治疗性抗体药物研究与发展趋势

单克隆抗体技术的问世,使研究和生产治疗性单抗药物成为现实.随着基因工程技术的发展,新型的重组抗体技术也随之而生.人们可以利用DNA重组技术对鼠源抗体进行人源化改造、构建合成或半合成抗体库及噬菌体抗体库,从中筛选获得人源抗体,甚至利用转基因小鼠直接获得人源抗体.抗体药物发展的趋势也从鼠源、人一鼠嵌合、人源化到全人源.近年...     

抗肿瘤人源化抗体药物的研究进展

随着单克隆抗体技术的发展,治疗性抗体药物逐渐占据全球市场,主要应用于肿瘤治疗、抗移植排斥、自身免疫性疾病的治疗等。抗体药物可根据人源化程度不同,分为鼠源抗体、嵌合抗体、人源化抗体和全人源抗体。本文着眼于目前治疗性抗体药物研究热点,聚焦于抗肿瘤人源化抗体药物,结合已上市热点抗肿瘤人源化抗体药物实例,从抗体人源化技术以及人源化抗体生产的角度来阐述目前研究状况。同时,立足于国内外抗肿瘤人源化抗体药物的现状,分析未来发展趋势。     

单克隆抗体治疗制剂研究与应用

文本讨论了降低鼠单克隆抗体免疫原性的方法,采用嵌合抗体技术和互补决定区(CDR)稼接技术能使鼠源抗体部分人源化.此外,本文还介绍了治疗性单克隆抗体的研究现状.     

抗HER3单克隆抗体的人源化及成药性初步评价

目的构建人源化抗人表皮生长因子受体3(human epidermal growth factor receptor 3, HER3)单克隆抗体(单抗)并对其成药性进行初步评估。方法通过互补决定区(complementarity-determining region, CDR)移植对鼠抗HER3单抗进行人源化, 然后对骨架区一些位点氨基酸进行回复突变以恢复人源化抗体的亲和力。对重组表达的人源化抗体用聚乙二醇沉淀法检测其在不同缓冲液中的溶解度, 并通过测定内源荧光评估其高级结构。结果经CDR移植及回复突变的抗HER3人源化抗体具有与嵌合抗体相当的亲和力, 且人源化抗体具有较好的溶解度及典型的抗体内源荧光特性。结论成功人源化了鼠抗HER3单抗, 人源化后的抗体具有开发成临床药物的潜力。     

全人源单克隆抗体现状及发展趋势(续)

4 技术平台全人源单抗是抗体工程技术发展的重要趋势.目前全人源单抗的研发技术主要有:B细胞永生化技术、噬菌体抗体库技术、转基因小鼠技术以及人源杂交瘤技术等.其中以噬菌体展示技术和转基因小鼠技术实际应用最广泛、最成功.     

人源化抗体

杂交瘤技术使抗人病原体或细胞的啮齿动物单克隆抗体得以产生,但在临床上的应用有限。依靠啮齿动物抗体的“人源化”蛋白质工程技术现已能产生用于治疗传染病、自身免疫病和肿瘤的各种抗体。人源化抗体的药物动力学有所改善,免疫原性降低,有利于临床使用。     

人源化抗体

杂交瘤技术使抗人病原体或细胞的啮齿动物单克隆抗体得以产生，但在临床上的应用有限，依靠啮齿动物抗体的“人源化“蛋白质工程技术现已能产生用于治疗传染病，自身免疫病和肿瘤的各种抗体，人源化抗体的药物动力学有所改善，免疫原性降低，有利于临床使用。     

单克隆抗体在疾病治疗中的应用

单克隆抗体(单抗)技术与分子生物学技术的结合使重组嵌合抗体、人源化抗体和全人抗体的技术得到迅速发展.由于这些单抗带有人抗体的Fc片段,因此,这些抗体不仅能中和抗原,更重要的是能介导细胞毒作用和激活补体系统.这些抗体已被用于治疗某些疾病,如癌症、免疫性疾病、感染性疾病和器官移植排斥.随着大规模CHO细胞生产工艺的发展,越来越多的单抗将应用于临床.     

单克隆抗体在疾病治疗中的应用

单克隆抗体(单抗)技术与分子生物学技术的结合使重组嵌合抗体、人源化抗体和全人抗体的技术得到迅速发展.由于这些单抗带有人抗体的Fc片段,因此,这些抗体不仅能中和抗原,更重要的是能介导细胞毒作用和激活补体系统.这些抗体已被用于治疗某些疾病,如癌症、免疫性疾病、感染性疾病和器官移植排斥.随着大规模CHO细胞生产工艺的发展,越来越多的单抗将应用于临床.     

抗体药物研究进展与趋势*

自1986年第1个抗体药物OKT-3上市以来,抗体药物经历了20年的发展.在1986-1996年间,早期的鼠源抗体药物存在抗原性强、耐受性差的缺点,随后通过基因工程手段发展了低抗原性的嵌合抗体、人源化抗体.随着噬菌体呈现、大肠杆菌呈现、酵母呈现和核糖体呈现技术的成熟,最终通过体外筛选发展出了全人源抗体.抗体药物经历了早期10年的低谷期,1996年开始进入快速发展的轨道.在人源化抗体技术成熟后,进入临床试验的药物中抗体药物增长率显著高于小分子药物.同靶点类似抗体药物同时进入市场说明了抗体药物专利无法形成有效垄断.笔者概述了抗体药物的发展简史,列出自OKT-3上市以来美国FDA批准的用于诊断、预防、治疗的抗体药物,并对其中具有代表性的Vectibix与Humira进行了概述,并提出抗体药物现在所面临的4个方面的挑战.     

Monoclonal antibodies in the treatment of neuroimmunological diseases

Over the past 25 years, monoclonal antibodies (mAb) have become important elements in the therapeutic concepts for numerous clinical specialities, including oncology, gastroenterology, hemostaseology and endocrinology. One of the most dynamic fields of their use is the treatment of autoimmune diseases. Although the number of existing mAb interfering with the immune system has increased remarkably and many studies have yielded encouraging results in the treatment of neuroimmunological diseases, their clinical use is still limited compared with standard treatments. The only mAb which has been approved for a neuroimmunological disease by now is natalizumab for the treatment of relapsing-remitting multiple sclerosis (RRMS). This article gives an overview on mAb that are currently in use or under investigation for treating neuroimmunological diseases like multiple sclerosis (MS), neuromyelitis optica (NMO), chronic inflammatory demyelinating polyneuropathy (CIDP), inclusion body myositis (IBM), dermatomyositis, polymyositis, opsoclonusmyoclonus syndrome (OMS), multifocal motor neuropathy (MMN), anti-myelin-glycoprotein neuropathy (Anti-MAG), stiff person syndrome and myasthenia gravis (MG).     

Engineering and characterization of a mouse/human chimeric anti-phencyclidine monoclonal antibody

Previously, our laboratory produced a high affinity, anti-phencyclidine (PCP) murine monoclonal antibody (mAb6B5) that also binds other PCP-like arylcyclohexylamines. In this project, mAb6B5 is engineered into a mouse/human chimera (ch-mAb6B5) to assess the feasibility of developing it into a medication for PCP and PCP-like drug abuse. To create ch-mAb6B5, the light and heavy chain constant regions of mAb6B5 were replaced with human kappa and IgG(2) constant regions in order to decrease its potential immunogenicity in humans. To be an effective anti-PCP medication, ch-mAb6B5 must retain the critical immunochemical binding properties of mAb6B5. Expression vectors containing ch-mAb6B5 light chain and heavy chain cDNA were constructed and expressed in the murine myeloma cell line P3X63-Ag8.653. Immunoassays confirm that ch-mAb6B5 is indeed a chimera, composed of mAb6B5's PCP-binding variable domains and human kappa and IgG constant regions. Radioimmunoassays show that ch-mAb6B5 has the same drug-binding profile as mAb6B5. Ch-mAb6B5 and mAb6B5 bind PCP with a K(D) of 0.67 nM and 1.17 nM (respectively) and bind PCP-like arylcyclohexylamines 1-[1-(2-thienyl)cyclohexyl]piperidine and N-ethyl-1-phenylcyclohexylamine with similar specificity. Additionally, ch-mAb6B5 and mAb6B5 have the same calculated isoelectric points and molecular weights, critical properties in antigen-antibody interactions. These data demonstrate that mouse/human ch-mAb6B5, a "more human" version of murine mAb6B5, retains mAb6B5's unique drug-binding properties. This work supports our continued efforts to develop ch-mAb6B5 into a medication for PCP and PCP-like drug abuse - introducing the intriguing possibility of using a single therapeutic mAb for treating a class of abused drugs.     

Pharmacological modulation of GITRL/GITR system: therapeutic perspectives

Glucocorticoid-induced TNFR-related (gitr) is a gene coding for a member of the TNF receptor superfamily. GITR activation by its ligand (GITRL) influences the activity of effector and regulatory T cells, thus participating in the development of immune response against tumours and infectious agents, as well as in autoimmune and inflammatory diseases. Notably, treating animals with GITR-Fc fusion protein ameliorates autoimmune/inflammatory diseases while GITR triggering, by treatment with anti-GITR mAb, is effective in treating viral, bacterial and parasitic infections, as well in boosting immune response against tumours. GITR modulation has been indicated as one of the top 25 most promising research areas by the American National Cancer Institute, and a clinical trial testing the efficacy of an anti-GITR mAb in melanoma patients has been started. In this review, we summarize results regarding: (i) the mechanisms by which GITRL/GITR system modulates immune response; (ii) the structural and functional studies clearly demonstrating differences between GITRL/GITR systems of mice and humans; (iii) the molecules with pharmacological activities including anti-GITR mAbs, GITR-Fc and GITRL-Fc fusion proteins, GITRL in monomer or multimer conformation; and (iv) the possible risks deriving from GITRL/GITR system pharmacological modulation. In conclusion, GITR triggering and inhibition could be useful in treating tumours, infectious diseases, as well as autoimmune and inflammatory diseases. However, differences between mouse and human GITRL/GITR systems suggest that further preclinical studies are needed to better understand how safe therapeutic results can be obtained and to design appropriate clinical trials.     

Prevention of drug-induced memory impairment by immunopharmacotherapy

One approach to treating drug abuse uses antidrug antibodies to immunize subjects against the illicit substance rather than administering therapeutics that target the specific CNS site of action. At present, passive vaccination has recognized efficacy in treating certain gross symptoms of drug misuse, namely, motor activation, self-administration, and overdose. However, the potential for antibodies to prevent drug-induced changes involving finer cognitive processes, such as benzodiazepine-associated amnesia, remains unexplored. To address this concept, a flunitrazepam hapten was synthesized and employed in the generation of a panel of high affinity monoclonal antibodies. Anti-flunitrazepam mAb RCA3A3 ( K d,app = 200 nM) was tested in a mouse model of passive immunization and subsequent mole-equivalent challenge with flunitrazepam. Not only was flunitrazepam-induced sedation prevented but immunization also conferred protection to memory consolidation as assessed through contextual and cued fear conditioning paradigms. These results provide evidence that immunopharmacotherapeutic blockade of drug intoxication also preserves complex cognitive function.     

Importance of cynomolgus monkeys in development of monoclonal antibody drugs

Animal species used in the preclinical studies for development of monoclonal antibody (mAb) drugs are surveyed in this review. Relevant animal species for preclinical studies of mAb candidates are those express desired epitope of mAb candidates. Cynomolgus monkeys cross-react with mAb drugs much higher than other animal species commonly used in preclinical studies such as absorption, distribution, metabolism and excretion (ADME), efficacy, and toxicity studies, for development of new drugs. Moreover, plasma exposure of the mAb drugs in humans is predicted well from the exposure in the monkeys, and the placental transfer of immunoglobulin G (IgG, all the mAb drugs contain IgG) from mother to fetus is similar between humans and the monkeys from a viewpoint of time course and plasma level of IgG transferred. These observed findings indicate that the monkeys are the most suitable animal species used in the ADME and toxicity studies for development of new mAb drugs.     

Modulation of antigen-specific T cell response by a non-mitogenic anti-CD3 antibody

Suppression of T cell response is the key to enhance graft survival and control autoimmune diseases. A mitogenic anti-CD3 monoclonal antibody (mAb), OKT3, has been used for decades to control acute rejection in organ transplantation. Although effective, the clinical use was limited by its side effects, such as cytokine release mediated by T cell activation. A low mitogenic humanized OKT3 with reduced FcR-binding (hgammaOKT3 Ala-Ala) was generated and tested in several clinical studies. Although hgammaOKT3 Ala-Ala demonstrated maintained efficacy and better safety it still activated T cells. To investigate if a non-mitogenic anti-CD3 mAb can be equally effective in immune suppression, a chimeric non-FcR-binding anti-mouse CD3 mAb (anti-CD3 IgG2a Ala-Ala) was generated. Unlike the hgammaOKT3 Ala-Ala, the mouse IgG2a Ala-Ala anti-CD3 mAb did not induce T cell activation as measured by proliferation, cytokine production and apoptosis. Nevertheless, the IgG2a Ala-Ala anti-CD3 mAb was equally effective in the inhibition of antigen-specific CD4+ T cell activation in vitro to that of the mitogenic anti-CD3 mAb (Anti-CD3 IgG2a). In vivo, the IgG2a Ala-Ala anti-CD3 mAb only induced transient reduction of peripheral and spleen T cells and did not trigger detectable cytokine release. Nonetheless, this non-mitogenic anti-CD3 mAb significantly prolonged islet graft survival as effectively as the mitogenic anti-CD3 mAb in an allogenic islet transplantation model. These results demonstrated that a non-mitogenic anti-CD3 mAb could be used as an effective immune modulator. It may also indicate that a true non-mitogenic version of OKT3 could further improve its safety profile for clinical use.     

Function characterization of a glyco-engineered anti-EGFR monoclonal antibody cetuximab in vitro

Aim:

To evaluate the biochemical features and activities of a glyco-engineered form of the anti-human epidermal growth factor receptor monoclonal antibody (EGFR mAb) cetuximab in vitro.

Methods:

The genes encoding the Chinese hamster bisecting glycosylation enzyme (GnTIII) and anti-human EGFR mAb were cloned and coexpressed in CHO DG44 cells. The bisecting-glycosylated recombinant EGFR mAb (bisec-EGFR mAb) produced by these cells was characterized with regard to its glycan profile, antiproliferative activity, Fc receptor binding affinity and cell lysis capability. The content of galactose-α-1,3-galactose (α-Gal) in the bisec-EGFR mAb was measured using HPAEC-PAD.

Results:

The bisec-EGFR mAb had a higher content of bisecting N-acetylglucosamine residues. Compared to the wild type EGFR mAb, the bisec-EGFR mAb exhibited 3-fold higher cell lysis capability in the antibody-dependent cellular cytotoxicity assay, and 1.36-fold higher antiproliferative activity against the human epidermoid carcinoma line A431. Furthermore, the bisec-EGFR mAb had a higher binding affinity for human FcγRIa and FcγRIIIa-158F than the wild type EGFR mAb. Moreover, α-Gal, which was responsible for cetuximab-induced hypersensitivity reactions, was not detected in the bisec-EGFR mAb.

Conclusion:

The glyco-engineered EGFR mAb with more bisecting modifications and lower α-Gal content than the approved therapeutic antibody Erbitux shows improved functionality in vitro, and requires in vivo validations.     

Epitope-Dependent Selective Targeting of Thrombomodulin Monoclonal Antibodies to Either Surface or Intracellular Compartment of Endothelial Cells

Abstract

Internalization of antibodies to thrombomodulin (TM) may provide a mechanism for intraendothelial targeting of drugs or genes. This study characterized three monoclonal antibodies against human TM (mAb 1009,1029, and 1045) and examined their internalization by human umbilical vein endothelial cells (HUVEC). It assessed binding of antibodies to recombinant human TM containing chondroitin sulfate (complete, cTM) and TM lacking chondroitin sulfate (incomplete, iTM). Direct RIA, indirect RIA, and ELISA and competitive ELISA show that (1) mAb 1009 binds to both cTM and iTM independently of divalent cations; (2) binding of mAb 1029 to iTM requires divalent cations, while binding to cTM is cation-independent; (3) mAb 1045 binds selectively to cTM independently of divalent cations. Binding of all three antibodies to the surface TM in HUVEC at 4°C was similar by indirect immunostaining. In permeabilized HUVEC, however, mAb 1009 and 1029 provide brighter intracellular staining than mAb 1045. Uptake of ¹²⁵I-mAb 1009 by HUVEC at 37°C was significantly higher than that of ¹²⁵I-mAb 1045. Low temperature markedly suppresses binding of ¹²⁵I-mAb 1009 to HUVEC, but has no effect on ¹²⁵I-mAb 1045 binding. About 80% of radiolabeled mAb 1045 bound to HUVEC at 37°C could be eluted by acidic buffer from the cell surface, but only 40% of mAb 1009 and 1029 was elutable at these conditions. About 70-80 % of ¹²⁵I in cell lysates was TCA-soluble after HUVEC incubation with either mAb 1009 and 1029, but only 10 and 2.5% of ¹²⁵I was TCA-soluble in cell lysates and medium after 90 min incubation with ¹²⁵I-mAb 1045 at 37°C. Therefore, HUVEC internalize and degrade an mAb that reacts with iTM, yet do not internalize an mAb that reacts selectively with cTM (mAb 1045). This result implies that either HUVEC do not internalize cTM constitutively or mAb 1045 suppresses TM internalization. Therefore, antibodies recognizing different TM epitopes might provide targeting of drugs to different cellular compartments.     

Monoclonal antibody:the corner stone of modern biotherapeutics

Worldwide sales of biologic drugs exceeded 100 billion USD in 2011.About 32% is from therapeutic monoclonal antibody(mAb).With many blockbuster biopharmaceutical patents expiring over the next decade,there is a great opportunity for biosimilar to enter the worldwide especially emerging market.Both European Medicines Agency(EMA) and Food and Drug Administration(FDA) have introduced regulatory frameworks for the potential approval of biosimilar mAb therapeutics.Rather than providing a highly abbreviated path,as in the case for small molecule chemical drug,approval for biosimilar mAb will require clinical trial and the details will be very much on a case-by-case basis.Since mAb is the dominant category of biologic drugs,mAb will be the focus of this review.First,the United States(US) and European Union(EU) approved mAb and those in phase 3 trials will be reviewed,then strategies on how to win biosimilar competition will be reviewed.     

治疗性抗狂犬病病毒抗体研究进展

狂犬病病毒(rabies virus,RV)感染后的致死率极高,为了替代用于RV暴露后预防的马抗RV免疫球蛋白和人抗RV免疫球蛋白,人们正在进行相关单克隆抗体(单抗)的研究.此文主要阐述了治疗性单抗CR57及其互补单抗CR40987,并讨论了抗RV单抗的表达系统.