Dimer-labeled precursor targeting CXCR4 receptor and radioactive tracer derived therefrom

Abstract

The present invention relates to the technical field of molecular imaging probes, and in particular to a dimer-labeled precursor targeting CXCR4 receptor and a radioactive tracer derived therefrom. 68 Ga]Ga-SDNUM01, a radioactive tracer derived from a precursor labeled for targeting CXCR4 receptor dimer provided by the present invention [ 68 Ga]Ga‑SDNUM04 remained in the tumor for a longer time and showed excellent imaging effect even at 45 minutes.

Description

Technical Field

[0001] The present invention relates to the technical field of molecular imaging probes, and in particular to a dimer-labeled precursor targeting a CXCR4 receptor and a radioactive tracer derived therefrom. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] CXC family chemokine receptor 4 (CXCR4) is one of the hot targets for global drug development. The CXCR4 receptor belongs to the G protein-coupled receptor (GPCR) family and is a specific receptor for the chemokine stromal cell-derived factor-1 (CXCL12). Studies have shown that the CXCR4 receptor is overexpressed in more than 70% of human cancers and plays an important role in tumor growth, invasion, angiogenesis, metastasis and resistance to therapeutic drugs. Its expression is often associated with the severity of the disease. Currently, many CXCR4 receptor antagonists, including small molecules, peptides and monoclonal antibodies, have been developed as carriers to deliver radionuclides to CXCR4 receptor-positive tumors for PET imaging.

[0004] Although a variety of radiotracers targeting CXCR4 receptors have been developed, most of them exist in monomeric form, and research on dimeric tracers is relatively scarce. Dimeric radiotracers have attracted much attention due to their unique advantages. Dimerization can not only prolong their retention time in tumors, but also enhance tumor uptake of radiotracers. Based on this, the development of dimeric radiotracers targeting CXCR4 receptors shows broad application prospects. Summary of the invention

[0005] In order to overcome the above problems, the present invention provides a dimer-labeled precursor targeting CXCR4 receptor and a radioactive tracer derived therefrom.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] The first aspect of the present invention provides a dimer-labeled precursor targeting CXCR4 receptor, the structural formula of which is shown in formula (I):

[0008]

[0009] Formula (I).

[0010] The second aspect of the present invention provides a method for preparing a dimer-labeled precursor targeting the CXCR4 receptor, comprising:

[0011] Compound 1 was deprotected by Boc using trifluoroacetic acid, and then 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU), Boc-L-glutamic acid-1-tert-butyl ester and N,N-diisopropylethylamine (DIPEA) were added for condensation reaction to obtain compound 2;

[0012] Compound 2 is de-Boc-protected by using trifluoroacetic acid, and then a chelating agent tetraazacyclododecane tetraacetic acid-succinimidyl ester (DOTA-NHS) and N,N-diisopropylethylamine (DIPEA) are added for condensation reaction to obtain the dimer-labeled precursor targeting the CXCR4 receptor;

[0013] The structural formula of compound 1 is shown below:

[0014]

[0015] The structural formula of compound 2 is shown below:

[0016] .

[0017] The third aspect of the present invention provides a radioactive tracer, comprising the dimer-labeled precursor targeting CXCR4 receptor described in the first aspect and / or the dimer-labeled precursor targeting CXCR4 receptor prepared by the preparation method described in the second aspect and a radioactive nuclide.

[0018] The fourth aspect of the present invention provides a method for preparing the radioactive tracer according to the third aspect, comprising:

[0019] The radioactive tracer is obtained by mixing and reacting the radioactive nuclide with the dimer labeling precursor targeting the CXCR4 receptor.

[0020] The fifth aspect of the present invention provides the use of the radioactive tracer described in the third aspect and / or the radioactive tracer prepared by the preparation method described in the fourth aspect in preparing a preparation for detecting the expression level of CXCR4 receptor in tumors.

[0021] The sixth aspect of the present invention provides the use of the radioactive tracer described in the third aspect and / or the radioactive tracer prepared by the preparation method described in the fourth aspect in the preparation of a preparation for diagnosing and / or treating CXCR4-overexpressing tumors.

[0022] The beneficial effects of the present invention are:

[0023] (1) After the dimer-labeled precursor targeting the CXCR4 receptor provided by the present invention is combined with a radionuclide, the CXCR4 receptor can be accurately located in vivo, and the in vivo targeting performance is excellent, and the purpose of tumor molecular imaging can be achieved through nuclear medicine imaging.

[0024] (2) The present invention realizes non-invasive visualization of CXCR4 molecular expression, examines the tumor imaging effect of radioactive tracers through small animal PET / CT, and realizes non-invasive diagnosis of tumors, so it has good clinical application prospects.

[0025] (3) Compared with [ 68 Ga]Ga-SDNUM01, a radioactive tracer derived from a precursor labeled for targeting CXCR4 receptor dimer provided by the present invention [ 68 Ga]Ga-SDNUM04 remained in the tumor longer and showed excellent imaging effect even at 45 minutes. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0027] Figure 1 A synthetic route for the dimer-tagged precursor SDNUM04 targeting the CXCR4 receptor;

[0028] Figure 2 is the high-resolution mass spectrum of compound 1;

[0029] Figure 3 is the H NMR spectrum of compound 1;

[0030] Figure 4 is the high-resolution mass spectrum of compound 2;

[0031] Figure 5 is the H NMR spectrum of compound 2;

[0032] Figure 6 High-resolution mass spectrometry of the dimer-labeled precursor SDNUM04 targeting the CXCR4 receptor;

[0033] Figure 7 For radioactive tracers 68 Ga]Ga-SDNUM04 radiochemical purity test chart;

[0034] Figure 8 For radioactive tracers 68 Results of the cellular uptake experiment of Ga]Ga-SDNUM04;

[0035] Fig. 9 For radioactive tracers68 Ga]Ga-SDNUM04 cell saturation experimental results;

[0036] Fig.10 For radioactive tracers 68 Blood clearance curve of Ga]Ga-SDNUM04;

[0037] Fig.11 for[ 68 Ga]Ga-SDNUM01 and [ 68 PET / CT imaging of Ga]Ga-SDNUM04 in tumor-bearing mice;

[0038] Fig.12 Immunohistochemical staining of HT-29 cell tumor sections;

[0039] Fig.13 Immunohistochemical staining of U87MG cell tumor sections;

[0040] Fig.14 for[ 68 Ga]Ga-SDNUM01 and [ 68 Ga]Ga-SDNUM04 biodistribution in vivo;

[0041] Fig.15 for[ 68 Ga]Ga-SDNUM01 and [ 68 Ga]Ga-SDNUM04 autoradiography. DETAILED DESCRIPTION

[0042] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0043] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0044] The first typical embodiment of the present invention provides a dimer labeled precursor targeting CXCR4 receptor, the structural formula of which is shown in formula (I):

[0045]

[0046] Formula (I).

[0047] The compound represented by formula (I), in addition to the small molecule entity having the above structure, the stereoisomers and physiologically acceptable salts of the compound also belong to the technical solution under the same concept as the first aspect of the present invention, and belong to the technical content of the present invention.

[0048] Among them, physiologically acceptable salts refer to organic salts and inorganic salts of the compounds of the present invention. Physiologically acceptable salts are well known to those skilled in the art. Physiologically acceptable salts include, but are not limited to, inorganic acid salts such as hydrochlorides, hydrobromides, phosphates, sulfates, perchlorates, etc., and organic acid salts such as acetates, oxalates, maleates, tartrates, citrates, succinates, malonates, etc., or salts obtained by other methods described in the literature such as ion exchange methods.

[0049] A second typical embodiment of the present invention provides a method for preparing a dimer labeled precursor targeting the CXCR4 receptor, comprising:

[0050] Compound 1 was deprotected by Boc using trifluoroacetic acid, and then 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU), Boc-L-glutamic acid-1-tert-butyl ester and N,N-diisopropylethylamine (DIPEA) were added for condensation reaction to obtain compound 2;

[0051] Compound 2 is de-Boc-protected by using trifluoroacetic acid, and then a chelating agent tetraazacyclododecane tetraacetic acid-succinimidyl ester (DOTA-NHS) and N,N-diisopropylethylamine (DIPEA) are added for condensation reaction to obtain the dimer-labeled precursor targeting the CXCR4 receptor;

[0052] The structural formula of compound 1 is shown below:

[0053]

[0054] The structural formula of compound 2 is shown below:

[0055] .

[0056] In one or more embodiments, the method of removing Boc protection from compound 1 using trifluoroacetic acid comprises:

[0057] Compound 1 was dissolved in a mixed solution of trifluoroacetic acid and dichloromethane, and after the reaction, the solution was concentrated to remove the trifluoroacetic acid.

[0058] Preferably, in the mixed solution of trifluoroacetic acid and dichloromethane, the volume ratio of trifluoroacetic acid to dichloromethane is 1:(3-5), preferably 1:4.

[0059] In one or more embodiments, the method of adding 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU), Boc-L-glutamic acid-1-tert-butyl ester and N,N-diisopropylethylamine (DIPEA) to carry out a condensation reaction includes:

[0060] The de-Boc protected mixture, 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU), Boc-L-glutamic acid-1-tert-butyl ester and N,N-diisopropylethylamine (DIPEA) were added to an organic solvent and stirred for reaction to obtain compound 2.

[0061] Preferably, the organic solvent is N,N-dimethylformamide (DMF).

[0062] In one or more embodiments, the molar ratio of compound 1, 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU), Boc-L-glutamic acid-1-tert-butyl ester and N,N-diisopropylethylamine is (60-65):(82-84):(26-30):(160-170), preferably 63.6:83:27.9:166.3.

[0063] In one or more embodiments, the method of removing Boc protection from compound 2 using trifluoroacetic acid comprises:

[0064] Compound 2 was dissolved in a mixed solution of trifluoroacetic acid and dichloromethane, and after the reaction, the solution was concentrated to remove the trifluoroacetic acid.

[0065] Preferably, in the mixed solution of trifluoroacetic acid and dichloromethane, the volume ratio of trifluoroacetic acid to dichloromethane is 1:(3-5), preferably 1:4.

[0066] In one or more embodiments, the method of adding a chelating agent tetraazacyclododecane tetraacetic acid-succinimide ester (DOTA-NHS) and N,N-diisopropylethylamine (DIPEA) to carry out a condensation reaction comprises:

[0067] The de-Boc protected mixture and the chelating agent tetraazacyclododecane tetraacetic acid-succinimide ester are added to an organic solvent, and N,N-diisopropylethylamine is added to react to obtain the dimer labeled precursor targeting the CXCR4 receptor.

[0068] Preferably, the organic solvent is N,N-dimethylformamide (DMF).

[0069] In one or more embodiments, the molar ratio of the compound 2 to the chelating agent tetraazacyclododecane tetraacetic acid-succinimide ester is 1:(0.9-1.2), preferably 1:1.

[0070] In one or more embodiments, the molar ratio of the compound 2 to N,N-diisopropylethylamine is 1:(9-10), preferably 1:9.5.

[0071] A third typical embodiment of the present invention provides a radioactive tracer, comprising the dimer-labeled precursor targeting CXCR4 receptor described in the first aspect and / or the dimer-labeled precursor targeting CXCR4 receptor prepared by the preparation method described in the second aspect and a radioactive nuclide.

[0072] In one or more embodiments, the radionuclide comprises 18 F. 94 Tc, 99m Tc, 90 In, 111 In, 67 Ga, 68 Ga, 86 Y. 90 Y. 177 Lu, 151 Tb, 186 Re, 188 Re, 64 Cu, 67 Cu, 55 Co. 57 Co. 43 Sc, 44 Sc, 47 Sc, 225 Ac, 213 Bi, 212 Bi, 212 Pb, 227 Th, 153 Sm, 166 Ho, 152 Gd, 153 Gd, 157 Gd or 166 One of Dy; preferably 68 Ga.

[0073] More preferably, the structural formula of the radioactive tracer is as shown in formula (II),

[0074]

[0075] Formula (II).

[0076] A fourth typical embodiment of the present invention provides a method for preparing the radioactive tracer according to the third aspect, comprising:

[0077] The radioactive tracer is obtained by mixing and reacting the radioactive nuclide with the dimer labeling precursor targeting the CXCR4 receptor.

[0078] A fifth typical embodiment of the present invention provides use of the radioactive tracer described in the third aspect and / or the radioactive tracer prepared by the preparation method described in the fourth aspect in preparing a preparation for detecting the expression level of CXCR4 receptor in tumors.

[0079] A sixth typical embodiment of the present invention provides use of the radioactive tracer described in the third aspect and / or the radioactive tracer prepared by the preparation method described in the fourth aspect in preparing a preparation for diagnosing and / or treating CXCR4-highly expressing tumors.

[0080] The above tumors include any one of lymphoma, multiple myeloma and solid tumors, such as lung cancer, liver cancer, pancreatic cancer, stomach cancer, colon cancer, thyroid cancer and head and neck tumors, but are not limited thereto.

[0081] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0082] Figure 1 The synthetic route of the dimer labeled precursor SDNUM04 targeting CXCR4 receptor in the present invention is as follows: Figure 1 , synthesized the dimer-tagged precursor SDNUM04 targeting the CXCR4 receptor.

[0083] Example 1

[0084] 2-Aminopyrimidine (905 mg, 9.5 mmol), tert-butyl 4-bromomethylbenzylcarbamate (1200 mg, 4 mmol) and potassium carbonate (1100 mg, 7.97 mmol) were dissolved in methanol (5 mL), reacted at 65 °C for 2 hours, filtered, concentrated and purified by column chromatography (SiO2) to obtain compound 1 (808 mg, yield 64%).

[0085] The high-resolution mass spectrum of compound 1 is shown in Figure 2 As shown, the H NMR spectrum of compound 1 is as follows Figure 3 shown.

[0086] Compound 1 (200 mg, 0.636 mmol) was dissolved in 2 mL of trifluoroacetic acid (TFA) and dichloromethane (DCM) (volume ratio 1:4), reacted at room temperature for 30 min, and concentrated to remove TFA. The mixture (119 mg), 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU) (317 mg, 0.83 mmol), Boc-L-glutamic acid-1-tert-butyl ester (69 mg, 0.279 mmol), and DIPEA (215 mg, 1.663 mmol) were dissolved in 5 mL of DMF and stirred overnight at room temperature. The reaction system was extracted five times with 100 mL of ethyl acetate and 100 mL of saturated brine, DMF was removed, the organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated. Detected by TLC, separated and purified by silica gel column, and concentrated to obtain compound 2 (101 mg, yield 50%).

[0087] The high-resolution mass spectrum of compound 2 is shown in Figure 4 As shown, the H NMR spectrum of compound 2 is as follows Figure 5 shown.

[0088] Compound 2 (40 mg, 0.06 mmol) was dissolved in 2 mL of trifluoroacetic acid (TFA) and dichloromethane (DCM) (volume ratio of 1:4), reacted at room temperature for 30 min, concentrated to remove TFA, and the mixture was dissolved in 1 mL of DMF with DOTA-NHS (30 mg, 0.06 mmol). DIPEA (74.2 mg, 0.57 mmol) was added and reacted at room temperature for 8 h. The mixture was purified by HPLC (reverse phase column, 5% acetonitrile containing 0.1% TFA-95% acetonitrile containing 0.1% TFA, flow rate 3 mL / min) and lyophilized to obtain the dimer-labeled precursor SDNUM04 targeting the CXCR4 receptor (7.7 mg, yield 56%).

[0089] The high-resolution mass spectrometry results of the dimer-labeled precursor SDNUM04 targeting the CXCR4 receptor are shown in Figure 6.

[0090] Example 2

[0091] The dimer-labeled precursor SDNUM04 (4 nmol) targeting the CXCR4 receptor was dissolved in 100 μL of NaOAc buffer (concentration: 0.1 M, pH 4.6), and then 400 μL of 68 GaCl3 solution (2 mCi) was reacted at 95 °C for 20 min to obtain the radioactive tracer [ 68 Ga]Ga-SDNUM04.

[0092] The radioactive tracer prepared in this example [68 The radiochemical purity of Ga]Ga-SDNUM04 was tested by analytical HPLC with a radioactivity detector. The HPLC results are shown in Figure 7 As shown, from Figure 7 As can be seen in the figure, the radiotracer [ 68 The radiochemical purity of Ga]Ga-SDNUM04 is greater than 95%.

[0093] Among them, the HPLC mobile phase (A = 0.1% TFA / water, B = 0.1% TFA / acetonitrile), Zorbax 5 μ C18 100 Å (250 × 4.6 mm, 5 μm), and the HPLC elution conditions are shown in Table 1.

[0094] Table 1 HPLC elution conditions

[0095]

[0096] Example 3

[0097] In vitro and in vivo stability studies:

[0098] For in vitro serum stability studies, 10 μL of radioactive tracer [ 68 Ga]Ga-SDNUM04 was added to 190 μL fetal bovine serum and incubated at 37 °C for 30 or 60 min. After incubation, the sample was added with anhydrous ethanol and centrifuged, filtered, and then tested for radiochemical purity.

[0099] For in vivo stability studies, healthy NSG female mice were used to evaluate the radiotracer [ 68 The metabolic stability of Ga]Ga-SDNUM04 in vivo. Each female mouse was injected with about 37 MBq of radioactive tracer [ 68 Ga]Ga-SDNUM04, 60 min after injection, blood, liver, and kidney samples were collected from three female mice, and radiochemical purity was tested after processing to observe the radiochemical purity in different samples.

[0100] The results of in vitro and in vivo stability studies are shown in Table 2.

[0101] Table 2 In vivo and in vitro stability

[0102]

[0103] From Table 2, we can see that 68 Ga]Ga-SDNUM04 has good stability in vivo and in vitro and can be used for subsequent experimental research.

[0104] Example 4

[0105] Hydrophilicity and lipophilicity determination:

[0106] 10 μL radiotracer [ 68 Ga]Ga-SDNUM04 was diluted to 500 μL with HEPES buffer at pH = 7.4, and then 500 μL of n-octanol was added and shaken vigorously. 100 μL of liquid was taken from each of the aqueous and organic phases to measure their radioactivity counts. The lipid-water partition coefficient was calculated using the formula [Log (radioactivity count of the organic phase / radioactivity count of the aqueous phase)], and the radioactive tracer [ 68 The log D of Ga]Ga-SDNUM04 is -2.89±0.03. The experimental results show that the radioactive tracer [ 68 Ga]Ga-SDNUM04 has high hydrophilicity.

[0107] Example 5

[0108] Cellular uptake and saturation experimental studies:

[0109] 5.1 Cell uptake experiment: For the cell uptake experiment, HT-29 cells were cultured at 3×10 5 Cells were seeded at a density of 100 μg / well in 24-well plates and incubated at 37 °C with a radioactive tracer [ 68 Ga]Ga-SDNUM04 (100 nM) was co-incubated for 15, 30, 60, and 120 min. To evaluate the specificity of uptake, a blocking experiment was performed using a 1000-fold molar concentration of the CXCR4-targeted inhibitor T140. After incubation, the cells were washed three times with PBS, lysed with 1 M NaOH solution, and the radioactivity of the cell suspension was quantified using a γ counter. The results are shown in Figure 8 As shown, from Figure 8 The radioactive tracer [ 68 The cellular uptake of Ga]Ga-SDNUM04 increased over time, compared with the radiotracer [ 68 Ga]Ga-SDNUM04 uptake was significantly reduced, indicating that the radiotracer [ 68 Ga]Ga-SDNUM04 binds specifically to the CXCR4 receptor.

[0110] 5.2 Cell saturation experiments: To evaluate the radiotracer 68 The binding affinity of Ga]Ga-SDNUM04 to CXCR4 receptor was determined using HT-29 cell line and the equilibrium dissociation constant (K d For cell saturation experiments, HT-29 cells were plated at 3 × 10 5 Cells were seeded at a density of 100 μg / well in 24-well plates and incubated with different concentrations of radiotracer [ 68The cells were incubated with 50 nM, 20 nM, 40 nM, 8 nM, 25 nM, 50 nM, and 100 nM of 50 μg / mL Ga]Ga-SDNUM04 (0.78125 nM, 1.5625 nM, 3.125 nM, 6.25 nM, 12.5 nM, 25 nM, 50 nM, and 100 nM) for 1 h. In parallel, nonspecific binding was assessed by co-incubating the cells with 1000-fold molar concentrations of the CXCR4-targeted inhibitor T140 over the same concentration range. After incubation, the radioactivity of the cell suspension was measured using a gamma counter, and the data were analyzed by nonlinear regression using GraphPadPrism 5.0 to determine K d The result is Fig. 9 As shown, from Fig. 9 As can be seen in the figure, the radiotracer [ 68 Ga]Ga-SDNUM04 has a high binding affinity to CXCR4 receptors, and the radiotracer [ 68 Ga]Ga-SDNUM04 K d The value was 32.21±0.71 nM. When incubated with T140 solution, the radioactive tracer [ 68 The binding of Ga]Ga-SDNUM04 to CXCR4 receptor was significantly blocked, indicating that its binding to CXCR4 is specific.

[0111] Example 6

[0112] Pharmacokinetic properties studies

[0113] Eight-week-old female BALB / c mice were injected with radiotracer via the tail vein. 68 Ga]Ga-SDNUM04 (0.2 mL, 7.4 MBq), and blood samples were collected from the tail vein at 1, 3, 5, 10, 15, 30, 45, 60, and 90 minutes after injection. The samples were weighed and their radioactivity was measured using a γ counter. The pharmacokinetic curves were characterized using DAS software. The results are shown in Fig.10 As shown. The drug concentration changes obtained by DAS software fitting reflect the summary of the distribution phase (α phase) and the elimination phase (β phase). The blood drug concentration in the distribution phase (α phase) drops rapidly after administration, which is the fast elimination phase. The drug concentration in the elimination phase (β phase) decreases proportionally according to the dynamic equilibrium law, which is the slow elimination phase. The radioactive tracer [ 68 The blood clearance curve of Ga]Ga-SDNUM04 conformed to the two-compartment model, with the distribution phase half-life (T1 / 2α) of 8.74±1.06 minutes and the elimination phase half-life (T1 / 2β) of 39.94±1.26 minutes, indicating a moderate blood metabolism time.

[0114] Example 7

[0115] Small Animal PET / CT Imaging:

[0116] Under anesthesia with 2% isoflurane in oxygen, a Mediso NanoScan μ-PET / CT scanner was used after injection of [ 68 Ga]Ga-SDNUM01 or [ 68 PET / CT imaging was performed 15 and 45 minutes after the injection of Ga]Ga-SDNUM04 (0.2 mL, 7.4 MBq). HT-29 tumor-bearing mice were randomly divided into an experimental group and a blocking group (n = 3). In the blocking group, mice were injected with [ 68 Ga]Ga-SDNUM01 or [ 68 Ga]Ga-SDNUM04 and T140 (20 mg / kg). In the negative control group, U87MG tumor-bearing mice with low CXCR4 expression were used for PET / CT imaging at the same time point. PET / CT images were reconstructed using Nucline NanoScan 3.00 software and subsequently analyzed using InterView FUSION 3.0 software. Fig.11 As shown, compared with the 15-minute imaging results, [ 68 Ga]Ga-SDNUM04 had excellent imaging quality at 45 minutes and a longer tumor retention time (SUV: 0.63±0.02). 68 The monomer form of Ga]Ga-SDNUM04[ 68 Ga]Ga-SDNUM01 also showed excellent imaging effect at 15 minutes (SUV: 0.86±0.03); however, due to its short tumor retention time, tumor uptake was significantly lower at 45 minutes (SUV: 0.31±0.01). In the blocking group and negative control group, tumor uptake was significantly reduced, suggesting that [ 68 Ga]Ga-SDNUM01, [ 68 Ga]Ga-SDNUM04 is highly specific for CXCR4 uptake.

[0117] in[ 68 The structural formula of Ga]Ga-SDNUM01 is shown below:

[0118] .

[0119] Example 8

[0120] HT29 cell and U87MG cell tumor-bearing mice were killed, their tumor tissues were isolated and tumor sections were prepared. The samples were fixed in 10% formalin, embedded in paraffin, cut into 5 μm thick sections and mounted on slides. The sections of the experimental group were incubated with rabbit anti-human CXCR4 antibody and then analyzed by immunohistochemical staining. The results are shown in the figure, where Fig.12 This is a HT-29 cell tumor section. Fig.13 This is a U87MG cell tumor section. The experimental results show that HT29 tumors are immunoreactive while U87MG is not.

[0121] Example 9

[0122] Biodistribution studies:

[0123] In the biodistribution study, HT-29 tumor-bearing mice were injected intravenously with 68 Ga]Ga-SDNUM01 or [ 68 Ga]Ga-SDNUM04 (0.1 mL, 3.7 MBq). Tumor-bearing mice were killed 15 minutes or 45 minutes after injection and tumors, blood, and a series of major tissues and organs (including heart, lung, liver, kidney, spleen, intestine, bone, and muscle) were collected. Each tissue and organ sample was weighed, and the radioactivity of each tissue and organ sample was measured using a γ counter. Fig.14 As shown, the biodistribution results are basically consistent with the PET imaging results. At 15 minutes, [ 68 Ga]Ga-SDNUM01 or [ 68 Ga]Ga-SDNUM04 showed high tumor uptake and good tumor-liver ratio. However, at 45 minutes, [ 68 Ga]Ga-SDNUM04 still has a high tumor uptake and tumor-liver ratio, while [ 68 The tumor uptake of Ga]Ga-SDNUM01 was significantly reduced. 68 Ga]Ga-SDNUM04 has an excellent tumor-to-muscle ratio, which is beneficial for its clinical tumor diagnosis.

[0124] Example 10

[0125] Autoradiography:

[0126] For autoradiography, tissue organs were placed on a phosphor screen and exposed for 10 min, and the screen was subsequently analyzed using a Cyclone Plus phosphorimaging system (Amersham TYPHOON, Cytiva, USA). Fig.15 Shown 68 Ga]Ga-SDNUM01 and [ 68 The results show that [ 68 Ga]Ga-SDNUM04 showed excellent tumor uptake and tumor-to-liver ratio at 45 min.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A dimer-labeled precursor targeting CXCR4 receptor, characterized in that: Its structural formula is shown in formula (I). Formula (I).

2. The method for preparing the dimer-labeled precursor targeting the CXCR4 receptor according to claim 1, comprising: Compound 1 was deprotected by Boc using trifluoroacetic acid, and then 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate, Boc-L-glutamic acid-1-tert-butyl ester and N,N-diisopropylethylamine were added for condensation reaction to obtain compound 2; Using trifluoroacetic acid to remove the Boc protection of compound 2, and then adding a chelating agent tetraazacyclododecane tetraacetic acid-succinimide ester and N,N-diisopropylethylamine to carry out a condensation reaction to obtain the dimer labeled precursor targeting the CXCR4 receptor; The structural formula of compound 1 is shown below: The structural formula of compound 2 is shown below: 。 3. The preparation method according to claim 2, characterized in that: The method of removing Boc protection from compound 1 using trifluoroacetic acid includes: Dissolve compound 1 in a mixed solution of trifluoroacetic acid and dichloromethane, and concentrate to remove trifluoroacetic acid after the reaction; The method of adding 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate, Boc-L-glutamic acid-1-tert-butyl ester and N,N-diisopropylethylamine to carry out condensation reaction comprises: The de-Boc protected mixture, 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate, Boc-L-glutamic acid-1-tert-butyl ester and N,N-diisopropylethylamine were added to an organic solvent and stirred to react to obtain compound 2.

4. The preparation method according to claim 2, characterized in that: The method of removing Boc protection from compound 2 using trifluoroacetic acid includes: Dissolve compound 2 in a mixed solution of trifluoroacetic acid and dichloromethane, and concentrate to remove trifluoroacetic acid after the reaction; The method of adding a chelating agent tetraazacyclododecane tetraacetic acid-succinimide ester and N,N-diisopropylethylamine to carry out a condensation reaction comprises: The de-Boc protected mixture and the chelating agent tetraazacyclododecane tetraacetic acid-succinimide ester are added to an organic solvent, and N,N-diisopropylethylamine is added to react to obtain the dimer labeled precursor targeting the CXCR4 receptor.

5. A radioactive tracer, characterized in that Composed of the dimer-labeled precursor targeting CXCR4 receptor according to claim 1 and / or the dimer-labeled precursor targeting CXCR4 receptor prepared by the preparation method according to any one of claims 2 to 4 and a radionuclide; The radionuclide is 111 In, 67 Ga, 68 Ga, 86 Y. 90 Y. 177 Lu, 64 Cu, 67 Cu, 55 Co. 57 Co. 43 Sc, 44 Sc, 47 Sc, 225 Ac, 213 Bi, 212 Bi, 212 Pb, 153 Sm, 166 Ho, 153 Gd or 157 One of Gd; The radioactive tracer is obtained by mixing and reacting the radioactive nuclide with the dimer labeling precursor targeting the CXCR4 receptor.

6. The radioactive tracer according to claim 5, characterized in that The structural formula of the radioactive tracer is shown in formula (II). Formula (II).

7. A method for preparing the radioactive tracer according to any one of claims 5 to 6, comprising: The radioactive tracer is obtained by mixing and reacting the radioactive nuclide with the dimer labeling precursor targeting the CXCR4 receptor.

8. Use of the radioactive tracer according to any one of claims 5 to 6 and / or the radioactive tracer prepared by the preparation method according to claim 7 in preparing a preparation for detecting the expression level of CXCR4 receptor in tumors.

9. Use of the radioactive tracer according to any one of claims 5 to 6 and / or the radioactive tracer prepared by the preparation method according to claim 7 in the preparation of a preparation for diagnosing tumors with high CXCR4 expression.

Images