Pt(IV) chemotherapy prodrugs and controlled-release tumor therapy

Abstract

The present disclosure provides a Pt(IV) complex for use as a prodrug that is activated by radiation to release a Pt(II) complex for treating tumors. The present disclosure further provides pharmaceutical compositions containing the Pt(IV) complex and the use of the Pt(IV) complex in the manufacture of a medicament that is activated by radiation to treat tumors. The present disclosure further provides a kit containing the Pt(IV) complex and instructions for administering the Pt(IV) complex followed by radiation therapy to treat tumors.

Description

[Technical Field]

[0001] This invention belongs to the field of medicinal chemistry. Specifically, this invention relates to Pt(IV) chemotherapy prodrugs and tumor treatment by controlled release thereof. [Background technology]

[0002] Cancer is one of the diseases that most seriously threatens human life and health. Surgery, radiation therapy, and chemotherapy are known as the three main treatments for tumors.

[0003] Radiation therapy is a local treatment method that uses radiation to treat tumors. The therapeutic effect of radiation therapy depends on radiosensitivity, and different tissues and tumor tissues respond differently to irradiation. For example, fibrosarcoma, osteosarcoma, and melanoma are tumors that are insensitive (resistant) to radiation. Radiation therapy is not effective in killing all cancer cells in a tumor, and its killing effect on hypoxic cancer cells is undesirable.

[0004] Chemotherapy uses chemical agents to kill cancer cells and achieve therapeutic objectives. Divalent platinum-based drugs possess effective and broad-spectrum anticancer activity, making them clinically important first-line chemotherapy agents. They are widely used to treat common malignancies such as lung cancer, bladder cancer, ovarian cancer, cervical cancer, esophageal cancer, gastric cancer, colorectal cancer, and head and neck tumors. Cisplatin is representative of the first generation of platinum-based anticancer agents, carboplatin and nedaplatin are representative of the second generation, and oxaliplatin and lovaplatin are representative of the third generation. The application of divalent platinum-based drugs is limited by side effects such as nephrotoxicity, gastrointestinal toxicity, hematological toxicity, neurotoxicity, and ototoxicity, and their therapeutic effect is limited by tumor drug resistance. Research on tetravalent platinum-based drugs is also progressing to expand the range of platinum-based drugs. Tetravalent platinum compounds themselves have low killing ability against cancer cells, but they can exert anticancer activity by being reduced under physiological conditions to release divalent platinum. This retains the advantage of conventional divalent platinum-based drugs, which are effective against cancer over a wide range of cells, while also offering unique advantages due to the different coordination structures of tetravalent and divalent platinum. Tetravalent platinum is d 2 sp 3 Having a six-coordinate structure, it exhibits greater stability than divalent platinum, resulting in higher blood stability. The presence of two additional ligands axially in the tetravalent platinum complex provides more options for the design of platinum-based drugs. However, despite some tetravalent platinum complexes, such as iproplatin or satraplatin, entering clinical research in the last century, the sale of tetravalent platinum-based drugs has not yet been approved. [Overview of the project] [Problems that the invention aims to solve]

[0005] Therefore, there is still a need to develop platinum-based drugs and / or regimens that are low in toxicity and highly effective in treatment. [Means for solving the problem]

[0006] Through diligent research and creative efforts, the inventors have discovered that a Pt(IV) complex can be used as a prodrug, and that by irradiating this prodrug with radiation, a divalent platinum-based drug can be released, thereby enabling the treatment of tumors. By effectively combining radiotherapy with a Pt(IV) complex, that is, by activating the Pt(IV) complex with radiation and controlling its release, the therapeutic effect can be effectively improved.

[0007] In one embodiment, the present disclosure relates to a Pt(IV) complex of formula (I) that is activated by radiation and used as a prodrug for treating tumors, [ka] (In the formula, L1 to L6 are platinum ligands.) The complex provides a Pt(IV) complex that releases L5 and L6 after irradiation to obtain the Pt(II) complex of formula (II).

[0008] [ka] Preferably, the Pt(II) complex of formula (II) is a cis-type Pt(II) complex. For example, the Pt(II) complex of formula (II) is cisplatin, carboplatin, nedaplatin, oxaliplatin, lobaplatin, heptaplatin, cycloplatin, myoplatin, enloplatin, sebriplatin, spiroplatin, zeniplatin, TRK-710, aroplatin, bis(isopropylamine)platinum(II), or bis(cyclopentylamine)platinum(II). In preferred embodiments, the Pt(II) complex of formula (II) is cisplatin, carboplatin, nedaplatin, oxaliplatin, lovaplatin, or heptaplatin.

[0009] Preferably, L5 and L6 are independent of each other. - It is OC(O)-R, where R is a C that can be arbitrarily substituted. 1-20 Alkyl group, optionally substituted C 1-20 An alkyloxy group or an optionally substituted amino group, the substituent is C 1-18 Alkyl group, carboxyl group, hydroxyl group, halogen, mercapto group, amino group, C 1-3 Dialkylamino group, carbonyl group, phenyl group, halogenated phenyl group, C 1-6 The alkyl-substituted phenyl group, maleimide group, and triphenylphosphonium group are selected independently. For example, R can be methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, carboxymethylene, 2-carboxyethylene, 3-carboxypropylene, 4-carboxybutylene, 5-carboxypentylene, 6-carboxyhexylene, (dimethylamino)methylene, 2-(dimethylamino)ethylene, 3-(dimethylamino)propylene, 4-(dimethylamino)butylene, 5-(dimethylamino)pentylene, 6-(dimethylamino)hexylene, 5-maleimidepentylene, or 6-maleimide Selected from hexylidene group, 7-maleimidoheptylene group, 8-maleimidooctylene group, 3-(4-iodophenyl)propylene group, 3-(3-iodophenyl)propylene group, 3-(3,5-diiodophenyl)propylene group, 3-(4-bromophenyl)propylene group, 3-(3-bromophenyl)propylene group, 3-(3,5-dibromophenyl)propylene group, methylamine group, ethylamine group, propylamine group, butylamino group, pentylamino group, hexylamine group, heptylamino group, octylamino group, nonylamino group, decylamino group, undecylamino group, dodecylamino group, tridecylamino group, tetradecanoylamino group, pentadecanoylamino group, hexadecanoylamino group, heptadecylamino group, and octadecanoylamino group.

[0010] Preferably, the tumor is leukemia, lung cancer, malignant lymphoma, breast cancer, ovarian cancer, soft tissue sarcoma, osteogenic sarcoma, rhabdomyosarcoma, Ewing's sarcoma, blastoma, neuroblastoma, bladder cancer, thyroid cancer, prostate cancer, head and neck tumors, nasopharyngeal cancer, esophageal cancer, testicular cancer, gastric cancer, liver cancer, pancreatic cancer, cervical cancer, endometrial cancer, melanoma, or colorectal cancer.

[0011] In another embodiment, the present disclosure provides a pharmaceutical composition comprising the Pt(IV) complex.

[0012] In another aspect, the disclosure further provides applications of the Pt(IV) complex in the manufacture of drugs activated by radiation to treat tumors. Preferably, the radiation is derived from radiotherapy.

[0013] In another aspect, the present disclosure further provides a method for treating a tumor, comprising administering the Pt(IV) complex to a subject and irradiating the subject.

[0014] Preferably, the radiation exposure is derived from radiotherapy.

[0015] Preferably, the radiotherapy is performed 0.5 to 6 hours after administration of the Pt(IV) complex.

[0016] In one embodiment, the radiation dose is less than 60 Gy.

[0017] Preferably, the tumor is leukemia, lung cancer, malignant lymphoma, breast cancer, ovarian cancer, soft tissue sarcoma, osteogenic sarcoma, rhabdomyosarcoma, Ewing's sarcoma, blastoma, neuroblastoma, bladder cancer, thyroid cancer, prostate cancer, head and neck tumors, nasopharyngeal cancer, esophageal cancer, testicular cancer, gastric cancer, liver cancer, pancreatic cancer, cervical cancer, endometrial cancer, melanoma, or colorectal cancer.

[0018] In another aspect, this disclosure is: The Pt(IV) complex or a pharmaceutical composition containing the Pt(IV) complex, The kit includes instructions explaining that radiation therapy should be administered after administration to treat the tumor.

[0019] To more clearly illustrate the technical means of the embodiments of this disclosure, the drawings relating to the embodiments are briefly described below. Clearly, the drawings described below relate only to some embodiments of this disclosure and do not limit the invention. [Brief explanation of the drawing]

[0020] [Figure 1] It exhibits broad-spectrum properties in reducing metal ions with radiation. [Figure 2] It exhibits broad-spectrum properties in reducing metal complexes with radiation. [Figure 3] This study demonstrates that radiation drives the Pt(IV) complex to effectively release FDA-approved Pt(II) drugs over a wide area. [Figure 4] This study demonstrates that radiation can effectively induce the control of oxaliplatin release within living cells. [Figure 5] This study demonstrates the ability to combine radiotherapy and chemotherapy by reducing the oxaliPt(IV)-(OAc)2 prodrug using radiation to release oxaliplatin, and then using this for chemotherapy of oxaliplatin-sensitive cell line HCT116 tumors. [Modes for carrying out the invention]

[0021] To further clarify the purpose, technical means, and advantages of the embodiments of this disclosure, the technical means of the embodiments of this disclosure will be described clearly and completely below with reference to the drawings relating to the embodiments of this disclosure. Clearly, the embodiments described are a part of, but not all, of, the embodiments of this disclosure. All other embodiments obtained by a person skilled in the art, without any creative work, based on the embodiments of this disclosure described, are all within the scope of the protection of the present invention.

[0022] The present invention can be implemented in other specific forms without departing from the basic attributes of the present invention. It should be understood that, unless there is a contradiction, any one and all embodiments of the present invention can be combined with the technical features in any one or a plurality of other embodiments to obtain another embodiment. The present invention includes such other embodiments obtained from such combinations.

[0023] All publications and patents mentioned in this disclosure are incorporated into this disclosure by citing all of their contents. For any publication and patent incorporated by citation, if the uses or terms used therein conflict with the uses or terms used in this disclosure, the uses and terms of this disclosure shall be the standard.

[0024] The section headings used in this specification are for the sole purpose of assembling the text and should not be construed as limiting the above subject matter.

[0025] Unless otherwise specified, all technical terms and scientific terms used in this specification have the ordinary meanings in the field to which the subject matter for which protection is sought pertains. If a term has multiple definitions, the definition in this specification shall be the standard.

[0026] All numerical values such as the amounts of expression materials, reaction conditions, durations, quantitative properties of materials, etc. described in this specification and the claims should be understood to be modified by the term "about" in all cases, unless in the examples or otherwise explicitly stated. Note that any numerical range cited in this application is intended to include all sub-regions within the range and any combination of the range or sub-range with each endpoint. For example, an alkyl group having 1 to 20 carbon atoms (C 1-20 alkyl group) includes alkyl groups having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms, and sub-ranges include alkyl groups having 1 to 4, 1 to 6, 1 to 10, 2 to 4, or 2 to 10 carbon atoms, etc.

[0027] The specifications of this disclosure should be interpreted as being consistent with the laws and principles of chemical bonding. In some cases, hydrogen atoms may be removed to adapt substituents at a given position.

[0028] Similar words used in this disclosure, such as “include,” “contain,” or “incorporate,” are intended to mean that the element preceding the word covers the elements and their equivalents listed after the word, and do not exclude any elements not described. The terms “contain” or “include” as used herein may be open, semi-closed, or closed. In other words, the terms include “substantially consisting of” or “consisting of.” Please understand that the singular form used in this disclosure (e.g., "kind 1") may include multiple forms unless otherwise specified.

[0029] Unless otherwise specified, standard nomenclature and standard laboratory steps and techniques of analytical chemistry, organic synthesis chemistry, and coordination chemistry are used in this disclosure. Unless otherwise stated, conventional methods such as mass spectrometry and elemental analysis are used in this disclosure, and for each step and condition, general operating steps and conditions in the art can be referenced.

[0030] The reagents and raw materials used in this disclosure are either commercially available or produced by common chemical synthesis methods.

[0031] In this specification, when the term "optional" is used to describe a situation, it means that the situation may or may not occur. For example, "optional condensation with a ring" means that the ring may or may not condense with a ring. For example, as used herein, the term "optionally substituted" means having at least one non-hydrogen substituent that does not impair the purpose or performance of the unsubstituted analogue.

[0032] In this disclosure, unless otherwise specified, the number of “substitutions” may be one or more, and if there are multiple, there may be two, three or four. If there are multiple “substitutions,” the “substitutions” may be the same or different.

[0033] In this disclosure, unless otherwise specified, the position of “substitution” is arbitrary.

[0034] As used herein, the term "axial ligand" refers to a tetravalent platinum d 2 sp 3 This refers to the two axial ligands in the six-coordinate structure, which are eliminated from the complex after it is reduced by radiation.

[0035] As used herein, the term "transverse ligand" refers to a tetravalent platinum d 2 sp 3 This refers to the four transverse ligands in the hexa-coordinate structure, which can still coordinate with divalent platinum ions after the complex has been reduced by radiation.

[0036] As used herein, the terms "neutral ligand" or "anionic ligand" mean a ligand that can coordinate to platinum, which is either neutral or negatively charged overall, but which may have a portion of a cation, such as triphenylphosphine or an ammonium group.

[0037] In the context of this application, unless otherwise specifically stated, the term "treatment" may include prevention.

[0038] In this application, the terms "subject" or "patient" include humans and mammals.

[0039] The term "C1-C" as used herein 20The term "alkyl group" refers to a linear or branched alkane chain containing 1 to 20 carbon atoms. For example, typical examples of C1-C6 alkyl groups include, but are not limited to, methyl (C1), ethyl (C2), n-propyl (C3), isopropyl (C3), n-butyl (C4), t-butyl (C4), s-butyl (C4), isobutyl (C4), n-pentyl (C5), 3-pentane (C5), neopentyl (C5), 3-methyl-2-butane (C5), t-pentyl (C5), and n-hexyl (C6). The term "lower alkyl group" refers to a linear or branched alkyl group having 1 to 4 carbon atoms. The term "substituted alkyl group" refers to an alkyl group substituted with one or more substituents, preferably 1 to 4 substituents, at any available bond point. The term "haloalkyl group" refers to an alkyl group having one or more halogen substituents, and includes, but is not limited to, groups such as -CH2Br, -CH2I, -CH2Cl, -CH2F, -CHF2, and -CF3.

[0040] The term "alkylene group" as used herein appears to refer to the "alkyl group" described above, but it means a divalent hydrocarbon group having two bonding points. For example, a methylene group is a -CH2- group, and an ethylene group is a -CH2-CH2- group.

[0041] As used herein, the terms "alkoxy group" and "alkylthio group" refer to alkyl groups as described above, bonded via oxygen bonds (-O-) or sulfide bonds (-S-), respectively. The terms "substituted alkoxy group" and "substituted alkylthio group" refer to substituted alkyl groups bonded via oxygen bonds or sulfide bonds, respectively. A "lower alkoxy group" is an OR group in which R is a lower alkyl group (an alkyl group containing 1 to 4 carbon atoms).

[0042] As used herein, the term "halogen" means fluorine, chlorine, iodine, or bromine.

[0043] The radiation sources in this disclosure may be alpha, beta, and gamma rays produced by the decay of radionuclides. X-rays, gamma rays, high-energy electrons, protons, heavy ions, alpha particles produced by boron neutron capture therapy (BNCT), and other possible external or internal radiation may be applied to this disclosure.

[0044] High-energy beams used in radiotherapy possess high spatiotemporal resolution and high tissue penetration capabilities, as well as significant clinical relevance. Activating prodrug molecules and inducing chemical reactions within the body using high-energy beams in radiotherapy has value in both basic research and clinical applications.

[0045] Chemical reactions activated by high-energy radiation involve the decomposition of water by radiation, producing large amounts of active substances, which then react with target substrates. Among the products of radiolysis of water, the compounds with the highest yields are hydroxyl radicals and hydrated electrons.

[0046] The living environment is generally a reducing environment, and large amounts of substances such as glutathione and vitamin C quench hydroxyl radicals while increasing the yield of hydrated electrons. Thus, utilizing hydrated electrons to carry out chemical reactions is a major breakthrough in biochemistry.

[0047] High-energy radiation (e.g., X-rays and gamma rays) can be used as external stimuli to reduce tetravalent platinum complexes and obtain divalent platinum complexes. Due to the high penetration ability and spatiotemporal resolution of radiation, prodrugs can be converted to divalent platinum complexes very effectively by radiotherapy devices. For example, X-ray irradiation can be used as an external trigger to activate prodrugs, allowing for spatial and temporal control of the radiation-induced chemical reaction, thus enabling precise control of the area, time, and dose required to convert the prodrug to its active form.

[0048] This disclosure enables the release of Pt(II) drugs from Pt(IV) prodrugs by immediately and effectively reducing the properties of a metal complex with radiation, thereby achieving the objective of controlled release of chemotherapeutic drugs. Therefore, by reducing a relatively low-toxicity Pt(IV) prodrug with radiation to release a Pt(II) drug, such as oxaliplatin, various cell lines highly sensitive to oxaliplatin can be effectively suppressed. In HCT116 tumor-bearing mice, this strategy almost completely reduces the tumor. Such reduction is achieved by the radiolysis of water, which generates hydrated electrons (e aq - It is mediated by and applied to the hypoxic, reducing tumor microenvironment. Therefore, the strategy of activating prodrugs with radiotherapy to release chemotherapeutic drugs has certain clinical potential value.

[0049] In tumor treatment, more than 50% of cases require radiation therapy. Modern radiation therapy techniques allow for precise irradiation of tumors and the delivery of high-dose radiation to localized areas.

[0050] The response of cancer to radiation can be explained by its radiosensitivity. Highly radiosensitive cancer cells (leukemia, many lymphomas, and germ cell tumors) are rapidly killed by moderate doses of radiation. Moderately radiosensitive cancer cells (many epithelial cancers) require higher doses of radiation (60-70 Gy) to completely kill them. Some cancers (renal cell carcinoma and melanoma) have significant radioactivity and require doses far higher than the clinically safe dose for a cure. Many common moderately radioresponsive tumors are generally treated with radiation therapy when in the early stages. Metastatic cancers are generally not cured by radiation therapy because it cannot treat the entire body.

[0051] Radiation therapy itself is painless. Many low-dose, temporary palliative therapies (e.g., radiation therapy for bone metastases) have few or no side effects. Higher doses result in different side effects, including acute side effects during the treatment period, long-term side effects (months or years after treatment), or cumulative side effects after retreatment. The nature, severity, and duration of side effects depend on the irradiated organ, type of radiation, dose, number of doses, synchronized chemotherapy, and the patient. Side effects are dose-dependent; for example, relatively high doses of head and neck radiation can cause cardiovascular complications, thyroid dysfunction, and pituitary dysfunction. Modern radiation therapy aims to minimize side effects and help patients understand and manage unavoidable side effects.

[0052] Radiation therapy destroys the DNA of cancer cells using photons or charged particles. It directly or indirectly ionizes the atoms that make up the DNA strand. Indirect ionization involves the formation of radicals through the ionization of water, which destroys the DNA. Cells have mechanisms to repair DNA damage, and repairing breaks in double-stranded DNA is more difficult, potentially leading to significant chromosomal abnormalities and gene deletions. Targeted double-strand breaks increase the likelihood of cell death. Experiments conducted by Gray et al. in the 1950s showed that three times the radiation dose was required to kill hypoxic cells compared to normal cells. Due to the limited resistance of normal tissue to radiation, it is generally not possible to compensate for the hypoxic state of tumors by increasing the radiation dose. After radiation therapy, hypoxic tumor cells persist and divide, potentially leading to the persistent presence of the tumor and the development of a more invasive tumor phenotype.

[0053] While radiotherapy has limitations on the clinically permissible radiation dose (generally less than 60 Gy), hypoxic tumors develop resistance to radiotherapy and are unfavorable to DNA damage caused by fixed oxygen radiation. Therefore, to improve tumor cure rates, radiotherapy often needs to be combined with chemotherapy drugs. However, many clinically approved anticancer drugs have narrow therapeutic windows and high systemic toxicity, often requiring the introduction of prodrug strategies to further increase dosage and reduce toxicity. Prodrug doses exceed 50 times the normal dose and can overcome tumor resistance to chemotherapy drugs to some extent. However, prodrug strategies are difficult to implement clinically due to their limited activation efficiency and poor tumor selectivity. Using radiotherapy as a precise external stimulus can highly selectively activate the active drug at the tumor site, solving these challenges. However, the in vivo radioactive degradation chemistry has not yet been established, and in the past 30 years, only limited work has realized this strategy at the test tube or cell level. However, unless the chemical reaction for radiation activation is established in vivo, the activation of chemotherapy drugs induced by radiotherapy will have little clinical impact.

[0054] The radiochemical changes of molecules are the material basis for studying all radiochemical effects. Radiochemical effects are mainly of two types: direct effects, in which ionizing radiation directly causes chemical changes in target molecules, and indirect effects, in which radiation accumulates on environmental molecules and then causes indirect chemical reactions in target molecules. Direct and indirect effects coexist, but indirect effects play a dominant role in living organisms. Since 70-80% of tissue is water, various active substances are mainly produced by the radiolysis of water (Scheme 1a), with hydroxyl radicals (·OH) and hydrated electrons (e) being the most abundant. aq - ) is. The radiolysis of water is 10 -4Because the reaction is completed within seconds, radiation-induced reactions often occur instantaneously, offering high controllability. While the decomposition chemical reactions induced by γ-OH and associated fluorescent probes have been successfully applied to in vivo imaging, rapid quenching of γ-OH by the reducing tumor microenvironment inhibits the in vivo development of γ-OH. aq - The yield of, i.e., the yield of another major product of radiolysis of water in a reducing environment increases. Therefore, here, the inventors have demonstrated how to precisely apply radiotherapy to a local area. aq - We study the feasibility of generating a substance to mediate a chemical shear reaction (Scheme 1b), and use radiation as a chemical tool to release target molecules in a highly tumor-selective manner (Scheme 1c).

[0055] [ka] Scheme 1a [ka] Scheme 1b (M is Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, etc.) [ka] Scheme 1c Scheme 1: Controlled release of metal complexes in tumors induced by radiation. a. Radiolysis of water by ionizing radiation. The G value of hydrated electrons is 2.63 (the G value is the number of molecules formed by absorbing 100 eV of energy in the system). b. Hydrated electrons generated by radiation can reduce metal ions and metal complexes. c. Pt(IV) complexes can be reduced by radiation and release the Pt(II) anticancer agent.

[0056] The inventors have developed a novel bioshear chemistry to achieve radiation-induced metal reduction in vivo through their research. Applying this strategy to the activation of Pt(IV) prodrugs, and using radiotherapy as an external stimulus to trigger drug release, the release of chemotherapy drugs to tumor sites can be completed under precise guidance of radiotherapy. Furthermore, this strategy contributes to solving the problem of radiotherapy resistance in hypoxic tumors, and can even improve drug release efficiency under hypoxic conditions. aq - Inducing direct metal reduction can be extended to other metals or biocomplexes (e.g., metalloproteins), providing an effective tool for analyzing the mechanisms of complex biological processes.

[0057] A Pt(IV) complex of formula (I) according to one aspect of this disclosure is activated by radiation and used as a prodrug for treating tumors. [ka] In the formula, L1 to L6 are platinum ligands, and the complex releases L5 and L6 after irradiation to obtain the Pt(II) complex of formula (II).

[0058] [ka] The Pt(IV) complex of formula (I) in this disclosure releases axial ligands L5 and L6 upon reduction to obtain the Pt(II) complex of formula (II). The Pt(IV) complex of formula (I) was developed based on the Pt(II) complex and can be considered a prodrug of the Pt(II) complex of formula (II). From the correspondence between formula I and formula II above, the transverse ligands L1 to L4 of the Pt(IV) complex of formula (I) can be determined from the ligands L1 to L4 of the Pt(II) complex of formula (II).

[0059] The transverse ligand of the Pt(IV) complex of formula (I) may be in cis or trans form. In one embodiment, the transverse ligand of the Pt(IV) complex of formula (I) is in cis form.

[0060] In one embodiment, the Pt(II) complex of formula (II) is a cis-type Pt(II) complex.

[0061] The Pt(II) complex of formula (II) may be a divalent platinum ligand known to have anticancer activity. In one embodiment, the Pt(II) complex of formula (II) is a commercially available or clinically used divalent platinum complex, such as cisplatin, carboplatin, nedaplatin, oxaliplatin, lobaplatin, heptaplatin, cycloplatin, myoplatin, enloplatin, sebriplatin, spiroplatin, zeniplatin, TRK-710, Aroplatin, bis(isopropylamine)platinum(II), or bis(cyclopentylamine)platinum(II).

[0062] In preferred embodiments, the Pt(II) complex of formula (II) is cisplatin, carboplatin, nedaplatin, oxaliplatin, lovaplatin, or heptaplatin.

[0063] L5 and L6 are negative monovalent ligands of Pt(IV) that can be released from the Pt(IV) complex of formula (I) under irradiation, respectively. L5 and L6 may be the same or different.

[0064] In one embodiment, L5 and L6 are, respectively - It is OC(O)-R, where R is a C that can be arbitrarily substituted. 1-20 Alkyl group, optionally substituted C 1-20 An alkyloxy group or an optionally substituted amino group, the substituent is C 1-18 Alkyl group, carboxyl group, hydroxyl group, halogen, mercapto group, amino group, C 1-3 Dialkylamino group, carbonyl group, phenyl group, halogenated phenyl group, C 1-6 Selected from alkyl-substituted phenyl groups, maleimide groups, and triphenylphosphonium groups. Here, "arbitrarily substituted" means C 1-20 This means that the alkyl group or amino group may or may not be substituted with a substituent. 1-20Alkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl groups. Those skilled in the art will rationally select substituents according to the stability of the chemical structure.

[0065] In one embodiment, L5 and L6 are independently - OC(O)-R, where R is independently a methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, carboxymethylene group, 2-carboxyethylene group, 3-carboxypropylene group, 4-carboxybutylene group, 5-carboxypentylene group, 6-carboxyhexylene group, (dimethylamino)methylene group, 2-(dimethylamino)ethylene group, 3-(dimethylamino)propylene group, 4-(dimethylamino)butylene group, 5-(dimethylamino)pentylene group, 6-(dimethylamino)hexylene group, 5-maleimidepentylene group, 6-maleimide Selected from imidohexylidene group, 7-maleimidoheptylene group, 8-maleimidooctylene group, 3-(4-iodophenyl)propylene group, 3-(3-iodophenyl)propylene group, 3-(3,5-diiodophenyl)propylene group, 3-(4-bromophenyl)propylene group, 3-(3-bromophenyl)propylene group, 3-(3,5-dibromophenyl)propylene group, methylamine group, ethylamine group, propylamine group, butylamino group, pentylamino group, hexylamine group, heptylamino group, octylamino group, nonylamino group, decylamino group, undecylamino group, dodecylamino group, tridecylamino group, tetradecanoylamino group, pentadecanoylamino group, hexadecanoylamino group, heptadecylamino group, and octadecanoylamino group.

[0066] For example, platinum(IV) complexes are compounds 1 to 22, which are cisplatin-based prodrugs.

[0067] [ka] Here, [Table 1-1] [Table 1-2] For example, platinum(IV) complexes are compounds 23 to 44, which are carboplatin-based prodrugs.

[0068] [ka] Here, [Table 2-1] [Table 2-2] For example, platinum(IV) complexes are compounds 45-66, which are prodrugs derived from oxaliplatin.

[0069] [ka] Here, [Table 3-1] [Table 3-2] Regarding platinum(IV) complexes, the divalent platinum complex of formula (II) can be hydroxylated with an oxidizing agent, such as hydrogen peroxide, to obtain a platinum(IV) dihydroxy complex. The two dihydroxy groups in the platinum(IV) dihydroxy complex may be substituted with carboxylate groups by the action of an acylating agent, such as an anhydride.

[0070] For example, platinum(IV) complexes can be produced by the following scheme.

[0071] [ka] The corresponding Pt(II) drug A (12.6 mmol, 1.0 equivalent) was mixed with 12 mL of H2O2, diluted with 15 mL of H2O, and stirred at 50°C for 5 hours. After completely consuming the Pt(II) drug, the product was collected in a centrifuge tube at room temperature, washed with water, ethanol, and ethyl ether respectively, and the precipitate was freeze-dried to obtain a white powder of compound B.

[0072] Compound II (1.0 equivalent) and the corresponding acid anhydride (e.g., succinic anhydride, acetic anhydride, N,N-dimethylglycine anhydride) (1.0 equivalent) were mixed, dissolved in 4 mL of anhydrous DMF, and then stirred for 1 hour to obtain unpurified compound C.

[0073] Regarding compound D (where urethane bond, i.e., R2 represents an amino compound), Two mL of the corresponding isocyanate in anhydrous DMF solution was added to the above reaction mixture. The mixture was allowed to react overnight, and the solvent was removed under reduced pressure at 65°C. Two mL of ethyl ether was added to the oily residue, and the mixture was sonicated for one minute and centrifuged. The solid was further washed with four mL of DCM and two mL of ethyl ether. The washed solid was left in a vacuum overnight to obtain compound D.

[0074] Regarding compound D (where the ester bond, i.e., R2, represents an alkyl compound), Compound C was precipitated with ethyl ether and freeze-dried to obtain a white powder. Compound C (1.0 equivalent) and the corresponding carboxylic acid (2.0 equivalents) were dissolved in 5 mL of DMF, and the condensing agent TBTU (2.0 equivalents) was added. The mixture was heated to 50°C and reacted overnight in the dark. After evaporating the solvent under reduced pressure, the mixture was washed with water to precipitate, and then freeze-dried in a freeze-dryer to obtain compound D.

[0075] The tetravalent platinum complex described herein is thought to treat tumors primarily by being reduced to divalent platinum in vivo. When the tetravalent platinum complex is administered (oral, intravenous, or intracavitary), the drug is distributed to most organs and tissues throughout the body via the bloodstream, but the level of reduction to divalent platinum varies depending on the cells in each organ and tissue. However, subsequent radiotherapy can precisely irradiate the tumor and deliver a localized high dose of radiation, thereby locally increasing the level of reduction of tetravalent platinum to divalent platinum.

[0076] The tetravalent platinum complex prodrugs of this disclosure can be used to treat leukemia, lung cancer, malignant lymphoma, breast cancer, ovarian cancer, soft tissue sarcoma, osteogenic sarcoma, rhabdomyosarcoma, Ewing's sarcoma, blastoma, neuroblastoma, bladder cancer, thyroid cancer, prostate cancer, head and neck tumors, nasopharyngeal cancer, esophageal cancer, testicular cancer, gastric cancer, liver cancer, pancreatic cancer, cervical cancer, endometrial cancer, melanoma, or colorectal cancer.

[0077] Another aspect of this disclosure provides a pharmaceutical composition comprising the above-mentioned Pt(IV) complex and pharmaceutically acceptable auxiliary materials.

[0078] In this application, the terms “pharmaceutically acceptable” or “pharmaceutically acceptable” mean that the compound or composition is chemically and / or toxicologically compatible with the other components of the formulation and / or with the human or mammal to whom the disease or condition is to be prevented or treated.

[0079] In this application, the term "auxiliary material" refers to an excipient or medium for administering a compound, and includes, but is not limited to, diluents, disintegrants, precipitation inhibitors, surfactants, flow aids, adhesives, lubricants, and coatings. Auxiliary materials are generally described in EW Martin's "Remington's Pharmaceutical Sciences." Examples of auxiliary materials include, but are not limited to, vegetable oils, cyclodextrins, aluminum monostearate, aluminum stearate, carboxymethylcellulose, sodium carboxymethylcellulose, crospovidone, glyceryl isostearate, glyceryl monostearate, hydroxyethylcellulose, hydroxymethylcellulose, hydroxydioctadecyl hydroxystearate, hydroxypropylcellulose, hydroxypropylmethylcellulose, lactose, lactose monohydrate, magnesium stearate, mannitol, and microcrystalline cellulose.

[0080] At least one embodiment of the present disclosure provides a method for producing a pharmaceutical composition, the method comprising mixing at least one Pt(IV) complex of the present disclosure with a pharmaceutically acceptable auxiliary material.

[0081] The Pt(IV) complex of this disclosure can be prepared as an injectable and a powdered injectable, and is administered intravenously after dilution with physiological saline or a 5% glucose solution.

[0082] Divalent platinum-based drugs are generally administered parenterally and are not suitable for oral administration. However, the Pt(IV) complexes of this disclosure can also be prepared as pharmaceutical compositions for oral administration.

[0083] For example, an orally administered pharmaceutical composition comprises a suspension of at least one Pt(IV) complex in a pharmaceutically acceptable vegetable oil, animal oil, mineral oil, synthetic oil, or semi-synthetic oil. In one embodiment, the pharmaceutical composition may be encapsulated in a hard gelatin capsule, a hydroxypropyl methylcellulose capsule, or a soft gelatin capsule, each capsule containing 50 to 350 mg of the Pt(IV) complex.

[0084] For example, an orally administered pharmaceutical composition may include an inclusion complex of cyclodextrin and a Pt(IV) complex, which is obtained by dissolving the Pt(IV) complex in an organic solvent, such as acetone, then reacting it with cyclodextrin, such as a β or γ cyclodextrin substituted with a C1-4 hydroxyalkyl group, followed by sublimation and drying under reduced pressure to remove the solvent.

[0085] This disclosure further provides applications for the above-mentioned Pt(IV) complex in the manufacture of drugs activated by radiation to treat tumors.

[0086] In another aspect, the disclosure further provides a method for treating a tumor, comprising administering the Pt(IV) complex to a subject and irradiating the subject with radiation.

[0087] In one embodiment, the radiation exposure is derived from radiotherapy.

[0088] Radiation therapy includes external beam radiation therapy (including general external beam radiation therapy, stereotactic radiation therapy, conformal radiation therapy, and intensity-modulated radiation therapy), particle beam therapy, Auger therapy, contact X-ray proximity therapy (particle intervention therapy), and radioisotope therapy.

[0089] Available equipment includes deep X-ray therapy machines, cobalt-60 therapy machines, medical electron linear accelerators, medical proton accelerators, medical heavy ion accelerators, and gamma knives.

[0090] The radiotherapy described herein differs from synchronized radiotherapy. Synchronized radiotherapy improves the sensitivity of tissue to radioactivity with low-dose chemotherapy, whereas the radiotherapy described herein promotes the reduction of prodrugs to divalent platinum-based drugs through radiation exposure simultaneously with chemotherapy. The radiotherapy described herein differs from sequential chemoradiotherapy. Sequential chemoradiotherapy involves administering one set of chemotherapy followed by one set of radiotherapy, or one set of radiotherapy followed by one set of chemotherapy, whereas the radiotherapy described herein involves administering radiotherapy a short time after chemotherapy, for example, 0.5 to 6 hours later.

[0091] In one embodiment, the radiotherapy described above is performed 0.5 to 6 hours after the administration of the Pt(IV) complex.

[0092] For example, the above radiotherapy is performed 0.5h, 1h, 1.5h, 2h, 2.5h, and 3h after administering the Pt(IV) complex, with radiation therapy administered for 1 to 10 minutes (for example, 1, 2, 3, 4, and 5 minutes).

[0093] For example, the radiotherapy device is a linear accelerator (e.g., Varian Medical Systems' Clinac iX), which generates X-rays with an energy of 6 MeV, with a total local irradiation dose of 4 Gy to the tumor and a dose rate of 2 Gy / min. The regimen involves treatment twice a week (one treatment consists of drug therapy and radiotherapy), with radiotherapy administered 2 hours after the administration of the Pt(IV) complex, each radiotherapy session lasting approximately 2 minutes, with a 2-day interval between sessions, and this needs to be repeated for a total of 4 weeks.

[0094] [ka] The radiotherapy with Pt(IV) complexes described herein can treat hypoxic tumors that cannot be treated with conventional radiotherapy, such as pancreatic cancer and prostate cancer.

[0095] The radiotherapy scheme of this disclosure may be carried out by general radiotherapy methods, or by doses lower than those of general radiotherapy methods, and when carried out by doses lower than those of general radiotherapy, the side effects of radiotherapy can be reduced.

[0096] In one embodiment, the radiation dose is less than 60 Gy.

[0097] The Pt(IV) complex of this disclosure can be used in combination with radiotherapy to treat cancers such as leukemia, lung cancer, malignant lymphoma, breast cancer, ovarian cancer, soft tissue sarcoma, osteogenic sarcoma, rhabdomyosarcoma, Ewing's sarcoma, blastoma, neuroblastoma, bladder cancer, thyroid cancer, prostate cancer, head and neck tumors, nasopharyngeal cancer, esophageal cancer, testicular cancer, gastric cancer, liver cancer, pancreatic cancer, cervical cancer, endometrial cancer, melanoma, or colorectal cancer.

[0098] In yet another embodiment, the disclosure further provides a kit comprising the Pt(IV) complex or a pharmaceutical composition comprising the Pt(IV) complex and instructions explaining that the tumor is treated by radiotherapy after administration.

[0099] Examples The starting materials for the examples are commercially available and / or can be prepared by various methods well known to those skilled in the art of organic synthesis. Those skilled in the art of organic synthesis will appropriately select the reaction conditions (including solvent, reaction atmosphere, reaction temperature, duration of experiment, and workup) from the synthesis methods described below. Those skilled in the art of organic synthesis will understand that the functional groups present in each part of the molecule should be compatible with the proposed reagents and reactions.

[0100] Reagents and equipment All chemical reagents are purchased from Energy Chemical Industry (China), Bailingwei (China), Inuokai (China), and China National Medical Group (China), and are used as is without requiring further purification. Solvents are dehydrated with Na or CaH2 before use and then distilled. Cell counting kit-8 (CCK-8) is purchased from Biyuntian Biotechnology Institute. The ultrapure water (18.2 MΩ / cm) used throughout the process is from a Milli-Q reference system (Millipore). Nuclear magnetic resonance (NMR) spectra are recorded using a Brooke AVANCE 400 MHz spectrometer. Ultra-high-performance liquid chromatography-mass spectrometry (UPLC-MS) is performed using an ACQUITY UPLC H-Class PLUS instrument equipped with a Waters PDA eλ detector and a Waters Acquity QDA mass spectrometer. Absorption spectra are measured using a UV-1100 spectrophotometer. X-ray irradiation is generated by an X-ray generator (RS2000 Pro 225, 225kV, 17.7mA, Rad Source Technologies, Inc.). The total dose for single-tube experiments is 0-60 Gy, with a dose rate of 5 Gy / min. The total dose for cell experiments is 0-16 Gy, with a dose rate of 1.6 Gy / min. Local irradiation is performed on transplanted tumors using a customized mouse model. The local irradiation dose to the tumor is 4 Gy, with a dose rate of 1 Gy / min, and the rest of the body is shielded with 5 mm thick lead. Gamma ray irradiation is performed. 60 Provided by Co-source

[0101] 1. Synthesis and Characterization of Pt(IV) Complexes As previously mentioned, the Pt(IV) complex is produced by the corresponding Pt(II) drug, oxidized with hydrogen peroxide to obtain a platinum(IV) dihydroxy complex, and the two dihydroxy groups of the platinum(IV) dihydroxy complex react with the corresponding acid anhydride to produce compounds 1 to 66. The products are characterized by mass spectrometry.

[0102] [Table 4-1] [Table 4-2] [Table 4-3] 2.Analysis method 2.1 Detection of iron ions and complexes Fe 2+ / Fe 3+ For the storage solution, 2.78 mg of FeSO4·7H2O and 2.70 mg of FeCl3·6H2O were each dissolved in 1 mL of deionized water to obtain a 10 mM storage solution, and 100 μL of this storage solution was diluted to 100 μM with 10 mL of water.

[0103] Fe 2+ / Fe 3+ For the probe, 54.06 mg of phenanthroline is dissolved in 1 mL of DMSO to obtain a 300 μM storage solution, which can be used for detection without further dilution. 2.48 mg of Fe 3+ The probe was dissolved in 1 mL of DMSO to obtain a 10 mM stock solution, and 100 μL of this solution was diluted to 100 μM with 10 mL of MeOH / H2O (v / v, 1:1).

[0104] [Fe(phen))3] 2+ For the solution, 15 μL of phenol stock solution and 15 mL of 100 μM Fe 2+ In addition to the solution, [Fe(phen)3] 2+ A complex was obtained.

[0105] Fe by phen 2+ / Fe 3+ For the detection of Fe, 100 μM Fe 2+ / Fe 3+ The solution was further decayed to 80 μM, 60 μM, 40 μM, 20 μM, and 0 μM. 3 mL of the above Fe 2+ / Fe 3+ Since 3 μL of phenol storage solution was added to the solution, the final phenol concentration was 300 μM, and the Fe concentration was hardly affected. UV-Vis absorption was detected at 510 nm.

[0106] Fe 2+ / Fe 3+ Fe 3+ Detected with a probe. 100 μM Fe 2+ / Fe 3+ The solution was further decayed to 80 μM, 60 μM, 40 μM, 20 μM, and 0 μM. 600 μL of Fe 2+ / Fe 3+ Solution and 2400 μL of Fe 3+ Because it was mixed with the probe, Fe 2+ / Fe 3+ The final concentrations were 20 μM, 16 μM, 10 μM, 8 μM, 4 μM, and 0 μM, and Fe 3+ The probe concentration was 80 μM. The reaction system was incubated at 37°C for 20 minutes and detected at 450 nm using a UV-Vis spectrophotometer.

[0107] [ka] 2.2 Detection of copper ions and complexes Cu 2+ For the storage solution, 2.50 mg of CuSO4·5H2O was dissolved in 1 mL of deionized water to obtain a 10 mM storage solution.

[0108] Cu 2+ For the probe, 34.25 mg of sodium diethyldithiacarbamate was dissolved in 1 mL of DMSO to obtain a 200 mM storage solution.

[0109] Cu by sodium diethyldithiacarbamate 2+ For the detection of Cu, 100 μL of 10 mM Cu 2+ The stock solution was diluted to 100 μM with 10 mL, and then further decayed to 80 μM, 60 μM, 40 μM, 20 μM, and 0 μM. 3 mL of the above Cu 2+ Since 3 μL of sodium diethyldithiocarbamate stock solution was added to the solution, the final concentration of phen was 200 μM, and Cu 2+ The concentration of [substance] was hardly affected. Ultraviolet-visible absorption at 450 nm was detected.

[0110] 2.3 Detection of Nickel Ions and Complexes Ni 2+ For the storage solution, 2.38 mg of NiCl2·6H2O was dissolved in 1 mL of deionized water to obtain a 10 mM storage solution, and 100 μL of this solution was diluted to 125 μM with 8 mL of water.

[0111] For the dimethylacetaldehyde oxime (DMG) solution, 89 mg of DMG was dissolved in 1.5 mL of 10 M NaOH (aq) to obtain a 0.51 M solution.

[0112] For the K2S2O8 solution, 57 mg of K2S2O8 was dissolved in 1.5 mL of deionized water to obtain a 0.14 mmol solution.

[0113] Ni 2+ For detection, 125 μM Ni 2+ The solution was further decayed to 100 μM, 75 μM, 50 μM, 25 μM, and 0 μM. 50 μL of K2S2O8 solution, 100 μL of 1 M NaOH(aq), and 50 μL of DMG solution were sequentially added to 800 μL of Ni. 2+ Because it was added to the solution, Ni 2+ The final concentrations were 100 μM, 80 μM, 60 μM, 40 μM, 20 μM, and 0 μM. The reaction system was incubated at 25°C for 20 minutes and detected at 530 nm using a UV-Vis spectrophotometer.

[0114] 2.4 Detection of ions / complexes without probes A 10 mM storage solution of the metal ion or complex and the corresponding compound was prepared and sequentially diluted to 100 μM, 80 μM, 60 μM, 40 μM, 20 μM, and 0 μM. The ion or complex was detected by the following method.

[0115] 1. ICP-AES [Table 5] 2. Detection of ultraviolet-visible spectra [Table 6] 3. UPLC-MS [Table 7] 2.5 Detection of ligand release of Pt(IV) complex 1 in different solutions A 10 mM stock solution of Pt(IV) complex 1 was prepared and diluted to 100 μM with a solution of H2O, PBS, 5 mM Tyr, Trp, DMEM, CM (complete medium), and FBS. After irradiation with X-rays, 200 μL of ACN was added to each solution, and the supernatant was obtained by centrifugation. This process was repeated two more times until the final concentration was 1 / 8 of the original concentration. Ligand release was detected by UPLC-MS and quantified using a coumarin calibration curve.

[0116] 2.6 Detection of the release status of corresponding platinum-based drugs from Pt(IV)-(Suc)2 195 Measurement by Pt NMR (Figure 3, d, e, f) Pt(IV)-(Suc)2 was dissolved in 1 mL of deuterium water (80 mmol), and the pH was adjusted to 7 using NaOH. After deoxygenation, the solution was exposed to 40 kGy of gamma radiation. 60 Co source, 200 Gy / min, 200 min). After the reaction is complete, add DMSO to redissolve the precipitate to obtain (oxaliPt(IV)-(Suc)2), or use the clarified solution after the reaction to obtain (cisPt(IV)-(Suc)2, carboPt(IV)-(Suc)2). 195 Pt NMR measurements were performed.

[0117] Product determination by UPLC-MS (Figure 3b, c) oxaliPt(IV)-(Suc)2 was dissolved in 1 mL of deionized water (1 mM) and the pH was adjusted to 7 using NaHCO3. After deoxygenation, the solution was exposed to 1 kGy of gamma radiation. 60 Co source, 100 Gy / min, 10 min). The crude reaction product was analyzed by UPLC-MS, and it was determined that the product released by UPLC-MS was oxaliplatin.

[0118] 2.7 Measurement of emission efficiency by UPLC-MS The corresponding tetravalent platinum complexes (compounds 1-66) were dissolved in DMSO to obtain a tetravalent platinum reservoir (10 mM), which was then diluted to 10 μM with pure water. After deoxygenation, the solution was irradiated with 60 Gy of X-rays (4 Gy / min, 15 min). The crude reaction product was analyzed by UPLC-MS, and it was determined that the released product was the corresponding divalent platinum-based drug. The concentration of the divalent platinum-based drug was determined using an external standard curve for platinum-based drugs, and the release efficiency was calculated.

[0119] 3. Biological methods 3.1 Cell culture The BGC823 cell line was obtained from the National Cell Line Resource Infrastructure (Beijing, China). HCT116, Ls513, HT29, and LoVo were purchased from the American Type Culture Collection (ATCC). HCT116, Ls513, HT29, and BGC823 were grown in RPMI-1640 (Roswell Park Memorial Institute-1640) medium containing 10% FBS and 1% penicillin / streptomycin. LoVo cells were grown in Ham's F-12K (Roswell Park Memorial Institute-1640) medium containing 10% FBS and 1% penicillin / streptomycin. All cell cultures were cultured at 37°C and 5% carbon dioxide. 3.2 Measurement of Cell Viability Cell activity was evaluated using the CCK-8 detection method. Each test was repeated three times.

[0120] To detect the cytotoxicity of oxaliPt(IV)-(OAc)2, HCT116, Ls513, LoVo, HT29, and BGC823 were used at concentrations of 5 × 10⁻¹⁶. 4RPMI-1640 or F-12K medium containing 10% FBS and 1% penicillin / streptomycin at a concentration of cells / mL was inoculated into 96-well plates and incubated for 24 hours in a 37°C 5% CO2 incubator. Cells and 10 μM oxaliPt(IV)-(OAc)2 were cultured under hypoxic conditions for 24 hours. Subsequently, cells were irradiated with 8 Gy of X-rays and incubated for a further 3 days. After incubation, blank medium containing CCK-8 at a final concentration of 0.5 mg / mL was added to the cells. The 96-well plates were incubated at 37°C 5% CO2 for 2 hours, and absorbance was measured at 450 nm. The absorbance of the treated cells was compared to that of the control group, and the survival rate of the untreated control group was set to 100%.

[0121] 3.3 Tumor Models All animal experiments were conducted in accordance with standards approved by the Peking University Ethics Committee.

[0122] Six-week-old female Nu / Nu mice were purchased from Victoria Laboratory (Beijing, China) and raised under specific conditions free from pathogens and with sufficient water and food. 2 × 10 6 A tumor xenograft model was constructed by subcutaneously injecting 100 μL of PBS containing 1 HCT116 cells into the right shoulder of a mouse. The tumor volume was 1 / 2 length * width 2 That is the case.

[0123] The tumor volume is 50 mm 3 Treatment was initiated when the tumor reached a certain stage (approximately 6 days), and the regimen is shown in Figure 5. Based on the pharmacokinetics of oxaliPt(IV)-(OAc)2, the mice received a 1-hour injection of the prodrug, followed by radiotherapy, i.e., 4 Gy of X-rays were irradiated to the tumor area. The body weight and tumor size of the mice were recorded every two days, and when the tumor size of the mouse reached 1500 mm, 3 If the threshold was exceeded, the mice were euthanized in accordance with the guidance of the ethics committee. Records were kept continuously from the start of treatment for the mice until day 40.

[0124] Effect of radiotherapy dose on metal reduction efficiency In industry, generally, wastewater is treated with radiation of 10 - 500 kGy to precipitate toxic heavy metal ions in contaminated water. Therefore, in this study, first, attempts were made to irradiate an FeCl3 (100 μM, aq) solution with X-rays of 10 - 60 Gy (the dose of clinical radiotherapy) (a in Fig. 1). 1,10-Phenanthroline is a classical probe for detecting the Fe 3+ / Fe 2+ redox reaction, and the aqueous solution of Fe(phen)3 3+ is colorless, while Fe(phen)3 2+ is orange. Immediately after irradiation, 1,10-phenanthroline (30 mM, DMSO) (the final concentration of 1,10-phenanthroline is 300 μM) was added to the FeCl3 solution, and the solution immediately turned orange (b in Fig. 1), explaining the formation of Fe 2+ . The calibration curve of Fe(phen)3 2+ was used to determine that the yield of Fe 2+ has a linear relationship with the radiation absorption dose (c in Fig. 1). In addition, Fe 3+ was quantitatively detected, and it was found that the consumption of Fe 3+ is approximately equal to the production amount of Fe 2+ (Fig. 1c). Therefore, Fe 2+ is the main product of reducing Fe 3+ by radiation.

[0125] The hydrated electron is one of the strongest reducing agents in water (standard electrode potential, -2.77 V) and is also one of the main products of the radiation decomposition of water (~280 nM / Gy). The inventors hypothesized that radiation-driven metal reduction is mediated by e aq - generated by the radiation decomposition of water. By irradiating Fe 3+ with radiation in 10 mM methanol, t-butyl alcohol, and sodium formate solutions, the result that Fe 2+ was generated proved that a reducing environment (·OH quencher) is favorable for the occurrence of this reaction. NaNO3 and saturated oxygen solution, that is, known e aq - quenchers, were used for Fe 2+This significantly reduces the amount of emissions (Figure 1d). aq - Since radiation-mediated reduction is generally applicable to most transition metals, a series of representative metal ions (100 μM, aq) are tested under the same conditions (60 Gy of X-rays), and the reduction yield is determined by the absorbance of the corresponding complex or by other methods. As shown in Figure 1e, radiation-driven reduction reactions are feasible in most cases. The reduction yield of metals by radiation can reach as high as 240 nM / Gy, and e aq - It is close to the theoretical yield.

[0126] Figure 1 illustrates the broad-spectrum nature of the reduction of metal ions by radiation. Fe 3+ / Fe 2+ The redox reaction was detected using 1,10-phenanthroline (phen). 3+ Immediately after irradiating the solution with X-rays (0-60 Gy), phen was added to quantitatively form an orange complex with Fe(II) (λ max =510nm), Fe 3+ (100 μM, aq) is Fe 2+ It is proven that it drives reduction to . A schematic diagram (a) and photograph (b) of the titration staining method of radiation-driven reduction are shown. In c, Fe 3+ The consumption of [Fe(phen)3] 2+ It is approximately equal to the amount produced and has a linear relationship with the absorbed radiation dose. Its G value is 200 nM / Gy, and e aq - This is close to the theoretical G value (280 nM / Gy). In d, when treated with a hydroxyl radical quencher, radiation-driven Fe 3+ / Fe 2+ The yield of the reduced amount increases, e aq - When treated with a quencher, it decreases. In e, radiation-driven reduction of metal ions is generally applied to transition metals.

[0127] Subsequently, this study further investigates the feasibility of reducing metal complexes with radiation. When the reduction potential of a metal complex changes, the reactivity of radiation-induced reduction may decrease. Therefore, the inventors prepared 100 μM metal complexes, deoxygenated them, and irradiated them with 0-60 Gy of X-rays. We are pleased that the metal complexes also yielded good results. From the calibration curves for each metal complex, the radiation-driven reduction yield of metals exceeded 200 nM / Gy, and for some metals, it may even reach 350 nM / Gy (Figure 2a), e aq - It is found that the theoretical yield is exceeded. This is because metal atoms with higher atomic numbers deposit more X-ray energy, increasing the amount of ionizing radiation. Therefore, the reaction of reducing metals with radiation has the characteristics of being broad, effective, and highly selective, and its development as a tool for shear chemistry in living organisms is desired.

[0128] Furthermore, UPLC-MS analysis after radioactive reduction of Pt(IV) complex 1 detected the release of the axial ligand. Because Pt(IV) derivatives have high clinical application potential, the next step is to test the effects of radioactive reduction in the biological environment, i.e., the realization of radiation-driven activation of the Pt(IV) drug substance in tumors. To test biocompatibility, the Pt(IV) complex was dissolved in PBS, 5 mM Tyr, 5 mM Trp, Dulbecco's Modified Medium (DMEM), and Complete Medium (CM), and UPLC-MS analysis was performed after irradiation. As shown in Figure 2b, the release of the axial ligand of Pt(IV) complex 1 was achieved in all of the above solutions. Since the reaction yield in complete fetal bovine serum (FBS) was not significantly different from that in water, the strategy of reducing Pt(IV) complex 1 by radiation to release the axial ligand is highly feasible even under complex in vivo conditions.

[0129] Figure 2 illustrates the broad spectrum of reduction of metal complexes by radiation. In a, the transition metal complex may be reduced by medical dose radiation, and the reduction yield is e aq -The yield is higher than the theoretical yield. Furthermore, the Pt(IV) complex (left figure, 100 μM, 1% DMSO aqueous solution) can release axial ligands after being reduced by radiation. In b, the Pt(IV) complex (100 μM) was reduced by radiation under various biological conditions (Tyr is tyrosine, Trp is tryptophan, 5 mM, DMEM medium, CM complete medium, FBS, fetal bovine serum), and the release of the corresponding axial ligands was detected by UPLC.

[0130] Such radiation-driven release mechanisms have two possibilities. The release of the axial ligand of the Pt(IV) complex can be achieved by hydrolysis or reduction. Hydrolysis cleaves the ester bond to obtain Pt(IV)-(OH)2 and the axial ligand, and reduction changes the valence of the platinum element to produce the corresponding divalent platinum-based drug. According to ligand field theory, 5d 6 The most common coordination number for Pt(IV) with a valence electron configuration is 6, and 5d 8 Pt(II), with its valence electron configuration, tends to form tetragonal complexes. As is evident from existing studies of Pt(IV) prodrugs, the reduction of Pt(IV) to Pt(II) results in a decrease in coordination number and release of ligands.

[0131] To elucidate the reaction process, first, a solution of oxaliPt(IV)-(Suc)2 (80 mM, D2O) was deoxidized, followed by 40 kGy of gamma radiation. 60 The solution was irradiated with a Co source at 200 Gy / min for 200 minutes (Figure 3a), and detected by UPLC-MS. Only one new peak was observed, and its retention time (Figure 3b) and mass spectrometry signal (Figure 3c) were consistent with those of the oxaliplatin standard sample. The product was analyzed by nuclear magnetic resonance (NMR). 195As shown in the Pt-NMR spectrum, the 1615 ppm peak of the Pt(IV) complex almost disappears after irradiation (top of Figure 3d), and a new single peak appears at -1988 ppm (middle of Figure 3d), which is within the chemical shift range of the Pt(II) complex and matches the chemical shift of oxaliplatin (bottom of Figure 3d). All of the above experiments demonstrate that the release of the axial ligand is due to radiation reduction of Pt(IV) and not hydrolysis.

[0132] To investigate the universality of this strategy, the inventors conducted similar studies on two other platinum-based drugs commonly used worldwide, carboplatin and cisplatin. Through nuclear magnetic resonance characterization, they discovered that cisPt(IV)-(Suc)2 and carboPt(IV)-(Suc)2 release the corresponding Pt(II) drug after irradiating D2O with gamma rays (Figure 3e, f). Given the broad applications of platinum-based drugs in chemotherapy, the proposed strategy of controlling Pt(II) release after driving the reduction of Pt(IV) prodrugs with radiation is highly desirable for realizing precise radiation-driven chemotherapy.

[0133] Figure 3 illustrates how radiation drives a Pt(IV) complex to effectively release FDA-approved Pt(II) drugs over a wide area. a is a schematic diagram showing how radiation drives the release of Pt(II) drugs from a Pt(IV) complex. b is a UPLC chromatogram of oxaliPt(IV)-(Suc)2, oxaliPt(IV)-(Suc)2+ radiation, oxaliplatin, and oxaliPt(IV)-(OH)2, with reference to oxaliplatin and oxaliPt(IV)-(OH)2. The main product released by radiation-driven oxaliPt(IV)-(Suc)2 has the same retention time as oxaliplatin. The detector wavelength was set to 254 nm. In c, the MS of the product released by radiation-driven oxaliPt(IV)-(Suc)2 indicates that the released product is oxaliplatin. In sections d-f, nuclear magnetic resonance (NMR) was used to study the Pt(II) drug released from the Pt(IV) complex. Section d shows oxaliPt(IV)-(Suc)2 (1615 ppm, top), irradiation product (-1988 ppm, middle), and external standard (bottom). 195 This is a Pt-NMR spectrum. e represents cisPt(IV)-(Suc)2 (1082 ppm, top), irradiation product (-2150 ppm, middle), and external standard (bottom). 195 This is a Pt-NMR spectrum. f is the concentration of carboPt(IV)-(Suc)2 (1883 ppm, top), irradiation product (1707 ppm, middle), and external standard (bottom). 195 This is a Pt-NMR spectrum. 195 Pt-NMR spectra demonstrate that radiation-driven release of FDA-approved Pt(II) drugs is effective and widely applicable to Pt(IV) complexes.

[0134] The key to successful prodrug development lies in balancing the demands for stability and reactivity under physiological conditions. A fatal drawback of metal complexes in chemotherapeutic drugs is their limited biological stability. In fact, most Pt(IV) prodrugs reported to date can release Pt(II) anticancer agents that are active under intracellular bioreducible conditions. Therefore, the biological stability of Pt(IV) prodrugs is a crucial prerequisite for realizing this strategy. Based on existing research, tetracarboxyPt(IV) has a clear advantage in terms of stability. Accordingly, we further designed oxaliPt(IV)-(OAc)2 (Figure 4a), which has two carboxyl groups as axial ligands and, under the physiological environment in vivo, has two negative charges and therefore cannot be effectively concentrated in tumors. Accordingly, oxaliPt(IV)-(OAc)2 exhibits high stability and reactivity, and after incubation with 20 equivalents of Vc for 24 hours, over 95% of oxaliPt(IV)-(OAc)2 remains sufficiently stable (Figure 4b). After irradiating oxaliPt(IV)-(OAc)2 (10 μM PBS solution, deoxygenated) with 0-60 Gy of X-rays, it was found that the released oxaliplatin showed a positive correlation with a predetermined radiation dose (Figure 4c). The toxicity of oxaliPt(IV)-(OAc)2 to oxaliplatin-sensitive cell lines, such as HCT116, HT29, LoVo, and Ls513 (human colorectal cancer cell lines), is two to three orders of magnitude lower than that of oxaliplatin, and its IC50 is approximately submicromolar.

[0135] To verify whether radiation-driven oxaliplatin is released into the cellular environment and exerts its anti-cancer function, the inventors performed oxaliPt(IV)-(OAc)2+X-ray cell viability assays using several cell lines. In this experiment, complete medium was used as a control, and cells were treated with 8 Gy of X-rays, 10 μM of oxaliPt(IV)-(OAc)2, and 10 μM of oxaliPt(IV)-(OAc)2+8 Gy of X-rays, respectively. After 96 hours of culture, the CCK-8 assay showed that the cell activity of the group treated with 10 μM of oxaliPt(IV)-(OAc)2+8 Gy of X-rays was significantly lower than that of the group treated with 10 μM of oxaliPt(IV)-(OAc)2 or 8 Gy of X-rays alone (Figure 4d), indicating the feasibility of the strategy of releasing oxaliplatin from oxaliPt(IV)-(OAc)2 within the cell.

[0136] Figure 4 illustrates the effectiveness of radiation-induced control of oxaliplatin release within living cells. Figure a is a schematic diagram showing how radiation drives the release of oxaliplatin from the prodrug oxaliPt(IV)-(OAc)2, a widely used chemotherapeutic drug. Figure b shows the stability of the oxaliPt(IV)-(OAc)2 prodrug. When 10 μM oxaliPt(IV)-(OAc)2 was incubated with 20 equivalents of Vc (200 μM), over 95% of the oxaliPt(IV)-(OAc)2 remained stable after 24 hours. Figure c shows oxaliplatin released by 10 μM oxaliPt(IV)-(OAc)2 at clinically relevant doses (0-60 Gy, X-rays), with an efficiency of up to 70%. d shows a cell viability assay for controlled extracorporeal release of oxaliplatin (prodrug oxaliPt(IV)-(OAc)2 = 10 μM (h), X-ray, 8 Gy, n = 6). HCT116, LoVo, Ls513, and HT69 are human colorectal cancer cells that are highly sensitive to oxaliplatin.

[0137] To find the optimal dosage, the inventors evaluated the effects of different doses of oxaliplatin and prodrugs on the health of healthy mice. Similar to the therapeutic administration regimen, mice were administered once every two days, and their body weight curves were recorded. Injections of 3 μmol / kg of oxaliplatin or 30 μmol / kg of oxaliPt(IV)-(OAc)2 did not cause a decrease in mouse body weight, but oxaliplatin above 10 μmol / kg and oxaliPt(IV)-(OAc)2 at 100 μmol / kg showed clear side effects, resulting in a decrease in mouse weight (Figure 5a). When the oxaliplatin dose reached 30 μmol / kg, the mice experienced a severe decrease in body weight, dying on day 8 and all dying on day 16 (Figure 5b). Long-term survival and body weight curves of mice indicate that 3 μmol / kg of oxaliplatin and 30 μmol / kg of oxaliPt(IV)-(OAc)2 can be administered at appropriate doses without significant side effects. To achieve optimal radiotherapy efficacy, the inventors investigated the optimal radiotherapy time by studying the pharmacokinetics of oxaliPt(IV)-(OAc)2 in HCT116 tumor-bearing mice using ICP-MS. 30 μmol / kg of oxaliPt(IV)-(OAc)2 was injected into HCT116 tumor-bearing mice via tail vein injection, and the mice were killed at a predetermined time. Subsequently, the concentrations of platinum-based drugs in the blood, tumors, liver, and kidneys were detected by ICP-MS. ICP-MS data at multiple time points indicate that the prodrug is metabolized primarily by the liver and kidneys, with tumor uptake peaking 1 hour after administration (approximately 15 μM), then gradually decreasing, and completely eliminated 48 hours after injection (Figure 5c). Relatively low concentrations of the prodrug in mouse muscle and cerebrum 1 hour after administration explain that the drug does not cause adverse effects in these organs.

[0138] Subsequently, the radiation-mediated release of oxaliplatin in mice and the corresponding therapeutic effects were further evaluated. The average tumor volume was approximately 50 mm². 3HCT116 cells were transplanted into the right flank of Nu / Nu mice until [specific condition]. The mice were randomly divided into seven groups, including a control group (PBS only), a 3 μmol / kg oxaliplatin group, a 30 μmol / kg oxaliPt(IV)-(OAc)2 group, an X-ray group, a 3 μmol / kg oxaliplatin + X-ray group, a 30 μmol / kg oxaliPt(IV)-(OAc)2 + X-ray group, and a 3 μmol / kg transPt(IV)-(OAc)2 + X-ray group, and each group was injected with the drug on day 0 (Figure 5d). The treatment groups were irradiated with 4 Gy of X-rays one hour after injection, and the treatment cycle was repeated on days 10-12. On day 18 after the start of treatment, the tumor size in the control group was 1500 mm. 3 While the tumor growth rate is reached, when 30 μmol / kg of oxaliPt(IV)-(OAc)2 was injected alone, there was no significant effect on tumor growth. However, tumor growth in the 30 μmol / kg oxaliPt(IV)-(OAc)2 + X-ray group was clearly suppressed (Figure 5e, f), and the survival time of the mice was extended (Figure 5g). This explains that the therapeutic effect is due to the release of oxaliplatin mediated by radiation. Furthermore, the mice in the oxaliPt(IV)-(OAc)2 + X-ray treatment group did not experience weight loss (Figure 5h), indicating that our strategy is highly biologically safe. Therefore, the treatment results for HCT116 tumor-bearing mice indicate that this radiation-driven release of Pt(II) drugs is highly feasible in vivo.

[0139] Figure 5 illustrates the use of radiation-driven reduction of the oxaliPt(IV)-(OAc)2 prodrug to release oxaliplatin, enabling a combination of radiotherapy and chemotherapy for oxaliplatin-sensitive HCT116 tumors. The figure shows weight change curves (a) and survival curves (b) for mice intravenously injected with different doses of oxaliPt(IV)-(OAc)2 and oxaliplatin. As evident from studies of drug adaptability in nude mice, the maximum tolerated doses of oxaliplatin and oxaliPt(IV)-(OAc)2 are approximately 3 μmol / kg and 30 μmol / kg, respectively. Figure c shows the pharmacokinetics of the oxaliPt(IV)-(OAc)2 prodrug to determine the optimal timing of radiotherapy. Tumor absorption of the oxaliPt(IV)-(OAc)2 prodrug peaked 1-2 hours after injection and then gradually decreased. Other prodrugs were rapidly removed from the blood and excreted from the body via the renal, hepatic, and biliary systems. d shows the regimen. e-h shows that oxaliplatin was released by radiation to treat tumors (n=6 mice in each group). e shows the tumor volume of a single mouse. f shows the average tumor volume. The prodrug was administered intravenously a total of four times at a dose of 30 μmol / kg. One hour after intravenous injection, 4 Gy of X-rays was irradiated to the tumor site in the irradiation group. The tumor volume in each group was measured every two days and continued for 40 days. g is the survival curve of the mice. In accordance with the guidance of the Peking University Animal Ethics Committee, the tumor volume was 1500 mm³. 3 The mice were killed when the temperature reached a certain level. h is the mouse weight curve. No apparent side effects were observed, highlighting the biosafety of this novel therapeutic strategy.

[0140] This study developed a novel bioshear chemistry to achieve radiation-induced metal reduction in vivo. Applying this strategy to the activation of Pt(IV) prodrugs, and using radiotherapy as an external stimulus to trigger drug release, the release of chemotherapy drugs to tumor sites can be completed under precise radiotherapy guidance. Furthermore, this strategy contributes to solving the problem of radiotherapy resistance in hypoxic tumors, and can even improve drug release efficiency under hypoxic conditions. aq - Inducing direct metal reduction can be extended to other metals or biocomplexes (e.g., metalloproteins), providing an effective tool for analyzing the mechanisms of complex biological processes.

[0141] From the above description, those skilled in the art will readily recognize the essential features of the present invention and can adapt it to various uses and conditions by making various changes and modifications without departing from the spirit and scope of the invention. Therefore, other embodiments are also within the scope of the appended claims.

[0142] This application claims priority to Chinese Patent Application No. 202011337782.X, filed on 25 November 2020, and the contents disclosed in the said Chinese Patent Application are incorporated into this application by reference.

Claims

1. Formula (I), which is activated by radiation and used as a prodrug to treat tumors: 【Chemistry 1】 (In the formula, L １ ~L ６ is a platinum ligand, The complex undergoes L after irradiation. ５ and L ６ Releasing the following equation (II): 【Chemistry 2】 (A Pt(II) complex can be obtained.) A Pt(IV) complex of, The Pt(II) complex of formula (II) is cisplatin, carboplatin, nedaplatin, oxaliplatin, lovaplatin, or heptaplatin, (i) L ５ teeth, － The compound is O-C(O)-R, where R is independently selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and icosyl groups. L ６ teeth, － The structure is O-C(O)-R, where R is independently (dimethylamino)methylene group, 2-(dimethylamino)ethylene group, 3-(dimethylamino)propylene group, 4-(dimethylamino)butylene group, 5-(dimethylamino)pentylene group, 6-(dimethylamino)hexylene group, 3-(4-iodophenyl)propylene group, 3-(3-iodophenyl)propylene group, 3-(3,5-diiodophenyl)propylene group, 3-(4-bromophenyl)propylene group, 3-(3-bromophenyl Selected from the following: (nyl)propylene group, 3-(3,5-dibromophenyl)propylene group, methylamine group, ethylamine group, propylamine group, butylamino group, pentylamino group, hexylamine group, heptylamino group, octylamino group, nonylamino group, decylamino group, undecylamino group, dodecylamino group, tridecylamino group, tetradecanoylamino group, pentadecanoylamino group, hexadecanoylamino group, heptadecylamino group, and octadecanoylamino group; or (ii) L ５ is － O—C(O)—R, where R is independently selected from a carboxymethylene group, a 2-carboxyethylene group, a 3-carboxypropylene group, a 4-carboxybutylene group, a 5-carboxypentylene group, and a 6-carboxyhexylene group, L ６ teeth, － The compound is O-C(O)-R, where R is independently selected from 3-(4-iodophenyl)propylene, 3-(3-iodophenyl)propylene, 3-(3,5-diiodophenyl)propylene, 3-(4-bromophenyl)propylene, 3-(3-bromophenyl)propylene, and 3-(3,5-dibromophenyl)propylene; or (iii) L ５ teeth, － The compound is O-C(O)-R, where R is independently selected from (dimethylamino)methylene, 2-(dimethylamino)ethylene, 3-(dimethylamino)propylene, 4-(dimethylamino)butylene, 5-(dimethylamino)pentylene, and 6-(dimethylamino)hexylene. L ６ teeth, － The compound is O-C(O)-R, where R is independently a methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, 3-(4-iodophenyl)propylene group, 3-(3-iodophenyl)propylene group, 3-(3,5-diiodophenyl)propylene group, or 3-(4-bromophenyl)propylene. Selected from the group, 3-(3-bromophenyl)propylene group, 3-(3,5-dibromophenyl)propylene group, methylamine group, ethylamine group, propylamine group, butylamino group, pentylamino group, hexylamine group, heptylamino group, octylamino group, nonylamino group, decylamino group, undecylamino group, dodecylamino group, tridecylamino group, tetradecanoylamino group, pentadecanoylamino group, hexadecanoylamino group, heptadecylamino group, and octadecanoylamino group. Pt(IV) complex.

2. The Pt(IV) complex according to claim 1, wherein the tumor is leukemia, lung cancer, malignant lymphoma, breast cancer, ovarian cancer, soft tissue sarcoma, osteogenic sarcoma, rhabdomyosarcoma, Ewing's sarcoma, blastoma, neuroblastoma, bladder cancer, thyroid cancer, prostate cancer, head and neck tumor, nasopharyngeal cancer, esophageal cancer, testicular cancer, gastric cancer, liver cancer, pancreatic cancer, cervical cancer, endometrial cancer, melanoma, or colorectal cancer.

3. A pharmaceutical composition comprising the Pt(IV) complex described in claim 1 or 2.

4. A pharmaceutical composition comprising the Pt(IV) complex described in claim 1.

5. A pharmaceutical composition comprising the Pt(IV) complex described in claim 2.

6. A pharmaceutical composition for treating tumors, comprising the Pt(IV) complex according to claim 1 or 2, which is activated by radiation.

7. The pharmaceutical composition according to claim 6, wherein the radiation irradiation is derived from radiotherapy.

8. A Pt(IV) complex according to claim 1 or 2, A kit that includes instructions explaining how to treat the tumor with radiation therapy after administration.

9. The pharmaceutical composition according to claim 3, A kit that includes instructions explaining how to treat the tumor with radiation therapy after administration.

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