CN116444666A

CN116444666A - Preparation method and application of CDH17 specific diagnosis and treatment integrated molecular imaging probe

Info

Publication number: CN116444666A
Application number: CN202310578476.2A
Authority: CN
Inventors: 魏伟军; 潘心冰; 刘建军
Original assignee: Renji Hospital Shanghai Jiaotong University School of Medicine
Current assignee: Renji Hospital Shanghai Jiaotong University School of Medicine
Priority date: 2023-05-22
Filing date: 2023-05-22
Publication date: 2023-07-18

Abstract

The invention relates to the technical fields of molecular imaging, nuclear medicine and nanobody for tumor diagnosis and treatment, in particular to a preparation method and application of a CDH17 specific diagnosis and treatment integrated molecular imaging probe. The CDH17 specific molecular imaging probe realizes noninvasive visualization of human CDH17 molecular expression, and further realizes noninvasive diagnosis of colorectal cancer; the probe has the advantages of simple preparation process, low cost, high specificity, high stability, short imaging period, low radiation dose, easy clinical transformation and the like; and screening patients with high CDH17 expression, and further developing CDH17 specific radioimmunotherapy, so as to realize target specific diagnosis and treatment integration of CDH17 expression positive tumors.

Description

Preparation method and application of CDH17 specific diagnosis and treatment integrated molecular imaging probe

Technical Field

The invention relates to the technical fields of molecular imaging, nuclear medicine and nanobody for tumor diagnosis and treatment, in particular to a preparation method and application of a CDH17 specific diagnosis and treatment integrated molecular imaging probe.

Background

In 1993, belgium scientists Hamers et al reported for the first time in Nature journal that an antibody with a naturally deleted light chain was present in alpaca peripheral blood (Nature.1993; 363 (6428): 446-8.), an antibody with a specific domain, namely Heavy chain antibodies (HCAbs). Through molecular biological means, the antigen binding fragment of only the heavy chain variable region can be obtained by cloning the variable region of the heavy chain antibody, namely the nanobody (VHH, variable Domain of Heavy Chain of Heavy Chain Antibody). VHH crystals are 2.5nm wide and 4nm long and have a molecular weight of only 15kDa, and are therefore also known as nanobodies [ (] Ablynx corporation registers trade names). The nano antibody is the currently known minimum antibody unit capable of combining the target antigen, and has the advantages of high affinity, small molecular weight, low preparation cost (not only can be expressed by using escherichia coli, but also can be expressed by using eukaryotic expression systems such as yeast, chinese hamster ovary cells and the like), and easy clinical transformation and popularization and application.

Nanobodies are popular targeting vectors for constructing molecular imaging probes in recent years (theranostics.2014; 4 (4): 386-98;J Nucl Med.2022Oct;63 (10): 1705-1709). Currently, a variety of short half-life nuclides have been used to label nanobodies and prepare nanobody molecular imaging probes. Technetium-99 m% ^99m Tc；T _1/2 =6.02 h) nanobody probes labeled targeting programmed death ligand 1 (PD-L1) have been successfully transformed into the clinic for non-invasive diagnosis of non-small cell lung cancer patients (J nucleic med.2019;60 1213-1220.); gallium-68% ⁶⁸ Ga；T _1/2 =1.1h) labeled human epidermal growth factor receptor (HER 2) -targeted nanobody probes have also been successfully transformed into clinic for noninvasive diagnosis of breast cancer (J nucleic med.2016;57 (1):27-33.). The above examples illustrate that the radionuclide-labeled nanobody probe has great clinical transformation application prospect, and can be used for early noninvasive diagnosis of human malignant tumor, visualization of key pathogenic targets, screening of patients treated by monoclonal antibodies (mAbs) and evaluation of curative effects after monoclonal antibody treatment.

Liver and intestine cadherin CDH17 is a calcium dependent membrane associated protein, a member of the cadherin superfamily. CDH17 has seven extracellular domains, a transmembrane region, and a short cytoplasmic domain that is not homologous to the highly conserved cytoplasmic domain of classical cadherins. Unlike classical cadherins, CDH17 does not induce up-regulation of β -catenin expression and actin cytoskeletal reorganization, the adhesive properties of which are primarily determined by the extracellular domain. Normally, CDH17 is expressed predominantly in the intestinal and colonic intestinal epithelium of adults, playing an important role in organ development and maintenance of tissue integrity and intestinal peptide transport. In recent years, it has been found that abnormal expression of CDH17 is significantly associated with a high incidence of many digestive tract tumors. In liver cancer, CDH17 expression is elevated in about 80% of patients and distributed in the cell membrane and cytoplasm. In addition to the increase in the expression level, abnormal spliceosomes such as CDH17 deleted from exon 7 are also present in liver cancer cells. CDH17 is not expressed in normal gastric epithelial cells, whereas CDH17 overexpression in gastric cancer, especially intestinal gastric cancer, is closely related to adverse pathological features such as histological stage, tumor infiltration, lymph node metastasis, etc., and is an important index for predicting tumor progression and prognosis. For primary colorectal cancer, research shows that CDH17 expression down-regulation can inhibit invasion and metastasis of colon cancer cells, and tissue chip analysis shows that CDH17 is over-expressed in colorectal adenocarcinoma, is an immunohistochemical marker for diagnosing colorectal adenocarcinoma, and has better sensitivity than CDX2. Therapeutically, when CDH17 is inhibited, β -catenin and phosphorylated glycogen synthesis kinase 3 β (GSK-3 β) synthesis is reduced and aberrant localization results in inhibition of Wnt signaling pathway, thereby inhibiting tumor growth. At present, research on monoclonal antibodies, chimeric antigen receptor T cells and the like taking CDH17 as targets is underway, and better therapeutic effects are shown. In general, CDH17 is an effective diagnostic and therapeutic target for digestive tract tumors, and development of a diagnostic tool targeting CDH17 to enable visualization and monitoring of CDH17 expression in solid tumors is urgently needed. On the basis of research accompanying diagnostic tools, new therapeutic approaches to CDH17 can be further developed.

Early series of basic and clinical studies by the applicant showed that by subtly fusing the extraordinary targeting specificity of antibodies with the superior sensitivity and resolution of Positron Emission Tomography (PET), immunopet can better show the distribution and abundance of targets of interest in vivo, particularly heterogeneous expression, and better predict response to targeted or immunotherapy (Chem rev.2020;120 (8): 3787-3851.) compared to Immunohistochemical staining (IHC) or other conventional predictive markers. For example, the value of immune PET imaging probes targeting HER 2 in breast cancer has been clinically demonstrated. Furthermore, there has been evidence that Radioimmunotherapy (RIT) and pretargeted radioimmunotherapy (pr it) may help tumor patients alleviate the condition for a long period of time, even eradicating multiple cancer types.

At present, no report of CDH17 specific molecular imaging probes or nuclide labeled diagnosis and treatment integrated probes exists in clinical practice and literature reports. The use of radiolabeled monoclonal antibodies is severely hampered by the high cost, necessity of using long half-life radionuclides, cumbersome imaging procedures within a week, and associated radiation exposure. In order to improve the clinical application of antibody diagnostics, the molecular imaging field is actively exploring pretargeting imaging strategies or using smaller molecular weight antibody derivatives to achieve the current day molecular imaging (same-day imaging). In the small antibody format, the nanobody or single domain antibody from the family camelidae is the smallest antigen binding portion with a molecular weight of about 15 kDa. The small size, high affinity and ease of engineering makes nanobodies an excellent alternative to molecular imaging (J NuclMed.2022Oct;63 (10): 1705-1709.). In recent years, we have focused on the development and clinical transformation of nanobody-derived tracers to exert their superior molecular imaging properties. Although radiolabeled monovalent nanobodies are ideal companion diagnostic tools, the half-life in vivo is too short and the renal uptake is high, leaving room for further improvement. At present, no CDH17 specific nano antibody molecule image probe exists at home and abroad.

Therefore, those skilled in the art are still working to develop a nanobody immune PET imaging probe which has low preparation cost, small molecular weight, short in vivo circulation time, short imaging period, low radiation dose and easy clinical transformation application.

Disclosure of Invention

To solve the above problems, the inventors herein describe the construction of nanobody-derived CDH 17-specific nanobody molecular imaging probes and characterize them in cell-derived xenograft (CDX) mouse models. It was found that an immune PET imaging probe targeting CDH17 can non-invasively show intratumoral CDH17 expression and provide a better method for diagnosis and monitoring of CDH17 positive solid tumors. Furthermore, the inventor introduces Albumin Binding Domain (ABD) targeting human/mouse albumin into monovalent nanobody, which successfully and remarkably prolongs half-life period of monovalent nanobody derivative in organism, and further optimizes pharmacokinetics and pharmacodynamics of molecular imaging probe. The research of the invention shows that the bispecific nanometer antibody derivative targeting tumor antigen and albumin simultaneously improves the in vivo biodistribution condition and can be used as a carrier for developing a therapeutic diagnostic kit.

CDH17 specific nanobody

In one aspect, the invention provides a CDH17 specific nanobody comprising: (1) CDR1 having the amino acid sequence shown in SEQ ID No.1, CDR2 having the amino acid sequence shown in SEQ ID No.2 and CDR3 having the amino acid sequence shown in SEQ ID No.3, or (2) CDR1 having the amino acid sequence shown in SEQ ID No.6, CDR2 having the amino acid sequence shown in SEQ ID No.7 and CDR3 having the amino acid sequence shown in SEQ ID No. 8.

More specifically, the CDH17 specific nanobody of the invention has the amino acid sequence shown in SEQ ID No.4 or 9.

In the present invention, for the sake of simplicity, the CDH 17-specific nanobody having the amino acid sequence shown in SEQ ID No.4 or 9 is referred to as CDH1 or CDH2, respectively.

As used herein, the term "nanobody" has the meaning commonly understood by those skilled in the art and refers to an antibody fragment consisting of a single monomer variable antibody domain (e.g., a single heavy chain variable region), typically derived from a variable region of a heavy chain antibody (e.g., a camelid antibody or a shark antibody). Typically, nanobodies consist of 4 framework regions and 3 complementarity determining regions, having the structure FR1-CDR1-FR2-CDR2-FR3-CDR3-FR 4. Nanobodies may be truncated at the N-or C-terminus such that they comprise only a portion of FR1 and/or FR4, or lack one or both of those framework regions, so long as they substantially retain antigen binding and specificity. Nanobodies are also known as single-domain antibodies (sdabs) or VHH (Variable Domain of Heavy Chain of Heavy Chain Antibody), which are used interchangeably.

In some embodiments, the invention also encompasses antigen binding fragments of CDH 17-specific nanobodies as described herein.

As used herein, the term "antigen-binding fragment" refers to a polypeptide comprising a fragment of a nanobody that retains the ability to specifically bind to the same antigen to which the nanobody binds, and/or competes with the nanobody for specific binding to an antigen, also referred to as an "antigen-binding portion. Generally, see Fundamental Immunology, ch.7 (Paul, W., ed., 2 nd edition, raven Press, N.Y. (1989), which is incorporated herein by reference in its entirety for all purposes, antigen binding fragments of the present antibodies may be produced by recombinant DNA techniques or by enzymatic or chemical cleavage of the present nanobodies.

Antigen-binding fragments of nanobodies can be obtained from a given nanobody (e.g., a nanobody provided by the invention) using conventional techniques known to those skilled in the art (e.g., recombinant DNA techniques or enzymatic or chemical cleavage methods), and specifically screened in the same manner as for whole nanobodies.

In this context, unless the context clearly indicates otherwise, when referring to the term "nanobody" it includes not only whole nanobodies but also antigen-binding fragments of nanobodies.

As used herein, the term "complementarity determining region" or "CDR" refers to the amino acid residues in an antibody variable region that are responsible for antigen binding. Three CDRs are contained in the nanobody, designated CDR1, CDR2 and CDR3. The precise boundaries of these CDRs may be defined according to various numbering systems known in the art, e.g., as in the Kabat numbering system (Kabat et al, sequences of Proteins of Immunological Interest,5thEd.Public Health Service,National Institutes of Health,Bethesda,Md, 1991), the Chothia numbering system (Chothia & Lesk (1987) J.mol. Biol.196:901-917; chothia et al (1989) Nature 342:878-883) or the IMGT numbering system (Lefranc et al, dev. Comparat. Immunol.27:55-77,2003). For a given nanobody, one skilled in the art will readily identify the CDRs defined by each numbering system. Also, the correspondence between the different numbering systems is well known to those skilled in the art (see, e.g., lefranc et al, dev. Comparat. Immunol.27:55-77,2003).

As used herein, the term "framework region" or "FR" residues refer to those amino acid residues in the variable region of an antibody other than the CDR residues as defined above.

As used herein, the term "CDH17 specific" refers to specifically binding CDH17.

As used herein, the term "specific binding" refers to a non-random binding reaction between two molecules, such as a reaction between an antibody and an antigen against which it is directed. The strength or affinity of a specific binding interaction can be determined by the equilibrium dissociation constant (K _D ) And (3) representing. In the present invention, the term "K _D "refers to dissociation of a particular antibody-antigen interactionConstant, which is used to describe the binding affinity between an antibody and an antigen. The smaller the equilibrium dissociation constant, the tighter the antibody-antigen binding, and the higher the affinity between the antibody and antigen.

The specific binding properties between two molecules can be determined using methods well known in the art. One method involves measuring the rate of antigen binding site/antigen complex formation and dissociation. "binding Rate constant" (k) _a Or k _on ) And "dissociation rate constant" (k) _dis Or k _off ) Both can be calculated from the concentration and the actual rate of association and dissociation (see Malmqvist M, nature,1993, 361:186-187). k (k) _dis /k _on Is equal to the dissociation constant K _D (see Davies et al, annual Rev Biochem,1990; 59:439-473). K can be measured by any effective method _D 、k _on And k _dis Values. In certain embodiments, the dissociation constant may be measured in Biacore using Surface Plasmon Resonance (SPR). In addition to this, bioluminescence interferometry or Kinexa can be used to measure the dissociation constant.

In some embodiments, the invention also provides variants of a CDH 17-specific nanobody as described herein that have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to the amino acid sequence set forth in SEQ ID No.4 or 9, and substantially retain the biological function of the nanobody from which it is derived (e.g., the biological activity of specifically binding to CDH 17).

More specifically, the variants differ from CDH 17-specific nanobodies as described herein only in conservative substitutions of one or more (e.g., conservative substitutions of up to 20, up to 15, up to 10, up to 5, or up to 1) amino acid residues.

As used herein, the term "identity" is used to refer to the match of sequences between two polypeptides or between two nucleic acids. When a position in both sequences being compared is occupied by the same base or amino acid monomer subunit (e.g., a position in each of two DNA molecules is occupied by adenine, or a position in each of two polypeptides is occupied by lysine), then the molecules are identical at that position. The "percent identity" between two sequences is a function of the number of matched positions shared by the two sequences divided by the number of positions to be compared x 100. For example, if 6 out of 10 positions of two sequences match, then the two sequences have 60% identity. For example, the DNA sequences CTGACT and CAGGTT share 50% identity (3 out of 6 positions in total are matched). Typically, the comparison is made when two sequences are aligned to produce maximum identity. Such alignment may be conveniently performed using, for example, a computer program such as the Align program (DNAstar, inc.) Needleman et al (1970) j.mol.biol.48: 443-453. The percent identity between two amino acid sequences can also be determined using the algorithms of E.Meyers and W.Miller (Comput. ApplBiosci.,4:11-17 (1988)) which have been integrated into the ALIGN program (version 2.0), using the PAM120 weight residue table (weight residue table), the gap length penalty of 12 and the gap penalty of 4. Furthermore, percent identity between two amino acid sequences may be determined using the Needleman and Wunsch (J mobiol. 48:444-453 (1970)) algorithm that has been incorporated into the GAP program of the GCG software package (available on www.gcg.com), using the Blossum 62 matrix or PAM250 matrix, and GAP weights (GAP weights) of 16, 14, 12, 10, 8, 6, or 4, and length weights of 1, 2, 3, 4, 5, or 6.

As used herein, the term "conservative substitution" means an amino acid substitution that does not adversely affect or alter the desired properties of a protein/polypeptide comprising the amino acid sequence. For example, conservative substitutions may be introduced by standard techniques known in the art, such as site-directed mutagenesis and PCR-mediated mutagenesis. Conservative amino acid substitutions include substitutions that replace an amino acid residue with an amino acid residue having a similar side chain, such as substitutions with residues that are physically or functionally similar (e.g., of similar size, shape, charge, chemical nature, including the ability to form covalent or hydrogen bonds, etc.) to the corresponding amino acid residue. Families of amino acid residues with similar side chains have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, and histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine, tryptophan), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine), beta-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Thus, it is preferred to replace the corresponding amino acid residue with another amino acid residue from the same side chain family. Methods for identifying conservative substitutions of amino acids are well known in the art (see, e.g., brummell et al, biochem.32:1180-1187 (1993); kobayashi et al Protein Eng.12 (10): 879-884 (1999); and Burks et al Proc. Natl Acad. Set USA 94:412-417 (1997), which are incorporated herein by reference).

CDH17 specific nanobody fusion proteins

In another aspect, the invention provides a CDH17 specific nanobody fusion protein comprising a nanobody and an albumin binding domain as described herein.

More specifically, the albumin binding domain has the amino acid sequence shown in SEQ ID No.11 or 12.

In the CDH 17-specific nanobody fusion proteins provided herein, the nanobody and albumin binding domain as described herein may be provided with a linker peptide. The linker peptide may be a flexible polypeptide chain consisting of alanine (A) and/or serine (S) and/or glycine (G), and may be 3 to 30 amino acids, for example 3 to 9, 9 to 12, 12 to 16 or 16 to 20 amino acids in length.

In a specific embodiment, the invention provides a CDH17 specific nanobody fusion protein having the amino acid sequence shown in SEQ ID No.13 or 15.

In the present invention, for the sake of simplicity, the CDH 17-specific nanobody fusion protein having the amino acid sequence shown in SEQ ID No.13 or 15 is referred to as ACDH17.1 or ACDH17.2, respectively.

Polynucleotide

In another aspect, the present invention also provides a polynucleotide encoding the above nanobody or antigen-binding fragment thereof or fusion protein thereof.

More specifically, the polynucleotide has the nucleotide sequence shown as SEQ ID No.5, 10, 14 or 16.

More specifically, the polynucleotide encoding a CDH17 specific nanobody as described herein has the nucleotide sequence shown in SEQ ID No.5 or 10. More specifically, the polynucleotide encoding a CDH17 specific nanobody fusion protein as described herein has the nucleotide sequence shown in SEQ ID No.14 or 16.

The polynucleotides of the invention may be in the form of DNA or RNA. DNA forms include cDNA, genomic DNA, or synthetic DNA. The DNA may be single-stranded or double-stranded. The DNA may be a coding strand or a non-coding strand.

The term "polynucleotide encoding a polypeptide/protein/antibody" may include polynucleotides encoding such polypeptide/protein/antibody, as well as polynucleotides further comprising additional coding and/or non-coding sequences.

The invention also relates to polynucleotides which hybridize to the sequences described above and which have at least 50%, preferably at least 70%, more preferably at least 80%, most preferably at least 90% identity between the two sequences, and which encode polypeptides/proteins/antibodies having substantially the same function and activity. The invention relates in particular to polynucleotides which hybridize under stringent conditions to the polynucleotides of the invention. In the present invention, "stringent conditions" means: (1) Hybridization and elution at lower ionic strength and higher temperature, e.g., 0.2 XSSC, 0.1% SDS,60 ℃; or (2) adding denaturing agents such as 50% (v/v) formamide, 0.1% calf serum/0.1% Ficoll,42℃and the like during hybridization; or (3) hybridization only occurs when the identity between the two sequences is at least 90% or more, more preferably 95% or more.

The full-length nucleotide sequence of the antibody of the present invention or a fragment thereof can be generally obtained by a PCR amplification method, a recombinant method or an artificial synthesis method. One possible approach is to synthesize the sequences of interest by synthetic means, in particular with short fragment lengths. In general, fragments of very long sequences are obtained by first synthesizing a plurality of small fragments and then ligating them. In addition, the heavy chain coding sequence and the expression tag (e.g., 6 His) may be fused together to form a fusion protein.

Carrier body

In another aspect, the invention also provides a vector comprising a polynucleotide encoding the nanobody or antigen-binding fragment thereof or fusion protein thereof described above.

As used herein, the term "vector" refers to a nucleic acid vehicle into which a polynucleotide may be inserted. When a vector enables expression of a protein encoded by an inserted polynucleotide, the vector is referred to as an expression vector. The vector may be introduced into a host cell by transformation, transduction or transfection such that the genetic material elements carried thereby are expressed in the host cell. Vectors are well known to those skilled in the art and include, but are not limited to: a plasmid; phagemid; a cosmid; artificial chromosomes, such as Yeast Artificial Chromosome (YAC), bacterial Artificial Chromosome (BAC), or P1-derived artificial chromosome (PAC); phages such as lambda phage or M13 phage, animal viruses, etc. Animal viruses that may be used as vectors include, but are not limited to, retrovirus (including lentivirus), adenovirus, adeno-associated virus, herpes virus (e.g., herpes simplex virus), poxvirus, baculovirus, papilloma virus, papilloma vacuolation virus (e.g., SV 40). A vector may contain a variety of elements that control expression, including, but not limited to, promoter sequences, transcription initiation sequences, enhancer sequences, selection elements, and reporter genes. In addition, the vector may also contain a replication origin.

Host cells

In another aspect, the invention also provides a host cell comprising a vector as described herein.

As used herein, the term "host cell" refers to a cell that can be used to introduce a vector, including, but not limited to, a prokaryotic cell such as e.g. escherichia coli or bacillus subtilis, a fungal cell such as e.g. yeast cells or aspergillus, an insect cell such as e.g. S2 drosophila cells or Sf9, or an animal cell such as e.g. fibroblasts, CHO cells, COS cells, NSO cells, heLa cells, BHK cells, HEK 293 cells or other human cells. Host cells may include single cells or cell populations.

The vector may be introduced into the host cell by conventional techniques well known to those skilled in the art. When the host is a prokaryote such as E.coli, competent cells, which can take up DNA, can be obtained after the exponential growth phase and then treated with CaCl ₂ The process is carried out using procedures well known in the art. Another approach is to use MgCl ₂ . Transformation can also be performed by electroporation, if desired. When the host is eukaryotic, the following DNA transfection methods may be used: calcium phosphate co-precipitation, conventional mechanical methods such as microinjection, electroporation, liposome encapsulation, etc.

The nanobodies of the invention may be used alone or in combination or coupling with a detectable label, a therapeutic agent, a PK (protein kinase) modifying moiety or a combination of any of the above.

Detectable labels include, but are not limited to: fluorescent or luminescent markers, radioactive markers, MRI (magnetic resonance imaging) or CT (electronic computer tomography) contrast agents, or enzymes capable of producing a detectable product. The preferred detectable label is a radionuclide.

Therapeutic agents that may be conjugated or coupled to an antibody of the invention include, but are not limited to: 1. a radionuclide; 2. biological toxicity; 3. a cytokine; 4. gold nanoparticles/nanorods; 5. a viral particle; 6. a liposome; 7. nano magnetic particles; 8. prodrug activating enzyme or biphenyl hydrolase-like protein (BPHL); 10. chemotherapeutic agents (e.g., cisplatin) or any form of nanoparticle, and the like.

Binding or coupling of the detectable label or therapeutic agent to the antibody can be performed by conventional methods well known to those skilled in the art. For example, the detectable label may be directly or indirectly bound to the nanobody, e.g., via a cleavable or non-cleavable linker peptide, or incorporated into the nanobody. The detectable label may be bound to the nanobody, in particular by substitution (e.g. by substituting H with I at the tyrosine residue level), by complexation or by chelation. For example, the therapeutic agent may be conjugated to the nanobody via a cleavable linker (e.g., a peptidyl, disulfide, or hydrazone linker).

In a preferred embodiment, the nanobody of the invention is conjugated with a radionuclide for use as a CDH17 specific molecular imaging probe, as described in more detail below.

CDH17 specific molecular imaging probe

In another aspect, the invention provides a CDH 17-specific molecular imaging probe comprising a radionuclide-labeled CDH 17-specific nanobody or CDH 17-specific nanobody fusion protein as described herein.

More specifically, a CDH 17-specific nanobody or CDH 17-specific nanobody fusion protein as described herein is labeled with a radionuclide via a bifunctional chelator.

As used herein, a bifunctional chelating agent is a class of chelating agents having both a metal chelating end and a protein anchoring end. The bifunctional chelating agent may be selected from NOTA, MAA-NOTA, p-SCN-Bn-Deferoxamine (DFO), p-SCN-NODA, MAA-GA-NODA, MAA-DOTA, DOTA-NHS, iEDTA or p-SCN-Bn-DTPA.

Preferably, the bifunctional chelating agent is selected from the group consisting of p-SCN-Bn-NOTA.

As used herein, the NOTA is 1,4, 7-triazacyclononane-1, 4, 7-triacetic acid;

the MAA-NOTA is (2, 2' - (7- (2- ((2- (2, 5-dioxo-2, 5-dihydro-1H-pyrrol-1-yl) ethyl) amino) -2-oxoethyl) -1,4, 7-triazacyclononane-1, 4-diyl) diacetic acid;

The p-SCN-Bn-NOTA is 2-S- (4-isothiocyanatophenyl) -1,4, 7-triazacyclononane-1, 4, 7-triacetic acid;

the p-SCN-Bn-Deferoxamine (DFO) is 1- (4-isothiocyanatophenyl) -3- [6, 17-dihydroxy-7,10,18,21-tetraoxo-27- (N-acetylhydroxyamino) -6,11,17,22-tetraazaheptyldisaccharide ] thiourea;

the p-SCN-NODA is 1,4, 7-triazacyclooctane-1, 4-diacetic acid-7-p-isothiocyanatobenzyl;

the MAA-GA-NODA is 2,2' - (7- (1-carboxy-4- ((2- (2, 5-dioxo-2, 5-dihydro-1H-pyrrol-1-yl) ethyl) amino) -4-oxobutyl) -1,4, 7-triazacyclononane-1, 4-diyl) diacetic acid;

the MAA-DOTA is 2,2' - (10- (1-carboxy-4- ((2- (2, 5-dioxo-2, 5-dihydro-1H-pyrrol-1-yl) ethyl) amino) -4-oxybutyl) -1,4,7, 10-triazacyclododecane-1, 4, 7-triyl) triacetic acid ];

the DOTA-NHS is 2,2' - (10- (2- ((2, 5-dioxopyrrolidin-1-yl) oxy) -2-oxoethyl) -1,4,7, 10-triazacyclododecane-1, 4, 7-triyl) triacetic acid;

the iEDTA is 1- (4-isothiocyanatobenzyl) ethylenediamine-N, N, N ', N' -tetraacetic acid;

the p-SCN-Bn-DTPA is 2- (4-isothiocyanatobenzyl) -diethylenetriamine pentaacetic acid.

More specifically, CDH 17-specific nanobodies as described herein are labeled with radionuclides via p-SCN-Bn-NOTA. More specifically, CDH 17-specific nanobody fusion proteins as described herein are labeled with a radionuclide via p-SCN-Bn-NOTA.

More specifically, the radionuclide is selected from Tc-99m, ga-68, F-18, I-123, I-125, I-131, I-124, in-111, ga-67, cu-64, zr-89, C-11, lu-177, re-188, Y-86, mn-52, sc-44, lu-177, Y-90, ac-225, at-211, bi-212, bi-213, cs-137, cr-51, co-60, dy-165, er-169, fm-255, au-198, ho-166, I-125, I-131, ir-192, fe-59, pb-212, mo-99, pd-103, P-32, K-42, re-186, re-188, sm-153, ra-223, ru-106, na-24, sr-89, tb-149, th-227, xe-133, yb-169 or Yb-177.

More specifically, the radionuclide is selected from Ga-68.

More specifically, CDH 17-specific nanobodies as described herein are labeled with Ga-68 (examples of one such CDH 17-specific molecular imaging probe are described in the examples ⁶⁸ Ga]Ga-NOTA-CDH1 or [ ⁶⁸ Ga]Ga-NOTA-CDH 2). More specifically, CDH 17-specific nanobody fusion proteins as described herein are labeled with Ga-68 (one example of such a CDH 17-specific molecular imaging probe is as followsDescribed in the examples [ ⁶⁸ Ga]Ga-NOTAN-aCDH17.1 or [ ⁶⁸ Ga]Ga-NOTA-ACDH17.2)。

In another aspect, the invention also provides a method of preparing a CDH 17-specific molecular imaging probe comprising modifying a CDH 17-specific nanobody or CDH 17-specific nanobody fusion protein as described herein by a bifunctional chelator to obtain a radionuclide-labeled intermediate; and labeling the radionuclide labeling intermediate with a radionuclide to obtain the CDH17 specific molecular imaging probe.

Composition and method for producing the same

In another aspect, the invention provides a composition comprising a CDH17 specific nanobody, CDH17 specific nanobody fusion protein, polynucleotide, vector, host cell, or molecular imaging probe as described herein. The compositions are useful for visualizing the expression of CDH17, diagnosing CDH 17-related tumors, predicting the progression and prognosis of CDH 17-related tumors, predicting the therapeutic effect of CDH 17-related tumors, and/or treating CDH 17-related tumors.

In some embodiments, the composition may be a pharmaceutical composition.

In some embodiments, the pharmaceutical composition may further comprise a pharmaceutically acceptable carrier and/or excipient.

In some embodiments, the pharmaceutical composition may further comprise an additional pharmaceutically active agent.

In some embodiments, the additional pharmaceutically active agent is an anti-inflammatory drug or an immunosuppressant.

In some embodiments, in the pharmaceutical composition, the CDH 17-specific nanobody, CDH 17-specific nanobody fusion protein, polynucleotide, vector, host cell, or molecular imaging probe as described herein, and the additional pharmaceutically active agent may be provided as separate components or as a mixed component. Thus, a CDH 17-specific nanobody, CDH 17-specific nanobody fusion protein, polynucleotide, vector, host cell, or molecular imaging probe as described herein and the additional pharmaceutically active agent can be administered simultaneously, separately or sequentially.

In some embodiments, the pharmaceutically acceptable carrier and/or excipient may comprise a sterile injectable liquid (e.g., an aqueous or non-aqueous suspension or solution). In certain exemplary embodiments, such sterile injectable liquids are selected from the group consisting of water for injection (WFI), bacteriostatic water for injection (BWFI), sodium chloride solutions (e.g., 0.9% (w/v) NaCl), dextrose solutions (e.g., 5% dextrose), surfactant-containing solutions (e.g., 0.01% polysorbate 20), pH buffered solutions (e.g., phosphate buffered solutions), ringer's solution, and any combination thereof.

The pharmaceutical compositions of the invention may include a "therapeutically effective amount" or a "prophylactically effective amount" of a CDH17 specific nanobody, CDH17 specific nanobody fusion protein, polynucleotide, vector, host cell, or molecular imaging probe as described herein. "prophylactically effective amount" means an amount sufficient to prevent, arrest or delay the onset of a disease. By "therapeutically effective amount" is meant an amount sufficient to cure or at least partially arrest the disease and its complications in a patient already suffering from the disease. The therapeutically effective amount may vary depending on the factors: the severity of the disease to be treated, the general state of the patient's own immune system, the general condition of the patient such as age, weight and sex, the mode of administration of the drug, and other treatments administered simultaneously, and the like.

Kit for detecting a substance in a sample

The invention also provides a kit comprising a CDH17 specific nanobody, a CDH17 specific nanobody fusion protein, a polynucleotide, a vector, a host cell, or a molecular imaging probe as described herein.

The kit can be used for visualizing the expression of CDH17, diagnosing CDH 17-related tumors, predicting the progress and prognosis of CDH 17-related tumors, predicting the therapeutic effect of CDH 17-related tumors and/or treating CDH 17-related tumors.

The kit may further comprise further containers, instructions for use, and other reagents and buffers required for the actual application, such as lysis media for lysing the sample, various buffers, detection labels, detection substrates, etc.

Diagnostic and therapeutic applications

The CDH17 specific nano antibody has extremely high affinity to CDH17, so that the nano antibody can be used for visualizing the expression of CDH17, diagnosing CDH 17-related tumors, predicting the progress and prognosis of CDH 17-related tumors, predicting the treatment effect of CDH 17-related tumors and/or treating CDH 17-related tumors.

Particularly, the CDH17 specific molecular image probe prepared by the CDH17 specific nano antibody has the characteristics of obviously improved affinity, obviously reduced non-specific uptake of normal tissue uptake and obviously improved image quality, and can be used for noninvasively, accurately and efficiently detecting the expression of human CDH17, so that the CDH17 specific molecular image probe is particularly suitable for diagnosing CDH 17-related tumors and predicting the therapeutic effect of CDH 17-related tumors. After proper radionuclides are selected for coupling, the method can also be used for accurately treating CDH17 related tumors.

Thus, in another aspect, the invention also relates to the use of a CDH17 specific nanobody, a CDH17 specific nanobody fusion protein, a polynucleotide, a vector, a host cell or a molecular imaging probe as described herein in the preparation of a kit or medicament for visualizing the expression of CDH17, diagnosing a CDH 17-related tumor, predicting the progression and prognosis of a CDH 17-related tumor, predicting the therapeutic effect of a CDH 17-related tumor and/or treating a CDH 17-related tumor.

As used herein, CDH 17-associated tumors may include various tumors or cancers well known in the art. For example, CDH 17-related tumors may include digestive tract tumors, such as gastric cancer, liver cancer, small intestine cancer, colorectal cancer, large intestine cancer, pancreatic cancer, esophageal cancer, and the like.

The beneficial effects of the invention are that

The invention discloses a CDH17 specific molecular image diagnosis and treatment integrated system, namely ⁶⁸ Ga]Ga-NOTA-CDH1、[ ⁶⁸ Ga]Ga-NOTA-CDH2、[ ⁶⁸ Ga]Ga-NOTA-aCDH17.1 and [ ⁶⁸ Ga]The Ga-NOTA-aCDH17.2 immune PET imaging probe realizes noninvasive visualization of human CDH17 molecule expression, and further realizes noninvasive diagnosis of colorectal cancer; the probe has the advantages of preparationSimple process, low cost, high specificity, high stability, short imaging period, low radiation dose, easy clinical transformation and the like; and screening patients with high CDH17 expression, and further developing CDH17 specific radioimmunotherapy, so as to realize target specific diagnosis and treatment integration of CDH17 expression positive tumors.

Drawings

FIG. 1 shows the results of SDS-PAGE determination of nanobody CDH1 and CDH2 expression.

FIG. 2 shows the results of SDS-PAGE determination of nanobody fusion proteins ACDH17.1 and ACDH 17.2.

FIG. 3 shows the results of immunohistochemical staining of CDH17 expression in human colorectal adenocarcinoma cell line CACO 2.

FIG. 4 shows the results of affinity assays of nanobody CDH1 and CDH2, nanobody fusion proteins ACDH17.1 and ACDH17.2 with human CDH17.

FIG. 5 shows the results of affinity assays of nanobody fusion proteins ACDH17.1 and ACDH17.2 with human serum albumin and mouse serum albumin.

FIG. 6 shows a CDH 17-specific molecular imaging probe of the invention [ ⁶⁸ Ga]Ga-NOTA-CDH1、[ ⁶⁸ Ga]Ga-NOTA-CDH2、[ ⁶⁸ Ga]Ga-NOTAN-aCDH17.1 [ ⁶⁸ Ga]Radiochemical purity assay of Ga-NOTAN-aCDH17.2.

FIG. 7 shows [ [ ⁶⁸ Ga]Experimental results of Ga-NOTA-CDH1 immunopet imaging for diagnosis of colorectal cancer.

FIG. 8 shows [ sic ] ⁶⁸ Ga]Experimental results of Ga-NOTA-CDH2 immunopet imaging for diagnosis of colorectal cancer.

FIG. 9 shows [ sic ] ⁶⁸ Ga]Ga-NOTA-aCDH17.1 and [ ⁶⁸ Ga]Multi-time point PET/CT imaging results of Ga-NOTA-Acdh17.2 in the CACO2 colorectal adenocarcinoma model.

FIG. 10 shows [ sic ] ⁶⁸ Ga]Ga-NOTA-aCDH17.1 and [ ⁶⁸ Ga]ROI results in PET/CT imaging of Ga-NOTA-aCDH17.2 in CACO2 colorectal adenocarcinoma model.

FIG. 11 shows [ sic ] ⁶⁸ Ga]Ga-NOTA-aCDH17.1 and [ ⁶⁸ Ga]Ga-NOTA-aCDH17.2 in CACO2 colorectalIn vitro distribution data map in PET/CT imaging of an adenocarcinoma model.

FIG. 12 compares [ ⁶⁸ Ga]Ga-NOTA-CDH1、[ ⁶⁸ Ga]Ga-NOTAN-aCDH17.1 [ ⁶⁸ Ga]ROI and in vitro biodistribution data of Ga-NOTA-aCDH17.2 probe in PET/CT imaging of colorectal adenocarcinoma model.

FIG. 13 shows the results of immunohistochemical staining to verify the expression of CDH17 inside tumors.

Detailed Description

The present invention is further illustrated below with reference to specific examples, which are not intended to limit the invention in any way. Unless specifically stated otherwise, the reagents, methods and apparatus employed in the present invention are those conventional in the art.

Example 1: preparation of CDH17 specific nano antibody and fusion protein thereof

According to the method previously published by the inventors (refer to patent No. ZL202011131233.7 entitled "molecular imaging probe for diagnosing multiple myeloma", which is incorporated herein by reference in its entirety), the gene sequences of novel CDH 17-specific monovalent nanobodies CDH1 (SEQ ID No. 5), CDH2 (SEQ ID No. 10), nanobody fusion proteins ACDH17.1 (SEQ ID No. 14) and ACDH17.2 (SEQ ID No. 16) were cloned into pET-30a (+) expression vectors and expressed recombinantly in escherichia coli (e.coli), respectively.

The results of SDS-PAGE determination of nanobody CDH1 and CDH2 expression are shown in FIG. 1; the results of SDS-PAGE determination of nanobody fusion proteins ACDH17.1 and ACDH17.2 are shown in FIG. 2.

Example 2: establishing CDH17 expression positive tumor-bearing mouse model

The human colorectal adenocarcinoma cell line CACO2 CDH17 was found to be positive for expression and the human colorectal adenocarcinoma cell line LS174T CDH17 was found to be negative for expression by immunohistochemical staining using an anti-human CDH17 monoclonal antibody (Santa Cruz Biotechnology, sc-393533) as primary antibody, as shown in FIG. 3. Respectively 1×10 ⁶ CACO2 and LS174T cells were inoculated into the right shoulder of NCG (NOD-Prkdcem 26Cd52IL2rgem26Cd 22/Nju) mice to establish a model of subcutaneous colorectal adenocarcinoma cell line transplantation tumor.

Example 3: affinity of CDH17 specific nanobody and fusion protein thereof

The affinity measurement results of the nanobodies CDH1 and CDH2 and human CDH17 are shown in FIG. 4, K _D Values were 1.024nM and 181.6nM, respectively; the affinity measurement results of the nanobody fusion proteins ACDH17.1 and ACDH17.2 and human CDH17 are shown in FIG. 4, K _D Values 71.49nM and 181.0nM, respectively; the affinity measurement of the nanobody fusion protein ACDH17.1 and human serum albumin and mouse serum albumin is shown in figure 5, K _D Values of 120.9pM and 443.4pM, respectively; the affinity measurement of the nanobody fusion protein ACDH17.2 with human serum albumin and mouse serum albumin is shown in figure 5, and the nanobody fusion protein ACDH17.2 does not bind with human serum albumin and binds with mouse serum albumin to K _D The value was 3.185nM.

Example 4: preparation of CDH17 specific molecular imaging probe

preparation of p-SCN-Bn-NOTA modified CDH1, CDH2, ACDH17.1 and ACDH17.2 intermediates NOTA-CDH1, NOTA-CDH2, NOTA-aCDH17.1 and NOTA-aCDH17.2. The method comprises the following specific steps: 1mg of CDH1, CDH2, ACDH17.1 or ACDH17.2 were dissolved in 1mL of Phosphate Buffer (PBS), 0.1mL of 0.1M sodium carbonate (Na ₂ CO ₃ Ph=11.4) buffer solution the nanobody solution PH was adjusted to 9.0-10, the reaction system volume was 1.1mL. p-SCN-Bn-NOTA (CAS Number:170597-66-8; macromolecules) freshly dissolved in dimethyl sulfoxide (DMSO) was added to the nanobody solution in a molar ratio of p-SCN-Bn-NOTA to nanobody=10:1. The reaction system is placed at room temperature for reaction for 2 hours, PBS is taken as a mobile phase, a pre-balanced PD-10 desalting column (GE Healthcare) is used for purifying the nanometer antibodies modified by NOTA, and NOTA-CDH1, NOTA-CDH2, NOTA-aCDH17.1 and NOTA-aCDH17.2 are collected; concentrating with ultrafiltration tube (Merck Millipore) with cutoff value of 10kDa, measuring NOTA-CDH1, NOTA-CDH2, NOTA-aCDH17.1 and NOTA-aCDH17.2 with NanoDrop, and packaging at-20deg.C.

⁶⁸ Ga-labeled NOTA-CDH1, NOTA-CDH2, NOTA-aCDH17.1 and NOTA-aCDH17.2 preparation [ [ ⁶⁸ Ga]Ga-NOTA-CDH1、[ ⁶⁸ Ga]Ga-NOTA-CDH2、[ ⁶⁸ Ga]Ga-NOTAN-aCDH17.1 [ ⁶⁸ Ga]Ga-NOTAN-aCDH17.2. The method comprises the following steps of: germanium gallium generator (Eckert) was rinsed with 4mL of 0.05M hydrochloric acid solution (HCl)&Ziegler Radiopharma Inc), and collecting equivalent volume activity of about 370-555MBq ⁶⁸ Ga leaches; middle section with highest activity ⁶⁸ Ga leacheate 2mL, added with 0.1mL 1M sodium acetate solution (NaoAc) to regulate ⁶⁸ The pH value of the Ga leacheate is 4.0-4.5; the coupling standby NOTA-CDH1, NOTA-CDH2, NOTA-aCDH17.1 and NOTA-aCDH17.2 mug are added ⁶⁸ Ga leacheate, reaction system volume<2.5mL; placing the reaction system in a constant temperature oscillator to react for 5-10 minutes at room temperature; after the labeling reaction, PBS was used as a mobile phase, and the pre-equilibrated PD-10 desalting column was used again to separate the free phase ⁶⁸ Ga. Purifying the final product; determination of unattenuated corrected radiochemical yield (Radiochemical yield, RCY)>50％。

[ ⁶⁸ Ga]Ga-NOTA-CDH1、[ ⁶⁸ Ga]Ga-NOTA-CDH2、[ ⁶⁸ Ga]Ga-NOTAN-aCDH17.1 [ ⁶⁸ Ga]Ga-NOTA-aCDH17.2 quality control. Suction 10 mu L [ ⁶⁸ Ga]Ga-NOTA-CDH1、[ ⁶⁸ Ga]Ga-NOTA-CDH2、[ ⁶⁸ Ga]Ga-NOTAN-aCDH17.1 [ ⁶⁸ Ga]Ga-NOTA-aCDH17.2 was spotted on a silica gel plate, using a 0.1M sodium citrate solution (pH=5) as a mobile phase, and using a radioactive thin layer chromatograph (Radio-TLC, eckert&Ziegler Radiopharma Inc) the radiochemical purity of the probe was determined (Radiochemical purity, RCP). Freshly prepared [ as shown in FIG. 6 ] ⁶⁸ Ga]Ga-NOTA-CDH1、[ ⁶⁸ Ga]Ga-NOTA-CDH2、[ ⁶⁸ Ga]Ga-NOTAN-aCDH17.1 [ ⁶⁸ Ga]Ga-NOTA-aCDH17.2 RCP is more than 99 percent.

Example 5: CDH17 specific molecular image probe immune PET imaging diagnosis colorectal cancer based on CDH17 specific nano antibody

[ ⁶⁸ Ga]Ga-NOTA-CDH1 [ ⁶⁸ Ga]The experimental results of Ga-NOTA-CDH2 immune PET imaging diagnosis of colorectal cancer are shown in FIG. 7 and FIG. 8. The method comprises the following steps: the PET/CT imaging acquisitions of the animals involved in this study were all done using an IRIS small animal PET/CT scanner (Inviscan Imaging Systems). Each mouse was injected via the tail vein with 3.7-7.4MBq [ ⁶⁸ Ga]Ga-NOTA-CDH1 and [ ⁶⁸ Ga]Ga-NOTA-CDH2 (3 per group) was mixed with oxygen 1 hour after injectionThe mice were anesthetized with isoflurane (2% concentration) and placed in a supine position on a PET/CT scanner bed for subsequent acquisition of PET and CT images, and image reconstruction was accomplished with the IRIS system self-contained software, as shown in fig. 7 and 8. The radio uptake values of vital tissue organs were calculated in% ID/g (percent of injected dose per gram) units using an OsiriX Lite image processing workstation (Pixmeo SARL) to delineate regions of interest (Region of interest, ROI) of heart and major tissue organs (liver, lung, kidney, muscle) on reconstructed PET images. The left side of the two panels shows PET/CT images, the middle shows ROI images, and the right side shows in vitro biodistribution data images. Both sets of figures can see CDH 17-specific nanobody probes [ ⁶⁸ Ga]Ga-NOTA-CDH1 and [ ⁶⁸ Ga]Ga-NOTA-CDH2 has higher uptake in tumor tissues and higher nonspecific uptake in major excretory (kidney) and metabolic (liver) tissues. Analysis by delineating ROI [ ⁶⁸ Ga]Ga-NOTA-CDH1 and [ ⁶⁸ Ga]Distribution of Ga-NOTA-CDH2 in vivo, and in addition, in vitro biological distribution experimental results further reveal the distribution of probes in major tissues and organs in vivo. The above results indicate that [ ⁶⁸ Ga]Ga-NOTA-CDH1 and [ ⁶⁸ Ga]Ga-NOTA-CDH2 probes can non-invasively visualize CDH17 expression.

Example 6: CDH17 specific molecular imaging probe immune PET imaging diagnosis colorectal cancer based on CDH17 specific nano antibody fusion protein

[ ⁶⁸ Ga]Ga-NOTA-aCDH17.1 and [ ⁶⁸ Ga]Ga-NOTAN-aCDH17.2 immune PET imaging diagnosis colorectal cancer, the experimental result is shown in figure 9 [ ⁶⁸ Ga]Ga-NOTA-aCDH17.1 and [ ⁶⁸ Ga]Ga-NOTA-aCDH17.2 PET/CT imaging at multiple time points in the CACO2 colorectal adenocarcinoma model. CDH17 specific nanobody fusion protein probe ⁶⁸ Ga]Ga-NOTA-aCDH17.1 and [ ⁶⁸ Ga]Ga-NOTA-aCDH17.2 still has higher uptake in tumor tissues. As shown in the ROI data of fig. 10, uptake at the tumor site gradually increased over time over 4 hours. The in vitro distribution data shown in fig. 11 further demonstrates the enrichment of the probe at the tumor site. By further comparing [ [ ⁶⁸ Ga]Ga-NOTA-CDH1、[ ⁶⁸ Ga]Ga-NOTAN-aCDH17.1 [ ⁶⁸ Ga]ROI and in-vitro biodistribution data of two types of Ga-NOTA-aCDH17.2 probes in PET/CT imaging of colorectal adenocarcinoma model show that the nanobody fusion protein probes do not influence the capability of the nanobody fusion protein probes in noninvasive visualization of CDH17 in tumors, and experimental results are shown in figure 12. Furthermore, immunohistochemical staining of tumors with CDH 17-specific antibodies (Santa Cruz Biotechnology, sc-393533) confirmed the expression of CDH17 inside the tumors, as shown in FIG. 13.

It should be noted that the description of the present invention and the accompanying drawings illustrate preferred embodiments of the present invention, but the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, which are not to be construed as additional limitations of the invention, but are provided for a more thorough understanding of the present invention. The above-described features are further combined with each other to form various embodiments not listed above, and are considered to be the scope of the present invention described in the specification; further, modifications and variations of the present invention may be apparent to those skilled in the art in light of the foregoing teachings, and all such modifications and variations are intended to be included within the scope of this invention as defined in the appended claims.

Claims

1. A CDH 17-specific nanobody comprising:

(1) CDR1 having the amino acid sequence shown in SEQ ID No.1, CDR2 having the amino acid sequence shown in SEQ ID No.2 and CDR3 having the amino acid sequence shown in SEQ ID No.3, or

(2) CDR1 having the amino acid sequence shown in SEQ ID No.6, CDR2 having the amino acid sequence shown in SEQ ID No.7 and CDR3 having the amino acid sequence shown in SEQ ID No.8,

preferably, the CDH17 specific nanobody has the amino acid sequence shown in SEQ ID No.4 or 9.

2. A CDH 17-specific nanobody fusion protein comprising a nanobody according to claim 1 and an albumin binding domain,

preferably, the albumin binding domain has the amino acid sequence shown in SEQ ID No.11 or 12,

preferably, the CDH17 specific nanobody fusion protein has the amino acid sequence shown in SEQ ID No.13 or 15.

3. A polynucleotide encoding the CDH 17-specific nanobody according to claim 1 or the CDH 17-specific nanobody fusion protein according to claim 2,

preferably, the polynucleotide has the nucleotide sequence shown as SEQ ID No.5, 10, 14 or 16.

4. A vector comprising the polynucleotide of claim 3.

5. A host cell comprising the vector of claim 4.

6. A CDH17 specific molecular imaging probe comprising a radionuclide-labeled CDH17 specific nanobody according to claim 1 or a CDH17 specific nanobody fusion protein according to claim 2.

7. The molecular imaging probe of claim 6, wherein the CDH 17-specific nanobody according to claim 1 or the CDH 17-specific nanobody fusion protein according to claim 2 is labeled with a radionuclide via a bifunctional chelator,

preferably, the bifunctional chelating agent is selected from the group consisting of p-SCN-Bn-NOTA,

preferably, the radionuclide is selected from Tc-99m, ga-68, F-18, I-123, I-125, I-131, I-124, in-111, ga-67, cu-64, zr-89, C-11, lu-177, re-188, Y-86, mn-52, sc-44, lu-177, Y-90, ac-225, at-211, bi-212, bi-213, cs-137, cr-51, co-60, dy-165, er-169, fm-255, au-198, ho-166, I-125, I-131, ir-192, fe-59, pb-212, mo-99, pd-103, P-32, K-42, re-186, re-188, sm-153, ra-223, ru-106, na-24, sr-89, tb-149, th-227, xe-133, yb-169 or Yb-177,

Preferably, the radionuclide is selected from Ga-68.

8. A method for preparing a CDH 17-specific molecular imaging probe, comprising modifying the CDH 17-specific nanobody according to claim 1 or the CDH 17-specific nanobody fusion protein according to claim 2 with a bifunctional chelating agent to obtain a radionuclide-labeled intermediate; and labeling the radionuclide labeling intermediate with a radionuclide to obtain a CDH17 specific molecular imaging probe,

preferably, the radionuclide is selected from Ga-68.

9. A kit or composition for visualizing the expression of CDH17, diagnosing a CDH 17-related tumor, predicting the progression and prognosis of a CDH 17-related tumor, predicting the therapeutic effect of a CDH 17-related tumor and/or treating a CDH 17-related tumor, characterized by comprising a CDH 17-specific nanobody according to claim 1, a CDH 17-specific nanobody fusion protein according to claim 2, a polynucleotide according to claim 3, a vector according to claim 4, a host cell according to claim 5 or a molecular imaging probe according to any of claims 6-8.

10. Use of a CDH 17-specific nanobody according to claim 1, a CDH 17-specific nanobody fusion protein according to claim 2, a polynucleotide according to claim 3, a vector according to claim 4, a host cell according to claim 5 or a molecular imaging probe according to any of claims 6-8 for the preparation of a kit or medicament for visualizing the expression of CDH17, diagnosing a CDH 17-related tumor, predicting the progression and prognosis of a CDH 17-related tumor, predicting the therapeutic effect of a CDH 17-related tumor and/or treating a CDH 17-related tumor.