治疗性抗体的研究进展

作为一种具有靶向性的生物大分子,单克隆抗体始终是人们关注的热点之一,被广泛用于治疗肿瘤、病毒感染和抗移植排斥等。但鼠源单克隆抗体的临床应用受限于诱导产生人抗鼠抗体、肿瘤渗入量低、亲和力低和半衰期短等。随着分子生物学技术的发展及其向各学科的渗透,通过基因操作技术对抗体进行改造,可使其适用于多种疾病的治疗。抗体人源化已经成为治疗性抗体的发展趋势,同时各种抗体衍生物也不断涌现,它们从不同角度克服了抗体本身的应用局限,也为治疗人类疾病提供了利器。本文简要介绍上述技术的基本原理、特点和治疗性抗体的研究进展。     

抗体基因工程

抗体基因工程阎锡蕴,田华松,田波（中国科学院微生物研究所,北京１０００８０）自从１９７５年杂交瘤技术问世以来,单克隆抗体在临床诊断和基础研究中的应用越来越广泛。但在疾病治疗方面还没有达到令人满意的效果。其主要原因是目前所获得的单克隆抗体绝大多数都来源...     

重组抗体药物研究进展及应用

重组抗体药物的发展经历了鼠源单克隆抗体（McAb）、人 鼠嵌合抗体、人源化抗体和全人抗体等阶段,目前初步应用于抗肿瘤、抗自身免疫病、抗感染等领域。保持和提高抗体的亲和力、降低抗体的免疫原性是抗体药物基因工程改造的两大原则。在嵌合抗体成功的基础上,通过CDR移植、表面修饰、抗体库以及转基因鼠技术,逐步提高人源化程度至100%。然而,实验室水平的研究结果与实际应用仍然存在一定差距。就重组抗体药物的基本概况、现存的问题与可能的解决办法以及在肿瘤、病毒性疾病和阿尔茨海默病治疗上的应用情况等进行了综述。     

基因工程抗体研究进展

基因工程抗体研究进展刘喜富,黄华梁（中国科学院遗传研究所北京１００１０１）自１９７５年Ｋｏｈｌｅｒ和Ｍｉｌｓｔｅｉｎ等创立了杂交瘤技术以来,单克隆抗体已广泛应用于临床疾病的诊断,治疗和预防以及基础理论研究等多个领域,取得了令人鼓舞的结果。但由于鼠单克隆抗体对人体具有免疫原性,不能重复使用,影响疗效,而且生产单抗的成本较高,难以普及使用,围绕如何降低鼠源单克隆抗体的免疫原性以及在大肠杆菌中表达抗体基因的问题, 基因工程抗体技术得以产生和发展。     

基因工程抗体中噬菌体抗体库技术的应用

通过基因工程可以大规模地制备能与人相容的单克隆抗体或片段。其中,噬菌体抗体抗库技术可以模拟体内抗体产生和成熟过程,不经细胞杂交,甚至不经免疫制备针对任何抗原的单克隆抗体。就基因工程抗体及噬菌抗体库技术的发展与应用作一概述 。     

抗体库的发展及未来

抗体库的出现为制备人源性单抗开辟了一条行之有效的途径．虽然该技术问世只有短短几年的时间,但其筛选系统已有了很大的改进;现已能够快速地从抗体库中筛选出各种具有不同用途的抗体．从而克服了传统杂交瘤技术的某些局限性．文章就抗体库的发展及其应用前景进行了概述.     

单克隆抗体研究进展

自Khler和Mistein创建杂交瘤技术以来,目前随着分子生物学技术的渗透,出现了各种特异的单克隆抗体,并得到广泛应用。本文着重介绍了人源单抗、基因工程单抗、双特异性单抗的基本原理,同时综述了杂交瘤技术的各个环节在近年来取得的一些进展,为研制高质量的单抗提供了更为简便而灵敏的手段。     

基因工程抗体：单克隆抗体技术发展的新时代

基因工程抗体：单克隆抗体技术发展的新时代俞晓峰,黄策（军事医学科学院微生物与流行病研究所,北京１０００７１）关键词基因工程抗体,单克隆抗体Ｋｏｈｌｅｒ和Ｍｉｌｓｔｅｉｎ于１９７５年创立的用杂交瘤技术制备单克隆抗体（ＭＡｂ）的新方法标志着细胞工程抗体时...     

基因工程抗体中噬茵体抗体库技术的应用

通过基因工程可以大规模地制备能与人相容的单克隆抗体或片段.其中,噬茵体抗体库技术可以模拟体内抗体产生和成熟过程,不经细胞杂交,甚至不经免疫制备针对任何抗原的单克隆抗体.就基因工程抗体及噬茵体抗体库技术的发展与应用作一概述.     

基因工程抗体研究进展

临床治疗中人抗鼠抗体反应的出现使鼠源性单克隆抗体的应用受到了极大的限制。为降低其免疫原性,人们利用基因工程技术对鼠源抗体进行改造,以减少其鼠源成分。简要概述了目前研究比较多的几种基因工程抗体及其临床应用。     

Calcium-dependent antigen binding as a novel modality for antibody recycling by endosomal antigen dissociation

The pH-dependent antigen binding antibody, termed a recycling antibody, has recently been reported as an attractive type of second-generation engineered therapeutic antibody. A recycling antibody can dissociate antigen in the acidic endosome, and thus bind to its antigen multiple times. As a consequence, a recycling antibody can neutralize large amounts of antigen in plasma. Because this approach relies on histidine residues to achieve pH-dependent antigen binding, which could limit the epitopes that can be targeted and affect the rate of antigen dissociation in the endosome, we explored an alternative approach for generating recycling antibodies. Since calcium ion concentration is known to be lower in endosome than in plasma, we hypothesized that an antibody with antigen-binding properties that are calcium-dependent could be used as recycling antibody. Here, we report a novel anti-interleukin-6 receptor (IL-6R) antibody, identified from a phage library that binds to IL-6R only in the presence of a calcium ion. Thermal dynamics and a crystal structure study revealed that the calcium ion binds to the heavy chain CDR3 region (HCDR3), which changes and possibly stabilizes the structure of HCDR3 to make it bind to antigen calcium dependently (PDB 5AZE). In vitro and in vivo studies confirmed that this calcium-dependent antigen-binding antibody can dissociate its antigen in the endosome and accelerate antigen clearance from plasma, making it a novel approach for generating recycling antibody.     

Rabbit immune repertoires as sources for therapeutic monoclonal antibodies: the impact of kappa allotype-correlated variation in cysteine content on antibody libraries selected by phage display

The rabbit immune repertoire has long been a rich source of diagnostic polyclonal antibodies. Now it also holds great promise as a source of therapeutic monoclonal antibodies. On the basis of phage display technology, we recently reported the first humanization of a rabbit monoclonal antibody. The allotypic diversity of rabbit immunoglobulins prompted us to compare different rabbit immune repertoires for the generation and humanization of monoclonal antibodies that bind with strong affinity to antigens involved in tumor angiogenesis. In particular, we evaluated the diversity of unselected and selected chimeric rabbit/human Fab libraries that were derived from different kappa light chain allotypes. Most rabbit light chains have an extra disulfide bridge that links the variable and constant domains in addition to the two intrachain disulfide bridges shared with mouse and human kappa light chains. Here we evaluate the impact of this increased disulfide bridge complexity on the generation and selection of chimeric rabbit/human Fab libraries. We demonstrate that rabbits with mutant bas and wild-type parental b9 allotypes are excellent sources for therapeutic monoclonal antibodies. Featured among the selected clones with b9 allotype is a rabbit/human Fab that binds with a dissociation constant of 1nM to both human and mouse Tie-2, which will facilitate its evaluation in mouse models of human cancer. Examination of 228 new rabbit antibody sequences allowed for a comprehensive comparison of the LCDR3 and HCDR3 length diversity in rabbits. This study revealed that rabbits exhibit an HCDR3 length distribution more closely related to human antibodies than mouse antibodies.     

Transferrin recycling perfusion culture of hybridoma cells

A perfusion culture of hybridoma cells in serum-free medium recycling transferrin was carried out, which greatly reduced the level of transferrin that was needed. The culture was maintained even without supplying transferrin for nine days. IgG concentration reached 1.1 mg ml⁻¹ in a month of recycling and its ratio to the total protein was 45.8%. The affinity of the antibody did not decrease and no degradation was observed after long recycling period. The cell density under recycling condition was 2≈3 times higher than that without recycling. It was indicated that there was autocrine growth promoting activity in the culture supernatant.     

A monoclonal antibody reactive with an activated ras protein expressing valine at position 12

Activated ras transforming genes have been described in a variety of neoplasms and encode 21,000-Dalton (p21) proteins with amino acid substitutions at positions 12, 13, and 61. In this report we describe a monoclonal antibody designated DWP that reacts specifically with synthetic dodecapeptides containing valine at position 12, to a lesser extent with peptides containing cysteine at position 12 and not with peptides containing glycine, arginine, serine, aspartic acid, glutamic acid or alanine at the same position. Western blot and immunoperoxidase studies showed that DWP specifically reacts with activated rasH or rasK proteins in NIH cells transformed by DNA from the human carcinoma cells that encode valine at position 12. DWP did not react with normal p21s encoding glycine at position 12, nor with activated p21s encoding aspartic acid, glutamic acid, arginine, serine, or cysteine at position 12. A survey of human tumor cell lines demonstrated that DWP reacted with the human bladder carcinoma cell line T24 but not with human tumor cell lines previously shown to contain other activating mutations at positions 12 or 61. DWP and perhaps additional antibodies that specifically react with alterations at positions 12 or 61 of the ras protein may be valuable in determining the presence and frequency of activated ras proteins in human malignancy.     

Design and characterization of novel dual Fc antibody with enhanced avidity for Fc receptors

Monoclonal antibodies (mAbs) have become an important class of therapeutics, particularly in the realm of anticancer immunotherapy. While the two antigen-binding fragments (Fabs) of an mAb allow for high-avidity binding to molecular targets, the crystallizable fragment (Fc) engages immune effector elements. mAbs of the IgG class are used for the treatment of autoimmune diseases and can elicit antitumor immune functions not only by several mechanisms including direct antigen engagement via their Fab arms but also by Fab binding to tumors combined with Fc engagement of complement component C1q and Fcγ receptors. Additionally, IgG binding to the neonatal Fc receptor (FcRn) allows for endosomal recycling and prolonged serum half-life. To augment the effector functions or half-life of an IgG1 mAb, we constructed a novel “2Fc” mAb containing two Fc domains in addition to the normal two Fab domains. Structural and functional characterization of this 2Fc mAb demonstrated that it exists in a tetrahedral-like geometry and retains binding capacity via the Fab domains. Furthermore, duplication of the Fc region significantly enhanced avidity for Fc receptors FcγRI, FcγRIIIa, and FcRn, which manifested as a decrease in complex dissociation rate that was more pronounced at higher densities of receptor. At intermediate receptor density, the dissociation rate for Fc receptors was decreased 6- to 130-fold, resulting in apparent affinity increases of 7- to 42-fold. Stoichiometric analysis confirmed that each 2Fc mAb may simultaneously bind two molecules of FcγRI or four molecules of FcRn, which is double the stoichiometry of a wild-type mAb. In summary, duplication of the IgG Fc region allows for increased avidity to Fc receptors that could translate into clinically relevant enhancement of effector functions or pharmacokinetics.     

Therapeutic antibody engineering

It is an important event in any knowledge area when an authority in the field decides that it is time to share all accumulated knowledge and learnings by writing a text book. This does not occur often in the biopharmaceutical industry, likely due to both the highly dynamic environment with tight timelines and policies and procedures at many pharmaceutical companies that hamper knowledge sharing. To take on a task like this successfully, a strong drive combined with a desire and talent to teach, but also an accommodating and stimulating environment is required. Luckily for those interested in therapeutic monoclonal antibodies, Dr. William R. Strohl decided about two years ago that the time was right to write a book about the past, present and future of these fascinating molecules. Dr. Strohl’s great expertise and passion for biotechnology is evident from his life story and his strong academic and industry track record. Dr. Strohl pioneered natural product biotechnology, first in academia as a full professor of microbiology and biochemistry at Ohio State University in Columbus, Ohio and later in industry while at Merck. Despite his notable advances in recombinant natural products, industry interest in this area waned and in 2001 Dr. Strohl sought new opportunities by entering the field of antibody therapeutics. He initiated antibody discovery through phage display at Merck, and then moved to Centocor Research and Development Inc. (now Janssen Biotech, Inc.) in 2008 to head Biologics Research, where he now directs the discovery of innovative therapeutic antibody candidates.     

Non-viral adeno-associated virus-based platform for stable expression of antibody combination therapeutics: Non-viral adeno-associated virus-based platform for stable expression of antibody combination therapeutics

Antibody combination therapeutics (ACTs) are polyvalent biopharmaceuticals that are uniquely suited for the control of complex diseases, including antibiotic resistant infectious diseases, autoimmune disorders and cancers. However, ACTs also represent a distinct manufacturing challenge because the independent manufacture and subsequent mixing of monoclonal antibodies quickly becomes cost prohibitive as more complex mixtures are envisioned. We have developed a virus-free recombinant protein expression platform based on adeno-associated viral (AAV) elements that is capable of rapid and consistent production of complex antibody mixtures in a single batch format. Using both multiplexed immunoassays and cation exchange (CIEX) chromatography, cell culture supernatants generated using our system were assessed for stability of expression and ratios of the component antibodies over time. Cultures expressing combinations of three to ten antibodies maintained consistent expression levels and stable ratios of component antibodies for at least 60 days. Cultures showed remarkable reproducibility following cell banking, and AAV-based cultures showed higher stability and productivity than non-AAV based cultures. Therefore, this non-viral AAV-based expression platform represents a predictable, reproducible, quick and cost effective method to manufacture or quickly produce for preclinical testing recombinant antibody combination therapies and other recombinant protein mixtures.     

Non-viral adeno-associated virus-based platform for stable expression of antibody combination therapeutics

Antibody combination therapeutics (ACTs) are polyvalent biopharmaceuticals that are uniquely suited for the control of complex diseases, including antibiotic resistant infectious diseases, autoimmune disorders and cancers. However, ACTs also represent a distinct manufacturing challenge because the independent manufacture and subsequent mixing of monoclonal antibodies quickly becomes cost prohibitive as more complex mixtures are envisioned. We have developed a virus-free recombinant protein expression platform based on adeno-associated viral (AAV) elements that is capable of rapid and consistent production of complex antibody mixtures in a single batch format. Using both multiplexed immunoassays and cation exchange (CIEX) chromatography, cell culture supernatants generated using our system were assessed for stability of expression and ratios of the component antibodies over time. Cultures expressing combinations of three to ten antibodies maintained consistent expression levels and stable ratios of component antibodies for at least 60 days. Cultures showed remarkable reproducibility following cell banking, and AAV-based cultures showed higher stability and productivity than non-AAV based cultures. Therefore, this non-viral AAV-based expression platform represents a predictable, reproducible, quick and cost effective method to manufacture or quickly produce for preclinical testing recombinant antibody combination therapies and other recombinant protein mixtures.     

嵌合抗体研究进展

抗体在疾病诊断,治疗和预防中发挥着重要作用,近几年来将基因工程应用到抗体生产的基因工程抗体技术发展迅速,本就基因工程抗体中的重要组成部分－嵌合抗体的研究进展加以综述。