Tumor-targeting peptides against carcinoembryonic antigen-related cell adhesion molecule CEACAM6 and their applications

Abstract

The present invention discloses a tumor-targeting peptide against carcinoembryonic antigen-related cell adhesion molecule CEACAM6 and its application. The present invention provides a class of tumor-targeting peptides against carcinoembryonic antigen-related cell adhesion molecule (CEACAM6). These polypeptides can specifically target the tumor CEACAM6 receptor. At the same time, after coupling with a fluorescent dye, they can be used for optical imaging to accurately locate the tumor boundary for doctors during the operation, guide the resection of the lesion, help improve the thoroughness of the operation, and thus improve the prognosis. In addition, this class of targeting polypeptides can also be coupled with radionuclides for radionuclide imaging to achieve the purpose of early diagnosis and treatment of tumors.

Description

Technical Field

[0001] The invention belongs to the field of bioengineering, and relates to a tumor targeting peptide targeting carcinoembryonic antigen-related cell adhesion molecule CEACAM6, and a preparation method and application thereof. Background Art

[0002] The Chinese neoadjuvant treatment guidelines for pancreatic cancer divide pancreatic cancer into resectable pancreatic cancer, borderline resectable pancreatic cancer, and locally advanced pancreatic cancer. Currently, surgical resection is the only way to cure pancreatic cancer, but only 20% of patients have the opportunity for surgery, because 80% of patients miss the best treatment period due to failure to receive timely diagnosis. Even if these patients undergo radical surgery, the chance of postoperative recurrence and metastasis is still high, and the median survival time is only 2 years. Cancer antigen 19-9 (CA19-9) is currently the only recognized serological marker for pancreatic cancer, but its diagnostic specificity and sensitivity are not high. Today, the diagnosis of pancreatic cancer mostly relies on traditional imaging examinations. With the rapid development of imaging technology and equipment, medical imaging, including multi-row CT (computer tomography), MRI (magnetic resonance imaging), and endoscopic ultrasound, play an important role in the diagnosis of pancreatic cancer. However, the diagnostic sensitivity of CT and MRI for pancreatic cancer less than 2 cm is only 50%-77%, and the disadvantages of endoscopic ultrasound are that it is invasive, highly dependent on the operator's experience, and requires careful response to accidents such as bleeding caused by vascular variations. Therefore, there is an urgent need to develop non-invasive, convenient, real-time dynamic imaging methods to achieve early diagnosis of tiny pancreatic cancer lesions and gain treatment time for pancreatic cancer patients.

[0003] Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is a member of the carcinoembryonic antigen gene family and the immunoglobulin (Ig) superfamily, and is composed of 12 immunoglobulin-related cell surface glycoproteins. These molecules play a role in cell signal transduction, cell adhesion, and tumorigenesis. CEACAM6 is considered to be an effective clinical biomarker for the diagnosis of pancreatic cancer. Clinical studies have found that 92% of pancreatic cancer patient samples are positive for CEACAM6; compared with primary and / or metastatic pancreatic cancer, the level of CEACAM6 in normal pancreas and other normal organs is significantly reduced. The CEA-targeted fluorescent drugs SGM-101 and ssSM3E / 800CW, which are still under study, both show specificity and sensitivity in the recognition of pancreatic tumors, which can further guide surgical resection. In addition, methods for treating malignant tumors targeting CEACAM6 have also developed rapidly, such as monoclonal antibodies, antibody-drug conjugates, immunotoxin therapy, gene knockout, and other methods. Therefore, CEACAM6 has become an attractive target for the diagnosis and treatment of pancreatic cancer and other tumors.

[0004] The polypeptide that specifically binds to the CEACAM6 receptor can be used as a targeting group for imaging probes. Using small molecule polypeptides as targeting groups is a commonly used targeting strategy, which has been widely applied in the field of tumor targeted therapy and the research on tumor targeted imaging is also gradually increasing. Compared with monoclonal antibodies, small molecule polypeptides have the advantages of weak immunogenicity, rapid distribution in vivo, strong penetrability, easy synthesis and modification, etc.

[0005] The clinical application of Positron Emission Computed Tomography (PET) technology has developed rapidly, which can achieve non-invasive imaging of various diseases and is of great significance for the early diagnosis, staging, treatment and prognosis of diseases. In theory, PET can detect the earliest tumors and tumor metastases with no obvious morphological changes. By analyzing the PET-CT diagnostic examination results of pancreatic cancer patients, it is proved that PET-CT has high sensitivity and accuracy and has great clinical value and significance. However, 18F-fluorodeoxyglucose (FDG, a commonly used PET imaging agent in clinical practice) approved by the FDA is not a tumor-specific tracer and can be taken up by normal and some benign lesion tissues, resulting in false positive and false negative results; 18 The early detection rate of 18F-FDG in pancreatic cancer is only 68.8%, and the detection accuracy of metastatic lymph nodes is also poor. Currently, the 68 68Ga-FAPI can specifically bind to fibroblast activation protein (FAP) and has successfully imaged various tumors, and the detection sensitivity for primary and metastatic lesions is higher than that of 18 18F-FDG. Therefore, developing a radionuclide-labeled probe with tumor-specific targeting has great research value and clinical significance for the early and accurate diagnosis, grading and identification of tiny lesions of tumors, so as to ensure that patients can receive timely treatment.

[0006] Single-Photon emission tomography / computerized tomography (SPECT / CT) is a new type of nuclear medicine imaging technology developed in the past 20 years. Because of its advantages such as high sensitivity, high resolution, non-invasiveness, traceable microdose and good imaging effect, SPECT / CT has been widely used in clinical diagnosis. In the present invention, a polypeptide that can specifically bind to the CEACAM6 receptor is conjugated with a radionuclide to prepare a radionuclide imaging probe targeting the CEACAM6 receptor. This probe can target and identify tumor cells and tumor foci with high expression of the CEACAM6 receptor in vivo and in vitro, and has good application prospects in the early diagnosis and treatment of tumors.

[0007] Optical imaging technology has the advantages of being non-invasive, safe, having strong visualization ability, high spatial resolution, and low cost. It can perform real-time and multi-dimensional visualization monitoring on biomolecules, cells, tissues, and organisms, and is an important research method in the field of biomedicine. Fluorescence imaging has good application prospects in biomolecule detection imaging, drug distribution and metabolism tracking, disease detection and diagnosis, especially in image-guided cancer treatment, due to its high sensitivity, high resolution, and simple operation. Moreover, fluorescence imaging can make up for the defect that radioactive PET probes cannot clearly and accurately depict the tumor boundary, and is more suitable for guiding intraoperative negative margins. Tumor-targeted probes have become a research hotspot in the field of tumor diagnosis and treatment due to their advantages of high sensitivity, strong specificity, and low background signal. The near-infrared fluorescent dye MPA has the advantages of deeper penetration depth and weaker autofluorescence of background tissues, and is more suitable for in vivo imaging. However, MPA cannot specifically bind to tumor cells. In the present invention, a polypeptide that can specifically bind to the CEACAM6 receptor is conjugated with the near-infrared fluorescent dye MPA to prepare a near-infrared fluorescent imaging probe targeting the CEACAM6 receptor. This probe can target and recognize tumor cells and tumor foci with high expression of the CEACAM6 receptor in vivo and in vitro, and has good application prospects in fluorescence imaging and fluorescence-guided surgery.

[0008] Therefore, specific targeting ligands are the key to radionuclide imaging and fluorescence imaging. Summary of the Invention

[0009] The object of the present invention is to provide a tumor-targeting peptide against carcinoembryonic antigen-related cell adhesion molecule CEACAM6 in view of the above deficiencies of the prior art.

[0010] Another object of the present invention is to provide the application of this tumor-targeting peptide.

[0011] The object of the present invention can be achieved by the following technical solutions:

[0012] A tumor-targeting peptide against carcinoembryonic antigen-related cell adhesion molecule CEACAM6, characterized in that it is selected from any one of the following polypeptides YQGR-X, X = 1-5:

[0013] YQGR-1, the sequence of which is His-Val-His-Leu-Leu-Gln-Ala-Lys-Asp-Ser-NH 2 as shown in the polypeptide;

[0014] YQGR-2, the sequence of which is His-Val-His-Leu-Leu-Gln-Ala-Lys-Asp-Cys-NH 2 as shown in the polypeptide;

[0015] YQGR-3, the sequence of which is His-Val(D)-His-Nle-Leu-Gln-Ala-Lys-Asp-Ser-NH 2 the polypeptide shown

[0016] YQGR-4, the sequence of which is His-Val(D)-Gly-Nle-Leu-Gln-Ala-Asn-Asn-Ser-NH 2 the polypeptide shown

[0017] YQGR-5, the sequence of which is Ser-Asp-Lys-Ala-Gln-Leu-Leu-His-Val-His-NH 2 the polypeptide shown;

[0018] D represents D-amino acid, and Nle is norleucine.

[0019] Application of the tumor-targeting peptide described in the present invention in the preparation of reagents for tumor diagnosis, treatment or tracing; preferably in the preparation of fluorescence imaging reagents or radioactive imaging reagents for tumor diagnosis or tracing.

[0020] The tumor mentioned is preferably a tumor with high expression of CEACAM6 receptor, and more preferably pancreatic cancer, breast cancer, lung cancer or colorectal cancer.

[0021] The polypeptide compound described in the present invention specifically targets carcinoembryonic antigen-related cell adhesion molecule (CEACAM6) to the tumor site, and has good aggregation and retention at the tumor site, with a high target-to-non-target ratio, and is suitable for use as a fluorescence tumor imaging agent, a radionuclide imaging agent and a therapeutic agent, and can be used for the preparation of an optical imaging drug for intraoperative tumor imaging navigation and precise tumor boundary localization.

[0022] A modified polypeptide having the following general formula:

[0023] M-L-YQGR-X, or M-YQGR-X,

[0024] wherein M represents a photo label or a radionuclide label;

[0025] L is a linking group;

[0026] YQGR-X is any one of the polypeptides described in the present invention.

[0027] The photo label is preferably selected from organic chromophores, organic fluorophores, light absorption compounds, light reflection compounds, light scattering compounds and bioluminescent molecules; the photo label is further preferably near-infrared fluorescent dyes MPA, IRDye800, Cy7.5, Cy5.5.

[0028] The radionuclide is preferably99m Tc, 68 Ga, 64 Cu, 67 Ga, 90 Y, 111 In or 177 Lu, 125 I.

[0029] The above-mentioned L is preferably pentyloic acid azide, propiolic acid, polyethylene glycol, 1,4,7-triazacyclononane-1,4,7-triacetic acid, 7-[(4-hydroxypropyl)methylene]-1,4,7-triazacyclononane-1,4-diacetic acid, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, mercaptoacetyltriglycine, MAG2, N3S, N2S2 ligands, diethylenetriaminepentaacetic acid, 1,4-succinic acid, 5-aminopentanoic acid, polyethyleneimine, 6-hydrazinylpyridine-3-carboxylic acid, benzyl bromoformate, N-(2-aminoacetic acid) maleimide, or a combination thereof.

[0030] The above-mentioned L is further preferably 6-aminohexanoic acid, PEG 4 , PEG 6 , HYNIC-PEG4 or any one or more of HYNIC.

[0031] When M represents a photo label, the modified polypeptide is a fluorescence molecular imaging probe for accurate localization of tumor boundaries and intraoperative imaging navigation. It is preferably conjugated by the polypeptide YQGR-X (X = 1-5) and the near-infrared fluorescent dye MPA. The preparation method is as follows:

[0032] (1) Dissolve 0.02 mmol of MPA in 200 μL of ultradry DMSO, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide (EDCI / NHS) (molar ratio of MPA:EDCI:NHS = 1:1.5:1.5), and react in the dark for 4 h for carboxyl activation reaction.

[0033] (2) Take 0.02 mmol of the solid-phase synthesized polypeptide YQGR-X (X = 1-5), 0.1 mmol of triethylamine and 200 μL of ultradry DMSO and add them to a 5 mL reaction flask, and react for 10 min under nitrogen protection; add the solution in the above reaction (1) to the reaction solution in (2), and stir and react at room temperature for 12 h;

[0034] (3) After the reaction is completed, the reaction solution is concentrated by freeze-drying, then diluted with distilled water, and loaded onto a C18 preparative column with a chromatographic packing of 10 μm. Gradient elution is carried out using high-performance liquid chromatography, and the eluted liquid of the target peptide is collected to detect the purity of the liquid. The eluate is rotary evaporated to remove acetonitrile, and finally freeze-dried using a freeze dryer. The resulting green solid product is the target fluorescent compound, and the mass-to-charge ratio is measured to determine the molecular weight.

[0035] When M represents a radionuclide label, the modified polypeptide is a radionuclide probe.

[0036] In some preferred embodiments of the present invention, the present invention uses radioactive iodine-125 to label the polypeptide YQGR-X (X = 1-5), and the labeling method is as follows:

[0037] The Iodogen oxidation method can be used to iodinate polypeptides containing tyrosine, histidine, and tryptophan residues. Since there is a histidine residue in the sequence of the polypeptide YQGR-X (X = 1-5), this method can be used for iodination. First, prepare Iodogen into a solid phase. Take 20 μL of the dichloromethane solution of Iodogen, and gently heat and blow dry with nitrogen to form a uniform Iodogen film on the EP tube. When performing the labeling, add a phosphate buffer solution (PH = 7.4) containing 5 μg of the peptide YQGR-X (X = 1-5) to the Iodogen EP tube, and then add 500 μCi of Na 125 I. After shaking the reaction at room temperature for 2 min, take out the reaction solution in the tube and dilute it with 50 μL of phosphate buffer solution (PH = 7.4). The radioactive mixture can be purified by passing through a C18 column to obtain the radioactive product 125 I-YQGR-X (X = 1-5). The radioactive labeled product is confirmed by high-performance liquid chromatography (HPLC) equipped with a radioactive detector.

[0038] In some other preferred embodiments of the present invention, the present invention uses a radionuclide 99m Tc to label the polypeptide YQGR-X (X = 1-5) to obtain a radionuclide 99m Tc-labeled probe, and its preparation method includes the following steps:

[0039] (1) Synthesis of the bifunctional chelator HYNIC-NHS

[0040] 6-chloronicotinic acid and 80% hydrazine hydrate were added to a 500 mL eggplant-shaped flask, and the mixture was heated under reflux for 6 h. After the reaction was completed, it was cooled to room temperature, diluted with distilled water, and then the pH was adjusted to about 5.3 to precipitate a solid. The solid was filtered and dried to obtain a pale yellow solid. The product was identified as 6-hydrazinonicotinic acid by ESI-MS mass spectrometry and 1H NMR. The obtained 6-hydrazinonicotinic acid and p-aminobenzaldehyde were added to dimethylformamide (DMF), and the mixture was heated and reacted for 2 h. After the reaction was completed, distilled water was added to precipitate a solid. After filtration and drying, it was added to DMF together with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI) and N-hydroxysuccinimide (NHS) and reacted at room temperature. After the reaction was completed, most of the solvent was evaporated, and water was added to precipitate a solid. The crude product was purified by silica gel column and identified as the target product by ESI-MS mass spectrometry and 1H NMR.

[0041] (2) Synthesis of HYNIC-YQGR-X (X = 1 - 5)

[0042] Purified 2 molar equivalents of HYNIC-NHS and 1 molar equivalent of polypeptide YQGR-X (X = 1 - 5) were dissolved in DMSO, and then 3 molar equivalents of triethylamine were added. The mixture was reacted at room temperature for 6 h, and the reaction progress was monitored by analytical high performance liquid chromatography. After the reaction was completed, it was separated and purified by preparative liquid chromatography, and finally confirmed by mass spectrometry.

[0043] (3) Radioactive probe 99m Synthesis of

[0044] A 5 mL mixture containing 5.0 mg of TPPTS (triphenylphosphine trisodium m-sulfonate), 6.5 mg of Tricine (trimethylglycine), 38.5 mg of disodium succinate hexahydrate, 12.7 mg of succinic acid and 10 μg of HYNIC-YQGR-X (X = 1 - 5) was prepared in a 10 mL vial, and then 10 - 50 mCi of Na 99m TcO4 solution was added, and the mixture was heated in a water bath at 100 °C for 15 minutes. After the reaction was completed, it was cooled to room temperature to prepare a polypeptide radiopharmaceutical, and the product was analyzed and identified by an Agilent ZORBAX SB-Aq analytical column.

[0045] In some other preferred embodiments of the present invention, the present invention uses the radionuclide 68 Ga to label the polypeptide YQGR-X (X = 1 - 5) to obtain a radionuclide 68 Ga-labeled probe, and its preparation method includes the following steps:

[0046] (1) Synthesis of DOTA-YQGR-X (X = 1 - 5)

[0047] Weigh 4 mg (3.8 μmol) of polypeptide YQGR-X (X = 1 - 5) into a 1.5 mL EP tube, dissolve it with dichloromethane (400 μL), then add DOTA-3tBu (4.4 mg, 7.6 μmol), HATU (3.6 mg, 9.5 μmol) and DIPEA (1.5 mg, 11.4 μmol), mix well. Place the reaction solution in a metal bath and stir at 40 °C for 6 h. Monitor the reaction by analytical liquid phase. After the reaction is completed, add 300 μL of trifluoroacetic acid to the reaction solution, stir and react for another 2 h, then rotary evaporate the solution to remove the solvent. Dilute the residue with water and acetonitrile, and purify it using an Agilent 1220 semi-preparative liquid phase.

[0048] (2) Radioactive probe 68 Preparation of Ga-DOTA-YQGR-X (X = 1 - 5)

[0049] First, prepare 0.05 M HCl aqueous solution and 0.25 M sodium acetate solution. Prepare the prepared DOTA-YQGR-X (X = 1 - 5) into a 10 μg / μL sodium acetate solution (0.25 M). Then rinse with 4 mL of 0.05 M HCl 68 Ge- 68 Ga generator, select 2 mL of eluate with the highest radioactivity in the middle for reaction. Add 20 mCi 68 Ga eluate into a vial, then add 0.5 mL of 0.25 M sodium acetate solution and 4 μL of DOTA-YQGR-X (X = 1 - 5) solution. Place the vial in a 100 °C water bath and heat react for 30 min. After the reaction is completed, cool to room temperature, then purify it using a C18 column (activated with 4 mL of 70% ethanol and 4 mL of normal saline), and measure the radioactivity of the sample loaded onto the column. Then rinse the C18 column 3 times with 1 mL of normal saline to remove the unlabeled 68 Ga. After the radioactivity of the C18 column is basically stable, rinse the C18 column with 0.2 mL of 60% ethanol to obtain the product. Measure the radioactivity with an activity meter and calculate the labeling yield. Use analytical liquid phase to detect the radiochemical purity (RCP).

[0050] The application of the modified polypeptide described in the present invention in the preparation of reagents for tumor diagnosis, treatment or tracing; preferably in the preparation of fluorescence imaging reagents or radioactive imaging reagents for tumor diagnosis or tracing.

[0051] The tumor is preferably a tumor with high expression of CEACAM6 receptor, more preferably pancreatic cancer, breast cancer, lung cancer or colorectal cancer.

[0052] Beneficial effects:

[0053] 1. The present invention provides a class of tumor-targeting peptides against carcinoembryonic antigen-related cell adhesion molecule (CEACAM6). These polypeptides can specifically target the tumor CEACAM6 receptor. Meanwhile, after coupling with fluorescent dyes, they can be used for optical imaging to accurately locate the tumor boundary for doctors during surgery, guide the resection of lesions, help improve the thoroughness of surgery, and thus improve the prognosis. In addition, this class of targeting polypeptides can also be coupled with radionuclides for radionuclide imaging to achieve the purpose of early diagnosis and treatment of tumors.

[0054] 2. These polypeptides are all low-molecular-weight polypeptides with low synthesis costs, and natural amino acids in this series of short peptides are replaced with non-natural amino acids, thereby improving the stability of the polypeptides in vivo.

[0055] 3. The peptides of the present invention are reported for the first time and are conveniently obtained.

[0056] 4. The YQGR-X (X = 1 - 5) series of polypeptides can specifically bind to tumor cells. The results of in vivo optical imaging and radionuclide imaging confirm that they have excellent imaging effects on various tumors, including pancreatic cancer, lung cancer, breast cancer, and colorectal cancer, etc.

[0057] 5. The present invention utilizes the advantages of the near-infrared fluorescent dye MPA, such as deeper penetration depth and weaker autofluorescence of background tissues, and has good application prospects in fluorescence imaging and fluorescence-guided surgery.

[0058] 6. The YQGR-X (X = 1 - 5) polypeptide radiopharmaceuticals can be used for tumor screening and early diagnosis, and can also monitor early malignant tumors and treatment in real time and non-invasively in situ. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is the structure of the fluorescent targeting compound MPA-YQGR-1.

[0060] Figure 2 It is the surgical navigation map of the compound MPA-YQGR-1 in pancreatic cancer PANC-1 tumor-bearing mice.

[0061] Figure 3 It is the optical imaging map of the compound MPA-YQGR-4 in pancreatic cancer CFPAC-1 tumor-bearing mice.

[0062] Figure 4 It is the blocking optical imaging map of the compound MPA-YQGR-4 in pancreatic cancer CFPAC-1 tumor-bearing mice

[0063] Figure 5 It is the targeting radiopharmaceutical 125 The structural diagram of I-YQGR-1.

[0064] Figure 6 It is the radiopharmaceutical125 SPECT imaging of I-YQGR-1 in nude mice bearing A549 lung cancer tumors.

[0065] Figure 7 is a radiopharmaceutical 125 SPECT imaging of I-YQGR-5 in nude mice bearing BxPC-3 pancreatic cancer tumors.

[0066] Figure 8 is a targeted radiopharmaceutical 99m Structural diagram of Tc-HYNIC-PEG4-YQGR-1.

[0067] Figure 9 is a radiopharmaceutical 99m SPECT imaging of Tc-HYNIC-PEG4-YQGR-1 in nude mice bearing BxPC-3 pancreatic cancer tumors.

[0068] Figure 10 is a radiopharmaceutical 99m SPECT imaging of Tc-HYNIC-PEG4-YQGR-1 in nude mice bearing colorectal cancer tumors (white arrow indicates HT29, red arrow indicates HCT116).

[0069] Figure 11 is a radiopharmaceutical 99m SPECT imaging of Tc-HYNIC-PEG4-YQGR-2 in nude mice bearing MCF-7 breast cancer tumors.

[0070] Figure 12 is a radiopharmaceutical 99m SPECT imaging of Tc-HYNIC-YQGR-3 in nude mice bearing lung cancer tumors (white arrow indicates H460, red arrow indicates A549).

[0071] Figure 13 is a radiopharmaceutical 99m SPECT imaging of Tc-HYNIC-YQGR-5 in nude mice bearing pancreatic cancer and liver cancer (negative) tumors (red arrow indicates CFPAC-1, white arrow indicates BEL-7404).

[0072] Figure 14 is a radiopharmaceutical 99m SPECT imaging of Tc-HYNIC-YQGR-5 in nude mice bearing SW1990 pancreatic cancer tumors.

[0073] Figure 15 is a targeted radiopharmaceutical 68 Structural diagram of Ga-DOTA-PEG4-YQGR-1.

[0074] Figure 16 is a radiopharmaceutical 68 PET-CT imaging of Ga-DOTA-PEG4-YQGR-1 in pancreatic cancer Panc-1 tumor-bearing mice

[0075] Figure 17 is a radiopharmaceutical 68 PET-CT imaging of Ga-DOTA-PEG4-YQGR-4 in pancreatic cancer CFPAC-1 tumor-bearing mice Detailed implementation methods

[0076] The present invention is further illustrated by the following specific examples and application examples: all chemical substances used in the synthesis steps are existing substances or commercially available products

[0077] Example 1 Preparation of YQGR-1

[0078] (1) Resin swelling

[0079] Add a certain amount of Rink Amide MBHA resin to the reaction column, then add an appropriate amount of dichloromethane (DCM), gently blow nitrogen for 10 - 30 minutes to fully swell the resin. Drain the dichloromethane solution, and then wash it 3 times with dimethylformamide (DMF) and drain it

[0080] (2) Deprotection of Fmoc

[0081] Add a 20% solution of piperidine in DMF to the reaction column, deprotect once every 5 minutes and once every 8 minutes. After the reaction is completed, wash the resin 3 times with DMF, DCM, and DMF in sequence

[0082] (3) Coupling

[0083] Accurately weigh 3 times the molar amount of the feeding resin of Fmoc-Ser-OH and O-benzotriazole-tetramethylurea hexafluorophosphate (HBTU), completely dissolve them in DMF, add N,N-diisopropylethylamine (DIPEA) to activate the carboxyl group, then add the solution to the reaction column for reaction. After 30 minutes of reaction, wash it 3 times with DMF, DCM, and DMF in sequence, then drain the solvent. Take a small amount of resin and add one drop each of 6% ninhydrin / ethanol solution and 80% phenol / ethanol solution for detection. If the condensation is complete and there is no free amino group, the solution will be colorless or light yellow; otherwise, the resin or the solution will turn blue or reddish-brown, indicating that the reaction is incomplete. After the reaction is completed, wash it 3 times with DMF, DCM, and DMF in sequence. Repeat the above operation and couple other amino acids in turn until the last amino acid Fmoc-His(trt)-OH is coupled. Wash the obtained peptidyl resin with methanol and dry it thoroughly in a vacuum drying oven

[0084] (4) Lysis

[0085] Take 120 mL of lysis solution (87.5% trifluoroacetic acid + 5% benzyl methyl sulfide + 2.5% ethanedithiol + 2.5% phenol + 2.5% water) and add it to the resin. Shake it at low temperature for 2 h, then separate the lysis solution from the resin using a sintered glass funnel and retain the filtrate. Slowly drip the filtrate into ice-cold anhydrous ether. After the dripping is complete, let it settle naturally for 30 min. Then centrifuge to obtain a solid, wash the solid three times with ether, and dry the obtained precipitate to get a crude dry powder.

[0086] (5) Purification

[0087] Purification is carried out by high performance liquid chromatography. The chromatographic packing material for purification is a 10 μm C18 preparative column. The mobile phase system is 0.1% TFA / aqueous solution - 0.1% TFA / acetonitrile solution. Gradient elution is used, and cyclic injection purification is carried out. Take the crude product solution and load it onto the chromatographic column. Start the elution of the mobile phase, collect the main peak, evaporate the acetonitrile, and obtain the target polypeptide concentrate. Then lyophilize it to obtain the target polypeptide YQGR-1, with the sequence His-Val-His-Leu-Leu-Gln-Ala-Lys-Asp-Ser-NH 2 , and finally measure the mass-to-charge ratio to determine the molecular weight to be 1146.63.

[0088] Prepare YQGR-2 according to the above method. The sequence is His-Val-His-Leu-Leu-Gln-Ala-Lys-Asp-Cys-NH 2 , and the molecular weight is confirmed by mass spectrometry to be 1162.38. YQGR-3, the sequence is His-Val(D)-His-Nle-Leu-Gln-Ala-Lys-Asp-Ser-NH 2 , and the molecular weight is confirmed by mass spectrometry to be 1145.62. YQGR-4, the sequence is His-Val(D)-Gly-Nle-Leu-Gln-Ala-Asn-Asn-Ser-NH 2 , and the molecular weight is confirmed by mass spectrometry to be 1050.56. The sialic acid ganglioside affinity peptide YQGR-5, the sequence is Ser-Asp-Lys-Ala-Gln-Leu-Leu-His-Val-His-NH 2 , and the molecular weight is confirmed by mass spectrometry to be 1145.64.

[0089] Example 2 Preparation of the fluorescent targeting compound MPA-YQGR-1

[0090] MPA is from a patent for invention previously applied by our research group, with the authorized patent number: CN101440282.

[0091] (1) Dissolve 12 mg of MPA in 200 μL of ultradry DMSO, add 3.7 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 2.2 mg of N-hydroxysuccinimide (EDCI / NHS) (molar ratio of MPA:EDCI:NHS = 1:1.5:1.5), react in the dark for 4 h to carry out the carboxyl activation reaction.

[0092] (2) Weigh 10 mg of the polypeptide YQGR-1 synthesized by solid-phase carrier, 6.5 mg of triethylamine and 200 μL of ultradry DMSO, add them to a 5 mL reaction flask, and react for 10 min under nitrogen protection; add the solution in the above reaction (1) to the reaction solution in (2), and stir and react at room temperature for 12 h;

[0093] (3) After the reaction is completed, concentrate the reaction solution by freeze-drying, then dilute it with distilled water, and separate and purify it by preparative liquid phase. The preparative liquid phase conditions are as follows: Use an Agilent 1220Infinity II series HPLC system equipped with an Agilent ZORBAX SB-C18 semi-preparative column (9.4×250 mm, 5 μm), gradient elution for 60 minutes, flow rate 2 mL / min, where mobile phase A is ultrapure water (0.01% TFA), and B is acetonitrile (0.01% TFA). The elution gradient is set as: 95% A and 5% B at 0 - 5 minutes, 85% A and 15% B at 15 minutes, 70% A and 30% B at 30 minutes, 50% A and 50% B at 45 minutes, and 10% A and 90% B at 60 minutes. The finally obtained green product is confirmed to be the expected product MPA-YQGR-1 by analytical HPLC and ESI-MS mass spectrometry (the structure is as Figure 1 shown). In the above preparation process, when the solid-phase synthesized YQGR-X (X = 2 - 5) polypeptide is used to replace the YQGR-1 polypeptide used in the steps, other various polypeptide compounds MPA-YQGR-2, MPA-YQGR-3, MPA-YQGR-4, MPA-YQGR-5 with tumor-targeted optical imaging functions of the present invention can be obtained.

[0094] Surgical navigation map of the compound MPA-YQGR-1 prepared in Example 3 in pancreatic cancer PANC-1 tumor-bearing mice.

[0095] Prepare the compound MPA-YQGR-1 prepared in Example 2 into a physiological saline solution (600 μg / mL), inject 100 μL of the drug MPA-YQGR-1 solution into pancreatic cancer PANC-1 tumor-bearing nude mice (weighing about 21 g) through the tail vein respectively, and collect optical signals at different time points after administration. Observe the distribution of the probe in the mouse body and its enrichment in the tumor area. After 24 h, the fluorescence signal in the tumor part is significant, and the normal tissues of the body basically disappear. The surgical navigation results are asFigure 2 as shown

[0096] Optical imaging map of compound MPA - YQGR - 4 in pancreatic cancer CFPAC - 1 tumor - bearing mice

[0097] The prepared compound MPA - YQGR - 4 was formulated into a physiological saline solution (600 μg / mL). 100 μL of the drug MPA - YQGR - 4 solution was injected into 3 pancreatic cancer CFPAC - 1 tumor - bearing nude mice (weighing about 21 g) through the tail vein respectively, and optical signal acquisition was carried out at 1 h, 2 h, 4 h, 8 h, 12 h and 24 h after administration. The distribution of the probe in the mice and its enrichment in the tumor region were observed. The imaging results of compound MPA - YQGR - 4 in the 3 tumor - bearing nude mice were basically the same. It can be seen from the imaging map at 2 h that the probe had obvious aggregation in the tumor, and the outline of the tumor edge was relatively clear. The probe still remained in the tumor until 24 h. The imaging results are as Figure 3 shown. Among them, the probe was most enriched in the tumor at 4 h, and its uptake and clearance in other background organs were relatively fast. It can be inferred from the signal of the bladder that this probe was mainly metabolized through the kidneys.

[0098] Optical imaging map of MPA - YQGR - 4 in pancreatic cancer CFPAC - 1 tumor - bearing mice after being blocked by polypeptide YQGR - 4

[0099] Unlabeled YQGR - 4 was formulated into a physiological saline solution of 5 mg / mL. 100 μL of the solution was injected into 3 pancreatic cancer CFPAC - 1 tumor - bearing nude mice (weighing about 21 g) respectively. 1 h later, 100 μL of the drug MPA - YQGR - 4 solution (600 μg / mL) was injected into these 3 pancreatic cancer CFPAC - 1 tumor - bearing nude mice through the tail vein, and optical signal acquisition was carried out at 1 h, 2 h, 4 h, 8 h, 12 h and 24 h after administration. The distribution of the probe in the mice and its enrichment in the tumor region were observed. The imaging results are as Figure 4 shown. The imaging results of the fluorescent probe MPA - YQGR - 4 in the 3 tumor - bearing nude mice were basically the same. It can be clearly seen from the optical images at each time point that after being blocked with compound YQGR - 4 in advance, no obvious fluorescent signal was seen in the tumor region, indicating that the binding of the probe MPA - YQGR - 4 to the tumor region in vivo was specific binding.

[0100] Example 6 Preparation of a targeted radiopharmaceutical 125 I - YQGR - 1

[0101] First, prepare an Iodogen dichloromethane solution at a concentration of 0.5 mg / mL. Take 20 μL of the Iodogen dichloromethane solution and place it in an EP tube. Gently heat it and blow it dry with nitrogen to form a uniform Iodogen film on the EP tube. Then, add 10 μL of the phosphate buffer solution (pH = 7.4) (1 mg / mL) of YQGR-1 peptide to the Iodogen EP tube, and then add 500 μCi of Na 125 I solution. After reacting with shaking at room temperature for 2 min, take out the reaction solution in the tube and add 50 μL of phosphate buffer solution (pH = 7.4) for dilution. After purification of the radioactive mixture through a Sep-Pak C18 column, the radioactive product 125 I-YQGR-1 can be obtained. 125 The labeling rate of Figure 5 I-YQGR-1 is >90%, and the radiochemical purity is >99% after purification through a Sep-Pak C18 column (the structure is as 125 shown). By replacing the YQGR-1 peptide used in the above steps with the solid-phase synthesized YQGR-X (X = 2 - 5) polypeptides, various other 125 I-labeled radiopharmaceuticals for SPECT-CT imaging of the present invention, such as 125 I-YQGR-2, 125 I-YQGR-3, 125 I-YQGR-4,

[0102] The 125 I-YQGR-1 prepared in Example 7 shows the SPECT imaging in A549 tumor-bearing mice with lung cancer.

[0103] Prepare the compound 125 I-YQGR-1 according to the method of Example 6 and formulate it into a physiological saline solution (1 mCi / mL). Take 0.2 mL (about 200 μCi) of the solution and inject it into the tail veins of 3 nude mice bearing A549 lung cancer tumors respectively. Perform SPECT signal acquisition at 0.5 h, 1 h, 2 h, 3 h, and 4 h after administration. Observe the distribution of the radionuclide probe in the mice and its accumulation in the tumor area. The imaging results at 1 h are as Figure 6 shown. The probe has obvious uptake at the tumor site, indicating that the radioactive probe 125 I-YQGR-1 can target A549 lung cancer tumor cells. It can be seen from the image that the metabolites are mainly excreted through the kidneys and a small amount through hepatic and intestinal metabolism.

[0104] The 125 I-YQGR-5 prepared in Example 8 shows the SPECT-imaging in BxPC-3 tumor-bearing mice with pancreatic cancer.

[0105] Prepare the compound according to the method of Example 6 125 I-YQGR-5 and formulate it into a physiological saline solution (1 mCi / mL). Take 0.2 mL (about 200 μCi) of the solution and inject it into 3 nude mice bearing pancreatic cancer BxPC-3 tumors via the tail vein respectively. Perform SPECT signal acquisition at 0.5 h, 1 h, 2 h, 3 h, and 4 h after administration. Observe the distribution of the radionuclide probe in the mouse body and its accumulation in the tumor region. The imaging results at 1 h are as shown in Figure 7 shown. The probe has obvious uptake at the tumor site, indicating that the radioactive probe 125 I-YQGR-5 can target pancreatic cancer BxPC-3 tumor cells. It can be seen from the image that the metabolites are mainly excreted through the kidneys and a small amount through hepatic and intestinal metabolism.

[0106] Example 9 Targeted Radiopharmaceutical 99m Tc-HYNIC-PEG4-YQGR-1

[0107] The present invention is used for 99m The synthesis of the Tc-labeled precursor compound HYNIC-PEG4-YQGR-X (X = 1 - 5) refers to Patent CN111675750A. Prepare a 5 mL mixture containing 5.0 mg of TPPTS (triphenylphosphine trisulfonate), 6.5 mg of Tricine (trimethylglycine), 38.5 mg of disodium succinate hexahydrate, 12.7 mg of succinic acid, and 20 μg of HYNIC-PEG4-YQGR-1 in a 10 mL vial. Then add 10 - 50 mCi of Na 99m TcO4 solution, heat it in a water bath at 100 °C for 15 minutes. After the reaction is completed, cool it to room temperature to prepare the polypeptide radiopharmaceutical. The product is identified using an HPLC system equipped with a radioactive on-line detector (Flow-RAM) and an Agilent ZORBAX SB-Aq analytical column (4.6 × 250 mm, 5 μm). Gradient elution is performed for 45 minutes at a flow rate of 1 mL / min. The mobile phase A is ultrapure water (0.01% TFA), and B is acetonitrile (0.01% TFA). The elution gradient is set as follows: 95% A and 5% B at 0 - 5 minutes, 85% A and 15% B at 15 minutes, 65% A and 35% B at 25 minutes, 50% A and 50% B at 35 minutes, and 10% A and 90% B at 45 minutes. 99m The labeling rate of Tc-HYNIC-PEG4-YQGR-1 > 95%, and the radiochemical purity > 99% after purification by Sep-Pak C18 column.

[0108] (The structural formula is as shown in Figure 8 )

[0109] Prepared in Example 10 99m SPECT imaging of Tc-HYNIC-PEG4-YQGR-1 in BxPC-3 tumor-bearing mice with pancreatic cancer.

[0110] The compound prepared by the method in Example 9 99m Tc-HYNIC-PEG4-YQGR-1 was formulated into a saline solution (1 mCi / mL). Three nude mice bearing BxPC-3 pancreatic cancer tumors (weighing about 23 g) were injected with 300 μL of the drug solution via the tail vein, and optical signal acquisition was performed at 0.5, 1.5 h, 2.5 h, and 4 h after administration. The distribution of the probe in the mice and its enrichment in the tumor region were observed. The imaging results are as Figure 9 shown. The radioactive probe 99m Tc-HYNIC-PEG4-YQGR-1 had obvious uptake at the tumor site, indicating that this probe could target BxPC-3 tumor cells of pancreatic cancer, and the metabolites were mainly excreted through the kidney-bladder.

[0111] Example 11 Radiopharmaceutical 99m SPECT imaging of Tc-HYNIC-PEG4-YQGR-1 in tumor-bearing mice with colorectal cancer.

[0112] The compound prepared according to Example 9 99m Tc-HYNIC-PEG4-YQGR-1 was formulated into a saline solution (1 mCi / mL). Three nude mice bearing bilateral tumors of colorectal cancer (weighing about 22 g) were injected with 300 μL of the drug solution via the tail vein, and optical signal acquisition was performed at 0.5, 1 h, 2 h, and 4 h after administration. The distribution of the probe in the mice and its aggregation in the tumor region were observed. The imaging results at 1 h are as Figure 10 shown (the white arrow indicates HT29, and the red arrow indicates HCT116). The radioactive probe 99m Tc-HYNIC-PEG4-YQGR-1 had obvious uptake at the tumor site, indicating that this probe could target HT29 and HCT116 tumor cells of colorectal cancer, and the metabolites were mainly excreted through the kidney-bladder.

[0113] Example 12 Radiopharmaceutical 99m SPECT imaging of Tc-HYNIC-PEG4-YQGR-2 in MCF-7 tumor-bearing mice with breast cancer.

[0114] The compound prepared by the same method as in Example 9 99mTc-HYNIC-PEG4-YQGR-2 was formulated into a saline solution (1 mCi / mL). Three nude mice bearing MCF-7 breast cancer tumors (weighing approximately 22 g) were injected with 300 μL of the drug solution via the tail vein, and optical signal acquisition was performed at 0.5, 1 h, 2 h, and 4 h after administration. The distribution of the probe in the mice and its accumulation in the tumor region were observed. The imaging results at 2 h are as Figure 11 shown, and the radioactive probe 99m Tc-HYNIC-PEG4-YQGR-2 showed significant uptake at the tumor site, indicating that this probe can target MCF-7 breast cancer tumor cells, and the metabolites are mainly excreted through the kidney-bladder.

[0115] Example 13 Radiopharmaceutical 99m SPECT imaging of Tc-HYNIC-YQGR-3 in nude mice bearing lung cancer tumors.

[0116] The compound prepared by the same method as in Example 9 99m Tc-HYNIC-YQGR-3 was formulated into a saline solution (1 mCi / mL). Three nude mice bearing bilateral lung cancer tumors (weighing approximately 22 g) were injected with 300 μL of the drug solution via the tail vein, and optical signal acquisition was performed at 0.5, 1 h, 2 h, and 4 h after administration. The distribution of the probe in the mice and its accumulation in the tumor region were observed. The imaging results at 2 h are as Figure 12 shown (the white arrow indicates H460, and the red arrow indicates A549), and the radioactive probe 99m Tc-HYNIC-YQGR-3 showed significant uptake at the tumor site, indicating that this probe can target lung cancer tumor cells H460 and A549, and the metabolites are mainly excreted through the kidney-bladder.

[0117] Example 14 Radiopharmaceutical 99m SPECT imaging of Tc-HYNIC-YQGR-5 in nude mice bearing pancreatic cancer and liver cancer (negative) tumors.

[0118] The compound prepared by the same method as in Example 9 99m Tc-HYNIC-YQGR-5 was formulated into a saline solution (1 mCi / mL). Three nude mice bearing pancreatic cancer and liver cancer (negative) tumors (weighing approximately 22 g) were injected with 300 μL of the drug solution via the tail vein, and optical signal acquisition was performed at 0.5, 1 h, 2 h, and 4 h after administration. The distribution of the probe in the mice and its accumulation in the tumor region were observed. The imaging results at 2 h are as Figure 13 shown (the red arrow indicates CFPAC-1, and the white arrow indicates BEL-7404), and the radioactive probe 99mTc-HYNIC-YQGR-5 showed obvious uptake at the tumor site, indicating that this probe could target CFPAC-1 tumor cells of pancreatic cancer. The metabolites were mainly excreted through the kidney-bladder. At the same time, it had no targeting effect on CEACAM6-negative tumor BEL-7404 of liver cancer, proving the specificity of the probe.

[0119] Example 15 Radiopharmaceutical 99m SPECT imaging of Tc-HYNIC-YQGR-5 in nude mice bearing SW1990 pancreatic cancer tumors.

[0120] Compound prepared by the same method as in Example 9 99m Tc-HYNIC-YQGR-5 was formulated into a saline solution (1 mCi / mL). 300 μL of the drug solution was injected into the tail veins of 3 nude mice bearing SW1990 pancreatic cancer tumors (weighing about 22 grams), and optical signal collection was performed at 0.5 h, 1 h, 2 h, and 4 h after administration. Observe the distribution of the probe in the mouse body and its accumulation in the tumor area. The imaging results at 2 h are as Figure 14 shown. The radioactive probe 99m Tc-HYNIC-YQGR-5 showed obvious uptake at the tumor site, indicating that this probe could target SW1990 pancreatic cancer tumor cells. The metabolites were mainly excreted through the kidney-bladder.

[0121] Example 16 Radiopharmaceutical 68 Preparation of Ga-DOTA-YQGR-1

[0122] First, prepare 0.05 M HCl aqueous solution and 0.25 M sodium acetate solution. The prepared DOTA-YQGR-1 was formulated into a 10 μg / μL sodium acetate solution (0.25 M). Then, 4 mL of 0.05 M HCl was used to elute 68 Ge- 68 Ga generator. Select 2 mL of the eluate with the highest radioactivity in the middle for reaction. Add 20 mCi 68 Ga eluate into a vial, then add 0.5 mL of 0.25 M sodium acetate solution and 4 μL of DOTA-YQGR-1 solution. Place the vial in a 100 °C water bath for heating reaction for 30 min. After the reaction, cool to room temperature, and then use a C18 column for purification (activated with 4 mL of 70% ethanol and 4 mL of normal saline). Measure the radioactivity of the sample loaded onto the column. Then, rinse the C18 column 3 times with 1 mL of normal saline to remove the unlabeled 68 Ga. After the radioactivity of the C18 column was basically stable, elute the C18 column with 0.2 mL of 60% ethanol to obtain the product. Measure the radioactivity with an activity meter and calculate the labeling yield. Use analytical liquid chromatography to detect the radiochemical purity (RCP). (The structural formula is asFigure 15 as shown

[0123] Example 17 Radiopharmaceutical 68 PET-CT imaging of Ga-DOTA-PEG4-YQGR-1 in pancreatic cancer Panc-1 tumor-bearing mice.

[0124] The compound prepared according to Example 16 68 Ga-DOTA-PEG4-YQGR-1 was formulated into a saline solution (1 mCi / mL). 150 μL of the drug solution was injected into 3 nude mice bearing Panc-1 pancreatic cancer tumors (weighing about 22 g) via the tail vein, and optical signal collection was performed at 0.5, 1 h, and 2 h after administration. Observe the distribution of the probe in the mice and its accumulation in the tumor area. The imaging results at 1 h are as Figure 16 shown, the radioactive probe 68 Ga-DOTA-PEG4-YQGR-1 had obvious uptake at the tumor site, indicating that this probe could target Panc-1 pancreatic cancer tumor cells, and the metabolites were mainly excreted through the kidney-bladder.

[0125] Example 18 Radiopharmaceutical 68 PET-CT imaging of Ga-DOTA-PEG4-YQGR-4 in pancreatic cancer CFPAC-1 tumor-bearing mice.

[0126] The compound prepared in the same manner as in Example 16 68 Ga-DOTA-PEG4-YQGR-4 was formulated into a saline solution (1 mCi / mL). 150 μL of the drug solution was injected into 3 nude mice bearing CFPAC-1 pancreatic cancer tumors (weighing about 22 g) via the tail vein, and optical signal collection was performed at 0.5, 1 h, and 2 h after administration. Observe the distribution of the probe in the mice and its accumulation in the tumor area. The imaging results are as Figure 17 shown, the radioactive probe 68 Ga-DOTA-PEG4-YQGR-4 had obvious uptake at the tumor site, indicating that this probe could target CFPAC-1 pancreatic cancer tumor cells, and the metabolites were mainly excreted through the kidney-bladder.

[0127] Based on the principle of specific binding between the polypeptide YQGR-X (X = 1 - 5) and the CEACAM6 receptor, and taking advantage of the high expression of the CEACAM6 receptor in malignant tumors such as pancreatic cancer, lung cancer, breast cancer, and colorectal cancer, as well as the deeper penetration depth and weaker autofluorescence of background tissues of the near-infrared fluorescent dye MPA, it can target and identify tumor cells and tumor foci with high expression of the CEACAM6 receptor, and has good application prospects in fluorescence imaging and fluorescence-guided surgery. At the same time, this series of polypeptides can also be conjugated with radionuclides, and the drug after in vivo radionuclide labeling can accumulate in the tumor site through the targeting effect of the polypeptide YQGR-X (X = 1 - 5). Using the single-photon (SPECT) and positron (PET) tomography imaging techniques of nuclear medicine, various tumors can be imaged and diagnosed. The present invention relates to the field of drugs related to tumor diagnosis, and specifically relates to multiple polypeptides, as well as pharmaceutical compositions containing these polypeptides as active ingredients and their applications in the preparation of diagnostic drugs.

Claims

1. A tumor-targeting peptide against carcinoembryonic antigen-related cell adhesion molecule CEACAM6, characterized in that it is selected from any of the following polypeptides: YQGR-1, the sequence is shown in SEQ ID NO.1, specifically His-Val-His-Leu-Leu-Gln-Ala-Lys-Asp-Ser-NH 2 .

2. Use of the tumor-targeting peptide according to claim 1 in the preparation of a reagent for tracing pancreatic cancer, lung cancer or colorectal cancer with positive CEACAM6.

3. Use of the tumor-targeting peptide according to claim 1 in the preparation of a fluorescence imaging reagent or a radioactive imaging reagent for tracing pancreatic cancer, lung cancer or colorectal cancer with positive CEACAM6.

4. A modified polypeptide, characterized in that it has the following general formula: M-L-YQGR-1, or M-YQGR-1, wherein M represents a photo-label or a radionuclide label; L is a linking group; YQGR-1 is the polypeptide according to claim 1.

5. The modified polypeptide according to claim 4, characterized in that the photo-label is selected from organic chromophores, fluorescent dyes, light-absorbing compounds, light-reflecting compounds, light-scattering compounds and bioluminescent molecules.

6. The modified polypeptide according to claim 4, characterized in that the photo-label is selected from fluorescent dyes.

7. The modified polypeptide according to claim 6, characterized in that the photo-label is selected from near-infrared fluorescent dyes.

8. The modified polypeptide according to claim 6, characterized in that the photo-label is selected from MPA, IRDye800, Cy7.5, Cy5.

5.

9. The modified polypeptide according to claim 4, characterized in that The radioactive nuclides described are selected from 99m Tc,[[]] 68 Ga,[[]] 64 Cu,[[]] 67 Ga,[[]] 90 Y,[[]] 111 In,[[]] 177 Lu or 125 I.[[]] 10. The modified polypeptide according to claim 4, characterized in that the L is selected from azidovaleric acid, propiolic acid, polyethylene glycol, 1,4,7-triazacyclononane-1,4,7-triacetic acid, 7-[(4-hydroxypropyl)methylene]-1,4,7-triazacyclononane-1,4-diacetic acid, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, mercaptoacetyltriglycine, MAG2, N3S, N2S2 ligands, diethylenetriaminepentaacetic acid, 1,4-succinic acid, 5-aminopentanoic acid, polyethyleneimine, 6-hydrazinopyridine-3-carboxylic acid, benzyl bromoformate, N-(2-aminoacetic acid)maleimide, 6-aminohexanoic acid, HYNIC-PEG4 or HYNIC or a combination thereof.

11. The modified polypeptide according to claim 10, characterized in that The aforementioned L is selected from any one or more of 6 - aminocaproic acid, PEG 4 , PEG 6 , HYNIC - PEG4 or HYNIC.

12. Use of the modified polypeptide according to any one of claims 4 to 11 in the preparation of a reagent for tracing pancreatic cancer, lung cancer or colorectal cancer with positive CEACAM6.

13. The use according to claim 12, characterized in that the modified polypeptide according to any one of claims 4 to 11 is used in the preparation of a fluorescence imaging reagent or a radioactive imaging reagent for tracing pancreatic cancer, lung cancer or colorectal cancer with positive CEACAM6.

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