A somatostatin type 2 receptor inhibitor, its radionuclide complex, preparation method and application

Abstract

The present invention discloses a somatostatin type 2 receptor inhibitor, its radionuclide complex, preparation method and application. The somatostatin type 2 receptor inhibitor has a structure shown in the following formula I: wherein, n is a natural number selected from 1 to 7. Based on the somatostatin type 2 receptor inhibitor, the complexes formed by labeling <supgt;99m< / supgt;Tc or <supgt;188< / supgt;Re can be respectively used for specific SPECT / CT imaging of somatostatin type 2 receptors or the treatment of neuroendocrine tumors. The complexes have the characteristics of high labeling rate, good stability and good tumor tissue targeting, providing a new idea for the integrated diagnosis and treatment of neuroendocrine tumors.

Description

Technical Field

[0001] The present invention belongs to the field of nuclear medicine, and relates to a somatostatin type 2 receptor inhibitor, a radionuclide complex thereof, a preparation method and an application. Specifically, it relates to a somatostatin type 2 receptor inhibitor and a radionuclide 188 Re or 99m a preparation method and an application of a Tc complex Background Art

[0002] Neuroendocrine tumors (NETs) refer to a type of tumor that originates from stem cells, has neuroendocrine markers, and can produce bioactive amines and / or polypeptide hormones. It can occur in tissues and organs throughout the body. Among them, gastrointestinal and pancreatic neuroendocrine tumors (GEP-NETs) are the most common, accounting for 55%-70% of all neuroendocrine tumors. GEP-NETs are a group of tumors that originate from the neuroectoderm and contain neuroendocrine granules, and can exist in different parts of the pancreas and gastrointestinal tract. The incidence of NETs in European and American countries is about 2.5-5 per 100,000 people, and the incidence has increased by 5 times in the past 30 years. Compared with other types of tumors, the incidence of NETs has increased significantly. The overall incidence of NETs in China is also on the rise. Although the incidence of NETs is very low, once diagnosed, it will pose a great threat to the life and health of patients. Data shows that once the tumor metastasizes, the 5-year survival rate of patients may be only 35%. For patients with advanced neuroendocrine tumors who progress during first-line somatostatin analogue treatment, the treatment options are limited, and there is an urgent need for an innovative therapy to meet the unmet medical needs in this field.

[0003] Somatostatin type II receptor (SSTR2) is a type of G protein-coupled receptor (GPCR), and its natural ligand is somatostatin (SST). SSTR2 is widely distributed in the body and is also highly expressed in a variety of neuroendocrine tumors. In vivo, SSTR2 is involved in the secretion regulation of multiple hormones, inhibits cell proliferation, and promotes cell apoptosis. It is an important target for the treatment of acromegaly and neuroendocrine tumors.

[0004] Peptide receptor radionuclide therapy (PRRT) is a new technology that uses radioactive drugs that specifically target peptide receptors to kill tumor cells. The radioactive drug carries a radionuclide that can emit β rays and is chelated with a somatostatin analogue to achieve a targeting effect on overexpressed somatostatin receptors. After the drug binds to the receptor, it enters the cell and releases radiation to damage the tumor cells. Therefore, PRRT will be a new treatment option for NETs patients.

[0005] In 2010, Advanced Accelerator Applications obtained the global exclusive license for the somatostatin analogue 177 Lu-oxodotrotide. In the United States and the European Union, Lutathera has been granted orphan drug status. In October 2017, the European Union approved it for the treatment of adult patients with unresectable or metastatic somatostatin receptor-positive gastroenteropancreatic neuroendocrine tumors. In early 2018, the FDA approved Lutathera for the treatment of adult patients with somatostatin receptor-positive gastroenteropancreatic neuroendocrine tumors. In the pivotal randomized phase 3 clinical study NETTER-1, 177 compared with double-dose long-acting octreotide, Lu-oxodotrotide can significantly reduce the risk of disease progression or death by 79%. Only 5% of the patients showed dose-adjusted toxicity, and the overall safety was good. In another trial of patients with GEP-NETs, 16% of the patients had partial tumor shrinkage.

[0006] However, radionuclides such as lutetium-177 can only be obtained from reactors or proton accelerators, with high production costs and poor clinical accessibility due to production limitations. Based on the clinical accessibility problems and synthetic process deficiencies of existing small molecule inhibitors of somatostatin receptor type 2 (SSTR2) labeled with radionuclides, the present invention provides a somatostatin receptor type 2 inhibitor, its radionuclide complex, preparation method and application.

[0007] In view of this, the present invention is specifically proposed. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a somatostatin receptor type 2 inhibitor, its radionuclide complex, preparation method and application. The somatostatin receptor type 2 inhibitor of the present invention can form a complex with a low-cost radionuclide. The complex has a high labeling rate, good stability, and better tumor tissue targeting, and can be used for SPECT / CT imaging of target tissues and tumor targeted therapy respectively, providing new ideas for the integration of diagnosis and treatment of neuroendocrine tumors.

[0009] To solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0010] The first object of the present invention is to provide a somatostatin receptor type 2 inhibitor having the structure shown in the following formula I:

[0011]

[0012] Wherein, n is a natural number selected from 1 to 7.

[0013] In a further embodiment, n is a natural number selected from 1 to 5; preferably, n = 2 or 3.

[0014] The somatostatin type 2 receptor inhibitor provided by the present invention as shown in the above structural formula can achieve the labeling of radionuclide 188 Re or 99m Tc. The labeling method is simple, convenient, fast, with a high labeling rate and low cost. In addition, S-Acetyl-MAG2-NH-(CH2)n-CO is introduced into the compound structure. For NH-(CH2)n-CO, when n is a natural number selected from 1 to 7, the lipophilicity of the whole compound can be moderately increased, and the spatial structure is appropriate, which can enhance the affinity with the somatostatin type 2 receptor, improve the targeting of the drug, and has good stability.

[0015] The second object of the present invention is to provide a preparation method of the somatostatin type 2 receptor inhibitor as described above, including:

[0016] Step (1): The solid-phase carrier resin is sequentially coupled with N-terminal and side-chain protected groups according to the amino acid sequence of β-Ala-D-Phe-(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH, and then S-Acetyl-MAG2 is coupled to obtain a linear resin peptide;

[0017] Step (2): Take the linear peptide resin obtained in step (1), add a cleavage solution to remove the protecting groups and cleave the resin to obtain a linear peptide;

[0018] Step (3): Oxidize the linear peptide with an oxidant to obtain a crude peptide.

[0019] In a further embodiment, using CTC resin as the starting material, Fmoc-Thr(tBu)-OH and Fmoc-Glu(OtBu)-OH are sequentially added, and amidation reactions and deprotection are carried out respectively;

[0020] Then Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-Trp-OH, Fmoc-Tyr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-D-Phe-OH, Fmoc-β-Ala-OH, Fmoc-Gly-OH and Fmoc-Gly-OH are sequentially added, and amidation reactions are carried out respectively;

[0021] Then 2-(acetythio)acetic acid is added for an amidation reaction, and then the remaining protecting groups and 2-CTC resin are removed;

[0022] Cyclization using I2 gives S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH.

[0023] In a further embodiment, when adding Fmoc-Thr(tBu)-OH, DIEA is used as the catalyst for the amidation reaction, and a 5% - 50% piperidine DMF solution is added to deprotect the group; preferably, based on the amount of 2-CTC resin used, the amount of Fmoc-Thr(tBu)-OH is 1 - 10 molar equivalents, and the amount of DIEA is 1 - 10 molar equivalents;

[0024] When adding Fmoc-Glu(OtBu)-OH, HBTU and DIEA are used as the catalysts for the amidation reaction, and a 5% - 50% piperidine DMF solution is added to deprotect the group; preferably, based on the amount of 2-CTC resin used, the amount of Fmoc-Glu(OtBu)-OH is 1 - 10 molar equivalents, and the amounts of HBTU and DIEA are 1 - 10 molar equivalents respectively;

[0025] Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-Trp-OH, Fmoc-Tyr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-D-Phe-OH, Fmoc-β-Ala-OH, Fmoc-Gly-OH and Fmoc-Gly-OH are added in sequence, and HOBt and DIEA are used as the catalysts for the amidation reaction each time; preferably, based on the amount of 2-CTC resin used, the amounts of Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-Trp-OH, Fmoc-Tyr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-D-Phe-OH, Fmoc-β-Ala-OH, Fmoc-Gly-OH and Fmoc-Gly-OH are 1 - 10 molar equivalents respectively, the amount of HOBt is 1 - 10 molar equivalents, and the amount of DIEA is 1 - 10 molar equivalents;

[0026] When adding 2-(acetythio)acetic acid, DIC and HOBt are used as the catalysts for the amidation reaction; preferably, based on the amount of 2-CTC resin used, the amount of 2-(acetythio)acetic acid is 1 - 10 molar equivalents, the amount of DIC is 1 - 10 molar equivalents, and the amount of HOBt is 1 - 10 molar equivalents.

[0027] The third object of the present invention is to provide a radionuclide complex of a somatostatin type 2 receptor inhibitor, which has a structure shown in the following formula II:

[0028]

[0029] Wherein, n is a natural number selected from 1 to 7, and the radionuclide Z is selected from 188 Re or 99m Tc;

[0030] In a further aspect, n is a natural number selected from 1 to 5;

[0031] Preferably, n = 2 or 3.

[0032] The fourth object of the present invention is to provide a preparation method of a radionuclide complex of a somatostatin type 2 receptor inhibitor as described above, including:

[0033] Using the somatostatin type 2 receptor inhibitor described in claim 1 or 2 as a raw material, adding potassium sodium tartrate tetrahydrate, SnCl2, Na 188 ReO4 or Na 99m TcO4, and carrying out a heating reaction in an acetic acid-sodium acetate buffer system to obtain the radionuclide complex of the somatostatin type 2 receptor inhibitor.

[0034] In a further aspect, the dosage of the somatostatin type 2 receptor inhibitor is 0.05 - 10 mg, the dosage of potassium sodium tartrate tetrahydrate is 10 - 50 mg; the dosage of SnCl2 is 0.1 - 10 mg, and the dosage of Na 188 ReO4 or Na 99m TcO4 is 37 - 3700 MBq; the pH of the acetic acid-sodium acetate buffer system is 4.0 - 6.0.

[0035] The fifth object of the present invention is to provide an application of the somatostatin type 2 receptor inhibitor as described above, or the radionuclide complex of the somatostatin type 2 receptor inhibitor as described above in the preparation of a SPECT / CT imaging agent or a tumor therapeutic agent;

[0036] Preferably, it is used in the preparation of a therapeutic agent for neuroendocrine tumors.

[0037] After adopting the above technical solutions, the present invention has the following beneficial effects compared with the prior art.

[0038] (1) The preparation method of the SSTR2 small molecule inhibitor described in the present invention is a solid-phase synthesis method, and the preparation process is simple and efficient, and it is easy to realize automation. The radionuclide-labeled SSTR2 small molecule inhibitor described in the present invention has a radionuclide of 188 Re, which can be obtained from tungsten rhenium (188 W- 188 is obtained from a Re generator, which is convenient to prepare and low in cost. 188 Re mainly emits β-rays and 15% γ-rays, with a half-life of 16.98 hours. The maximum energy of its β-rays is 2.12 MeV. Such high-energy β-rays have a maximum range of 10.4 mm in soft tissue and an average penetration depth of 3.1 mm, which is suitable for internal radiotherapy. Its γ-rays with an energy of 155 keV can also be used for SPECT imaging to monitor the in-vivo distribution of drugs and conduct pharmacokinetic studies. 188 Re-labeled compounds can be used for both treatment and SPECT imaging diagnosis. The SSTR2 small molecule inhibitor provided by the present invention can also be used for labeling with technetium-99m ( 99m Tc) for SPECT imaging.

[0039] (2) Based on D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH that specifically targets SSTR2, the present invention introduces S-Acetyl-MAG2-NH-(CH2)n-CO. On the one hand, it can achieve the labeling of radionuclide 188 Re or 99m Tc. The labeling method is simple, convenient, fast, with a high labeling rate and good stability. On the other hand, for NH-(CH2)n-CO, when n is a natural number selected from 1 to 7, it can moderately increase the lipophilicity of the whole compound, and at the same time, with an appropriate spatial structure, it can enhance the affinity with somatostatin receptor type 2, which is beneficial to improving the targeting of the drug.

[0040] As a preferred embodiment, the bifunctional chelating agent S-Acetyl-MAG2-β-Ala (acylmercaptoacetyl diglycine-β-alanine) is introduced to achieve the labeling of radionuclide 188 Re or 99m Tc. The labeling method is simple, convenient, fast, with a high labeling rate and good stability, and it has better targeting to the tumor tissue of neuroendocrine tumors. It can be labeled with 99m Tc for imaging diagnosis and labeled with 188 Re for treatment, providing a new idea for the integration of diagnosis and treatment of neuroendocrine tumors.

[0041] The following further describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. Description of the Drawings

[0042] The accompanying drawings, as part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention, but do not unduly limit the present invention. Obviously, the accompanying drawings in the following description are only some embodiments, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0043] Figure 1 In Example 2 of the present invention 188 TLC chromatogram of the Re-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH complex;

[0044] Figure 2 In Test Example 1 of the present invention 188 Stability analysis results of the Re-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH complex;

[0045] Figure 3 In Test Example 2 of the present invention 188 SPECT imaging results of the Re-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH complex in animals, after injection of 188 Re-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH, and the direction indicated by the arrow is the tumor tissue.

[0046] It should be noted that these drawings and textual descriptions are not intended to limit the scope of the concept of the present invention in any way, but to illustrate the concept of the present invention to those skilled in the art by referring to specific embodiments. Detailed implementation manners

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0048] Example 1: Preparation of S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (n = 2)

[0049] Synthesized by solid-phase synthesis method, and all raw materials used are commercially available products. The specific synthesis steps are as follows:

[0050] Using 2-CTC resin as the starting material, add 2 molar equivalents of Fmoc-Thr(tBu)-OH and use 4 molar equivalents of DIEA; add 5% - 50% piperidine DMF solution to deprotect; add 2 molar equivalents of Fmoc-Glu(OtBu)-OH and use 2 molar equivalents of HBTU and DIEA for amidation reaction; add 5% - 50% piperidine DMF solution to deprotect; sequentially add 2 molar equivalents of Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-Trp-OH, Fmoc-Tyr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-D-Phe-OH, Fmoc-β-Ala-OH, Fmoc-Gly-OH and Fmoc-Gly-OH, and use 2 molar equivalents of HOBt and 4 molar equivalents of DIEA for each amidation reaction; add 2 molar equivalents of 2-(acetythio)acetic acid and use 2 molar equivalents of DIC and 2 molar equivalents of HOBt for amidation; use TFA / Tis / 3-Mercaptopropionic acid mixed solution to remove the remaining protecting groups and 2-CTC resin; use I2 for cyclization to obtain the crude peptide.

[0051] The obtained crude peptide was purified by Prep-HPLC. The crude peptide was dissolved in 20% TFA aqueous solution. The purification conditions were: Luna C18 column, 20 mL / min, 0.075% TFA in H2O (A), CH3CN (B); 0 - 60 min (B): 20 - 50%. The final product S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH with a purity of 98.6% was obtained.

[0052] Example 2: 188 Preparation of Re-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (n = 2) complex

[0053] Dissolve 3 mg of S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (prepared in Example 1) and 20 mg of potassium sodium tartrate tetrahydrate in 1 M acetic acid-sodium acetate buffer at pH 5.8, and successively add 0.1 M dilute hydrochloric acid solution containing 3 mg of stannous chloride dihydrate, and 370 MBq of Na 188 ReO4 eluate. After thorough mixing, react in a boiling water bath for 20 minutes, cool to room temperature, and then add 1 ml of physiological saline containing 15 mg / ml of ascorbic acid, and mix well to obtain the target compound 188 Re-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH. Determine its radiochemical purity to be greater than 98% by Radio-HPLC or Radio-TLC

[0054] Radio-HPLC conditions: Luna Omega C18 column, 1.0 ml / min, 0.1% TFA in H2O (A), 0.1% TFA in CH3CN (B); 0 - 10 min (B): 20 - 50%

[0055] Radio-TLC conditions: The stationary phase is a GF254 thin-layer silica gel plate, and the mobile phases are (1) acetone; (2) methanol: 1 M ammonium acetate mixed solution (1:1)

[0056] Figure 1 The TLC map of the Re-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH complex determined by Radio-TLC is shown in 188 Figure

[0057] Test Example 1: 188 In vitro stability analysis of Re-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH

[0058] The Re-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH sample obtained in Example 2 was stored at a constant temperature of 30°C. Samples were taken at 2 h, 24 h, 48 h, and 72 h after labeling to determine its radiochemical purity. The results are as follows 188 shown in Figure 2As shown, the results show 188 Re-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH has good stability.

[0059] Test Example 2: 188 SPECT imaging experiment of Re-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH in animals

[0060] C57BL / 6 male nude mice with AR42J cells implanted in the right axilla were selected and injected via the tail vein. 188 Re-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (prepared in Example 2) was anesthetized with 1.5% isoflurane / oxygen and then fixed for SPECT / CT imaging. The results are as follows Figure 3 As shown, the results showed that the uptake of axillary tumor tissue was obvious and was mainly excreted through the kidneys, while no obvious uptake was observed in other organs.

[0061] Embodiment 3: 99m Preparation of Tc-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH(n=2) Complex

[0062] 5 mg of S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (prepared in Example 1) and 30 mg of potassium sodium tartrate tetrahydrate were dissolved in 1 M acetic acid-sodium acetate buffer at pH 5.5, and 0.1 M dilute hydrochloric acid solution containing 0.5 mg of stannous chloride dihydrate and 740 MBq of Na 99m After the TcO4 eluent is fully mixed, react in a boiling water bath for 20 minutes, cool to room temperature, then add 1 ml of saline containing 15 mg / ml ascorbic acid, mix well to obtain the target compound 99m Tc-S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH, the radiochemical purity was greater than 98% as determined by Radio-TLC.

[0063] Embodiment 4: 188Preparation of Re-MAG2-GABA-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH(n=3) complex

[0064] 10 mg of S-Acetyl-MAG2-GABA-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH and 50 mg of potassium sodium tartrate tetrahydrate were dissolved in 1 M acetic acid-sodium acetate buffer at pH 6.0, and 0.1 M dilute hydrochloric acid solution containing 10 mg of stannous chloride dihydrate and 3700 MBq of Na 188 After ReO4 eluent is fully mixed, react in a boiling water bath for 20 minutes, cool to room temperature, then add 1 ml of saline containing 15 mg / ml ascorbic acid, mix well to obtain the target compound 188 Re-S-Acetyl-MAG2-GABA-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH, the radiochemical purity of which was determined by Radio-TLC was greater than 98%.

[0065] Embodiment 5: 188 Preparation of Re-S-Acetyl-MAG2-NH(CH2)5CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH(n=5) Complex

[0066] 3 mg of S-Acetyl-MAG2-NH(CH2)5CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH and 25 mg of potassium sodium tartrate tetrahydrate were dissolved in 1 M acetic acid-sodium acetate buffer at pH 5.8, and 0.1 M dilute hydrochloric acid solution containing 5 mg of stannous chloride dihydrate and 740 MBq of Na 188 After ReO4 eluent is fully mixed, react in a boiling water bath for 20 minutes, cool to room temperature, then add 1 ml of saline containing 15 mg / ml ascorbic acid, mix well to obtain the target compound 188 Re-S-Acetyl-MAG2-NH(CH2)5CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH, the radiochemical purity was greater than 98% as determined by Radio-TLC.

[0067] Embodiment 6: 188Preparation of Re-S-Acetyl-MAG2-NH(CH2)7CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH(n=7) Complex

[0068] 1 mg of S-Acetyl-MAG2-NH(CH2)7CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH and 10 mg of potassium sodium tartrate tetrahydrate were dissolved in 1 M acetic acid-sodium acetate buffer at pH 5.0, and 0.1 M dilute hydrochloric acid solution containing 1.5 mg of stannous chloride dihydrate and 1110 MBq of Na 188 After ReO4 eluent is fully mixed, react in a boiling water bath for 20 minutes, cool to room temperature, then add 1 ml of saline containing 15 mg / ml ascorbic acid, mix well to obtain the target compound 188 Re-S-Acetyl-MAG2-NH(CH2)7CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH, the radiochemical purity was 95% as determined by Radio-TLC.

[0069] Embodiment 7: 99m Preparation of Tc-S-Acetyl-MAG2-GABA-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH(n=3) Complex

[0070] 1 mg of S-Acetyl-MAG2-GABA-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH and 10 mg of potassium sodium tartrate tetrahydrate in 1 M acetic acid-sodium acetate buffer at pH 6.0 were added with 0.1 M dilute hydrochloric acid solution containing 0.5 mg of stannous chloride dihydrate and 74 MBq of Na 99m After the TcO4 eluent is fully mixed, react in a boiling water bath for 10 minutes, cool to room temperature, then add 1 ml of saline containing 15 mg / ml ascorbic acid and mix well to obtain the target compound. 99m Tc-S-Acetyl-MAG2-GABA-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH, the radiochemical purity was greater than 98% as determined by Radio-TLC.

[0071] Embodiment 8: 99mPreparation of Tc-S-Acetyl-MAG2-NH(CH2)5CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (n = 5) Complex

[0072] Into a 1 M acetic acid-sodium acetate buffer solution at pH 4.0 containing 0.05 mg of S-Acetyl-MAG2-NH(CH2)5CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH and 10 mg of potassium sodium tartrate tetrahydrate, a 0.1 M dilute hydrochloric acid solution containing 0.1 mg of stannous chloride dihydrate and 37 MBq of Na 99m TcO4 eluate were successively added. After thorough mixing, the reaction was carried out in a boiling water bath for 10 minutes, cooled to room temperature, and then 1 ml of physiological saline containing 15 mg / ml of ascorbic acid was added and mixed evenly to obtain the target compound 99m For Tc-S-Acetyl-MAG2-NH(CH2)5CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH, its radiochemical purity was determined by Radio-TLC to be greater than 98%.

[0073] Example 9: 99m Preparation of Tc-S-Acetyl-MAG2-NH(CH2)7CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (n = 7) Complex

[0074] Dissolve 5 mg of S-Acetyl-MAG2-NH(CH2)7CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH and 30 mg of potassium sodium tartrate tetrahydrate in a 1 M acetic acid-sodium acetate buffer solution at pH 4.5, and successively add a 0.1 M dilute hydrochloric acid solution containing 1 mg of stannous chloride dihydrate and 370 MBq of Na 99m TcO4 eluate. After thorough mixing, the reaction was carried out in a boiling water bath for 10 minutes, cooled to room temperature, and then 1 ml of physiological saline containing 15 mg / ml of ascorbic acid was added and mixed evenly to obtain the target compound 99m For Tc-S-Acetyl-MAG2-NH(CH2)7CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH, its radiochemical purity was determined by Radio-TLC to be 96%.

[0075] Example 10: 99mPreparation of Tc-S-Acetyl-MAG3-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (n = 1) Complex

[0076] Dissolve 5 mg of S-Acetyl-MAG3-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH and 10 mg of potassium sodium tartrate tetrahydrate in 1 M acetic acid-sodium acetate buffer solution with pH 5.5. Then, successively add 0.1 M dilute hydrochloric acid solution containing 0.5 mg of stannous chloride dihydrate and 3700 MBq of Na 99m TcO4 eluate. After thorough mixing, react in a boiling water bath for 10 minutes, cool to room temperature, and then add 1 ml of physiological saline containing 15 mg / ml of ascorbic acid and mix well to obtain the target compound 99m For Tc-S-Acetyl-MAG3-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH, its radiochemical purity was determined to be greater than 98% by Radio-TLC

[0077] Example 11: 188 Preparation of Re-S-Acetyl-MAG3-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (n = 1) Complex

[0078] Dissolve 6 mg of S-Acetyl-MAG3-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH and 40 mg of potassium sodium tartrate tetrahydrate in 1 M acetic acid-sodium acetate buffer solution with pH 5.8. Then, successively add 0.1 M dilute hydrochloric acid solution containing 7 mg of stannous chloride dihydrate and 2220 MBq of Na 188 ReO4 eluate. After thorough mixing, react in a boiling water bath for 20 minutes, cool to room temperature, and then add 1 ml of physiological saline containing 15 mg / ml of ascorbic acid and mix well to obtain the target compound 188 For Re-S-Acetyl-MAG3-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH, its radiochemical purity was determined to be 97% by Radio-TLC

[0079] Comparative Example 1: 188Preparation of Re-S-Acetyl-MAG2-NH(CH2)9CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (n = 9) Complex

[0080] Prepared according to the methods of Example 1 and Example 2 188 Re-S-Acetyl-MAG2-NH(CH2)9CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH. The difference is that the raw material Fmoc-β-Ala-OH in Example 1 was changed to Fmoc-NH(CH2)9COOH, and the S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH in Example 2 was changed to S-Acetyl-MAG2-NH(CH2)9CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH.

[0081] Comparative Example 2: 188 Re-S-Acetyl-MAG2-NH(CH2) 11 Preparation of Re-S-Acetyl-MAG2-NH(CH2)

[0082] Prepared according to the methods of Example 1 and Example 2 188 Re-S-Acetyl-MAG2-NH(CH2) 11 CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH. The difference is that the raw material Fmoc-β-Ala-OH in Example 1 was changed to Fmoc-NH(CH2) 11 COOH, and the S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH in Example 2 was changed to S-Acetyl-MAG2-NH(CH2) 11 CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH.

[0083] Comparative Example 3: 99mPreparation of Tc-S-Acetyl-MAG2-NH(CH2)9CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (n = 9) Complex

[0084] Prepared by referring to the methods of Example 1 and Example 3 99m Tc-S-Acetyl-MAG2-NH(CH2)9CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH. The difference is that the raw material Fmoc-β-Ala-OH in Example 1 is changed to Fmoc-NH(CH2)9COOH, and S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH in Example 3 is changed to S-Acetyl-MAG2-NH(CH2)9CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH.

[0085] Comparative Example 4: 99m Tc-S-Acetyl-MAG2-NH(CH2) 11 Preparation of Tc-S-Acetyl-MAG2-NH(CH2)

[0086] Prepared by referring to the methods of Example 1 and Example 3 99m Tc-S-Acetyl-MAG2-NH(CH2) 11 CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH. The difference is that the raw material Fmoc-β-Ala-OH in Example 1 is changed to Fmoc-NH(CH2) 11 COOH, and S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH in Example 3 is changed to S-Acetyl-MAG2-NH(CH2) 11 CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH.

[0087] Test Example 3: 188 Re-S-Acetyl-MAG2-NH(CH2) nIn vitro stability test of CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (n = 1, 2, 3, 5, 7, 9, 11)

[0088] Referring to Test Example 1, the 188 Re-S-Acetyl-MAG2-NH(CH2) n samples of CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (n = 1, 2, 3, 5, 7, 9, 11) obtained in Example 11, Example 2, Example 4, Example 5, Example 6 and Comparative Example 1, Comparative Example 2 were stored at a constant temperature of 30 °C. Samples were taken at 2 h, 24 h, 48 h, and 72 h after labeling to measure their radiochemical purity. The results are shown in Table 1 below.

[0089] Table 1 Results of in vitro stability test

[0090]

[0091]

[0092] As can be seen from the results in Table 1 above, for the radionuclide 188 Re complex prepared by the present invention, when n = 1 - 7, the in vitro stability is good, and the radiochemical purity is maintained above 90% within 72 hours; when n = 1 - 5, the radiochemical purity is maintained above 93% within 72 hours; especially when n = 2 or 3, the radiochemical purity is maintained above 95% within 72 hours, and the stability is better. When n > 7, the in vitro stability decreases, and the radiochemical purity drops below 90% after 48 hours.

[0093] Test Example 4: 99m Tc-S-Acetyl-MAG2-NH(CH2) n SPECT imaging experiment of CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (n = 1, 2, 3, 5, 7, 9, 11) in animals

[0094] Referring to Test Example 2, male C57BL / 6 nude mice bearing tumors implanted with AR42J cells with a tumor diameter of about 10 mm were used. The 99m Tc-S-Acetyl-MAG2-NH(CH2) nSamples of CO-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH (n = 1, 2, 3, 5, 7, 9, 11) were injected via the tail vein. After 2 hours, the animals were anesthetized and fixed with 1.5% isoflurane / oxygen, and then SPECT / CT imaging was performed to measure the tumor / muscle radioactivity uptake ratio. The results are shown in Table 2 below.

[0095] Table 2 Results of SPECT imaging experiment

[0096]

[0097]

[0098] As can be seen from the results in Table 2 above, for the radionuclide 99m Tc complexes prepared by the present invention, when n = 1 - 7, the tumor / muscle radioactivity uptake ratio is relatively high. Especially when n = 2 or 3, the target / background ratio is the highest, indicating good tumor tissue targeting; while when n > 7, the tumor / muscle radioactivity uptake ratio decreases significantly, indicating a decline in tumor tissue targeting.

[0099] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention has been disclosed as above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art of this patent, without departing from the scope of the technical solution of the present invention, may make some modifications or variations equivalent to the equivalent embodiments by using the technical content prompted above. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the present invention.

Claims

1. A somatostatin type 2 receptor inhibitor, characterized in that, It has the structure shown in Formula I as follows: Wherein, n is selected from natural numbers from 2 to 7.

2. The somatostatin type 2 receptor inhibitor according to claim 1, characterized in that, n is selected from natural numbers from 2 to 5.

3. The somatostatin type 2 receptor inhibitor according to claim 1, characterized in that, n = 2 or 3.

4. A preparation method of a somatostatin type 2 receptor inhibitor S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo (Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH, characterized in that, The preparation method includes: Step (1): The solid-phase carrier resin is sequentially coupled with the N-terminus and side chains both protected according to the amino acid sequence of β-Ala-D-Phe-(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH, and then coupled with S-Acetyl-MAG2 to obtain a linear resin peptide; Step (2): Take the linear peptide resin obtained in Step (1), add a cleavage solution to remove the protecting groups and cleave the resin to obtain a linear peptide; Step (3): Oxidize the linear peptide with an oxidant to obtain a crude peptide.

5. The preparation method according to claim 4, characterized in that, It includes: Using CTC resin as the starting material, sequentially adding Fmoc-Thr(tBu)-OH and Fmoc-Glu(OtBu)-OH, and respectively carrying out amidation reactions and deprotecting; Then sequentially adding Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-Trp-OH, Fmoc-Tyr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-D-Phe-OH, Fmoc-β-Ala-OH, Fmoc-Gly-OH and Fmoc-Gly-OH, and respectively carrying out amidation reactions; Then add 2-(acetythio)acetic acid to carry out an amidation reaction, and then remove the remaining protecting groups and 2-CTC resin; Use I2 for cyclization to obtain S-Acetyl-MAG2-β-Ala-D-Phe-Cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr-OH.

6. The preparation method according to claim 5, characterized in that, When adding Fmoc-Thr(tBu)-OH, use DIEA as the catalyst for the amidation reaction, and add a 5% - 50% piperidine DMF solution for deprotection; When adding Fmoc-Glu(OtBu)-OH, use HBTU and DIEA as the catalysts for the amidation reaction, and add a 5% - 50% piperidine DMF solution for deprotection; When sequentially adding Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-Trp-OH, Fmoc-Tyr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-D-Phe-OH, Fmoc-β-Ala-OH, Fmoc-Gly-OH and Fmoc-Gly-OH, use HOBt and DIEA as the catalysts for each amidation reaction; When adding 2-(acetythio)acetic acid, use DIC and HOBt as the catalysts for the amidation reaction.

7. The preparation method according to claim 6, characterized in that, Based on the amount of 2-CTC resin, the amount of Fmoc-Thr(tBu)-OH is 1 - 10 molar equivalents, and the amount of DIEA is 1 - 10 molar equivalents.

8. The preparation method according to claim 6, characterized in that, Based on the amount of 2-CTC resin, the amount of Fmoc-Glu(OtBu)-OH is 1 - 10 molar equivalents, and the amounts of HBTU and DIEA are 1 - 10 molar equivalents respectively.

9. The preparation method according to claim 6, characterized in that, Based on the amount of 2-CTC resin, the amounts of Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-Trp-OH, Fmoc-Tyr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-D-Phe-OH, Fmoc-β-Ala-OH, Fmoc-Gly-OH and Fmoc-Gly-OH are 1 - 10 molar equivalents respectively, the amount of HOBt is 1 - 10 molar equivalents, and the amount of DIEA is 1 - 10 molar equivalents.

10. The preparation method according to claim 6, characterized in that, Based on the amount of 2-CTC resin, the amount of 2-(acetythio)acetic acid is 1 - 10 molar equivalents, the amount of DIC is 1 - 10 molar equivalents, and the amount of HOBt is 1 - 10 molar equivalents.

11. A radionuclide complex of a somatostatin type 2 receptor inhibitor, characterized in that,It has the structure shown in Formula II below: Among them, n is a natural number selected from 2 to 7, and the radionuclide Z is selected from 188 Re or 99m Tc.

12. The radionuclide complex of the somatostatin type 2 receptor inhibitor according to claim 11, characterized in that, n is selected from natural numbers from 2 to 5.

13. The radionuclide complex of the somatostatin type 2 receptor inhibitor according to claim 11, characterized in that, n = 2 or 3.

14. A method for preparing a radionuclide complex of the somatostatin type 2 receptor inhibitor according to any one of claims 11-13, characterized in that, Comprising: Using the somatostatin type 2 receptor inhibitor according to any one of claims 1 to 3 as a raw material, adding potassium sodium tartrate tetrahydrate, SnCl2, Na 188 ReO4 or Na 99m TcO4, and carrying out a heating reaction in an acetic acid-sodium acetate buffer system to obtain the radionuclide complex of the somatostatin type 2 receptor inhibitor.

15. The preparation method according to claim 14, characterized in that, The dosage of the somatostatin type 2 receptor inhibitor is 0.05 - 10 mg, the dosage of potassium sodium tartrate tetrahydrate is 10 - 50 mg; the dosage of SnCl2 is 0.1 - 10 mg, Na 188 ReO4 or Na 99m The dosage of TcO4 is 37 - 3700 MBq; the pH of the acetic acid - sodium acetate buffer system is 4.0 - 6.

0.

16. Use of a somatostatin type 2 receptor inhibitor according to any one of claims 1-3, or a radionuclide complex of the somatostatin type 2 receptor inhibitor according to any one of claims 11-13 in the preparation of a therapeutic agent for treating neuroendocrine tumors.

17. Use of a radionuclide complex of the somatostatin type 2 receptor inhibitor according to any one of claims 11-13 in the preparation of a SPECT / CT imaging agent.

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