A type of inter-astatine [ 211 Preparation methods and applications of At] benzylguanidine

Abstract

The present application provides a kind of interval-astatine 211 The preparation method and application of at] benzyl guanidine relate to the technical field of radiopharmaceutical chemistry. By using a non-toxic boron-containing precursor and a specific copper catalyst system, an electrophilic de-boron astatine reaction is carried out under mild conditions, combined with a tandem purification module and an in-situ elution process of a composite stabilizer, to realize closed, efficient and automated preparation of the whole process. The preparation has excellent anti-radiolysis performance and long-term stability, solving the bottleneck of large precursor toxicity, high temperature and high pressure leading to equipment wear and tear and the inability to transport the preparation over long distances in traditional processes, and is suitable for clinical targeted therapy of tumors with high expression of norepinephrine transporters.

Description

Technical Field

[0001] This invention relates to the field of radiopharmaceutical chemistry, and more specifically, to a meta-astatine [ 211 Preparation method and application of At] benzylguanidine. Background Technology

[0002] Neuroendocrine neoplasms (NENs), such as malignant pheochromocytoma, paraganglioma, and neuroblastoma, are a heterogeneous group of tumors originating from peptidergic neurons and neuroendocrine cells. These tumor cells universally overexpress norepinephrine transporter (NET), providing an ideal molecular target for radionuclide-targeted therapy. Clinically, β-ray-emitting meta-iodine […] 131 I] Benzylguanidine ([ 131 [MIBG] was once the standard radiopharmaceutical for treating unresectable or metastatic diseases of this type. However, 131 I-beta particles have a long physical half-life (8.02 days) and a long range (several millimeters) in tissues, causing most of the radiation energy to escape from micrometastases, resulting in significant radiation damage to normal tissues such as bone marrow. Furthermore, the long half-life and the accompanying gamma rays require prolonged hospitalization and isolation after treatment, greatly increasing medical costs and reducing patients' quality of life.

[0003] In recent years, targeted alpha therapy (TAT) has become a research hotspot in the field of nuclear medicine due to its superior physical and biological properties. (Astatine-211) 211 Alpha-1, as an ideal alpha nuclide, has a suitable physical half-life of 7.2 hours. Its decay-emitted alpha particles exhibit high linear energy transfer (LET) and extremely short range (50-80 micrometers), enabling it to deposit a large amount of energy within tumor cells, inducing DNA double-strand breaks, thereby achieving highly efficient cell killing while significantly reducing damage to surrounding healthy tissues. 211 At markers were developed on the MIBG skeleton for the development of mesenchyme. 211 At] benzylguanidine ([ 211 At]MABG), is considered to be the successor to [ 131 [I] A next-generation therapeutic drug with significant clinical translational value following MIBG.

[0004] although[ 211[At]MABG shows great promise, but its clinical translation faces severe challenges in chemical synthesis and formulation stability. Firstly, astatine (At) is the heaviest element in the halogen group, and the carbon-astatine (C-At) bond has a lower bond energy than the carbon-iodine bond, resulting in poor chemical stability. Early synthetic strategies primarily relied on electrophilic detinification reactions, using tributyltin or trimethyltin precursors. However, organotin compounds exhibit extremely high biotoxicity; even trace residues can lead to severe neurotoxicity and reproductive toxicity. In GMP production, this not only requires cumbersome purification steps to remove heavy metal residues but also necessitates the introduction of expensive inductively coupled plasma mass spectrometry (ICP-MS) for detection, significantly limiting its commercialization.

[0005] To overcome the problem of tin toxicity, subsequent advancements in this field have focused on electrophilic desilication reactions based on arylsilane precursors. While this method eliminates heavy metal toxicity, the silicon-carbon bond dissociation energy is high, typically requiring harsh conditions such as temperatures above 70°C, strong acid environments, and strong oxidizing agents (e.g., N-chlorosuccinimide) for labeling. This is particularly challenging for reagents with a half-life of only 7.2 hours. 211 For At, this not only increases the decay loss of radioactivity, but also poses stringent engineering challenges to the fully automated synthesis module. High temperatures cause solvent vaporization and a sharp increase in internal pressure of the reaction system, which can easily lead to aging, leakage, or even damage to Teflon pipes, solenoid valves, and seals in automated equipment, seriously affecting the service life of the equipment and the reproducibility of batch-to-batch yields.

[0006] Furthermore, the formulation stability of high-activity alpha-nucleoside drugs remains another major technical bottleneck. As clinical trial dosages continue to increase, the stability of high-activity alpha-nucleoside drugs... 211 At in aqueous solution will trigger a violent radiolytic hydrolysis effect, and the large number of hydroxyl radicals and reactive oxygen species generated by the radiolysis of water molecules will rapidly attack […]. 211 The benzylguanidine backbone of the [At]MABG molecule may lead to the breakage of C-At bonds. Existing technologies typically use sodium ascorbate as a single antioxidant, but when faced with continuous bombardment of alpha particles with extremely high LET, the scavenging capacity of a single antioxidant is rapidly depleted, resulting in a significant decrease in radiochemical purity of the product within hours of preparation, which fails to meet the shelf-life requirements for long-distance transportation and clinical use.

[0007] In summary, the existing technology in […] 211 The α-MABG preparation technology faces inherent contradictions in terms of the safety of chemical precursors, compatibility with automated processes, and long-term stability of formulations. Therefore, there is an urgent need to develop an automated synthesis method and formulation composition that utilizes non-toxic precursors, operates efficiently under mild conditions, and is resistant to high-activity α-ray radiation decomposition, in order to advance this drug from laboratory research to clinical commercial application. Summary of the Invention

[0008] To overcome the shortcomings of the prior art, the present invention provides an inter-astatine [ 211 The preparation method and application of At] benzylguanidine are proposed to solve the bottleneck problems in existing astatine labeling processes, such as high precursor toxicity, equipment damage caused by high temperature and high pressure, inability of single stabilizers to resist high-activity alpha-ray radiation hydrolysis, short shelf life of formulations, and inability to achieve long-distance cold chain distribution.

[0009] The first aspect of the present invention provides an inter-astatine [ 211 The preparation method of [At] benzylguanidine specifically includes the following steps: Step S1: The solution containing astatine-211 is mixed with a boron-containing precursor compound and a copper catalyst in a solvent, and then electrophilic deboronization astatine reaction is carried out to obtain a mixed solution. Step S2: The mixture obtained in step S1 is separated by a purification module, which includes at least a cation exchange unit and a reversed-phase chromatography unit; the purification module is rinsed with a washing solution to retain the copper catalyst and remove free astatine ion impurities, so that the generated meta-astatine [ 211 At] benzylguanidine remains on the reversed-phase chromatography unit; Step S3: Elute the meta-astatine on the reversed-phase chromatography unit using a pharmaceutical eluent pre-contained with a composite stabilizer. 211 At] benzylguanidine, after collection, yields meso-astatine [ 211 At] benzylguanidine.

[0010] Compared with existing technologies, this invention achieves seamless integration of labeling reaction and formulation by constructing a closed-loop process of "electrophilic deboratinization-binary purification-online formulation". This approach not only completely eliminates the time-consuming and radioactive aerosol-evaporizing organic solvent heating step in traditional processes, but also drastically reduces the overall synthesis time to less than 15 minutes, minimizing the impact on [the process's overall efficiency]. 211 At activity decays due to its half-life; meanwhile, by directly eluting with an eluent pre-dissolved in a complex stabilizer, a directly injectable final product can be obtained in one step, significantly improving the cost-effectiveness and radiation safety of clinical translation.

[0011] In one possible implementation, step S1 is carried out under closed conditions, and the boron-containing precursor compound is m-benzylguanidine arylboronic acid or its borate ester derivative. The copper catalyst is a copper trifluoromethanesulfonate complex containing nitrogen-containing heterocyclic ligands; The parameters for the electrophilic deboronization reaction are as follows: temperature 20-50℃, time 5-20min; The reaction solvent is selected from methanol, ethanol, acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, or any mixture thereof with water.

[0012] To address the issues of highly toxic organotin precursors and the need for high-temperature activation of silicon precursors in existing technologies, this invention introduces a safe and mild labeling chemical system. By employing m-benzylguanidine arylboronic acid or its borate derivatives as a non-heavy metal precursor, and combining it with a copper catalyst containing nitrogen-containing heterocyclic ligands, this invention eliminates the risk of heavy metal toxicity and the subsequent cumbersome ICP-MS quality control requirements at the source. This system can efficiently activate carbon-boron bonds under mild conditions of 20-50°C, avoiding guanidine thermal degradation caused by high temperatures, achieving a high radiochemical yield of over 85%, and significantly reducing production costs and compliance thresholds.

[0013] In one possible implementation, the boron-containing precursor compound is pinacol ester of m-benzylguanidine phenylboronic acid; The copper catalyst is copper tetrapyridine trifluoromethanesulfonate; The parameters for the electrophilic deboronization reaction are as follows: temperature 35-45℃, time 8-12min; The reaction solvent is a mixture of methanol and water in a volume ratio of (1-4):1 or a mixture of acetonitrile and water in a volume ratio of (1-4):1.

[0014] To further optimize catalytic efficiency and process robustness, this invention finely controls the key parameters of the reaction system. Using tetrapyridine-copper trifluoromethanesulfonate as a specific catalyst, combined with the MABG-BPin precursor and a specific ratio of alcohol / water mixed solvent, the electrophilic deboronization reaction reaches optimal equilibrium in just 8-12 minutes within a near-room temperature range of 35-45°C. This "micro-thermal" condition effectively suppresses side reactions, ensures extremely high batch-to-batch reproducibility, and significantly reduces the thermal load and pipeline pressure on the automated synthesizer, providing a guarantee for high-frequency GMP production.

[0015] In one possible implementation, in step S2, the cation exchange unit and the reversed-phase chromatography unit are connected in series, and the cation exchange unit is a sulfonic acid type cation exchange column, and the reversed-phase chromatography unit is a C18 reversed-phase chromatography column. The cleaning solution is ultrapure water or a weak acid aqueous solution with a concentration of 0.01-0.1%.

[0016] To address the issue of non-target organ radiotoxicity caused by free astatine, this invention designs a highly efficient online purification module. By employing a tandem system of a sulfonic acid cation exchange column and a C18 reversed-phase column, the ion exchange mechanism strongly retains free astatine ions and the copper catalyst, ensuring that impurities are completely discharged with the waste liquid, while the target product is tightly retained on the C18 column. Combined with washing with a 0.01-0.1% weak acid aqueous solution, this strategy eliminates the risk of radiation exposure to normal organs such as the thyroid gland at the source, significantly improving the safety of clinical drug use.

[0017] In one possible implementation, in step S3, the pharmaceutical eluent comprises the following components: First stabilizer: ascorbic acid or a pharmaceutically acceptable salt thereof; Second stabilizer: selected from gentianic acid, a pharmaceutically acceptable salt of gentianic acid, or nicotinamide; Pharmaceutical carrier: selected from water for injection or 0.9% sodium chloride injection; Pharmaceutically acceptable solubilizer; The pH value of the pharmaceutical eluent is weakly acidic.

[0018] To address the challenge of severe radioactive hydrolysis caused by high-activity alpha nuclides, this invention aims to construct a composite stabilizer system with synergistic antioxidant effects. By introducing a combination of ascorbic acid (first stabilizer) and gentian acid / nicotinamide (second stabilizer) into the pharmaceutical eluent, and utilizing a weakly acidic pH environment, this invention provides […]. 211 At]MABG provides a comprehensive free radical scavenging barrier. This formulation is designed to not only rapidly quench primary radioactive radicals but also continuously inhibit secondary oxidative stress through a cascade reaction, fundamentally solving the stability crisis of high-activity formulations during storage.

[0019] In one possible implementation, the concentration of the first stabilizer is 0.5 g / 100 ml to 5.0 g / 100 ml; The concentration of the second stabilizer is 0.01 g / 100 ml to 0.5 g / 100 ml; The co-solvent is ethanol, with a volume fraction of 1-10%; The remainder is water for injection containing pH buffer or 0.9% sodium chloride injection containing pH buffer; The pH value of the pharmaceutical eluent is 4.0-6.0.

[0020] Based on an in-depth study of the synergistic mechanism of the composite stabilizer, this invention optimizes the specific ratio and buffer system of the eluent. By controlling sodium ascorbate at 0.5-5.0 g / 100 mL and sodium gentianate at 0.01-0.5 g / 100 mL, and supplementing with 1-10% ethanol for solubilization and a buffer salt system with a pH of 4.0-6.0, the formulation can maintain a radiochemical purity of over 95% for 48-72 hours even under extreme high-activity conditions of 1 GBq / mL. This unexpected technical effect successfully overcomes the industrialization bottleneck of long-distance cold chain distribution of radiopharmaceuticals across regions and has significant commercial value.

[0021] A second objective of this invention is to provide an automated synthesis cartridge for the aforementioned preparation method, comprising: A reaction reservoir assembly pre-loaded with a solution of the precursor compound and a solution of the copper catalyst; An eluent reservoir pre-loaded with the pharmaceutical eluent; The purification module includes a sulfonic acid cation exchange column and a C18 reversed-phase chromatography column connected in series. The liquid transfer system, with its tubing made of polyetheretherketone or medical-grade polypropylene, is used to connect the reaction reservoir assembly, the purification module, and the finished product collection bottle under automated program control. The finished product collection bottle is equipped with a radioactive-grade sterile filter at its inlet.

[0022] To perfectly adapt to the aforementioned mild synthesis process, this invention also provides a dedicated automated synthesis cartridge. Thanks to the reduced reaction temperature, the cartridge's liquid circuit system can utilize cost-effective and biocompatible PEEK or medical-grade PP tubing, completely replacing the expensive high-temperature, high-pressure resistant Teflon tubing. This structural design not only eliminates the risks of seal aging and leakage caused by high temperature and pressure, but also achieves "plug-and-play" standardized GMP production by pre-loading various reaction reagents and composite stabilizers, greatly extending the service life and operational safety of automated equipment.

[0023] The third object of the present invention is to provide an inter-astatine [ 211 At] benzylguanine radiopharmaceutical formulation composition, comprising: Inter-astatine [ 211 At] benzylguanidine, the meso-astatine [ 211 At] benzylguanidine in the meso-astatine [ 211 The radioactivity concentration in the [At] benzylguanidine radiopharmaceutical formulation composition is 50 MBq / mL-2000 MBq / mL; First stabilizer: ascorbic acid or a pharmaceutically acceptable salt thereof; Second stabilizer: selected from gentianic acid, a pharmaceutically acceptable salt of gentianic acid, or nicotinamide; Pharmaceutical carrier.

[0024] This invention ultimately provides a highly stable [ 211 [AT]MABG radiopharmaceutical formulation composition. This formulation combines a therapeutically effective amount of the targeting molecule with a specific concentration of dual-compound stabilizers, exhibiting excellent resistance to radiodegradation across a wide activity range of 50 MBq / mL to 2000 MBq / mL. Compared to traditional single-stabilizer systems, this composition shows significantly improved radiochemical purity at the end of its shelf life, ensuring the efficacy and safety of the drug during clinical administration, and is a key carrier for the practical application of targeted alpha therapy.

[0025] The fourth object of the present invention is to provide an inter-astatine [211 Application of At] benzylguanine radiopharmaceutical formulation composition in the preparation of a tumor drug for treating tumors with high expression of norepinephrine transporters.

[0026] Based on the excellent targeted killing ability and safety of the above-mentioned formulation composition, this invention establishes its use in the preparation of drugs for treating tumors that highly express norepinephrine transporter (NET). For refractory neuroendocrine tumors such as malignant pheochromocytoma, paraganglioma, and neuroblastoma, this drug can utilize the extremely high linear energy transfer properties of alpha particles to induce irreparable double-strand breaks in cancer cell DNA within tiny lesions, while simultaneously maximally protecting surrounding healthy tissue with its extremely short range, providing patients with a revolutionary new option for precision treatment.

[0027] Compared with the prior art, the present invention has the following advantages: 1. Mild chemical system, eliminating the risks of heavy metal toxicity and thermal degradation. This invention uses m-benzylguanidine arylboronic acid or its borate ester derivatives as a boron-containing precursor, completely eliminating the need for traditional highly toxic trialkyltin compounds. This not only eradicates the risk of highly neurotoxic heavy metal residues at the source, but also eliminates the need for costly inductively coupled plasma mass spectrometry (ICP-MS) for trace tin detection in the final product quality control, significantly lowering the GMP compliance threshold. Simultaneously, the efficient activation of the carbon-boron bond by a copper catalyst with nitrogen-containing heterocyclic ligands allows the reaction to rapidly reach equilibrium at near-room temperature (20℃-50℃), effectively avoiding high-temperature-induced MABG guanidine thermal degradation and achieving a decay-corrected radiochemical yield of over 85% within 5-20 minutes.

[0028] 2. Align with automation engineering to enhance the robustness of large-scale production. Compared to the risks of solvent vaporization and high system pressure caused by conventional high-temperature processes, the mild system of this invention keeps the synthesizer's internal pressure at a consistently low safety baseline, significantly reducing the risk of mechanical fatigue and aging leakage from Teflon solenoid valves and seals. Thanks to this, disposable synthesis cartridges no longer require expensive high-temperature resistant tubing; instead, they can utilize biocompatible and cost-effective polyetheretherketone (PEEK) or medical-grade polypropylene (PP) tubing. This improvement not only extends the lifespan of automated equipment but also reduces non-specific adsorption of astatine on high-temperature tubing walls, significantly improving final product yield and batch-to-batch reproducibility.

[0029] 3. A complex antioxidant system overcomes the bottleneck in the transport of high-dose alpha nuclides. To address the severe radiolytic hydrolysis effect induced by high-activity alpha particles, this invention breaks through the traditional limitations of single ascorbate salts and pioneers a composite stabilizer formulation of "ascorbic acid + gentianic acid / nicotinamide". Through a cascade quenching and synergistic regeneration mechanism between substances with different redox potentials, the chain reaction of hydroxyl radicals is effectively blocked. Experiments have shown that after being placed at high activity (1 GBq / mL) and room temperature for 48 hours, the finished solution using this formulation maintains a stable radiochemical purity (RCP) of over 95%, completely solving the problem of degradation within 24 hours in existing technologies and overcoming the industrialization bottleneck of long-distance cold chain distribution across regions.

[0030] 4. Integrated online process, comprehensively improving clinical cost-effectiveness. The "cation exchange + reversed-phase chromatography" dual purification module designed in this invention can completely retain free astatine ions and copper catalysts, eliminating the accumulation and toxicity of free astatine in non-target organs such as the thyroid gland and gastric mucosa from the source. More importantly, by directly eluting with a pharmaceutical eluent pre-dissolved with a composite stabilizer, purification and formulation are completed in one step, completely eliminating the time-consuming heating and evaporation steps in traditional processes that easily lead to aerosol loss. This integrated process drastically reduces purification time from the traditional 40-60 minutes to less than 15 minutes, based on... 211 With a half-life of only 7.2 hours, this shortening provides crucial support for salvaging effective radiation doses and improving the cost-effectiveness of clinical treatment. Detailed Implementation

[0031] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the claims of the present invention.

[0032] It should be noted that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0033] Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In some instances, terms having a conventional meaning are defined herein for clarification or ease of reference, and such definitions should not be construed as indicating a significant difference from conventional understanding in the art. The technical methods described or referenced herein are generally well understood by those skilled in the art and employed by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents, and instruments shall be performed according to the manufacturer's instructions and parameters.

[0034] This specific embodiment discloses a method for preparing the key precursor compound, m-benzylguanidine phenylboronic acid pinacol ester, which specifically includes the following steps: (1) Dissolve 1.0 mmol of 3-aminomethylphenylboronic acid pinacol ester in anhydrous N,N-dimethylformamide (DMF, 5 mL), add triethylamine (TEA, 2.5 mmol) as an acid-binding agent, and stir until homogeneous; (2) Slowly add 1.2 mmol of 1,3-bis-Boc-2-(trifluoromethylsulfonyl)guanidine DMF solution to the above solution; (3) Stir the reaction continuously at room temperature for 12 hours. Monitor the reaction progress by thin-layer chromatography (TLC). After the raw materials are consumed, add an appropriate amount of pure water to quench the reaction. (4) The reaction mixture was extracted three times with ethyl acetate (EtOAc), 15 mL each time. The organic phases were combined, dried over anhydrous sodium sulfate, and concentrated by rotary evaporation. (5) The concentrate was purified by silica gel column chromatography with petroleum ether / ethyl acetate gradient elution. The target fraction was collected and dried under vacuum to obtain the Boc-protected intermediate. (6) The above intermediate was placed in a dichloromethane (DCM) solution containing 20% ​​trifluoroacetic acid (TFA) to remove the Boc protecting group, and reacted at room temperature for 2 hours. After the reaction was completed, the mixture was dried under nitrogen and washed with a small amount of ice-cold ether to finally obtain the precursor compound MABG-BPin as a white solid powder, with a yield of about 70%-80%. This precursor compound can be stored stably for a long time under dry, light-protected conditions at -20°C, and can be used as a standard raw material for subsequent automated synthesis.

[0035] The following examples further illustrate this point.

[0036] Example 1 This embodiment provides a [ 211 The automated synthesis method for MABG uses a pre-filled automated synthesis cartridge, and the specific steps are as follows: 1. Card box pre-loading preparation (preparation before synthesis): Reaction site A (precursor solution): Prepare the key precursor compound m-benzylguanidine phenylboronic acid pinacol ester according to the method disclosed in the specific implementation method. Accurately weigh 1.0 μmol of m-benzylguanidine phenylboronic acid pinacol ester, dissolve it in 200 μL of methanol, filter it aseptically, and then put it into the storage tube A. Reaction site B (catalyst solution): Accurately weigh 2.0 μmol of tetrapyridine trifluoromethanesulfonate copper, dissolve it in 100 μL of acetonitrile, filter it aseptically, and then put it into storage tube B; Elution site C (composite stable eluent): Prepare 2.0 mL of 0.9% sodium chloride injection containing 10% (v / v) ethanol, 2.5% (w / v) sodium ascorbate and 0.1% (w / v) sodium gentianate. Adjust the pH to 5.0 using a pH buffer, filter the solution through a 0.22 μm aqueous filter membrane for sterilization, and then place it into the eluent reservoir C.

[0037] Purification column configuration: The cartridge contains pre-installed purification column components connected in series, with an upstream sulfonic acid cation exchange column (MCX column, i.e., cation exchange unit) and a downstream C18 reversed-phase solid-phase extraction (SPE) short column (i.e., reversed-phase chromatography unit).

[0038] The tubing of the liquid transfer system is made of polyetheretherketone (PEEK), and the connecting parts are all made of medical-grade polypropylene (PP) to ensure no leaching or leakage under mild reaction conditions.

[0039] 2. Automated synthesis operation steps: Step S1, Labeling Reaction (Active Material Acceptance and Mild Astatification): Produced by a cyclotron and extracted by dry distillation. 211 An At solution (approximately 1000 MBq) was dissolved in a small amount of methanol / water mixed solvent and automatically drawn into the main reaction tube of the synthesizer under negative pressure. The program controlled the sequential opening of valves A and B at reaction positions, automatically pumping 200 μL of the precursor solution and 100 μL of the catalyst solution into the main reaction tube. The synthesizer maintained the reaction tube at a constant temperature of 40°C, keeping the mixture mixed by slow bubble bubbling or magnetic stirring, and continued the reaction for 10 minutes to complete the electrophilic deboronization reaction.

[0040] Step S2, Purification and Separation (Online Adsorption and Impurity Removal): After the reaction is complete, 5 mL of ultrapure water is added under program control to dilute the reaction solution. The diluted solution is then slowly pushed through a series of MCX and C18 columns at a set flow rate under positive pressure. During this process, unreacted copper catalyst and metal ions are retained by the MCX column, while free... 211 At - Polar impurities are discharged with the waste liquid into the shielded waste liquid collection bottle, while the target product [ 211At]MABG adhered tightly to the C18 column. Subsequently, the C18 column was rinsed with 10 mL of pure water and purged with sterile nitrogen for 1 minute to remove residual moisture.

[0041] Step S3, Formulation Collection (Integrated Elution and Stabilization Formulation): Start the valve at elution position C and push 2.0 mL of pre-loaded "composite stabilized eluent" through the C18 column at a uniform rate. 211 [At]MABG flows out with the eluent, passes through a 0.22μm radioactive-grade sterile filter at the terminal, and is directly dripped into a pre-vacuumed finished vial to obtain a directly injectable [At]MABG. 211 At]MABG radiopharmaceutical preparation.

[0042] 3. Effect detection: Process stability: The entire automated process takes approximately 22-25 minutes. During the synthesis process, the system pressure remains within the normal range, and no deformation or leakage occurs in the pipelines or solenoid valves.

[0043] Yield and Purity: The decay-corrected radiochemical yield remained stable at 88%-92%. Radio-HPLC analysis showed that the radiochemical purity (RCP) of the finished product was >99.5%, and the free astatine residue was <0.2%.

[0044] Safety and Compliance: Ethanol residue levels are controlled within clinically safe limits. Due to the use of non-tin / non-silicon precursors and a composite stabilizer system, the finished product does not require testing for toxic heavy metals (such as tin), meeting the requirements of GMP's simplified quality control process.

[0045] Example 2 This embodiment provides a [ 211 The automated synthesis method for At]MABG specifically includes: 1. Card box pre-loading preparation (preparation before synthesis): Reaction site A (precursor solution): Accurately weigh 1.0 μmol of m-benzylguanidine phenylboronic acid, dissolve it in 200 μL of acetonitrile / water mixed solvent, filter it aseptically, and then put it into storage tube A.

[0046] Reaction site B (catalyst solution): Accurately weigh 2.0 μmol of copper 2,2'-bipyridine trifluoromethanesulfonate, dissolve it in 100 μL of acetonitrile, filter it aseptically, and then put it into storage tube B.

[0047] Elution site C (composite stable eluent): Prepare 2.0 mL of 0.9% sodium chloride injection containing 10% (v / v) ethanol, 2.5% (w / v) sodium ascorbate and 0.1% (w / v) sodium gentianate. Adjust the pH to 5.0 using buffer salts, filter the solution through a 0.22 μm aqueous filter membrane for sterilization, and then load it into the eluent reservoir C.

[0048] Purification column configuration and materials: The cartridge contains pre-assembled purification column assemblies connected in series. The upstream component is a sulfonic acid cation exchange column (MCX column, i.e., cation exchange unit), and the downstream component is a C18 reversed-phase solid-phase extraction (SPE) short column (i.e., reversed-phase chromatography unit). The tubing of the liquid transfer system is made of polyetheretherketone (PEEK), and all connecting parts are made of medical-grade polypropylene (PP) to ensure no dissolution and no leakage under mild reaction conditions.

[0049] 2. Automated synthesis operation steps: S1 labeling reaction (mild astatinization, validating a wide and preferred range): Cyclotron-produced and extracted by dry distillation. 211 An At solution (approximately 1000 MBq) was dissolved in a small amount of acetonitrile / water mixed solvent and automatically drawn into the main reaction tube of the synthesizer under negative pressure. The program controlled the sequential opening of valves A and B at reaction positions, automatically pumping 200 μL of the precursor solution and 100 μL of the catalyst solution into the main reaction tube. The synthesizer maintained the reaction tube at a constant temperature of 35°C, keeping the mixture mixed by slow bubble bubbling or magnetic stirring for 8 minutes to complete the electrophilic deboronization reaction.

[0050] S2 Purification and Separation (Online Adsorption and Impurity Removal): After the reaction, 5 mL of ultrapure water is added under program control to dilute the reaction solution, and the diluent is slowly pushed through the MCX and C18 columns connected in series at a set flow rate under positive pressure. During this process, unreacted copper catalyst and metal ions are retained by the MCX column, while free... 211 At - Polar impurities are discharged with the waste liquid into the shielded waste liquid collection bottle, while the target product [ 211 At]MABG adhered tightly to the C18 column. Subsequently, the C18 column was rinsed with 10 mL of pure water and purged with sterile nitrogen for 1 minute to remove residual moisture.

[0051] S3 Formulation Collection (Integrated Elution and Stabilization Formulation): Activate the valve at elution position C to push 2.0 mL of pre-loaded "composite stabilized eluent" through the C18 column at a uniform rate. 211 [At]MABG flows out with the eluent, passes through a 0.22μm radioactive-grade sterile filter at the terminal, and is directly dripped into a pre-vacuumed finished vial to obtain a directly injectable [At]MABG. 211At]MABG radiopharmaceutical preparation.

[0052] Example 3 This embodiment provides a [ 211 The automated synthesis method for At]MABG is as follows: 1. Card box pre-loading preparation (preparation before synthesis): Reaction site A (precursor solution): Accurately weigh 1.0 μmol of MABG-BPin, dissolve it in 200 μL of methanol, filter it aseptically, and then put it into storage tube A.

[0053] Reaction site B (catalyst solution): Accurately weigh 2.0 μmol of tetrapyridine trifluoromethanesulfonate copper, dissolve it in 100 μL of acetonitrile, filter it aseptically, and then put it into storage tube B.

[0054] Elution site C (composite stable eluent): Prepare 2.0 mL of 0.9% sodium chloride injection containing 1% (v / v) ethanol, 0.5% (w / v) sodium ascorbate and 0.01% (w / v) sodium gentianate. Adjust the pH to 4.0 using buffer salts, filter the solution through a 0.22 μm aqueous filter membrane for sterilization, and then load it into the eluent reservoir C.

[0055] Purification column configuration and materials: Same as in Example 2, except that the tubing material is PEEK and the connectors are made of PP.

[0056] 2. Automated synthesis operation steps: S1 labeling reaction: produced by cyclotron and extracted by dry distillation. 211 An At solution (with feed activity increased to 2.2 GBq) was dissolved in a small amount of methanol / water mixed solvent and automatically drawn into the main reaction tube of the synthesizer under negative pressure. The precursor and catalyst solutions were sequentially pumped in under program control, and the reaction was carried out at a constant temperature of 45°C for 10 min.

[0057] S2 Purification and Separation: After the reaction, dilute with 5 mL of ultrapure water and push through a tandem column under positive pressure. Rinse the C18 column with 10 mL of 0.01% (w / v) acetic acid aqueous solution, then purge with sterile nitrogen for 1 minute.

[0058] S3 Formulation Collection: Start elution at position C, push 2.0 mL of the composite stable eluent through the C18 column, and collect it in the finished vial after sterile filtration.

[0059] Comparative Example 1 This embodiment provides a [ 211The automated synthesis method for At]MABG uses a pre-filled automated synthesis cartridge. The only difference from Example 1 is that in the labeling reaction of step S1 in this example, the reaction conditions are room temperature and the reaction time is 15 min. The rest is the same as in Example 1, and will not be repeated here.

[0060] Comparative Example 2 This comparative example reproduces a typical silicon precursor synthesis route in the prior art, as follows: 1. Pre-loading of cartridges and preparation of reagents: Reaction site A (silicon precursor solution): Accurately weigh 10 mg of silicon precursor mTMSBG, dissolve it in 200 μL of acetonitrile, filter it aseptically, and then put it into storage tube A.

[0061] Activator solution: Accurately weigh 5.0 mg of N-chlorosuccinimide (NCS) and 10 μL of trifluoroacetic acid (TFA), dissolve them in 100 μL of acetonitrile, filter aseptically, and then put them into storage tube B.

[0062] Cleaning solution and eluent: The same 0.05% acetic acid aqueous solution as in Example 1 of this invention was used as the cleaning solution, and physiological saline (without composite stabilizer) was used as the eluent.

[0063] 2. Automated synthesis operation steps: Step S1, Labeling Reaction (High Temperature Strong Acid Activation): Take a sample containing approximately 1.2 GBq... 211 The At solution was introduced into the reaction tube. The valves of reservoirs A and B were opened under program control, and the mTMSBG solution and NCS / TFA activator solution were pumped in sequentially. The synthesizer controlled the reaction tube to heat to 70°C and maintained the temperature for 10 minutes.

[0064] Step S2, Purification and Separation: After the reaction, add 5 mL of ultrapure water for dilution, and push under positive pressure through a series of MCX and C18 columns. Free astatine and catalyst remain in the waste liquid. 211 At]MABG is adsorbed on a C18 column.

[0065] Step S3, Elution and Collection: Elute the C18 column with physiological saline and collect the finished product through a sterile filter.

[0066] Furthermore, this application investigated the protective capabilities of different stabilizer formulations against high-intensity radiative hydrolysis generated by extremely high linear energy transfer (LET) alpha rays.

[0067] 1. Formulation preparation and grouping: Prepared according to the automated synthesis method of Example 2 [ 211At]MABG, adjust the initial feed activity so that the radioactivity concentration in the final collected 2 mL of finished solution reaches the set high level. Dispense the resulting finished solution and prepare formulations for the following three different stabilizer systems: Prescription A (blank control): The eluent was 0.9% sodium chloride injection containing 10% ethanol, with no additional antioxidants added.

[0068] Prescription B (Single Stabilizer Control): The eluent contains only a single antioxidant, namely 2.5% (w / v) sodium ascorbate.

[0069] Formula C (compound stabilizer of the present invention): A compound antioxidant system is added to the eluent, namely 2.5% (w / v) sodium ascorbate + 0.1% (w / v) sodium gentianate.

[0070] 2. Stability testing: The three groups of samples were stored at room temperature in the dark. Samples were taken at 0 hours (initial), 24 hours, 48 ​​hours and 72 hours, and their radiochemical purity (RCP) was determined by Radio-HPLC.

[0071] 3. Results and Data Analysis: The test results showed that, under extreme alpha radiation conditions with extremely high radioactivity, the samples in each group exhibited significantly different levels of stability: Formula A, lacking free radical scavenging ability, underwent severe radiation hydrolysis, and the products rapidly degraded.

[0072] Prescription B uses a single sodium ascorbate system, which can effectively consume hydroxyl radicals in the early stages. However, as time goes on, the antioxidants are gradually depleted under continuous high-intensity irradiation, causing the radiochemical purity to drop below the clinically acceptable threshold of 90% after 24 hours, which cannot meet the requirements for medication after long-distance transportation.

[0073] Formula C exhibited unexpected technical effects. The unique "sodium ascorbate + sodium gentianate" composite stabilizer formulation of this invention, through the cascade synergistic effect of their redox potentials, forms a cyclical protective network capable of continuously "absorbing-transferring-quenching" secondary free radicals and chelating trace catalytic metals. Even after 72 hours, its radiochemical purity remained stable at over 95%.

[0074] 4. Conclusion: This embodiment demonstrates the superior anti-radiation hydrolysis capability of the composite stabilizer formulation at extremely high activity, completely breaking through the barrier of traditional radiopharmaceuticals that can only be "prepared and used immediately," thus providing a basis for […]. 211 At]MABG provides crucial support for the commercial application of long-distance cold chain / ambient temperature logistics distribution across regions.

[0075] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A type of inter-astatine [ 211 The preparation method of At] benzylguanidine, characterized in that, The preparation method specifically includes the following steps: Step S1: The solution containing astatine-211 is mixed with a boron-containing precursor compound and a copper catalyst in a solvent, and then electrophilic deboronization astatine reaction is carried out to obtain a mixed solution. Step S2: The mixture obtained in step S1 is separated by a purification module, which includes at least a cation exchange unit and a reversed-phase chromatography unit; the purification module is rinsed with a washing solution to retain the copper catalyst and remove free astatine ion impurities, so that the generated meta-astatine [ 211 At] benzylguanidine remains on the reversed-phase chromatography unit; Step S3: Elute the meta-astatine on the reversed-phase chromatography unit using a pharmaceutical eluent pre-contained with a composite stabilizer. 211 At] benzylguanidine, after collection, yields meso-astatine [ 211 At] benzylguanidine.

2. The preparation method according to claim 1, characterized in that, Step S1 is carried out under closed conditions, and the boron-containing precursor compound is m-benzylguanidine arylboronic acid or its boron ester derivative. The copper catalyst is a copper trifluoromethanesulfonate complex containing nitrogen-containing heterocyclic ligands; The parameters for the electrophilic deboronization reaction are as follows: temperature 20-50℃, time 5-20min; The reaction solvent is selected from methanol, ethanol, acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, or any mixture thereof with water.

3. The preparation method according to claim 1, characterized in that, The boron-containing precursor compound is pinacol ester of m-benzylguanidine phenylboronic acid; The copper catalyst is copper tetrapyridine trifluoromethanesulfonate; The parameters for the electrophilic deboronization reaction are as follows: temperature 35-45℃, time 8-12min; The reaction solvent is a mixture of methanol and water in a volume ratio of (1-4):1 or a mixture of acetonitrile and water in a volume ratio of (1-4):

1.

4. The preparation method according to claim 1, characterized in that, In step S2, the cation exchange unit and the reversed-phase chromatography unit are connected in series, and the cation exchange unit is a sulfonic acid type cation exchange column, and the reversed-phase chromatography unit is a C18 reversed-phase chromatography column. The cleaning solution is ultrapure water or a weak acid aqueous solution with a concentration of 0.01-0.1%.

5. The preparation method according to claim 1, characterized in that, In step S3, the pharmaceutical eluent comprises the following components: First stabilizer: ascorbic acid or a pharmaceutically acceptable salt thereof; Second stabilizer: selected from gentianic acid, a pharmaceutically acceptable salt of gentianic acid, or nicotinamide; Pharmaceutical carrier: selected from water for injection or 0.9% sodium chloride injection; Pharmaceutically acceptable solubilizer; The pH value of the pharmaceutical eluent is weakly acidic.

6. The preparation method according to claim 5, characterized in that, The concentration of the first stabilizer is 0.5 g / 100 ml to 5.0 g / 100 ml; The concentration of the second stabilizer is 0.01 g / 100 ml to 0.5 g / 100 ml; The co-solvent is ethanol, with a volume fraction of 1-10%; The remainder is water for injection containing pH buffer or 0.9% sodium chloride injection containing pH buffer; The pH value of the pharmaceutical eluent is 4.0-6.

0.

7. An automated synthesis cartridge for implementing the preparation method according to any one of claims 1-6, characterized in that, include: A reaction reservoir assembly pre-loaded with a solution of the precursor compound and a solution of the copper catalyst; An eluent reservoir pre-loaded with the pharmaceutical eluent; The purification module includes a sulfonic acid cation exchange column and a C18 reversed-phase chromatography column connected in series. The liquid transfer system, with its tubing made of polyetheretherketone or medical-grade polypropylene, is used to connect the reaction reservoir assembly, the purification module, and the finished product collection bottle under automated program control. The finished product collection bottle is equipped with a radioactive-grade sterile filter at its inlet.

8. A type of inter-astatine [ 211 At] benzylguanidine radiopharmaceutical formulation composition, characterized in that include: The inter-astatine [ prepared by any of the methods of claims 1-6] 211 At] benzylguanidine, the meso-astatine [ 211 At] benzylguanidine in the meso-astatine [ 211 The radioactivity concentration in the [At] benzylguanidine radiopharmaceutical formulation composition is 50 MBq / mL-2000 MBq / mL; First stabilizer: ascorbic acid or a pharmaceutically acceptable salt thereof; Second stabilizer: selected from gentianic acid, a pharmaceutically acceptable salt of gentianic acid, or nicotinamide; Pharmaceutical carrier.