Targeting peptide, conjugate thereof, preparation method therefor, and use thereof

Abstract

Provided are a peptide analog or derivative of somatostatin (SST), which is capable of binding to somatostatin receptors (SSTRs), especially the SSTR2 subtype, with high affinity. In addition, the polypeptide can be used in a labeled or unlabeled form for diagnosing or treating SSTR-positive lesions and, after radiolabeling, exhibits better in vivo pharmacokinetic behavior than known somatostatin analogs such as TATE (Tyr3-octreotate), with strong tumor specificity and very low uptake in other non-target organs except the kidney.

Description

A targeting peptide and its conjugates, preparation method and uses

[0001] Citation of relevant applications

[0002] This application claims priority and benefits to Chinese Patent Application No. 202510127526.4, filed with the State Intellectual Property Office of the People's Republic of China on January 27, 2025, and Chinese Patent Application No. 202511430645.3, filed with the State Intellectual Property Office of the People's Republic of China on September 30, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of somatostatin, and more particularly to a targeting peptide or a pharmaceutically acceptable salt thereof used as an SSTR2 regulator / SSTR2 ligand, an SSTR2 binding molecule comprising said targeting peptide, methods for preparing said targeting peptide and their applications, especially to the regulation and targeting of the somatostatin receptor SSTR2. Background Technology

[0004] Somatostatin (SST) is a multifunctional polypeptide hormone produced by brain, gastrointestinal, retinal, immune and neuroendocrine cells, and pancreatic D cells in response to various stimuli. As an endogenous inhibitory regulator of different cellular functions, SST regulates processes such as development, proliferation, metabolism, secretion, and neural activity. The somatostatin receptor (SSTR) is widely expressed throughout the body and has five subtypes, SSTR1-5, with SSTR2 being the most extensively studied. SSTR affects intracellular cAMP concentration by regulating the activity of adenylate cyclase (AC), thereby transmitting exogenous signals into the cell and triggering various cellular signaling pathways. SSTR participates in the secretion regulation of multiple hormones and is associated with tumor growth and proliferation. Researchers have found high expression of SSTR in various tumor tissues, with somatostatin receptor 2 (SSTR2) showing the highest expression. To improve the stability of endogenous ligands and prolong their half-life, researchers have developed several somatostatin analogs (such as somatostatin-targeting peptides) containing agonists and antagonists. The agonist, upon binding to the cell surface receptor, causes a conformational change in the receptor, activating the associated G protein. The activated SSTR2 triggers the dissociation of the G protein heterotrimer into Gα and Gβγ subunits, inhibiting adenylate cyclase activity and reducing intracellular cyclic adenine nucleotide (cAMP) levels. Low concentrations of cAMP inhibit protein kinase activity, thereby potentially preventing oncogene activation and suppressing tumors. Furthermore, activated SSTR2 may also activate tyrosine protein phosphatase, inhibiting tyrosine phosphorylation and the phosphatidylinositol 3-kinase (PI3K) / Akt pathway, inhibiting cytoplasmic calcium...2+ Refluxing (Endocr.Rev.2025,46(1),26-42). SSTR antagonists also bind to cell surface receptors, but unlike agonists which bind to receptors and endocytose into the cell, antagonists hardly endocytose after binding to receptors, remaining only on the cell surface. They do not cause biological effects themselves, but can block the binding of agonists to receptors, thereby inhibiting agonist-mediated biological effects. These analogs are usually cyclic octapeptides, such as octreotide, the first agonist peptide analog approved by the FDA.

[0005] SSTR2 is overexpressed in various solid tumors, including neuroendocrine tumors, thyroid cancer, breast cancer, gastric cancer, liver cancer, and lung cancer. Given its widespread expression and important role in tumors, SSTR2 has become a crucial target for tumor imaging and therapy. Currently, most SSTR2 drugs under development focus on peptide-isotope conjugates and synthetic peptides. Over the past two decades, peptide receptor radionuclide therapy (PRRT) has rapidly expanded its clinical application as a very promising treatment for neuroendocrine tumors (NETs). By binding radioactive metals to somatostatin receptor (SSTR) ligands, radiation can be precisely delivered to cancer cells regardless of whether the ligand is internalized into the cell, thereby killing cancer cells, inhibiting tumor proliferation, and avoiding the side effects and radiation damage to normal tissue cells associated with traditional external beam radiotherapy. The emergence of therapeutic somatostatin radiopharmaceuticals in clinical practice has undoubtedly improved patients' quality of life and survival rates. With continuous development in this field, novel and improved molecular structures have been provided. Based on the research and development of SSTR2 receptor ligands, this strategy is now applied to a wider range of clinical indications, including renal cell carcinoma, small cell lung cancer, breast cancer, non-Hodgkin's lymphoma, medullary thyroid carcinoma, pheochromocytoma, and paraganglioma. For example, small cell lung cancer (SCLC) is a neuroendocrine malignancy with a very poor prognosis, accounting for about 13% to 15% of all lung cancer cases. It is prone to metastasis and progresses rapidly, with high drug resistance and recurrence rates. Current treatment regimens offer very limited survival benefits to patients. Although immunotherapy combined with chemotherapy and anti-angiogenic therapy have improved the survival prognosis of SCLC patients in recent years, the efficacy is still limited, and only some patients benefit. Immunohistochemistry shows that up to 50% of SCLC tumors are SSTR2 positive (Mol. Cancer Ther. 2023, 22(12), 1434-1443). Peptide-isotope conjugates targeting SSTR2 have gradually shown great potential to expand into indications for neuroendocrine malignancies such as small cell lung cancer.

[0006] Currently, most research on targeted radiopharmaceuticals based on SSTR2 agonists or antagonists is in the clinical or preclinical research stage (Pharmaceuticals, 2023, 16, 674). Researchers have developed, for example, Novartis's...177 Lu is the tag for DOTA-TATE (Lutathera). 225 Ac-marked DOTA-TATE and 177 Numerous clinical studies have been conducted on Lu-labeled DOTA-JR11 targeting SSTR, particularly SSTR2-related neuroendocrine tumors (including extensive-stage small cell lung cancer). However, currently only Novartis' Lutathera has received FDA approval in 2018 for the treatment of gastrointestinal and pancreatic neuroendocrine tumors. This approval was based on two pivotal Phase III clinical trials, which showed that Lutathera treatment resulted in tumor shrinkage or complete disappearance in some patients, a 19.9-month extension of progression-free survival compared to the control group, a 79% reduction in the risk of disease progression or death, good safety profile, and significant improvements in health-related quality of life for these patients (N. Engl. J. Med. 2017, 376, 125-135). To further improve patient survival and mortality risk, more SSTR2-targeting agents with higher safety profiles and broader indications are still needed. Summary of the Invention

[0007] This application provides an improved somatostatin analog that specifically targets and regulates SSTR2, exhibiting significantly improved binding affinity, pharmacokinetics, and biodistribution. This application also provides an SSTR2-binding molecule (e.g., a peptide-nucleoside conjugate) comprising this somatostatin analog. Furthermore, this application provides methods for preparing the somatostatin analog and the SSTR2-binding molecule comprising it, as well as their applications.

[0008] Somatostatin-targeting peptides and their pharmaceutically acceptable salts

[0009] In one aspect, this application provides a somatostatin-targeting peptide or a pharmaceutically acceptable salt thereof, the somatostatin receptor-targeting peptide having the structure shown in formula (I):

[0010] HD-Phe-ring [Cys-Xaa] 1 -Xaa 2 -Xaa 3 -Thr-Cys]-Xaa 4 Formula (I),

[0011] Among them, Xaa 1 It consists of α or β amino acid residues of type L or D, and has the structure of formula 1a:

[0012] Where n is selected from 0 or 1, preferably 0;

[0013] R 11Selected from phenyl, 4-hydroxyphenyl, or 5- to 10-membered heteroaryl groups, wherein the phenyl, 4-hydroxyphenyl, or 5- to 10-membered heteroaryl group may optionally be converted by one or more R groups. 0 Instead, the R 0 Each is independently selected from C 1-6 Alkyl, C 1-6 Alkoxy, CN, OH, halogen, C 1-6 Halogenated alkyl groups, NH2, -NCH2CH3, -N(CH3)2, -B(OH)2, -PO(OH)2, -SO(OH)2, -O-PO(OH)2;

[0014] R 12 Selected from H or C 1-3 Alkyl, preferably H, methyl, ethyl, or isopropyl;

[0015] Z is selected from one or more Cs. 1-3 alkyl or halogen-substituted C 1-4 Alkyl groups (preferably, for example, -CH2-, -CH(CH3)-, -CH2CH2-);

[0016] Among them, Xaa 2 It consists of L or D type (preferably D type) α amino acid residues and has the structure of Formula 1b:

[0017] Among them, R 21 Selected from cyclohexanediol groups, wherein the cyclohexanediol group may optionally be C 1-6 Alkyl, C 1-6 One or more substitutions of alkoxy, CN, OH, halogen, or amino;

[0018] Among them, Xaa 3 It consists of α-amino acid residues of type L or D (preferably type L) and has the structure of formula 1c:

[0019] Among them, R 31 Selected from substituted or unsubstituted C 1-6 Aminoalkyl or 5-6 membered heterocyclic alkyl, wherein C 1-6 The aminoalkyl or 5-6 membered heterocyclic alkyl group is optionally C 1-4 One or more substitutions of alkyl, OH, amino, or halogen;

[0020] Among them, Xaa 4 Selected from Thr-OH or Thr-ol;

[0021] The condition is that when Xaa 4 When it is Thr-ol, R 11Selected from phenyl, wherein the phenyl group is substituted by one or more of NH2, -B(OH)2, -PO(OH)2, -SO(OH)2, -O-PO(OH)2; or, when R 31 Selected from C 1-6 Aminoalkyl, Xaa 2 For Trp, R 11 When R is selected from phenyl, 11 It is substituted by at least one or more of NH2, -B(OH)2, -PO(OH)2, -SO(OH)2, and -O-PO(OH)2; or, when R 31 Selected from C 1-6 Aminoalkyl, Xaa 2 For Trp, R 11 When R is selected from 4-hydroxyphenyl, 11 Substituents R 0 Replace, and the R 0 Not I.

[0022] In some implementations, Xaa 1 It is an L-type α or β amino acid residue, preferably an L-type α amino acid residue.

[0023] In some implementations, Xaa in Equation 1a 1 In the middle, R 11 The phenyl, 4-hydroxyphenyl, or 5- to 10-membered heteroaryl group may be selected from phenyl, 4-hydroxyphenyl, or 5- to 10-membered heteroaryl group, wherein the phenyl, 4-hydroxyphenyl, or 5- to 10-membered heteroaryl group is optionally converted by one or more R 0 Instead, the R 0 Each is independently selected from C 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 One or more of the following: haloalkyl, OH, halogen, NH2, -N(CH3)2, -B(OH)2, -PO(OH)2, or -O-PO(OH)2; preferably, the phenyl and 5- to 10-membered heteroaryl groups can be C 1-6 Alkyl, C 1-6 One or more of the following substitutions: alkoxy, OH, halogen, NH2, -N(CH3)2, -B(OH)2, -O-PO(OH)2.

[0024] In some implementations, Xaa in Equation 1a 1 In, the R 0 Each was independently selected from C 1-4 Alkyl, C 1-4 Alkoxy, C 1-4 Halogenated alkyl, OH, halogen, NH2, -N(CH3)2, -B(OH)2 or -O-PO(OH)2.

[0025] In some implementations, Xaa in Equation 1a 1 In the middle, R 11 The phenyl group may be selected from phenyl groups, and the phenyl group has at least one R. 0 , where R 0 Each was independently selected from C 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 The alkyl halogroup, NH2, -N(CH3)2, -B(OH)2, -SO(OH)2, -PO(OH)2 or -O-PO(OH)2, more preferably selected from NH2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2, and even more preferably selected from -B(OH)2, -PO(OH)2 or -O-PO(OH)2.

[0026] In some implementations, Xaa in Equation 1a 1 In the middle, R 11 The phenyl group may be selected from phenyl groups, and the phenyl group has at least one R. 0 , of which at least one R 0 Substitution occurs at the para-position of the phenyl group. In some embodiments, Xaa of formula 1a... 1 In the middle, R 11 The phenyl group may be selected from phenyl groups, and the phenyl group has at least one R. 0 , of which at least one R 0 At least at the para position of the phenyl group, preferably at the para position of the phenyl group, there is a substituent selected from methyl, ethyl, amino, CF3, F, Cl, Br, NH2, -N(CH3)2, -B(OH)2, -SO(OH)2, -PO(OH)2 or -O-PO(OH)2.

[0027] In some implementations, Xaa in Equation 1a 1 In the middle, R 11 The phenyl group may be selected from phenyl groups, and the phenyl group has at least one R. 0 , where R 0 Each is independently selected from -NH2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2, and other definitions are the same as those defined in this article.

[0028] In some implementations, Xaa 4 For Thr-ol, R 11 The phenyl group is selected from phenyl, and the phenyl group is substituted by one or more of -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2, especially by one or more of -B(OH)2, -PO(OH)2 or -O-PO(OH)2.

[0029] In some implementations, R in formula 1a 11 In this context, the 5-10 nucleotide heteroaryl group is preferably a 6-10 nucleotide heteroaryl group, comprising 1, 2, 3, or 4 heteroatoms selected from S, O, or N as ring atoms, preferably comprising 1 or 2 heteroatoms selected from O or N as ring atoms, more preferably comprising 1 or 2 N as ring atoms, wherein the heteroaryl group is optionally surrounded by one or more R atoms. 0 replace.

[0030] In some implementations, R in formula 1a 11 In this context, the 5-10 aryl group may preferably be optionally surrounded by one or more R groups. 0 The following groups are substituted: pyridyl, pyridinyl, pyrimidinyl, benzopyridyl, pyrrolopyridyl, more preferably optionally substituted with one or more R groups. 0 The following groups may be substituted: pyridyl, pyridinyl, pyrimidinyl, pyrazinyl, quinolinyl, isoquinolinyl, pyrrolo[2,3-b]pyridinyl, or pyrrolo[2,3-c]pyridinyl (the heteroaryl group specifically includes, for example, pyridyl, pyrimidinyl, pyrazinyl, quinolinyl, isoquinolinyl, pyrrolo[2,3-b]pyridinyl, or pyrrolo[2,3-c]pyridinyl), and other definitions are the same as those defined herein.

[0031] In some implementations, R 11 Optional, can be selected by one or more R 0 Replacement The R 0 Each was independently selected from C 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl, CN, OH, halogen, NH2, -NCH2CH3, -N(CH3)2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2.

[0032] In some implementations, R 11 Optional, can be selected by one or more R 0 Replacement The R 0 Each was independently selected from C 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl groups, CN, OH, halogen, NH2, -NCH2CH3, -N(CH3)2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2, preferably C. 1-4 Alkyl, C1-4 Alkoxy, C 1-4 Halogenated alkyl, OH, halogen, NH2, -N(CH3)2, -B(OH)2 or -O-PO(OH)2, more preferably methyl, ethyl, isopropyl, methoxy, ethoxy, CF3, OH, F, Cl, Br, NH2, -N(CH3)2, -B(OH)2 or -O-PO(OH)2.

[0033] In some implementations, R 11 Optional The R 0 Each was independently selected from C 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl groups, CN, OH, halogen, NH2, -NCH2CH3, -N(CH3)2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2, preferably C. 1-4 Alkyl, C 1-4 Alkoxy, C 1-4 Halogenated alkyl, OH, halogen, NH2, -N(CH3)2, -B(OH)2 or -O-PO(OH)2, more preferably methyl, ethyl, isopropyl, methoxy, ethoxy, CF3, OH, F, Cl, Br, NH2, -N(CH3)2, -B(OH)2 or -O-PO(OH)2.

[0034] In some implementations, R 11 Optional The R 0 Selected from C 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Haloalkyl, CN, halogen, NH2, -NCH2CH3, -N(CH3)2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2, preferably C 1- 4-alkyl, C 1-4 Alkoxy, C 1-4 Halogenated alkyl, OH, halogen, NH2, -N(CH3)2, -B(OH)2 or -O-PO(OH)2, more preferably NH2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2, for example NH2, -B(OH)2, -PO(OH)2 or -O-PO(OH)2.

[0035] In some implementations, R 11 Optional The R0 Each was independently selected from C 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl groups, CN, OH, halogen, NH2, -NCH2CH3, -N(CH3)2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2, preferably C. 1-4 Alkyl, C 1-4 Alkoxy, C 1-4 Halogenated alkyl, OH, halogen, NH2 or -N(CH3)2, more preferably methyl, ethyl, isopropyl, methoxy, ethoxy, -CF3, OH, F, Cl, Br, NH2 or -N(CH3)2, most preferably methyl, ethyl, methoxy, ethoxy, -CF3, OH, F, Cl or Br.

[0036] In some implementations, R 11 Optional The R 0 Each was independently selected from C 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl groups, CN, OH, halogen, NH2, -NCH2CH3, -N(CH3)2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2, preferably C. 1-4 Alkyl, C 1-4 Alkoxy, C 1-4 Halogenated alkyl, OH, halogen, NH2 or -N(CH3)2, more preferably methyl, ethyl, isopropyl, methoxy, ethoxy, -CF3, OH, F, Cl, Br, NH2 or -N(CH3)2, most preferably methyl, ethyl, methoxy, ethoxy, -CF3, OH, F, Cl, Br, NH2 or -N(CH3)2, for example methoxy, -CF3 or -N(CH3)2.

[0037] In some implementations, Xaa in Equation 1a 1 In the middle, Z can be selected from C. 1-3 Alkylene, which may optionally be substituted with one or more methyl, ethyl or F.

[0038] In some implementations, Z can be selected from -CH2-, -CH2CH2-, or -CH(CH3)-.

[0039] In a preferred embodiment, R 12 It can be selected from H or methyl.

[0040] In some implementations, in Xaa 2 Chinese R 21It is selected from substituted or unsubstituted 9-10 fused cyclic heteroaryl groups, preferably 9-membered fused cyclic heteroaryl groups, containing 1, 2, 3 or 4 heteroatoms selected from S, O or N as ring atoms, preferably containing 1 or 2 heteroatoms selected from S or N as ring atoms.

[0041] In some implementations, in Xaa 2 In the middle, R 21 Selected from indolyl, benzothiophene, and pyrrolopyridyl. In some embodiments, in Xaa 2 In the middle, R 21 Selected from Preferably, in Xaa 2 In the middle, R 21 Selected from

[0042] In some implementations, in Xaa 3 In the middle, R 31 Selected from substituted or unsubstituted C 3-4 Aminoalkyl or 5-6 membered heterocyclic alkyl, preferably the 5-6 membered heteroalkyl contains 1, 2 or 3 heteroatoms selected from O, N or S, preferably 1 or 2.

[0043] In some implementations, in Xaa 3 In the middle, R 31 Selected from substituted or unsubstituted C 3-4 Aminoalkyl or 6-membered heterocyclic alkyl.

[0044] In some implementations, in Xaa 3 In the middle, R 31 Selected from substituted or unsubstituted aminopropyl (e.g., -CH2CH2CH2NH2), piperidinyl, or piperazine.

[0045] In some implementations, in Xaa 3 In the middle, R 31 Selected from -CH2CH2CH2NH2,

[0046] In one aspect, this application provides a targeting peptide or a pharmaceutically acceptable salt thereof, as shown in formula (I):

[0047] HD-Phe-ring [Cys-Xaa] 1 -Xaa 2 -Xaa 3 -Thr-Cys]-Xaa 4 Formula (I)

[0048] Among them, Xaa 1 It consists of α or β amino acid residues of type L or D, and has the structure of formula 1a:

[0049] Where n is selected from 0 or 1;

[0050] When n is 1, Xaa 1 It is a pyridine alanine residue (i.e., Pal), preferably 4-Pal.

[0051] When n is 0, R 11 Selected from one or more R-substituted phenyl, 4-hydroxyphenyl, or 5- to 10-membered heteroaryl groups, wherein the 4-hydroxyphenyl or 5- to 10-membered heteroaryl group is optionally substituted by one or more R... 0 Instead, the R 0 Each was independently selected from C 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 One or more of the following: haloalkyl, CN, OH, halogen, NH2, -NCH2CH3, -N(CH3)2, -B(OH)2, -PO(OH)2, -SO(OH)2, or -O-PO(OH)2, wherein each R is independently selected from C. 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 One or more of the following: alkyl halogroup, halogen, NH2, -NCH2CH3, -N(CH3)2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2;

[0052] R 12 Selected from H or C 1-3 Alkyl, preferably H, methyl, ethyl, or isopropyl;

[0053] Z is selected from one or more Cs. 1-3 alkyl or halogen-substituted C 1-4 Alkylene;

[0054] Among them, Xaa 2 It consists of L or D type α-amino acid residues and has the structure of Formula 1b:

[0055] Among them, R 21 Selected from cyclohexanediol groups, wherein the cyclohexanediol group may optionally be C 1-6 Alkyl, C 1-6 One or more substitutions of alkoxy, CN, OH, halogen, or amino;

[0056] Among them, Xaa 3 It consists of L or D type α amino acid residues and has the structure of the following formula 1c:

[0057] Among them, R 31Selected from substituted or unsubstituted C 1-6 Aminoalkyl or 5-6 membered heterocyclic alkyl, wherein C 1-6 The aminoalkyl or 5-6 membered heterocyclic alkyl group is optionally C 1-4 One or more substitutions of alkyl, OH, amino, or halogen;

[0058] Among them, Xaa 4 Selected from Thr-OH or Thr-ol;

[0059] Among them, Xaa in the peptide compound 1 Xaa 2 and Xaa 3 They are not both natural amino acid residues;

[0060] The condition is that when Xaa 2 Xaa 3 and Xaa 4 All are natural amino acid residues, and R 11 When selected from 4-hydroxyphenyl, the 4-hydroxyphenyl is reacted with one or more R 0 Replace and R 0 Not I; or, when Xaa 4 It is Thr-ol, and Xaa 2 For Trp, Xaa 3 When it is Lys, R 11 The phenyl group is selected from one or more R-substituted phenyl groups, and R is selected from one or more of NH2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2.

[0061] In some implementations, Xaa 1 It is an L-type α or β amino acid residue, preferably an L-type α amino acid residue.

[0062] Among them, regarding the arbitrary choice of R 0 Substituted 4-hydroxyphenyl and 5- to 10-membered heteroaryl groups are defined as above.

[0063] In some implementations, Xaa in Equation 1a 1 In the middle, R 11 The phenyl group may be selected from one or more R-substituted phenyl groups, and each R is independently selected from C. 1-6 Alkyl, C 1-6 Alkoxy, C 1-6The alkyl halogroup, NH2, -N(CH3)2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2, preferably selected from NH2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2, and even more preferably selected from NH2, -B(OH)2, -PO(OH)2 or -O-PO(OH)2.

[0064] In some implementations, Xaa in Equation 1a 1 Chinese R 11 Optional Wherein R is selected from C 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Haloalkyl, CN, halogen, NH2, -NCH2CH3, -N(CH3)2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2, preferably C 1-4 Alkyl, C 1-4 Alkoxy, C 1-4 Halogenated alkyl, OH, halogen, NH2, -N(CH3)2, -B(OH)2 or -O-PO(OH)2, more preferably NH2, -B(OH)2, -PO(OH)2, -SO(OH)2 or -O-PO(OH)2, for example NH2, -B(OH)2, -PO(OH)2 or -O-PO(OH)2.

[0065] In some implementations, Xaa in Equation 1a 1 In this context, each of the R values ​​is independently selected from -B(OH)2, -PO(OH)2, or -O-PO(OH)2.

[0066] Z, R 12 Xaa 2 Xaa 3 and Xaa 4 As defined above.

[0067] In some embodiments, Xaa in formula (I) of this application 1 In the middle, R 11 Optional

[0068] In some embodiments, Xaa in formula (I) of this application 1 In the middle, R 11 Optional

[0069] In some embodiments, Xaa in formula (I) of this application1 In the middle, R 11 Optional

[0070] In some implementations, Xaa in Equation 1a 1 In the middle, Z can be selected from C. 1-3 Alkylene, which may optionally be substituted with one or more methyl, ethyl or F.

[0071] In some implementations, Z can be selected from -CH2-, -CH2CH2-, or -CH(CH3)-.

[0072] In a preferred embodiment, R 12 It can be selected from H or methyl.

[0073] In some implementations, in Xaa 2 In the middle, R 21 It is selected from substituted or unsubstituted 9-10 fused cyclic heteroaryl groups, preferably 9-membered fused cyclic heteroaryl groups, containing 1, 2, 3 or 4 heteroatoms selected from S, O or N as ring atoms, preferably containing 1 or 2 heteroatoms selected from S or N as ring atoms.

[0074] In some implementations, in Xaa 2 In the middle, R 21 Selected from indolyl, benzothiophene, and pyrrolopyridyl. In some embodiments, in Xaa 2 Chinese R 21 Selected from Preferably, in Xaa 2 Chinese R 21 Selected from

[0075] In some implementations, in Xaa 3 In the middle, R 31 Selected from substituted or unsubstituted C 3-4 Aminoalkyl or 5-6 membered heterocyclic alkyl, preferably the 5-6 membered heteroalkyl contains 1, 2 or 3 (preferably 1 or 2) heteroatoms selected from O, N or S.

[0076] In some implementations, in Xaa 3 In the middle, R 31 Selected from substituted or unsubstituted C 3-4 Aminoalkyl or 6-membered heterocyclic alkyl.

[0077] In some implementations, in Xaa 3 In the middle, R 31 Selected from substituted or unsubstituted aminopropyl (e.g., -CH2CH2CH2NH2), piperidinyl, or piperazine.

[0078] In some implementations, in Xaa 3 In the middle, R 31 Selected from -CH2CH2CH2NH2,

[0079] In some preferred embodiments, this application provides somatostatin receptor targeting peptides or pharmaceutically acceptable salts thereof as shown in formulas (I-1), (I-2), (I-3), (I-4), and (I-5):

[0080] Among them, Z and R 11 R 21 and R 31 The prerequisites are as defined above.

[0081] In some preferred embodiments, this application provides somatostatin receptor targeting peptides or pharmaceutically acceptable salts thereof as shown in formulas (I-11), (I-12), (I-13), (I-14), (I-15), (I-16), (I-17), (I-18), (I-19), or (I-20):

[0082] Among them, R 0 , R, R 12 The definitions and prerequisites are as above; each M is independently CH or N, with at least one being N;

[0083] Where p is selected from 0 or 1, q is selected from 1 or 2, and X is selected from N or CH.

[0084] In another aspect, this application provides a somatostatin receptor-targeting peptide or a pharmaceutically acceptable salt thereof, said somatostatin receptor-targeting peptide having the structure shown in formula (II):

[0085] H-Xaa 5 - Ring [D-Cys-Xaa] 6 -Xaa 7 -Lys-Thr-Cys]-Xaa 8 -NH2 formula (II),

[0086] Among them, Xaa 5 For Phe(R) 1 ), the R 1 Selected from chlorine or nitro groups;

[0087] Among them, Xaa 6It is selected from L-type or D-type (preferably L-type) α-amino acid residues and has the structure of the following formula (II-a):

[0088] in,

[0089] Y is selected from N or CH.

[0090] R 61 Independently selected from OH and C 1-6 Alkyl, C 1-6 Alkyl group, CN, halogen, substituted or unsubstituted amino group, or -B(OH)2, -O-PO(OH)2, wherein the amino group is optionally C 1-6 Alkyl, C 1-6 One or more substitutions in alkoxy and (hexahydro-2,6-dioxo-4-pyrimidinyl)carbonyl, where m can be 0, 1 or 2;

[0091] Among them, Xaa 7 Selected from type D, R 71 The substituted phenylalanine residue, said R 71 Selected from -NHCONH2 or -B(OH)2; preferably substituted at the 4-position on the benzene ring;

[0092] Among them, Xaa 8 Selected from type D, R 81 The substituted phenylalanine residue, said R 81 Selected from OH, -B(OH)2, -O-PO(OH)2; preferably substituted at the 4-position of the benzene ring;

[0093] The condition is that when Y is selected from N and m is 0, R 1 Not chlorine; (preferably, when Y is selected from N and R) 61 When R is not -B(OH)2 or -O-PO(OH)2, 1 (Not chlorine); or R 61 R 71 R 81 At least one of them is selected from -B(OH)2 or -O-PO(OH)2.

[0094] In one embodiment, formula (II-a) may be the following formula (II-1):

[0095] Where Y can be selected from N or CH;

[0096] R 61 It can be independently selected from OH and C. 1-6 Alkyl, C 1-6Alkyl group, CN, halogen, substituted or unsubstituted amino group, or -B(OH)2, -O-PO(OH)2, wherein the amino group is optionally C 1-6 Alkyl, C 1-6 One or more of the following substitutions: alkoxy and 4-[(4S)-hexahydro-2,6-dioxo-4-pyrimidinyl]carbonyl-.

[0097] In one implementation, Xaa 6 It consists of L-type α-amino acid residues.

[0098] In one implementation, R 61 Selected from OH, -B(OH)2 or In a preferred embodiment, R 61 Both are located at the para position of the aromatic ring. In a preferred embodiment, R 61 All are at the para position of the phenyl group.

[0099] In one implementation, Xaa 6 Selected from Tyr, Aph(Hor), pyridinealanine residues or dihydroxyboryl-phenylalanine residues.

[0100] In one implementation, Xaa 6 Selected from Tyr, Aph(Hor), 2-pyridinealanine residue, 4-pyridinealanine residue, or 4-dihydroxyboryl-phenylalanine residue.

[0101] In one implementation, Xaa 7 It is selected from 4-dihydroxyboryl-phenylalanine residues of type D and Aph(Cbm).

[0102] In one implementation, Xaa 8 Selected from D-Tyr, and D-type 4-dihydroxyboryl-phenylalanine residues or D-type 4-phosphophenylalanine residues.

[0103] In one aspect, this application provides a somatostatin receptor targeting peptide or a pharmaceutically acceptable salt thereof, said targeting peptide having any of the structures selected from the following:

[0104] In some embodiments, the above-mentioned somatostatin receptor-targeting peptide or a pharmaceutically acceptable salt thereof can be used as an SSTR2 agonist or an SSTR2 antagonist.

[0105] In another aspect, this application provides a somatostatin receptor targeting peptide or a pharmaceutically acceptable salt thereof, said targeting peptide having any of the structures selected from the following:

[0106] SSTR2 binding molecules

[0107] On the other hand, this application also provides an SSTR2 binding molecule comprising the somatostatin receptor-targeting peptide described above or a pharmaceutically acceptable salt thereof.

[0108] For example, the N-terminal amino acid of the target peptide of this application may be added in various ways, such as by linking the desired portion to the target peptide of this application or by providing a labeled chelating agent or conjugating agent, thereby providing the SSTR2 binding molecule of this application. For example, the SSTR2 binding molecule may further comprise a chelating agent, chelating agent, conjugating agent, or labeling agent.The chelating agent may be selected from ethylenediaminetetraacetic acid (EDTA), 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), N,N"-bis[2-hydroxybenzyl]ethylenediamine-N,N"-diacetic acid (HBED), N,N"-bis[2-hydroxy-5-(carboxyethyl)-benzyl]ethylenediamine-N,N"-diacetic acid (HBED-CC), N-2-hydroxy-5-(tetrafluorophenyl ethyl)-benzyl-N"-2'-hydroxy-5'-(carboxyethyl)-benzylethylenediamine-N,N"-diacetic acid (HBED-CC-TFP), N,N"-bis[3-carboxypyridinemethyl]ethylenediamine (DEDPA), 1,4,7-triazacyclononane-1,4,7,10-tetraacetic acid (DOTA), N,N"-bis[2-hydroxybenzyl]ethylenediamine-N,N"-diacetic acid (DOTA ...]pyridinemethyl]ethylenediamine (DEDPA), N,N"-triazacyclononane-1,4,7-tetraacetic acid (DOTA), N,N"-bis[2-hydroxybenzyl]ethylenediamine-N,N"-diacetic acid (DOTA), N,N"-bis[3-carboxy]pyridinemethyl]ethylenediamine (DEDPA), N,N"-triazacyclononane-1,4,7-tetraacetic acid (DOTA), N,N"-bis 7-Triacetic acid (NOTA), 2-(4,7-bis(carboxymethyl)-1,4,7-triazolyl-1-yl)glutaric acid (NODAGA), 2-(4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane-1-yl)glutaric acid (DOTAGA), 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (TETA), 1,4,8,11-tetraazacyclotetradecane-1,8-diacetic acid (TE2A), 4,11-bis(carboxymethyl)-1,4,8,11-tetraazabicyclo[6,6,2]hexadecane (CB-TE2A), 1,4,7-triazacyclononane-1,4,7-trimethylphosphonic acid (TRAP) 1,4,7-Triazacyclononane-1,4,7-tris[methyl(2-hydroxymethyl)phosphonic acid] (TRAP-OH), 1,4,7-triazacyclononane-1,4,7-tris[methyl(2-carboxyethyl)phosphonic acid] (TRAP-Pr), 1,4,7-triazacyclononane-1-[methyl(2-carboxyethyl)phosphonic acid]-4,7-bis[methyl(2-hydroxymethyl)phosphonic acid] (NOPO), 3,6,9,15-tetraazabicyclo[9,3,1]pentadecane-1(15),11,13-triene-3,6,9-triacetic acid (PCTA), diethyltriaminepentaacetic acid (DTPA), 1,4,7,10,13-pentaazacyclopentadecane-1,4,7,10,1 3-Pentaacetic acid (PAPA), 1,4,7,10,13,16-hexaazacyclooctadecane-1,4,7,10,13,16-hexaacetic acid (HEHA), 10-phosphonomethyl-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3AP), 10-(2-carboxyethyl)phosphonomethyl-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3APPrA), 6-bis(carboxymethyl)amino-6-methyl-1,4-diazacycloheptane-1,4-diacetic acid (AAZTA), 2-hydrazinenicotinamide (HYNIC), N4-chelating agents, deferoxamine and NxSy-chelating agents, Macropa, Crown, α. 10-(4-aminobutyl)-DOTA, α 4 , 10 -Dicarboxyethyl-DOTA, α 10 -(cyanothiophenyl)methyl)-DOTA, α 4 , 10 -(4-aminobutyl)-DOTA, or their derivatives (e.g., their carboxylic acid ester derivatives). Based on the above chelating agents, they can optionally be complexed with radioactive isotopes, tyrosine (Tyr) for halogenation, fluorescent dyes, or biotin. In addition, Cpa can also be used as a precursor for tritiumization.

[0109] In addition, such chelating agents, complexing agents, conjugators, or labels can be directly or via a linker to the α-amino group of the N-terminal residue of a somatostatin receptor-targeting peptide or its pharmaceutically acceptable salt, or directly linked to the N / C-terminal or intermediate amino acid residue.

[0110] Alternatively, if desired, the chelating agent, complexing agent, conjugating agent, or label can be covalently linked to the N / C terminal or intermediate amino acid residue via a suitable linker (linker or spacer). Alternatively, the polypeptide of this application can be directly covalently linked to the chelating agent, complexing agent, conjugating agent, or label at its N / C terminal or intermediate amino acid residue. In a preferred embodiment, the SSTR2 binding molecule comprises a radionuclide. For example, the radionuclide can be labeled, complexed, conjugated, or chelated to a substance directly or via a linker to the amino group of the N-terminal residue of the somatostatin receptor targeting peptide.

[0111] Adding the N-terminus of the somatostatin receptor-targeting peptide does not adversely affect its specific binding to SSTR2. Therefore, it is understood that these somatostatin receptor-targeting peptides can be complexed with radionuclides (e.g., chelates formed by chelation via chelating agents, complexing agents, conjugating agents, or direct complexation) to deliver the substance to tumors or other tissues where apoptosis is desired. For example, radiolabeled somatostatin peptide analogs can be used, for instance, with... 186 Re、 188 Re、 111 In、 113 mIn, 71 As、 90 Y、 64 Cu、 67 Cu、 99 mTc, 169 Er、 121 Sn、 127 Te、 142 Pr, 143 Pr、 66 Ga、 67 Ga、 68 Ga、 72 Ga、127 Te、 195 Pt, 18 F, 211 At、 198 Au、 199 Au、 161 Tb, 109 Pd, 165 Dy、 149 Pm, 151 Pm, 153 Sm、 157 Gd, 159 Gd, 166 Ho、 172 Tm、 169 Yb、 175 Yb、 177 Lu、 225 Ac、 203 Pb, 212 Pb, 105 Rh、 114 Ag、 124 I or 131 I, or 138 La, or 223 Ra, or 89 Sr is used to mark.

[0112] These somatostatin receptor-targeting peptides can also be complexed with non-radioactive metal nuclides (also known as cold metal nuclides) (e.g., chelates formed through chelation via chelating agents, complexing agents, or conjugating agents, or direct complexation) to study various properties, labeling behaviors, and other material characteristics of the substance, which are equivalent to those of substances complexed with radioactive metal nuclides. In some embodiments of the present invention, the non-radioactive metal nuclides are selected from... 175 Lu、 139 La、 113 In、 115 In、 89 Y、 144 Sm、 147 Sm、 148 Sm、 149 Sm、 150 Sm、 152 Sm、 154 Sm、 185 Re、 69 Ga、 71 Ga、 63 Cu、 65 Cu.

[0113] For example, suitable chelating agents can be used to complex somatostatin peptide analogs with the aforementioned highly radioactive metals. These chelating agents may be derived from, for example, DOTA or NODAGA or DOTAGA or NOTA.

[0114] In some embodiments, the SSTR2 binding molecule comprises a peptide compound selected from formula (I), formula (II), or any one of formulas I-1 to I-20.

[0115] In a preferred embodiment, the SSTR2 binding molecule comprises a somatostatin peptide analog selected from any one of formula (I) or a pharmaceutically acceptable salt thereof. In a preferred embodiment, the SSTR2 binding molecule comprises a somatostatin peptide analog selected from any one of formula (II) or a pharmaceutically acceptable salt thereof.

[0116] In some embodiments, the SSTR2 binding molecule comprises a somatostatin peptide analog or a pharmaceutically acceptable salt thereof selected from any one of Formula (I), Formula (II), (I-1), Formula (I-2), Formula (I-3), Formula (I-4), Formula (I-5), Formula (I-11), Formula (I-12), Formula (I-13), Formula (I-14), Formula (I-15), Formula (I-16), Formula (I-17), Formula (I-18), Formula (I-19), and Formula (I-20), and may further comprise a radionuclide.

[0117] In a preferred embodiment, the SSTR2 binding molecule or targeting peptide conjugate may be selected from one or more of the following: DOTA-targeting peptides; further, it may also contain a radionuclide (e.g., 177 Lu or 67 Ga or 68 Ga or 225 Ac). In a preferred embodiment, the targeting peptide is connected to DOTA via a connector.

[0118] In a preferred embodiment, the SSTR2 binding molecule may be selected from one or more of the following:

[0119] Furthermore, it may also contain radioactive nuclides (e.g. 177 Lu、 225 Ac or 68 Ga).

[0120] Composition

[0121] According to another embodiment of this application, a composition is provided comprising the targeted peptide described herein or a pharmaceutically acceptable salt thereof, or the SSTR2 binding molecule described herein, and a physiologically acceptable and / or pharmaceutically acceptable carrier. In some embodiments, the composition may be a pharmaceutical composition.

[0122] This application provides pharmaceutical compositions comprising the targeted peptide described herein or a pharmaceutically acceptable salt thereof, or the SSTR2 binding molecule described herein, and a pharmaceutically acceptable carrier.

[0123] In some embodiments of this application, the composition contains at least one targeting peptide as described in any embodiment of this application, or a pharmaceutically acceptable salt or SSTR2-binding molecule thereof. For example, the composition contains at least two targeting peptides as described in any embodiment of this application, or pharmaceutically acceptable salts or SSTR2-binding molecules thereof (including but not limited to two, three, four, five, six, seven, eight, nine, ten or more) as active ingredients.

[0124] In some embodiments of this application, the composition may be a liquid formulation, such as an injection. In some embodiments of this application, the composition may also be a lyophilized powder for injection, which is mixed with liquid excipients to form a liquid formulation for administration. In some embodiments of this application, the liquid formulation may be for subcutaneous, intramuscular, or intravenous administration. In some embodiments of this application, the liquid formulation may be for administration via spray to the lungs, or via spray to other organs or tissues (such as the lungs, gastrointestinal tract, and kidneys). In some embodiments of this application, the pharmaceutical composition is for intravenous administration.

[0125] In some embodiments of this application, the pharmaceutical composition may be configured to be suitable for delivery to treat diseases in all known organs expressing SSTR2, including the lungs, gastrointestinal tract, and kidneys.

[0126] In some embodiments, this application relates to pharmaceutical compositions comprising an SSTR2 antagonist. In some embodiments, this application relates to pharmaceutical compositions comprising an SSTR2 agonist.

[0127] In some embodiments, this application relates to pharmaceutical compositions for treating diseases, conditions, or disorders mediated and / or associated with SSTR2; pharmaceutical compositions for treating cancer; or pharmaceutical compositions for radiographic imaging of cancer or tumors.

[0128] In addition, this application provides a pharmaceutical composition comprising SSTR2 of this application or a pharmaceutically acceptable salt thereof, a second therapeutic agent, and a pharmaceutically acceptable carrier.

[0129] Uses and application

[0130] The targeting peptides and their pharmaceutically acceptable salts according to this application are also used to selectively block certain SSTR2-mediated pharmacological effects, such as as SSTR2 modulators (including agonists and antagonists). Many of these effects are known or understood by those skilled in the art. For example, non-radiolabeled peptides can be used to treat diseases in all organs known to express SSTR2, including the lungs, gastrointestinal tract, and kidneys.

[0131] Furthermore, SSTR2 is overexpressed in various solid tumors, including neuroendocrine tumors, thyroid cancer, breast cancer, gastric cancer, liver cancer, and lung cancer. Given its widespread expression and important role in tumors, SSTR2 has become a crucial target for tumor imaging and therapy. In this context, the combined administration of the SSTR2 modulator (i.e., the targeted peptide or a pharmaceutically acceptable salt thereof) according to this application with a radionuclide can significantly improve in vivo targeting of such tumors.

[0132] According to some embodiments of this application, the targeting peptides described herein, or pharmaceutically acceptable salts thereof, can be used to determine tumor location and cellular expression of the receptor SSTR2, as well as to modulate certain pharmacological functions. When such targeting peptides comprise suitable chelated radionuclides, these targeting peptides can be used as radiopharmaceuticals suitable for radionuclide therapy to treat tumors.

[0133] Furthermore, the targeting peptides of this application can also be used in scintillation scanning to determine the distribution of SSTR2-expressing cells and tissues throughout the body. The use of external imaging via radiographic scanning or magnetic resonance allows for semi-quantitative detection in vivo. Therefore, such radiolabeled peptide compounds can be used, for example, in scintillation scanning to locate tumors expressing the receptor in vitro or in vivo, such as using single-photon emission computed tomography (SPECT) or positron emission tomography (PET).

[0134] Other types of markings besides radioactive markings are known in the art, such as fluorescent markings, and may be used optionally.

[0135] Therefore, in some embodiments, this application provides the use of the target peptide described herein or a pharmaceutically acceptable salt thereof in the preparation of SSTR2 modulators, which include agonists and antagonists.

[0136] In some embodiments, this application provides an SSTR2 modulator comprising the targeting peptide described in this application or a pharmaceutically acceptable salt thereof, or the SSTR2 binding molecule described in this application.

[0137] In some embodiments, this application provides methods for treating or preventing SSTR2-mediated diseases, conditions, or disorders, comprising administering to a subject a preventatively effective or therapeutically effective amount of the target peptide of this application and its pharmaceutically acceptable salt, or the SSTR2-binding molecule of this application, or a pharmaceutical composition.

[0138] In some embodiments, this application provides methods for treating cancer / tumor or imaging cancer / tumor. In some embodiments, this application provides methods for diagnosing cancer using radiographic imaging. For example, such radiolabeled SSTR2-binding molecules of this application can be effectively used in scintillation scanning or for suppressing or controlling the amount of tumor / tumor.

[0139] For example, such SSTR2-binding molecules containing radionuclides could be used for the therapeutic treatment of malignant tumors in healthy human tissues that do not contain significant amounts of SSTR2. Therefore, this application relates to a method for treating cancer / tumor, the method comprising administering a therapeutically effective amount of the SSTR2-binding molecules containing radionuclides described in this application to a subject in need.

[0140] In addition, this application also relates to methods for detecting, for example, malignant tumors in tissues of healthy subjects that do not contain large amounts of SSTR2.

[0141] In one embodiment, this application relates to the use of an SSTR2 binding molecule in the preparation of a medicament for treating cancer / tumor, wherein the SSTR2 binding molecule comprises the peptide compound described in this application or a pharmaceutically acceptable salt thereof, and a radionuclide.

[0142] In one embodiment, this application also relates to a method of radiographic cancer imaging, comprising (a) administering an SSTR2-binding molecule containing a radionuclide as described in this application; and (b) detecting the radionuclide.

[0143] Furthermore, the peptide compounds or SSTR2-binding molecules described in this application can be used in drug screening assays to screen for novel, potent peptides and non-peptide substances that bind to SSTR2 with high affinity and are highly effective modulators. For example, competitive binding affinity between labeled peptide compounds of this type and candidates to SSTR2 can be determined using such assays.

[0144] Therapeutic amounts of the peptide compounds or SSTR2-binding molecules of this application should be administered under the guidance of a physician, and pharmaceutical compositions typically contain peptides that bind to conventional pharmaceutically or veterinarily acceptable carriers. A therapeutically effective amount is considered to be a predetermined amount calculated to achieve the desired effect. The required dose varies depending on the specific treatment and the desired duration of treatment.

[0145] The SSTR2 modulators of this application, or their non-toxic salts or SSTR2-binding molecules, which are combined with pharmaceutically acceptable carriers to form pharmaceutical compositions, may be administered intravenously, subcutaneously, intramuscularly, percutaneously (e.g., intranasally, intracerebrospinal), or orally to animals, including humans and other mammals. Such pharmaceutical compositions designed for the detection of malignant human tumors (including metastases) in tissues may, in addition to pharmaceutically acceptable carriers, include optional pharmaceutically acceptable adjuvants, peptide compounds sufficient for external imaging to detect via gamma detection probes, or labeled peptide compounds as active substances for inhibiting or controlling tumors.

[0146] Reagent test kit

[0147] According to embodiments of this application, a kit is provided comprising the target peptide described in this application or a pharmaceutically acceptable salt thereof, or an SSTR2 binding molecule, or a combination thereof, and instructions for use.

[0148] In one embodiment, a kit for diagnosing radiographic cancer is provided, comprising the peptide compound described herein or a pharmaceutically acceptable salt thereof, or an SSTR2 binding molecule, or a combination thereof, and instructions for use.

[0149] In one embodiment, a kit for treating cancer is provided, comprising the peptide compound described in this application or a pharmaceutically acceptable salt thereof, or an SSTR2 binding molecule, or a combination thereof, and instructions for use.

[0150] When used for imaging or therapeutic purposes, the poor shelf life of radiolabeled compounds and / or the short half-life of radionuclides may require users to perform radionuclide labeling reactions in clinical hospitals or laboratories. In such cases, a “kit” can provide users with a variety of reaction components. The procedures necessary to perform the desired reaction should be as simple as possible so that users can prepare radioactively labeled compositions from the kit using conventional single-use tools. Thus, a kit for preparing radiopharmaceutical compositions, detecting and locating malignant tumors and their metastases in tissues may contain (i) an SSTR2-binding molecule comprising the targeting peptide described herein or a pharmaceutically acceptable salt thereof and a chelating agent, a pharmaceutically acceptable carrier and / or excipient, and optional adjuvants, (ii) a solution of a salt or chelate of a radiometal isotope, and (iii) instructions for use containing a formulation for reacting the components present in the kit.

[0151] When the radionuclide is present in the kit itself, the complexation reaction with the peptide can be easily achieved by combining the components in a neutral medium and allowing them to react.

[0152] The peptide components of the kit may be provided as solutions, such as saline solution or in some buffer solution, but are preferably present in a dry state, such as lyophilized state. When used as components for injection, they should be sterile. When the components are in a dry state, the user should use sterile saline solution as a solvent. If necessary, the components may be stabilized in a conventional manner with suitable stabilizers, such as ascorbic acid, gentian acid, or salts of these acids.

[0153] Preparation method

[0154] The targeted peptides or pharmaceutically acceptable salts thereof described in this application can be synthesized by classical solution synthesis, preferably by solid-phase synthesis on resins as known in the art. Peptides having a free carboxyl C-terminus can be synthesized as taught in U.S. Patent No. 7,019,109, the contents of which are incorporated herein by reference in their entirety. Peptides having an amidated C-terminus can be synthesized as taught in U.S. Patent No. 5,874,227, the contents of which are incorporated herein by reference in their entirety.

[0155] Solid-phase synthesis is carried out stepwise by adding amino acids to the chain starting at the C-terminus. Side-chain protecting groups, known in the art, are added as part of any amino acid having a specific reactive side chain, wherein such amino acids are coupled to the chain built on the resin. This type of synthesis provides a fully protected intermediate peptide resin. The protecting group is generally separated before disulfide bonds are formed between the Cys side chains, after which the peptide is cleaved from the resin support.

[0156] For cases where chelating agents or the like are added to the peptide compound (especially the N-terminus), solid-phase synthesis methods can also be used for ease of operation. For example, after forming disulfide bonds between Cys side chains and removing protecting groups, a peptide-resin is used to link the peptide compound with the chelating agent, and then the peptide is cleaved and separated from the resin support.

[0157] This application provides an improved somatostatin analogue that specifically targets and regulates SSTR2 and provides significantly improved binding affinity, pharmacokinetics, and biodistribution, thereby improving the therapeutic efficacy of PRRT by improving these parameters.

[0158] This application also provides an SSTR2-binding molecule (e.g., a peptide-nucleoside conjugate) containing this somatostatin analog. In the case of a reflective nuclide, this molecule, due to the high energy released by the nuclide, can kill cancer cells while also killing normal cells. Therefore, the targeting ligand portion needs to have a tumor-specific selectivity, meaning that after entering the body, it can quickly reach the tumor site, while the remainder is cleared and excreted by the kidneys, with almost no uptake by other normal tissues and organs.

[0159] SSTR2 is expressed in many normal tissues, including the pancreas, adrenal glands, and stomach. Therefore, the existing radiolabeled somatostatin analogs do not exhibit clean biodistribution in tumor model mice. Besides the tumor, other normal organs and tissues (especially the pancreas, adrenal glands, and stomach) also show some uptake. At high doses, this can easily lead to toxicity to normal organs and tissues, thus limiting the exploration of effective doses. However, the somatostatin analog of this application significantly improves these shortcomings. Compared to Lutathera's TATE (Tyr3-octreotate), the somatostatin analog of this application has comparable or even higher in vitro activity. Furthermore, while maintaining comparable in vitro activity, the radiolabeled somatostatin exhibits better tumor specificity after being linked to a chelating agent or linked via a linker or spacer. While achieving high uptake and enrichment in tumors, the uptake in other normal non-target organs is very low, resulting in good tumor suppression and lower toxicity or other side effects.

[0160] definition

[0161] Unless otherwise stated, the terms used in the specification and claims below shall have the following meanings. A particular term, unless specifically defined, shall not be considered ambiguous or unclear, but shall be understood in accordance with its conventional meaning in the art. As used herein, “natural amino acid” or “natural amino acid residue” refers to amino acids synthesized naturally in living organisms through metabolic pathways; these amino acids are the basic building blocks of proteins. In living organisms, 20 standard amino acids are widely used in protein synthesis; these amino acids are called coding amino acids or natural amino acids. They are encoded in the genetic code and assembled into proteins through ribosome translation. The following are the names, three-letter abbreviations, and single-letter abbreviations of the 20 natural amino acids, all of which are L-type amino acids: Alanine (Ala–A); Arginine (Arg–R); Aspartic Acid (Asp–D); Asparagine (Asn–N); Cysteine ​​(Cys–C); Glutamic Acid (…). Acid-Glu–E; Glutamine-Gln–Q; Glycine-Gly–G; Histidine-His–H; Isoleucine-Ile–I; Leucine-Leu–L; Lysine-Lys–K; Methionine-Met–M; Phenylalanine-Phe–F; Proline-Pro–P; Serine-Ser–S; Threonine-Thr–T; Tyrosine-Tyr–Y; Valine-V; Tryptophan-Trp–W.

[0162] The standard three-letter abbreviation represents an α-amino acid residue, where the amino acid residue has an isomer form, unless otherwise explicitly stated, it represents an L-form amino acid residue (e.g., Tyr = L-tyrosine residue). "L" or "D" refers to the L-isomer and D-isomer of a particular amino acid.

[0163] In this application, amino acid -OH indicates that the amino acid residue is carbon-terminated and the carboxyl group at the carbon terminus remains unchanged; amino acid -ol indicates that the amino acid residue is carbon-terminated and the carboxyl group at the carbon terminus is replaced with a hydroxymethyl group; amino acid -NH2 indicates that the amino acid residue is carbon-terminated and the carboxyl group at the carbon terminus is replaced with -CONH2; for example, Thr-OH indicates... Thr-ol indicates Tyr-NH2 indicates

[0164] In this application, amino acid (R) 1 ) indicates that amino acid residues are affected by R 1 Replacement (preferably by an R) 1 (Substitution), or the side chain group of an amino acid or amino acid residue is replaced by R. 1 Protection (preferably full protection). For example, when the side chain of an amino acid residue has a basic group (e.g., NH2, NH, etc.), a hydroxyl group, a carboxyl group, a thiol group, etc., the basic group (e.g., NH2, NH, etc.), hydroxyl group, carboxyl group, thiol group, etc. are protected by the protection group R. 1 Protection; when the amino acid or the side chain of the amino acid residue does not have the aforementioned groups requiring protection, the amino acid residue is protected by R. 1 Substitution (preferably monosubstitution, preferably ring substitution when the amino acid residue has an aromatic ring; more preferably 4- or para-substitution). For example, Phe(R 1 ) indicates that the phenylalanine residue is separated by an R 1 Substitution (preferably by an R on the benzene ring) 1 In some implementations, Phe(R) 1 ) can be, for example Preferred For example, "Lys(R) 1 "-OH" indicates that the NH2 in the side chain of the lysine residue is reacted with R. 1 Protection, that is Specifically, for example, Lys(Boc) represents an L-type lysine residue in which the NH2 of the side chain is protected by Boc.

[0165] In this application, Pal represents a pyridine alanine residue with the following structure: This includes amino acid residues in which a pyridinyl group is linked to alanine via a suitable site, specifically including 2-pyridinealanine residues (2-Pal). 3-Pyridinealanine (3-Pal) and 4-pyridinealanine residues (4-Pal) The structure of Aph(Hor) (i.e., 4-[(2,6-dioxo-hexahydropyrimidine-4-carbonyl)-amino]phenylalanine residue) is: The structure of the 4-dihydroxyboryl-phenylalanine residue is as follows: The structure of Aph(Cbm) (i.e., 4-aminocarbamate phenylalanine residue) is as follows: The structure of the 4-phosphophenylalanine residue is as follows:

[0166] The compounds described herein may be in free form or in the form of their salts. In some embodiments, the compounds described herein may be in the form of pharmaceutically acceptable salts known in the art (Berge et al., J. Pharm. Sci. 1977, 66, 1). Pharmaceutically acceptable salts as used herein include, for example, salts having the desired pharmacological activity of the parent compound (salts that retain the biological efficacy and / or properties of the parent compound and are not biologically and / or otherwise undesirable). Compounds described herein having one or more functional groups capable of forming salts may, for example, form pharmaceutically acceptable salts. Compounds containing one or more basic functional groups are capable of forming pharmaceutically acceptable salts with, for example, pharmaceutically acceptable organic or inorganic acids. Pharmaceutically acceptable salts may be derived from, for example, but not limited to, acetic acid, adipic acid, alginic acid, aspartic acid, ascorbic acid, benzoic acid, benzenesulfonic acid, butyric acid, cinnamic acid, citric acid, camphoric acid, camphorsulfonic acid, cyclopentanepropionic acid, diethylacetic acid, digluconic acid, dodecyl sulfonic acid, ethanesulfonic acid, formic acid, fumaric acid, glucoheponic acid, gluconic acid, glycerophosphate, glycolic acid, hemisulfonic acid, heptanoic acid, hexanoic acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, 2-hydroxyethanesulfonic acid, isonicotinic acid, lactic acid, malic acid, maleic acid, malonic acid, mandelic acid, mesylic acid, 2-naphthalenesulfonic acid, naphthalenedisulfonic acid, p-toluenesulfonic acid, nicotinic acid, nitric acid, oxalic acid, dihydroxynaphthalic acid, pectic acid, 3-phenylpropionic acid, phosphoric acid, picric acid, pimelic acid, pentanoic acid, propionic acid, pyruvic acid, salicylic acid, succinic acid, sulfuric acid, aminosulfonic acid, tartaric acid, thiocyanate, or undecanoic acid. A compound containing one or more acidic functional groups is capable of forming a pharmaceutically acceptable salt with a pharmaceutically acceptable base, such as, but not limited to, inorganic bases based on alkali metals or alkaline earth metals, or organic bases such as primary amines, secondary amines, tertiary amines, quaternary amines, substituted amines, naturally occurring substituted amines, cyclic amines, or basic ion exchange resins.Pharmaceutically acceptable salts may be derived from, for example, but not limited to, hydroxides, carbonates or bicarbonates of pharmaceutically acceptable metal cations such as ammonium, sodium, potassium, lithium, calcium, magnesium, iron, zinc, copper, manganese or aluminum, ammonia, benzathine penicillin, meglumine, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, isopropylamine, tripropylamine, tributylamine, ethanolamine, diethanolamine, 2-dimethylaminoethanol, 2-diethylaminoethanol, dicyclohexylamine, lysine, arginine, histidine, caffeine, hydrabamine, choline, betaine, ethyl... Diamines, glucosamine, glucosamine, methylglucamine, theobromine, purines, piperazine, piperidine, procaine, N-ethylpiperidine, tetramethylammonium compounds, tetraethylammonium compounds, pyridine, N,N-dimethylaniline, N-methylpiperidine, morpholine, N-methylmorpholine, N-ethylmorpholine, dibenzylamine, N,N-dibenzylphenethylamine, 1-diphenylhydroxymethylamine, N,N'-dibenzylethylenediamine, or polyamine resins. In some embodiments, the compounds described herein may contain both acidic and basic groups and may be in the form of an internal salt or zwitterion, such as, but not limited to, betaine. Salts as described herein can be prepared by conventional methods known to those skilled in the art, such as, but not limited to, by reacting the free form with an organic or inorganic acid or base, or by anion or cation exchange from other salts. Those skilled in the art will understand that salts can be prepared in situ during the separation and purification of the compound, or by reacting the separated and purified compound alone.

[0167] The terms "give" or "administer" as used in this application encompass all suitable methods of delivering a substance to a patient. Common routes include oral, sublingual, transmucosal, transdermal, rectal, vaginal, subcutaneous, intramuscular, intravenous, intraarterial, intrathecal, transcatheter, transimplantal, and transimplantal. In some embodiments, the composition is administered near or directly to the tumor, for example, by direct injection into the tumor or, when the tumor is a hematoma, by injection into the bloodstream.

[0168] As used in this application, "effective amount" or "effective dose" means the amount of a drug, compound, drug conjugate, or drug composition necessary to achieve any one or more beneficial or desired therapeutic effects. For preventative use, beneficial or desired results include eliminating or reducing risk, mitigating severity, or delaying the onset of a condition, including the condition, its complications, and the biochemical, histological, and / or behavioral symptoms of intermediate pathological phenotypes presented during the development of the condition. For therapeutic use, beneficial or desired results include clinical benefit, such as reducing the incidence of SSTR2-related diseases or conditions by modulating or targeting SSTR2, and / or improving one or more symptoms of said disease or condition, reducing the dosage of other therapeutic agents required to treat said disease or condition, enhancing the efficacy of another therapeutic agent, and / or delaying the progression of SSTR2-related diseases or conditions.

[0169] In this application, "subject" generally refers to a human or non-human animal (including mammals) requiring diagnosis, prognosis, improvement, prevention, and / or treatment of a disease, or any animal being examined, studied, or treated, and is not intended to be limited to any particular type of subject. Examples of subjects include, but are not limited to, humans, non-human primates (apes, gibbons, gorillas, chimpanzees, orangutans, macaques), livestock (dogs, cats), farm animals (horses, cattle, goats, sheep, pigs), and laboratory animals (mice, rats, rabbits, guinea pigs). Human subjects include fetuses, newborns, infants, adolescents, and adult subjects. In some embodiments of this application, subjects include animal disease models. In this application, the term "subject" is used interchangeably with "individual." Those skilled in the art will recognize that specific immune co-stimulatory molecules, signaling molecules, cell markers, cell types, infectious agents, etc., discussed in relation to one species may have corresponding analogues in different species, and such analogues and their use in the corresponding and related species are included within the scope of this application.

[0170] The term "tumor" as used in this application includes solid tumors and non-solid tumors; and different stages of tumor development, from precancerous lesions and benign tumors to carcinomas, malignant tumors and metastatic tumors.

[0171] The term "high uptake enrichment" refers to the significantly increased uptake level and / or accumulation of the compound of this application (e.g., the target peptide of this application, its pharmaceutically acceptable salt or conjugate thereof) in tumor tissue relative to normal tissue or non-target tissue, or exhibits selective enrichment of tumor tissue in some embodiments.

[0172] The term "pharmaceutical composition" refers to a mixture of one or more compounds of this application (e.g., the target peptide of this application or its pharmaceutically acceptable salt or conjugate) with a pharmaceutically acceptable carrier, excipient, or excipient. The purpose of a pharmaceutical composition is to facilitate administration of the compound of this application to a test subject. In this document, the terms "pharmaceutical composition" and "formulation" have the same meaning and are used interchangeably. Carriers, excipients, or excipients as used herein include any and all solvents, diluents or other liquid excipients, dispersants or suspending agents, surfactants, isotonic agents, thickeners or emulsifiers, preservatives, solid binders, lubricants, etc., suitable for the desired particular dosage form. Various carriers, excipients, or excipients used to formulate pharmaceutically acceptable compositions and methods for their preparation may be employed using known techniques. The use of any conventional carrier media, except those incompatible with the compounds of this application (e.g., producing any adverse biological effects or otherwise interacting harmfully with any other component of the pharmaceutically acceptable composition), is covered within the scope of this application. In some specific embodiments, the carriers, excipients or excipients used herein are carriers, excipients or excipients conventionally used in the field of drug delivery.

[0173] Pharmaceutical compositions typically include one or more carriers, excipients, or diluents acceptable to the formulation administration method, whether by injection, inhalation, topical application, irrigation, oral administration, sublingual administration, transmucosal administration, transdermal administration, rectal administration, vaginal administration, subcutaneous administration, intramuscular administration, intravenous administration, intraarterial administration, intrathecal administration, via catheter, via implant, or other methods suitable for the selected treatment. Suitable carriers, excipients, or diluents are those known in the art for use in such administration methods.

[0174] The pharmaceutical compositions disclosed herein can be prepared by combining the compounds of the disclosed invention with suitable pharmaceutically acceptable excipients.

[0175] The pharmaceutical compositions disclosed herein can be manufactured using methods well known in the art, such as conventional mixing, dissolving, granulation, sugar-coated pill making, grinding, emulsification, freeze drying, etc.

[0176] In all methods of administration of the targeted peptides or pharmaceutically acceptable salts thereof, or SSTR2-binding molecules thereof, or pharmaceutical compositions thereof, the daily dose is from 0.001 to 2000 mg / kg body weight. The targeted peptides or pharmaceutically acceptable salts thereof, or SSTR2-binding molecules thereof, or pharmaceutical compositions thereof, can be prepared by a variety of synthetic methods known to those skilled in the art, including specific embodiments listed below, embodiments formed by combining them with other chemical synthetic methods, and equivalent substitutions known to those skilled in the art. Preferred embodiments include, but are not limited to, the embodiments of this disclosure.

[0177] In some embodiments, the compound or pharmaceutical composition according to or used in this application may be administered by means of a medical device or instrument such as an implant, graft, prosthesis, or stent. Additionally, implants designed to contain and release such compounds or compositions may be designed. One example is an implant made of a polymeric material suitable for releasing a compound over a period of time.

[0178] The terms “targeting peptide,” “polypeptide compound,” and “peptide compound” are used interchangeably in the context of this application and all refer to peptide compounds that can specifically interact with somatostatin receptor 2 (SSTR2).

[0179] In this application, the terms “combination” and “linkage” are used interchangeably and refer to the connection between two or more chemical parts, each with a specific function, through covalent bonds.

[0180] The terms "targeting peptide conjugate" or "binding molecule" refer to substances formed by the direct or covalent linkage of a targeting peptide or its pharmaceutically acceptable salt with a specific functional chemical group (e.g., chelating agents, complexing agents, conjugates, etc., specifically such as DOTA, DOTAGA, NODAGA, etc.) through suitable linkers (linking groups or spacers, commonly such as -PEG2-, -Phe-Asp-, etc.). In this application, the SSTR2 binding molecule or targeting peptide conjugate refers to a class of targeting peptide conjugates capable of specifically interacting with somatostatin receptor 2. The targeting peptide conjugate or SSTR2 binding molecule in this application can be a substance without radioactive or non-radioactive nuclides, or a substance with radioactive or non-radioactive nuclides. The terms "linker," "connector group," or "spacer group" refer to what is commonly known as a "linker," a molecular bridge that covalently links a polypeptide compound to other chemical groups with specific functions (such as chelating agents, complexing agents, conjugating agents, etc.). This provides a connecting bridge, modulates the properties of the polypeptide compound, and positively influences the creation of appropriate spatial spacing between the polypeptide compound and the specific functional group. The targeting peptide conjugate formed by linking the targeted peptide to a chemical group with specific functions (such as chelating agents, complexing agents, conjugating agents, etc.) through a linker in this application does not adversely affect its specific binding to SSTR2. For example, the linker in this application has a -PEG2- structure. The -D-Phe-Asp- structure is

[0181] "Alkyl" is a class of saturated aliphatic chain hydrocarbon groups, including straight-chain alkyl and branched-chain alkyl groups, which are groups formed by removing one hydrogen atom from a chain alkane molecule. For example, C1-C6 alkyl as used in this application refers to straight-chain alkyl or branched-chain alkyl groups composed of 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6, or any range of two of the aforementioned values). Typical alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, p-pentyl, n-hexyl, etc.

[0182] "Alkylene" is a class of saturated aliphatic chain hydrocarbon groups, including straight-chain alkylene and branched-chain alkylene. It refers to a group formed by removing two hydrogen atoms from an alkane molecule. The removed hydrogen atoms can be connected to the same carbon atom or different carbon atoms. In this application, C1-C6 alkylene refers to straight-chain or branched alkylene composed of 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6, or any range of two of the aforementioned values). Typical alkylenes include, but are not limited to, -CH2-, -CH(CH3)-, -CH(CH2CH3)-, -CH[CH(CH3)2]-, -CH2CH2-, and -CH(CH3)CH2-.

[0183] "Alkoxy" refers to -O-alkyl; the C1-C6 alkoxy used in this application refers to a straight-chain alkoxy or branched-chain alkoxy composed of 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6, or any range of two of the aforementioned values). Typical alkoxy groups include, but are not limited to, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentoxy, isopentoxy, pteropentoxy, and n-hexyloxy.

[0184] "Halogen" or "halogen" refers to fluorine, chlorine, bromine, or iodine.

[0185] "Halogenated alkyl" refers to an alkyl group in which at least one hydrogen atom is replaced by a halogen atom. In this application, C1-C6 halogenated alkyl refers to a straight-chain or branched alkyl group composed of 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6, or any range of two of the aforementioned values), wherein at least one hydrogen atom on the alkyl group is arbitrarily replaced by a halogen atom. Common halogenated alkyl groups include, but are not limited to, monofluoromethyl, difluoromethyl, trifluoromethyl, 1-fluoroethyl, 1,1-difluoroethyl, 2-fluoroethyl, 2,2-difluoroethyl, 1,2-difluoroethyl, 2,2,2-trifluoroethyl, monochloromethyl, dichloromethyl, trichloromethyl, 1-chloroethyl, 1,1-dichloroethyl, 2-chloroethyl, 2,2-dichloroethyl, 1,2-dichloroethyl, 2,2,2-trichloroethyl, etc.

[0186] A "ring" refers to any closed, covalently cyclic structure, including, for example, carbon rings (e.g., aromatic or alicyclic rings) and heterocyclic rings (e.g., aromatic heterocyclic or alicyclic heterocyclic rings). A carbon ring is a ring composed solely of carbon atoms, while a heterocyclic ring is a closed structure formed by the covalent bonding of carbon atoms and heteroatoms. Depending on the number of rings, a "ring" can be monocyclic, bicyclic, tricyclic, or polycyclic. When the ring is bicyclic, tricyclic, or polycyclic, the relationships between the rings can include fused rings, spirocyclic rings, and bridged rings.

[0187] "Heteroatoms" refer to any atoms other than carbon atoms that can covalently bond with carbon atoms, for example, 1 to 6, such as 1, 2, 3, 4, 5 or 6. Common heteroatoms include, but are not limited to, O, S, N, P, Si, etc., for example, 1, 2, 3, 4, 5 or 6 O, S, N or P atoms.

[0188] "Member" refers to the number of skeleton atoms that make up the ring. Typical 5-membered rings include, but are not limited to, cyclopentane, pyrrole, imidazole, thiazole, furan, and thiophene; typical 6-membered rings include, but are not limited to, cyclohexane, pyridine, pyran, pyrazine, thioran, pyridazine, pyrimidine, and benzene.

[0189] "Cycloalkyl" refers to an aliphatic cyclic group with a saturated carbon atom as its backbone. In this application, 3- to 14-membered cycloalkyl or 3- to 14-membered saturated alicyclic groups refer to cyclic groups composed of 3 to 14 saturated carbon atoms (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or any range of two of the aforementioned values).

[0190] "Heterocyclic alkyl" refers to a non-aromatic cyclic group formed by replacing carbon atoms in an alicyclic ring with one or more heteroatoms, wherein all carbon atoms constituting the cyclic skeleton of the alicyclic heterocycle are saturated. For example, the 3-14 membered saturated alicyclic heterocycles used in this application refer to non-aromatic cyclic groups formed by a cyclic skeleton composed of 3 to 14 atoms (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or any range of two of the aforementioned values), wherein the atoms constituting the cyclic skeleton consist of saturated carbon atoms and heteroatoms. Typical saturated alicyclic heterocycles include, but are not limited to:

[0191] wait.

[0192] "Aromatic heterocycle" or "heteroaryl" refers to an aromatic cyclic structure formed by the substitution of one or more heteroatoms for carbon atoms in an aromatic ring. In this application, 5- to 10-membered aromatic heterocycles or 5- to 10-membered heteroaryl groups refer to aromatic cyclic groups containing heteroatoms, consisting of 5 to 10 (e.g., 5, 6, 7, 8, 9, 10, or any range of two of the aforementioned values) skeletal atoms. Typical aromatic heterocycles or heteroaryl groups include, but are not limited to: wait.

[0193] "Parallelized rings" refer to ring structures in which two adjacent ring atoms are shared between the rings. Parallelized rings can be bicyclic, tricyclic, or polycyclic.

[0194] "Paracyl heteroaryl" refers to a cyclic structure in which two adjacent ring atoms are shared between the rings, and the entire cyclic structure is a heteroaryl group. In this application, "paracyl heteroaryl" includes, but is not limited to, […].

[0195] "Amine" or "amine" refers to a substance with the -NR group. S R T The chemical structure of R, where R S R T Each group is independently selected from hydrogen, deuterium, tritium, alkyl, and cycloalkyl groups. Common "amino groups" include, but are not limited to, -NH2, -NHCH3, -N(CH3)2, -NHCH2CH3, and -N(CH2CH3)2.

[0196] "Imine" or "imine" refers to a group with the radical NR. W The chemical structure of R, where R W It is selected from hydrogen, deuterium, tritium, alkyl, and cycloalkyl.

[0197] "Carbonyl" refers to a group with -COR Z The chemical structure of R, where R Z Selected from alkyl, cycloalkyl, and heterocycloalkyl groups, common carbonyl groups include but are not limited to -COCH3, -COCH2CH3, -CO(CH2)2CH3, and -COCH(CH3)2.

[0198] "Aminoalkyl" refers to a group in which any one hydrogen atom of an alkyl group is replaced by an amino group. In this application, C1-C6 aminoalkyl refers to a straight-chain or branched alkyl group composed of 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6, or any range of two of the aforementioned values), wherein any one hydrogen atom of the alkyl group is replaced by an amino group. Common aminoalkyl groups include, but are not limited to, -CH2N(CH3)2, -CH2NH2, -CH2NHCH3, -CH2NHCH2CH3, and -CH2N(CH2CH3)2.

[0199] "Amide alkyl" refers to a group in which any one hydrogen atom of an alkyl group is replaced by an amide group. In this application, C1-C6 amide alkyl refers to a straight-chain or branched alkyl group composed of 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6, or any range of two of the aforementioned values), wherein any one hydrogen atom of the alkyl group is replaced by an amide group. Common amide alkyl groups include, but are not limited to, -CH2NHCOCH3 and -CH2CONH2.

[0200] "Ester group" refers to a group with the formula -C(O)OR a or -OC(O)R b The chemical structure of R, where R a R b Selected from alkyl, cycloalkyl, and heterocycloalkyl groups, common ester groups include but are not limited to -C(O)OCH3, -C(O)OCH2CH3, -C(O)O(CH2)2CH3, -C(O)OCH(CH3)2, -OC(O)CH3, -OC(O)CH2CH3, -OC(O)(CH2)2CH3, and -OC(O)CH(CH3)2.

[0201] A "chelating agent" is a group having two or more coordinating atoms that can chelate with the same central atom or ion (e.g., a metal nuclide) through coordinate bonds to form a cyclic structure. This group is formed by the removal of a hydrogen atom from any carbon atom or an OH group from any carboxyl group, and then covalently linked to the parent compound via a single bond. Common chelating agents include, but are not limited to, chelating groups. EDTA (ethylenediaminetetraacetic acid) 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) N,N"-Bis[2-hydroxybenzyl]ethylenediamine-N,N"-diacetic acid (HBED) N,N"-Bis[2-hydroxy-5-(carboxyethyl)-benzyl]ethylenediamine-N,N"-diacetic acid (HBED-CC) N-2-Hydroxy-5-(Tetrafluorophenylethyl)-Benzyl-N"-2'-Hydroxy-5'-(Carboxyethyl)-Benzylethylenediamine-N,N"-Diacetic acid (HBED-CC-TFP) N,N"-Bis[3-carboxy)pyridinemethyl]ethylenediamine (DEDPA) 1,4,7-Triazacyclononane-1,4,7-triacetic acid (NOTA) 2-(4,7-bis(carboxymethyl)-1,4,7-triazol-N-alkyl-1-yl)glutaric acid (NODAGA), 2-(4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane-1-yl)-glutaric acid (DOTAGA), 1,4,8,11-Tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (TETA) 1,4,8,11-Tetraazacyclotetradecane-1,8-diacetic acid (TE2A) 4,11-bis(carboxymethyl)-1,4,8,11-tetraazabicyclo[6,6,2]hexadecane (CB-TE2A), 1,4,7-Triazacyclononane-1,4,7-trimethylphosphonic acid (TRAP) 1,4,7-Triazacyclononane-1,4,7-tris[methyl(2-hydroxymethyl)phosphonic acid](TRAP-OH), 1,4,7-Triazacyclononane-1,4,7-tris[methyl(2-carboxyethyl)phosphonic acid](TRAP-Pr), 1,4,7-Triazacyclononane-1-[methyl(2-carboxyethyl)phosphonic acid]-4,7-bis[methyl(2-hydroxymethyl)phosphonic acid] (NOPO), 3,6,9,15-Tetraazabicyclo[9,3,1]pentadecane-1(15),11,13-triene-3,6,9-triacetic acid (PCTA), Diethyltriaminepentaacetic acid (DTPA) 1,4,7,10,13-Pentazacyclopentadecane-1,4,7,10,13-pentaacetic acid (PAPA) 1,4,7,10,13,16-Hexaazacyclooctadecane-1,4,7,10,13,16-hexaacetic acid (HEHA) 10-phosphonomethyl-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3AP) 10-(2-Carboxyethyl)phosphonic acid methyl-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3APPrA) 6-Bis(carboxymethyl)amino-6-methyl-1,4-diazacycloheptane-1,4-diacetic acid (AAZTA) Macropa, Crown, α 10 -(4-Aminobutyl)-DOTA α 10 -(cyanothiophenyl)methyl-DOTA α 4,10 -(4-Aminobutyl)-DOTA α 4,10 -Dicarboxyethyl-DOTA The chelating groups in this application also include their derivatives (e.g., carboxylic acid ester derivatives).

[0202] In this application, when a letter refers to an object or quantity, it is case-sensitive.

[0203] "Substitution" refers to the independent replacement of one or more hydrogen atoms in a group by a corresponding number of substituents. It goes without saying that the substituents are only in their possible chemical positions, and those skilled in the art can determine (experimentally or theoretically) possible or impossible substitutions without much effort. For example, an amino or hydroxyl group with free hydrogen may be unstable when bonded to a carbon atom with an unsaturated bond (such as an alkene). Substituents are individually and independently selected from alkyl, cycloalkyl, aryl, heteroaryl, heterocycloalkyl, hydroxyl, alkoxy, alkylthio, aryloxy, nitro, acyl, halogen, haloalkyl, amino, etc.

[0204] "Optional" or "optionally" means that the event or circumstance described below may but not necessarily occur, and the description includes the possibility that the event or circumstance may or may not occur. For example, "optionally substituted" includes substituted or unsubstituted, and "optionally alkyl-substituted heterocyclic group" means that an alkyl group may but not necessarily be present, and the description includes cases where the heterocyclic group is substituted with an alkyl group and cases where the heterocyclic group is not substituted with an alkyl group.

[0205] Unless otherwise specified, when a group has one or more connectable sites, any one or more sites of that group can be connected to other groups by chemical bonds. When the chemical bond connection is non-directional and the connectable site contains H atoms, the number of H atoms at that site will decrease accordingly with the number of chemical bonds connected, resulting in a group with a corresponding valence. The chemical bonds connecting the site to other groups can be straight solid line bonds. Straight dashed key or wavy line express.

[0206] Suitable pharmaceutical compositions can be formulated using methods known in the art, and their administration method and dosage can be determined by a technician.

[0207] "Pharmaceutical acceptable" means that compounds, materials, compositions, and / or dosage forms are suitable for use in contact with human and animal tissues, within the limits of reliable medical judgment, without excessive toxicity, irritation, allergic reactions, or other problems or complications, in proportion to a reasonable benefit / risk ratio.

[0208] "Tautomer" or "tautomer form" refers to structural isomers of different energies that can interconvert via low-barrier transitions. For example, proton tautomers (also known as proton transfer tautomers) include interconversions via proton migration, such as keto-enol and imine-enamine isomerization. A specific example of a proton tautomer is the imidazole moiety, where a proton can migrate between two ring nitrogens. Valence tautomers include interconversions via the recombination of some bonding electrons. Non-limiting examples of tautomers include, but are not limited to,

[0209] "Stereoisomers" refer to isomers with the same molecular formula and functional groups, but different spatial arrangements of atoms or functional groups in the molecule. They include cis-trans isomers and chiral isomers. Chiral isomers are further divided into two main categories: enantiomers and diastereomers.

[0210] "Enantiomers" refer to compounds with the same molecular formula and functional groups that are isomers due to differences in the spatial arrangement of atoms or functional groups. The compounds form stereoisomers that are mirror images of each other and cannot be superimposed.

[0211] "Diarrhetinic isomers" refer to compounds with the same molecular formula and functional groups that are isomers due to different spatial arrangements of atoms, and these compounds are stereoisomers that are not mirror images of each other.

[0212] In this application, a straight covalent bond “—” in the compound structure can represent a bond that is coplanar with the paper. In this application, when the atoms connected by a straight covalent bond have stereoisomers, the arrangement of the atoms connected by the straight covalent bond can include being coplanar with the paper, facing outwards from the paper, facing inwards from the paper, or a mixture of various arrangements.

[0213] Unless otherwise specified, use wedge-shaped solid line keys. and wedge-shaped dashed key The absolute configuration of the center of a solid is represented by a straight solid line key. The relative configuration of the center of a solid.

[0214] In this application, the term "specific binding" or "specific to" refers to a selective binding behavior in which a binding molecule (e.g., the target peptide described in this application or its pharmaceutically acceptable salt, or the SSTR2 binding molecule or its conjugate) preferentially interacts with the target molecule or target receptor (e.g., the SSTR2 described in this application), while binding to other non-target molecules or non-target receptors is significantly reduced. This specific binding can be characterized by higher binding affinity, stronger binding activity, or more stable binding properties, and can effectively distinguish non-specific interactions. The term "affinity" or "binding affinity" refers to the intrinsic binding ability between a target molecule or target receptor (e.g., SSTR2) and its ligand (e.g., the target peptide described in this application or its pharmaceutically acceptable salt, or the SSTR2 binding molecule or its conjugate), which arises from the combined effect of multiple non-covalent interactions. Unless otherwise stated, the term "binding affinity" in this application is used to reflect the intrinsic binding ability of a one-to-one interaction between members of a binding pair.

[0215] In this application, "random grouping of animals according to their weight" is a routine method for conducting pharmacological experiments in the field. It is an operational step to ensure the comparability between experimental groups. Its core principle is to randomly assign animals with similar weights to each group so that the mean and distribution of weights in each group are as similar as possible, ensuring that the weights of the groups are balanced, thereby reducing the impact of individual differences on the experimental results.

[0216] Unless otherwise stated, the terms “comprise,” “comprises,” and “comprising” or their equivalents (contain, contain, containing, include, include, including) used herein are open-ended expressions, meaning that they may cover other unspecified elements, components, and steps in addition to those listed.

[0217] Unless otherwise stated, all figures used herein to represent amounts of components, measurements, or reaction conditions should be understood to be modified by the term "about" in all cases. When used with percentages, the term "about" may mean, for example, ±1%, preferably ±0.5%, more preferably ±0.1%.

[0218] Unless the context clearly indicates otherwise, singular terms in this document encompass plural referents, and vice versa. Similarly, nouns without a defined quantity also include plural referents. Unless otherwise stated, the words “a” or “an” in this document mean “at least one” or “at least one”. Unless the context clearly indicates otherwise, the word “or” in this document is intended to include “and”.

[0219] Obviously, based on the foregoing content of this application, and using ordinary technical knowledge and methods in the art, various other modifications, substitutions, or alterations can be made without departing from the basic technical concept of this application. For purposes of description and disclosure, all patents, patent applications, and other publications are expressly incorporated herein by reference. These publications are provided solely because their publication predates the filing date of this application. All statements regarding the dates of these documents or descriptions of their contents are based on information available to the applicant and do not constitute any acknowledgment of the correctness of the dates or contents of these documents. Moreover, in any country, any reference to these publications herein does not constitute an endorsement that such publication is part of the common general knowledge in the art. Attached Figure Description

[0220] Figure 1 shows 177 SPECT / CT imaging results of Lu-DOTA-JR11 in mice with NCI-H524 small cell lung cancer model;

[0221] Figure 2 shows 177 SPECT / CT imaging results of Lu-DOTA-peptide 4 in mice with NCI-H524 small cell lung cancer model;

[0222] Figure 3 shows 177 SPECT / CT imaging results of Lu-DOTA-peptide 6 in NCI-H524 small cell lung cancer model mice;

[0223] Figure 3A shows 177 Lu-DOTA-JR11 177 Lu-DOTA-peptide 4 177 Lu-DOTA-peptide 6 was used in SPECT-CT fusion images of NCI-H524 small cell lung cancer model mice. Appropriate slices were selected, and the target regions of interest were delineated using the ROI delineation tool. The images are as follows: A to C.

[0224] Figure 4 shows 177 Biodistribution of Lu-DOTA-TATE in a mouse model of NCI-H524 small cell lung cancer;

[0225] Figure 5 illustrates the application of this application. 177 Biodistribution of Lu-DOTA-peptide 1 in mice with NCI-H524 small cell lung cancer model;

[0226] Figure 6 shows 177 Biodistribution of Lu-DOTA-JR11 in a mouse model of NCI-H69 small cell lung cancer;

[0227] Figure 7 shows177 Biodistribution of Lu-DOTA peptide 4 in a mouse model of NCI-H69 small cell lung cancer;

[0228] Figure 8 shows 177 Biodistribution of Lu-DOTA-peptide 6 in a mouse model of NCI-H69 small cell lung cancer;

[0229] Figure 9 shows 68 Ga-NODAGA-JR11 and 68 PET / CT fusion image of Ga-NODAGA-peptide 6 in a human small cell lung cancer NCI-H69 cell CDX model;

[0230] Figure 10 shows 68 Ga-NODAGA-JR11 and 68 Time-activity curve of Ga-NODAGA-peptide 6 in human small cell lung cancer NCI-H69 cell CDX model;

[0231] Figure 11 shows 68 Ga-NODAGA-JR11 and 68 PET / CT fusion image of Ga-NODAGA-peptide 6 in a human small cell lung cancer NCI-H524 cell CDX model;

[0232] Figure 12 shows 68 Ga-NODAGA-JR11 and 68 Time-activity curve of Ga-NODAGA-peptide 6 in human small cell lung cancer NCI-H524 cell CDX model;

[0233] Figure 13 shows the changes in body weight of mice in different groups of NCI-H69 cell CDX model mice after drug administration;

[0234] Figure 14 shows the tumor growth inhibition in different groups of NCI-H69 cell CDX model mice after drug administration;

[0235] Figure 15 shows the survival curves of different groups of NCI-H69 cell CDX model mice after drug administration;

[0236] Figure 16 shows the changes in body weight of different groups of NCI-H524 cell CDX model mice after drug administration;

[0237] Figure 17 shows the tumor growth inhibition in different groups of NCI-H524 cell CDX model mice after drug administration;

[0238] Figure 18 shows the survival curves of different groups of NCI-H524 cell CDX model mice after drug administration. Detailed Implementation

[0239] The somatostatin analogue of this application exhibits comparable or even higher in vitro activity compared to existing somatostatin analogues such as TATE (Tyr3-octreotate). Furthermore, while maintaining comparable in vitro activity, the radiolabeled somatostatin, when linked to a chelating agent or linked via a linker or spacer, displays better tumor specificity. On the one hand, it shows a high enrichment rate in tumor cells, such as small cell lung cancer cells; on the other hand, its uptake in other normal non-target organs is very low. The somatostatin analogue of this application can further increase tumor uptake or decrease uptake in normal tissues by modifying or adding certain linkers or spacers, thereby achieving greater advantages in biodistribution and efficacy.

[0240] Example

[0241] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0242] Reagent abbreviations:

[0243] In the specific implementation of this application, amino acids without a specified configuration or amino acids linked to protecting groups (e.g., Fmoc, Boc, etc.) are all L-type. In this application, CTC-peptide represents a polypeptide intermediate adsorbed on CTC resin when synthesized as the polypeptide of this application, with Fmoc protection removed but other protecting groups (e.g., hydroxyl protecting group tBu, amino protecting group Boc) not removed; AM-peptide represents a polypeptide intermediate adsorbed on AM resin when synthesized as the polypeptide of this application, with Fmoc protection removed but other protecting groups (e.g., hydroxyl protecting group tBu, amino protecting group Boc) not removed. Specifically, for example, CTC-peptide1 represents polypeptide 1 intermediate adsorbed on CTC resin, with Fmoc protection removed but other protecting groups (e.g., hydroxyl protecting group tBu, amino protecting group Boc) not removed; CTC-TATE represents TATE intermediate adsorbed on CTC resin, with Fmoc protection removed but other protecting groups (e.g., hydroxyl protecting group tBu, amino protecting group Boc) not removed. The CTC-peptide or AM-peptide in this application is obtained by dissociating it from the resin with a reagent to obtain a peptide compound. For example, CTC-TATE is obtained by dissociating it from the resin to obtain TATE.

[0244] Preparation Example 1: Synthesis of Fmoc-4-dihydroxyboryl-D-Phe-OH

[0245] Fmoc-D-4-bromo-Phe-OH (5 g, 10.7 mmol) was dissolved in 2-MeTHF (208 mL), and tris(o-methylphenyl)phosphine (326 mg, 1.07 mmol) was added sequentially, with the system purged with nitrogen three times. Then, tetrahydroxydiborane (1.92 g, 21.4 mmol) was added, followed by potassium acetate (3.16 g, 32.2 mmol) after 10 min, and then Pd(OAc)₂ (120 mg, 0.54 mmol) and MeOH (83.2 mL) after another 10 min. The mixture was heated to 50 °C and reacted overnight. After the reaction was complete, 1 N hydrochloric acid was added to adjust the pH to 2. After separation, the organic phase was washed twice with saturated brine, and the combined organic phases were purified by column chromatography (eluting with 100% ethyl acetate) to give 6.04 g of the title compound. LC-MS theoretical value: 431.2, measured value: [M-Fmoc+H] + :210.1.

[0246] Comparative Example 1: Preparation of TATE

[0247] After swelling CTC resin (1 mmol) with DMF, Fmoc-Thr(tBu)-OH (2 mmol) and DIEA (4 mmol) solution dissolved in DMF (20 mL) were added and reacted for 2 h. Then, MeOH (1 mL) was added and the reaction continued for more than 1 h to complete the end-capping. Fmoc-Cys(Trt)-OH (3 mmol), Oxyma (3 mmol), and DIC (3 mmol) were dissolved in DMF (25 mL) for activation. After 5 min, the resin was added and reacted for more than 1 h. The resin showed a negative result for ninhydrin detection (the resin was transparent and colorless), and the reaction solution was drained. The resin was washed 3 times with DMF, and then washed 6 times with 20% piperidine / DMF solution (25 mL) to remove the Fmoc protecting group. Repeat the above steps, using the following amino acid sequences sequentially: Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-Trp(Boc)-OH, Fmoc-Tyr(tBu)-OH, Fmoc-Cys(Trt)-OH, and Fmoc-D-Phe to synthesize the peptide chain. Then, I2 (3 mmol) dissolved in DMF (25 mL) was added to the resin. After reacting for 1 h, the reaction solution was drained and the resin was washed 6 times to complete the ring closure. The resin was washed twice with DCM (25 mL), and then contracted with MeOH (25 mL). The resin was dissociated using TFA (40 mL, containing 5% TIS) for 2 h, then filtered, the filtrate was collected, and concentrated under reduced pressure. Add 100 mL of MTBE at 0°C to the concentrate. A white solid precipitates; centrifuge and discard the supernatant. Add another 100 mL of MTBE at 0°C to the solid, stir to mix, centrifuge again, discard the supernatant, and dry the remaining solid. Purify the crude product using preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20 mL / min, elution gradient: 5%-95%). Lyophilize the preparative solution containing the product to obtain a white solid product, TATE (87 mg). LC-MS: Theoretical value: 1048.4, Measured value: [M+H] + :1049.8,[(M+2H) / 2] + :525.0.

[0248] Example 1: Synthesis of polypeptide 1

[0249] Following the synthetic method described in Comparative Example 1, polypeptide 1 was synthesized by amino acid condensation using Oxyma and DIC, followed by deprotection of the Fmoc protecting group with 20% piperidine / DMF solution, disulfide cyclization with I2, and then dissociation from the resin using TFA (40 mL, containing 5% TIS). The amino acid sequences were, in order: Fmoc-Thr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-Trp(Boc)-OH, Fmoc-4-Pal-OH, Fmoc-Cys(Trt)-OH, and Fmoc-D-Phe. Finally, the crude MTBE solid was purified by preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN; flow rate: 20mL / min; elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain peptide 1 (37mg). LC-MS: theoretical value: 1033.4, measured value: [M+H] + :1034.8,[(M+2H) / 2] + :517.5.

[0250] Example 2: Synthesis of polypeptide 2

[0251] Following the synthetic method described in Comparative Example 1, polypeptide 2 was synthesized using amino acid condensation with Oxyma and DIC, followed by deprotection of the Fmoc protecting group with 20% piperidine / DMF solution, disulfide cyclization with I2, and then dissociation from the resin using TFA (40 mL, containing 5% TIS). The amino acid sequences were, in order: Fmoc-Thr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-3-benzothiophene alanine, Fmoc-Tyr(tBu)-OH, Fmoc-Cys(Trt)-OH, and Fmoc-D-Phe. Finally, the crude MTBE solid was purified by preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN; flow rate: 20mL / min; elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain peptide 2 (28mg). LC-MS theoretical value: 1065.4, measured value: [M+H] + :1066.7,[(M+2H) / 2] + :533.5.

[0252] Example 3: Synthesis of polypeptide 3

[0253] Following the synthesis method in Comparative Example 1, polypeptide 3 was synthesized by amino acid condensation using Oxyma and DIC, followed by deprotection of the Fmoc protecting group with 20% piperidine / DMF solution, disulfide cyclization with I2, and then dissociation from the resin using TFA (40 mL, containing 5% TIS). The amino acid sequences were, in order: Fmoc-Thr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-β-(1-piperazinyl)-Ala(Boc)-OH, Fmoc-D-Trp(Boc)-OH, Fmoc-Tyr(tBu)-OH, Fmoc-Cys(Trt)-OH, and Fmoc-D-Phe. Finally, the crude MTBE solid was purified by preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN; flow rate: 20mL / min; elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain peptide 3 (37mg). LC-MS theoretical value: 1075.4, measured value: [M+H] + :1075.8,[(M+2H) / 2] + :538.5.

[0254] Comparative Example 2: Synthesis of JR11

[0255] After swelling AM resin (1 mmol) with DMF, the resin was washed 6 times after removing the Fmoc protecting group with 20% piperidine / DMF solution (25 mL). Fmoc-D-Tyr(tBu)-OH (3 mmol), Oxyma (3 mmol), and DIC (3 mmol) were dissolved in DMF (25 mL) for activation. After 5 min, the solution was poured into the resin and reacted for at least 1 h. The resin was then drained after a negative ninhydrin test (the resin was transparent and colorless). The resin was washed 3 times with DMF, and then washed 6 times again after removing the Fmoc protecting group with 20% piperidine / DMF solution (25 mL). The above steps were repeated, using the following compounds sequentially: Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-Aph(Cbm)-OH, Fmoc-Aph(Hor)-OH, Fmoc-D-Cys(Trt)-OH, and Fmoc-4-chlorophenylalanine to synthesize the peptide chain. I2 (3 mmol, 3.0 eq.) was then dissolved in DMF (25 mL) and added to the resin for reaction. After 1 h, the reaction solution was drained and the resin was washed 6 times to complete the ring closure. The resin was washed twice with DCM (25 mL), and then condensation was completed with MeOH (25 mL). The resin was then dissociated using TFA (40 mL, containing 5% TIS) for 2 h, followed by filtration, collection of the filtrate, and concentration under reduced pressure. Adding 100 mL of MTBE at 0°C to the concentrate resulted in the precipitation of a white solid. Centrifugation was performed, and the supernatant was discarded. Then, 100 mL of MTBE at 0°C was added to the solid, stirred, and centrifuged again. The supernatant was discarded, and the remaining solid was dried. The crude solid was purified by preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20 mL / min, elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain a white solid product JR11 (20 mg). LC-MS theoretical value: 1301.4, measured value: [(M+2H) / 2] + :651.5.

[0256] Comparative Example 3: Synthesis of LM3

[0257] Following the synthesis method in Comparative Example 2, polypeptide LM3 was synthesized by amino acid condensation using Oxyma and DIC, followed by deprotection of the Fmoc protecting group with 20% piperidine / DMF solution, disulfide cyclization with I2, and then dissociation from the resin using TFA (40 mL, containing 5% TIS). The amino acid sequences were Fmoc-D-Tyr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-Aph(Cbm)-OH, Fmoc-Tyr(tBu)-OH, Fmoc-D-Cys(Trt)-OH, and Fmoc-4-chlorophenylalanine. Finally, the crude MTBE solid was purified by preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20mL / min, elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain a white solid product LM3 (26mg). LC-MS: theoretical value: 1162.4, measured value: [M+H] + :1163.7,[(M+2H) / 2] + :582.0.

[0258] Example 4: Synthesis of polypeptide 4

[0259] Following the synthetic method described in Comparative Example 2, polypeptide 4 was synthesized using amino acid condensation with Oxyma and DIC, followed by deprotection of the Fmoc protecting group with 20% piperidine / DMF solution, disulfide cyclization with I2, and then dissociation from the resin using TFA (40 mL, containing 5% TIS). The amino acid sequences were, in order: Fmoc-D-Tyr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-Aph(Cbm)-OH, Fmoc-4-Borono-L-Phe-OH, Fmoc-D-Cys(Trt)-OH, and Fmoc-4-Chlorophenylalanine. Finally, the crude solid precipitated from MTBE was purified by preparative HPLC (column: UniSil 10-100 C18 10μm 21.2x 250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20mL / min, elution gradient: 5%–95%). The preparative solution containing the product was lyophilized to obtain peptide 4 (41mg). LC-MS: theoretical value: 1190.4, measured value: [(M+2H) / 2] +:596.0.

[0260] Example 5: Synthesis of polypeptide 5

[0261] Following the synthesis method in Comparative Example 2, polypeptide 5 was synthesized by amino acid condensation using Oxyma and DIC, followed by deprotection of the Fmoc protecting group with 20% piperidine / DMF solution, disulfide cyclization with I2, and then dissociation from the resin using TFA (40 mL, containing 5% TIS). The amino acid sequences were Fmoc-D-Tyr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-4-Borono-D-Phe-OH, Fmoc-Tyr(tBu)-OH, Fmoc-D-Cys(Trt)-OH, and Fmoc-4-chlorophenylalanine. Finally, the crude MTBE solid was purified by preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20mL / min, elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain peptide 5 (18mg). LC-MS theoretical value: 1148.4, measured value: [(M+2H) / 2] + :574.9.

[0262] Example 6: Synthesis of polypeptide 6

[0263] Following the synthetic method described in Comparative Example 2, polypeptide 6 was synthesized using amino acid condensation with Oxyma and DIC, followed by deprotection of the Fmoc protecting group with 20% piperidine / DMF solution, disulfide cyclization with I2, and then dissociation from the resin using TFA (40 mL, containing 5% TIS). The amino acid sequences were, in order: Fmoc-4-Borono-D-Phe-OH, Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Lys(Boc)-OH, Fmoc-D-Aph(Cbm)-OH, Fmoc-Tyr(tBu)-OH, Fmoc-D-Cys(Trt)-OH, and Fmoc-4-Chlorophenylalanine. Finally, the crude MTBE solid was purified by preparative HPLC (column: UniSil 10-100 C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20mL / min, elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain 6 (27mg) of white solid product. LC-MS theoretical value: 1190.4, measured value: [(M+2H) / 2] + :596.9.

[0264] Examples 7 to 21:

[0265] Following a solid-phase polypeptide synthesis method similar to that described in the above embodiments (e.g., referring to the synthesis method in Comparative Example 1 or Comparative Example 2), and based on the amino acid sequence of the polypeptide, using appropriate commercial reagents, commercial amino acids (or protected amino acids such as Fmoc and Boc), or amino acids prepared according to existing literature (or protected amino acids such as Fmoc and Boc) as raw materials, polypeptide compounds 7-21 of this application were prepared. The structural and characterization data of the prepared exemplary compounds are shown in Table 1 below.

[0266] Table 1

[0267] Preparation Example 2: Synthesis of DOTA-peptide 1

[0268] The chelating agent DOTA and peptide 1 were linked using a solid-phase synthesis method. Specifically, CTC-peptide 1 (0.2 mmol) was swollen with DMF, followed by the addition of DOTA-tri(t-butyl ester) (0.6 mmol), Oxyma (0.6 mmol), and DIC (0.6 mmol) solutions dissolved in DMF (10 mL) and reacted for at least 2 hours. The reaction mixture was drained after a negative ninhydrin test (the resin was transparent and colorless). The resin was washed twice with DMF, then three times with DCM, and finally condensed with MeOH (25 mL). Resin dissociation was performed using TFA (40 mL, containing 5% TIS) for at least 12 hours, followed by filtration and concentration under reduced pressure. 100 mL of MTBE at 0°C was added to the concentrate, resulting in the precipitation of a white solid. The mixture was centrifuged, and the supernatant was discarded. Another 100 mL of MTBE at 0°C was added to the solid, mixed, centrifuged, and the supernatant was discarded. The remaining solid was then dried. The crude product was purified by preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20mL / min, elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain a white solid product, DOTA-peptide 1 (37mg). LC-MS: theoretical value: 1419.6, measured value: [(M+2H) / 2] + :710.9.

[0269] Preparation Example 3: Synthesis of DOTA-TATE

[0270] The chelating agent DOTA and the peptide TATE were linked using a solid-phase synthesis method. Specifically, CTC-TATE (0.2 mmol) was swollen with DMF, followed by the addition of DOTA-tri(t-butyl ester) (0.6 mmol), Oxyma (0.6 mmol), and DIC (0.6 mmol) solutions dissolved in DMF (10 mL) and reacted for at least 2 hours. The reaction mixture was drained after a negative ninhydrin test (the resin was transparent and colorless). The resin was washed twice with DMF, then three times with DCM, and finally condensed with MeOH (25 mL). Dissociation from the resin was performed using TFA (40 mL, containing 5% TIS) for at least 12 hours, followed by filtration and concentration under reduced pressure. 100 mL of MTBE at 0°C was added to the concentrate, resulting in the precipitation of a white solid. The mixture was centrifuged, and the supernatant was discarded. Another 100 mL of MTBE at 0°C was added to the solid, mixed, centrifuged again, and the supernatant was discarded. The remaining solid was then dried. The crude solid product was purified by preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20mL / min, elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain a white solid product, DOTA-TATE (51mg). LC-MS theoretical value: 1434.6, measured value: [(M+2H) / 2] 2+ :718.4.

[0271] Preparation Examples 4-20: Synthesis of DOTA-peptides according to this application

[0272] Following the same solid-phase synthesis method as in Preparation Examples 2 and 3, DOTA-tri (t-butyl ester) was used to form an amide bond with the terminal amino group of CTC-peptide or AM-peptide through a condensation reaction. The remaining protecting group was then eluted from the resin, completing the direct linking of the peptide according to this application to the chelating agent DOTA via its terminal amino group. This included peptides 2, 3, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, and 21, thus yielding DOTA-peptide 2 (LC-MS theoretical value: 1451.6, measured value: [(M+H)]). + :1452.8), DOTA-peptide 3 (LC-MS theoretical value: 1461.6, measured value: [(M+H)] + :1462.8), DOTA-peptide 7 (LC-MS theoretical value: 1445.6, measured value: [(M+H)] +:1446.7), DOTA-peptide 8 (LC-MS theoretical value: 1514.6, measured value: [(M+H)] + :1515.8), DOTA-peptide 9 (LC-MS theoretical value: 1469.6, measured value: [(M+H)] + :1470.8), DOTA-peptide 10 (LC-MS theoretical value: 1419.6, measured value: [(M+H)] + :1420.8), DOTA-peptide 11 (LC-MS theoretical value: 1419.6, measured value: [(M+H)] + :1420.8), DOTA-peptide 12 (LC-MS theoretical value: 1435.6, measured value: [(M+H)] + :1436.8), DOTA-peptide 13 (LC-MS theoretical value: 1469.6, measured value: [(M+H)] + :1470.8), DOTA-peptide 14 (LC-MS theoretical value: 1469.6, measured value: [(M+H)] + :1470.8), DOTA-peptide 15 (LC-MS theoretical value: 1449.6, measured value: [(M+H)] + :1450.8), DOTA-peptide 16 (LC-MS theoretical value: 1462.6, measured value: [(M+H)] + :1463.8), DOTA-peptide 17 (LC-MS theoretical value: 1487.6, measured value: [(M+H)] + :1488.8), DOTA-peptide 18 (LC-MS theoretical value: 1449.6, measured value: [(M+H)] + :1450.8), DOTA-peptide 19 (LC-MS theoretical value: 1487.6, measured value: [(M+H)] + :1488.8), DOTA-peptide 20 (LC-MS theoretical value: 1433.6, measured value: [(M+H)] + :1434.8), DOTA-peptide 21 (LC-MS theoretical value: 1433.6, measured value: [(M+H)] + :1434.8).

[0273] Preparation Example 21: Synthesis of DOTA-peptide 4

[0274] The chelating agent DOTA and peptide 4 were linked using a solid-phase synthesis method. Specifically, AM-peptide 4 (0.2 mmol) was swollen with DMF, followed by the addition of DOTA-tri(t-butyl ester) (0.6 mmol), Oxyma (0.6 mmol), and DIC (0.6 mmol) solutions dissolved in DMF (10 mL) and reacted for at least 2 hours. The reaction mixture was drained after a negative ninhydrin test (the resin was transparent and colorless). The resin was washed twice with DMF, then three times with DCM, and finally shrank and dried with MeOH (25 mL). Dissociation from the resin was performed using TFA (40 mL, containing 5% TIS) for at least 12 hours, followed by filtration and concentration under reduced pressure. 100 mL of MTBE at 0°C was added to the concentrate; after a white solid precipitated, the mixture was centrifuged and the supernatant was discarded. Another 100 mL of MTBE at 0°C was added to the solid, mixed, centrifuged, and the supernatant was discarded. The remaining solid was then dried. The crude solid product was purified by preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20mL / min, elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain the white solid product DOTA-peptide 4. LC-MS theoretical value: 1576.6, measured value: [(M-36+2H) / 2] + :771.3.

[0275] Preparation Example 22: Synthesis of DOTA-Peptide 6

[0276] The chelating agent DOTA and peptide 6 were linked using a solid-phase synthesis method. Specifically, AM-peptide 6 (0.2 mmol) was swollen with DMF, followed by the addition of DOTA-tri(t-butyl ester) (0.6 mmol), Oxyma (0.6 mmol), and DIC (0.6 mmol) solutions dissolved in DMF (10 mL) and reacted for at least 2 hours. The reaction mixture was drained after a negative ninhydrin test (the resin was transparent and colorless). The resin was washed twice with DMF, then three times with DCM, and finally shrunken and dried with MeOH (25 mL). Dissociation from the resin was performed using TFA (40 mL, containing 5% TIS) for at least 12 hours, followed by filtration and concentration under reduced pressure. 100 mL of MTBE at 0°C was added to the concentrate; after the precipitation of a white solid, the mixture was centrifuged and the supernatant was discarded. Another 100 mL of MTBE at 0°C was added to the solid, mixed, centrifuged, and the supernatant was discarded. The remaining solid was then dried. The crude solid product was purified by preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20mL / min, elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain the white solid product DOTA-peptide 6. LC-MS theoretical value: 1576.6, measured value: [(M-36+2H) / 2] + :771.3.

[0277] Preparation Example 23: 175 Synthesis of Lu-DOTA-peptide 4

[0278] Weigh 20 mg (1.0 eq.) of DOTA-peptide 4 solid and dissolve it in 0.25 M sodium acetate buffer (pH = 5.0, 4 mL). Add 3.0 eq. of lutetium chloride hexahydrate solid, and then heat and stir at 95 °C for 30 min. After cooling, the reaction solution is directly purified by preparative HPLC (column: UniSil 10-100C18 5 μm 21.2 × 250 mm; mobile phase: A - 0.1% TFA solution, B - 0.1% ACN, flow rate: 20 mL / min, elution gradient: 5%-95%). The preparative solution containing the product is lyophilized to obtain a white solid product. 175 Lu-DOTA-peptide 4. LC-MS theoretical value: 1748.5, measured value: [(M+2H) / 2] + :875.6.

[0279] Preparation Example 24: 139 Synthesis of La-DOTA-peptide 6

[0280] Weigh 40 mg (1.0 eq.) of DOTA-peptide 6 solid and dissolve it in 0.25 M sodium acetate buffer (pH = 5.0, 6 mL). Add 5.0 eq. of lanthanum nitrate hexahydrate solid and heat at 55 °C with stirring for 1 h. After cooling, the reaction solution is directly purified by preparative HPLC (column: UniSil 10-100C 185 μm 21.2 × 250 mm; mobile phase: A - 0.1% TFA solution, B - 0.1% ACN, flow rate: 20 mL / min, elution gradient: 5%-95%). The preparative solution containing the product is lyophilized to obtain a white solid product. 139 La-DOTA-peptide 6. LC-MS theoretical value: 1712.5, measured value: [M+H] + :1713.5; [(M+2H) / 2] + :857.4.

[0281] Preparation Example 25: Synthesis of NODAGA-peptide 6

[0282] The chelating agent NODAGA was linked to peptide 6 using a solid-phase synthesis method. Specifically, AM-peptide 6 (0.2 mmol) was swollen with DMF, and then NODAGA-tri(t-butyl ester) (0.6 mmol), Oxyma (0.6 mmol), and DIC (0.6 mmol) dissolved in DMF (10 mL) were added and reacted for at least 2 hours. After the resin showed a negative result for ninhydrin detection (the resin was transparent and colorless), the reaction solution was drained. The resin was washed twice with DMF, then three times with DCM, and finally shrank and dried with MeOH (25 mL). Dissociation from the resin was performed using TFA (40 mL, containing 5% TIS) for at least 12 hours, followed by filtration and concentration under reduced pressure. MTBE (100 mL) at 0°C was added to the concentrate, and after the white solid precipitated, the mixture was centrifuged and the supernatant was discarded. MTBE (100 mL) at 0°C was then added to the solid, mixed, centrifuged, the supernatant was discarded, and the remaining solid was dried. The crude solid product was purified by preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20mL / min, elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain the white solid product NODAGA-peptide 6. LC-MS theoretical value: 1547.6, measured value: [(M-36+2H) / 2] + :756.8.

[0283] Preparation Example 26: Synthesis of Ga-NODAGA-peptide 6

[0284] Weigh 25 mg (1.0 eq.) of NODAGA-peptide 6 solid and dissolve it in 0.25 M sodium acetate buffer (pH = 4.0-4.5, 5 mL). Add the prepared gallium trichloride (2.0 eq.) solution (5 mg / mL in 0.1 M HCl), and then heat and stir at 95 °C for 15 min. After cooling, the reaction solution is directly purified by preparative HPLC (column: UniSil 10-100C18 5 μm 21.2 × 250 mm; mobile phase: A - 0.1% TFA solution, B - 0.1% ACN, flow rate: 20 mL / min, elution gradient: 5%-95%). The preparative solution containing the product is lyophilized to obtain the white solid product Ga-DOTA-peptide 6. LC-MS theoretical value: 1613.5, measured value: [M+H] + :1614.5; [(M+2H) / 2] + :807.7.

[0285] Preparation Example 27: Synthesis of DOTAGA-peptide 1

[0286] Following the synthesis procedure of DOTA-peptide 1 in Preparation Example 2, the connection between DOTAGA (tetra-tert-butyl ester) and CTC-peptide 1 was completed using solid-phase synthesis. After cleavage from the resin, a crude solid was precipitated with MTBE. This crude product was purified by reversed-phase preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20mL / min, elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain the white solid product DOTAGA-peptide 1. LC-MS theoretical value: 1491.6, measured value: [(M+2H) / 2] + :746.8.

[0287] Preparation Example 28: Synthesis of DOTA-PEG2-peptide 1

[0288] Following the synthesis procedure of DOTA-peptide 1 in Preparation Example 2, the linkage of peptide 1 with PEG2 and the chelating agent DOTA was completed using a solid-phase synthesis method. Specifically, after swelling CTC-peptide 1 (0.2 mmol) with DMF, a solution of 1-(9H-fluorene-9-yl)-3-oxo-2,7,10-trioxa-4-azatridecane-13-acid (0.6 mmol), Oxyma (0.6 mmol), and DIC (0.6 mmol) dissolved in DMF (10 mL) was added and reacted for more than 2 hours. After the ninhydrin test showed a negative result on the resin (the resin was transparent and colorless), the reaction solution was drained and the resin was washed 5 times with DMF. The resin was washed six times after removing the Fmoc protecting group with 10 mL of 20% piperidine / DMF solution. Then, a solution of DOTA-tri(t-butyl ester) (0.6 mmol), Oxyma (0.6 mmol), and DIC (0.6 mmol) dissolved in 10 mL of DMF was added, and the reaction was allowed to proceed for at least 2 hours. The resin was then drained after a negative ninhydrin test (the resin was transparent and colorless). The resin was washed twice with DMF, then three times with DCM, and finally condensed with 25 mL of MeOH. The resin was then dissociated using 40 mL of TFA (containing 5% TIS) for at least 12 hours. The filtrate was collected and concentrated under reduced pressure. 100 mL of 0°C MTBE was added to the concentrate, and after the white solid precipitated, the mixture was centrifuged and the supernatant was discarded. 100 mL of 0°C MTBE was then added to the solid, mixed, centrifuged, and the supernatant was discarded. The remaining solid was dried. The crude product was purified by preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20mL / min, elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain the white solid product DOTA-PEG2-peptide 1. LC-MS: theoretical value: 1578.7, measured value: [(M+2H) / 2] + :789.9.

[0289] Preparation Example 29: Synthesis of DOTA-D-Phe-Asp-peptide 1

[0290] Following the synthesis procedure of DOTA-peptide 1 in Preparation Example 2, the linkage of peptide 1 with D-Phe-Asp and the chelating agent DOTA was completed using a solid-phase synthesis method. Specifically, after swelling CTC-peptide 1 (0.2 mmol) with DMF, a solution of Fmoc-Asp(OtBu)-OH (0.6 mmol), Oxyma (0.6 mmol), and DIC (0.6 mmol) dissolved in DMF (10 mL) was added and reacted for more than 2 hours. After the ninhydrin detection resin showed a negative result (the resin was transparent and colorless), the reaction solution was drained and the resin was washed 5 times with DMF. The resin was washed 6 times after removing the Fmoc protecting group with 10 mL of 20% piperidine / DMF solution. Then, a solution of Fmoc-D-Phe-OH (0.6 mmol), Oxyma (0.6 mmol), and DIC (0.6 mmol) dissolved in 10 mL of DMF was added, and the mixture was reacted for at least 2 hours. After the resin showed a negative result for ninhydrin (the resin was clear and colorless), the reaction solution was drained, and the resin was washed 5 times with DMF. The resin was then washed 6 times with 10 mL of 20% piperidine / DMF solution after removing the Fmoc protecting group. The resin was then washed 2 times with DMF, 3 times with DCM, and finally, 25 mL of MeOH was added to complete the shrinkage. Resin dissociation was performed using TFA (40 mL, containing 5% TIS) for at least 12 hours. The filtrate was then collected and concentrated under reduced pressure. 100 mL of MTBE at 0°C was added to the concentrate, resulting in the precipitation of a white solid. The precipitate was centrifuged, and the supernatant was discarded. Another 100 mL of MTBE at 0°C was added to the solid, and after mixing and centrifugation, the supernatant was discarded. The remaining solid was dried. The crude product was purified by preparative HPLC (column: UniSil 10-100C18 10 μm 21.2 × 250 mm; mobile phase: A - 0.1% TFA solution, B - 0.1% ACN, flow rate: 20 mL / min, elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain the white solid product DOTA-D-Phe-Asp-peptide 1. LC-MS: Theoretical value: 1681.7, Measured value: [(M+2H) / 2] + :841.8.

[0291] Preparation Example 30: Synthesis of DOTAGA-PEG2-peptide 1

[0292] Following the synthesis procedure of DOTA-PEG2-peptide 1 in Preparation Example 28, CTC-peptide 1 was sequentially linked to 1-(9H-fluorene-9-yl)-3-oxo-2,7,10-trioxa-4-azatridecane-13-acid and DOTAGA (tetra-tert-butyl ester) using solid-phase synthesis. After cleavage from the resin, a crude solid was precipitated with MTBE. This crude product was purified by reversed-phase preparative HPLC (column: UniSil 10-100C18 10μm 21.2×250mm; mobile phase: A-0.1% TFA solution, B-0.1% ACN, flow rate: 20mL / min, elution gradient: 5%-95%). The preparative solution containing the product was lyophilized to obtain the white solid product DOTAGA-PEG2-peptide 1. LC-MS theoretical value: 1650.7, measured value: [(M+2H) / 2] + :826.3.

[0293] Preparation Example 31: Synthesis of DOTA-JR11, DOTA-LM3, NODAGA-JR11, and NODAGA-LM3

[0294] DOTA-JR11, DOTA-LM3, NODAGA-JR11, and NODAGA-LM3 were prepared using methods similar to those used in Preparation Examples 21 and 25.

[0295] Experimental Example 1: In vitro activity assay of peptides

[0296] In vitro experiments testing the SSTR2 receptor agonistic activity of α, TATE, the peptide of this application, and its DOTA conjugate.

[0297] 1. Reagents and Consumables

[0298] 1.1 Cell line: Flp-In-CHO-SSTR2 stable pool cells

[0299] 1.2 Complete culture medium: Ham's F-12K + 10% FBS + 1×Penicillin-Streptomycin (PS) + 600 μg / mL Hygromycin B

[0300] 1.3 Cell seeding medium: Ham's F-12K + 10% FBS

[0301] 1.4 Detection buffer: 1×HBSS + 20mM HEPES + 0.1% BSA + 500μM IBMX

[0302] 1.5 The sources of reagents and consumables are shown in Table A:

[0303] Table A

[0304] 2. Experimental Methods

[0305] 2.1 Flp-In-CHO-SSTR2 stable pool cells were cultured in complete medium at 37°C and 5% CO2 to maintain cell density in a sub-confluence state;

[0306] 2.2 Cells were seeded at a rate of 7 K / 25 μL / well in 384-well plates (Perkin Elmer, 6007680) and cultured overnight at 37°C with 5% CO2.

[0307] 2.3 After the culture is complete, remove the cell culture plate, remove the culture medium, and quickly add 15 μL of detection buffer to the experimental detection wells;

[0308] 2.4 Prepare 8× of the analyte compound and 8× of forskolin (4 μM) using the detection buffer;

[0309] 2.5 Add 2.5 μL of the 8× working solution of the test compound to the cell culture plate and incubate at 37°C for 10 min;

[0310] 2.6 Add 2.5 μL of 8×forskolin working solution to the cell culture plate and incubate at 37°C for 30 min;

[0311] 2.7 Dilute Eu-cAMP tracer and Ulight-anti-cAMP with cAMP detection buffer;

[0312] 2.8 Add 10 μL of Eu-cAMP tracer to the cell plate, followed by 10 μL of Ulight-anti-cAMP;

[0313] 2.9 Incubate at room temperature for 1 hour, then use an Envision 2105 plate reader to detect the wavelength values ​​at 665nm and 615nm.

[0314] 3. Data Analysis Methods

[0315] The data was calculated using the following formula and plotted as a curve. After fitting, EC was calculated. 50 value:

[0316] 3.1 Z'factor=1-3*(SDMax+SDMin) / (MeanMax-MeanMin);

[0317] 3.2 CVMax=(SDMax / MeanMax)*100%;

[0318] 3.3 CVMin=(SDMin / MeanMin)*100%;

[0319] 3.4 S / B = Signal / Background;

[0320] 3.5 EC 50 Equation for calculating the value:

[0321] Y=Bottom+(Top-Bottom) / (1+10^((LogEC50-X)*HillSlope))

[0322] X: Logarithm of compound concentration; Y: Activity percentage.

[0323] 4. Experimental Results

[0324] The peptides of this application possess a well-defined in vitro cell-binding affinity for SSTR2. Certain peptides of this application exhibit excellent agonistic activity against the SSTR2 receptor; for example, peptide 3 of this application demonstrates superior in vitro agonistic activity compared to TATE and natural somatostatin (peptide 3, EC50). 50 =0.205nM; TATE, EC 50 =0.522nM; Somatostatin 14, EC 50 =1.765 nM), the in vitro agonistic activities of peptides 1 and 2 of this application are similar to those of TATE, and are still far superior to the in vitro agonistic activities of natural somatostatin (peptide 1, EC50 = 1.765 nM). 50 =0.522nM; polypeptide 2, EC 50 =0.539nM); and its affinity activity is not affected after being linked to a chelating agent, and is even improved to a certain extent (DOTA-TATE, EC). 50 =0.278 nM; DOTA-peptide 1, EC 50 =0.343 nM; DOTA-peptide 9, EC 50 =0.398nM; DOTA-peptide 12, EC 50 =0.495nM; DOTA-peptide 14, EC 50 =0.463 nM; DOTAGA-peptide 1, EC 50 =0.423 nM; DOTA-PEG2-peptide 1, EC 50 =0.412 nM; DOTAGA-PEG2-peptide 1, EC 50 =0.379nM).

[0325] Test b: Test of SSTR2 receptor antagonistic activity of JR11, LM3, the peptide of this application and its conjugates.

[0326] 1. Reagents and Consumables

[0327] 1.1 Cell line: Flp-In-CHO-SSTR2 stable pool cells

[0328] 1.2 Complete culture medium: Ham's F-12K + 10% FBS + 1×Penicillin-Streptomycin (PS) + 600 μg / mL Hygromycin B

[0329] 1.3 Cell seeding medium: Ham's F-12K + 10% FBS

[0330] 1.4 Detection buffer: 1×HBSS + 20mM HEPES + 0.1% BSA + 500μM IBMX

[0331] 1.5 The sources of reagents and consumables are shown in Table A.

[0332] 2. Experimental Methods

[0333] 2.1 Flp-In-CHO-SSTR2 stable pool cells were cultured in complete medium at 37°C and 5% CO2 to maintain cell density in a sub-confluence state;

[0334] 2.2 Cells were seeded at a rate of 7 K / 25 μL / well in 384-well plates (Perkin Elmer, 6007680) and cultured overnight at 37°C with 5% CO2.

[0335] 2.3 After the culture is complete, remove the cell culture plate, remove the culture medium, and quickly add 15 μl of detection buffer to the experimental detection well;

[0336] 2.4 Prepare 8× of the analyte compound and 8× of forskolin (4 μM) & Somatostatin 14 (32 nM) using detection buffer;

[0337] 2.5 Add 2.5 μL of the 8× working solution of the test compound to the cell culture plate and incubate at 25°C for 20 min;

[0338] 2.6 Add 2.5 μL of 8×forskolin & Somatostatin 14 working solution to the cell culture plate and incubate at 37°C for 30 min;

[0339] 2.7 Dilute Eu-cAMP tracer and Ulight-anti-cAMP with cAMP detection buffer;

[0340] 2.8 Add 10 μL of Eu-cAMP tracer to the cell plate, followed by 10 μL of Ulight-anti-cAMP;

[0341] 2.9 Incubate at room temperature for 1 hour, then use an Envision 2105 plate reader to detect the wavelength values ​​at 665nm and 615nm.

[0342] 3. Data Analysis Methods

[0343] The data was calculated using the following formula and plotted as a curve. After fitting, the IC was calculated. 50 value:

[0344] 3.1 Z'factor=1-3*(SDMax+SDMin) / (MeanMax-MeanMin);

[0345] 3.2 CVMax=(SDMax / MeanMax)*100%;

[0346] 3.3 CVMin=(SDMin / MeanMin)*100%;

[0347] 3.4 S / B = Signal / Background;

[0348] 3.5 IC 50 Equation for calculating the value:

[0349] Y=Bottom+(Top-Bottom) / (1+10^((LogEC 50 -X)*HillSlope))

[0350] X: Logarithmic value of compound concentration; Y: Activity %

[0351] 4. Experimental Results

[0352] The peptides of this application have a clear in vitro cell-binding affinity for SSTR2. Some peptides of this application exhibit excellent antagonistic activity against the SSTR2 receptor. For example, peptides 4 and 6 of this application show in vitro activities comparable to or better than JR11 and LM3 (peptide 4, IC50, 100 mg / kg). 50 =10.92 nM; peptide 6, IC50 50 =22.98nM; JR11, IC 50 =21.24nM; LM3, IC 50 =12.81 nM), and the activity of the peptide is not affected after being conjugated with the chelating agent DOTA, and is even improved to a certain extent (e.g., DOTA-peptide 4, IC50 = 12.81 nM). 50=5.21 nM; DOTA-peptide 6, IC50 50 =8.74nM; DOTA-JR11, IC 50 =8.15nM; DOTA-LM3, IC 50 =5.45nM), activity is maintained after complexing with metals ( 139 La-DOTA-peptide 6, IC 50 =10.14nM).

[0353] Test c: In vitro SSTR1, SSTR3, SSTR4, and SSTR5 receptor agonist activity assays of the polypeptide conjugates of this application.

[0354] 1. Reagents and Consumables

[0355] 1.1 Cell lines: Flp-In-CHO-SSTR1 stable pool cells, Flp-In-CHO-SSTR3 stable pool cells, Flp-In-CHO-SSTR4 stable pool cells, and Flp-In-CHO-SSTR5 stable pool cells.

[0356] 1.2 Complete culture medium: Ham's F-12K + 10% FBS + 1x Penicillin-Streptomycin (PS) + 600 μg / ml Hygromycin B

[0357] 1.3 Cell seeding medium: Ham's F-12K + 10% FBS

[0358] 1.4 Detection buffer: 1X HBSS + 20mM HEPES + 0.1% BSA + 500μM IBMX

[0359] 1.5 The sources of reagents and consumables are shown in Table A.

[0360] 2. Experimental Methods

[0361] 2.1 The above four cell lines were cultured in complete culture medium at 37°C and 5% CO2, maintaining the cell density in a sub-confluence state.

[0362] 2.2 Cells were seeded at a rate of 7 K / 25 μL / well in 384-well plates (Perkin Elmer, 6007680) and cultured overnight at 37°C and 5% CO2.

[0363] 2.3 After the culture is complete, remove the cell culture plate, remove the culture medium, and quickly add 15 μL of detection buffer to the experimental detection wells;

[0364] 2.4 Prepare 8X of the analyte compound and 8X of forskolin (4 μM) using the detection buffer;

[0365] 2.5 Add 2.5 μL of the 8X test compound working solution to the cell culture plate and incubate at 37°C for 10 min;

[0366] 2.6 Add 2.5 μL of 8X forskolin working solution to the cell culture plate and incubate at 37°C for 30 min;

[0367] 2.7 Dilute Eu-cAMP tracer and Ulight-anti-cAMP with cAMP detection buffer;

[0368] 2.8 Add 10 μL of Eu-cAMP tracer to the cell plate, followed by 10 μL of Ulight-anti-cAMP;

[0369] 2.9 Incubate at room temperature for 1 hour, then use an Envision 2105 plate reader to detect the wavelength values ​​at 665nm and 615nm.

[0370] 3. Data Analysis Methods

[0371] The data was calculated using the following formula and plotted as a curve. After fitting, EC was calculated. 50 value:

[0372] 3.1 Z'factor=1-3*(SDMax+SDMin) / (MeanMax-MeanMin);

[0373] 3.2 CVMax=(SDMax / MeanMax)*100%;

[0374] 3.3 CVMin=(SDMin / MeanMin)*100%;

[0375] 3.4 S / B=Singal / Background;

[0376] 3.5 Calculation Equation for EC 50 Value:

[0377] Y=Bottom+(Top-Bottom) / (1+10^((LogEC 50 -X)*HillSlope))

[0378] X: log value of compound concentration; Y: Activity%.

[0379] 4. Experimental Results

[0380] Table 2

[0381] As shown in Table 2, the compound DOTA-peptide 1 in this application is consistent with DOTA-TATE, exhibiting high affinity for SSTR2, some affinity for SSTR4, and almost no affinity for SSTR1. However, compared to DOTA-TATE, the compound DOTA-peptide 1 in this application shows a significant difference in affinity for SSTR3 and SSTR5, indicating that DOTA-peptide 1 has better SSTR2 selectivity.

[0382] Experimental Example 2: 177 Preparation of Lu-labeled compounds

[0383] 177 Preparation of Lu-DOTA-peptide 1

[0384] The ligand DOTA-peptide 1 was dissolved in ultrapure water to a concentration of 1 mg / mL. 9.4 μL of this solution was added to 485 μL of 0.25 M sodium acetate buffer (pH = 5.0) containing ascorbic acid (concentration 15.8 mg / mL). Then, approximately 5 mCi was added. 177 LuCl3 (approximately 5 μL in 0.04 N HCl) was mixed thoroughly and then placed in a 95°C constant temperature mixer and heated with shaking for 30 min. After the reaction was complete, the following was obtained: 177 Lu-DOTA-peptide 1. Samples were sent for radio-HPLC analysis, and the results showed a labeling rate >99% and a radiochemical purity (radiochemical grade) of 97.57%. The labeled solution can be directly used for animal administration without further purification.

[0385] 177 Preparation of Lu-DOTA-TATE

[0386] The labeling was prepared using the same method as in the previous step. 177 Lu-DOTA-TATE (labeling rate >99%, radiochemical purity 98.25%). The labeled solution can be used directly for animal administration without purification.

[0387] 177 Lu-DOTA-peptide 4 177 Lu-DOTA-peptide 6 177 Lu-DOTA-JR11 177 Lu-DOTA-peptide 9 177 Lu-DOTA-peptide 12 177 Lu-DOTAGA-peptide 1 177Lu-DOTA-PEG2-peptide 1, 177 Preparation of Lu-DOTAGA-PEG2-peptide 1

[0388] Using the above 177 Lu-DOTA-peptide 1 was prepared using the same labeling method. 177 Lu-DOTA-peptide 4 (labeling rate >99%, radiochemical purity 95.11%) 177 Lu-DOTA-peptide 6 (labeling rate >99%, radiochemical purity 92.55%) 177 Lu-DOTA-JR11 (labeling rate >99%, radiochemical purity 92.48%) 177 Lu-DOTA-peptide 9 (labeling rate >99%, radiochemical purity 98.11%) 177 Lu-DOTA-peptide 12 (labeling rate >99%, radiochemical purity 98.86%) 177 Lu-DOTA-peptide 14 (labeling rate >99%, radiochemical purity 92.98%) 177 Lu-DOTAGA-peptide 1 (labeling rate >99%, radiochemical purity 98.35%) 177 Lu-DOTA-PEG2-peptide 1 (labeling rate >99%, radiochemical purity 96.69%) 177 Lu-DOTAGA-PEG2-peptide 1 (labeling rate >99%, radiochemical purity 96.17%). The labeling solution can be used directly for animal administration without purification.

[0389] Experimental Example 3: 177 Lu-SPECT / CT model mouse imaging experiment:

[0390] 1. Laboratory animals

[0391] 1.1 Species, strains and grades

[0392] B-NDG mouse NCI-H524 small cell lung cancer subcutaneous xenograft model (Biocytok (Beijing) Pharmaceutical Technology Co., Ltd.).

[0393] 2. Animal grouping

[0394] Select tumors with an average volume of 300-500 mm 3 The tumor-bearing mice were randomly divided into groups. 177 Lu-DOTA-peptide 4 177 Lu-DOTA-peptide 6 177 Lu-DOTA-JR11 were used as test samples.

[0395] 3. Experimental Design

[0396] 3.1 Dosage: 300 μCi / animal

[0397] 3.2 Administration method: Intravenous injection (iv) single dose

[0398] 3.3 Imaging time points: 4h, 24h, and 72h after drug administration

[0399] 3.4 Drug dilution and tail vein injection

[0400] According to the experimental design and sample concentration, the sample was diluted and dispensed using physiological saline with the aid of a Capintec CRC-55tR radionuclide activity meter and a 0.3 mL insulin syringe. The activity was approximately 300 μCi / 0.15 mL / vial (containing 0.5 nmol of the target peptide conjugate). The dispensing time was recorded. Each mouse was given a single tail vein injection according to the experimental design, and the injection time for each mouse was recorded. After injection, the syringes used were collected, the activity was measured, and the values ​​and response times were recorded.

[0401] 4. SPECT-CT image acquisition

[0402] SPECT-CT imaging was performed on animals under gas anesthesia using the MadicLab small animal trimodal imaging system from Shandong MadicLand Technology Co., Ltd. The imaging parameters were as follows: CT tube voltage was set to 70V, CT tube current to 600A, CT source center distance to 224mm, and CTFov diameter to 1-D80 in the animal chamber; SPECT scan was set to non-fixed angle acquisition for 1200s; and appropriate isotopes were selected based on the experimental drugs.

[0403] 5. Image Reconstruction

[0404] After the scan is complete, set the reconstruction parameters and then initiate reconstruction. CT reconstruction parameters: CTFOV diameter is 80mm, cutoff frequency is 0.40Hz, CT reconstruction accuracy is 200μm; SPECT reconstruction parameters: FOV diameter is 85mm, SPECT reconstruction accuracy is 1.0, number of iterations is 10, and calibration coefficient is 1. Export the SPECT-CT image fusion.

[0405] 6. Image viewing and analysis

[0406] The fused SPECT-CT images were analyzed and delineated using the image processing and analysis software PMOD.

[0407] 7. Experimental Results

[0408] In this application 177Lu-labeled targeting peptide conjugates showed significant and prolonged tumor uptake in a mouse model of NCI-H524 small cell lung cancer subcutaneous xenografts, while non-target organs showed only minimal or no uptake. For example... 177 Lu-DOTA-JR11 177 Lu-DOTA-peptide 4 177 Figures 1-3 show the SPECT-CT images of Lu-DOTA-peptide 6 in a mouse model of NCI-H524 small cell lung cancer subcutaneous xenograft tumors. The images show that the compound of this invention is significantly and persistently uptaken by the tumor, with only small amounts taken up in non-target organs such as the kidneys, stomach, small intestine, and large intestine. The images were analyzed and delineated; the image delineation is shown in Figure 3A. Based on the results in Figures 1-3, Figure 3A, and Table 3, it can be seen that the invention… 177 Lu-DOTA-peptide 4 (tumor AUC = 290.3) and 177 Lu-DOTA-peptide 6 (tumor AUC = 267) tumor uptake is higher than existing... 177 Lu-DOTA-JR11 (tumor AUC = 253.8), 177 Lu-DOTA-TATE (tumor AUC = 60.1) was high, and 177 Lu-DOTA-peptide 6 has lower non-target organ uptake and a higher tumor / non-target organ ratio, especially the tumor / kidney ratio, which suggests that it may have lower nephrotoxicity at the same dose.

[0409] Similarly, 177 Lu-DOTA-peptide 9 177 Lu-DOTAGA-peptide 1 177 Lu-DOTA-PEG2-peptide 1, 177 Lu-DOTAGA-PEG2-peptide 1, 177 Using the same experimental model mice and methods, Lu-DOTA-TATE was administered at a dose of 300 μCi. Imaging was performed at 2h, 4h, and 24h after administration, and SPECT-CT image acquisition and reconstruction were performed using the same methods. The results still showed that the targeted peptide conjugate of this application had high tumor uptake and low uptake in non-target organs. For example... 177 Lu-DOTA-peptide 9 (tumor / stomach = 8.7, tumor / small intestine = 13.6, tumor / large intestine = 26.4), 177 Lu-DOTAGA-peptide 1 (tumor / kidney = 4.9, tumor / stomach = 7.8, tumor / colon = 14.8), 177 Lu-DOTA-PEG2-peptide 1 (tumor / kidney = 5.1, tumor / stomach = 8.3, tumor / colon = 17.6), 177Lu-DOTAGA-PEG2-peptide 1 (tumor / stomach = 11, tumor / colon = 18.6), relative to 177 Lu-DOTA-TATE (tumor / kidney = 4.1, tumor / stomach = 5.4, tumor / colon = 12.6) has lower uptake in non-target organs and a higher tumor / non-target organ ratio, especially the tumor / kidney, tumor / colon, and tumor / stomach ratios, which indicate that at the same dose, it may have lower toxicity to the colon, stomach, and kidney.

[0410] In summary, the targeted peptide conjugates of this application exhibit high tumor specificity and low uptake in non-target organs, which implies potentially better therapeutic efficacy and higher safety.

[0411] Table 3

[0412] Experiment Example 4: 177 In vivo biodistribution of Lu-labeled compounds

[0413] Experiment a. Biodistribution experiment of NCI-H524:

[0414] 1. Laboratory animals

[0415] 1.1 Species, strains and grades

[0416] B-NDG mouse NCI-H524 small cell lung cancer subcutaneous xenograft model (Biocytogen (Beijing) Pharmaceutical Technology Co., Ltd.)

[0417] 2. Animal grouping

[0418] Using a randomized controlled trial design, 30 B-NDG mice with NCI-H524 tumor models were divided into two groups based on their body weight. 177 Lu-DOTA-TATE group and 177 Lu-DOTA-peptide group 1), each group is further divided into 4 subgroups (group 1-group 4, 2h, 4h, 24h and 72h).

[0419] 3. Experimental Design

[0420] 3.1 Dosage: 100 μCi / animal. According to the experimental design and labeling solution concentration, the labeling solution was diluted and dispensed with physiological saline with the assistance of a Capintec CRC-55tR radionuclide activity meter and a 0.3 mL insulin syringe. The activity was approximately 100 μCi / vial.

[0421] 3.2 Administration method: Intravenous injection (iv) single dose

[0422] 3.3 Sampling time points: 2h, 4h, 24h, and 72h after drug administration, with 3 animals at each time point.

[0423] Organs and tissues: At various time points in the animal series, the eyeballs were gouged out and blood was expelled (blood samples were retained). The heart, liver, spleen, lungs, kidneys, adrenal glands, stomach, femur (hind limb), muscles, small intestine, large intestine (with contents removed), pancreas, and tumors were harvested. Biological samples were collected at each time point. Organs and tissues were gently squeezed, and residual blood was absorbed with absorbent paper. The weight was weighed and recorded. Samples were placed in EP tubes and subjected to gamma-counter testing. Results were expressed as CPM (CPM: counts of radioactivity per minute).

[0424] 3.4 Data Analysis Methods

[0425] %ID / g=Atissue / [(A0-Aresidue)*Mtissue]×100%

[0426] A0: Total radioactivity count (CPM) of the syringe before drug administration.

[0427] Aresidue: Residual radioactivity count in the syringe after drug administration (CPM)

[0428] Atissue: Organ Radioactivity Count (CPM)

[0429] Mtissue: Detects tissue sample weight (g)

[0430] Physical attenuation correction: 177 Lu physical decay: Activity dose at time T = 0.5^(T / 160.8)

[0431] Multiplying the administered dose (A0 - Aresidue) by the decay factor over the corresponding time period gives the corrected CPM value. Calculate %ID / g.

[0432] 4. Experimental Results

[0433] 177 Lu-DOTA-TATE and 177 The in vivo biodistribution of Lu-DOTA-peptide 1 in a mouse model of NCI-H524 small cell lung cancer subcutaneous xenograft is shown in Figures 4 and 5, and the specific distribution data are shown in Tables 4 and 5. Based on the results in the tables, it can be seen that the present application… 177 Lu-DOTA-peptide 1 showed better biodistribution in model mice, with high tumor specificity, except for the kidneys (because this radionuclide-conjugated drug is metabolized and excreted by the kidneys, and part of it is reabsorbed by the kidneys, but compared to...). 177 Besides the kidneys, which absorb even less of Lu-DOTA-TATE, other normal organs and tissues absorb almost nothing. 177 Lu-DOTA-TATE is absorbed to some extent in organs such as the lungs, adrenal glands, stomach, and pancreas, compared to... 177Lu-DOTA-peptide 1 is significantly absorbed by these organs.

[0434] Table 4: 177 Lu-DOTA-TATE model mouse biodistribution

[0435] Table 5: 177 Biodistribution of Lu-DOTA-peptide 1 in model mice

[0436] Experiment b. Biodistribution experiment of NCI-H69:

[0437] 1. Laboratory animals

[0438] 1.1 Species, strains and grades

[0439] M-NSG mouse NCI-H69 small cell lung cancer subcutaneous xenograft model (Biocytogen (Beijing) Pharmaceutical Technology Co., Ltd.)

[0440] 2. Animal grouping

[0441] The mice were randomly assigned to groups based on their body weight. The M-NSG mouse NCI-H69 tumor model was divided into groups according to the number of test samples, with 9 mice in each group and 3 mice in each group as blank controls. Then, within each group, the mice were further divided into 3 subgroups (groups 1-3, 4h, 24h, and 72h) according to different time points after drug administration.

[0442] 3. Experimental Design

[0443] 3.1 Dosage of test sample: 100 μCi / animal. According to the experimental design and the concentration of the labeling solution, the labeling solution was diluted and dispensed with physiological saline with the assistance of a Capintec CRC-55tR radionuclide activity meter and a 0.3 mL insulin injection. The activity was approximately 100 μCi / vial, and the molar number of the target peptide conjugate contained therein was 0.5 nmol.

[0444] 3.2 Administration method: Intravenous injection (iv) single dose

[0445] 3.3 Sampling time points: 4h, 24h, and 72h after drug administration, with 3 animals sampled at each time point.

[0446] Organs and tissues: At various time points in the animal series, the eyeballs were gouged out and blood was expelled (blood samples were retained). The heart, liver, spleen, lungs, kidneys, adrenal glands, stomach, femur (hind limb), muscles, small intestine, large intestine (with contents removed), pancreas, and tumors were harvested. Biological samples were collected at each time point. Organs and tissues were gently squeezed, and residual blood was absorbed with absorbent paper. The weight was weighed and recorded. Samples were placed in EP tubes and subjected to gamma-counter testing. Results were expressed as CPM (CPM: counts of radioactivity per minute).

[0447] 3.4 Data analysis methods are the same as in Experiment a

[0448] 4. Experimental Results

[0449] 177 Lu-DOTA-JR11 and 177 Lu-DOTA-peptide 4 177 The in vivo biodistribution of Lu-DOTA-peptide 6 in a mouse model of NCI-H69 small cell lung cancer subcutaneous xenograft tumors is shown in Figures 6, 7, and 8. Specific distribution data are shown in Tables 6, 7, and 8. The results of calculating the tumor AUC from 4 h to 72 h and the tumor-to-important non-target organ AUC ratio are shown in Table 9. Based on the results in the tables, it can be seen that the present application… 177 Lu-DOTA-peptide 4 and 177 Lu-DOTA-peptide 6 exhibited better biodistribution in a mouse model of H69 small cell lung cancer subcutaneous xenograft tumors. Even with low SSTR2 expression in the H69 cell line (Ref.: Mol. Cancer Ther. 2023, 22(12), 1434-1443), the tumor uptake of the compound of this invention remained high, and compared to 177 Lu-DOTA-JR11, 177 Lu-DOTA-peptide 4 and 177 Lu-DOTA-peptide 6 had a higher tumor AUC, indicating that... 177 Lu-DOTA-peptide 4 and 177 Lu-DOTA-peptide 6 has better efficacy in tumor treatment.

[0450] Table 6: 177 Biological distribution of Lu-DOTA-JR11 model mice

[0451] Table 7: 177 Biodistribution of Lu-DOTA-peptide 4 in model mice

[0452] Table 8: 177 Biodistribution of Lu-DOTA-peptide 6 in model mice

[0453] Table 9: AUC Calculation

[0454] Experimental Example 5: 177 Antitumor efficacy experiments of Lu-labeled compounds

[0455] 1. Laboratory animals

[0456] 1.1 Species, strains and grades

[0457] B-NDG mouse NCI-H524 small cell lung cancer subcutaneous xenograft model (Biocytogen (Beijing) Pharmaceutical Technology Co., Ltd.)

[0458] NKG mouse NCI-H69 small cell lung cancer subcutaneous xenograft model (Cyagen Biosciences Co., Ltd.)

[0459] 2. Animal grouping

[0460] The grouping was carried out using a randomized area design, and the animals were grouped according to their body weight and tumor volume. Twenty-four NDG mice NCI-H524 or 24 NKG mice NCI-H69 tumor models were divided into four groups (Vehicle, low-dose group, medium-dose group, and high-dose group), with six animals in each group.

[0461] 3. Experimental Design

[0462] 3.1 Dosage: 0.5 mCi / animal, 0.8 mCi / animal and 1 mCi / animal

[0463] 3.2 Administration method: Intravenous injection (iv) single dose

[0464] 3.3 Mouse body weight measurement and experimental indicators:

[0465] Tumor volume was measured twice weekly using calipers, and mouse body weight was measured using an electronic balance. The major and minor diameters of the tumor were measured, and the volume was calculated using the formula: Volume = 0.5 × Major diameter × Minor diameter². The T / C value was calculated based on the tumor volume, where T is the average relative tumor volume (RTV) of each treatment group, and C is the average relative tumor volume (RTV) of the control group. RTV is the ratio of tumor volume after administration to tumor volume before administration. Tumor growth inhibition rate (TGITV%) = (1 - T / C) × 100%.

[0466] At the end of the experiment, the animals were euthanized, the tumors were removed, weighed, and neatly arranged for photographs.

[0467] 3.4 Statistical Analysis of Data

[0468] The mean and standard deviation of each group were calculated using statistical software, and normality and homogeneity of variance tests were performed. If P ≥ 0.05, one-way ANOVA was performed. If the normality and / or homogeneity of variance tests were not met (P < 0.05), a nonparametric Kruskal-Wallis test was performed. Intergroup statistical analysis was performed on tumor volume, with a significance criterion of P < 0.05.

[0469] 4. Experimental Results

[0470] 4.1 Responses and weight changes in experimental animals after drug administration

[0471] During the treatment, the tumor-bearing mice in each group responded to the application of this invention. 177 All Lu-labeled compounds showed good tolerability; mice maintained stable weight, normal food and water intake, and were in good general condition with no obvious abnormalities, and no withdrawal of treatment or death occurred; even at high doses, they still showed high safety.

[0472] 4.2 Tumor growth inhibition results

[0473] This application 177 The Lu-labeled compound exhibited significant tumor-suppressive effects in both the B-NDG mouse NCI-H524 small cell lung cancer subcutaneous xenograft model and the NKG mouse NCI-H69 small cell lung cancer subcutaneous xenograft model, and its tumor-inhibiting effect was dose-dependent. This application 177 Lu-labeled compounds, exemplarily, for example 177 Lu-DOTA-peptide 1 caused tumor regression or complete regression in some groups and had a higher TGI index.

[0474] Experimental Example 6: 68 Preparation of Ga-labeled compounds

[0475] 68 Preparation of Ga-NODAGA-JR11

[0476] Using 6 mL of sterile ultrapure 0.6 M hydrochloric acid solution at a flow rate of 2 mL / min... 68 Ge / 68 The Ga generator was used for elution, and the eluent with the highest intermediate activity concentration (approximately 5 mCi / mL) was collected. Approximately 5 mCi of this nuclide solution was taken and added to 250 μL of 1M sodium acetate buffer (pH = 4.0-4.5), followed by the sequential addition of 35 μL of 12M sodium hydroxide solution and an aqueous solution of NODAGA-JR11 (6.2 nmol). The mixture was then heated and stirred in a 37°C heated-lid mixer for 30 min. After the reaction was complete, the following was obtained: 68Ga-NODAGA-JR11. Samples were sent for radio-HPLC analysis, and the results showed a labeling rate >99% and a radiochemical purity of 94.06%. The labeled solution can be used directly for animal administration without further purification.

[0477] 68 Preparation of Ga-NODAGA-peptide 6

[0478] Using 6 mL of sterile ultrapure 0.6 M hydrochloric acid solution at a flow rate of 2 mL / min... 68 Ge / 68 The Ga generator was used for elution, and the eluent with the highest intermediate activity concentration (approximately 5 mCi / mL) was collected. Approximately 5 mCi of this nuclide solution was added to 250 μL of 3M sodium acetate solution, followed by the addition of an aqueous solution of NODAGA-peptide 6 (6.2 nmol). The mixture was then heated and stirred in a 95°C heated-lid mixer for 15 min. After the reaction was complete, the desired result was obtained. 68 Ga-NODAGA-peptide 6 was sampled and sent for radio-HPLC analysis, which showed a radiochemical purity of 93.64%. The C18 purification column was activated three times with 0.3M sodium acetate solution (pH = 4.0-4.5) and then emptied. The labeled solution was transferred to the purification column, and the C18 column was first rinsed with purified water, then washed with 100 μL of 0.3M sodium acetate solution containing 30% ethanol (pH = 4.0-4.5) and emptied to obtain the purified sample. This sample was directly used in animal experiments, and the radiochemical purity was 95.26% as determined by radio-HPLC.

[0479] Experiment Example 7: 68 PET / CT imaging experiments with Ga-labeled compounds:

[0480] Experiment a. PET / CT imaging experiment in NCI-H69 cell CDX model: 1. Experimental animals 1.1 Species, strains and grades

[0481] NSG mouse NCI-H69 small cell lung cancer subcutaneous xenograft model (Biocytok (Beijing) Pharmaceutical Technology Co., Ltd.).

[0482] 2. Experimental Procedure

[0483] Select tumors with a mean volume of 300 mm 3 Approximately 20 tumor-bearing mice were randomly divided into two groups based on their body weight. 68Ga-labeled compounds were assigned to one group, administered intravenously (iv), with a single dose of 0.2 mCi per animal. According to the experimental design and labeling solution concentration, the labeling solution was diluted and dispensed using physiological saline with the aid of a Capintec CRC-55tR radionuclide activity meter and a 0.3 mL insulin syringe, resulting in an activity of approximately 200 μCi per syringe. Following administration, PET-CT scans were performed at different time points using the MadicLab small animal trimodal imaging system from Shandong MadicLab Technology Co., Ltd. Imaging parameters were as follows: CT tube voltage set to 70V, CT tube current set to 600ACT, source center distance set to 281 mm, CTFov diameter set to animal chamber 1-D80, and PET scan set to non-fixed angle acquisition for 7200 s. The appropriate isotope was selected based on the experimental drug. After scanning, reconstruction parameters were set, and reconstruction was initiated. CT reconstruction parameters: CT FOV diameter 80mm, cutoff frequency 0.40Hz, CT reconstruction accuracy 200μm; PET reconstruction parameters: FOV diameter 81mm, PET reconstruction accuracy 1.457, iteration count 10, calibration coefficient. The reconstructed PET and CT images are fused to generate a PET / CT fused image. On the PET / CT fused image, the region of interest (VOI) is manually delineated, including the target region (tumor tissue) and non-target organs such as the heart (representing the blood pool), liver, spleen, lungs, kidneys, and gastrointestinal tract. The maximum and average normalized uptake values ​​(SUVs) are calculated and obtained. max and SUV mean ).

[0484] 3. Experimental Results

[0485] 68 Ga-NODAGA-JR11 and 68 Figures 9 and 10 show the PET / CT fusion images of Ga-NODAGA-peptide 6 in a human small cell lung cancer NCI-H69 cell CDX model and the time-activity curve of tumor delineation, respectively. The experimental results show that... 68 Ga-NODAGA-peptide 6 exhibits excellent pharmacokinetic characteristics in vivo. Following tail vein injection, the drug rapidly distributes through blood circulation, with significant uptake observed at the target tumor site within 1 minute. Tumor enrichment continues to increase, reaching peak uptake at 110-120 minutes and remaining there for an extended period. At this time, the tumor region exhibits significantly enhanced radioactive signals (hot zones), SUV max It is 2.26, SUV mean A value of 1.09 indicates that it has high affinity and rapid binding ability to the target. Regarding excretion, 68Ga-NODAGA-peptide 6 is primarily excreted via the renal route, and both kidneys and bladder showed clear imaging after injection. Enrichment in non-target organs was generally low, except for higher uptake in the kidneys due to its status as the primary excretion route. Radioactivity was rapidly cleared from the blood pool, and the heart showed weak imaging signal 15 minutes after injection. Only small amounts of uptake were observed in the liver, spleen, lungs, and gastrointestinal tract, with signal intensities far lower than those in tumors. These results indicate... 68 Ga-NODAGA-peptide 6 exhibited rapid tumor targeting, high tumor uptake, and clear kinetics primarily via renal excretion in the NCI-H69 tumor model. 68 Compared with Ga-NODAGA-JR11, 68 Ga-NODAGA-peptide 6 at peak tumor uptake SUV max (2.26 vs 1.63) and SUV mean The value of (1.09 vs 0.81) is higher. Furthermore, 68 Ga-NODAGA-JR11 achieves faster tumor clearance, with peak uptake at the tumor site occurring 10-12 minutes after injection, followed by clearance. The tumor SUV value reaches a certain level 120 minutes post-injection. mean Only 0.66.

[0486] Experiment b. PET / CT imaging experiment in NCI-H524 cell CDX model

[0487] 1. Laboratory animals

[0488] 1.1 Species, strains and grades

[0489] NSG mouse NCI-H524 small cell lung cancer subcutaneous xenograft model (Biocytok (Beijing) Pharmaceutical Technology Co., Ltd.).

[0490] 2. Experimental Procedure

[0491] Select tumors with a mean volume of 300 mm 3 Approximately 20 tumor-bearing mice were randomly divided into two groups based on their body weight. 68Ga-labeled compounds were assigned to one group, administered intravenously (iv) at a dose of 0.2 mCi. According to the experimental design and labeling solution concentration, the labeling solution was diluted and dispensed using physiological saline with the aid of a Capintec CRC-55tR radionuclide activity meter and a 0.3 mL insulin syringe, resulting in an activity of approximately 200 μCi / vial. Following administration, PET-CT scans were performed at different time points using the MadicLab small animal trimodal imaging system from Shandong MadicLab Technology Co., Ltd. Imaging parameters were as follows: CT tube voltage set to 70V, CT tube current to 600ACT, source center distance to 281 mm, CTFov diameter to animal chamber 1-D80, and PET scan set to non-fixed angle acquisition for 7200 s. The appropriate isotope was selected based on the experimental drug. After scanning, reconstruction parameters were set, and reconstruction was initiated. CT reconstruction parameters: CT FOV diameter 80mm, cutoff frequency 0.40Hz, CT reconstruction accuracy 200μm; PET reconstruction parameters: FOV diameter 81mm, PET reconstruction accuracy 1.457, iteration count 10, calibration coefficient. The reconstructed PET and CT images are fused to generate a PET / CT fused image. On the PET / CT fused image, the region of interest (VOI) is manually delineated, including the target region (tumor tissue) and non-target organs such as the heart (representing the blood pool), liver, spleen, lungs, kidneys, and gastrointestinal tract. The maximum and average normalized uptake values ​​(SUVs) are calculated and obtained. max and SUV mean ).

[0492] 3. Experimental Results

[0493] 68 Ga-NODAGA-JR11 and 68 Figures 11 and 12 show the PET / CT fusion images and time-activity curves of tumor delineation in a human small cell lung cancer NCI-H524 cell CDX model of Ga-NODAGA-peptide 6. The experimental results show that... 68 Ga-NODAGA-peptide 6 injection exhibits excellent pharmacokinetic characteristics in vivo. Following tail vein injection, the drug rapidly distributes through blood circulation, with significant uptake observed at the target tumor site within 1 minute. Tumor enrichment continues to increase, reaching peak uptake at 110-120 minutes and remaining there for an extended period. At this time, the tumor region exhibits significantly enhanced radioactive signals (hot zones), SUV max It costs 6.29 for SUVs. mean The value was 2.71, indicating high affinity and rapid binding to the target. Regarding excretion... 68Ga-NODAGA-peptide 6 is primarily excreted via the renal route, and both kidneys and bladder showed clear imaging after injection. Enrichment in non-target organs was generally low, except for higher uptake in the kidneys due to its status as the primary excretion route. Radioactive clearance from the blood pool was rapid, and the heart showed weak imaging signal 30 minutes after injection. Only small amounts of uptake were observed in the liver, spleen, lungs, and gastrointestinal tract, with signal intensities far lower than those in tumors. These results indicate... 68 Ga-NODAGA-peptide 6 exhibited rapid tumor targeting, high tumor uptake, and clear kinetics primarily via renal excretion in the NCI-H524 tumor model. 68 Compared with Ga-NODAGA-JR11, 68 Ga-NODAGA-peptide 6 at peak tumor uptake SUV max (6.29 vs 5.41) and SUV mean (2.71 vs 2.08) is a higher value. 68 The tumor clearance trend of Ga-NODAGA-JR11 in the NCI-H524 model and 68 Similar to Ga-NODAGA-peptide 6, the uptake at the tumor site reached its peak 110-120 minutes after drug injection, and no clearance was observed, indicating a long period of signal concentration in the tumor.

[0494] Experimental Example 8: 225 Preparation of Ac-labeled compounds

[0495] Take a 0.5 mL reaction tube, add a 0.25 M sodium acetate solution (pH = 6.00-6.05) containing 10 mg / mL sodium vitamin C, then add sequentially an aqueous solution (5 mg / mL, 10 nmol) of ligands (DOTA-peptide 1 to DOTA-peptide 6, DOTA-JR11) and 20 μCi of nuclide. 225 Mix Ac (2 μCi / μLin 0.04M hydrochloric acid) thoroughly, and place the reaction tube on a constant temperature mixer at 90℃ and 300 rpm for 40 min. After the reaction, take a small amount of the reaction solution for radio-TLC detection: using Agilent iTLC-SG (1.5×10cm) chromatographic paper as the carrier and 0.5M sodium citrate buffer (pH=5.0±0.02) as the developing solvent, spot 0.1 μCi to 1.5 cm from the edge of the chromatographic paper. After development with the developing solvent, air dry, then cut the chromatographic paper into two sections from the middle, and let stand for >6 hours before proceeding. 213 Bi-channel detection. Free molecules are counted by counting the upper portion after the chromatographic paper is cut open. 225Ac content, calculated as the lower segment of chromatographic paper, showed a radiochemical purity >95%. Approximately 1 μCi of the reaction solution was then subjected to radio-HPLC analysis: 5 mM ammonium acetate solution (pH adjusted to 4.5 with trifluoroacetic acid) was used as mobile phase A, and 0.1% trifluoroacetic acid-acetonitrile was used as mobile phase B. The fraction was collected using a fraction collector at 1.5 min / tube, and allowed to stand for >6 h before analysis. 213 Bi-channel detection showed that the radiochemical purity of the principal components was >90%.

[0496] Experiment Example 9: 225 Pharmacodynamic experiments of Ac-labeled compounds in model mice

[0497] Experiment a. Study on the efficacy of NCI-H69 cell CDX model mice

[0498] 1. Laboratory animals

[0499] Subcutaneous xenograft model of NCI-H69 small cell lung cancer in female NSG mice (Biocytok (Beijing) Pharmaceutical Technology Co., Ltd.).

[0500] 2. Animal grouping

[0501] Select tumors with an average volume of 100-200 mm 3 Approximately 5 tumor-bearing mice were randomly divided into 4 groups based on their body weight, for a total of 5 groups: Vehicle (saline), 225 Ac-DOTA-JR11 low-dose group (0.5 μCi / 0.5 nmol / animal), 225 Ac-DOTA-JR11 high-dose group (0.8 μCi / 0.5 nmol / animal), 225 Ac-DOTA-peptide 6 low-dose group (0.5 μCi / 0.5 nmol / animal) and 225 Ac-DOTA-peptide 6 high-dose group (0.8 μCi / 0.5 nmol / animal),

[0502] 3. Experimental Design

[0503] 3.1 Administration route: Intravenous injection (iv), single dose.

[0504] 3.2 Experimental Protocol: Day 0 was recorded as the day the animals were given the first dose of medication. Tumor volume and body weight were measured weekly after administration. Tumor volume in a single animal reached 3000 mm². 3 Euthanasia was performed, and the survival status of each group was recorded. The experimental observation indicators are as follows:

[0505] (1) Weighing and behavioral observation: Animals were weighed twice a week before and after administration (BW), and the relationship between changes in body weight and administration time was recorded. Simultaneously, the survival and health status of the mice were observed, including general conditions such as activity and feeding during administration. Body weight change (%) = (BW) / (BW) t -BW0) / BW0×100, where BW0 is the body weight at the start of drug administration, BW t Weight measured for each cycle.

[0506] (2) Tumor volume: Tumor volume (TV) was measured twice a week before and after drug administration to record the relationship between tumor growth and drug administration time. Tumor growth inhibition rate (TGI,%) = [1 - RTV(experimental group) / RTV(control group)] * 100%, where relative tumor volume (RTV) = TV t / TV0. TV t TV0: The tumor volume measured over one experimental cycle.

[0507] 3.3 Statistical Analysis of Data

[0508] The mean and standard deviation of each group were calculated using statistical software, and normality and homogeneity of variance tests were performed. If P ≥ 0.05, one-way ANOVA was performed. If the normality and / or homogeneity of variance tests were not met (P < 0.05), a nonparametric Kruskal-Wallis test was performed. Intergroup statistical analysis was performed on tumor volume, with a significance criterion of P < 0.05.

[0509] 4. Experimental Results

[0510] 4.1 Responses and weight changes in experimental animals after drug administration

[0511] During the experiment, each group of tumor-bearing mice exhibited the effects of this application. 225 All Ac-labeled compounds showed good tolerability; mice ate and drank normally, were in good general condition, and no obvious abnormal behavior or adverse reactions were observed. Only... 225 In the low-dose Ac-DOTA-JR11 group, one animal died on day 32 after administration. Overall, this death was likely related to the animal's low body weight rather than treatment-related factors. The body weight changes of animals in each group after administration are shown in Figure 13. In the high-dose group, animals experienced varying degrees of weight loss after administration, but subsequently recovered gradually, especially... 225 Animals in the high-dose Ac-DOTA-peptide 6 group experienced a weight loss of only about 5% at the experimental endpoint (day 59).

[0512] 4.2 Tumor growth inhibition results

[0513] Figure 14 shows the tumor growth inhibition in each group after drug administration. On day 26 after drug administration, the average tumor volume in the Vehicle group reached 2752.96 mm. 3 All treatment groups showed significant antitumor activity (p < 0.0001, One-way ANOVA with Dunnett's multiple comparisons test). 225 The mean tumor volume in the low-dose and high-dose groups of Ac-DOTA-JR11 was 744.99 mm. 3 and 76.11mm 3 The TGI values ​​were 80% and 97%, respectively, and the tumor regression rates were 0 / 4 and 4 / 4. 225 The mean tumor volume in the low-dose and high-dose groups of Ac-DOTA-peptide 6 was 199.64 mm. 3 and 67.43mm 3 The TGI values ​​were 92% and 97%, respectively, and the tumor regression rates were 1 / 4 and 4 / 4, respectively. This indicates that at high doses, the compounds of this application... 225 Ac-DOTA-peptide 6 antitumor effect and 225 It is comparable to Ac-DOTA-JR11, but at low doses, 225 Ac-DOTA-peptide 6 exhibited better tumor-suppressing effects.

[0514] 4.3 Survival Analysis

[0515] The survival curves of each group after drug administration are shown in Figure 15. The survival analysis results showed that during the 94-day experiment, animal mortality was mainly related to tumor progression (when the tumor size reached 3000 mm). 3 Euthanasia was performed at the time of treatment, and no treatment-related deaths were observed. The median survival in the Vehicle group was 30.5 days. 225 The low-dose Ac-DOTA-JR11 group lasted for 44 days. 225 The median survival in the high-dose Ac-DOTA-JR11 group was 78.5 days. 225 The median survival in the low-dose Ac-DOTA-peptide 6 group was 58 days. 225 Ac-DOTA-peptide 6 high-dose group for 76.5 days, compared with 225 The high-dose group of Ac-DOTA-JR11 is comparable. In summary, at low doses, the compounds of this application are comparable. 225 Ac-DOTA-peptide 6 extended survival by 27.5 days compared to the Vehicle group, while 225 Ac-DOTA-JR11 extended survival by only 13.5 days compared to the Vehicle group. Combined with the aforementioned tumor growth inhibition, this indicates that the compound in this application... 225Ac-DOTA-peptide 6 has better anti-tumor effects.

[0516] Experiment b. Study on the efficacy of NCI-H524 cell CDX model mice

[0517] 1. Laboratory animals

[0518] Subcutaneous xenograft model of small cell lung cancer NCI-H524 cells in female NSG mice (Biocytogen (Beijing) Pharmaceutical Technology Co., Ltd.).

[0519] 2. Animal grouping

[0520] Select tumors with a volume of 100-200 mm 3 Approximately 10 tumor-bearing mice were randomly divided into 3 groups of 4 mice each, based on their body weight: Vehicle (saline solution), 225 Ac-DOTA-JR11 high-dose group (0.5 μCi / 0.5 nmol / animal), 225 Ac-DOTA-peptide 6 high-dose group (0.5 μCi / 0.5 nmol / animal),

[0521] 3. Experimental Design

[0522] 3.1 Administration route: Intravenous injection (iv), single dose.

[0523] 3.2 Experimental Protocol: Day 0 was recorded as the day the animals were given the first dose of medication. Tumor volume and body weight were measured weekly after administration. Tumor volume in a single animal reached 3000 mm². 3 Euthanasia was performed, and the survival status of each group was recorded. The experimental observation indicators are as follows:

[0524] (1) Weighing and behavioral observation: Animals were weighed twice a week before and after administration (BW), and the relationship between changes in body weight and administration time was recorded. Simultaneously, the survival and health status of the mice were observed, including general conditions such as activity and feeding during administration. Body weight change (%) = (BW) / (BW) t -BW0) / BW0×100, where BW0 is the body weight at the start of drug administration, BW t Weight measured for each cycle.

[0525] (2) Tumor volume: Tumor volume (TV) was measured twice a week before and after drug administration to record the relationship between tumor growth and drug administration time. Tumor growth inhibition rate (TGI,%) = [1 - RTV(experimental group) / RTV(control group)] * 100%, where relative tumor volume (RTV) = TV t / TV0. TV t TV0: The tumor volume measured over one experimental cycle.

[0526] 3.3 Statistical Analysis of Data

[0527] The mean and standard deviation of each group were calculated using statistical software, and normality and homogeneity of variance tests were performed. If P ≥ 0.05, one-way ANOVA was performed. If the normality and / or homogeneity of variance tests were not met (P < 0.05), a nonparametric Kruskal-Wallis test was performed. Intergroup statistical analysis was performed on tumor volume, with a significance criterion of P < 0.05.

[0528] 4. Experimental Results

[0529] 4.1 Responses and weight changes in experimental animals after drug administration

[0530] During the experiment, each group of tumor-bearing mice exhibited the effects of this application. 225 All Ac-labeled compounds showed good tolerability; mice ate and drank normally, were in good general condition, and no obvious abnormal behavior or adverse reactions were observed, nor were any treatment-related deaths. The changes in body weight of the animals in each group after administration are shown in Figure 16. 225 Ac-DOTA-JR11 and 225 All animals in the Ac-DOTA-peptide group 6 experienced varying degrees of weight loss, but subsequently recovered gradually. 225 Ac-DOTA-peptide 6 resulted in a weight loss of no more than 5% at the observation endpoint (day 63).

[0531] 4.2 Tumor growth inhibition results

[0532] Figure 17 shows the tumor growth inhibition in each group after drug administration. On day 26 after drug administration, the average tumor volume in the Vehicle group reached 2278.07 mm. 3 All treatment groups showed significant antitumor activity (p < 0.0001, One-way ANOVA with Dunnett's multiple comparisons test). 225 The average tumor volume in the Ac-DOTA-JR11 group of animals was 104.29 mm. 3 The TGI was 96%, and the tumor regression rate was 3 / 4 (FIG.4). 225 The average tumor volume in the Ac-DOTA-peptide group 6 animals was 83.55 mm. 3 The TGI was 96%, and the tumor regression rate was 4 / 4. After 30 days of administration, the tumors in the treated group gradually grew, but compared to... 225 Ac-DOTA-JR11 group 225 Tumor growth was slower in the Ac-DOTA-peptide 6 group of animals.

[0533] 4.3 Survival Analysis

[0534] The survival curves of each group after drug administration are shown in Figure 18. The survival analysis results showed that during the 87-day experimental period, the main cause of death in the animals was tumor growth (tumor size reaching 3000 mm). 3 (Euthanasia was performed), and no treatment-related deaths were found. The median survival for the vehicle was 29 days. 225 The median survival in the Ac-DOTA-JR11 group was 50.5 days, and the overall survival was 63 days. 225 The median survival of the Ac-DOTA-peptide group 6 was 70 days, and the overall survival was 87 days.

[0535] In summary, 225 Ac-DOTA-peptide 6 showed significant tumor-suppressive activity and prolonged survival in NCI-H69 and NCI-H524 human small cell lung cancer CDX models, exhibiting superior antitumor activity compared to other drugs. 225 Ac-DOTA-JR11 was found to have no significant treatment-related toxicity in animal models, and the drug showed good safety and tolerability.

[0536] Those skilled in the art will recognize that the above embodiments and experimental examples are exemplary instances that specifically illustrate this application and are not intended to limit the scope of protection of this application. Any modifications, substitutions, alterations, equivalent structural or procedural transformations, recombinations, or direct or indirect applications in other related technical fields made using the principles and contents of this application are similarly included within the scope of protection of this application.

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