CN118480117A - Engineered antibodies and antibody-drug conjugates comprising the same - Google Patents

Abstract

Provided herein is an engineered dimeric antibody comprising an antibody Fab as a first Fab domain, a second Fab domain comprising a TCR constant domain, an engineered hinge domain, and an Fc domain having a knob mutation. Also provided are an antibody-drug conjugate comprising the engineered antibody conjugated to one or more drug molecules via a linker, and methods of making the same, compositions comprising the antibody-drug conjugate, and uses thereof in the treatment of diseases, disorders, or conditions.

Description

Engineered antibodies and antibody-drug conjugates comprising the same

Technical Field

The present invention relates generally to the field of biopharmaceuticals, and in particular to engineered antibodies and antibody-drug conjugates.

Background

Antibodies are multifunctional immunoglobulins with unique binding specificity for a target antigen and a range of non-antigen dependent immune interactions, thereby playing an important role in the immune system. Many therapeutic biological agents, diagnostic agents and research agents currently in use are antibodies directed against antigens associated with the pathology, immune mechanism or biological mechanism of interest.

In recent years, there have been a great deal of effort to develop drug-loaded antibody conjugates. In the case of Antibody Drug Conjugates (ADCs), the ADC comprises an antibody for targeting, a linker for drug attachment and a potent drug load as effector. The antibodies or related forms thereof carry the cytotoxic drug to the antigen-expressing cells or other target cells via antibody-antigen interactions. Meanwhile, toxicity is obviously reduced after the drug is coupled with the antibody. Thus, ADCs expand the therapeutic window by lowering the Minimum Effective Dose (MED) and increasing the Maximum Tolerated Dose (MTD). FDA approved ADC drugs are, for example Mylotarg, adcetris, kadcyla, besponsa, polivy, padcev, enhertu, trodelvy and Blenrep.

The success of ADC development depends on the choice of antibody, the choice of linker-drug load, the way the linker-drug load is coupled, and the development of the coupling process. Cysteine sulfhydryl groups in antibodies are ideal coupling reactive groups as strong nucleophiles. In the natural form of an antibody, cysteine residues exist in disulfide form, and therefore, the reduction of disulfide bonds between the light and heavy chains of an antibody to coupling provides the desired free cysteine sulfhydryl groups. To address the related opportunities and challenges of preferred drug load-to-antibody ratios (PAR) and conjugation sites, a variety of conjugation methods have been developed in the art. Ideally, an appropriate amount of drug load should be attached to the antibody, resulting in a heterogeneous ADC product. Coupled products with low PAR have insufficient curative effect, while products with high PAR have high toxicity and instability. Therefore, the heterogeneity of ADCs prevents the expansion of the therapeutic window. Accordingly, efforts such as antibody engineering have been made to improve the homogeneity of ADC products.

One approach employs point mutations in antibodies to introduce amino acids with highly reactive residues for coupling. Thiomab ^TM technology was developed by genetec (Genentech) and by inducing cysteine mutations in antibodies (Jagath R Junutula, et al, conjugation of cytotoxic drugs to antibody site-specific conjugation improved therapeutic index (Site-specific conjugation of a cytotoxic drug to an antibody improves the therapeutic index),Nature Biotechnology,2008,26(8):925–932). and Thiomab occurs at the reduced engineered cysteine residues, yielding highly homogeneous conjugation products. Unnatural amino acid (NNAA) technology is also used to produce homogeneous conjugates e.g., the introduction of keto or azido groups in antibodies as coupling sites with unnatural amino acids (Jun y. Axup, et al, using unnatural amino acid synthesis site-specific antibody-drug conjugate (Synthesis of site-specific antibody-drug conjugates using unnatural amino acids),PNAS,2012,109(40):16101-16106;Michael P.VanBrunt,, et al, genetically encoding azides containing amino acids in mammalian cells, using click cycloaddition chemistry enabled site-specific antibody-drug conjugate (Genetically Encoded Azide Containing Amino Acid in Mammalian Cells Enables Site-Specific Antibody–Drug Conjugates Using Click Cycloaddition Chemistry),Bioconjugate Chem.,2015,26(11):2249-2260), to be highly homogeneous due to specific reactions also resulted in highly homogeneous products.

There are several disadvantages to the point mutation based approach. First, the mutation sites need to be carefully selected, otherwise both the stability and binding efficiency of the antibody are affected. Second, the expression level of point mutated antibodies is typically low, which can be problematic during the chemical component production and control (CMC) stage.

Another approach is to introduce a short polypeptide tag that is recognizable by the enzyme as a coupling site. Glutamine tag (LLQG) acts as a mTG recognition motif (Pavel Strop et al, "importance of site: binding site modulates stability and pharmacokinetics of antibody drug conjugate (Location Matters:Site of Conjugation Modulates Stability and Pharmacokinetics of Antibody Drug Conjugates)",Chemistry&Biology,2013,20(2):161-167),LPETG as a sortase A recognition motif (Roger R.Beerli et al," sortase mediates formation of highly potent site-specific antibody drug conjugates (Sortase Enzyme-Mediated Generation of Site-Specifically Conjugated Antibody Drug Conjugates with High In Vitro and In Vivo Potency)",PLOS ONE,2015,10(7):e0131177)、 and LCxPxR in vitro as Formylglycine Generating Enzyme (FGE) recognition motifs (Peng Wu et al, "recombinant protein (Site-specific chemical modification of recombinant proteins produced in mammalian cells by using the genetically encoded aldehyde tag)",PNAS,2009,106(9):3000-3005) chemically modified with a genetically encoded aldehyde tag generated site-specific in mammalian cells for conjugation yields a highly homogeneous product in which the drug is linked to the polypeptide tag).

The disadvantages of short polypeptide tags are similar to those based on point mutation. It is desirable to screen for insertion sites for polypeptide tags, and the available sites for polypeptide tags are limited. Furthermore, the titer of expression of labeled antibodies is also a difficulty when using this strategy.

The most straightforward method of producing antibody conjugates is to use the thiol group of a natural cysteine in the antibody heavy and light chain polypeptides. The sulfhydryl is used as a strong nucleophilic reagent, and can realize rapid and efficient coupling reaction in water phase. In FDA approved ADC drugs such as Adcetris and Polivy, MMAE is coupled to cysteine residues generated by partial reduction of interchain disulfide bonds by reaction of the thiol group on the cysteine residue with a maleimide group in the linker for monomethyl auristatin E (MMAE). Partial reduction is preferred here rather than complete reduction because the hydrophobicity of the drug and steric hindrance when all cysteine residues are linked results in the ADC drug being unstable in plasma. However, the product obtained after partial reduction has poor homogeneity, which makes CMC difficult, especially for the control of the coupling process and QC standard analysis. On the other hand, substances with different DAR in the ADC mixture show different stability and efficacy in vivo, which means that not all substances in heterogeneous ADC products conform to the intended structural pattern.

The IgG subclasses IgG1, igG2, igG3 and IgG4 share many similarities and differences in disulfide bond structure. Taking IgG1 and IgG4, which are most commonly used as therapeutic biologies, as an example, both heavy chains of IgG1 and IgG4 are linked by two disulfide bonds and there are a total of 12 intrachain disulfide bonds; however, the light chain of IgG1 is linked to the heavy chain by a disulfide bond between its last residue and the fifth cysteine residue of the heavy chain, while the light chain of IgG4 is linked to the heavy chain by a disulfide bond between its last cysteine residue and the third cysteine residue of the heavy chain. Generally, the solvent exposure levels of intra-and inter-chain disulfide bonds are different. The intrachain disulfide bonds are all buried between the secondary structures of the individual domains and are not exposed to solvents. The interchain disulfide bonds located in the hinge region are highly exposed to solvents, including the heavy-heavy interchain disulfide bonds of IgG1 and IgG4 and the heavy-light interchain disulfide bonds of IgG 1. The IgG4 heavy chain-light chain inter-disulfide bond is located between the VH and CH1 domain interfaces that are less accessible and therefore has less contact with solvents. Solvent exposure differences between different disulfide bonds have a significant impact on the bioconjugation of antibodies, as exposed cysteine residues are believed to be more reactive than unexposed cysteine residues (Hongcheng Liu & Kimberly May, disulfide bond structure of IgG molecules: structural changes, chemical modifications, and possible effects on stability and biological function (Disulfide bond structures of IgG molecules:Structural variations,chemical modifications and possible impacts to stability and biological function),Mabs,2012,4(1):17-23). have been shown to be strongly reactive for both heavy-light and heavy-heavy inter-chain disulfide bonds of IgG 1.

The hinge region is a flexible linker between the antibody Fab and Fc. The hinge region varies widely in length and flexibility between the IgG subclasses IgG1, igG2, igG3 and IgG 4. Taking the most commonly used therapeutic biologicals as examples, igG1 and IgG4, the hinge region of IgG1 is 15 amino acids, is very flexible, the hinge region of IgG4 is shorter, only 12 amino acids (Gestur Vidarsson, et al, subclasses and allotypes of IgG: structure to effector function (IgG subclasses and allotypes: from structure to effector functions), front. Immunol.,2014,5: 520). Wild-type IgG1 and IgG4 differ by one amino acid in the core hinge region (EU numbering 226-229): cys-Pro-Pro-Cys in IgG1 and Cys-Pro-Ser-Cys in IgG 4. The natural IgG4 has a balance between interchain and intrachain cysteine disulfide bonds at the core hinge region, so that the presence of IgG4 half-antibody molecules following heavy chain arm exchange and secretion can be observed. It has been demonstrated that the S228P mutation of IgG4 prevents natural arm exchange to significantly stabilize covalent interactions between IgG4 heavy chains (S.Angal et al, "single amino acid substitution eliminates the heterogeneity (A single amino acid substitution abolishes the heterogeneity of chimeric mouse/human(IgG4)antibody)",Molecular Immunology,1993,30(1):105-108;John-Paul Silva etc. of chimeric mouse/human (IgG 4) antibodies," novel quantitative immunoassay in combination with physiological matrix preparation demonstrated that the S228P mutation prevents in vivo and in vitro IgG4 Fab arm exchange (The S228P Mutation Prevents in Vivo and in Vitro IgG4 Fab-arm Exchange as Demonstrated using a Combination of Novel Quantitative Immunoassays and Physiological Matrix Preparation)",Journal of Biological Chemistry,2015,290(9):5462-5469), and has thus been widely used in the development and production of IgG4 antibodies S228P mutation forms a multiproline helix (5 Pro in the lower hinge region) in the IgG4 hinge, with a shorter hinge length of IgG4, further limiting its flexibility compared to the IgG1 hinge (3 Pro in the lower hinge region). Flexible differences between different hinges are of great significance for biological coupling of antibodies, as cysteine residues in flexible hinge fragments are considered to be more reactive than cysteine residues in rigid hinges.

A disadvantage of using native cysteine for antibody conjugation is that the similarity in reactivity between the four interchain disulfide bonds in IgG1 and IgG4 results in highly heterogeneous conjugation products. As previously mentioned, this heterogeneity reduces the therapeutic window of coupled drugs for clinical use. For example, ADCs produced by partial reduction of native interchain disulfide bonds in IgG1 antibodies can produce a product mixture with a normal distribution. The product heterogeneity of partially reduced IgG4 antibodies is even higher, while at very high levels of fully reduced antibodies there are still many antibodies that have not been reduced.

WuXiBody ^TM (hereinafter also referred to as "WuXiBody") is an innovative bispecific antibody (dual antibody (bsAb) platform developed by the pharmaceutical organism (WuXi Biologics) its main feature is the replacement of the CH1/CL constant domain in the antibody Fab domain with the T Cell Receptor (TCR) constant domain, as described in PCT application PCT/CN2018/106766 (international publication WO 2019/057122). WuXiBody ^TM design ensures homologous HC-LC pairing. WuXiBody based bsAb can take an asymmetric form or can take a symmetric form.heterodimerization can be ensured by "pestle" ("KIH") technology.

Nevertheless, there remains a need to improve the PAR of antibody bioconjugates, in particular for therapeutic applications, so as to eliminate as much as possible part or all of the above-mentioned drawbacks.

Disclosure of Invention

The present disclosure provides engineered antibodies comprising a Fab domain having a TCR constant domain as in WuXiBody ^TM, an engineered hinge region, and an Fc domain having a KIH mutation. Surprisingly, ADCs produced with such engineered antibodies have high homogeneity and well controlled DAR. These ADCs advantageously feature high stability and excellent therapeutic effects.

In a first aspect, provided herein is an engineered dimeric antibody, wherein a first monomer comprises a first Fab domain and a first engineered hinge region operably linked thereto and a first Fc region operably linked thereto thereafter, and a second monomer comprises a second Fab domain and a second hinge region operably linked thereto and a second Fc region operably linked thereto thereafter;

Wherein the first Fab domain is an antibody Fab domain and the second Fab domain comprises a fusion

An antibody Fv domain that is synthetic to a TCR constant domain; and

Wherein the first engineered hinge region is comprised of a truncated IgG1 hinge region portion and a truncated IgG4 hinge region portion or is a modified IgG4 hinge region, whereby the first engineered hinge region is coupled to the second hinge region and the hinge domain comprised thereof comprises at least two interchain disulfide bonds; and is also provided with

Wherein the first Fc region is coupled to the second Fc region and the Fc domain comprised thereof comprises a knob-to-hole mutation.

In another aspect, provided herein is a nucleic acid molecule or combination of nucleic acid molecules encoding an engineered antibody of the invention.

In another aspect, provided herein are antibody-drug conjugates comprising an engineered antibody of the invention coupled to one or more drug molecules via a linker.

In another aspect, provided herein is a composition comprising or consisting of a mixture of an antibody-drug conjugate of the invention, wherein the drug/antibody ratio of the antibody-drug conjugate is 2 (DAR 2) of at least about 65%, preferably at least about 70%, at least about 75%, at least about 80%, or at least about 90%.

In another aspect, provided herein is a product comprising or consisting of a mixture of an antibody-drug conjugate of the invention, wherein the drug/antibody ratio of the antibody-drug conjugate is 6 (i.e., DAR 6) of at least about 80%, preferably at least about 85%, or at least about 90%.

In another aspect, provided herein is a pharmaceutical composition comprising an antibody-drug conjugate of the invention and a pharmaceutically acceptable carrier.

In another aspect, provided herein is a method of making an antibody-drug conjugate of the invention comprising coupling a partially reduced antibody of the invention to a linker-drug cargo compound having a maleimide or haloacetyl moiety via a Michael addition reaction.

In another aspect, provided herein is an antibody-drug conjugate product obtained by the method of the invention comprising or consisting of a mixture of the antibody-drug conjugates of the invention, wherein the drug/antibody ratio of at least about 65%, preferably at least about 70%, at least about 75%, at least about 80%, or at least about 90% of the antibody-drug conjugates is 2.

In another aspect, provided herein is an antibody-drug conjugate product obtained by the method of the invention comprising or consisting of a mixture of antibody-drug conjugates of the invention, wherein the drug/antibody ratio of at least about 80%, preferably at least about 85%, at least about 90% of the antibody-drug conjugates is 6.

In another aspect, provided herein is a method of treating a disease, disorder, or condition in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of an antibody drug conjugate of the invention. The disease may be cancer.

In yet another aspect, provided herein are antibody-drug conjugates of the invention for use in treating a disease, disorder or condition in a subject in need thereof. The disease may be cancer.

The present invention has several advantages. The resulting engineered antibodies are less immunogenic in vivo due to the use of native immunoglobulin G hinge sequences and the exchange that occurs at their native structural positions without introducing any entirely new amino acid sequences. Furthermore, the engineered antibody of the present invention can obtain a protein expression titer corresponding to the reference for IgG1 or IgG 4. Furthermore, the engineered antibodies of the invention enable highly homogeneous DAR controlled good ADC products.

The production of the antibody-drug conjugate of the invention can be significantly simplified and can be a simple (one-pot) conjugation process comprising: partial reduction is first carried out with mild reducing agents and then coupling is carried out in the same buffer. The ADC products of the invention have a highly homogeneous well-controlled DAR, e.g., a percentage of DAR type 2 of over 90% or a percentage of DAR type 6 of over 87%. In addition, the ADC of the invention has excellent in vitro and in vivo stability.

Other objects, features and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Drawings

The accompanying drawings are included to provide a further understanding of the invention. The following detailed description of one or more drawings and detailed description of the invention is presented to aid in the understanding of the invention.

Fig. 1: schematic representation of the engineered antibodies of the invention and schematic representation of the use of the antibodies to produce ADCs with DAR2 or DAR6 as the major product.

FIG. 2 shows the structure of antibody 886-39 and its HIC-HPLC results coupled with MC-vc-PAB-MMAE. DAR2 is the major product as shown by HIC-HPLC results.

FIG. 3 shows LC-MS characterization results of 886-39-MMAE-DAR 2. Based on the measured abundance of the binding drug molecule on the light chain and the measured abundance of the binding drug molecule on the heavy chain, most of the drug molecule is loaded on the antibody Fab domain and no drug is loaded on the TCR constant domain.

FIG. 4 shows the structure of antibody 886-39 and its HIC-HPLC results coupled with MC-vc-PAB-MMAE. DAR6 is the major product as shown by HIC-HPLC results.

FIG. 5 shows LC-MS characterization results of 886-39-MMAE-DAR 6. As shown by LC-MS results, no drug was loaded in the TCR constant domain.

FIG. 6 shows the structure of antibody 886-40 and its HIC-HPLC results coupled with MC-vc-PAB-MMAE. DAR2 is the major product as shown by HIC-HPLC results.

FIG. 7 shows LC-MS characterization results of 886-40-MMAE-DAR 2. Based on the measured abundance of the binding drug molecule on the light chain and the measured abundance of the binding drug molecule on the heavy chain, most of the drug molecule is loaded on the antibody Fab domain and no drug is loaded on the TCR constant domain.

FIG. 8 shows the structure of antibody 886-40 and its HIC-HPLC results coupled with MC-vc-PAB-MMAE. DAR6 is the major product as shown by HIC-HPLC results.

FIG. 9 shows LC-MS characterization results of 886-40-MMAE-DAR 6. As shown by LC-MS results, no drug was loaded in the TCR constant domain.

FIG. 10 shows the structure of antibody 886-41 and its HIC-HPLC results coupled with MC-vc-PAB-MMAE. DAR2 is the major product as shown by HIC-HPLC results.

FIG. 11 shows LC-MS characterization results of 886-41-MMAE-DAR 2. Based on the measured abundance of the binding drug molecule on the light chain and the measured abundance of the binding drug molecule on the heavy chain, most of the drug molecule is loaded on the antibody Fab domain and no drug is loaded on the TCR constant domain.

FIG. 12 shows the structure of antibody 886-41 and its HIC-HPLC results coupled with MC-vc-PAB-MMAE. DAR6 is the major product as shown by HIC-HPLC results.

FIG. 13 shows LC-MS characterization results of 886-41-MMAE-DAR 6. As shown by LC-MS results, no drug was loaded in the TCR constant domain.

Fig. 14: the light and heavy chain sequences of the exemplary antibodies are shown with the variable region in bold, KIH mutant residues in bold, and the engineered hinge region underlined. Where "LC" refers to the monomeric Light Chain (LC) comprising the antibody Fab domain, "TCR-LC" refers to the monomeric Light Chain (LC) comprising the TCR constant domain in the Fab domain, "TCR-HC-pestle" refers to the Heavy Chain (HC) comprising the pestle mutation in the Fc region, and "HC-mortar" refers to the Heavy Chain (HC) comprising the mortar mutation in the Fc region.

Definition of the definition

As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Also, the terms "a", "an" or "a plurality of" and "at least one" are used interchangeably herein.

Ordinal numbers such as "first," "second," "third," "fourth," etc., do not denote a requirement of order or relativity, but rather are each directed to a plurality of separate entities or components for convenience and clarity, unless the context clearly indicates otherwise.

Herein, the term "about" or "approximately" refers to an amount, level, value, number, frequency, percentage, dimension, size, amount, weight, or length that differs by at most 30%, 25%, 20%, 25%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1% relative to a reference amount, level, value, number, frequency, percentage, dimension, size, amount, weight, or length. In particular embodiments, the term "about" or "approximately" when preceded by a numerical value indicates a range of 15%, 10%, 5%, or 1% of the value.

Herein, the term "substantially free" with respect to the presence of a certain condition or substance means not only absent (i.e., "none", "zero", etc.) but also presence or amount that is not significant or below the limit of examination and thus cannot be detected. This is well known to those skilled in the art.

Herein, the term "exemplary" means "serving as an example, instance, or illustration. Any matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects.

The terms "comprising," "including," "characterized by …," and "having," and grammatical variants thereof, are used interchangeably herein and should be taken to include the explicit steps or elements without excluding any other steps or elements. Thus, they include exclusive inclusion, as represented by the closed term "consisting of …" and grammatical variants thereof, and semi-closed inclusion, as represented by the term "consisting essentially of …," which is open to only elements that are not important in quality and/or quantity.

One or more features of one embodiment herein may be combined with one or more features of another embodiment without departing from the spirit and concepts of the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The publications and patent documents cited herein are incorporated by reference and are suitable for all purposes. References cited in this specification should be considered as a technical level of skill in the art, but it should not be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention.

Herein, the term "antibody" encompasses any immunoglobulin, monoclonal antibody, polyclonal antibody, multispecific antibody, or bispecific (bivalent) antibody that binds to one or more particular antigens. Typically, an antibody, like a naturally intact antibody, comprises two heavy chains and two light chains. Each heavy chain comprises a variable region ("VH") and first, second, third constant regions (CH 1, CH2, CH 3) and a conditional fourth constant region (CH 4), as is the case for IgM and IgE antibodies, while each light chain consists of a variable region ("VL") and a constant region (CL). Mammalian heavy chains are classified as alpha, delta, epsilon, gamma and mu types, while mammalian light chains are classified as lambda and kappa types. The variable regions of the light and heavy chains are responsible for antigen binding. Each variable region typically comprises three highly variable loops, known as "Complementarity Determining Regions (CDRs)". The boundaries of the CDRs may be defined or identified by rules of Kabat, chothia or Al-Lazikani. The three CDRs are inserted between Framework Regions (FR) flanking them, which are highly conserved compared to the CDRs and form a scaffold that supports the hypervariable loops. The constant regions of the heavy and light chains do not participate in antigen binding, but exhibit multiple effector functions. The main five classes of antibodies are IgA, igD, igE, igG and IgM, which are characterized by heavy chains of the alpha, delta, epsilon, gamma and mu types, respectively. Several major antibody classes are divided into subclasses, such as IgG1 (gamma 1 heavy chain), igG2 (gamma 2 heavy chain), igG3 (gamma 3 heavy chain), igG4 (gamma 4 heavy chain), igA1 (alpha 1 heavy chain) or IgA2 (alpha 2 heavy chain). Thus, in the present invention, a particular IgG type, e.g. "IgG1 type" or "IgG1 type", refers to each IgG isotype of a given subclass, while a different IgG type refers to an IgG isotype of a different subclass.

Herein, by "variable region" in reference to an antibody is meant an antibody variable region or fragment thereof comprising one or more CDRs. Although the variable region may comprise an intact variable region (e.g., VH or VL), it may be a variable region that is not sufficiently intact while still retaining the ability to bind to an antigen or form an antigen binding site.

The antibody may be "Y" shaped, with two arms also referred to as "antigen binding fragments (Fab)", and the stem portion comprising the hinge and Fc domains of the antibody.

The terms "Fab", "Fab domain" and "Fab arm" are used interchangeably to refer to the domain of an immunoglobulin (e.g., an antibody) in which the light chain is coupled to the heavy chain in the variable region and the first constant region. In general, the Fab domain may comprise one or more interchain disulfide bonds. In some embodiments, the constant regions of the light and heavy chains may be replaced with TCR constant regions. Fab domains are responsible for a variety of antigen binding activities.

As used herein, the "Fc region" refers to a fragment consisting of the second constant region (CH 2) of the heavy chain and thereafter, or a fragment consisting of a portion of the hinge region, the second constant region (CH 2) of the heavy chain and thereafter. Also, herein, the "Fc domain" of a dimeric antibody refers to the portion of the coupled heavy chain where the Fc region of each chain is located. The Fc region has a variety of effector functions, such as ADCC and CDC.

As used herein, the "hinge" or "hinge region" of a heavy chain refers to the region connecting the C-terminus of the CH1 region and the N-terminus of the CH2 region of the heavy chain. The hinge region may be about 12-62 amino acid residues in length. In human IgG1, the hinge region comprises residues 216 to 230 and in human IgG4 comprises residues 219 to 230, numbered according to EU. As used herein, the "hinge domain" of a dimeric antibody refers to the portion of the coupled heavy chain where the hinge region of each chain is located. Typically, the hinge domain may comprise one, two or more interchain disulfide bonds. The hinge region is flexible to allow for the movement of each of the two Fab domains.

The hinge region is the flexible linking region between the antibody Fab and Fc. The hinge region varies widely in length and flexibility between the IgG subclasses IgG1, igG2, igG3 and IgG 4. Taking the most commonly used therapeutic biologicals as IgG1 and IgG4, the hinge region of IgG1 comprises 15 amino acids (e.g., EPKSCDKTHTCPPCP (SEQ ID NO: 9)), is flexible, and the hinge region of IgG4 is shorter, only 12 amino acids. Wild-type IgG1 and IgG4 differ by one amino acid in the core hinge region (EU numbering 226-229): cys-Pro-Pro-Cys in IgG1 and Cys-Pro-Ser-Cys in IgG 4. The core hinge region of native IgG4 has a balance between interchain and intrachain cysteine disulfide bonds, and thus heavy chain arm exchange and secretion occurs followed by the presence of IgG4 half-antibody molecules. It has been demonstrated that the S228P mutation of IgG4, such as ESKYGPPCPPCP (SEQ ID NO: 10), can significantly stabilize covalent interactions between IgG4 heavy chains by preventing natural arm exchange, and thus has been widely used in the development and production of IgG4 antibodies. The S228P mutation forms a polyproline helix in the IgG4 hinge (PPCPPCP), which, in combination with the shorter IgG4 hinge length, further limits its flexibility compared to the IgG1 hinge. The difference in flexibility between the different hinges is of importance for the bioconjugation of antibodies, as the cysteine residues located in the flexible hinge fragments are considered more reactive than the cysteine residues located in the rigid hinges. Experiments have shown that both the heavy-light chain and heavy-heavy chain inter-disulfide bonds of S228P IgG4 are weakly reactive.

As used herein, the "CH2 domain" refers to the portion of the heavy chain molecule where amino acids 244 to 360 (amino acids 244 to 360, amino acids 231 to 340, numbering in Kabat), are located in IgG antibodies according to conventional numbering schemes.

The "CH3 domain" extends from the CH2 domain of an IgG molecule to the C-terminus, and comprises about 108 amino acids. Certain immunoglobulins (e.g., igM and IgE) also contain a CH4 region.

"Fv", "Fv fragment" and "Fv domain" are used interchangeably and refer to the smallest domain that contains the complete antigen binding site of an antibody. Fv domains generally comprise a light chain variable region (VL) and a heavy chain variable region (VH) coupled to one another.

Percent (%) identity between biological sequences (including amino acid sequences and nucleic acid sequences) refers to the percentage of identical residues between the sequence under investigation and the reference sequence when aligned for maximum matching. Sequence identity can be determined using public tools such as BLASTN, BLASTp (available on the National Center for Biotechnology Information (NCBI) website), clustalW2 (available on the European bioinformatics institute website), and ALIGN or Megalign (DNASTAR) software.

Herein, "specific binding" or "specifically binding" refers to a non-random binding reaction between two molecules (e.g., between an antibody and an antigen). In some embodiments, the engineered antibodies provided herein can specifically bind antigen with a binding affinity (K _D)≤10^-6 M (e.g., ≤5x10^-7 M、≤2x10^-7 M、≤10^-7M、≤5x10^-8 M、≤2x10^-8 M、≤10^-8M、≤5x10^-9 M、≤2x10^-9 M、≤10^-9M or +.10 10 ^-10 M). K _D herein refers to the ratio of the rate of dissociation to the rate of association (K _off/k_on).

"Operably linked" refers to two or more biological sequences of interest being juxtaposed with or without a spacer or linker therebetween in a manner such that their relationship permits each to function in the intended manner. By polypeptide is meant that the polypeptide sequences are linked in such a way that the linked product has the intended biological function. For example, the antibody variable region may be operably linked to a constant region to provide a stable product having antigen binding activity. The term may also be used to describe polynucleotides. For example, a polynucleotide encoding a polypeptide is operably linked to a regulatory sequence (e.g., a promoter, enhancer, silencer sequence, etc.) when such polynucleotide sequences are linked in such a way that the polynucleotide is capable of expressing the polypeptide under control.

Sequences that are not 100% identical to the reference sequence may contain mutations at one or more positions, which may be substitutions, additions, deletions, or combinations thereof. Substitutions may be "conservative substitutions", meaning substitutions with different amino acids of similar physicochemical properties of the side chains, or at sites that are not important to the activity or function of the sequence. For example, conservative substitutions may be between amino acids having nonpolar side chains (e.g., met, ala, val, leu and Ile, pro, phe, trp), between amino acids having uncharged polar side chains (e.g., cys, ser, thr, asn, gly and Gln), between amino acids having acidic side chains (e.g., asp, glu), between amino acids having basic side chains (e.g., his, lys, and Arg), between amino acids having beta-branched side chains (e.g., thr, val, and Ile), between amino acids having sulfur-containing side chains (e.g., cys and Met), or between amino acids having aromatic side chains (e.g., trp, tyr, his and Phe). Conservative substitutions do not cause significant changes in conformational structure and thus can preserve the biological activity of the protein.

Herein, "subject" refers to a human or non-human animal. The non-human animal may be a mammal, such as a primate. Examples of non-human mammalian subjects include, but are not limited to, domestic, farm and zoo animals, athletic or pet animals, such as dogs, cats, guinea pigs, rabbits, rats, mice, horses, pigs, cattle and bears. Preferably, the subject is a human. A "subject in need thereof" refers to a subject in need of diagnosis, prognosis, alleviation, prevention and/or treatment of a disease, disorder or condition.

Detailed Description

The following description is merely illustrative of the various embodiments herein. Therefore, specific modifications, changes, etc. discussed herein should not be construed as limiting the scope of the disclosure herein. It will be apparent to those skilled in the art that various equivalents, modifications, and alterations can be made within the scope of the disclosure herein, and it is intended that such equivalents be included within the scope herein. All references, including publications, patents, and patent applications, cited herein are hereby incorporated by reference in their entirety.

Engineered antibodies

In one aspect, provided herein is an engineered dimeric antibody, wherein a first monomer comprises a first Fab domain, a first engineered hinge region operably linked thereto, and a first Fc region operably linked thereto, and a second monomer comprises a second Fab domain, a second hinge region operably linked thereto, and a second Fc region operably linked thereto;

Wherein the first Fab domain is an antibody Fab domain and the second Fab domain comprises an anti-Fab domain

A bulk Fv domain and a TCR constant domain fused thereto; and

Wherein the first engineered hinge region consists of a truncated IgG1 hinge region portion and a truncated IgG4 hinge region portion or is a modified IgG4 hinge region, the hinge domain formed by coupling the first engineered hinge region to the second hinge region comprising at least two interchain disulfide bonds; and is also provided with

Wherein the Fc domain formed by coupling the first Fc region to the second Fc region comprises a knob-to-socket mutation.

In some embodiments, the engineered antibodies of the invention may be as shown in the schematic of fig. 1, wherein the TCR constant domains are represented as a pair of rectangles. Monomers are coupled to form dimer antibodies by inter-chain binding forces, including inter-chain bonds and/or inter-chain interactions. Examples of inter-chain binding forces include, but are not limited to, disulfide bonds, hydrogen bonds, electrostatic interactions, salt bridges, hydrophobic-hydrophilic interactions, and the mortar (Knobs-into-Holes) mechanism. The engineered antibodies of the invention are heterodimers.

For the engineered antibodies of the invention, an "antibody Fab domain" meets the standard meaning commonly understood by those skilled in the art and refers to a Fab domain having the structure and function typical of Fab domains in known antibody immunoglobulins. The present invention is also to be understood simply as not containing the classical Fab domain which replaces the constant domain with the TCR constant domain using WuXiBody ^TM technology.

In the present invention, the antibody Fab domain may be a Fab domain derived from any antibody, particularly those for clinical use. In some embodiments, the antibody Fab domain is derived from an antibody that specifically binds to a Tumor Antigen (TA), such as a Tumor Specific Antigen (TSA) and a Tumor Associated Antigen (TAA). Examples of tumor antigens include, but are not limited to, ：CD20、CD38、CD123、ROR1、ROR2、BCMA、PSMA、SSTR2、SSTR5、CD19、FLT3、CD33、PSCA、ADAM 17、CEA、Her2、EGFR、EGFR-vIII、CD30、FOLR1、GD-2、CA-IX、Trop-2、CD70、CD38、 mesothelin, ephA2, CD22, CD79b, GPNMB, CD, CD138, CD52, CD74, CD30, CD123, RON, and ERBB2. Examples of TA-specific antibodies include, but are not limited to: trastuzumab (Trastuzumab), rituximab (Rituximab), cetuximab (Cetuximab), bevacizumab (Bevacizumab), panitumumab (Panitumumab), alemtuzumab (Alemtuzumab), matuzumab (Matuzumab), gemtuzumab (Gemtuzumab), poisotoizumab (Polatuzumab), itumomab (Inotuzumab), and the like.

In the second Fab domain, the antibody Fv domain is fused to the TCR constant domain according to WuXiBody ^TM described in PCT/CN 2018/106766. Specifically, the heavy chain variable region (VH) is fused to a TCR constant region, and the light chain variable region (VL) is fused to another TCR constant region. For the engineered antibodies of the invention, the "antibody Fv" domain refers to the Fv domain of the antibody Fab described above. The first Fab domain and the second Fab domain of the engineered antibodies of the invention may have the same or different binding specificities.

In the second monomer, the TCR constant domain may consist of a pairing of the cα and cβ regions or a pairing of the cγ and cδ regions of the TCR. In some embodiments, the TCR constant domain is a cαβ constant domain. In some embodiments, the second monomer is WuXiBody ^TM antibody half-antibody comprising a TCR constant domain. Although TCR constant domains also have interchain disulfide bonds, their reduction reactivity is much lower, so drug coupling is more difficult than interchain disulfide bonds of antibody Fab domains. The present invention takes advantage, at least in part, of this difference in reduction reactivity, thereby achieving ADC production with high homogeneity and better DAR control.

In some embodiments, the antibody Fab domain is a Fab domain of an IgG1 antibody, i.e., a Fab domain of the IgG1 type. Preferably, the antibody Fab domain is a human IgG1 antibody Fab domain. In some embodiments, the Fv domain is an Fv domain of an IgG antibody, i.e., an Fv domain of an IgG class, preferably an Fv domain of human IgG.

The engineered antibodies of the invention characteristically contain an engineered hinge region, the "first engineered hinge region", in a first monomer, which is comprised of a truncated IgG1 hinge region portion and a truncated IgG4 hinge region portion or is a modified IgG4 hinge region, whereby the hinge structure comprised of the first engineered hinge region coupled to the second hinge region comprises at least two interchain disulfide bonds. The engineered hinge region is composed of natural amino acids, including cysteine residues for forming at least two interchain disulfide bonds between heavy chains.

The wild-type hinge region of IgG1 comprises 15 amino acids (e.g., EPKSCDKTHTCPPCP (SEQ ID NO: 9)) and is very flexible, whereas the hinge of IgG4 is shorter, only 12 amino acids (supra). Wild-type IgG1 and IgG4 differ by one amino acid in the core hinge region (EU numbering 226-229): the IgG hinge with the S228P mutation, which is Cys-Pro-Pro-Cys in IgG1 and Cys-Pro-Ser-Cys in IgG4, can be represented by sequence ESKYGPPCPPCP (SEQ ID NO: 10). The S228P mutation forms a polyproline helix in the IgG4 hinge (PPCPPCP), which, in combination with the shorter IgG4 hinge length, further limits its flexibility compared to the IgG1 hinge. The difference in flexibility between the different hinges is of importance for the bioconjugation of antibodies, as the cysteine residues located in the flexible hinge fragments are considered more reactive than the cysteine residues located in the rigid hinges. Experiments have shown that both the heavy-light chain and heavy-heavy chain inter-disulfide bonds of S228P IgG4 are weakly reactive.

The inventors have surprisingly found that the engineered hinge regions of the invention provide drug load-to-antibody ratio (PAR, equivalent to DAR) improvements during bioconjugation, exploiting the difference in accessibility of the interchain disulfide bonds of the hinge domain to the reducing agent compared to the interchain disulfide bonds of the Fab domain. In particular, as previously described, engineered antibodies with engineered hinge regions have several advantages, such as high homogeneity, more controlled DAR, simplified production, desirable pharmacokinetic and/or pharmacodynamic properties, for ADC production and for the ADC product itself.

In some embodiments, the engineered hinge region comprises a sequence of formula (I):

EPKx₁C x₂ x₃ x₄ x₅ x₆ x₇ x₈ CPPCP(I)

Where x ₁ = default or S, preferably S; x ₂ = default or E or S, preferably default; x ₃ = default or S; x ₄ = default or K or D; x ₅ = Y or K, preferably Y; x ₆ = G or T, preferably G; and/or x ₇x₈ = PP, PT, HP or HT, preferably PP. In some embodiments, the engineered hinge region comprises a sequence represented by formula EPKx ₁C x₂ x₃ x₄ x₅ x₆ PPCPPCP. In some embodiments, the engineered hinge region comprises a sequence shown by the formula EPKSC x ₂ x₃ x₄ x₅ x₆ PPCPPCP.

Preferred examples of engineered hinge regions include:

EPKSCESKYGPPCPPCP(SEQ ID NO:1),

EPKSCSKYGPPCPPCP(SEQ ID NO:2),

EPKSCKYGPPCPPCP(SEQ ID NO:3),

EPKSCYGPPCPPCP(SEQ ID NO:4),

EPKCESKYGPPCPPCP(SEQ ID NO:5),

ESKYGHTCPPCP(SEQ ID NO:6),

ESKYGHPCPPCP(SEQ ID NO:7),

ESKYGPTCPPCP (SEQ ID NO: 8); and

A sequence at least 85%, preferably at least 90% and more preferably at least 95% identical to any of the sequences described above.

In some implementations, the engineered hinge region can also include other hinge sections (e.g., upper hinge region sections) located on either or both sides of the hinge region.

For the engineered antibodies of the invention, the term "hinge domain" refers to the portion of the heavy chain where the two hinge regions are coupled. The first and second hinge regions in the two heavy chains are aligned with each other from the N-terminus as described in PCT/CN2018/106766, for example. According to the invention, the second hinge region in the second monomer may be native or may be an engineered TCR hinge region or an antibody hinge region or a hybrid thereof.

The engineered antibodies of the invention comprise an Fc domain with a knob-to-hole mutation to promote heterodimerization. In some embodiments, the Fc domain is a human Fc domain. Preferably, the Fc domain is an IgG Fc domain, i.e. an Fc domain of the IgG class, more preferably an Fc domain of the IgG1 or IgG4 class. The Fc domain has a KIH mutation to effect heterodimerization via the KIH mechanism.

The "pestle (Knobs-in-Holes)" ("KIH") structure is a mechanism to ensure high heterodimerization. It refers to the fact that amino acid engineering can also be selectively used to create steric effects to favor heterodimer formation over homodimer formation, sometimes referred to as "knob and holes". In some embodiments, the first Fc region, i.e., the Fc region in a first monomer comprising an antibody Fab domain, comprises a mortar mutation, and the second Fc region, i.e., the Fc region in a second monomer comprising a second Fab domain with a TCR constant domain substitution, comprises a mortar mutation. This further enhances heterodimerization, avoiding mismatches between the two monomers, thereby providing the desired WuXiBody ^TM structure.

By way of example of embodiment, an engineered antibody of the invention may comprise a set of four chains as set forth in the following (a), (b) and (c):

(a) A first heavy chain comprising the amino acid sequence SEQ ID NO. 11 or a sequence at least 85% identical thereto,

A first light chain comprising the amino acid sequence SEQ ID NO. 15 or a sequence at least 85% identical thereto, a second heavy chain comprising the amino acid sequence SEQ ID NO. 14 or a sequence at least 85% identical thereto, and

A second light chain comprising the amino acid sequence SEQ ID NO. 16 or a sequence at least 85% identical thereto;

(b) A first heavy chain comprising the amino acid sequence SEQ ID NO. 12 or a sequence at least 85% identical thereto,

A first light chain comprising the amino acid sequence SEQ ID NO. 15 or a sequence at least 85% identical thereto, a second heavy chain comprising the amino acid sequence SEQ ID NO. 14 or a sequence at least 85% identical thereto, and

A second light chain comprising the amino acid sequence SEQ ID NO. 16 or a sequence at least 85% identical thereto;

Or (b)

(C) A first heavy chain comprising the amino acid sequence SEQ ID NO. 13 or having a sequence identical to SEQ ID NO. 13

At least 85% of the sequence being identical,

A first light chain comprising the amino acid sequence SEQ ID NO. 15 or a sequence at least 85% identical thereto, a second heavy chain comprising the amino acid sequence SEQ ID NO. 14 or a sequence at least 85% identical thereto, and

A second light chain comprising the amino acid sequence SEQ ID NO. 16 or a sequence at least 85% identical thereto;

Wherein the first heavy chain and first light chain form the first monomer and the second heavy chain and second light chain form the second monomer.

In another aspect, the invention provides a nucleic acid molecule or combination of nucleic acid molecules encoding an engineered antibody of the invention. In some embodiments, each nucleic acid molecule of the nucleic acid molecule or the combination encodes: 11 and 14 to 16 or a sequence at least 85% identical thereto; one or more of the sequences of SEQ ID NOS 12 and 14 to 16 or a sequence at least 85% identical thereto; or one or more of SEQ ID NOS 13 and 14 to 16 or a sequence at least 85% identical thereto. In some embodiments, the nucleic acid molecule may be one or more vectors, particularly expression vectors. It will be appreciated by those skilled in the art that nucleic acids encoding the heavy and light chains of an antibody may be cloned in separate expression vectors and co-transfected into a host for recombinant production of the antibody, or that the coding sequences for these chains may be inserted into the same expression vector. Expression vectors and hosts known in the art may be used in the present invention. Such as, but not limited to, plasmids, viral vectors, synthetic vectors, bacterial hosts, yeast, insect cells, and animal cells, such as CHO cells. In some embodiments, the nucleic acid molecule (e.g., vector) or combination of nucleic acid molecules may be provided in the form of a kit, which may optionally include instructions for recombinantly producing the antibody using the nucleic acid molecule.

Antibody-drug conjugates

In one aspect of the invention, provided herein are antibody-drug conjugates comprising an engineered antibody of the invention coupled to one or more drug molecules via a linker.

As described above, the engineered antibodies of the invention comprise a first Fab domain which is an antibody Fab domain and a second Fab domain comprising an Fv domain and a TCR constant domain fused thereto. The first Fab domain and the second Fab domain may have the same or different binding specificities, and the antibody Fab domain and Fv domain may each be derived from any antibody, particularly those related to clinical use, such as antibodies that specifically bind to a Tumor Antigen (TA), such as a Tumor Specific Antigen (TSA) and a Tumor Associated Antigen (TAA).

The present invention is not particularly limited as to the available drugs (also referred to as "drug loading"). Medicaments useful in the present invention include cytotoxic drugs, particularly those used in cancer therapy. Such agents include, but are not limited to, DNA damaging agents, DNA binding agents, antimetabolites, enzyme inhibitors (e.g., thymidylate synthase inhibitors and topoisomerase inhibitors), tubulin inhibitors, and toxins (e.g., toxins of bacterial, fungal, plant, or animal origin). Specific examples include, for example, paclitaxel, methotrexate, dichlormethotrexate, 5-fluorouracil, 6-mercaptopurine, cytarabine, melphalan, epoxyvinblastine, vinpocetine, actinomycin, daunorubicin, doxorubicin, mitomycin C, mitomycin A, carminomycin, aminopterin, tarithromycin, podophyllotoxin and podophyllotoxin derivatives such as etoposide or etoposide phosphate, vincristine, vindesine, taxanes including paclitaxel, docetaxel, butyric acid, N8-acetylspermidine, camptothecin, epothilone, alkene-diacetylene, docarubicin A, docarubicin SA, calicheamicin, camptothecin, hamitin, maytansine (including DM1, DM2, DM3, DM 4) and the group of raystatin (including monomethyl aureostatin E (MMAE), monomethyl aureostatin (Ofα), and monomethyl aureostatin (MMAD). In some embodiments, auristatins, such as MMAE, are preferred. The drug may be attached to the linker by any suitable method known in the art. In some embodiments, the drug participates in a coupling reaction in the form of an intermediate linker-drug loading compound, such as "MC-vc-PAB-MMAE".

The drug employed in the present invention may be conjugated to an antibody via a linker. There are various connectors for ADCs in the art. The present invention is not particularly limited as to a useful linker as long as it contains a moiety capable of reacting with a thiol group on an antibody to thereby bind to the antibody. Particularly suitable for use in the present invention are the aminoacyl-imide (amleimido) or haloacyl-functionalized linkers. Examples include, but are not limited to, -MC-vc-PAB- ("MC": maleimide-hexanoyl ";" vc ":" -Val-Cit ";" PAB ": p-aminobenzyl), -MC-GGFG- (" -GGFG ":" -Gly-Gly-Phe-Gly- "tetrapeptide), -MC-vc-, -MC-and-SMCC- (succinimidyl-4- (N-maleimidomethyl) cyclohexane-1-carboxylate). In some embodiments, the linker is-MC-vc-PAB-.

In some embodiments, the linker-drug load is attached to a cysteine residue that is reacted by a reduction reaction to open a selected interchain disulfide bond. In some embodiments, the drug to antibody ratio (DAR) of the conjugates of the invention may be about 2 to 6, preferably about 2 or about 6. The ratio may be an average of the population of molecules, e.g., the average DAR of the ADC population is DAR2 or DAR6. Furthermore, in one of the preferred embodiments, the conjugate has two drug molecules, both linked to the antibody Fab domain, and the TCR constant domain has substantially no drug molecules attached thereto. In another preferred embodiment, the conjugate has 6 drug molecules, all attached to the antibody Fab domain and hinge domain, and the TCR constant domain has substantially no drug molecules attached thereto.

In another aspect, provided herein is a composition comprising or consisting of a mixture of an antibody-drug conjugate of the invention, wherein at least about 65%, preferably at least about 70%, at least about 75%, at least about 80%, or at least about 90% of the DAR in the mixture is 2 (i.e., DAR 2). Preferably, both drug molecules of the DAR2 conjugate are attached to the antibody Fab domain, and the TCR constant domain has substantially no drug molecules attached thereto. Also provided herein is a product comprising or consisting of a mixture of an antibody-drug conjugate of the invention, wherein at least about 80%, preferably at least about 85%, or at least about 90% of the antibody-drug conjugate has a drug/antibody ratio of 6 (i.e., DAR 6). Preferably, all 6 drug molecules of the DAR6 conjugate are linked to the antibody Fab domain and hinge domain, with substantially no drug molecules linked to the TCR constant domain.

In another aspect, the invention also provides a pharmaceutical composition comprising an antibody-drug conjugate as described above or a mixture thereof and a pharmaceutically acceptable carrier.

Preparation of antibody-drug conjugates

The ADC of the present invention may be prepared by any suitable method known in the art. In the present invention, the linker-drug load is coupled at the cysteine residue that is released from the disulfide bond by reduction with a mild reducing agent. Specifically, the engineered hinge regions of the invention alter the reduction reactivity of disulfide bonds in the hinge domain, and thus, partial reduction of antibodies by mild reducing agents allows the disulfide bonds to be selectively reduced. Furthermore, the introduction of a TCR constant domain in one of the Fab domains is more advantageous for controlling DAR in ADC products. In general, the present invention results in a highly homogeneous ADC product with better DAR control using engineered hinge regions and the introduction of TCR constant domains, comprising a conjugate of two molecules of linker-drug load and attached predominantly to an antibody Fab domain, or a conjugate of six molecules of linker-drug load and attached predominantly to an antibody Fab domain and hinge domain, to which the TCR constant domains are attached substantially without linker-drug load.

Provided herein are methods of making the antibody-drug conjugates of the invention. Briefly, the method may comprise a partial reduction reaction of the antibody and a coupling reaction of the partially reduced antibody to a linker-drug load, as schematically illustrated in fig. 1. Preferably, the coupling is performed in a reducing buffer containing an organic solvent as an additive for facilitating dissolution of the linker-drug load. In particular, the method may comprise coupling the partially reduced antibody of the invention with a linker-drug-loaded compound bearing a maleimide or haloacetyl group via a Michael addition reaction. Partially reduced antibodies the engineered antibodies of the invention may be partially reduced using mild reducing agents. In some embodiments, the method may include:

partial reduction of the engineered antibodies of the invention with mild reducing agents, and

The partially reduced antibodies are coupled to a linker-drug-loaded compound bearing a maleimide or haloacetyl group via a Michael addition reaction.

In some embodiments, the mild reducing agent is TCEP or DTT. In some embodiments, the reducing agent/antibody ratio is about 1 to 20, preferably about 2 to 15, and more preferably about 3 to 10. In some embodiments, the partial reduction is performed at a pH of about 4.0 to 8.0, preferably about 5 to 7. In some embodiments, the partial reduction is performed for about 0.5 to 24 hours, preferably about 1 to 24 hours, about 1 to 16 hours, about 10 to 24 hours, or about 16 to 24 hours. In some embodiments, the partial reduction is performed at a temperature of about 4 to 37 ℃, preferably about 4 to 15 ℃ or about 4 to 10 ℃. In some embodiments, the present methods provide a product comprising or consisting of a mixture of an antibody-drug conjugate of the invention, wherein at least about 65%, preferably at least about 70%, at least about 75%, at least about 80%, or at least about 90% of the DAR in the mixture is 2. Preferably, both drug molecules of the DAR2 conjugate are attached to the antibody Fab domain, and the TCR constant domain has substantially no drug molecules attached thereto.

In some other embodiments, the mild reducing agent is TCEP or DTT. In some embodiments, the reducing agent/antibody ratio is about 1 to 20, preferably about 3 to 20, about 3 to 10, or about 10 to 20. In some embodiments, the partial reduction is performed at a pH of about 4.0 to 8.0, preferably about 6 to 8. In some embodiments, the partial reduction is performed for about 0.5 to 24 hours, preferably about 3 to 24 hours, about 3 to 16 hours, about 10 to 24 hours, or about 16 to 24 hours. In some embodiments, the partial reduction is performed at a temperature of 4 to 37 ℃, preferably about 4 to 15 ℃ or about 4 to 10 ℃. In some embodiments, the present methods provide a product comprising or consisting of an antibody-drug conjugate mixture of the invention having a drug/antibody ratio of 6 (i.e., DAR 6) of at least about 80%, preferably at least about 85%, or at least about 90%. Preferably, all 6 drug molecules of the DAR6 conjugate are linked to the antibody Fab domain and hinge domain, with substantially no drug molecules linked to the TCR constant domain.

In some embodiments, the coupling is performed in a buffer having a pH of about 4.0 to 8.0, optionally with an organic additive (e.g., an organic solvent or organic co-solvent) in an amount of about 0.0 wt.% to 20.0 wt.%, preferably about 5.0 wt.% to 15.0 wt.%, or about 10.0 wt.% to 15.0 wt.%. In some embodiments, the drug/antibody ratio may be about 7-20, preferably about 7-10; the reaction temperature may be about 4 to 37 ℃, preferably about 4 to 20 ℃ or about 4 to 10 ℃; and/or the reaction time may be about 0.5 to 4 hours, preferably about 1 to 3 hours.

Treatment of

The antibody drug conjugates of the application are useful for treating a disease, disorder or condition in a subject in need thereof, the treatment comprising administering to the subject a therapeutically effective amount of the antibody drug conjugate. The application also provides an antibody drug conjugate of the application for use in treating a disease, disorder or condition in a subject in need thereof. Diseases treated include, but are not limited to, cancers, including solid tumors and hematological cancers. Examples of such cancers include, but are not limited to, breast cancer, gastric cancer, pancreatic cancer, liver cancer, lung cancer (e.g., NSCLC), head and neck cancer, colorectal cancer, B-cell lymphoma (e.g., non-hodgkin's lymphoma (NHL)), and leukemia.

Abbreviations (abbreviations)

ADC: antibody-drug conjugates

CH: heavy chain constant region

CMC: chemical composition production and control

DAR: drug/antibody ratio

DMA: n, N' -dimethylacetamide

DTT:1, 4-dithiothreitol

EGFR: epidermal growth factor receptor

Fab: antigen binding fragments

Fc: the fragment may be crystallized in the presence of a solvent,

FDA: food and drug administration

FGE: formylglycine generating enzyme

HIC: hydrophobic interaction chromatography

HPLC: high performance liquid chromatography

IC50: half maximal inhibitory concentration

IgG: immunoglobulin G

MC: maleimide-hexanoyl group

MED: minimum effective dose

MMAE: monomethyl auristatin E

MTD: maximum tolerated dose

MWCO: molecular weight cut-off

NaCl: sodium chloride

NNAA: unnatural amino acids

MTG: microbial transglutaminase

PAB: para aminobenzyl group

PAR: drug load-to-antibody ratio

RP: reverse phase

SEC: size exclusion chromatography

TCEP: tris (2-carboxyethyl) phosphine

VH: heavy chain variable region

Eq: reducing agent/antibody molar ratio

Examples

General method

Preparation of antibodies

All antibody molecules herein were subjected to ash hamster (Cricetulus griseus) codon optimisation, synthesized according to standard molecular biology methods and cloned into production vectors, and then mass-amplified from TOP10 E.coli followed by plasmid extraction.

72 Hours prior to transfection, CHO K1 host cells were seeded at 2-4E5 cells/mL in CD CHO medium. CELL density was calculated with Vi-CELL-dotted host CELLs, and 290g was centrifuged for 7 min and resuspended in fresh CD CHO medium pre-warmed prior to transfection. Before use, the resuspended host cells were incubated in a Kuhner shaker (36.5 ℃,75% humidity, 6% CO ₂, 120 rpm) for use.

A total of 4mg of plasmid encoding the antibody of interest was added to the host cell suspension followed by 12mg of polyetherimide. The transfected cultures were incubated in a Kuhner shaker at 36.5℃with 75% humidity, 6% CO ₂, 120rpm for 4 hours. The self-contained feed medium was added and the transfected cultures were incubated in a Kuhner shaker at 31℃with 75% humidity, 6% CO ₂, 120rpm for 9-10 days.

On the harvest day, the transfected cultures were clarified by centrifugation at 1,000g for 10min followed by centrifugation at 10,000g for 40min, and then filtered off with a 0.22 μm filter. The supernatant was taken for titer and purified by ProA chromatography. ProA eluate was neutralized by adding 1-2% neutralization buffer (1M Tris-HCl, pH 9.0) and then formulated in 20mM histidine-acetate buffer pH 5.5.

All proteins were subjected to quality control detection prior to conjugation, including reduced and non-reduced SDS-PAGE, SEC-HPLC, endotoxin detection by LAL gel method (LAL gel clot assay), and molecular characterization by mass spectrometry.

Preparation of ADC

To a 1mg/ml to 20mg/ml antibody solution in a buffer (pH 4.0-8.0, preferably in the preparation of DAR6, and more preferably in the pH 6.0-8.0, e.g., histidine-acetate buffer) is added 1 to 20eq (preferably 2-15eq for DAR2, preferably 3-20eq for DAR 6) reducing agent (e.g., TCEP or DTT). The reduction is carried out at 4-37℃and the reaction is gently shaken or stirred for 0.5 to 24 hours (preferably 1-24 hours for DAR2 and preferably 3-24 hours for DAR 6). Without purification, an organic co-solvent (e.g., DMA) was added to the partially reduced antibody to a concentration of 0% to 20%, maleimide or haloacetyl functionalized linker-drug loading of 7-20eq. The coupling reaction was carried out at 4-37 ℃ with gentle shaking or stirring for 0.5 to 4 hours (fig. 1). Final coupled product characterization included UV-vis concentration, HIC-HPLC conjugate distribution and DAR, LC-MS drug loading on light and heavy chains, RP-HPLC free drug residue, SEC-HPLC aggregate and purity, kinetic turbidimetry endotoxin levels.

HIC-HPLC

SEC-HPLC

RP-HPLC for measuring drug load

The process comprises the following steps: mu.l of the ADC sample was mixed with 75. Mu.l of 8M guanidine hydrochloride and 5. Mu.l of Tris-HCl, pH 8.0. To the mixture was added 1. Mu.l of a 0.5M TCEP solution. The reaction was carried out at 37℃for 30 minutes (min) and then the drug loading on the antibody was determined by RP-HPLC.

Determination of free drug by RP-HLPC

The process comprises the following steps: 85 μl of ADC solution was mixed with 15 μl of DMA, and then the protein was precipitated with 100 μl of precipitation buffer (NaCl saturated 37.5% v/v methanol/acetonitrile solution), and vortexed at 1400rpm for 10min at 22 ℃.

The samples were centrifuged at 16000rpf for 10 minutes. The supernatant was taken and tested by RP-HPLC with a standard sample to determine the free drug.

LC-MS determination of DAR

The process comprises the following steps: 85 μl of ADC solution was mixed with 15 μl of 50mM TCEP and then incubated at 22deg.C for 30 minutes.

The samples were tested for DAR using LC-MS.

The following examples are presented for the purpose of illustration only and are not intended to limit the scope of the invention.

Example 1

An engineered hinge region of sequence EPKSCSKYGPPCPPCP (SEQ ID NO: 2) was used to construct anti-Her 2 antibodies 886-39 (IgG-TCR, igG1-Fab, igG 4-Fc), also referred to as "WBP886-39" in FIG. 14. The first Light Chain (LC) sequence is SEQ ID NO. 15, the first Heavy Chain (HC) sequence is SEQ ID NO. 11, the second LC sequence is SEQ ID NO. 16, and the second HC sequence is SEQ ID NO. 14. The first LC forms with the first HC a monomer having an antibody Fab and Fc region containing a "mortar" mutation, and the second LC forms with the second HC a monomer having a Fab domain containing a TCR constant domain substitution and an Fc region containing a "mortar" mutation. The antibodies are recombinantly produced as described in the general methods section.

The antibody was dissolved in 20mM histidine buffer (150 mM NaCl, pH 5.5) at a concentration of 8.66mg/ml. The preparation buffer was changed to PBS pH7.0 and the concentration was 4mg/ml. To the antibody solution 2.0eq of TCEP was added and the mixture incubated at 4 ℃ for 16 hours. DMA was added to the reduced antibody to a concentration of 10% followed by 7eq of MC-vc-PAB-MMAE. The coupling reaction was carried out at 4℃for 1 hour. The coupled product was purified with a 40KD MWCO desalting column and stored in PBS pH 7.0. DAR and drug distribution were determined by HIC-HPLC and the coupling position was determined by LC-MS, thereby performing characterization of the final product (FIGS. 2 and 3). HIC-HPLC results for DAR and drug distribution are shown below:

The results show that the introduction of TCR constant domains and engineering of hinge domains in antibodies, the improved homogeneity of ADCs made using the antibodies was unexpected, as DAR2 was the major product. The product is highly homogeneous, and the percentage of the main product DAR2 type ADC reaches 90.5%. Furthermore, LC-MS results show that drug molecules are predominantly loaded in the antibody Fab domain, with no drug loading in the TCR constant domain.

Example 2

An engineered hinge region of sequence EPKSCKYGPPCPPCP (SEQ ID NO: 3) was used to construct anti-Her 2 antibodies 886-40 (IgG-TCR, igG1-Fab, igG 4-Fc), also referred to as "WBP886-40" in FIG. 14. The first Light Chain (LC) sequence is SEQ ID NO. 15, the first Heavy Chain (HC) sequence is SEQ ID NO. 12, the second LC sequence is SEQ ID NO. 16, and the second HC sequence is SEQ ID NO. 14. The first LC forms with the first HC a monomer having an antibody Fab and Fc region containing a "mortar" mutation, and the second LC forms with the second HC a monomer having a Fab domain containing a TCR constant domain substitution and an Fc region containing a "mortar" mutation. The antibodies are recombinantly produced as described in the general methods section.

The antibody was dissolved in 20mM histidine (150 mM NaCl, pH 5.5) at a concentration of 10.83mg/ml. The preparation buffer was changed to PBS pH7.0 and the concentration was 4mg/ml. To the antibody solution 2.0eq of TCEP was added and the mixture incubated at 4 ℃ for 16 hours. DMA was added to the reduced antibody to a concentration of 10% followed by 7eq of MC-vc-PAB-MMAE. The coupling reaction was carried out at 4℃for 1 hour. The coupled product was purified with a 40KD MWCO desalting column and stored in PBS pH 7.0. DAR and drug distribution were determined by HIC-HPLC and the coupling position was determined by LC-MS, thereby performing characterization of the final product (FIGS. 6 and 7). HIC-HPLC results for DAR and drug distribution are shown below:

The results show that the introduction of TCR constant domains and engineering of hinge domains in antibodies, the improved homogeneity of ADCs made using the antibodies was unexpected, as DAR2 was the major product. The product is highly homogeneous, and the percentage of the main product DAR2 type ADC reaches 73.2 percent. Furthermore, LC-MS results show that drug molecules are predominantly loaded in the antibody Fab domain, with no drug loading in the TCR constant domain.

Example 3

An engineered hinge region of sequence EPKSCYGPPCPPCP (SEQ ID NO: 4) was used to construct anti-Her 2 antibodies 886-41 (IgG-TCR, igG1-Fab, igG 4-Fc), also referred to as "WBP886-41" in FIG. 14. The first Light Chain (LC) sequence is SEQ ID NO. 15, the first Heavy Chain (HC) sequence is SEQ ID NO. 13, the second LC sequence is SEQ ID NO. 16, and the second HC sequence is SEQ ID NO. 14. The first LC forms with the first HC a monomer having an antibody Fab and Fc region containing a "mortar" mutation, and the second LC forms with the second HC a monomer having a Fab domain containing a TCR constant domain substitution and an Fc region containing a "mortar" mutation. The antibodies were recombinantly produced as described in the general methods section.

The antibody was dissolved in 20mM histidine (150 mM NaCl, pH 5.5) at a concentration of 4mg/ml. To the antibody solution was added 14.0eq of TCEP and the mixture was incubated for 16 hours at 4 ℃. DMA was added to the reduced antibody to a concentration of 10% followed by 7eq of MC-vc-PAB-MMAE. The coupling reaction was carried out at 4℃for 1 hour. The coupled product was purified using a 40KD MWCO desalting column and stored in 20mM histidine buffer, pH 5.5. DAR and drug distribution were determined by HIC-HPLC and the coupling position was determined by LC-MS, thereby performing characterization of the final product (FIGS. 10 and 11). HIC-HPLC results for DAR and drug distribution are shown below:

The results show that the introduction of TCR constant domains and engineering of hinge domains in antibodies, the improved homogeneity of ADCs made using the antibodies was unexpected, as DAR2 was the major product. The product is highly homogeneous, and the percentage of the main product DAR2 type ADC reaches 68.2 percent. Furthermore, LC-MS results show that drug molecules are predominantly loaded in the antibody Fab domain, with no drug loading in the TCR constant domain.

Example 4

Anti-Her 2 antibody 886-39 was dissolved in 20mM histidine (150 mM NaCl, pH 5.5) at a concentration of 8.66mg/ml. The preparation buffer was changed to PBS pH8.0 and the concentration was 4mg/ml. To the antibody solution 12eq of TCEP was added and the mixture incubated at 4 ℃ for 16 hours. DMA was added to the reduced antibody to a concentration of 10% followed by 13eq of MC-vc-PAB-MMAE. The coupling reaction was carried out at 4℃for 1 hour. The coupled product was purified using a 40KD MWCO desalting column and stored in 20mM histidine-acetate buffer, pH 5.5. DAR and drug distribution were determined by HIC-HPLC and the coupling position was determined by LC-MS, thereby performing characterization of the final product (FIGS. 4 and 5). HIC-HPLC results for DAR and drug distribution are shown below:

The results show that the introduction of TCR constant domains and engineering of hinge domains in antibodies, the improved homogeneity of ADCs made using the antibodies was unexpected, as DAR6 was the major product. The product is highly homogeneous, and the percentage of the main product DAR6 type ADC reaches 87.1 percent. Furthermore, LC-MS results showed that the TCR constant domain was not drug loaded.

Example 5

Anti-Her 2 antibody 886-40 was dissolved in 20mM histidine (150 mM NaCl, pH 5.5) at a concentration of 10.83mg/ml. The preparation buffer was changed to PBS pH8.0 and the concentration was 4mg/ml. To the antibody solution was added 14.0eq of TCEP and the mixture was incubated for 16 hours at 4 ℃. DMA was added to the reduced antibody to a concentration of 10% followed by 17eq of MC-vc-PAB-MMAE. The coupling reaction was carried out at 4℃for 1 hour. The coupled product was purified using a 40KD MWCO desalting column and stored in 20mM histidine-acetate buffer, pH 5.5. DAR and drug distribution were determined by HIC-HPLC, whereby final product characterization was performed (FIGS. 8 and 9). HIC-HPLC results for DAR and drug distribution are shown below:

The results show that the introduction of TCR constant domains and engineering of hinge domains in antibodies, the improved homogeneity of ADCs made using the antibodies was unexpected, as DAR6 was the major product. The product is highly homogeneous, and the mass percentage of the main product DAR6 reaches 84.4%. Furthermore, LC-MS results showed that the TCR constant domain was not drug loaded.

Example 6

Anti-Her 2 antibody 886-41 was dissolved in 20mM histidine (150 mM NaCl, pH 5.5) at a concentration of 10.40mg/ml. The preparation buffer was changed to PBS pH8.0 and the concentration was 4mg/ml. To the antibody solution was added 16.0eq of TCEP and the mixture was incubated for 16 hours at 4 ℃. DMA was added to the reduced antibody to a concentration of 10% followed by 19eq of MC-vc-PAB-MMAE. The coupling reaction was carried out at 4℃for 1 hour. The coupled product was purified using a 40KD MWCO desalting column and stored in 20mM histidine-acetate buffer, pH 5.5. Final product characterization was performed using HIC-HPLC to determine DAR and drug distribution (fig. 12 and 13). HIC-HPLC results for DAR and drug distribution are shown below:

The results show that the introduction of TCR constant domains and engineering of hinge domains in antibodies, the improved homogeneity of ADCs made using the antibodies was unexpected, as DAR6 was the major product. The product is highly homogeneous, and the percentage of the main product DAR6 type ADC reaches 87.5 percent. Furthermore, LC-MS results showed that the TCR constant domain was not drug loaded.

Claims (17)

1. An engineered dimeric antibody, wherein a first monomer comprises a first Fab domain and a first engineered hinge region operably linked thereto and a first Fc region operably linked thereto thereafter, and a second monomer comprises a second Fab domain and a second hinge region operably linked thereto and a second Fc region operably linked thereto thereafter;

wherein the first Fab domain is an antibody Fab domain and the second Fab domain comprises an antibody Fv domain and a TCR constant domain fused thereto; and

Wherein the first engineered hinge region consists of a truncated IgG1 hinge region portion and a truncated IgG4 hinge region portion or is a modified IgG4 hinge region, the hinge domain formed by coupling the first engineered hinge region to the second hinge region comprises at least two interchain disulfide bonds, and the engineered hinge region comprises the sequence of SEQ ID NO. 3; and

Wherein the Fc domain formed by coupling the first Fc region to the second Fc region comprises a knob-to-socket mutation.

2. The engineered antibody of claim 1, wherein the second monomer is WuXiBody ^TM antibody half-antibody comprising a TCR constant domain.

3. The engineered antibody of claim 1, wherein the antibody Fab domain is of the human IgG1 type; and/or the Fv domain is of the human IgG class.

4. The engineered antibody of claim 1, wherein the Fc domain is of the human IgG1 or human IgG4 type.

5. The engineered antibody of claim 1, wherein the first Fc region comprises a mortar mutation and the second Fc region comprises a pestle mutation.

6. The engineered antibody of claim 1, comprising,

A first heavy chain comprising the amino acid sequence SEQ ID NO:12,

A first light chain comprising the amino acid sequence SEQ ID NO. 15,

A second heavy chain comprising the amino acid sequence SEQ ID NO. 14, and

A second light chain comprising the amino acid sequence SEQ ID NO. 16;

Wherein the first heavy chain and first light chain form the first monomer and the second heavy chain and second light chain form the second monomer.

7. An antibody-drug conjugate comprising the engineered antibody of claim 1 conjugated to one or more drug molecules via a linker.

8. The antibody-drug conjugate of claim 7, characterized by one or more of the following:

wherein the linker is-MC-vc-PAB-;

wherein the drug is MMAE;

Wherein the drug/antibody ratio of the conjugate is 2 or 6;

Wherein said conjugate has two drug molecules both linked to said antibody Fab domain of said engineered antibody, said TCR constant domain having substantially no drug molecules linked thereto; and/or

Wherein said conjugate has six drug molecules, all attached at said antibody Fab domain and said hinge domain of said engineered antibody, said TCR constant domain having substantially no drug molecules attached thereto.

9. A composition comprising or consisting of the mixture of antibody-drug conjugates of claim 7, wherein the drug/antibody ratio of at least 65% of the antibody-drug conjugates is 2; or wherein at least 80% of the antibody-drug conjugate has a drug/antibody ratio of 6.

10. A pharmaceutical composition comprising the antibody-drug conjugate of claim 7 and a pharmaceutically acceptable carrier.

11. A method of making the antibody-drug conjugate of claim 7 comprising coupling the partially reduced antibody of claim 1 to a linker-drug cargo compound bearing a maleimide or haloacetyl moiety via a michael addition reaction.

12. The method of claim 11, further comprising partially reducing the engineered antibody of claim 1 with a mild reducing agent to provide the partially reduced antibody.

13. The method of claim 12, having one or more of the following features:

the mild reducing agent is TCEP or DTT;

The reducer/antibody ratio is 1-20;

the partial reduction step is carried out at a pH of 4.0 to 8.0;

The partial reduction step is carried out for 0.5 to 24 hours; and/or

The partial reduction step is carried out at a temperature of 4 to 37 ℃.

14. The method of claim 13, having one or more of the following features:

the reducer/antibody ratio is 2-15; and/or

The partial reduction step is carried out for 1 to 24 hours.

15. The method of claim 13, having one or more of the following features:

the reducer/antibody ratio is 3-20;

The partial reduction step is carried out at a pH of 6 to 8; and/or

The partial reduction step is carried out for 3 to 24 hours.

16. An antibody-drug conjugate product obtainable by the method of claim 13 comprising or consisting of a mixture of antibody-drug conjugates of claim 7, wherein the drug/antibody ratio of at least 65% of the antibody-drug conjugates is 2; or the antibody-drug conjugate product comprises or consists of a mixture of the antibody-drug conjugates of claim 7, wherein the drug/antibody ratio of at least 80% of the antibody-drug conjugates is 6.

17. Use of the antibody-drug conjugate of claim 7 for the manufacture of a medicament for the treatment of cancer, such as breast cancer.