WO2020050628A1 - Novel immunotoxin production method - Google Patents

Abstract

The present invention relates to an immunotoxin production method and a cancer treatment composition using same, and more specifically, to an immunotoxin production method, an immunotoxin produced thereby and a cancer treatment composition, the immunotoxin production method comprising the site-specific binding of an immunoglobulin variant substituted by cysteine, to PE24 having an unnatural amino acid inserted therein. According to the present invention, by means of a technique for introducing reactive cysteine in a monoclonal antibody using site-directed mutagenesis, and a method for inserting an unnatural amino acid in a protein, biochemical properties, such as antigen binding by an antibody and catalyst activation by a toxin, are not affected, and an allogeneic immunotoxin exhibiting cytotoxicity to a cancer cell line may be produced, and thus the present invention may enable the production of various antibody-protein conjugates and may be applied for a cancer therapeutic agent.

Description

New immunotoxin manufacturing method

The present invention relates to a method for preparing an immunotoxin and a composition for treating cancer using the same, and more specifically, an immunotoxin characterized in that position-specific binding of an immunoglobulin variant substituted with cysteine to PE24 introduced with a non-natural amino acid is performed. It relates to a manufacturing method, an immunotoxin produced by the above manufacturing method, and a composition for treating cancer.

Antibodies are an essential part of the body's defense system. Antibodies present on the surface of B-lymphocytes identify and attack harmful substances such as viruses, bacteria and fungi. They are antigen-specific and consist of two identical heavy chains and two identical light chains. Both heavy and light chains have variable regions and constant regions. The N-terminal, called the variable region (V _H , V _L ), is responsible for antigen specificity, and the constant region comprises three domains (C _H1 , C _H2 , C _H3 ) of the heavy chain and one domain (C _L ) of the light chain. Includes. There are two structural parts of the antigen-binding fragment (Fab) and the constant fragment (Fc) (Fig. 1). Fab includes V _H and V _L , can recognize antigens and neutralize pathogens, and the Fc region consists of 2 CH ₂ and 2 CH ₃ domains. The heavy and light chains are linked by disulfide (-SS-) bonds and held together by non-covalent interactions. There are five types of immunoglobulins (IgG, IgA, IgD, IgM, and IgE), and there are structural differences that have specific properties suitable for specific functions. Of these, IgG is mainly applied to therapeutic agents. Antibodies cannot destroy antigens alone, but can block target antigens or kill cells through an immune system such as complement, phagocytes or NK cells (Wang, W., et al., Journal of pharmaceutical sciences, 2007 96 (1): p. 1-26).

In 1975, a technique for making monoclonal antibodies from hybridoma cells was developed (Kohler, G. and C. Milstein, Nature, 1975. 256 (5517): p. 495-497.). Hybridoma cells can be made by fusing B cells and malignant tumor cells with a chemical compound, and these hybridoma cells can be permanently cultured to make only specific antibodies. Although this technique can produce high-purity antibodies with high specificity and affinity, the clinical success of mouse monoclonal antibodies has been limited. This is because there is a problem of high immunogenicity derived from a non-human species (mouse or rat). To overcome the problems associated with non-human antibodies, genetic engineering has been developed for chimeric, humanized and human antibodies. Chimeric antibodies are composed of murine variable regions and human constant regions (Morrison, SL, et al., Proceedings of the National Academy of Sciences, 1984. 81 (21): p. 6851-6855). Humanized antibodies are generated by transplanting mouse complementarity-determining regions (CDRs) into human variable and constant regions (Jones, PT, et al., Nature, 1986. 321 (6069): p. 522-525 ). Fully human antibodies can be produced using phage display technology and transgenic mice. Phage display is an in vitro screening technique that uses bacteriophage to link proteins (Gram, H., et al., Journal of immunological methods, 1993. 161 (2): p. 169-176). Many monoclonal antibodies are currently approved as therapeutic drugs, and therapeutics based on monoclonal antibodies have high specificity, selectivity, and long half-life, but many cancers are resistant to treatment with monoclonal antibodies alone (Villamor, N., E. Montserrat, and D. Colomer. Seminars in oncology. 2003 Aug; 30 (4): 424-33). In addition, the large protein size makes it difficult to penetrate solid tumors. To overcome these limitations, various strategies have been developed, for example, modification of host responses, direct targeting of tumor cells, and delivery of cytotoxic substances (Ray, P. and RR White, Pharmaceuticals, 2010). 3 (6): p. 1761-1778).

Antibody-drug conjugates (ADCs) are one of the ideal targeted therapies that can kill cancer cells without leaving normal cells. Antibodies are combined with cytotoxic drugs and delivered to cancer cells (Alley, SC, NM Okeley, and PD Senter, Current opinion in chemical biology, 2010. 14 (4): p. 529-537). ADC development has been continued, but there is a homogeneity problem of the ADC molecule. Previously studied ADCs had a drug-to-antibody (DAR) ratio of 0 to 8, so pharmacokinetics and in vivo performance were different (Hamblett, KJ, et al., Clinical cancer research, 2004. 10 ( 20): p. 7063-7070). Conventional binding methods for producing ADCs use lysine, which is solvent-accessible, or cysteine with reduced cross-chain disulfide bonds. Because of human IgG containing about 100 lysine residues, lysine chemical binding results in 0 to 8 conjugated molecules per antibody. Thus, a number of different ADC species can be produced (Wang, L., et al., Protein science, 2005. 14 (9): p. 2436-2446). Cysteine chemical bonding is achieved through reduction of the disulfide bonds between the four chains, thus making the eight free thiol groups the linker-drug attachment site. Therefore, each of the conjugates produced by the two methods is composed of both unconjugated and overloaded forms. In antigen binding, drug-binding species are hindered by unconjugated antibodies, reducing therapeutic activity. On the other hand, drug-binding species (DAR> 4) have antibody aggregation, low stability, and rapid kidney clearance (Sun, MM, et al., Bioconjugate chemistry, 2005. 16 (5): p. 1282-1290).

Because it can target protein synthesis, one of the most common biological processes, toxins were developed by conjugation or fusion to target-specific binding molecules such as antibodies. Initially, toxins without the target-binding domain or variants thereof were chemically bound to IgG using lysine chemistry, but the product was heterogeneous, which was a serious obstacle to development as a therapeutic agent. To overcome the limitations, toxin variants were expressed by fusion to antibody fragments in E. coli . However, it had the disadvantages of short half-life because of its small size and no Fc domain.

In the early 1980s, many researchers studied protein toxins from a variety of bacteria, such as various plants and ricin, diphtheria toxin, and Pseudomonas exotoxin, to produce immunotoxins. Immunotoxins include monoclonal antibodies or ligands for target specificity and potent toxins for cell killing effects. In general, an enzyme that induces cytotoxicity in cells is used as an immunotoxin (Blythman, HE, et al., Nature, 1981. 290 (5802): p. 145-146). In most cases, the original cellular binding domain of the toxin is replaced by the scFv or Fab of the monoclonal antibody to reduce nonspecific binding to normal cells. Recombinant DNA technology provides genetically fused immunotoxins, which show similar cytotoxicity and improved allogeneic products (Pastan, I., et al., Nature Reviews Cancer, 2006. 6 (7): p. 559-565; Alewine, C., R. Hassan, and I. Pastan, The oncologist, 2015. 20 (2): p. 176-185). Since the first successful in vivo immunotoxin study in 1981, several clinical studies of immunotoxins have been conducted. However, there are side effects such as vascular leak syndrome, immunogenicity and hepatotoxicity (Kreitman, RJ, et al., Journal of Clinical Oncology, 2012. 30 (15): p. 1822 -1828), efforts are being made to overcome these limitations.

Immunotoxins have been developed for targeted cancer treatment. These chimeric proteins, consisting of a targeting moiety of a monoclonal antibody or ligand that binds to a cancer cell surface receptor, and powerful proteins such as bacteria and plant-derived toxins, have demonstrated a strong ability to kill cancer cells. Chemical conjugation or fusion protein methods have been studied as a means to obtain immunotoxins, but most chemical binding methods produce heterogeneous products, and fused forms of immunotoxins are full-length. ) It has been reported only for antibody fragments rather than antibodies.

Accordingly, the present inventors tried to develop an immunotoxin to which a full-length antibody and a toxin are site-specifically coupled, in order to develop an effective immunotoxin for the treatment of cancer, using immunoglobulins and site-specific mutagenesis By using reactive cysteine in monoclonal antibody to produce homogeneous ADC (THIOMAB technology) and the method of introducing non-natural amino acids into proteins derived from Pseudomonas exotoxin A, the conjugates produced are homologous ( homogeneous) product, maintaining antigen specificity, confirming that it exhibits cytotoxic activity against cancer cell lines, and completed the present invention.

The above information described in this background section is only for improving the understanding of the background of the present invention, and thus does not include information that forms prior art already known to those of ordinary skill in the art. It may not.

Summary of the invention

An object of the present invention is to provide a method for producing an immunotoxin to which an immunoglobulin and a toxin are site-specifically bound.

Another object of the present invention is to provide a composition for the treatment of cancer comprising the immunotoxin produced by the above production method and the same.

In order to achieve the above object, the present invention comprises the steps of (a) reducing and re-oxidizing an immunoglobulin variant in which a part of amino acid residues are substituted with cysteine, and then linking with a linker; And (b) provides a method for producing an immunotoxin (immunotoxin) comprising the step of generating an immunotoxin by conjugating the protein PE24 in which the linker-linked immunoglobulin variant and the unnatural amino acid are introduced.

The present invention also provides an immunotoxin (immunotoxin) conjugated with a protein PE24 in which an unnatural amino acid is introduced via a linker through an immunoglobulin variant in which a part of amino acid residues is substituted with cysteine.

The present invention also provides a composition for the treatment of cancer comprising the immunotoxin.

The present invention also provides a method of treating cancer comprising administering the immunotoxin.

The present invention also provides the use of said immunotoxin for the treatment of cancer.

The present invention also provides the use of said immunotoxin for the manufacture of a medicament for the treatment of cancer.

1 is a schematic diagram of position-specific binding using a linker between PE24 containing an unnatural amino acid and an immunoglobulin variant in which a part of amino acid residues are substituted with cysteine.

Figure 2 shows the SDS-PAGE analysis of the immunoglobulin variant screening substituted with cysteine, all data was observed after the reduction and reoxidation process. Lane 1 is Intact Trastuzumab, Q416C, N418C, etc. correspond to the variants described in the Examples.

Figure 3 shows the modified Pseudomonas Exotoxin A (PE24) structure.

Figure 4 shows the SDS-PAGE and Western blot analysis for the PE24 expression test. WC is 1% SDS treatment and 95 ° C boiling, then the whole cell lysates, Sol is B-PER treatment soluble fraction, Ins represents soluble fraction from soluble fraction pellets, Peri is periplasmic fraction, Sph is spheroplast (periplasmic fraction upper layer) After removing the liquid, it means lysed pellets obtained by using 1% SDS and boiling at 95 ℃.

Figure 5 shows the SDS-PAGE analysis of purified PE24. FIG. 5A is PE24 purified from E. coli cultured through a periplasmic fraction, and FIG. 5B is PE24 repurified after thrombin treatment. Lanes 1 to 5 represent elution fractions (Lane 1 *: PE24 after thrombin treatment. Lane 2 *: column flow through fraction from Lane 3 * to Lane 5 * was eluted with lysis buffer).

6 shows an overview of the antibody-protein conjugation process.

7 shows SDS-PAGE analysis of Trastuzumab-PE24 binding. SDS-PAGE analysis was performed under non-reducing and reducing conditions (Lane 1: intact Trastuzumab N418C variant, reduced antibody using Lane 2: fold TECP, re-oxidized antibody using Lane 3: dhAA, Lane 4: intact PE24, Lane 5: Trastuzumab N418C and PE24 conjugate mixture, Lane 6, 7, 8: reducing conditions of Lane 1, 4, 5, respectively).

8 is a SDS-PAGE result showing the conjugation of the Trastuzumab variant with PE24-AzF. Analysis of SDS-PAGE was performed under reduced, reoxidized and non-reduced conditions for PE24 conjugated trastuzumab.

9 shows SDS-PAGE analysis of purified Trastuzumab-PE24 conjugate. Figure 9a is the size exclusion chromatography results, the 21 to 25 fractions were additionally purified by anion exchange chromatography (left), and each fraction was analyzed through SDS-PAGE (right). Figure 9b is anion exchange chromatography results, 21 to 25 fractions of size exclusion chromatography were further purified using anion exchange chromatography (left), and the fraction of each peak was analyzed by SDS-PAGE (right).

10 is a graph showing evaluation of Her2 / neu binding affinity by indirect ELISA. The 96 well plate was coated with Her2 / neu antigen, and the detection antibody protein L-HRP conjugate was used at a ratio of 1: 500. After the TMB solution treatment, the absorbance signal was measured at 450 nm with a plate reader.

11 shows the binding and uptake of trastuzumab (a) and trastuzumab-PE24 (b) to Her2 positive cells. MDA-MB-231 (Her2 negative) or MDA-MB-453 (Her2 positive) cells were incubated with Trastuzumab or Trastuzumab-PE24 for 30 minutes at 4 ° C. To induce the cell endocytosis pathway, MDA-MB-453 cells were incubated for another 4 hours at 37 ° C (bottom). Cells were stained with anti-human antibody-Alexa 488 and Hoechst and images were obtained using a confocal fluorescence microscope.

Figure 12 shows the binding of trastuzumab-PE24 conjugates to the following Fc receptors measured by ELISA: (a) hC1q, (b) FcRn at pH 6.0, (c) FcRn at pH 7.4, (d) FcrRI, (e) FcrRIIa (H), (f) FcrRIIa (R), (g) FcrRIIb, (h) FcrRIIIa (F), (i) FcrRIIIa (V). hC1q is complement component 1q; FcRn is a neonatal Fc receptor (neonatal Fc receptor); FcrRI is Fc gamma receptor I (Fc gamma receptor I); FcrRIIa (H) is an Fc gamma receptor IIa (H134); FcrRIIa (R) is an Fc gamma receptor IIa (R134); FcrRIIb: Fc gamma receptor IIb; FcrRIIIa (F) includes Fc gamma receptor IIIa (F158); FcrRIIIa (V) is Fc gamma receptor IIIa (V158).

13 shows the scheme of the ADP-ribosylation assay.

Figure 14 shows Western blot analysis for ADP-ribosylation activity at each concentration of the conjugate (Lane 1: Wheat embryo extract containing NAD-biotin without PE24, Lane 2: NAD-biotin and PE24 at each concentration) Wheat germ extract, wheat embryo extract containing lane 3: NAD-biotin and Trastuzumab-PE24 conjugate at each concentration.All western blot data were measured by streptavidin-HRP).

15 is a graph showing the cell viability of a breast cancer cell line. a and b are Her2 / neu positive cell lines, and c are Her2 / neu negative cell lines. Cytotoxicity was measured by WST-8 assay according to the manufacturer's instructions.

16 shows the schematic structure of BONCAT.

Figure 17 shows Western blot analysis for protein inhibition of the Trastuzumab-PE24 conjugate, HCC1954 is a Her2 / neu positive cell line, and MDA-MB-231 is a Her2 / neu negative cell line (Lane 1: protein untreated 4 mM AHA, Lane 2: protein untreated 4 mM AHA and 100 μg / ml cycloheximide, Lane 3: 0.1 nM intact Trastuzumab and 4 mM AHA, Lane 4: 0.1 nM intact PE24 and 4 mM AHA, Lane 5: 0.1 nM Trastuzumab-PE24 conjugate and 4 mM AHA.All Western blot data were measured by streptavidin-HRP). Western blot results for GAPDH were used to confirm the amount of protein loading used in the data.

Figure 18 shows the conjugation and purification of Cetuximab-HC-N418C and PE24-AzF. It proceeded according to the method of conjugation and purification using trastuzumab. Figure 18a was performed under non-reducing conditions by SDS-PAGE analysis of the reduction and oxidation results of cetuximab. FIG. 18B shows the results of conjugation and size exclusion chromatography (left), and fractions 14 to 23 were analyzed through SDS-PAGE (right). Figure 18c is anion exchange chromatography results, 15 to 19 fractions of size exclusion chromatography were further purified by anion exchange chromatography (left), and analyzed by SDS-PAGE (right). Among them, 6 to 16 fractions are isolated in the form of a single PE24 conjugated to the cetuximab antibody.

Detailed description of the invention and preferred embodiments

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. In general, the nomenclature used herein is well known in the art and commonly used.

Antibody-drug conjugates (ADCs) have been developed for decades, but have produced heterogeneous products. Heterogeneity limited the use of ADCs as therapeutic agents. Various binding chemistry methods have been developed to solve this problem. Attempts to generate homogeneous ADCs have created THIOMAB technology that produces ADCs with fixed stoichiometry by introducing engineered cysteines into the heavy or light chain of the antibody.

Immunotoxins are another anti-cancer strategy consisting of targeting moieties such as antibodies of the ligand and cytotoxic toxin proteins. First- and second-generation immunotoxins have had limited use as therapeutic agents because they produce heterogeneous products due to uncontrollable chemical binding. To solve this problem, the third generation immunotoxin was developed in E. coli through a fusion protein method. The product showed less heterogeneity than the previous method, but the expression of fused full-length IgG and PE was unsuccessful. As a result, only PE fused with a small antibody fragment was expressed, and showed a short half-life.

The object of the present invention is to develop a position-specific binding method for full-length IgG and protein. Antibody-protein conjugation strategies have been proposed based on THIOMAB technology and the method of introducing non-natural amino acids into proteins. In addition, biochemical properties and cytotoxicity were evaluated in various cancer cell lines. The results show that the method according to the invention can be applied to the production of various antibody-protein conjugates.

Accordingly, the present invention, in one aspect, (a) reducing and re-oxidizing an immunoglobulin variant in which a part of the amino acid residue is substituted with cysteine, and then linking with a linker; And (b) conjugating a protein PE24 in which the linker-linked immunoglobulin variant and unnatural amino acid are introduced to generate an immunotoxin.

In the present invention, the linker-linked immunoglobulin variant and the non-natural amino acid-introduced protein PE24 may be site-specifically bound by a click reaction.

In one embodiment of the present invention, a conjugate in which trastuzumab or cetuximab containing a cysteine mutation and PE24 containing a non-natural amino acid was site-specifically conjugated through a maleimide-PEG-DBCO Linker was prepared. The alkyne group contained in the linker and the azide group contained in the non-natural amino acid are reacted under a conventional click reaction system (Formula 1) to specifically bind trastuzumab or cetuximab with PE24 do.

[Formula 1]

In one embodiment of the present invention, the conjugate exhibited antigen binding affinity and ADP-ribosylation activity similar to Trastuzumab and PE24, respectively, which consisted of a chemical reaction for cysteine manipulation of IgG, binding and binding of non-natural amino acids to PE This means that the binding method does not affect the properties of the conjugated molecule.

As used herein, the term “immunoglobulins” is a plasma protein containing an antibody, and there are five types of immunoglobulin (Ig) M, IgD, IgG, IgA and IgE, respectively, heavy chain constant region genes μ, δ, γ, α , ε. In antibody technology, IgG is mainly used. There are four isotypes of IgG1, IgG2, IgG3, and IgG4, and each structure and functional property are different.

IgG forms a very stable structure (molecular weight, 150 kDa) in the shape of a Y made of two heavy chain (50 kDa) proteins and two light chain (25 kDa) proteins. The light chain and heavy chain of an antibody are divided into a variable region having a different amino acid sequence for each antibody and a constant region having the same amino acid sequence. In the heavy chain constant region, C _H1 , H (hinge), C _H2 , C _H3 domain is present. Each domain is composed of two β-sheets, and intramolecular disulfide bonds are connected between them. Two variable regions of the heavy chain and the light chain are combined to form an antigen binding site, and each of these sites is present in each of the Y-shaped arms, and Fab (antibody binding fragment) is a part capable of binding to these antigens. ), And the portion that cannot bind to the antigen is called an Fc (crystalizable fragment). Fab and Fc are linked by flexible hinge regions.

The “antibody” refers to an immunoprotein that binds to an antigen and interferes with the action of the antigen or removes the antigen. The concept includes both a polyclonal antibody and a monoclonal antibody, preferably a monoclonal antibody, and may have an intact whole antibody form.

In the present invention, the immunoglobulin variant may be characterized in that it is a full-length monoclonal IgG, and may be characterized as being an IgG type monoclonal antibody, but is not limited thereto.

The method for producing an immunotoxin according to the present invention includes substituting a part of the amino acid residues of immunoglobulins with cysteine.

In the present invention, the immunoglobulin variant is the 61st, 91st, 273th, 303th, 305th amino acids of the heavy chain constant region amino acid sequence represented by SEQ ID NO: 18; The amino acids 61, 91, 272, 302, and 304 of the heavy chain constant region amino acid sequence represented by SEQ ID NO: 22; And a light chain constant region amino acid sequence represented by SEQ ID NO: 20, 91 th, 93 th amino acids; any amino acid selected from the group consisting of cysteine may be substituted.

The heavy and light chain amino acid sequences of the immunoglobulin variants are shown in Table 1 below.

The amino acids in bold in Table 1 correspond to residues that can be substituted with cysteine, and the underlined portions indicate hinge regions.

In the present invention, the 61st, 91st, 273th, 303th, 305th amino acids of the heavy chain constant region amino acid sequence represented by SEQ ID NO: 18 or the 61st, 91th of the heavy chain constant region amino acid sequence represented by SEQ ID NO: 22 The second, 272, 302, and 304 amino acid residues correspond to HC-G174, HC-N204, HC-N386, Q416, and HC-N418, respectively, when represented by the Kabat numbering system, SEQ ID NO: 20 The 91th and 93th amino acid residues of the light chain constant region amino acid sequence represented by are LC-T197 and LC-Q199.

In one embodiment of the invention, the trastzumab or cetuximab variant is a heavy chain (HC) -Q416, HC-N418, HC-N386, HC-N204, HC-G174, LC (light chain)- Any amino acid selected from the group consisting of T197 and LC-Q199 was substituted with cysteine. The amino acid residue number of the trastuzumab or cetuximab variant is according to the Kabat numbering system commonly used in the art (Kabat et al., In “of Proteins of Immunological Interest” 5th Ed., US EU Index number as in Department of Health and Human Services, NIH Publication No. 91-3242, 1991).

In one embodiment of the invention, cysteine substitutions were introduced using THIOMAB technology to produce homologous ADCs by introducing reactive cysteines into monoclonal antibodies using site-directed mutagenesis (Junutula , JR, et al., Nature biotechnology, 2008. 26 (8): p. 925-932).

The THIOMAB technology has been proposed as a solution to the heterogeneity problem. Engineered cysteine residues can be paired with other natural cysteines or glutathiones formed during the fermentation process, reducing activity. To this end, a phage display-based ELISA called PHESELECTOR was developed. As a model system, trastuzumab-Fab (hu4D5Fab) was used to construct an unpaired cysteine residue with high activity that does not interfere with antigen binding, and cannot interact with antigen binding. To apply this system to full-length antibodies, antigen binding was compared to the original anti-MUC16 antibody using an anti-MUC16 THIOMAB-drug conjugate in which alanine residues of the heavy chain were substituted with cysteine residues (HC-A114C). THIOMAB, including anti-MUC16 mAb and vcMMAE, was produced by reduction and reoxidation of interchain disulfide bonds, which created two free thiol groups for binding. Subsequently, the reaction of these free thiols with the maleimide group of the linker was carried out. This method produced a position-specifically coupled ADC (DAR ~ 2) compared to the existing anti-MUC16 antibody (DAR ~ 3.5), and showed similar anti-tumor activity in in vitro and in vivo studies. In animal model studies conducted in rats and cynomolgus monkeys, THIOMAB-drug conjugates (TDCs) showed a greater therapeutic index than conventional ADCs. These results suggest that THIOMAB technology can be used to generate homozygotes with improved therapeutic index and pharmacodynamics compared to conventional ADCs (Junutula, JR, et al., Nature biotechnology, 2008. 26 (8) : p. 925-932; Junutula, JR, et al., Clinical Cancer Research, 2010. 16 (19): p. 4769-4778).

In the present invention, the cysteine substitution may be characterized by occurring through a PCR reaction using a primer, and the primer may be characterized by being represented by any one or more sequences selected from the group consisting of SEQ ID NOs: 1 to 16. have.

The method for preparing an immunotoxin according to the present invention includes the step of reducing and reoxidizing an immunoglobulin substituted with cysteine and then binding it with a linker.

In the present invention, the reduction may be characterized in that it is made by using tris (2-carboxyethyl) phosphine (TCEP) as a reducing agent. In addition, the re-oxidation may be characterized by using dihydroascorbic acid (dhAA) as an oxidizing agent, but is not limited thereto.

In the present invention, the linker may be characterized in that it is a maleimide (maleimide) -PEG-DBCO linker. In one embodiment of the present invention, using a maleimide-PEG-DBCO, a secondary functional linker containing maleimide and DBCO groups, a Trastuzumab or Cetuximab variant with N418C mutation and a PE24 protein having an azide group Site-specific binding.

The method for preparing an immunotoxin according to the present invention includes the step of generating an immunotoxin by conjugating a protein PE24 in which an unnatural amino acid is introduced with the linker-linked immunoglobulin variant.

In the present invention, the PE24 may be characterized by deimmunized Pseudomonas Exotoxin A.

A variety of toxins such as diphtheria toxin (diphtheria toxin), gel Ronin (gelonin), Pseudomonas exotoxin (Pseudomonas exotoxin (PE)) were studied in order to produce immunotoxins. One of them, an immunotoxin based on Pseudomonas exotoxin A, has been actively studied for the development of anticancer drugs. Since Pseudomonas exotoxin A-based immunotoxin has only been reported as a minor vascular leak syndrome (VLS) as a side effect, PE-based immunotoxin is advantageous for clinical development unlike other immunotoxins such as ricin.

Pseudomonas aeruginosa is a gram-negative bacterium, and is widely recognized as a human pathogen. Pseudomonas Exotoxin A is the most toxic protein that catalyzes the inactivation of eukaryotic elongation factor 2 (eEF-2) through ADP-ribosylation (Domenighini, M. and R. Rappuoli, Molecular microbiology, 1996 21 (4): p. 667-674). eEF-2 is an essential material for protein synthesis. Therefore, Pseudomonas Exotoxin A induces cell death through protein synthesis inhibition (Hafkemeyer, P., et al., Human gene therapy, 1999. 10 (6): p. 923-934).

In the present invention, the PE24 is Pseudomonas Exotoxin ( Pseudomonas Exotoxin) A domain Ia is deleted, domain II excluding the purin-cleavable motif is deleted, 7 mutations (R427A, R456A, D463A, R467A , R490A, R505A and R538A) may include a domain III of a toxin, and additionally His 6 tags and a thrombin cleavage site were introduced.

PE is expressed as a single 638 amino acid (69 kDa) polypeptide and becomes 613 amino acids (66 kDa) by removing 25 N-terminal amino acids during secretion. According to X-ray crystallography studies, PE has three major structural domains (Wedekind, JE, et al., Journal of molecular biology, 2001. 314 (4): p. 823-837 ). In addition, PE belongs to the AB toxin family consisting of a receptor binding domain (B subunit) and a cytotoxic active domain (A subunit) (Odumosu, O., et al., Toxins, 2010. 2 (7): p. 1612- 1645). Domain Ia (aa 1-252) is a B subunit responsible for receptor binding. Domain II (aa 253-364) with six consecutive α-helices is involved in translocation through the cell membrane. Domain III is a catalytic subunit that plays an important role in ADP-ribosyltransferase activity. The function of domain Ib (aa 365-404) is unknown, but part of domain Ib (aa 395-404) is required for catalytic activity of domain III (Kihara, A. and I. Pastan, Bioconjugate chemistry, May 5, 1994) (6): p. 532-538).

When PE is secreted, the toxin's C-terminal lysine (aa 613) is cleaved by the host's carboxypeptidase to generate a REDL sequence capable of binding to the Golgi's KDEL receptor. After the toxin domain Ia binds to the cell surface receptor LRP1, PE is internalized through clathrin-coated pits. The PE molecule undergoes proteolysis in the furin-cleavable motif of domain II (RHRQPRG, aa 274-280 corresponds to the furin cleavage site) (Ref ogata et al, 1992). Decomposition produces two PE fragments, a 28 kDa (B subunit) N-terminal fragment and a 37 kDa C-terminal fragment (A subunit) (Ogata, M., et al., Journal of Biological Chemistry, 1992. 267 (35): p. 25396-25401). Even after furin cleavage, the two fragments are joined due to the disulfide bonds of C-265 and C-287 surrounding the furin cleavage site. Protein disulfide isomerase (PDI) reduces disulfide bonds, resulting in a 37 kDa PE fragment containing a REDL sequence (aa 609-612) that binds to the KDEL receptor and is transported to the ER in a retrograde manner. Finally, the 37 kDa fragment reaches the cytoplasm through the ER-related proteolytic pathway (ERAD) and catalyzes ADP ribosylation for eEF-2 which induces protein synthesis inhibition and ultimately cell death (Michalska, M. and P. Wolf, Frontiers in microbiology, 2015. 6).

Unlike natural exotoxin A, exotoxin A, developed as an immunotoxin, binds to antibodies or ligands, enabling target-specific binding. Several types of immunotoxins have been developed, but they all kill cancer cells through mechanisms similar to natural toxins. Therefore, it can be used for various cancer treatments.

Initial studies (also called first-generation immunotoxins) in which native PE was chemically bound to full-length antibodies or receptor ligands have reached the limit of non-specific killing of normal cells. It has been shown that by removing the cell-binding domain from the toxin, the second generation immunotoxin in which the toxin's domain Ia has been replaced with a variable fragment of the antibody (Fv) is more applicable to animals. However, since they are also produced by chemical bonding, such as the first immunotoxin, heterogeneous products are produced, thereby limiting therapeutic applications. Recombinant DNA technology has been introduced to produce third generation immunotoxins. The cell recognition domain of the toxin is replaced by a variable fragment of an antibody in which heavy (VH) and light (VL) chains are linked by peptide linkers or stabilized by disulfide-linked Fv (Shapira, A. and I. Benhar, Toxins, 2010. 2 (11): p. 2519-2583).

On the other hand, PE40 (aa 253-613) with domain Ia removed (Kondo, T., et al., Journal of Biological Chemistry, 1988. 263 (19): p. 9470-9475) and additionally domain Ib portion (365- 380) -removed PE38 (aa 253-334 and 381-613) (Theuer, CP, et al., Cancer research, 1993. 53 (2): p. 340-347) was developed for immunotoxin construction. In particular, there are various types of PE38-based immunotoxins, some of which are undergoing clinical studies (Mazor, R., M. Onda, and I. Pastan, Immunological reviews, 2016. 270 (1): p. 152-164 ). However, treatment effects are limited due to dose-limiting toxicity and side effects such as vascular leakage syndrome (Kreitman, R.J., et al., Journal of Clinical Oncology, 2000. 18 (8): p. 1622-1636). In order to avoid lysosomal degradation that may occur in the process of reaching the cytoplasm, most of the domain II except the furin cleavage sequence RHRQPRGWEQ, which is important for toxin activity, was removed, and showed cytotoxicity similar to that of intact PE38 (Weldon, JE, et. al., Blood, 2009. 113 (16): p. 3792-3800). Clinical studies show that since PE is a bacterial derived toxin, 92% of patients treated with PE38-based immunotoxins produce neutralizing antibodies after the first cycle (Powell, DJ, et al., The Journal of Immunology, 2007. 179 ( 7): p. 4919-4928). Recently, Roche and the National Institutes of Health (NIH) have developed an anti-mesothelin immunotoxin called RG7787 (Hollevoet, K., et al., Molecular cancer therapeutics, 2014. 13 (8): p. 2040-2049.). De-immunized immunotoxins consist of humanized Fabs and toxins with B cell and T cell epitopes removed, and anti-tumor activity has been demonstrated in animal models. RG7787 is currently called LMB-100, and a phase 1 study is under way to treat malignant mesothelioma.

In the present invention, the non-natural amino acid may be characterized as being para-azidophenylalanine (p-azidophenylalanine), but is not limited thereto.

There are 20 amino acids in nature, and they function as protein building blocks for biological processes. Conversely, there are unnatural amino acids (UAA) with special properties such as detection probes or chemical reactivity in the side chain (Liu, C.C. and P.G. Schultz, Annual review of biochemistry, 2010. 79: p. 413-444). For example, a protein containing an azide or alkyl group can be combined with other molecules through a click reaction (Jewett, JC and CR Bertozzi, Chemical Society Reviews, 2010. 39 (4): p. 1272-1279), and benzo Proteins comprising a phenone group can be used for photo-crosslinking with other molecules (Hino, N., et al., Nature methods, 2005. 2 (3): p. 201-206). Numerous non-natural amino acids have been developed, and more than 50 UAAs have been introduced into proteins in several fields (Wals, K. and H. Ovaa, Frontiers in chemistry, 2014. 2). The ability to be conjugated to other materials can be applied to ADCs (Axup, JY, et al., Proceedings of the National Academy of Sciences, 2012. 109 (40): p. 16101-16106), and has a probe property ratio Natural amino acids can be applied to diagnostic reagents for biosensors (Lee, HS, et al., Journal of the American Chemical Society, 2009. 131 (7): p. 2481-2483). In addition, protein stability may be increased through the introduction of non-natural amino acids (Kwik, W., K. Ang, and G. Chen, Journal of Inorganic and Nuclear Chemistry, 1980. 42 (2): p. 303- 313).

Production systems through E. coli , yeast and mammalian cell lines have been developed to produce proteins containing non-natural amino acids. Two factors are required to position-specifically bind a non-natural amino acid to a protein. The unique codon is a stop or quadruplet codon (Anderson, JC, et al., Proceedings of the National Academy of Sciences of the United States of America, 2004. 101 (20): p. 7566-7571), usually encoding a natural amino acid (Chen, G.-FT and M. Inouye, Nucleic acids research, 1990. 18 (6): p. 1465-1473). UAG, UGA, UAA and AGGA codons belong to the stop codon and quadruplet codon, respectively (O'donoghue, P., et al., FEBS letters, 2012. 586 (21): p. 3931-3937). Another factor is an orthogonal aminoacyl-tRNA synthetase (aaRS) / tRNA pair derived from another species to avoid confusion with endogenous tRNA, aminoacyl tRNA synthetase and amino acids in the host organism. Derived from Methanococcus jannaschil ( Mj )

The pair was used to introduce a non-natural amino acid into the TAG stop codon in E. coli (Wang, L. and PG Schultz, Chemistry & biology, 2001. 8 (9): p. 883-890). Various non-natural amino acids can be site-specifically linked through this technique, which can be applied to various fields such as ADC.

In the present invention, the immunoglobulin may be characterized as Trastuzumab or Cetuximab, but is not limited thereto.

In the present invention, Herceptin is a brand name of “Trastuzumab”, a monoclonal antibody targeted to the HER2 / neu receptor and used to treat breast cancer. In the present invention, Herceptin and Trastuzumab have the same meaning. Is used. In the present invention, the trastuzumab can be used alone or in combination with other chemotherapy drugs.

In the present invention, “cetuximab” is an epidermal growth factor receptor (EGFR) inhibitor, and is used in the treatment of metastatic colorectal cancer, metastatic non-small cell lung cancer, and head and neck cancer (mouse / human). It is a monoclonal antibody.

In another aspect, the present invention relates to an immunotoxin in which an immunoglobulin variant in which a part of amino acid residues is substituted with cysteine is conjugated with a protein PE24 in which unnatural amino acid is introduced via a linker. will be.

In the present invention, the immunoglobulin variant is the 61st, 91st, 273th, 303th, 305th amino acids of the heavy chain constant region amino acid sequence represented by SEQ ID NO: 18; The amino acids 61, 91, 272, 302, and 304 of the heavy chain constant region amino acid sequence represented by SEQ ID NO: 22; And a light chain constant region amino acid sequence represented by SEQ ID NO: 20, 91 th, 93 th amino acids; any amino acid selected from the group consisting of cysteine may be substituted.

In one embodiment of the invention, the trastzumab or cetuximab variant is a heavy chain (HC) -Q416, HC-N418, HC-N386, HC-N204, HC-G174, LC (light chain)- Any amino acid selected from the group consisting of T197 and LC-Q199 was substituted with cysteine.

In the present invention, the linker may be characterized in that it is a maleimide (maleimide) -PEG-DBCO linker.

In the present invention, the PE24 may be characterized in that it is deimmunized Pseudomonas Exotoxin A.

In the PE24, the domain Ia is deleted from Pseudomonas Exotoxin A, and the domain II is deleted except for the purin-cleavable motif, and 7 mutations (R427A, R456A, D463A, R467A, R490A, R505A, and R538A), including domain III of the toxin, and may further be characterized by introduction of His 6 tags and a thrombin cleavage site.

In the present invention, the immunoglobulin may be characterized by being trastuzumab or cetuximab.

In another aspect, the present invention relates to a composition for treating cancer comprising the immunotoxin.

In another aspect, the present invention relates to a method for treating cancer, characterized in that the immunotoxin is administered to a patient in need of treatment.

In another aspect, the present invention relates to the use of said immunotoxin for the treatment of cancer.

In another aspect, the present invention relates to the use of said immunotoxin for the manufacture of a medicament for the treatment of cancer.

The cancer is, for example, lung cancer, peritoneal cancer, colon cancer, biliary tract tumor, nasopharyngeal cancer, larynx cancer, bronchial cancer, oral cancer, osteosarcoma, gallbladder cancer, kidney cancer, leukemia, bladder cancer, melanoma, brain cancer, glioma, brain tumor, skin cancer, pancreatic cancer, breast cancer , Liver cancer, bone marrow cancer, esophageal cancer, colorectal cancer, stomach cancer, cervical cancer, prostate cancer, ovarian cancer, non-small cell lung cancer, head and neck cancer and rectal cancer may be any one or more selected from the group, more preferably breast cancer, colon cancer, arsenic Cell lung cancer or head and neck cancer.

The composition for treating cancer of the present invention may further include a pharmaceutically acceptable carrier, and may be formulated together with the carrier.

The term "pharmaceutically acceptable carrier" in the present invention refers to a carrier or diluent that does not stimulate the organism and does not inhibit the biological activity and properties of the administered compound. As a pharmaceutical carrier that is acceptable in a composition formulated as a liquid solution, as a sterile and biocompatible material, saline, sterile water, Ringer's solution, buffered saline, albumin injection solution, dextrose solution, maltodextrin solution, glycerol, ethanol and One or more of these components may be mixed and used, and other conventional additives such as antioxidants, buffers and bacteriostatic agents may be added as necessary. In addition, diluents, dispersants, surfactants, binders, and lubricants may be additionally added to formulate into injectable formulations such as aqueous solutions, suspensions, emulsions, pills, capsules, granules or tablets.

The composition for treating cancer of the present invention can be applied to any formulation containing it as an active ingredient, and can be prepared as an oral or parenteral formulation. The pharmaceutical formulations of the present invention are oral, rectal, nasal, topical (including cheek and sublingual), subcutaneous, vaginal or parenteral; intramuscular and subcutaneous. And intravenous), or forms suitable for administration by inhalation or insufflation.

Formulations for oral administration comprising the composition of the present invention as an active ingredient include, for example, tablets, troches, lozenges, water-soluble or oily suspensions, preparation powders or granules, emulsions, hard or soft capsules, syrups or elixirs. Can be formulated. For formulation into tablets and capsules, formulations such as lactose, saccharose, sorbitol, mannitol, starch, amylopectin, cellulose or gelatin, excipients such as dicalcium phosphate, disintegrants such as corn starch or sweet potato starch, and stearic acid masne It may contain a lubricant such as calcium, calcium stearate, sodium stearyl fumarate, or polyethylene glycol wax, and in the case of capsule formulations, it may further contain a liquid carrier such as fatty oil in addition to the above-mentioned substances.

Formulations for parenteral administration comprising the composition of the present invention as an active ingredient include subcutaneous injections, intravenous injections, intramuscular injections, injectable forms, suppository injection methods, or sprays, such as aerosols that enable inhalation through a respiratory system. It can be formulated as. In order to formulate an injectable formulation, the composition of the present invention may be prepared as a solution or suspension by mixing in water with a stabilizer or a buffer, and formulated for unit administration of ampoules or vials. To inject into a suppository, it can be formulated into a composition for rectal administration such as a suppository or enema containing a conventional suppository base such as cocoa butter or other glycerides. When formulated for spraying, such as aerosols, propellants and the like can be combined with additives to disperse the concentrated dispersion or wet powder.

The composition for treating cancer of the present invention may be injected into a patient's body according to a doctor's prescription or according to a well-known method well known in the art, and a single dose is a disease to be treated, the severity of the disease, and a route of administration. , It can be determined by taking into account several related factors such as the patient's weight, age and gender.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as limited by these examples.

Example 1: Cell line preparation

Breast cancer cell lines HCC1954, MDA-MB-453, and MDA-MB-231 (RPC) from RPMI-1640 (Hyclone, Europe Ltd.) containing 10% FBS, 2 mM L-glutamine, and 100 U / mL Penicillin-Streptomycin Korean Collection for Type Cultures (KCTC). Cells were grown at 37 ° C. in a humidified atmosphere containing 5% CO ₂ . For antibody production, HEK293F cells were maintained in a humidified atmosphere containing 8% CO ₂ at 37 ° C. and grown in Gibco FreeStyle ™ 293 Expression Medium (Thermo Fisher Scientific).

Example 2: Construction of cysteine variants (immunoglobulin variants in which amino acid residues are partially substituted with cysteine)

Example 2-1: Cysteine variant production

The mutation of the antibody heavy chain was introduced using a two-step overlap PCR method, and pcDNA 3.1 (+) containing the Trastuzumab gene was used as a template. The nucleotide sequences of the primers used in the production of cysteine variants are shown in Table 2 (Primer Af: Primer of Trastuzumab gene 5'-end part / Primer Br: Primer of Trastuzumab gene 3'-end part / Primer 1 to 7: cysteine substitution Primer for). The restriction enzyme sites used are NotI and BamHI. Primers A and B are generally used for all production, others were used to make cysteine variants as described in Table 2. For example, the method of changing heavy chain Asparagine 418 to cysteine is as follows: First, PCR reaction was performed using primers Af, primers 1-r, primers Br and primers 1-f, and fragments 1 and 2 were generated. . The two fragments were annealed and used directly for PCR amplification with primers A-f and B-r. The assembled product containing the cysteine mutation was cloned into pcDNA 3.1 (+) using NotI and BamHI. Other cysteine variants are produced as described above.

The amino acid residue number of an antibody herein is in accordance with the Kabat numbering system commonly used in the art (Kabat et al., In “of Proteins of Immunological Interest” 5th Ed., US Department of Health and EU Index number as in Human Services, NIH Publication No. 91-3242, 1991).

Example 2-2: Production and purification of Trastuzumab cysteine variants

Antibodies were generated by transient transfection of expression vectors in HEK293F cells. HEK293F cells were cultured in Gibco FreeStyle ™ 293 Expression Medium (Thermo Fisher Scientific) to prepare at 1 × 10 ⁶ cells / ml. Plasmid DNA was mixed in OptiPro-SFM (Thermo Fisher Scientific) with 7.5 μg / ml polyethylene imine so that the final concentration of each of the heavy and light chains was 1.25 μg / ml. After 15 minutes of incubation, the mixture was added to the cultured cells, and the cells were cultured for 7 days. The supernatant was obtained by centrifugation and filtration to remove impurities. Antibodies were purified with protein A agarose resin (Repligen) as recommended by the manufacturer, and dialyzed against PBS (pH 7.4) through a PD-10 desalting column (GE healthcare).

THIOMAB technology, developed to develop ADCs through engineered Cys residues, is used to bind IgG and proteins in a position-specific manner. Based on US 2015059771, 7 positions of Trastuzumab for the introduction of Cys residues (Q416, N418, N386, N204 G174 in the heavy chain and T197, Q199 in the light chain) were selected and human embryonic kidney cells 293 Freestyle (HEK293F) was used to express 7 engineered Trastuzumab constructs (HC-Q416C, HC-N418C, HC-N386C, HC-N204C, HC-G174C, LC-T197C, LC-Q199C of HC and LC). The highest production yield was HC-N418C (60 mg / L) (Table 3).

Example 2-3: Cysteine position screening introduced into Trastuzumab

Cys residue of the introduced IgG is known to be modified by cysteine or glutathione. To remove blocking groups of modified Cys residues and to create thiol groups for conjugation reactions, each antibody was partially reduced using TCEP, and then re-oxidized using dehydro-ascorbic acid (dhAA). HC-Q416C, N418C and N386C showed reoxidation yields similar to wild-type Trastuzumab (Figure 2), and the number of thiol groups per antibody was close to the ideal value of 2 (Table 4). The remaining four Trastuzumab variants (HC-N204C, HC-G174C, LC-197C, and LC-Q199C) were recalculated less efficiently, which differs from previously reported results (Junutula, JR, et al., Nature biotechnology , 2008. 26 (8): p. 925-932) HC-N418C had higher production yield than HC-Q416C and HC-386C, and the HC-N418C variant was selected as a conjugate with PE24.

Example 3: Preparation of a plasmid for expression of deimmunized Pseudomonas Exotoxin A (PE24)

In the case of deimmunized Pseudomonas exotoxin A, the original PE domain I and domain II were deleted except for the domain II furin cleavage site (aa 274-284). The domain III of the toxin containing seven mutations (R427, R456, D463, R467, R490, R505, R538) was developed by NIH (2014, DOI: 10.1158 / 1535-7163). His 6 tag for affinity chromatography using Ni-NTA and Thrombin cleavage site for His 6 tag removal are introduced into the construct (Fig. 3). The deimmunized exotoxin 24kDa (PE24) gene was synthesized (bioneer Inc.) and PE24 was cloned into the NdeI and NotI sites of pET21a for modified PE expression. As a result, the modified PE coding DNA produced a plasmid with the OmpA secretion signal sequence for the periplasmic fraction at the N-terminus of the construct.

Example 4: Expression and purification of PE24

The PE24 domain containing the azido group responds to amber codon (TAG) using an orthogonal pair of tRNA (CUA) and tyrosyl-tRNA synthetase derived from Methanococcus jannaschii , and azidophenylalanine (AzF) ). The C-terminal sequence of PE24 is important in the metastasis of PE24 to the cytoplasm by inducing toxins into the endoplasmic reticulum after endocytosis. Therefore, the reactive moiety was installed at the N-terminus with a flexible linker. The recombinant protein of the periplasm fraction was purified using a nickel immobilized resin and the His6 purification tag was removed by thrombin reaction. The resulting protein was named PE24-AzF.

The modified PE24 protein is expressed in BL21 cells transformed with three plasmids for the expression of MjAzidophenylalanyl-tRNA synthetase (AzFRs) -MjtRNA orthogonal pair, EcProRS, PE24 protein. After growing the cells in 2XYT medium at 37 ° C. until OD ₆₀₀ became 0.5, the expression of MjAzFRS and EcProRS was induced by adding 0.2% L-arabinose and 50nM anhydrotetracycline, respectively. At OD ₆₀₀ 1.0, 0.2 mM IPTG and 1 mM p-azidophenylalanine were added to express the PE24 protein, followed by incubation at 25 ° C overnight. Cells were harvested by centrifugation at 9,300 × g 4 ° C. for 15 minutes for purification. The harvested cell pellet was resuspended using 0.75M sucrose / 0.1M Tris-HCl (pH 8.0), 10 μl of lysozyme (50 mg / ml) was added and incubated at 4 ° C. for 15 minutes. After 15 minutes of incubation with 1 mM EDTA, 0.5 M MgCl ₂ was added and incubated for 10 minutes. Cells were then recovered by centrifugation (9300 g, 15 min, 4 ° C.), and the supernatant was diluted with 2 × lysis buffer (50 mM sodium phosphate, 300 mM sodium chloride, 20 mM imidazole, pH 7.4). After incubation with Ni-NTA resin (Qiagen) for 1 hour, the supernatant was loaded into a gravity-flow column, and the column was washed with washing buffer (50 mM sodium phosphate, 300 mM sodium chloride, 40 mM imidazole, pH 7.4), and elution buffer. After eluting with (50 mM sodium phosphate, 300 mM sodium chloride, 300 mM imidazole, pH 7.4), thrombin treatment was performed to remove his-tags. The final protein was eluted with lysis buffer using Ni-NTA affinity chromatography.

The expression test of modified PE24 in E. coli was performed to determine whether the protein was expressed in periplasm. SDS-PAGE and Western blot results show that the modified PE24 was almost expressed in periplasm (Fig. 4). The first purification of PE24 from cultured E. coli pellets was performed using Ni-NTA affinity chromatography, showing a soluble protein with a production yield of 6 mg / L. The second tablet to remove His 6 tags through thrombin treatment corresponds to an 80% yield with a yield of 4.8 mg / L (FIG. 5).

Example 5: Conjugation of Trastuzumab cysteine variant with PE24

All steps included buffer exchange with Amicon® Ultra-4 10K Centrifugal Filter device (Millipore). 6 shows a schematic for the combination of Trastuzumab-N418C and PE24. The antibody was removed with a reducing agent tris (2-carboxyethyl) phosphine (TCEP) greater than 100 times (2750 μM) molar in reducing buffer (2 mM EDTA, 50 mM Tris-HCl pH 7.5) for 3 hours at 25 ° C., followed by diafiltration. Remove excess TCEP by. 25 times (172.5 μM), such as Dehydroascorbic acid (dhAA) (Sigma-Aldrich), for 3 hours at 25 ° C. in reoxidation buffer (50 mM Tris-HCl, 150 mM NaCl, pH 7.5) to restore the interchain disulfide bonds of the antibody. Reoxidation was performed by adding an oxidizing agent. Cross-chain disulfide bonds were detected through non-reducing SDS-PAGE, and reactivity of the free thiol group was determined through 4-PDS analysis. More than 40-fold maleimide-PEG-DBCO linker (1100 μM) (Click chemistry Tools) reacted with reoxidized antibody containing reactive cysteine in 25 ° C. PBS (pH 7.4) for 2 hours. The antibody (5 mg / ml) and PE24 (more than 4 times the antibody concentration) were conjugated by reacting at 4 ° C. for 4 hours. The reoxidized HC-N418C was reacted with a DBCO-PEG4-maleimide linker, and then coupled with PE24 through a strain-promoted click reaction between DBCO and azide group.

Although HC-N418 has two binding sites, mainly a single conjugate was formed, and a smaller amount of the double conjugate was observed (lane 5 in FIG. 7). Binding of IgG to PE24 was only detected in the heavy chain where the N418C modification was located, indicating the position-specificity of the binding (lane 8 in FIG. 7).

For reference, the conjugation efficiency of HC-Q416C, HC-N418C, HC-N386C, LCT197C or LC-Q199C trastuzumab variants with PE24-AzF was evaluated. HC-Q416C and HC-N418C variants showed higher conjugation yields than other variants (FIG. 8).

Example 6: Purification of Trastuzumab-PE24 conjugate

Trastuzumab HC-N418C was added to PE24-AzF according to the method described in Example 5 above with a slight modification of the extended time (4 to 16 hours) for the reaction between the two protein molecules to improve yield. Bonded. A two-step purification method consisting of size exclusion and anion exchange chromatography was used to separate the trastuzumab-PE24 conjugate. Unconjugated PE24 and high molecular weight aggregates were removed by size exclusion chromatography and trastuzumab-PE24 was separated according to the number of PEs in the complex using anion exchange chromatography (FIG. 9).

Specifically, trastuzumab-PE24 conjugate was purified by size exclusion chromatography and anion exchange chromatography using Superdex 200 column and Mono-Q column (GE Healthcare). The Superdex 200 column was equilibrated with a running buffer (10mM phosphate, 1M NaCl, pH 7.4). Trastuzumab-PE24 conjugate was injected into the column and eluted with a running buffer to remove unreacted PE24-AzF. Trastuzumab-PE24 conjugate and unconjugated trastuzumab were diluted with 50 ml dilution buffer (10 mM phosphate, pH 7.4) and loaded onto a Mono-Q column equilibrated with buffer A (20 mM phosphate, pH 7.0). Trastuzumab-PE24 was eluted with a gradient of Buffer A and Buffer B (20mM phosphate, 1M NaCl, pH 7.0); 10% to 15% buffer B for trastuzumab conjugated with a single PE24; 15% to 20% buffer B for trastuzumab conjugated with two PE24; 20% to 25% Buffer B for 3 PE24 conjugated trastuzumab.

For the following reasons, a monoconjugated form was used for further characterization: 1) The single conjugated form showed higher yield than the double conjugated form, 2) Toxin per antibody due to the high cytotoxicity of PE Even one molecule is enough to develop an immunotoxin. However, increasing the ratio of PE to IgG to the conjugation reaction was expected to increase the yield of the double conjugation form. SDS-PAGE results of single conjugation under reduced conditions showed that only the HC band shifted by the molecular weight of PE24 (FIG. 9b), indicating that PE24-AzF was conjugated to the HC-N418C site in a position-specific manner. it means.

Example 7: Evaluation of antigen binding affinity to ErbB2 of Trastuzumab-PE24 conjugate using ELISA

The binding of Trastuzumab and Trastuzumab-PE24 to ErbB2 was compared using the ELISA method. ErbB2 binding by Trastuzumab wildtype, HER N418C-PE24 (1), HER N418C-PE24 (2) was evaluated by indirect ELISA.

Microtiter plates were coated with ErbB2 antigen overnight at 4 ° C., coating buffer (PBS pH 7.4, 0.02% sodium azide). After washing, the plates were incubated for 1 hour in blocking buffer (4% skim milk in PBS, pH 7.4) and replaced with 100 μl diluted samples per well. The concentration range of trastuzumab wild type, HER N418C-PE24 (1) and HER N418C-PE24 (2) was 0-100 nM. After the primary incubation with the sample for 1 hour, the unreacted antibody was removed and washed 3 times with 100 μl wash buffer (Tris buffed saline with 0.1% Tween 20). The final buffer was replaced with 100 μL per well with L-HRP conjugate protein diluted 1/500 in blocking buffer, and the plate was incubated for 1 hour at room temperature. Each well was washed 3 times with 100 μl wash buffer. HRP activity was detected with the TMB substrate kit according to the manufacturer's instructions. Briefly, 100 μl of the bound TMB substrate and H2O2 solution were added to each well and incubated at room temperature for 90 seconds. To stop the reaction, 20 μl H ₂ SO ₄ was added, and the absorbance of each well was measured at 450 nm.

The apparent binding affinity of Trastuzumab-PE24 was similar to Trastuzumab (FIG. 10 and Table 5), indicating that binding to PE24 has minimal effect on antibody antigen binding. Since the N418 position located in the CH3 domain is far from the antigen binding site, it is expected that it will not easily interfere with antigen binding. Thus, the retained binding affinity of Trastuzumab-PE24 suggests that the binding strategy used in the present invention does not disturb the structure of Trastuzumab.

Example 8: Confirmation of receptor-mediated endocytosis of the conjugate

Inoculate MDA-MB-231 or MDM-MB-453 cells (4 × 10 ⁴ ) into RPMI 1640 medium containing 10% FBS and 1% penicillin / streptomycin on a coverslip (Marienfeld) in a 24-well plate. , Was grown for 24 hours at 37 ° C. in 5% CO ₂ atmosphere. To bind cells, cells were treated with 200 mM of Trastuzumab or Trastuzumab-PE24 for 30 minutes at 4 ° C., or incubated for additional 4 hours at 37 ° C. to induce the cell's endocytosis pathway. Cells were washed with PBS, fixed with 4% p-formaldehyde for 10 minutes, washed with PBS, 0.1% (w / v) saponin, 0.1% (w / v) sodium azide And permeabilized with PBS containing 1% (w / v) bovine serum albumin (BSA) for 10 minutes. Cells were washed with PBS, blocked with 1% (w / v) BSA for 1 hour, and then exposed to anti-human IgG antibody-Alexa 488 (Thermo Fisher Scientific) for 1 hour. Cell nuclei were stained with Hoechst (Thermo Fisher Scientific) for 10 minutes. Culture and staining were performed at room temperature. The stained cells were examined through a LSM710 confocal microscope equipped with a 63x objective (Carl Zeiss). Images were analyzed using ZEN software (Carl Zeiss).

As a result of the analysis, it was found that conjugation of PE24 to trastuzumab did not affect receptor-mediated endocytosis, the first step in which PE-based immune toxins act on target cells (FIG. 11). The Trastuzumab-PE24 conjugate bound only to Her2-positive MDA-MB-453 cells identical to Trastuzumab (second row in FIG. 11). Further incubation of the cells at 37 ° C. internalized both Trastuzumab and Trastuzumab-PE24 (column 3 in FIG. 11).

Example 9: Confirmation of the effect on the interaction with the Fc receptor

For Fc-related receptor binding assays, 4 μg / ml of Trastuzumab or Trastuzumab-PE24 was coated at 0.05 ° C. Na ₂ CO ₃ pH 9.6 to coat wells of 96-well plates at 4 ° C. overnight. The coated wells were incubated with PBSB at 25 ° C for 1 hour. C1q and FcrRI-His6 were purchased from Abcam and R & D Systems, respectively. As previously known, FcRn-GST, FcrIIa (H) -GST, FcrIIa (V) -GST, FcrIIb-GST, FcrIIIa (F) -GST and FcrIIIa (V) -GST were prepared. After washing the wells three times with PBST, anti-His-HRP conjugate (Sigma-Aldrich) was added to the wells of FcrRI-His6, and anti-GST-HRP conjugate (GE Healthcare) was FcRn-GST, FcrIIa (H) -GST, FcrIIa (V) -GST, FcrIIb-GST, FcrIIIa (F) -GST and FcrIIIa (V) -GST were added, and anti-C1q-HRP conjugate (Sigma-Aldrich) was added to C1q. The plate was incubated at 25 ° C for 1 hour. After washing the wells three times with PBST, TMB substrate was added to each well, and absorbance was measured at 450 nm.

As a result of the analysis, the Trastuzumab-PE24 conjugate was shown to interact with the Fc receptor similar to Trastuzumab (Figure 12 and Table 5). This interaction plays an important role in regulating serum IgG concentration and immune response to pathogens, and thus, can provide additional biological functions to full-length IgG based immunotoxins compared to recombinant immunotoxins with antibody fragments. The conjugation site of HC-N418C is located near the C-terminus of the heavy chain away from the site of interaction with the antigen and Fc receptor. These results indicate that site-specific modification and selection of the conjugation site used to conjugate IgG and PE24 does not interfere with the original function.

Example 10: ADP-ribosylation assay

The cytotoxicity of PE24 was based on ADP-ribosylation of EF2 (FIG. 13), and the enzyme activities of PE24 and Trastuzumab-PE24 were compared. EF2-rich wheat germ extract and PE24 or Trastuzumab-PE24 at various concentrations (0.01 nM, 0.1 nM, 1 nM, 10 nM and 50 nM) were incubated with Biotinylated NAD +, and the reaction mixture was analyzed by Western blot method (FIG. 14).

The ADP-ribosylation activity of the conjugate was determined by measuring the migration of ADP-ribose from Biotinylated NAD + to EF-2 by Zhang and Snyder's method. PE24 and immunotoxin were diluted to the concentrations indicated in 20 mM Tris-HCl (pH 7.4), 1 mM EDTA, 1 mM DTT, and incubated with wheat embryo extract in the presence of 50 nM biotinylated NAD + for 1 hour at 37 ° C. The reaction was terminated with 5x sodium dodecyl sulfate (SDS) gel loading buffer. Protein was isolated from SDS- 12% (w / v) polyacrylamide gel. Biotinylated EF-2 was detected by Western blotting using a streptavidin-horseradish peroxidase (HRP) conjugate. Western blot images were analyzed using the ChemiDoc XRS system.

The Trastuzumab-PE24 conjugate showed activity similar to PE24 (FIG. 14); The molecular weight of EF2 is 95 kDa. These results suggest that binding with Trastuzumab minimally affects the function of PE24. Results regarding antigen binding (FIG. 10) and ADP-ribosylation of EF2 (FIG. 14) indicate that the binding strategy developed in the present invention does not affect the function of the bound molecule, Trastuzumab and PE24.

Example 11: Viability of cells in vitro in various breast cancer cell lines

The cytotoxicity of Trastuzumab-PE24 was evaluated in three breast cancer cell lines (HCC1954, MDA-MB-453, MDA-MB-231). The cytotoxic activity of the conjugate was evaluated using a Cell Counting Kit-8 WST-8 assay (Dojindo Molecular Technologies Inc.,). For cytotoxicity analysis, breast cancer cell lines were inoculated into 96-well plates at 5.0 x 103 cells / well and cultured for 24 hours. Cells were treated with conjugates of various concentrations and then incubated at 37 ° C for 72 hours. WST-8 analytical reagent was added, 96-well plates were incubated at 37 ° C., and absorbance was measured at 450 nm.

HCC1954 and MDA-MB-453 are Her2 / neu positive cell lines, and MDA-MB-231 are Her2 / neu negative cell lines. Each breast cancer cell line was treated with Trastuzumab, PE24 or Trastuzumab-PE24 conjugates in a concentration range of 6.4 pM to 100 nM for 72 hours, and cell viability was measured. In two Her2 / neu positive cell lines (HCC1954 and MDA-MB-453), cytotoxicity of Trastuzumab-PE24 was clearly observed between 6.4 pM and 100 nM (Fig. 15 (a) and Fig. 15 (b)), which is RG7787. It is similar to the previously reported value measured using. On the other hand, Her2 / neu negative cell line (MDA-MB-231) did not show sensitivity to Trastuzumab-PE24 up to 100 nM (Fig. 15 (c)). This means that the conjugate does not affect Her2 / neu negative cell viability, and the specificity of Trastuzumab is maintained in the conjugate.

Example 12: Protein synthesis inhibition assay

The mechanism of action of cytotoxicity of PE24 is the inhibition of protein synthesis by ADP-ribosylation of EF2. To analyze protein synthesis inhibition by trastuzumab-PE24, bio-orthogonal noncanonical amino acid tagging (including tagging of proteins using orthogonal reaction between azide and alkyne groups) by introducing azidohomoalanine (AHA) at the methionine position of the synthetic protein BONCAT) method was used (Dieterich, DC, et al., Proceedings of the National Academy of Sciences, 2006. 103 (25): p. 9482-9487) (Fig. 16).

HCC1954 and MDA-MB-231 cells were inoculated into 24-well plates at 5 x 10 ⁴ cells / well and cultured for 24 hours. Trastuzumab, PE24 and Trastuzumab-PE24 conjugates at 1 nM concentration were treated at 37 ° C. for 20 hours. Cells were washed and incubated for 30 min at 37 ° C. in RPMI 1640 medium without methionine. To label the newly synthesized protein, 4 mM azidohomoalanine (AHA) (click chemistry tools) and cycloheximide (Sigma Aldrich) were added to each well and incubated at 37 ° C. for 2 hours. Cells were washed in cold PBS-MC (1 mM Magnesium chloride and 0.1 mM calcium chloride) to protect the membrane integrity. Cell pellets were obtained by centrifugation (2000 g, 4 ° C., 10 min.) And dissolved by vortexing after adding 1% (w / v) SDS in PBS. The sample was boiled at 95 ° C for 10 minutes and then centrifuged (14000 RPM, 4 ° C, 10 minutes) to obtain a supernatant. To detect protein synthesis inhibition, a click reaction was performed for 1 hour in the dark. Biotinylated cell lysates were detected by Western blotting using a streptavidin-horseradish peroxidase (HRP) conjugate. Proteins with AHA were labeled with Biotin-alkyne and Western blot images were analyzed using the ChemiDoc XRS system.

The negative control ( lanes 3 and 4 in FIG. 17) and the positive control (lane 2 in FIG. 17) using a protein synthesis inhibitor of cycloheximide are the results performed in the same manner as previously reported in the HCC1954 and MDA-MB-231 cell lines. (Hollevoet, K., et al., Molecular cancer therapeutics, 2014. 13 (8): p. 2040-2049; Dieterich, DC, et al., Proceedings of the National Academy of Sciences, 2006. 103 (25): p. 9482-9487).

Trastuzumab-PE24 conjugate inhibited protein synthesis in Her2 / neu positive cell line (lane 5 in FIG. 17 HCC1954), but activity was significantly lower in Her2 / neu negative cell line (lane 5 in FIG. 17 MDA-MB-231). When considered in conjunction with cell viability data, these results indicate that Trastuzumab-PE24 inhibits protein synthesis and results in cell death.

Example 13: Cetuximab-PE24 conjugation and purification of conjugates

To confirm that PE24 can be conjugated in the same manner using other antibodies in addition to trastuzumab, cetuximab-HC-N418 was produced and purified after conjugation with PE24. The conjugation and two-step purification methods described in Example 6 above were used. After reduction, it was confirmed that the internalized disulfide bond of cetuximab was recovered through an oxidation process (FIG. 18A). After conjugation with PE24, only 15 to 19 fractions of the conjugate were purified by size exclusion chromatography (FIG. 18B), which was then purified by anion exchange chromatography to separate and purified according to the number of conjugated PE24 (FIG. 18C). Similar to trastuzumab, conjugates of 6 to 16 fractions conjugated with a single PE24 were also purified when Cetuximab antibody was used.

According to the present invention, the technique of introducing reactive cysteine into a monoclonal antibody using a site-directed mutagenesis and a method of introducing a non-natural amino acid into a protein, the antigen binding and toxin of the antibody Since it does not affect biochemical properties such as catalytic activity, and can produce allogeneic immunotoxins that are cytotoxic to cancer cell lines, various antibody-protein conjugates can be prepared and also applied as a therapeutic agent for cancer.

Since specific parts of the present invention have been described in detail above, it will be apparent to those skilled in the art that this specific technique is only a preferred embodiment, and the scope of the present invention is not limited thereby. will be. Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Electronic file attached.

Claims (21)

1. Method of preparing an immunotoxin (immunotoxin) comprising the following steps:

   (a) reducing and reoxidizing an immunoglobulin variant in which some of the amino acid residues are substituted with cysteine, and then binding with a linker; And

   (b) conjugating the linker-linked immunoglobulin variant with a protein PE24 introduced with unnatural amino acid to generate an immunotoxin.
2. The immunotoxin according to claim 1, wherein the linker-linked immunoglobulin variant and the non-natural amino acid-introduced protein PE24 are linked site-specific by a click reaction. Method of manufacturing.
3. The method of claim 1, wherein the immunoglobulin variant is full-length monoclonal IgG.
4. According to claim 1, wherein the immunoglobulin variant is the 61, 91, 273, 303, 305 amino acids of the heavy chain constant region amino acid sequence represented by SEQ ID NO: 18; The amino acids 61, 91, 272, 302, and 304 of the heavy chain constant region amino acid sequence represented by SEQ ID NO: 22; And a light chain constant region amino acid sequence represented by SEQ ID NO: 20, 91th, 93th amino acids; any one amino acid selected from the group consisting of cysteine is substituted.
5. The method of claim 1, wherein the cysteine substitution is performed through a PCR reaction using a primer.
6. [7] The method of claim 5, wherein the primer is represented by any one or more sequences selected from the group consisting of SEQ ID NO: 1 to 16.
7. The method of claim 1, wherein the reduction is made by using tris (2-carboxyethyl) phosphine (Tris (2-carboxyethyl) phosphine; TCEP).
8. The method according to claim 1, wherein the re-oxidation is performed using dehydroascorbic acid (dhAA).
9. The method according to claim 1, wherein the linker is a maleimide-PEG-DBCO linker.
10. The method of claim 1, wherein the PE24 is deimmunized Pseudomonas Exotoxin A.
11. The method of claim 10, wherein the PE24 is Pseudomonas Exotoxin ( Pseudomonas Exotoxin) A domain Ia is deleted, except for the purine cleavage site (furin-cleavable motif) domain II is deleted, seven mutations (R427A, R456A, D463A, R467A, R490A, R505A and R538A) comprises a domain III of a toxin, and further comprising His 6 tags and a thrombin cleavage site.
12. The method of claim 1, wherein the non-natural amino acid is para-azidophenylalanine (p-azidophenylalanine).
13. The method of claim 1, wherein the immunoglobulin is Trastuzumab or Cetuximab.
14. Immunoglobulin variants in which some of the amino acid residues are substituted with cysteine are immunotoxins that are conjugated with protein PE24 into which unnatural amino acids are introduced via a linker.
15. 15. The method of claim 14, wherein the immunoglobulin variant is 61, 91, 273, 303, 305 amino acids of the heavy chain constant region amino acid sequence represented by SEQ ID NO: 18; The amino acids 61, 91, 272, 302, and 304 of the heavy chain constant region amino acid sequence represented by SEQ ID NO: 22; And a light chain constant region amino acid sequence represented by SEQ ID NO: 20, 91th, 93th amino acids; any one amino acid selected from the group consisting of cysteine is substituted.
16. 15. The immunotoxin of claim 14, wherein the linker is a maleimide-PEG-DBCO linker.
17. 15. The immunotoxin of claim 14, wherein the PE24 is deimmunized Pseudomonas Exotoxin A.
18. The method of claim 17, wherein the PE24 is Pseudomonas Exotoxin ( Pseudomonas Exotoxin) domain Ia is deleted, domain II except for the purine cleavage site (furin-cleavable motif) is deleted, 7 mutations (R427A, R456A, D463A, R467A, R490A, R505A and R538A) comprising a domain III of a toxin, further characterized by the introduction of His 6 tags and Thrombin cleavage site.
19. 15. The method of claim 14, The immunoglobulin is Trastuzumab (Trastuzumab) or cetuximab (Cetuximab), characterized in that the immunotoxin.
20. A composition for the treatment of cancer comprising the immunotoxin according to claims 14 to 19.
21. 21. The composition of claim 20, wherein the cancer is breast cancer, colorectal cancer, non-small cell lung cancer or head and neck cancer.

Images