Radioactive targeting nuclide drug molecule design method based on first principle

Abstract

The invention relates to the technical field of radiopharmaceutical research and development, and discloses a radiotargeted nuclide drug molecule design method based on a first principle, comprising: screening a high-specificity target based on a preset demand, and screening candidate nuclides according to drug functions and ligand types corresponding to the high-specificity target; the method comprises the following steps: setting a difunctional chelating agent adaptive to candidate nuclides, setting a ligand for a high-specificity target, setting a linker for connecting the difunctional chelating agent and the ligand, calculating and optimizing the difunctional chelating agent, the ligand and the linker according to a first principle, and assembling according to a nuclide-chelating agent-linker-ligand sequence to obtain an initial molecular complex; and for alpha nuclide in the initial molecular complex, calculating and optimizing through a first principle to obtain a target molecular complex. According to the method, by constructing collaborative design logic, the drug targeting property, stability and the balance capacity of the curative effect and safety are improved, special optimization is carried out for alpha nuclide risks so as to reduce toxicity, and extensive expandability is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radiopharmaceutical research and development, in particular to a first-principle-based radiopharmaceutical molecular design method. BACKGROUND

[0002] Radiopharmaceuticals are the core means of precise diagnosis and treatment in nuclear medicine, and their design needs to consider target specificity, radionuclide adaptability, chelator stability, ligand affinity, and the pharmacokinetic regulation ability of the linker to achieve efficient enrichment of the drug in diseased tissues and low toxicity in normal tissues.

[0003] In the prior art, the development of such drugs relies on traditional experimental trial-and-error methods, which has significant limitations: first, the optimization of target-ligand binding lacks microscopic mechanism analysis at the atomic / electronic level, and it is difficult to ensure binding specificity through in vitro screening, which can easily lead to off-target binding of the drug; second, the matching of radionuclide selection and ligand characteristics is insufficient, and there is no systematic correlation between radionuclide physical properties and ligand in vivo retention rules, often leading to insufficient efficacy or increased toxicity due to mismatched half-life; third, the design of chelators lacks consideration of the decay characteristics of special radionuclides (such as alpha radionuclides), making it difficult to address the radionuclide dissociation problem caused by the decay recoil effect, increasing the risk of radiation to normal tissues; fourth, the pharmacokinetic regulation of the linker lacks precise design, and it is difficult to effectively balance the retention of the drug in target tissues and the clearance of the drug in non-target tissues; in addition, existing solutions focus on single-element optimization and lack a collaborative design logic, making it difficult to balance the targeting, stability, and safety of the drug.

[0004] Currently, in the development of radiopharmaceuticals in China, the production and basic data accumulation of general radionuclides (such as 68Ga, 177Lu, 99Tcᵐ) have been achieved, but the large-scale production process of alpha radionuclides such as 225Ac and 223Ra is still being explored; the development of advanced chelators such as Macropa and some high-affinity ligands is still in the catch-up stage, and relevant clinical data are also lacking. Therefore, there is an urgent need for a design method based on microscopic calculation, covering multiple-element collaboration, and adapting to the current research and development situation in China, to address the low efficiency, inaccurate optimization, and poor multi-element collaboration of existing technologies, and to promote the efficient development of radiopharmaceuticals. SUMMARY

[0005] The present application provides a first-principle-based radiopharmaceutical molecular design method, which improves the balance of drug targeting, stability, and efficacy and safety by constructing a "target-radionuclide-chelator-linker-ligand" collaborative design logic, optimizes alpha radionuclides specifically to reduce toxicity, and has wide scalability.

[0006] The application provides a first-principle-based radioactive targeting nuclide drug molecule design method, comprising: S1, screening a high-specificity target point meeting preset screening conditions based on preset requirements, and verifying potential of the high-specificity target point in combination with a ligand and radiation sensitivity through first-principle calculation; S2, screening a candidate nuclide according to a drug function and a ligand type corresponding to the high-specificity target point, verifying coordination stability of the nuclide with a chelating agent and matching of the ligand half-life through first-principle calculation; wherein the drug function includes a diagnostic function and a therapeutic function; S3, setting a bifunctional chelating agent adapted to the candidate nuclide, and optimizing a coordination configuration, a functional group and a labeling reaction condition thereof through first-principle calculation; S4, setting a ligand for the high-specificity target point, and optimizing binding free energy, water solubility and metabolic characteristics of the ligand with the high-specificity target point through first-principle calculation; S5, setting a linker connecting the bifunctional chelating agent and the ligand, and optimizing stability, albumin binding capacity and environmental responsiveness thereof through first-principle calculation; S6, assembling an initial molecular complex in the order of "nuclide-chelating agent-linker-ligand", and verifying overall stability, nuclide retention and drug metabolic characteristics of the initial molecular complex through first-principle calculation; S7, for an alpha nuclide in the initial molecular complex, optimizing anti-decay recoil ability, daughter nuclide fixation efficiency, evaluating radiation dose distribution to balance efficacy and toxicity, and obtaining a target molecular complex.

[0007] Further, the S1 specifically comprises: S101, setting preset screening conditions of a high-specificity target point, and obtaining a high-specificity target point meeting the preset screening conditions based on preset clinical requirements; wherein the preset screening conditions include: ① a ratio of expression amount of a diseased tissue to expression amount of a healthy tissue ≥ 10:1, and absolute expression amount of the target point in the diseased tissue ≥ 105 / cell; ② the target point participates in a tumor pathological biochemical process; ③ for a therapeutic target point, radiation sensitivity of a tumor cell corresponding to the target point meets: DNA double-strand break repair energy barrier ≥ 30 kcal / mol, and relative biological effectiveness of alpha / beta rays ≥ 2.0; S102, performing calculation on the high-specificity target point by using a density functional theory; specifically comprising: (1) obtaining electrostatic potential distribution of a protein active site of the high-specificity target point, hydrophobic region proportion and electron cloud density of key coordination atoms, determining a ligand binding site, and obtaining an electronic structure of the protein active site of the high-specificity target point; (2) Calculate the interaction energy ΔE between the core group of the candidate ligand and the active site of the highly specific target, satisfying ΔE≤-20kcal / mol, and the difference in interaction energy between the group and the highly expressed protein in healthy tissue ≥10kcal / mol; (3) The binding energy of the DNA base pairs of tumor cells was calculated by DFT and combined with the energy of the radionuclide radiation to verify the toxic response of the tumor to radiation corresponding to the high-specificity target.

[0008] Furthermore, in the preset screening condition ② of S101, the selected target is one or more of the following: prostate-specific membrane antigen PSMA, somatostatin receptor SSTR, fibroblast activation protein FAP, human epidermal growth factor receptor 2, and carbonic anhydrase IX.

[0009] Furthermore, S2 specifically includes: S201. Candidate nuclides are screened based on the diagnostic / therapeutic function and ligand type of the drug. The purity requirements for candidate nuclides are: long half-life impurity content ≤ 0.1%, specific activity ≥ 37 GBq / mg; specifically including: ① The diagnostic nuclides are selected from positron-emitting nuclides 18F, 68Ga, 89Zr or single-photon nuclides 99Tcᵐ, and the ratio of their physical half-life to the biological half-life of the target ligand is 0.5~2.0; ②The β⁻ radionuclide used in treatment is selected from 177Lu and 90Y, and the α radionuclide is selected from 225Ac, 223Ra, and 212Bi; S202. First-principles fit verification was performed using DFT and molecular dynamics combined calculations, including calculation of nuclide-chelating agent coordination stability, simulation of nuclide decay recoil effect, and matching of nuclide-ligand half-life.

[0010] Furthermore, S3 specifically includes: S301. A bifunctional chelating agent is set to meet the preset coordination function, linkage function, and labeling conditions; wherein, the coordination function is designed with a cavity structure based on the coordination number / ionic radius of the nuclide; the linkage function is set with functional groups that can couple with ligands, using amide bonds and ether bonds for linkage; the labeling conditions are set with a labeling reaction temperature ≤37℃, a reaction time ≤30min, and a labeling rate ≥95%; S302. Calculate and optimize the coordination configuration, functional groups, and labeling reaction conditions of the bifunctional chelating agent based on first-principles calculations; specifically: Coordination configuration optimization: The coordination bond length of the bifunctional chelator-nucleoside complex was calculated to ensure a deviation of ≤0.1Å, and the bond angle was calculated to ensure a deviation of ≤5°; For 212Bi, DOTAM was used to calculate its coordination stability with 212Bi.

[0011] Functional group modification: rigid groups are introduced into the bifunctional chelating agent backbone, and the frontier molecular orbital gap is calculated to satisfy the requirement of gap ≥ 5.0 eV; Labeling reaction energy barrier calculation: Calculate the energy barrier of the complexation reaction between the bifunctional chelator and the nuclide, ensuring that the energy barrier is ≤20kcal / mol to ensure that labeling is completed under mild conditions.

[0012] Furthermore, S4 specifically includes: S401. Design targeting ligands according to the type of the highly specific target, including small molecule ligands, peptide ligands, and antibody / nanocarrier ligands; wherein, the small molecule ligands contain target-specific binding groups, have a molecular weight ≤1000 Da, and a water solubility logP ≤0; the peptide ligands have 2-20 amino acid residues, and through non-natural amino acid substitution or cyclization modification, have an in vivo half-life ≥4 h; the antibody / nanocarrier ligands are nanobodies or antibody fragments, and the nanocarrier ligands contain active targeting groups; S402. Calculate and optimize the binding free energy, water solubility, and metabolic properties of the ligand with the highly specific target based on first-principles calculations; specifically: Binding free energy optimization: Calculate the binding free energy between the ligand and the target site, ensuring that the binding free energy is ≤-25kcal / mol; Water solubility and metabolic optimization: Calculate the hydrophobic parameter of the ligand and introduce hydroxyl and carboxyl groups to make the hydrophobic parameter of the ligand ≤0; calculate the binding energy of the ligand with CYP450 enzyme to meet the requirement of binding energy ≥-10kcal / mol; Nanocarrier ligand optimization: Calculate the binding energy between ligands on the nanocarrier surface and tumor cell receptors, simulate changes in the carrier's electronic structure under acidic conditions, and ensure that the nuclide release energy barrier meets the preset requirements.

[0013] Furthermore, S5 specifically includes: S501. A linker is provided to connect the bifunctional chelator and the ligand, satisfying a preset function; wherein, the preset function includes: using a PEG chain, amide bond, or thioether bond to ensure link stability; providing an albumin-binding group to prolong the blood half-life to ≥24h, or providing an environmentally responsive group to regulate pharmacokinetics; controlling the hydrophobic parameter of the water-soluble ligand of the linker degradation fragment to ≤-1.0 to achieve toxicity control; S502. Calculate and optimize the stability, albumin binding capacity, and environmental responsiveness of the ligand and the linker based on first-principles calculations; specifically: Stability calculation: Calculate the reaction energy barrier between the linker and GSH, satisfying the condition that the energy barrier is ≥30 kcal / mol; Albumin binding optimization: Calculate the binding energy of albumin-binding groups to the Sudlow I site of human serum albumin to meet the set requirements; Response optimization: The difference in protonation energy between pH 6.5 and pH 7.4 was calculated to be ≥8 kcal / mol to ensure tumor site-specific degradation.

[0014] Furthermore, S6 specifically includes: S601. An initial molecular complex satisfying preset synergistic conditions is obtained by assembling the components in the order of "nucleus-chelating agent-linker-ligand". The preset synergistic conditions include: a ratio of the physical half-life of the nucleus to the biological half-life of the chelating agent-ligand complex of 0.5–2.0; radiochemical purity ≥90% after incubation in serum at 37°C for 24 h; and binding specificity of the initial molecular complex to the target ≥90%. S602. Verify the overall stability, radionuclide retention, and drug metabolism characteristics of the initial molecular complex based on first-principles calculations; specifically: Overall stability: Simulating the physiological environment, the root mean square deviation (RMSD) of the initial molecular complex was calculated to stabilize the RMSD within 0.2~0.3 nm; Nuclide retention: Calculate the dissociation energy of the nuclide in the complex to meet the set requirements; Drug metabolism characteristics: The complex hydration energy was calculated to be ≤-500 kcal / mol, and the blood diffusion coefficient was ≥1.0×10-6 cm2 / s, to predict the blood clearance rate.

[0015] Furthermore, in S7, the evaluation of radiation dose includes calculating and optimizing the anti-decay recoil capability and daughter nuclide fixation efficiency through first-principles calculations, as well as: Anti-decay recoil capability: A recoil energy absorption structure is introduced between the chelator and ligand. The recoil energy absorption efficiency is simulated by MD, and the absorption efficiency is ≥30% and the nuclide dissociation rate is ≤12%. Daughter nuclide fixation efficiency: The binding energy between the daughter nuclide and the adsorption site is calculated by introducing the α-nuclide decay daughter nuclide into the initial complex.

[0016] Radiation dose assessment: Combine Monte Carlo simulation to calculate the energy deposition of alpha particles in tumor tissue.

[0017] The beneficial effects of this invention are as follows: This invention, driven by microscopic calculations at the atomic / electronic level and combined with domestically available target structure information, nuclide physical parameters, and reference values ​​of human physiological data, achieves precise optimization of the entire process from target screening to molecular complex assembly. By constructing a collaborative design logic of "target-nuclide-chelating agent-linker-ligand," it prioritizes domestically available nuclides, chelating agents, and ligand types, overcoming the limitations of single-element optimization and significantly improving the drug's targeting, stability, and the balance between efficacy and safety. Specific optimizations are made for the unique risks of alpha nuclides, such as decay recoil effect and daughter body diffusion, effectively reducing off-target toxicity and enhancing the feasibility of clinical application. This provides a systematic solution for the efficient and domestically developed research and development of radioactive targeted nuclide drugs. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the first-principles-based method for designing radioactive targeted nuclide drugs according to the present invention.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0021] This invention provides a first-principles-based method for designing radioactive targeted nuclide molecules. By constructing a synergistic design logic of "target-nucleus-chelating agent-linker-ligand", it improves the drug's targeting, stability, and the balance between efficacy and safety. Targeting the unique risks of alpha nuclides, it combines domestically feasible technical pathways for specific optimization to reduce toxicity and has broad scalability.

[0022] like Figure 1 As shown, this invention provides a first-principles-based method for designing radioactive targeted nuclide molecules, comprising: S1. Based on preset requirements, select highly specific targets that meet preset screening conditions, and verify the binding potential and radiosensitivity of the highly specific targets with ligands through first-principles calculations; specifically including the following steps: S101. Set preset screening criteria for high-specificity targets, and screen high-specificity targets that meet the following conditions based on preset clinical needs (such as common tumor types in China: prostate cancer, neuroendocrine tumors, liver cancer, etc.): ① The ratio of expression level in diseased tissue to expression level in healthy tissue is ≥10:1, and the absolute expression level of the target in diseased tissue is ≥10⁵ per cell; ② The target is involved in the pathochemical process of tumor (such as matrix remodeling and signaling pathway regulation). For example, the preferred targets include one or more of the following: prostate-specific membrane antigen (PSMA), somatostatin receptor (SSTR), fibroblast activating protein (FAP), human epidermal growth factor receptor 2 (HER2), and carbonic anhydrase IX (CAIX). ③ For therapeutic targets, the radiosensitivity of the corresponding tumor cells must meet the following requirements: DNA double-strand break repair barrier ≥30 kcal / mol, and relative biological effect (RBE) ≥2.0 against α / β rays.

[0023] S102, First-principles calculation verification Density functional theory (DFT, with B3LYP or PBE0 as the preferred functionals and LANL2DZ or def2-SVP as the preferred basis sets) was used to perform the following calculations for highly specific targets. The calculation process can refer to publicly available target protein structure data (such as those from the PDB database) and relevant structural information reported in domestic research, specifically including: (1) Calculate the electronic structure of the active site of the target protein: obtain the electrostatic potential distribution, the proportion of hydrophobic regions and the electron cloud density of key coordinating atoms (such as Zn²⁺ active center of PSMA) of the active site to determine the ligand binding site; (2) Predicting target-ligand binding specificity: Calculate the interaction energy (ΔE) between the core group of the candidate ligand (such as the glutamic acid-urea-lysine group of the PSMA ligand) and the active site of the target. ΔE is required to be ≤-20 kcal / mol, and the difference in interaction energy between the group and the protein highly expressed in healthy tissue (such as PSA) is ≥10 kcal / mol. (3) Assess the radiation sensitivity of the target: The binding energy of the DNA base pairs of tumor cells was calculated by DFT and combined with the radiation energy of the radionuclide (α-ray LET≥25keV / μm, β-ray LET≤1keV / μm) to verify the toxic response of the target tumor (such as domestic LNCaP prostate cancer cells and QGP-1 neuroendocrine tumor cells).

[0024] S2. Based on the drug function (diagnostic / therapeutic) and ligand type corresponding to the highly specific target, candidate nuclides that can be prepared or stably obtained domestically are screened. First-principles calculations are used to verify the coordination stability of the nuclide with the chelating agent and its matching with the ligand half-life; specifically including: S201. Screening candidate nuclides based on drug function (diagnosis / treatment) and ligand type: ① Diagnostic nuclides: selected from positron-emitting nuclide 18F (conventionally produced in domestic medical cyclotrons), 68Ga (supplied by commercial 68Ge / 68Ga generators), 89Zr (currently mainly for research collaboration in China), or single-photon nuclide 99Tcᵐ (half-life 6.00h), with the ratio of its physical half-life to the biological half-life of the target ligand being 0.5~2.0; ②Therapeutic radionuclides: a. β⁻ isotopes are selected from 177Lu (produced by irradiation in a domestic research reactor) and 90Y, and are suitable for tumors with a volume ≥5mm; b. The α-nuclides are selected from 225Ac (prepared by domestic proton accelerator and purified by extraction chromatography), 223Ra, and 212Bi (224Ra / 212Pb / 212Bi generator technology under development), which are suitable for small tumors, micrometastases, or β-ray-resistant tumors. ③ Purity requirements for target nuclides: long half-life impurity content ≤0.1% (e.g., 227Ac content ≤0.1% in 225Ac), specific activity ≥37GBq / mg (carrier-free nuclides are preferred).

[0025] S202. First-principles fit verification was performed using DFT + molecular dynamics (MD) joint calculations as follows: Nuclide-chelating agent coordination stability: Calculate the coordination bond energy between the nuclide and candidate chelating agents (such as DOTA, Macropa, Sar class); for α nuclides, Macropa chelating agents can be considered; Nuclide decay recoil effect simulation: For alpha nuclides, calculate the transport path of decay recoil energy in the "nuclide-chelating agent" complex, and evaluate the probability of coordinate bond breakage, requiring a breakage probability ≤15%; Nuclide-ligand half-life matching: The flexibility of ligand molecules is calculated by DFT (dahedral angle energy barrier ≤10kcal / mol is small molecule ligand, ≥20kcal / mol is antibody ligand), and combined with the physical half-life of the nuclide, a correlation model of "ligand flexibility-biological half-life-nucleus half-life" is established to ensure a matching degree of ≥80%.

[0026] S3. Set up a bifunctional chelating agent adapted to the candidate nuclide, and calculate and optimize its coordination configuration, functional groups and labeling reaction conditions using first-principles calculations. S301. Select bifunctional chelating agents that meet the following conditions to match candidate nuclides. Prioritize chelating agents such as DOTA and DOTAGA, which have mature synthesis experience in China. At the same time, new chelating agents such as Macropa, which have high potential for α nuclides, should also be included in the design consideration.

[0027] Coordination function: The cavity structure is designed based on the coordination number / ionic radius of the nuclide.

[0028] Linkage function: Contains functional groups that can couple with ligands (such as carboxyl, amino, isothiocyanate groups), preferably amide bond (-CONH-) or ether bond (-O-) linkage mode to avoid enzymatic degradation in vivo; Labeling conditions: Labeling reaction temperature ≤37℃ (to avoid destroying ligand activity), reaction time ≤30min, labeling rate ≥95%.

[0029] S302. Based on first-principles optimization, DFT calculations are used to optimize its coordination configuration, functional groups, and labeling reaction conditions (compatible with commonly used domestic radiolabeling equipment).

[0030] Coordination configuration optimization: Calculate the coordination bond length (deviation ≤ 0.1 Å) and bond angle (deviation ≤ 5°) of the bifunctional chelator-nucleoside complex to ensure a regular configuration; for 212Bi, use DOTAM (a DOTA derivative in which the carboxylic acid group is replaced with an amide group) to calculate its coordination stability with 212Bi.

[0031] Functional group modification: Introduce rigid groups (such as cyclohexyl) into the bifunctional chelating agent skeleton, calculate the frontier molecular orbital (HOMO-LUMO) band gap, and require a band gap ≥ 5.0 eV to improve radiation resistance stability; Labeling reaction energy barrier calculation: Calculate the energy barrier of the complexation reaction between the bifunctional chelator and the nuclide. The energy barrier should be ≤20 kcal / mol to ensure that labeling is completed under mild conditions (e.g., the reaction energy barrier between Sar-type chelators and 64Cu is ≤15 kcal / mol).

[0032] S4. Set up ligands targeting the highly specific target, and calculate and optimize their binding free energy, water solubility, and metabolic properties with the highly specific target using first-principles calculations; specifically including the following steps: S401. Design targeting ligands according to the type of the high-specificity target. These can be optimized based on previously reported high-affinity ligand structures (such as PSMA-617 and DOTATATE) or designed independently, meeting the following conditions: Small molecule ligands: containing target-specific binding groups (such as the glutamic acid-urea-lysine of PSMA ligand and the octreotide cyclic structure of SSTR ligand), with a molecular weight ≤1000 Da and water solubility logP≤0. Peptide ligands: 2-20 amino acid residues, stability is improved by non-natural amino acid replacement (such as D-amino acids) or cyclization modification, and the in vivo half-life is ≥4h; Antibody / nanocarrier ligand: The preferred antibody ligand is a nanobody (molecular weight 15kDa) or an antibody fragment (Fab fragment, molecular weight 50kDa). The nanocarrier ligand (such as pH-responsive liposomes) contains an active targeting group (such as transferrin, folic acid).

[0033] S402. First-principles optimization uses DFT calculations to optimize the binding free energy, water solubility, and metabolic properties of the target. The calculation process incorporates data on drug-metabolizing enzymes (such as the distribution of CYP450 subtypes) in the domestic population.

[0034] Optimization based on free energy (ΔG): Calculate the ΔG of the ligand and target, requiring ΔG ≤ -25 kcal / mol; for example, replacing the glutamate in the PSMA ligand with 3-N-oxalyl-L-2,3-diaminopropionic acid (ODAP) reduces ΔG from -25 kcal / mol to -23 kcal / mol, while simultaneously reducing bladder uptake by ≥30%; Water solubility and metabolic optimization: Calculate the hydrophobic parameter (logP) of the ligand and introduce hydroxyl (-OH) and carboxyl (-COOH) groups to make logP ≤ 0; calculate the binding energy of the ligand with the CYP450 enzyme, requiring a binding energy ≥ -10 kcal / mol to reduce the metabolic rate; Nanocarrier ligand optimization: Calculate the binding energy between ligands on the nanocarrier surface and tumor cell receptors (e.g., the binding energy between transferrin and transferrin receptor ≤ -18 kcal / mol), simulate the changes in the electronic structure of the carrier under acidic conditions, and ensure that the nuclide release energy barrier meets the preset requirements.

[0035] S5. Establish a linker connecting the bifunctional chelator and the ligand, and calculate and optimize its stability, albumin binding capacity, and environmental responsiveness using first-principles calculations; specifically including the following steps: S501. Design linkers that meet the following functions, using readily available linkers such as PEG chains and amide bonds, and introduce albumin-binding groups (such as 4-(p-iodophenyl)butyric acid) to regulate pharmacokinetics.

[0036] Linkage stability: PEG chains, amide bonds, or thioether bonds are used to avoid glutathione (GSH) or enzymatic degradation; Drug metabolism and pharmacokinetic regulation: Containing albumin-binding groups (such as 4-(p-iodophenyl)butyric acid, 4-(p-methoxyphenyl)butyric acid), prolonging the blood half-life to ≥24h; or containing environmentally responsive groups (such as pH-sensitive hydrazone bonds, enzyme-sensitive peptide bonds Gly-Phe-Leu-Gly), degrading at the tumor site; Toxicity control: The water-soluble linker degradation fragment has a logP ≤ -1.0, which accelerates renal clearance and reduces uptake by non-target organs.

[0037] S502. Based on first-principles optimization, the following optimizations are achieved through DFT calculations: Stability calculation: Calculate the reaction barrier between the linker and GSH, requiring a barrier ≥30 kcal / mol (if the PEG linker does not react, the reaction barrier of the maleimide-thiol linker is ≤20 kcal / mol, and the PEG linker is preferred). Albumin binding optimization: Calculate the binding energy of albumin-binding groups to the Sudlow I site of human serum albumin (HSA) to meet the set requirements; Response optimization: The difference in protonation energy between the calculated environmental response linker at pH 6.5 (tumor microenvironment) and pH 7.4 (normal tissue) is ≥8 kcal / mol, ensuring tumor-specific degradation.

[0038] S6. Assemble the initial molecular complex in the order of "nucleus-chelating agent-linker-ligand" and verify the overall stability, nucleus retention, and drug metabolism characteristics of the initial molecular complex through first-principles calculations; specifically including the following steps: S601. The initial molecular complex is assembled in the order of "nucleus-chelating agent-linker-ligand" and satisfies the following synergistic conditions: Nuclide-chelating agent-ligand half-life matching: The ratio of the physical half-life of the nuclide to the biological half-life of the chelating agent-ligand complex is 0.5~2.0; Overall stability: The complex showed a radiochemical purity of ≥90% after incubation in serum at 37°C for 24 hours. Targeting: The binding specificity of the complex to the target is ≥90% (non-target binding rate ≤10%).

[0039] S602. Based on first-principles calculations, the following collaborative verification was performed using DFT+MD joint calculations. The verification process incorporated domestically available physiological environment simulation parameters and referenced domestic radiopharmaceutical quality standards.

[0040] Overall conformational stability: Simulating physiological environment (37℃, pH 7.4), the root mean square deviation (RMSD) of the complex was calculated, and the RMSD was required to be stable within 0.2~0.3 nm; Nuclide retention: Calculate the dissociation energy of the nuclide in the complex to meet the set requirements; Drug metabolism and kinetic prediction: Calculate the complex hydration energy (≤-500kcal / mol) and blood diffusion coefficient (≥1.0×10-6cm2 / s) to predict the blood clearance rate.

[0041] S7. For the α nuclide in the initial molecular complex, calculate and optimize the anti-decay recoil capability and daughter nuclide fixation efficiency through first-principles calculations, evaluate the radiation dose distribution to balance the therapeutic effect and toxicity, and obtain the target molecular complex.

[0042] ① Anti-decay recoil capability: Considering the current research status of α nuclides, recoil energy absorption structures that can be synthesized domestically (such as aromatic rings and rigid cycloalkyl groups) are introduced.

[0043] A recoil energy absorption structure (such as an aromatic ring or a rigid cycloalkyl group) is introduced between the chelating agent and the ligand. The recoil energy absorption efficiency is simulated by MD, and the required absorption efficiency is ≥30% and the nuclide dissociation rate is ≤12%. ② Daughter nuclide fixation efficiency Introduce adsorption sites (such as crown ether groups) of α-nucleus decay daughters (such as 221Fr produced by the decay of 225Ac) into the complex, and calculate the binding energy between the daughter and the adsorption site.

[0044] ③ Radiation dose assessment: Radiation dose assessment can refer to the relevant guidelines of the International Commission on Radiological Protection (ICRP) and previous research data from domestic and foreign sources.

[0045] The energy deposition of alpha particles in tumor tissue was calculated using Monte Carlo simulation (MCNP).

[0046] S8, Experimental Verification S801. In vitro verification. Radionuclide labeling rate: determined by radiometric thin-layer chromatography (RTLC) or high-performance liquid chromatography (HPLC), requiring a labeling rate ≥95%; Binding affinity: determined by radioligand binding assay (RLBA), requiring IC50 ≤10 nM; Stability: after incubation in serum at 37℃ for 24 h, radiochemical purity ≥90%.

[0047] S802. In vivo validation. Pharmacokinetics: Assessed by small animal PET / CT or SPECT, requiring tumor uptake rate ≥5%ID / g (24h) and tumor-to-non-target ratio (e.g., tumor / kidney) ≥5; Efficacy: In tumor-bearing mouse models, tumor growth inhibition rate ≥80% and survival time extension ≥40%; Toxicity: Mouse body weight loss ≤10%, and normal blood routine and liver and kidney function indicators.

[0048] S803 compares the results of first-principles calculations with experimental data and adjusts the parameters of the calculation model accordingly to continuously improve the accuracy of calculation predictions.

[0049] This invention, driven by microscopic calculations at the atomic / electronic level and combined with domestically available target structure information, nuclide physical parameters, and reference values ​​of human physiological data, achieves precise optimization of the entire process from target screening to molecular complex assembly. By constructing a collaborative design logic of "target-nucleus-chelating agent-linker-ligand," it prioritizes domestically available nuclides, chelating agents, and ligand types, overcoming the limitations of single-element optimization and significantly improving the drug's targeting, stability, and the balance between efficacy and safety. Specific optimizations address the unique risks of alpha nuclides, such as decay recoil effect and daughter body diffusion, effectively reducing off-target toxicity and enhancing the feasibility of clinical application. This provides a systematic solution for the efficient and domestically developed research and development of radioactive targeted nuclide drugs. It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, apparatus, article, or method. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, apparatus, article, or method that includes that element.

[0050] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A first-principles based radiotherapeutic targeting nuclide pharmaceutical molecule design method, characterized by, The application relates to a method for designing a high-specificity target point-based molecular complex, comprising the following steps: S1, screening a high-specificity target point meeting preset screening conditions based on preset requirements, and verifying the potential of the high-specificity target point in combination with a ligand and the radiosensitivity by first-principle calculation; S2, screening a candidate nuclide according to the drug function and the ligand type corresponding to the high-specificity target point, verifying the coordination stability of the nuclide and a chelating agent and the matching of the half-life of the ligand by first-principle calculation; wherein the drug function comprises a diagnosis function and a treatment function; S3, setting a bifunctional chelating agent adapted to the candidate nuclide, and optimizing the coordination configuration, the functional group and the labeling reaction condition of the bifunctional chelating agent by first-principle calculation; S4, setting a ligand for the high-specificity target point, and optimizing the binding free energy, the water solubility and the metabolic characteristics of the ligand with the high-specificity target point by first-principle calculation; S5, setting a linker connecting the bifunctional chelating agent and the ligand, and optimizing the stability, the albumin binding capacity and the environmental responsiveness of the linker by first-principle calculation; S6, assembling an initial molecular complex in the order of "nuclide-chelating agent-linker-ligand", and verifying the overall stability, the nuclide retention and the drug metabolic characteristics of the initial molecular complex by first-principle calculation; S7, for the alpha nuclide in the initial molecular complex, optimizing the anti-decay recoil ability and the daughter nuclide fixation efficiency by first-principle calculation, and evaluating the radiation dose distribution to balance the curative effect and the toxicity, so as to obtain a target molecular complex.

2. The first-principles based radiotargeted nuclide pharmaceutical molecule design method of claim 1, wherein, The S1 specifically comprises: S101, setting preset screening conditions of a high-specificity target point, and obtaining a high-specificity target point meeting the preset screening conditions based on preset clinical requirements; wherein the preset screening conditions comprise: ① the ratio of the expression amount of a lesion tissue to the expression amount of a healthy tissue is greater than or equal to 10:1, and the absolute expression amount of the target point in the lesion tissue is greater than or equal to 105 / cell; ② the target point participates in the pathological biochemical process of a tumor; ③ for a treatment target point, the radiosensitivity of the corresponding tumor cell satisfies: the DNA double-strand break repair energy barrier is greater than or equal to 30 kcal / mol, and the relative biological effect of alpha / beta rays is greater than or equal to 2.0; S102, performing calculation on the high-specificity target point by using a density functional theory; specifically comprising: (1) obtaining the protein active site electrostatic potential distribution, the hydrophobic region proportion and the electron cloud density of key coordination atoms of the high-specificity target point, determining a ligand binding site, and obtaining the electronic structure of the high-specificity target point protein active site; (2) calculating the interaction energy ΔE of a candidate ligand core group and the active site of the high-specificity target point, and satisfying ΔE≤-20 kcal / mol, and the interaction energy difference of the group and the highly expressed protein of a healthy tissue is greater than or equal to 10 kcal / mol; (3) verifying the killing response of the high-specificity target point to radiation of a tumor by combining the DNA base pair binding energy of a tumor cell with the nuclide ray energy through DFT calculation.

3. The first-principles based radiotargeted nuclide pharmaceutical molecule design method of claim 2, wherein, In the preset screening condition ② of the S101, the selected target point is one or more of a prostate-specific membrane antigen PSMA, a somatostatin receptor SSTR, a fibroblast activation protein FAP, a human epidermal growth factor receptor 2 and carbonic anhydrase IX.

4. The first-principles based radiotargeted nuclide pharmaceutical molecule design method of claim 1, wherein, The S2 specifically comprises: S201, screening candidate nuclides according to the diagnostic function / therapeutic function of the drug and the type of ligand, the purity requirement of the candidate nuclides being that the content of long half-life impurities is ≤0.1%, and the specific activity is ≥37 GBq / mg; specifically comprising: ① the diagnostic nuclide is selected from the positive electron nuclide 18F, 68Ga, 89Zr or the single photon nuclide 99Tcᵐ, and the ratio of the physical half-life to the biological half-life of the targeting ligand is 0.5-2.0; ② the β⁻ nuclide in the therapeutic nuclide is selected from 177Lu, 90Y, and the α nuclide is selected from 225Ac, 223Ra and 212Bi; S202, first-principle adaptability verification is performed through DFT+molecular dynamics joint calculation, including nuclide-chelating agent coordination stability calculation, nuclide decay recoil effect simulation, and nuclide-ligand half-life matching.

5. The first-principles based radiotargeted nuclide pharmaceutical molecule design method of claim 1, wherein, The S3 specifically comprises: S301, setting a bifunctional chelating agent meeting preset coordination function, connection function and labeling conditions; wherein, in the coordination function, a cavity structure is designed for the coordination number / ion radius of the nuclide; in the connection function, a functional group capable of coupling with the ligand is arranged, and an amide bond, an ether bond connection mode is adopted; in the labeling condition, the labeling reaction temperature is ≤37℃, the reaction time is ≤30 min, and the labeling rate is ≥95%; S302, the coordination configuration, functional group and labeling reaction condition of the bifunctional chelating agent are calculated and optimized based on the first principle; specifically: Coordination configuration optimization: the coordination bond length of the bifunctional chelating agent-nuclide complex is calculated so that the deviation is ≤0.1Å, and the bond angle is calculated so that the deviation is ≤5°; for 212Bi, DOTAM is used, and the coordination stability of 212Bi is calculated; Functional group modification: a rigid group is introduced into the bifunctional chelating agent skeleton, and the front molecular orbital energy gap is calculated to meet the energy gap ≥5.0eV; Labeling reaction energy barrier calculation: the complexing reaction energy barrier of the bifunctional chelating agent and the nuclide is calculated to meet the energy barrier ≤20 kcal / mol, so as to ensure that the labeling is completed under mild conditions.

6. The first-principles based radiotargeted nuclide pharmaceutical molecule design method of claim 1, wherein, The S4 specifically comprises: S401, designing a targeting ligand according to the type of the high-specificity target point, including a small molecule ligand, a polypeptide ligand, an antibody / nano-carrier ligand; wherein, the small molecule ligand contains a target point specific binding group, the molecular weight is ≤1000 Da, and the water solubility logP is ≤0; the number of amino acid residues in the polypeptide ligand is 2-20, which is replaced by a non-natural amino acid or modified by cyclization, and the in-vivo half-life is ≥4 h; the antibody ligand in the antibody / nano-carrier ligand is a nanobody or an antibody fragment, and the nano-carrier ligand contains an active targeting group; S402, the binding free energy, water solubility and metabolic characteristics of the ligand and the high-specificity target point are calculated and optimized based on the first principle; specifically: Binding free energy optimization: the binding free energy of the ligand and the target point is calculated to meet the binding free energy ≤-25 kcal / mol; Water solubility and metabolism optimization: the hydrophobic parameter of the ligand is calculated, the hydrophobic parameter of the ligand is ≤0 by introducing a hydroxyl group and a carboxyl group, the binding energy of the ligand and CYP450 enzyme is calculated to meet the binding energy ≥-10 kcal / mol; Nanocarrier ligand optimization: calculate the binding energy of nanocarrier surface ligand and tumor cell receptor, simulate the change of carrier electronic structure in acidic environment, and ensure that the energy barrier of radionuclide release meets the preset requirements.

7. The first-principles based radiotargeted nuclide pharmaceutical molecule design method of claim 1, wherein, The S5 specifically includes: S501, setting a linker for connecting the bifunctional chelator and the ligand to meet the preset function; wherein the preset function includes: using PEG chain, amide bond or sulfide bond to ensure the stability of the connection; setting an albumin binding group to extend the blood half-life to ≥24h, or setting an environment responsive group for pharmacokinetic regulation; controlling the water solubility of the ligand degradation fragment of the linker to be ≤-1.0 to achieve toxicity control; S502, based on first-principle calculation and optimization of the stability, albumin binding ability and environmental responsiveness of the ligand and the linker; specifically: Stability calculation: calculate the reaction energy barrier of the linker and GSH, and meet the energy barrier ≥30kcal / mol; Albumin binding optimization: calculate the binding energy of the albumin binding group and human serum albumin Sudlow I site to meet the set requirements; Responsiveness optimization: calculate the difference in protonation energy of the environmental response linker at pH 6.5 and pH 7.4 ≥8kcal / mol, to ensure tumor site-specific degradation.

8. The first-principles based radiotargeted nuclide pharmaceutical molecule design method of claim 1, wherein, The S6 specifically includes: S601, according to the order of "radionuclide-chelator-linker-ligand", assemble to obtain an initial molecular complex that meets the preset synergistic conditions; wherein the preset synergistic conditions include: the ratio of radionuclide physical half-life to chelator-ligand complex biological half-life is 0.5~2.0; the initial molecular complex is incubated in serum at 37℃ for 24h, and the radiochemical purity is ≥90%; the binding specificity of the initial molecular complex to the target is ≥90%; S602, based on first-principle calculation, verify the overall stability, radionuclide retention and drug metabolism characteristics of the initial molecular complex; specifically: Overall stability: simulate the physiological environment, calculate the root mean square deviation (RMSD) of the initial molecular complex, so that the RMSD is stable at 0.2~0.3nm; Radionuclide retention: calculate the dissociation energy of radionuclide in the complex to meet the set requirements; Drug metabolism characteristics: calculate the hydration energy of the complex ≤-500kcal / mol, and the blood diffusion coefficient ≥1.0×10-6cm2 / s, and predict the blood clearance rate.

9. The first-principles based radiotargeted nuclide pharmaceutical molecule design method of claim 1, wherein, In S7, the anti-decay recoil ability, daughter radionuclide fixation efficiency are calculated and optimized by first-principle calculation, and the radiation dose is evaluated, including: Anti-decay recoil ability: introduce recoil energy absorption structure between chelator-ligand, simulate the recoil energy absorption efficiency by MD, meet the absorption efficiency ≥30%, and the radionuclide dissociation rate ≤12%; Daughter radionuclide fixation efficiency: introduce adsorption sites of alpha radionuclide daughter in the initial complex, calculate the binding energy of the daughter and the adsorption site; Radiation dose evaluation: combine Monte Carlo simulation to calculate the energy deposition of alpha particles in tumor tissue.

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