cells.

[0048] Auger electron radiotherapy drugs, which encapsulate an anthracycline derivative containing a radioisotope-substituted benzene ring group in a stimulus-responsive liposome, are obtained by a remote loading method that utilizes the pH gradient between the stimulus-responsive liposome, where the pH of the inner aqueous layer is weakly acidic (approximately pH 4.5), and the outer aqueous layer, where the pH is approximately 7.4. This is achieved by incubating the stimulus-responsive liposome and the anthracycline derivative containing the radioisotope-substituted benzene ring group at 37°C for 1 hour. When this Auger electron radiotherapy drug is administered to a living organism with cancer tissue by an appropriate administration method such as intravenous injection, and the cancer tissue is heated, the anthracycline derivative containing the radioisotope-substituted benzene ring group is released, translocated to the nucleus of cancer cells, and Auger electrons are released.

[0049] Such a stimulus-responsive liposome containing an anthracycline derivative with a radioisotope-substituted benzene ring group (illustrated as a radiohalogen-labeled DNA-targeted drug-containing temperature-responsive liposome) is used as follows, referring to Figure 1. As shown in Figure (A), this Auger electron-responsive liposome is injected into the body by intravenous injection. Then, as shown in Figure (B), the Auger electron-responsive liposome infiltrates the cancer tissue from the blood vessels and accumulates in the cancer tissue and / or cancer cells or their surroundings in response to the EPR effect of the stimulus-responsive liposome. As shown in Figure (C), when heated to the level of hyperthermia, the membrane of the stimulus-responsive liposome becomes unstable in response to the heating, and the anthracycline derivative with the radioisotope-substituted benzene ring group is released from the stimulus-responsive liposome and migrates to cancer cells. At the same time, the anthracycline derivative with the radioisotope-substituted benzene ring group intercalates into DNA and accumulates in the nucleus of cancer cells. Subsequently, as shown in Figure (D), Auger electrons are released from the radioisotopes in the radioisotope-substituted benzene ring-containing groups of the anthracycline derivative, thereby exhibiting an anti-cancer effect.

[0050] As an example of a stimulus-responsive liposome, we have shown one that is responsive to heating, but it may also be a photo-responsive liposome that releases the encapsulated anthracycline derivative when exposed to light such as ultraviolet light, or an ultrasound-responsive liposome that releases the encapsulated anthracycline derivative when exposed to ultrasound. In any case, the same type of stimulus-responsive liposome can be used.

[0051] Although doxorubicin was given as an example of anthracyclines, doxorubicin may also be a compound with a 2-6 carbon atom substituted for the methoxy group, as shown in the following chemical formula (4-2). [ka] As shown, a mixture of diastereomers, which are the reduced forms of the hydroxyacetyl groups from the keto group to the hydroxyl group, may be used, or any one of the diastereomers may be used.

[0052] As an anthracycline derivative, anthracyclines may be used instead of doxorubicin, such as daunorubicin. Daunorubicin is [ka] It is represented by the following chemical formula (4-4). Daunorubicin is used to treat acute myeloid leukemia, acute lymphoblastic leukemia, chronic myeloid leukemia, and Kaposi's sarcoma. Daunorubicin exerts its anticancer effect by interfering with the DNA of cancer cells, inhibiting the activity of an enzyme called topoisomerase II, and thereby inhibiting DNA replication. As anthracyclines, it may also be a compound of daunorubicin with an alkoxy group having 2 to 6 carbon atoms substituted from the methoxy group, as shown in the following chemical formula (4-4). [ka] As shown, a mixture of diastereomers, which are the reduced forms of the acetyl groups from the keto group to the hydroxyl group, may be used, or any one of the diastereomers may be used.

[0053] As an anthracycline derivative, examples were shown in which an Auger electron-emitting radioisotope-substituted benzene ring-containing group is N-substituted to the amino group of the 3-amino-2,3,6-trideoxy-hexopyranose ring skeleton of anthracyclines. However, these anthracyclines may also have an Auger electron-emitting radioisotope-substituted benzene ring-containing group bonded by substitution, addition, or dehydration to the hydroxyacetyl group, the keto group of the acetyl group, or its reduced alcohol group, or to the hydroxyl group of the 7,8,9,10-tetrahydronaphthacene-5,12-dione skeleton or the 3-amino-2,3,6-trideoxy-hexopyranose ring skeleton in the anthracycline skeleton.

[0054] Considering the ability of such Auger electron radiotherapy drugs to reach cancer tissue and its cancer cells from the blood vessels, the dosage form of anticancer drugs is preferably an intravenous injection.

[0055] In such anticancer drugs, it is preferable that Auger electron radiotherapy is included in an amount of, for example, 1 MBq or more. [Examples]

[0056] The Auger electron radiotherapy and anticancer agents using the same, as examples to which the present invention is applied, will be described in detail below.

[0057] (Example 1 of synthesis of anthracycline derivative containing radioisotopes, and Reference Example 1 of synthesis of anthracycline derivative without radioisotopes) The following chemical formula (5) [ka] The Auger electron radiotherapy drug shown was synthesized. The synthesis method is as follows:

[0058] [ka] [ka]

[0059] First, the non-radioactively labeled compound (5') corresponding to compound (5) was synthesized by the following method: 50.0 mg of doxorubicin hydrochloride dissolved in 5.0 mL of methanol was mixed with 40.0 mg of 4-iodobenzaldehyde, stirred at room temperature for 3 hours, then 2.71 mg of cyanobolohydride was added, stirred at room temperature overnight, and the solvent was removed by distillation under reduced pressure. The crude product was purified by silica gel column chromatography using chloroform and methanol as eluents to obtain 15.0 mg of compound (6') (yield 23%). The mass spectrometry result of compound (6') was found to be the theoretical value C 34 H 34 INO 11 [M+H] + The m / z values ​​of 760.12 and 759.98 support these structures. To 10.0 mg of compound (6') dissolved in 500 μL of N,N-dimethylformamide (DMF), 9.28 mg of 4-nitrophenyl 2-(pyridine-2-yldisulfanyl)ethyl carbonate, 1.61 mg of 4-(dimethylamino)pyridine (DMAP), and 4.59 μL of N,N-diisopropylethylamine (DIPEA) were added. After stirring overnight at room temperature, the mixture was purified by reverse-phase HPLC using a Cosmosil 5C18-AR-II column (10 × 150 mm; Nacalai Tesque) with 0.1% TFA-containing water and 0.1% TFA-containing methanol as eluents, yielding 2.3 mg of compound (A) (18% yield). The mass spectrometry results for compound (A) showed that the theoretical value was C 42 H 42 IN2O 13 S2[M+H] + The measured values ​​of m / z (m / z) = 973.12 and 973.08 support these structures. 2.00 mg of compound (A) dissolved in 200 μL of DMF was mixed with 2.04 mg of c(RGDfC) and 1.53 μL of DIPEA. After stirring at room temperature for 1 hour, the mixture was purified by reverse-phase HPLC using a Cosmosil 5C18-AR-II column (10 × 150 mm; Nacalai Tesque) with 0.1% TFA-containing water and 0.1% TFA-containing methanol as eluents, yielding 2.0 mg of compound (5') (68% yield). The mass spectrometry results of compound (5') showed that the theoretical value C was obtained.61 H 71 IN9O 20 S2[M+H] + The fact that :m / z = 1440.33 and the measured value is 1140.33 supports these structures. On the other hand, compound (5) was synthesized by the following method: 50.0 mg of doxorubicin hydrochloride dissolved in 5.0 mL of methanol was mixed with 68.3 mg of 4-tributylsuzubenzaldehyde, stirred at room temperature for 3 hours, then 2.71 mg of cyanobolohydride was added, stirred at room temperature overnight, and the solvent was removed by distillation under reduced pressure. The crude product was purified by silica gel column chromatography using chloroform and methanol as eluents to obtain 16.1 mg of compound (B) (yield 25%). The mass spectrometry result of compound (B) was found to be the theoretical value C. 46 H 61 NO 11 Sn[M+H] + The measured values ​​of m / z (m / z) = 924.33 and 924.28 support these structures. 5.0 mg of compound (B) dissolved in 500 μL of DMF was mixed with 3.82 mg of 4-nitrophenyl 2-(pyridine-2-yldisulfanyl)ethyl carbonate, 0.662 mg of DMAP, and 1.89 μL of DIPEA. After stirring overnight at room temperature, the mixture was purified by reverse-phase HPLC using a Cosmosil 5C18-AR-II column (10 × 150 mm; Nacalai Tesque) with 0.1% TFA-containing water and 0.1% TFA-containing methanol as elution solvents to obtain compound (C) as a red oil. The mass spectrometry results of compound (C) were found to be consistent with the theoretical value C. 54 H 69 N2O 13 S2Sn[M+H] + The measured values ​​of m / z (m / z) = 1137.33 and 1137.14 support these structures. A small amount of compound (C) dissolved in 50 μL of DMF was mixed with 0.100 mg of c(RGDfC) and 0.10 μL of DIPEA, stirred at room temperature for 1 hour, and then purified by reverse-phase HPLC using a Cosmosil 5C18-AR-II column (10 × 150 mm; Nacalai Tesque) with 0.1% TFA-containing water and 0.1% TFA-containing methanol as elution solvents to obtain compound (D) as a red oil. The mass spectrometry results of compound (D) were found to be in line with the theoretical value C.73 H 98 N9O 20 S2Sn[M+H] + The m / z ratio is 1604.54, and the measured value is 1604.34, which supports these structures. A small amount of compound (D) dissolved in 5 μL of acetonitrile was mixed with 3 μL of [ 125 The solution was obtained by adding a solution of [I]NaI (3.7 MBq), 10 μL of 1% acetonitrile acetate solution, and 15 μL of 1 mg / mL N-chlorosuccinimide (NCS) acetonitrile solution, stirring at room temperature for 5 minutes, and then purifying it by reverse-phase HPLC using a Cosmosil 5C18-AR-II column (10 × 150 mm; Nacalai Tesque) with 0.1% TFA-containing water and 0.1% TFA-containing methanol as eluents. A non-radioactive labeled compound (5') corresponding to compound (5), 125 High-performance liquid chromatography (HPLC) analysis was performed on the labeled compound (5). The analytical conditions were: Column: COSMOSIL 5C 18 -AR-II 4.6ID × 150 mm (manufactured by Nacalai Tesque Co., Ltd.; product name), flow rate: 1.0 mL / min, temperature: 40℃, mobile phase: A) 0.1% TFA in H2O, and B) 0.1% TFA in MeOH, A / B mixture: 40 / 60 → 20 / 80 (20 min). The chromatogram is shown in Figure 2. In addition, 125 The radiochemical yield of the I-labeled compound (5) was fractionated by HPLC and measured with a gamma counter. The yield was 30%, and the radiochemical purity was over 95%. This physicochemical analysis supports the structure of chemical formula (5).

[0060] (Preparation Example 1) The Auger electron radioactive therapeutic agent represented by the chemical formula (5) above was diluted with the medium RPMI1640 to a concentration of 3.7 kBq / mL as an anticancer agent.

[0061] (Evaluation Test 1-1: In vitro evaluation of the uptake performance of Auger electron radiotherapy drugs into cells) The Auger electron radioactive therapeutic agent represented by the aforementioned chemical formula (5), diluted in a medium, was exposed to Colon-26 cells, which are mouse colon cancer cells, and incubated for 10 minutes, 30 minutes, 1 hour, 3 hours, and 6 hours. After incubation, the cells were washed with PBS and 0.2 M glycine buffer (pH 3.0), detached with trypsin, and collected. Radioactivity was measured using a gamma counter, and then protein quantification was performed. Cellular uptake performance at the cell surface and inside the cell was evaluated by dividing the radioactivity (%dose) at the cell surface or inside the cell relative to the added radioactivity by the amount of protein (mg). The results are shown in Figure 3. Note that α is highly expressed in cancer cells of the primary tumor site. v Figure 3 also shows comparative reference data after 6 hours of simultaneous (blocking) addition (blocking) of a large amount of c(RGDfK), a peptide containing a high affinity RGD sequence, to β3 integrin. As is clear from Figure 3, uptake into the cell interior occurred in a time-dependent manner up to 1 hour, and there was almost no change thereafter. On the other hand, uptake on the cell surface was extremely low and time-independent. In contrast, in a blocked comparative reference with a large amount of RGD sequence-containing peptide added, the amount of specific intracellular uptake decreased when compared at 6 hours. It is known that RGD peptides first manifest on the surface and then move into the interior, and this result indicates that Auger electron radiotherapy drugs exhibit similar behavior.

[0062] (Evaluation Test 1-2: In vitro evaluation of the uptake performance of Auger electron radiotherapy drugs into the nucleus) In evaluation test 1-1, cells were detached with trypsin and collected after 10 minutes, 30 minutes, 1 hour, 3 hours, and 6 hours. These cells were suspended in cell lysis buffer, the supernatant was removed, and the remaining precipitate was used as the nucleus. Radioactivity was measured using a gamma counter. Nuclear uptake was evaluated as in evaluation test 1-1, by dividing the nuclear radioactivity (%dose) relative to the added radioactivity by the protein amount (mg). The results are shown in Figure 4. Additionally, Figure 4 also shows comparative reference data obtained 6 hours after blocking by simultaneous addition of a large amount of RGD sequence-containing peptide, similar to evaluation test 1-1. As is clear from Figure 4, uptake into the cell nucleus proceeded sufficiently even after 10 minutes and remained at a similar level until 6 hours. On the other hand, in a blocked comparative reference group administered in large doses of RGD sequence-containing peptide, there was no significant difference when comparing the levels at 6 hours, indicating that nuclear uptake is not related to the accumulation of RGD sequence-containing peptide in cancer tissue and / or cancer cells. Although not shown in the diagram, an amide group is used instead of the -SS- group of the reduction-responsive linker to form the RGD peptide. 125 In a comparative example where I-labeled doxorubicin was conjugated, the nuclear uptake performance was less than 10%, confirming the importance of the reduction-responsive linker in the Auger electron radiotherapy drug of Synthesis Example 1.

[0063] (Evaluation Test 1-3: In vitro evaluation of the cancer cell-damaging performance of Auger electron radiotherapy drugs) The cytotoxicity of cancer cells at different concentrations of Auger electron radiopharmaceuticals was evaluated by exposing Colon-26 cells to Auger electron radiopharmaceuticals with radioactivity levels ranging from 0 to 111 kBq / mL, adding WST reagent after 48 hours, and measuring the absorbance at 450 nm after 1 hour. Cell viability was calculated using the absorbance of the group without Auger electron radiopharmaceutical as 100%. The results are shown in Figure 5. As is clear from Figure 5, Auger electron radiotherapy drugs were shown to damage, reduce, or kill cancer cells in a concentration-dependent manner (i.e., in an Auger electron emission dose-dependent manner).

[0064] (Synthesis Example 2) The following chemical formula (6) [ka] The Auger electron radiotherapy drug shown was synthesized. The synthesis method is as follows:

[0065] [ka]

[0066] First, the non-radioactively labeled compound (6') corresponding to compound (6) was prepared by adding 40.0 mg of 4-iodobenzaldehyde to 50.0 mL of doxorubicin hydrochloride dissolved in 5.0 mL of methanol, stirring at room temperature for 3 hours, then adding 2.71 mg of cyanobolohydride, stirring overnight at room temperature, removing the solvent under reduced pressure, and purifying the crude product by silica gel column chromatography using chloroform and methanol as eluents to obtain 15.0 mg (yield 23%). The mass spectrometry result of compound (6') was found to be the theoretical value C 34 H 34 INO 11 [M+H] + The fact that :m / z = 760.12 and the measured value is 759.98 supports these structures. Compound (6) was synthesized by the following method: 50.0 mg of doxorubicin hydrochloride dissolved in 5.0 mL of methanol was mixed with 68.3 mg of 4-tributylsuzubenzaldehyde, stirred at room temperature for 3 hours, then 2.71 mg of cyanobolohydride was added, stirred at room temperature overnight, and the solvent was removed by vacuum distillation. The crude product was purified by silica gel column chromatography using chloroform and methanol as eluents to obtain 16.1 mg of compound (B) (yield 25%). The mass spectrometry result of compound (B) was found to be the theoretical value C. 46 H 61 NO 11 Sn[M+H] + The m / z ratio is 924.33, and the measured value is 924.28, which supports these structures. 50 μg of compound (B) dissolved in 20 μL of acetonitrile is mixed with 3 μL of [ 125[I]NaI (3.7 MBq) solution, 10 μL of 5% acetonitrile acetate solution, and 10 μL of 5 mg / mL chloramine T aqueous solution were added, and after stirring at room temperature for 10 minutes, 10 μL of 10 mg / mL sodium bisulfite aqueous solution was added, and the solution was purified by reverse-phase HPLC using a Cosmosil 5C18-AR-II column (10 × 150 mm; Nacalai Tesque) with 0.1% TFA-containing water and 0.1% TFA-containing methanol as eluents. A non-radioactive labeled compound (6') corresponding to compound (6), 125 High-performance liquid chromatography (HPLC) analysis was performed on the labeled compound (6). The analytical conditions were: Column: COSMOSIL 5C 18 -AR-II 4.6ID × 150 mm (manufactured by Nacalai Tesque Co., Ltd.; product name), flow rate: 1.0 mL / min, temperature: 40℃, mobile phase: A) 0.1% TFA in H2O and B) 0.1% TFA in MeOH, A / B mixture: 45 / 55 → 25 / 75 (20 min). The chromatogram is shown in Figure 6. In addition, 125 The radiochemical yield of the I-labeled compound (6) was fractionated by HPLC and measured with a gamma counter. The yield was 60%, and the radiochemical purity was over 95%. The results of this physicochemical analysis support the structure of chemical formula (6).

[0067] (Synthesis Example 3) The following chemical formula (7) [ka] The Auger electron radiotherapy drug shown was synthesized. The synthesis method is as follows:

[0068] [ka]

[0069] First, to obtain the non-radioactively labeled compound (7') corresponding to compound (7), 5.0 mg of daunorubicin hydrochloride dissolved in 1.0 mL of methanol was mixed with 2.1 mg of 4-iodobenzaldehyde and 2.39 mg of DIPEA, stirred at room temperature for 3 hours, then 0.56 mg of cyanobolohydride was added, stirred at room temperature overnight, and the solvent was removed by distillation under reduced pressure. The crude product was purified by silica gel column chromatography using chloroform and methanol as eluents to obtain 2.7 mg (41% yield). The mass spectrometry result of compound (7') was found to be the theoretical value C. 34 H 34 INO 10 [M+H] + The fact that :m / z = 744.12 and the measured value is 744.11 supports these structures. Compound (7) was synthesized by the following method: 5.0 mg of daunorubisi hydrochloride dissolved in 1.0 mL of methanol was mixed with 3.51 mg of 4-tributylsuzubenzaldehyde and 2.39 mg of DIPEA, and stirred at room temperature for 3 hours. Then, 0.56 mg of cyanobolohydride was added, and the mixture was stirred at room temperature overnight. The solvent was removed by distillation under reduced pressure, and the crude product was purified by silica gel column chromatography using chloroform and methanol as eluents to obtain 5.7 mg of compound (E) (yield 71%). The mass spectrometry result of compound (E) was found to be the theoretical value C 46 H 61 NO 11 Sn[M+H] + The m / z ratio is 908.33, and the measured value is 908.19, which supports these structures. 50 μg of compound (E) dissolved in 20 μL of acetonitrile, to which 3 μL of [ 125 [I]NaI (3.7 MBq) solution, 10 μL of 5% acetonitrile acetate solution, and 10 μL of 5 mg / mL chloramine T aqueous solution were added, and after stirring at room temperature for 10 minutes, 10 μL of 10 mg / mL sodium bisulfite aqueous solution was added, and the solution was purified by reverse-phase HPLC using a Cosmosil 5C18-AR-II column (10 × 150 mm; Nacalai Tesque) with 0.1% TFA-containing water and 0.1% TFA-containing methanol as eluents. A non-radioactive labeled compound (7') corresponding to compound (7), 125High-performance liquid chromatography (HPLC) analysis was performed on the labeled compound (7). The analytical conditions were: Column: COSMOSIL 5C 18 -AR-II 4.6ID × 150 mm (manufactured by Nacalai Tesque Co., Ltd.; product name), flow rate: 1.0 mL / min, temperature: 40℃, mobile phase: A) 0.1% TFA in H2O and B) 0.1% TFA in MeOH, A / B mixture: 45 / 55 → 25 / 75 (20 min). The chromatogram is shown in Figure 7. In addition, 125 The radiochemical yield of the I-labeled compound (7) was fractionated by HPLC and measured with a gamma counter. The yield was 30%, and the radiochemical purity was over 95%.

[0070] (Preparation Example 2) An anticancer agent containing the Auger electron radioactive therapeutic agent represented by the chemical formulas (6) to (7) above was prepared by dissolving it in ethanol and diluting it in a medium such as RPMI1640 or a phosphate buffer to obtain a 1% ethanol solution. A test solution for evaluation was prepared.

[0071] (Evaluation Test 2-1: In vitro evaluation of the uptake performance of Auger electron radiotherapy drugs into cells) Except for using the evaluation test solution for Auger electron radiotherapy represented by chemical formulas (6) to (7), measuring uptake both on the cell surface and inside the cell, and not performing blocking measurements with RGD peptide, the uptake performance into cells was measured in the same manner as in evaluation test 1-1 described above. The results for the evaluation test solution for Auger electron radiotherapy represented by chemical formulas (6) to (7) are shown in Figure 8(a).

[0072] (Evaluation Test 2-2: In vitro evaluation of the uptake performance of Auger electron radiotherapy drugs into the nucleus) The uptake performance into the nucleus was measured in the same manner as in evaluation test 1-2, except that the measurement was performed using the evaluation test solution for Auger electron radiotherapy represented by chemical formulas (6) to (7). The results for the evaluation test solutions of the Auger electron radiotherapy drugs of chemical formulas (6) to (7) are shown in Figure 8(b). As is clear from Figure 8, cells nuclear The uptake into the body occurred within 0.5 to 3 hours, and all Auger electron radiotherapy drugs represented by chemical formulas (6) and (7) showed high values. This indicates that these compounds, like the compound represented by chemical formula (5), exhibit equivalent effects as Auger electron radiotherapy drugs.

[0073] (Evaluation Test 2-3: In vitro evaluation of the cancer cell-damaging performance of Auger electron radiotherapy drugs) The cancer cell damaging performance of Auger electron radiotherapy drugs at different concentrations was measured in the same manner as in evaluation tests 1-3 described above, except that the measurement was performed using an evaluation test solution for Auger electron radiotherapy drugs represented by chemical formula (6). The results are shown in Figure 9. As is clear from Figure 9, the Auger electron radioactive therapeutic agents represented by chemical formula (6) all demonstrated that cancer cells were damaged, reduced, or killed in a concentration-dependent manner (i.e., in an Auger electron emission dose-dependent manner).

[0074] (Evaluation Test 2-4: In vivo evaluation of the pharmacokinetics of Auger electron radiotherapy drugs in cancer tissue) The Auger electron radioactive therapeutic agent, represented by chemical formula (6), was encapsulated in temperature-responsive liposomes using a remote loading method utilizing a pH gradient with an evaluation test solution. Temperature-responsive liposomes containing 37 kBq of the Auger electron radioactive therapeutic agent (represented by chemical formula (6)) were administered to mice via tail vein injection under isoflurane anesthesia. After warming the tumors at 43°C for 1 hour, the mice were euthanized, and after organ removal, the in vivo distribution of each organ in Colon-26 tumor-bearing mice was measured by measuring organ weight and radioactivity using a gamma counter. For comparison, a group was also prepared in which the tumors were not warmed at 43°C, and the kinetic effects of the Auger electron radioactive therapeutic agent on cancer tissue under warming / non-warming conditions were measured. The results are shown in Figure 10. As is clear from Figure 10, Auger electron radiotherapy drugs were shown to accumulate more readily in cancer cells under heated conditions than under unheated conditions.

[0075] (Synthesis Example 4: Reference) The following chemical formula (8) [ka] The Auger electron radiotherapy drug shown was synthesized. The synthesis method is as follows:

[0076] [ka]

[0077] First, to obtain the non-radioactive labeled compound (8') corresponding to compound (8), 8.0 mg of doxorubicin hydrochloride and 20.1 mg of 4-iodo-3-hydroxybenzaldehyde were dissolved in 3 mL of a 2:1 mixture of acetonitrile and water. Then, 55.2 μL of 1 M tetrahydrofuran solution of cyanobolohydride was added, and the mixture was stirred for 48 hours. After removing the solvent under reduced pressure, the crude product was purified by silica gel column chromatography using chloroform and methanol as eluents to obtain 3.6 mg (57% yield). The mass spectrometry result of compound (8') was found to be the theoretical value C. 34 H 36 INO 11 [M+Na]+ The fact that :m / z = 800.1 and the measured value is 800.0 supports these structures. Compound (8) was synthesized by the following method: 8.0 mg of doxorubicin hydrochloride and 10.1 mg of 4-hydroxybenzaldehyde were dissolved in 3 mL of a 2:1 mixture of acetonitrile and water. Then, 55.2 μL of 1 M tetrahydrofuran solution of cyanobolohydride was added, and the mixture was stirred for 48 hours. After removing the solvent under reduced pressure, the crude product was purified by silica gel column chromatography using dichloromethane and methanol as eluents to obtain 4.0 mg (71% yield). The mass spectrometry result of compound (F) was found to be the theoretical value C. 34 H 35 NO 12 [M+H] + The m / z ratio is 652.2, and the measured value is 652.3, which supports these structures. 80 μg of compound (F) dissolved in 20 μL of acetonitrile, to which 2 μL of [ 125 [I]NaI (370 kBq) solution, 50 μL of 25% acetonitrile acetate solution, and 15 μL of 20 mg / mL chloramine T aqueous solution were added, and the mixture was stirred at 60°C for 5 minutes. Then, 10 μL of 8 mg / mL sodium bisulfite aqueous solution was added, and the solution was purified by reverse-phase HPLC using a Cosmosil 5C18-AR-II column (10 × 150 mm; Nacalai Tesque) with 0.1% TFA-containing water and 0.1% TFA-containing methanol as eluents. A non-radioactive labeled compound (8') corresponding to compound (8), 125 High-performance liquid chromatography (HPLC) analysis was performed on the labeled compound (8). The analytical conditions were: Column: COSMOSIL 5C 18 -AR-II 4.6ID × 150 mm (manufactured by Nacalai Tesque Co., Ltd.; product name), flow rate: 1.0 mL / min, temperature: 30℃, mobile phase: A) 0.1% TFA in H2O and B) 0.1% TFA in MeOH, A / B mixture: 40 / 60 → 20 / 80 (20 min). The chromatogram is shown in Figure 11. In addition, 125The radiochemical yield of the I-labeled compound (8) was fractionated by HPLC and measured with a gamma counter, showing a yield of 56% and a radiochemical purity of over 95%.

[0078] (Evaluation Test 3-1: In vitro evaluation of the uptake performance of Auger electron radiotherapy drugs into cells) Except for using a test solution for evaluating Auger electron radiopharmaceuticals represented by chemical formula (8), measuring only intracellular uptake, and not performing measurements that blocked with RGD peptide, the uptake performance into cells was measured in the same manner as in evaluation test 1-1 described above. The results are shown in Figure 12(a). As is clear from Figure 12(a), the uptake into the cell took 0.5 to 3 hours, and the evaluation test solutions for Auger electron radiotherapy drugs represented by chemical formulas (5) to (7) shown in Figures 3 and 8 showed nuclear uptake values ​​that were several to tens of times higher than those for the evaluation test solution for Auger electron radiotherapy drugs represented by chemical formula (8).

[0079] (Evaluation Test 3-2: In vitro evaluation of the uptake performance of Auger electron radiotherapy drugs into the nucleus) Except for using the evaluation test solution for Auger electron radiotherapy represented by chemical formula (8) and not performing measurements that blocked with RGD peptide, the cell uptake performance was measured in the same manner as in evaluation test 1-2 described above. The results are shown in Figure 12(b). As is clear from Figure 12(a), the evaluation test solutions for Auger electron radiotherapy drugs represented by chemical formulas (5) to (7) in Figures 4 and 8, and the evaluation test solution for Auger electron radiotherapy drugs represented by chemical formula (8), both showed equivalent values ​​of uptake into the nucleus.

[0080] As is clear from the results above, the Auger electron radioactive therapeutic agent to which the present invention is applied has been shown to accumulate in cancer tissue and release Auger electrons into the nucleus of cancer cells, thereby reducing or killing cancer cells. [Industrial applicability]

[0081] The Auger electron radiotherapy drug to which the present invention is applied is useful as a medicine administered to cancer patients to reduce or kill cancer cells in cancer tissue.

Claims

1. Anthracycline derivatives, selected from doxorubicin or daunorubicin and their reduced forms from the keto group to the hydroxyl group, or their alkoxy group-substituted forms with 2-6 carbon atoms from the methoxy group, have an Auger electron-emitting radioisotope-substituted benzene ring-containing group or radioisotope-substituted alkyl group covalently bonded to the keto, amino, or hydroxyl group of anthracyclines, They are encapsulated in stimulus-responsive liposomes that accumulate in cancer tissue and / or cancer cells so as to be released upon stimulation, or It is bound to antibodies, oligopeptides, or antigens that accumulate in cancer tissue and / or cancer cells via a stimulus-responsive linker, so as to be cleaved and released upon stimulation. An Auger electron radiotherapy drug characterized by being such.

2. The radioactive isotope-substituted benzene ring-containing group or the radioactive isotope-substituted alkyl group contains the radioactive isotope １２５ I or ７７ The Auger electron radiotherapy drug according to claim 1, characterized in that it is Br.

3. The Auger electron radiotherapy drug according to claim 1, characterized in that the liposome, antibody, or oligopeptide accumulates in the cancer tissue and / or the cancer cells and / or their nuclei, and releases Auger electrons from the radioactive isotope by spontaneous decay.

4. The substituted benzene ring-containing group may be an alkyl group having a hydroxyl group on the benzene ring, or The radioactive isotope-substituted alkyl group may have a hydroxyl group, a halogen group, a nitro group, or a cyano group, and is a linear, branched, and / or cyclic alkyl group. The Auger electron radiotherapy drug according to feature 1.

5. The Auger electron radioactive therapeutic agent according to claim 1, characterized in that the substituted benzene ring-containing group or the radioisotope-substituted alkyl group is bonded by any of the covalent bonds selected from substitution, addition, and dehydration bonds.

6. The Auger electron radioactive therapeutic agent according to claim 1, characterized in that the stimulus is, for example, at least one selected from a reducing state, an acidic pH state, an enzyme activity state, and heating stimulation, light stimulation, and ultrasonic stimulation at the target site.

7. The Auger electron radiotherapy drug according to claim 1, characterized in that the anthracycline derivative is conjugated to the antibody, the antibody is internalized within cancer cells, and is an anti-HER2 antibody, an anti-EGFR antibody, or an anti-PD-L1 antibody.

8. The Auger electron radioactive therapeutic agent according to claim 1, wherein the anthracycline derivative is bound to the oligopeptide, and the oligopeptide is an RGD sequence-containing peptide or a prostate-specific membrane antigen.

9. The anthracycline derivative is conjugated to the antibody, oligopeptide, or antigen via the stimulus-responsive linker, wherein the stimulus-responsive linker is, for example, The following chemical formula (1) 【Chemistry 1】 A reduction-responsive linker represented by Alternatively, the following chemical formula (2-1) 【Chemistry 2】 A pH-responsive linker represented by Alternatively, it can be cleaved by enzymatic activity of cathepsin B or β-glucuronidase, as shown in the following chemical formulas (3-1) to (3-3). 【Chemistry 3-1】 【Chemistry 3-2】 【Chemistry 3-3】 An enzyme activity-responsive linker represented by one of the following groups The Auger electron radioactive therapeutic agent according to claim 1, characterized in that it is one of the following.

10. The Auger electron radioactive therapeutic agent according to claim 1, characterized in that the anthracycline derivative is encapsulated in the stimulus-responsive liposome, for example, the stimulus-responsive liposome is formed of at least 1,2-dihexadecanoyl-sn-glycero-3-phosphocholine, poly(N-isopropylacrylamide)-modified phosphoethanolamine, and / or dioleoylphosphoethanolamine, or further contains IR780 and / or perfluorocarbon.

11. The Auger electron-emitting therapeutic agent according to claim 10, characterized in that the stimulus-responsive liposome is responsive to any of the following stimuli: heating, light, or ultrasound.

12. The aforementioned anthracyclines are given by the following chemical formula (4-1) 【Chemistry 4-1】 Doxorubicin as shown by, or the following chemical formula (4-2) 【Chemistry 4-2】 The reduced form of doxorubicin from the keto group to the hydroxyl group shown by, or a diastereomer of only one of them, or the following chemical formula (4-3) 【Chemistry 4-3】 The daunorubicin shown in, or the following chemical formula (4-4) 【Chemistry 4-4】 The reduced form of daunorubicin from the keto group to the hydroxyl group, or a diastereomer of only one of these, as shown above. The Auger electron radiotherapy drug according to claim 1, characterized in that it is the same as described in claim 1.

13. An anticancer agent comprising the Auger electron radiotherapy agent described in claim 1, characterized in that it is an orally administered or intravenously injected agent.

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