抗肿瘤抗体药物研究进展

自1997年以来,抗体药物用于肿瘤治疗取得突破性的进展。据统计,国内外已有约17种抗体药物被批准用于临床肿瘤治疗。除了一直比较成功的裸抗体,抗体药物偶联物(ADC)成为抗肿瘤抗体药物研发的新热点。抗原靶标及作用机制特点决定了抗肿瘤抗体药物在临床的安全性和疗效。本文主要从肿瘤细胞杀伤机制、作为抗体靶标的肿瘤抗原、在临床的应用情况及ADC纳米粒研究方面对抗肿瘤抗体药物进行了综述。     

Treatment of acute leukaemias with monoclonal antibodies: current status and future prospects

Monoclonal antibodies are a new class of agents targeted at specific receptors on cancer cells. In addition to direct cellular effects, antibodies can carry substances to the targeted cells, such as radioactive isotopes, toxins, and antineoplastic agents. At present monoclonal antibodies, directed against both lymphoid antigens (CD 20 and CD 52) and a myeloid antigen (CD33) are available for clinical use. In ALL, rituximab, a humanized anti CD20 antibody, has been combined to chemotherapy mainly in mature B-ALL and Burkitt's lymphoma and preliminary results are promising. Alemtuzumab is an anti-CD52 humanized antibody, which showed anti-tumour activity in CLL; clinical effects were observed in some patients with relapsed adult ALL. Monoclonal antibodies against myeloid antigens have been prevalently used in acute myeloid leukaemias (AML), where the most utilised immunological target is CD33. The CD33 molecule is expressed by approximately 90% of AMLs but not on CD34(+) bone marrow-resident hematopoietic stem cells. The humanized anti-CD33 monoclonal antibody HuM195 has only modest activity against overt AML, but it can eliminate minimal residual disease. Radioimmunotherapy with beta-particle-emitting isotopes targeting CD33 shows a major efficacy. Targeted chemotherapy with the anti-CD33-calicheamicin construct gemtuzumab ozogamicin (GO) has produced remissions as a single agent in patients with relapsed AML and appears promising when used in combination with standard chemotherapy. GO is composed of a humanized immunoglobulin G(4) (IgG(4)) monoclonal antibody (mAb), targeting the CD33 antigen and linked to a calicheamicin derivative, a cytotoxic anthracycline antibiotic. GO has been approved by FDA as second-line therapy in older patients with AML. The most common adverse effects of monoclonal antibodies are myelosuppression, infusion-related reactions, and hypersensitivity reactions. Rituximab may cause tumour lysis syndrome. Alemtuzumab causes immunosuppression, increasing the risk of infection. GO may cause hepatotoxicity.     

抗肿瘤抗体偶联药物靶向递送的研究进展

抗体与抗原结合的靶向递送是一种精准的递药方式,由于其高特异性和亲和力被视为理想的靶向递药方式之一,这为成功解决抗肿瘤治疗中化疗药物选择性差的问题开辟了新的道路。当前,利用单克隆抗体与靶抗原结合的抗体偶联药物(antibody drug conjugates,ADCs)研究成为分子靶向治疗的研究热点,本文就ADCs靶向递送的作用机制、靶向策略和靶向递送进展进行综述,以期为临床开发新的ADCs提供参考。     

Monoclonal antibodies for the treatment of acute myeloid leukemia

Currently, patients with acute myeloid leukemia (AML) are treated with cytotoxic chemotherapy and hematopoietic stem cell transplantation (HSCT). With this approach, the majority of patients still die of their disease because of both treatment-related mortality and relapse. Recently, monoclonal antibodies and immunoconjugates have been developed which potentially may increase the efficacy of treatment and decrease morbidity and mortality by specifically targeting the malignant cell. Unconjugated monoclonal antibodies have shown only moderate activity. A second, more effective, approach involves antibody conjugation with radioactive particles or chemotherapeutic agents, such as, immunotoxins, targeted delivery of cell killing. The antigens CD33, CD45, and CD66, are three antigens to which monoclonal antibodies have been directed. Most experience has been with gemtuzumab ozogamicin (Mylotarg) which is an immunoconjugate of an anti-CD33 antibody chemically linked to a potent cytotoxic agent, calicheamicin. Gemtuzumab ozogamicin appears to be particularly active in patients with acute promyelocytic leukemia, possibly related to the high expression of the CD33 antigen on the cell surface. Although gemtuzumab ozogamicin has activity as a single agent, the most promising result may be seen when this agent is combined with conventional cytotoxic chemotherapy. Preliminary studies have suggested a high complete remission rate and randomized clinical trials are underway. A unique potential toxicity has been identified, namely venoocclusive disease or sinusoidal obstructive syndrome which may be problematic among patients who subsequently undergo HSCT. An additional strategy includes radiolabeled monoclonal antibodies to intensify the conditioning regimen prior to HSCT. The most promising results have been obtained with radiolabeled anti-CD45 antibodies.     

Urinary antigens as markers of papillary toxicity. I Identification and characterization of rat kidney papillary antigens with monoclonal antibodies

Monoclonal antibodies were prepared in an attempt to develop diagnostic tools for the identification of toxic damage to the rat renal papilla. One IgG and five IgM monoclonal antibodies, reacting with antigens localized in the papilla were obtained. Three of the IgM class and the IgG class monoclonal antibodies were found to be specific for antigens localized in collecting ducts, two of them staining papillary collecting ducts more intensely than cortical collecting ducts. The IgG class antibody, termed Pap X 5C10, recognizes an antigen located at high density on the luminal side of papillary collecting duct epithelial cells and at lower density in cortical collecting duct cells. One of the IgM class monoclonal antibodies reacts with an antigen localized in epithelial cells of ascending and descending loops of Henle and of connecting tubules. Another of the IgM class monoclonal antibodies reacts with an antigen localized in the interstices of the inner medulla. All these monoclonal antibodies react with their antigens in native frozen as well as in Bouin-fixed and paraffin-embedded tissue slices. Molecular properties of the Pap X 5C10 antigen have been investigated by gel permeation chromatography, SDS-PAGE, Western blotting, and isoelectric focusing. The results indicate that the antigen in both its tissue-derived and urinary form is of large (150–200 kDa) molecular size and can be separated into two molecular species with isoelectric points of pH 7.2 and 7.3 respectively. In the urine the antigens recognized by the monoclonal antibodies form large complexes with Tamm-Horsfall protein. The antigen-containing complexes can be extracted from urine by adsorption to diatomaceous earth and elution with SDS-containing buffer. Using sandwich ELISA-type assays it is possible to determine the concentration of the antigens. In preliminary experiments we were able to show that at least three of the antigens are detected in the urine following toxic insults to the kidney. The monoclonal antibodies prepared and the tests developed thus may provide direct diagnostic access to the renal papilla and allow, for the first time, early detection of papillary damage. Received: 14 May 1996/Accepted: 19 July 1996     

Immunoscreening protocols for the identification of clinically useful antibodies and antigens

The antigen-antibody interaction is a powerful tool for the immuno-screening of several diseases, including cancer and genetic disorders. The high specificity of monoclonal antibodies (mAbs) enables them to target antigens and form complexes that can be detected with enzymes, radionuclides, fluorescent dyes or other markers. The antibody molecule, which has an antigen binding site, can be used as an intact molecule or as a fragment, for example, F(ab)(2), Fab, Fv or scFv. Similarly, the antigen can also be varied. In this review, immuno-screening techniques that can be used to detect clinically relevant antibody-antigen interactions will be discussed.     

No specific reactivity to E. coli glutamic acid decarboxylase from sera of newly-diagnosed insulin dependent diabetic patients

The 65 kD isoform of Glutamic Acid Decarboxylase (GAD), is one of the major autoantigens in human type 1 diabetes mellitus. This enzyme shares amino acid identity, in select regions already determined as antigenic with its counterpart from E. coli. We tested the reactivity of diabetic and normal sera and an E. coli GAD-specific monoclonal antibody (2D9) to E. coli GAD by solid phase and competition ELISA, as well as immunoblotting to check for cross-reactivity of autoantibodies to the two antigens. Specific antibodies for E. coli GAD are present in diabetics and normal subjects without any differences in frequency and titer. The reactivity of such antibodies in ELISA could be blocked in a dose-dependent manner by the addition of excess antigen in the liquid phase. Furthermore, the monoclonal antibody against E. coli GAD does not recognise human recombinant GAD65 in an ELISA. We conclude that there is no basis for cross-reactivity between the two antigens, and antibody reactivity to GAD65 in man cannot arise from cross-reactivity to the E. coli enzyme.     

Separation of antigens and antibodies by immunoaffinity chromatography

Context: Affinity chromatography is an efficient antibody, antigen and protein separation method based on the interaction between specific immobilized ligands and target antibody, antigen, and so on. Populations of available ligands can be used to separate antibodies or their Fab fragments. Similarly, antigens can be isolated by immunoaffinity chromatography (IAC) on immobilized antibodies of low affinity.

Objective: This review describes the advantages, the applications, as well as the drawbacks, of IAC in the separation and purification of antibodies and antigens.

Methods: The present review discussed all types of purification and isolation of antibodies and antigens by IAC, including purification of antibodies using immobilized and synthetic mimic proteins A, G and L; isolation of Fab fragments of antibodies; separation of antibodies against different antigen forms; isolation of antigens by immobilized antibodies and so on. These methods come from over 60 references compiled from all major databases.

Results: Purification of antigens with antibodies should choose low-affinity antibodies to avoid denaturation of most proteins. Concern for cost and safety, prompted research activities focused on novel synthetic ligands with improved properties such as lower cost, avoidance of the risk of contamination associated with natural ligands of human or animal origin to isolate antibodies and antigens.

Conclusion: It is anticipated that the improvements of IAC will have impact not only on large-scale production of antibodies but also on the generation of new affinity-based methods for the increasing number of proteins and antibody derivatives available by protein engineering and the proteomics revolution.     

Therapeutic monoclonal antibody concentration monitoring: free or total?

Most therapeutic monoclonal antibodies are designed to bind a specific antigen to elicit pharmacological effects. Accurate quantification of a therapeutic monoclonal antibody in biological matrices is essential for assessing its pharmacokinetics and selecting an effective dosing regimen. Therapeutic antibodies may exist in free, partially bound and fully bound forms in the bloodstream. The choice of which form(s) to measure and how to measure them is gaining much attention with the increase in the number of soluble therapeutic targets. This article will review the bioanalytical methods used in supporting the clinical development of the US FDA-approved therapeutic monoclonal antibodies and also discuss how different factors, such as assay format, target and antibody concentrations, and sample dilutions, can have an impact on the measurement of each form of antibody. Appreciation of which form of drug is being measured and what factors may impact measurement under different conditions are important for interpretation of the pharmacokinetics of therapeutic antibodies.     

Drug delivery systems--2. Site-specific drug delivery utilizing monoclonal antibodies

Monoclonal antibodies (MAbs) are purified antibodies produced by a single clone of cells. They are engineered to recognize and bind to a single specific antigen. Accordingly, when administered, MAbs home in on a particular circulating protein or on cells that bear the correct antigenic signature on their surfaces. It is the specificity of MAbs that has made them valuable tools for health professions. Following the discovery of Kohler and Milstein regarding the method of somatic cell hybridization, a number of investigators have successfully adopted this technique to obtain T-lymphocyte hybrid cell lines by fusion of activated T (thymus derived) lymphocytes with a T lymphoma cell line leading to an immortalization of a specific differentiated function. The hybrids thus obtained were subsequently shown to produce homogeneous effector molecules with a wide variety of immune functions such as enhancement or suppression of antibody responses, generation of helper T cells, suppressor T cells and cytotoxic T cells. Study of these regulatory molecules has been further shown to provide a greater insight into the genetic, biochemical and molecular mechanisms responsible for cellular development, and the interaction and triggering of various cell types. The successful application of hybridoma technology has now resulted into several advances in the understanding the mechanism and treatment of diseases, especially cancer and development of vaccines, promotion of organ transplantation and therapy against parasites as well. Since monoclonal antibodies could be made in unlimited supply, they have been used in genetic studies such as mRNA and gene isolation, chromosomal isolation of specific genes, immunoglobulin structure, detection of new or rare immunoglobulin gene products, structural studies of enzymes and other proteins and structural and population studies of protein polymorphisms. In some instances, the monoclonal antibodies have been found to replace conventional antisera for studies of chromosome structure and function, gene mapping, embryogenesis, characterization and biosynthesis of developmental and differentiation antigens. These antigens are those that are specific for various cell types and tissues, species specific antigen, antigens involved in chemotaxis, immunogenetics and clinical genetics including genetically inherited disorders, chromosome aberrations and transplantation antigens. Besides these monoclonal antibodies, their complexes have recently been investigated as exquisitely sensitive probes to be guided to target cells or organs. They have been used to deliver cytotoxic drugs to malignant cells or enzymes to specific cell types.(ABSTRACT TRUNCATED AT 400 WORDS)     

Elimination mechanisms of therapeutic monoclonal antibodies

Targeted therapies using monoclonal antibodies have achieved important therapeutic applications in the treatment of various human diseases. Understanding the factors that impact the pharmacokinetics of monoclonal antibodies is of high importance for effective therapy. Many factors related to the target antigen, antibody and patients can affect antibody elimination. Evaluation of these factors will facilitate the understanding of the processes involved in antibody elimination.     

治疗性抗体的基础研究

抗体的靶向性提供了一个改进治疗制剂选择性的方法 .由于大部分抗原均可诱生抗体 ,因此抗体应用的潜力是巨大的 .临床上正用于治疗肿瘤 ,病毒感染 ,自身免疫病 ,中毒性休克 ,再狭窄 ,Rh溶血症和抗移植排斥等 .但单克隆抗体的临床应用受一定限制 ,主要障碍是诱导产生人抗鼠抗体(HAMA反应 ) ,肿瘤参入量低 ,亲和力低和半衰期短等 .然而 ,利用分子生物学技术能克服这些障碍 ,改善临床效果     

柯萨奇病毒A组10型抗原双抗体夹心ELISA定量方法的建立及应用

目的 建立柯萨奇病毒A组10型（coxsackievirus A10,CV-A10）抗原双抗体夹心ELISA定量检测方法,用于CV-A10生产过程样品和四价手足口病疫苗的质量控制。方法  以纯化的CV-A10抗原分别免疫绵羊和小鼠获得羊免疫血清和杂交瘤单克隆抗体(单抗)细胞株,以杂交瘤细胞株免疫小鼠制备腹水,羊血清和小鼠腹水分别经亲和层析后获得纯化羊抗CV-A10多克隆抗体（多抗）和小鼠抗CV-A10单抗。采用微量细胞病变法测定纯化多抗和单抗中和抗体效价。分别以纯化羊多抗作为包被抗体、小鼠单抗作为检测抗体,进行配对筛选研究,建立CV-A10抗原定量双抗体夹心ELISA;对方法的线性、专属性、准确度、精密度、范围进行验证,并对CV-A10抗原生产过程中的样品和成品进行检测。结果 纯化抗CV-A10单抗和多抗均具有中和抗体活性。以多抗作为包被抗体、7株单抗作为检测抗体进行配对,其中5株单抗配对成功,选择CY166-14R作为检测抗体用于CV-A10抗原定量检测ELISA的建立;对检测方法进行优化,确定以羊多抗作为包被抗体的使用稀释比例为1：5 000〜1：10 000、小鼠单抗检测抗体稀释比例1 ：2 000〜1：4 000。建立的CV-A10抗原定量检测方法范围为0.42〜10. 00 U/ml,线性决定系数≥0. 99;该方法仅能特异性检测CV-A10抗原,与其他抗原或物质（肠道病毒71型、CV-A6、CV-A16、M199、DMEM、Vero细胞蛋白、牛血清）无交叉反应;对高、中、低浓度样品进行测定,测定值/理论值在95%〜110%之间,相对标准偏差在15%以内。结论 建立了 CV-A10抗原定量双抗体夹心ELISA,该方法在一定范围内的线性、专属性、准确度、精密度均较好,可用于CV-A10抗原生产过程样品和成品的质量控制,为CV-A10抗原的体外效力评价提供方法学基础。     

抗肿瘤单克隆抗体药物研究进展

抗肿瘤细胞表面抗原的单克隆抗体(单抗)可以有效治疗肿瘤.这些单抗药物可通过直接作用于肿瘤细胞、改变机体免疫应答、运送药物和重新激发机体免疫等机制来抗击肿瘤.此文就单抗治疗肿瘤的作用靶点、机制、代表性药物和新策略进行综述.     

Urinary antigens as markers of papillary toxicity. II: Application of monoclonal antibodies for the determination of papillary antigens in rat urine

We have previously reported the preparation of monoclonal antibodies specific for antigens localized in the rat renal papilla. Three of the monoclonal antibodies reacting with antigens localized in papillary and cortical collecting duct epithelia were selected for the development of enzyme-linked immunosorbent assay (ELISA)-type assays. The papillary antigens (`PapA') determined in these tests were designated PapA1 (applying the monoclonal antibody PapX 5C10), PapA2 (applying the monoclonal antibody PapX 12F6), and PapA3 (applying the monoclonal antibody PapXI 3C7). Using these assays antigen excretion was determined in the urine of rats. Depending on the test compound used, the application route, and the dose, the observed antigen release patterns differed. Whereas after a single intraperitoneal application of 2-bromoethanamine or of propyleneimine an increased release of PapA1 but not of the two other antigens was observed oral application of bromoethanamine had minor effects. In contrast, both a single intraperitoneal application or repeated oral applications of indomethacin resulted in an increased release of all the three antigens. Daily application of ipsapirone in the diet or in drinking water resulted in significantly elevated urinary release of PapA1 which increased incrementally for the duration of the application. Release of PapA2 and PapA3 was not affected and remained in the normal range. These results show that with the tests developed changes in the rat renal papilla caused by xenobiotics can be detected early by urinary analysis and monitored during follow-up studies. Moreover, the different antigen release patterns obtained after application of the different compounds suggest a possible differing mode of action. Received: 16 November 1998 / Accepted: 13 April 1999     

双特异性抗体在复发难治多发性骨髓瘤中的治疗进展

近年来, 针对多发性骨髓瘤(multiple myeloma, MM)细胞上特异性表面抗原的单克隆抗体越来越多应用于治疗复发难治多发性骨髓瘤(relapsed/refractory multiple myeloma, R/RMM)。双特异性抗体(bispecific antibodies, BsAb)与肿瘤细胞抗原和T细胞上的CD3结合, 激活T细胞并靶向杀伤肿瘤细胞, 有针对B细胞成熟抗原(B cell maturation antigen, BCMA)靶点和非BCMA靶点如GPRC5D和FcRH5的多种BsAb, 显示各自的药代动力特点以及相关疗效和不良反应, 多项临床试验研究已证实其在R/RMM患者中具有可喜的临床有效性和安全性。     

Preclinical and clinical safety of monoclonal antibodies

Owing to their unique specificity, monoclonal antibodies have provided a novel approach to the treatment of human diseases. Several types of antibodies against a diverse array of pharmacological targets have been marketed and many more are currently in clinical trials. Factors related to antigen expression, target pharmacology, and antibody effector functions can contribute to the adverse event profiles observed with monoclonal antibodies. Effective translation of information gained from preclinical research and safety studies into clinical development is a crucial step for successful development of monoclonal antibodies.     

Targeting novel antigens for prostate cancer treatment: focus on prostate-specific membrane antigen

Prostate-specific membrane antigen (PSMA) is a relatively omnipresent, but unique Type II dimeric transmembrane protein with a multiplicity of functions and has been shown to be a reasonable target for immunological approaches such as vaccines or more directed therapy with radioactively labelled monoclonal antibodies against PSMA. Given the abundance of various glycoprotein and carbohydrate antigens expressed on the surface of prostate cancer cells and cell lines, PSMA stands out as another ‘self’ antigen which is not only expressed on cancer cells, but on neovasculature. Although vaccines are varied in their design and target goal, recent technology has afforded researchers the opportunity to induce recruitment of multiple effector cell populations, cytokines and factors which can elicit both cellular and humoral responses. This review serves to present unique approaches in vaccine development which can induce immunological responsiveness with potential impact on disease progression and to introduce PSMA as a poten-tial target for multimodality therapies.     

Targeting novel antigens for prostate cancer treatment: focus on prostate-specific membrane antigen

Prostate-specific membrane antigen (PSMA) is a relatively omnipresent, but unique Type II dimeric transmembrane protein with a multiplicity of functions and has been shown to be a reasonable target for immunological approaches such as vaccines or more directed therapy with radioactively labelled monoclonal antibodies against PSMA. Given the abundance of various glycoprotein and carbohydrate antigens expressed on the surface of prostate cancer cells and cell lines, PSMA stands out as another 'self' antigen which is not only expressed on cancer cells, but on neovasculature. Although vaccines are varied in their design and target goal, recent technology has afforded researchers the opportunity to induce recruitment of multiple effector cell populations, cytokines and factors which can elicit both cellular and humoral responses. This review serves to present unique approaches in vaccine development which can induce immunological responsiveness with potential impact on disease progression and to introduce PSMA as a potential target for multimodality therapies.     

Factors influencing the choice of monoclonal antibodies for antibody–drug conjugates

In antibody–drug conjugates (ADCs), monoclonal antibodies (mAbs) act as carriers for a cytotoxic payload providing the therapy with targeted action against cells expressing a target cell surface antigen. An appropriate choice of mAb is crucial to developing a successful ADC for clinical development. However, problems such as immunogenicity, poor pharmacokinetic (PK) and pharmacodynamic (PD) profiles and variable drug–antibody ratios (DARs) plague ADCs. In this review, we detail recent mAb-based innovations and factors that should be considered to overcome these problems to achieve a new generation of more effective ADC therapeutics.