CN116333128A

CN116333128A - Nanometer antibody targeting human LILRB2 and application thereof

Info

Publication number: CN116333128A
Application number: CN202211072444.7A
Authority: CN
Inventors: 焦莎莎; 王荣娟; 毛冠凡; 张畅; 王双; 张锦超
Original assignee: Beijing Konuoxincheng Technology Co ltd
Current assignee: Beijing Konuoxincheng Technology Co ltd
Priority date: 2022-06-28
Filing date: 2022-06-28
Publication date: 2023-06-27
Also published as: CN114805580B; CN116333127A; CN114805580A

Abstract

The invention discloses an anti-LILRB 2 nanobody, nucleic acid for encoding the nanobody, an expression vector containing the nucleic acid, a pharmaceutical composition containing the nanobody and application of the nanobody in preparation of medicines.

Description

Nanometer antibody targeting human LILRB2 and application thereof

Technical Field

The invention belongs to the field of antibody engineering, and particularly relates to a therapeutic single domain antibody for diagnosing or treating tumors, in particular to an anti-LILRB 2 nano antibody, a derivative protein thereof and application of the anti-LILRB 2 nano antibody in preparation of medicines.

Background

Nanobodies are the smallest antibody molecules at present, originally found in camel blood by belgium scientists Hamers, a class of interest in engineering antibody products. The nano antibody has the main advantages that: firstly, the volume is 1/10 of that of the common antibody, because the volume is small, the penetration of the common antibody in animal tissues is strong, for example, the common antibody can reach the inside of a high-density tumor through brain tissues of a human body, but the common antibody cannot, so that certain tumors or brain diseases can be treated by the nano antibody; secondly, the antigen specificity is good; thirdly, the gene modification is easy, and the artificial modification is convenient to obtain antibodies against different pathogens; fourth, the stability is high, for example, the time that the nano antibody is not naturally decomposed in the body is longer than that of the common antibody (meaning that the drug effect time is longer lasting), and the nano antibody can pass through the human stomach to keep the effectiveness.

LILRB2, also known as ILT4, is expressed mainly on myeloid cells, including monocytes, dendritic cells, macrophages and neutrophils. Genetic studies have shown that Tumor Associated Macrophages (TAMs) in a variety of tumor microenvironments highly express LILRB2, inhibiting LILRB2 (the corresponding protein in mice called Pirb) reduces invasion of tregs and MDSCs in tumor tissues. Animal experiments show that Pirb antibodies inhibit tumor growth and have synergistic effect with PD-1 antibodies. LILRB2 is mainly expressed in bone marrow cells, with limited expression in other tissues, which makes on-target, off-tissue less toxic. Human LILRB2 is an important steady-state surface regulator in the process of myelocyte maturation, is a promising myeloimmune checkpoint target which is specially determined for the myelocyte function, and has important therapeutic value.

Disclosure of Invention

The ScFv, fab or whole IgG type anti-LILRB 2 antibody molecules in the prior art have complex structure and larger molecules, and can connect active molecules to LILRB2, but have complex functions and methods affecting the active molecules and lower loading efficiency; the nanometer antibody molecule is small and easy to operate, but has low humanization degree, low affinity and half-life prolonging performance to be further improved.

In order to overcome the defects in the prior art, the invention provides a series of anti-LILRB 2 nanometer antibody sequences and a preparation scheme.

In a first aspect, the invention provides a nanobody against LILRB2, according to an embodiment of the invention, which nanobody is capable of specifically binding to LILRB2, and the complementarity determining regions CDRs of the VHH strand in the nanobody are one or more selected from the group consisting of:

(1) SEQ ID NO:9, CDR1, SEQ ID NO:10, and CDR2 as set forth in SEQ ID NO:11, CDR3;

(2) SEQ ID NO:12, CDR1, SEQ ID NO:13, and CDR2 as set forth in SEQ ID NO:14, CDR3;

(3) SEQ ID NO:15, CDR1, SEQ ID NO:16, and CDR2 as set forth in SEQ ID NO:17, CDR3;

(4) SEQ ID NO:18, CDR1, SEQ ID NO:19, and CDR2 as set forth in SEQ ID NO:20, CDR3 shown in fig;

(5) SEQ ID NO:21, CDR1, SEQ ID NO:22, and CDR2 as set forth in SEQ ID NO:23, CDR3.

Further, in some embodiments of the invention, the nanobody described above is a humanized VHH or a camelized VHH.

Further, in some embodiments of the invention, the nanobody described above has a sequence as set forth in SEQ ID NO: 3. 4, 5, 6, 7, or an amino acid sequence as set forth in any one of SEQ ID NOs: 3. 4, 5, 6, 7, and an amino acid sequence having at least 80% identity.

"at least 80% identity" as used herein is, for example, any percent identity of ≡80% such as at least 80%, preferably at least 85%, more preferably at least 90%, even more preferably at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or even 100% identity.

In a second aspect, the present invention provides a fusion protein comprising a functional domain capable of specifically binding to LILRB2, said functional domain consisting of an anti-LILRB 2 nanobody as described in any one of the above.

The nano antibody provided by the invention can be fused with any other protein or substance to achieve different purposes, for example, can be combined with fluorescent protein, enzyme or radioactive element to achieve the purpose of easy detection, and can be fused with a drug molecule for treating LILRB2 mediated related diseases to achieve the purpose of better treatment. The type of protein fused to the nanobody can be appropriately selected by those skilled in the art according to actual needs or purposes, and it is also within the scope of the present invention regardless of the type of fusion of the substance.

In a third aspect, the present invention provides an anti-LILRB 2 antibody, according to an embodiment of the present invention, which is a conventional antibody or a functional fragment thereof, the heavy chain variable region of which is composed of the anti-LILRB 2 nanobody of any one of the preceding claims;

further, the above functional fragment is a Fab, fab ', (Fab') 2, fv, scFv or sdFv structure of the conventional antibody.

Traditional antibodies are structurally composed of two identical heavy chains and two identical light chains, a light chain having a light chain variable region (VL) and a light chain constant region (CL); the heavy chain has a heavy chain variable region (VH) and a heavy chain constant region (CH 1, CH2, CH3 and/or CH 4). On the premise that the present invention discloses a structure with a nanobody capable of specifically binding to LILRB2, a person skilled in the art can easily think of using the nanobody of the present invention to modify a conventional antibody, for example, applying the CDR region structure of the nanobody of the present invention to a conventional antibody to obtain a conventional antibody capable of specifically binding to LILRB2, and such conventional antibody also falls into the scope of protection of the present invention; further, based on the structure of the conventional antibody, part of the structure such as Fab, fab ', (Fab') 2, fv, scFv or sdFv structure, etc. is also LILRB2 binding specific, which is also within the scope of the present invention.

In a fourth aspect, the invention provides a composition for treating a disease comprising a nanobody as described above against LILRB2, a fusion protein as described above or an antibody as described above, and a pharmaceutically acceptable adjuvant.

The pharmaceutical compositions provided herein contain at least one (e.g., one, two, three, or four) of the antibodies or antigen-binding fragments described in the examples of the invention, and two or more (e.g., two, three, or four) of any of the antibodies or antigen-binding fragments described herein can be present in any combination in the pharmaceutical composition. The pharmaceutical composition may be formulated in any manner known in the art.

The pharmaceutical composition may also contain a pharmaceutically acceptable carrier. As used herein, "pharmaceutically acceptable carrier" includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like that are physiologically compatible. Examples of pharmaceutically acceptable carriers include one or more of water, saline, phosphate buffered saline, dextrose, glycerol, ethanol, and the like, and combinations thereof. In many cases, it is preferred to include an isotonic agent, for example, a sugar, a polyalcohol such as mannitol, sorbitol, or sodium chloride in the composition. The pharmaceutically acceptable carrier may further comprise minor amounts of auxiliary substances, such as wetting or emulsifying agents, preservatives or buffers, which increase the shelf life or efficacy of the antibody.

The dosage form of the medicine provided by the invention is not strictly limited, can be prepared into various dosage forms according to the existing methods in the field of medicines, and is applied to patients needing treatment by oral administration, nasal inhalation, rectum, parenteral administration or transdermal administration and the like.

In a fifth aspect, the invention provides an isolated nucleic acid molecule encoding a nanobody as defined in any of the above.

Based on the present disclosure, a person skilled in the art can easily obtain polynucleotide molecules encoding the nanobody and the fusion protein described above by conventional techniques in the art, and based on the degeneracy of codons, the polynucleotide molecules are variable, and there are various possibilities of specific base sequences thereof, based on which, no matter how the polynucleotide molecules are varied, as long as they can encode the nanobody or the fusion protein of the present invention, thus falling within the scope of the present invention.

In a sixth aspect, the invention provides a vector comprising a nucleic acid molecule as described above.

In a seventh aspect, the invention provides a recombinant cell comprising a vector as described above.

Embodiments of the invention provide recombinant vectors (e.g., expression vectors) comprising the isolated polynucleotides disclosed herein (e.g., polynucleotides encoding the polypeptides disclosed herein), host cells into which the recombinant vectors are introduced (i.e., such that the host cells contain the polynucleotides and/or the polynucleotide-containing vectors), and recombinant antibody polypeptides or fragments thereof produced by recombinant techniques.

As used herein, a "vector" is any construct capable of delivering one or more polynucleotides of interest to a host cell when the vector is introduced into the host cell. An "expression vector" is capable of delivering and expressing one or more polynucleotides of interest as encoded polypeptides in a host cell into which the expression vector has been introduced. Thus, in an expression vector, a polynucleotide of interest is localized for expression in the vector by being operably linked to regulatory elements such as promoters, enhancers and/or polyadenylation tails, located at or near or flanking the integration site of the polynucleotide of interest in the vector or in the genome of the host cell, such that the polynucleotide of interest will be translated in the host cell into which the expression vector is introduced.

The vector may be introduced into the host cell by methods known in the art, such as electroporation, chemical transfection (e.g., DEAE-dextran), transformation, transfection, and infection and/or transduction (e.g., with recombinant virus). Thus, non-limiting examples of vectors include viral vectors (useful for producing recombinant viruses), naked DNA or RNA, plasmids, cosmids, phage vectors, and DNA or RNA expression vectors associated with cationic condensing agents.

Embodiments of the invention provide host cells transformed with the vectors described above. The host cell may be a prokaryotic or eukaryotic cell. A preferred prokaryotic host cell is E.coli (Escherichia coli). Preferably, the eukaryotic cell is selected from: primordial biological cells, animal cells, plant cells, and fungal cells. More preferably, the host cell is a mammalian cell, including but not limited to CHO and COS cells. A preferred fungal cell is Saccharomyces cerevisiae.

In an eighth aspect, the present invention provides a method of preparing a nanobody as defined in any of the above, comprising: culturing the recombinant cells as described above, and separating and purifying the culture product to obtain the nanobody.

It should be noted that, the preparation of the nanobody, the fusion protein and the antibody of the invention may be achieved by chemical synthesis, genetic engineering techniques, or other methods, and the preparation of the nanobody, the fusion protein or the antibody of the invention is within the scope of the invention.

In a ninth aspect, there is provided the use of an anti-LILRB 2 nanobody, fusion protein as described above, antibody as described above, composition as described above, nucleic acid molecule as described above, vector as described above, or recombinant cell as described above according to any one of the above for preventing, treating and/or ameliorating a solid tumor or hematological tumor.

Preferably, the solid tumor is lung cancer, non-small cell lung cancer, pancreatic ductal carcinoma, chronic lymphocytic leukemia, acute myelogenous leukemia, endometrial cancer, hepatocellular carcinoma, melanoma, ovarian cancer, breast cancer, colorectal cancer, glioma, gastric cancer, renal cancer, testicular cancer, esophageal cancer, cervical cancer, bulb lung cancer, leukemia, thyroid cancer, liver cancer, cancer of the urinary tract, or cancer of the head and neck.

For a better understanding of the invention, some terms are first defined. Other definitions are set forth throughout the detailed description.

In general, the antigen binding properties of antibodies can be described by 3 specific regions located in the variable region of the heavy chain, called variable regions (CDRs), which are separated into 4 Framework Regions (FRs), the amino acid sequences of the 4 FRs being relatively conserved and not directly involved in the binding reaction. These CDRs form a loop structure, the β -sheets formed by the FR therebetween are spatially close to each other, and the CDRs on the heavy chain and the CDRs on the corresponding light chain constitute the antigen binding site of the antibody. It is possible to determine which amino acids constitute the FR or CDR regions by comparing the amino acid sequences of the same type of antibody.

The invention includes not only whole antibodies but also fragments of antibodies having immunological activity or fusion proteins of antibodies with other sequences. Thus, the invention also includes fragments, derivatives and analogues of said antibodies.

"chimeric antibody" refers to an antibody in which the amino acid sequence of an immunoglobulin molecule is derived from two or more species. Typically, the variable regions of both the light and heavy chains correspond to variable regions of an antibody of desired specificity, affinity and capacity derived from one mammalian species (e.g., mouse, rat, rabbit, etc.), while the constant regions are homologous to sequences in the antibody derived from another species (typically human) to avoid eliciting an immune response in that species.

"nanobodies" are generally as defined in WO 2008/020079 or WO 2009/138519 and in one particular aspect generally represent VHHs, humanized VHHs or camelized VH (such as camelized human VH), or generally represent sequence optimized VHHs (e.g. optimized for chemical stability and/or solubility, maximum overlap with known human framework regions and maximum expression). The "nanobody" is obtained by genetic engineering methods, mainly of 3 classes, the first class being the heavy chain variable region obtained from camelid hcabs, being a single folding unit, retaining the complete antigen binding activity, being the smallest fragment of the natural antibody. The second is the heavy chain variable region obtained from cartilage fish IgNAR such as shark, and is denoted by VNAR. The third class is heavy or light chain variable regions obtained from human or murine monoclonal antibodies, retaining antigen binding activity, but with greatly reduced affinity and solubility.

"Fc region" or "Fc" refers to the C-terminal region of an immunoglobulin heavy chain that contains at least a portion of the hinge region, the CH2 domain, and the CH3 domain, which mediate binding of the immunoglobulin to host tissues or factors, including binding to Fc receptors located on various cells of the immune system (e.g., effector cells) or to a first component of the classical complement system (e.g., C1 q), including native sequence Fc regions and variant Fc regions. Typically, the human IgG heavy chain Fc region is a segment from the amino acid residue at its Cys226 or Pro230 position to the carboxy terminus, but its boundaries may vary. The C-terminal lysine (residue 447, according to the EU numbering system) of the Fc region may or may not be present. Fc may also refer to this region of isolation, or in the case of a protein polypeptide comprising Fc, for example a "binding protein comprising an Fc region", also referred to as an "Fc fusion protein" (e.g., an antibody or immunoadhesin). The Fc region of the natural sequences in the antibodies of the present invention includes human IgG1, igG2 (IgG 2A, igG 2B), igG3 and IgG4. In IgG, igA, and IgD antibody isotypes, the Fc region comprises CH2 and CH3 constant domains of each of the two heavy chains of the antibody; igM and IgEFc regions comprise three heavy chain constant domains (CH domains 2-4) in each polypeptide chain.

"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 term "immunological binding" refers to a specific binding reaction that occurs between an antibody molecule and an antigen for which the antibody is specific. The intensity or affinity of an immunological binding interaction may be expressed in terms of the equilibrium dissociation constant (KD) of the interaction, where a smaller KD value indicates a higher affinity. The immunological binding properties between the two molecules can be quantified using methods well known in the art. One method involves measuring the rate of antigen binding site/antigen complex formation and dissociation. Both the "binding rate constant" (Ka or Kon) and the "dissociation rate constant" (Kd or Koff) referring to a particular antibody-antigen interaction can be calculated from the concentration and the actual rate of association and dissociation, and the KD, ka and Kd values can be measured by any effective method. In a preferred embodiment, the dissociation constant is measured using bioluminescence interferometry. In other preferred embodiments, the dissociation constant can be measured using surface plasmon resonance techniques (e.g., biacore) or KinExa.

"vector" refers to a nucleic acid molecule capable of transporting another nucleic acid to which it is linked. One type of vector is a "plasmid," which refers to a circular double stranded DNA loop into which additional DNA segments may be ligated. Another type of vector is a viral vector, in which additional DNA segments may be ligated into the viral genome. Some vectors are capable of autonomous replication in a host cell into which they are introduced (e.g., bacterial vectors having a bacterial origin of replication and an episomal mammalian vector). Other vectors (e.g., non-episomal mammalian vectors) can be integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome. In addition, certain vectors are capable of directing the expression of genes to which they are operatively linked.

"nucleic acid molecule" is intended to include DNA molecules and RNA molecules. The nucleic acid molecule may be single-stranded or double-stranded, and may be cDNA.

The invention has the following beneficial technical effects:

the anti-LILRB 2 nanobody can be combined with human LILRB2 with high affinity, and has potential therapeutic value on tumors.

Drawings

FIG. 1 shows ELISA detection of binding of anti-LILRB 2 chimeric antibodies to recombinant human LILRB2 protein;

FIG. 2 shows FACS detection of binding activity of anti-LILRB 2 chimeric antibodies on human LILRB2/293 cells;

FIG. 3 shows FACS detection of binding activity of anti-LILRB 2 chimeric antibodies on cyno LILRB2/293 cells.

Detailed Description

The scheme of the present invention will be explained below with reference to examples. It will be appreciated by those skilled in the art that the following examples are illustrative only and are not to be construed as limiting the invention. The experimental methods in the following examples are conventional methods unless otherwise specified. The raw materials, reagent materials and the like used in the examples described below are commercially available products unless otherwise specified.

Example 1: construction of camel nanobody immune phage library

The antigen is utilized to immunize camels, peripheral Blood Mononuclear Cells (PBMC) are separated, total RNA is extracted for reverse transcription, a reverse transcription product is taken as a template to amplify a heavy chain variable region (variable domain of the heavy-chain of heavy chain antibody, VHH) of the nanometer antibody and is connected with a phage display vector, and the antigen is electrically transferred into competent cells of escherichia coli TG1 to construct the camel immune library.

Specifically, camels were immunized once for two weeks for 4 times. Each injection of 0.8mg of human LILRB2 extracellular recombinant protein was adjuvanted with Freund's complete/incomplete adjuvant (Sigma, F5881, F5506) by subcutaneous multipoint injection. Serum was isolated from 1mL of blood 2 weeks after each immunization, and titers of whole antibodies (IgG) and heavy chain antibodies (heavy chain antibody, hcAb) in the serum were determined by ELISA using the immunogen as a measurement antigen. When the serum titer reaches the requirement of stock establishment, 100mL of camel peripheral blood is collected, PBMC are separated by using a separation kit (Tianjin ocean, cat: TBD2011 CM), and total RNA of the PBMC is extracted and inverted to obtain cDNA which is used as a template for the subsequent amplification of VHH fragments. And (3) according to the related literature and database, searching the gene of the camel source VHH antibody, designing and synthesizing a VHH antibody library construction primer, and amplifying the gene sequence of the antibody variable region by PCR. The vector and amplified antibody fragments are then digested with endonucleases. The connection product is constructed by adopting a connection mode of T4 ligase, and is transferred into the TG1 strain by utilizing the electrotransfection technology. Finally construct a 1.8X10 ⁸ A camel anti-human LILRB2 VHH antibody immune library for use in the screening of specific anti-human LILRB2 nanobodies. To test the library for correct rate, 50 clones were randomly selected for colony PCR, which showed 90% insertion rate.

And screening the constructed camel immune library by a solid phase screening method to obtain the specific phage display nano antibody. 5 phage-displayed nanobodies that bind to the recombinant protein of human LILRB2 were obtained by primitive library presentation, screening and identification: a2, C3, C9, D9 and E2.

Example 2: preparation of anti-human LILRB2 nanobody and control antibody

The heavy and light chain variable region sequences of the same target point reference antibody MK-4830 (sequence sources: CN110719917A, SEQ ID NO.2 and 7) are shown as SEQ ID NO.1 and SEQ ID NO.2, the light and heavy chain sequences are cloned into eukaryotic transient expression vectors containing a human lambda/IgG4 light and heavy chain constant region respectively to obtain reference antibody MK-4830 light chain and heavy chain expression plasmids, the reference antibody MK-4830 light chain and heavy chain expression plasmids are transferred into escherichia coli for amplification, a large number of plasmids containing the reference antibody light chain and heavy chain are obtained by separation, ethanol precipitation is carried out on the plasmids, and the light and heavy chain plasmids of the reference antibody are transferred into HEK293 cells for recombinant expression according to the operation instruction of transfection reagent 293fectin (Cat: 12347019, gibco). And 5-6 days after cell transfection, taking a culture supernatant, and purifying the expression supernatant by using a ProA affinity chromatography column to obtain a control antibody.

According to the sequencing result of the phage displayed nano antibody, designing a primer, cloning the primer into a eukaryotic transient expression vector containing a human Fc (hFc) coding gene by a PCR method, and carrying out recombinant expression in HEK293 cells. After 5-6 days of cell transfection, the culture supernatant is taken and purified by a ProA affinity chromatography column to obtain chA2, chC3, chC, chD, chE2 recombinant proteins. chA2 variable region sequences are shown in SEQ ID No.3, chC3 variable region sequences are shown in SEQ ID No.4, chC9 variable region sequences are shown in SEQ ID No.5, chD9 variable region sequences are shown in SEQ ID No.6, chE2 variable region sequences are shown in SEQ ID No.7, wherein the corresponding CDRs (according to the definition of Kabat CDRs) are shown underlined and the constant region sequences are shown in SEQ ID No.8.

SEQ ID NO.1 MK-4830 heavy chain variable region amino acid sequence

EVQLQQWGAGLLKPSETLSLTCAVYGGSFSGYYWSWIRQPPGKGLEWIGEINHAGSTNYNPSLKSRVTISVDTSKNQFSLKLSSVTAADTAVYYCARLPTRWVTTRYFDLWGRGTLVTVSS

SEQ ID NO.2 MK-4830 light chain variable region amino acid sequence

ESVLTQPPSVSGAPGQRVTISCTGSSSNIGAGYDVHWYQQLPGTAPKLLIYGDSNRPSGVPDRFSVSKSGASASLAITGLQAEDEADYYCQSFDNSLSAYVFGGGTQLTVLGQPK

SEQ ID NO.3 chA2 VHH amino acid sequence

QVQLQESGGGSVQAGESLRLSCRASGSTSSYYYLGWFRQAPGKEREAVAAADNPKNLFAEHYADSVKGRFTISQDNTKNTLYLQMNSLKPEDTAVYFCAARLKGYDWRDAPHYTYWGQGTQVTVSS

The amino acid sequences of the CDRs 1, 2 and 3 of the chA2 antigen complementarity determining regions are SEQ ID NOs: 9. 10 and 11.

SEQ ID NO.4: chC3 VHH amino acid sequence

QVQLQESGGGSVQAGGSLRLSCAVSTYTYSTYSLGWFRQAAGKEREGVAVISTATGISWYADSVKGRFTISQDSTKNTLFLEMNDLKPEDTAVYYCAAGFHEADAPTLGVAGSTYPLSSFGYWGQGTQVTVSS

chC3 the amino acid sequences of the CDRs 1, 2 and 3 are SEQ ID NOs: 12. 13 and 14.

SEQ ID NO.5: chC9 VHH amino acid sequence

QVQLQESGGGSVQAGGSLNLSCTASHYTHSANYMGWFRQVSGKEREGVARIFIGSGSTIYADSVKGRFTISQDNAKRTTYLQMTSLEPEDTAVYYCAGCVASPWMCDLDPKNYGYWRQGTQVTVSS

chC9 the amino acid sequences of the CDRs 1, 2 and 3 are SEQ ID NOs: 15. 16 and 17.

SEQ ID NO.6: chD9 VHH amino acid sequence

QVQLQESGGGSVQAGGSRRLSCAASGNTENAGCMAWFRQAPGKGRQGVARIHGISGATYYTDSVKGRFTISQDKAKNTLYLQMNNLEPEDTAMYYCAATRLLYCSGAIVQGEYNYWGQGTQVTVSS

chD9 the amino acid sequences of the CDRs 1, 2 and 3 are SEQ ID NOs: 18. 19 and 20.

SEQ ID NO.7: chE2 VHH amino acid sequence

QVQLQESGGGSVQAGGSLRLSCTVSGYTGSFYLMAWFRQTPGKGPEGVAVIYPGDGSTDYDSSVKGRFTISRDNAENTIYLQMNNLKPADTATYYCAADVRPYGRRWDQGSEFDIWGQGTQVTVSS

The amino acid sequences of the chE2 complementarity determining region CDRs 1, 2 and 3 are SEQ ID NOs: 21. 22 and 23.

SEQ ID NO.8. Amino acid sequence of hFc constant region

ASEPKSSDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG

Example 3: chimeric antibody affinity detection

Antibody affinity was determined using an Octet QKe system instrument from Fortebio, using an anti-human antibody Fc fragment capture Antibody (AHC) biological probe capture antibody Fc fragment method. In the measurement, chA2, chC3, chC, chD9, chE2 chimeric antibody and control antibody MK-4830 were diluted to 4ug/ml with PBS buffer and passed over the surface of AHC probe (Cat: 18-0015, PALL) for 120s. LILRB2 recombinant protein (purchased from ACRO, cat#LI2-H5220) 60nm; as mobile phase, the binding time was 300s and the dissociation time was 300s. After the experiment is completed, the response value of the blank control is deducted, and the software is used for carrying out 1:1Langmuir binding pattern fitting, the kinetic constants of antigen-antibody binding were calculated.

Kinetic parameters are shown in the following table 1, and the results show that all the 5 chimeric antibodies bind to the LILRB2 recombinant protein, and the binding activity is equivalent to that of a control antibody.

TABLE 1 affinity assay results of chimeric antibodies with LILRB2 recombinant proteins

Sample of	KD(M)	kon(1/Ms)	kdis(1/s)
				MK-4830	7.84E-09	1.71E+05	1.34E-03
chA2	6.55E-10	1.37E+05	8.95E-05
				chC3	9.57E-09	3.43E+05	3.28E-03
chC9	2.86E-09	2.02E+05	5.77E-04
				chD9	8.30E-09	1.54E+05	1.28E-03
chE2	3.97E-10	2.73E+05	1.08E-04

Example 4: ELISA detection of binding Activity of anti-LILRB 2 chimeric antibodies

Human LILRB2-mFc recombinant protein (NCBI number: AAH36827, amino acids 22-461) was coated overnight at 4deg.C at a concentration of 1ug/mL; after washing the plate 3 times with PBS, 5% BSA PBS was added, the plate was blocked at 37℃for 60min, and the plate was washed 3 times with PBST; chA2, chC, chC9, chD, chE2 chimeric antibody and control antibody MK-4830 (3-fold gradient dilution 4 gradients from 10 ug/ml) were added at different dilution factors, incubated at 37℃for 60min, and PBST plates were washed 4 times; HRP-anti-human Fc (Cat: 109-035-098,Jackson Immuno Research) diluted 1:5000 was added, incubated 45min at 37℃and PBST plates were washed 4 times; adding TMB substrate for color development, and after incubation at 37 ℃ for 10min, adding 2M HCl to terminate the reaction; the absorbance A450nm-630nm of the well plate at the wavelength of 450nm was read and recorded with 630nm as a reference wavelength.

Experimental results show that chA2, chC3, chC9, chD9, chE2 chimeric antibody and control antibody MK-4830 can specifically bind to human LILRB2 recombinant protein (FIG. 1).

Example 5: FACS detection of binding Activity of anti-LILRB 2 chimeric antibody to 293 cells (human LILRB 2/293) recombinantly expressing human LILRB2

The binding of chimeric antibody to human LILRB2 was detected using 293 cells transiently transformed with human LILRB2 (human LILRB 2/293), and 2E5 cells were respectively bound to anti-LILRB 2 antibodies at different concentrations, chA2, chC3, chC, chD, chE2 and control antibody MK-4830, diluted 4-fold with 5 gradients from 264 nm. Incubation at 4deg.C for 60min in the dark, washing with PBS, adding FITC-labeled goat anti-human antibody (sigma, F9512) diluted 1:200, incubating at 4deg.C for 30min in the dark, washing with PBS, and resuspension in 200ul PBS, and flow cytometry detection.

The results show (FIG. 2) that chA2, chC, chC9, chD, chE2 chimeric antibodies and control antibody MK-4830 have comparable binding capacity.

Example 6: FACS detection of binding Activity of anti-LILRB 2 chimeric antibody to 293 cells (cyno LILRB 2/293) recombinantly expressing cynomolgus monkey LILRB2

The binding of chimeric antibody to cynomolgus monkey LILRB2 was detected using 293 cells transiently transformed with cynomolgus monkey LILRB2 (cyno LILRB 2/293), 2E5 cells were taken to bind to anti-LILRB 2 antibodies at different concentrations, chA2, chC3, chC9, chD, chE2 chimeric antibody and control antibody MK-4830, and 3-fold gradient dilutions were performed for 4 gradients from 10 ug/ml. Incubation at 4deg.C for 60min in the dark, washing with PBS, adding FITC-labeled goat anti-human antibody (sigma, F9512) diluted 1:200, incubating at 4deg.C for 30min in the dark, washing with PBS, and resuspension in 200ul PBS, and flow cytometry detection.

The results showed (fig. 3) that chC9 had strong binding activity to cynomolgus LILRB2 and that other antibodies bound poorly to cynomolgus LILRB2, suggesting that ChC9 may have different binding epitopes to several other molecules.

The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.

Claims

1. A nanobody against LILRB2, wherein said nanobody is capable of specifically binding to LILRB2 and the complementarity determining region CDRs of the VHH strand in said nanobody are one or more selected from the group consisting of:

(1) SEQ ID NO:15, CDR1, SEQ ID NO:16, and CDR2 as set forth in SEQ ID NO:17, CDR3;

(2) SEQ ID NO:18, CDR1, SEQ ID NO:19, and CDR2 as set forth in SEQ ID NO:20, and CDR3 shown in fig.

2. The nanobody of claim 1, wherein the nanobody is a humanized VHH or a camelized VHH.

3. The nanobody of claim 1 or 2, wherein the nanobody has a sequence as set forth in SEQ ID NO: 5. 6, or an amino acid sequence as set forth in any one of SEQ ID NOs: 5. 6, the amino acid sequence having at least 80% identity to the amino acid sequence set forth in any one of claims.

4. A fusion protein comprising a functional domain capable of specifically binding to LILRB2, said functional domain consisting of the nanobody of anti-LILRB 2 of any one of claims 1-3.

5. A pharmaceutical composition comprising the nanobody against LILRB2 of any one of claims 1-3, or the fusion protein of claim 4, and a pharmaceutically acceptable adjuvant.

6. An isolated nucleic acid molecule encoding the anti-LILRB 2 nanobody of any one of claims 1-3, or encoding the fusion protein of claim 4.

7. An expression vector comprising the nucleic acid molecule of claim 6.

8. A recombinant cell comprising the expression vector of claim 7.

9. A method of preparing a nanobody according to any of claims 1-3, characterized in that it comprises: culturing the recombinant cell of claim 8, and isolating and purifying the nanobody from the culture product.

10. Use of the anti-LILRB 2 nanobody of any one of claims 1-3, the fusion protein of claim 4, the composition of claim 5, the nucleic acid molecule of claim 6, the vector of claim 7, or the recombinant cell of claim 8 in the preparation of a medicament for preventing, treating and/or ameliorating a solid tumor or hematological tumor.

11. The use of claim 10, wherein the solid tumor is lung cancer, non-small cell lung cancer, pancreatic ductal carcinoma, endometrial cancer, hepatocellular carcinoma, melanoma, ovarian cancer, breast cancer, colorectal cancer, glioma, gastric cancer, renal cancer, testicular cancer, esophageal cancer, cervical cancer, bulb lung cancer, thyroid cancer, liver cancer, cancer of the urinary tract, or cancer of the head and neck.

12. The use according to claim 10, wherein the hematological neoplasm is chronic lymphocytic leukemia, acute myelogenous leukemia.