Monoclonal antibody therapy in multiple sclerosis

Therapeutic approaches to multiple sclerosis (MS) are based on altering the functions of the immune system, either by using broad immunosuppressive drugs used for transplantation rejection and rheumatology, or by modulating them more discreetly with beta interferon and synthetic amino-acid copolymers. These strategies are only partially successful, have important safety and tolerability limitations, and have shown to be mostly effective in earlier stages of the disease, in which acute relapses dominate the clinical picture. For progressive phenotypes of MS there are currently no effective therapeutic options. As very specific and potent immunosuppressive agents, monoclonal antibodies (mAbs) may offer considerable advantages over other therapies for MS. During the last decade, anti-a4 integrin natalizumab became the first approved mAb for treatment of relapsing MS, after convincingly demonstrating clinically significant effects on two large Phase 3 trials. Moreover, the concept of disease remission was introduced for the first time, to describe patients that show no signs of clinical or imaging markers of disease activity during therapy with natalizumab. Of the mAbs under development for MS, alemtuzumab and rituximab have also shown promising evidence of effectiveness, and potentially expanded the therapeutic horizon to reversal of disease progression in early relapsing patients, and progressive patients who previously had not been studied. However, the appearance of progressive multifocal leukoencephalopathy (PML) in natalizumab-treated MS patients, as well as in patients with lymphoma, lupus and rheumatoid arthritis treated with rituximab, and autoimmune-type complications in alemtuzumab-treated MS patients underlines the fact that extended efficacy comes with significant clinical risks. The challenge is then how best to utilize therapies that have evidently superior efficacy in a chronic disease of young adults, to obtain the best benefit-risk ratio, and how to monitor and prevent emergent safety concerns.     

Monoclonal antibody therapy of chronic lymphocytic leukemia

Cure of patients with chronic lymphocytic leukemia (CLL) has been an elusive goal. The recent availability of active monoclonal antibodies has rekindled enthusiasm for new and innovative therapeutic approaches. Alemtuzumab, induces responses in about a third of patients with relapsed or refractory CLL following therapy with fludarabine and an alkylating agent. Whereas, rituximab has limited activity in previously treated patients, response rates of 50-70% have been reported in those without prior therapy. Recent data on combinations with rituximab and chemotherapy have shown promise for improving patient outcome. Newer antibodies in development include the primatized monoclonal antibody lumiliximab (IDEC-152), directed against CD23. Other biological approaches include the use of antisense oligonucleotides, proapoptic small molecules, and vaccines directed against the malignant B cells. The rational development of combinations of these promising approaches may eliminate the need for chemotherapy, leading to safer and more effective approaches for patients with CLL.     

Monoclonal antibody as therapy for malignant lymphomas

Rituximab was the first monoclonal antibody to have been registered for the treatment of B-cell lymphomas. Randomized studies have demonstrated its activity in follicular lymphoma, mantle-cell lymphoma, and diffuse large B-cell lymphoma in untreated or relapsing patients. Because of its high activity and low toxicity ratio, rituximab has transformed the outcome of patients with B-cell lymphoma. A combination of rituximab plus chemotherapy, R-CHOP, has the highest efficacy ever described with any chemotherapy in diffuse large B-cell lymphoma and follicular lymphoma. The role of radio-labelled antibodies is still to be defined.     

Monoclonal antibody drug immunoconjugates for targeted treatment of cancer

Monoclonal antibodies (mAb) directed to tumor-associated antigens (TAA) or antigens differentially expressed on the tumor vasculature have been covalently linked to drugs that have different mechanisms of action and various levels of potency. The use of these mAb immunoconjugates to selectively deliver drugs to tumors has the potential to both improve antitumor efficacy and reduce the systemic toxicity of therapy. Several immunoconjugates, particularly those that incorporate internalizing antibodies and tumor-selective linkers, have demonstrated impressive activity in preclinical models. Immunoconjugates that deliver doxorubicin, maytansine and calicheamicin are currently being evaluated in clinical trials. The feasibility of using immunoconjugates as cancer therapeutics has been clearly demonstrated. Gemtuzumab ozogamicin, a calicheamicin conjugate that targets CD33, has recently been approved by the Food and Drug Administration (FDA) for treatment of acute myelogenous leukemia (AML). This review concentrates on the properties of the tumor and the characteristics of the mAb, linker, and drugs that influence the efficacy, potency, and selectivity of immunconjugates selected for cancer treatment.     

Monoclonal antibodies as therapeutic agents in oncology and antibody gene therapy

Antibodies as therapeutic agents are mostly used in oncology,as illustrated by their applications in lymphoma,breastcancer or colorectal cancer.This review provides a brief historical sketch of the development of monoclonal antibodiesfor cancer treatment and Summarizes the most significant clinical data for the best-established reagents to date.It alsodiscusses strategies to improve the anti-rumor efficacy of antibody therapy,including antibody gene therapy and exploi-tation of bone marrow derived primary mesenchymal stem cells as the antibody gene transporter.     

Monoclonal antibody therapy in multiple sclerosis: Paradigm shifts and emerging challenges

Therapeutic approaches to multiple sclerosis (MS) are based on altering the functions of the immune system, either by using broad immunosuppressive drugs used for transplantation rejection and rheumatology, or by modulating them more discreetly with beta interferon and synthetic amino-acid copolymers. These strategies are only partially successful, have important safety and tolerability limitations, and have shown to be mostly effective in earlier stages of the disease, in which acute relapses dominate the clinical picture. For progressive phenotypes of MS there are currently no effective therapeutic options. As very specific and potent immunosuppressive agents, monoclonal antibodies (mAbs) may offer considerable advantages over other therapies for MS. During the last decade, anti-a4 integrin natalizumab became the first approved mAb for treatment of relapsing MS, after convincingly demonstrating clinically significant effects on two large Phase 3 trials. Moreover, the concept of disease remission was introduced for the first time to describe patients who show no signs of clinical or imaging markers of disease activity during therapy with natalizumab. Of the mAbs under development for MS, alemtuzumab and rituximab have also shown promising evidence of effectiveness and potentially expanded the therapeutic horizon to reversal of disease progression in early relapsing patients and progressive patients who previously had not been studied. However, the appearance of progressive multifocal leukoencephalopathy (PML) in natalizumab-treated MS patients, as well as in patients with lymphoma, lupus and rheumatoid arthritis, treated with rituximab and autoimmune-type complications in alemtuzumab-treated MS patients underlines the fact that extended efficacy comes with significant clinical risks. The challenge is then how best to utilize therapies that have evidently superior efficacy in a chronic disease of young adults to obtain the best benefit-risk ratio and how to monitor and prevent emergent safety concerns.Key words: monoclonal, antibody, multiple sclerosis, therapy, natalizumab, rituximab, alemtuzumab     

Monoclonal antibody specific for lactosylceramide

The mouse hybridoma line T5A7 was derived during studies aimed at mapping human myeloid differentiation antigens. The IgM antibody secreted by this line recognizes an antigen richly expressed on mature myelomonocytic cells and on a subpopulation of lectin-activated human T-lymphocytes (Andrews, R. G., Torok-Storb, B., and Bernstein, I. D. (1983) Blood 62, 124-132). In the present study, we have determined the specificity of T5A7 antibody to be directed to lactosylceramide (Gal beta 1----4Glc beta 1----1 Cer) based on direct and indirect binding assays using a variety of glycolipids with known structures. The antibody did not cross-react with glycolipids having an N-acetyllactosamine terminus, including lactoneotetraosylceramide lactonorhexaosylceramide (i antigen), and lactoisooctaosylceramide (I antigen). The possible contribution of ceramide to the reactivity of lactosylceramide with this antibody was also studied using lactosylceramide preparations having different fatty acid composition.     

Monoclonal antibody technology for mycotoxins

Specific monoclonal antibodies (MABs) against aflatoxins, ochratoxin A, zearalenone, diacetoxyscirpenol and T-2 toxin have been prepared in various laboratories by the application of hybridoma technology to mycotoxins. These antibodies can be selected for sensitivity, reduced cross-reactivity, reliability and ease of production. When a suitable antibody is chosen it can then be used in a rapid immunological method such as an enzyme-linked or radio-immunoassay or immunoaffinity chromatography system. These assays have a lower limit of mycotoxin detection in the ng/ml range and have been applied to the determination of mycotoxins in samples such as maize, peanuts, peanut butter, milk and porcine kidneys. Using these immunoassay techniques, sample preparation has generally been simplified to a matter of solvent extraction of mycotoxins from the sample followed by dilution; under these conditions, levels of 1-5ug of mycotoxins/kg of sample can be found. The application and advantages of MABs to mycotoxins and the use of these antibodies in various assay techniques is discussed.     

Site-specific antibody drug conjugates for cancer therapy

Antibody therapeutics have revolutionized the treatment of cancer over the past two decades. Antibodies that specifically bind tumor surface antigens can be effective therapeutics; however, many unmodified antibodies lack therapeutic activity. These antibodies can instead be applied successfully as guided missiles to deliver potent cytotoxic drugs in the form of antibody drug conjugates (ADCs). The success of ADCs is dependent on four factors—target antigen, antibody, linker, and payload. The field has made great progress in these areas, marked by the recent approval by the US Food and Drug Administration of two ADCs, brentuximab vedotin (Adcetris^®) and ado-trastuzumab emtansine (Kadcyla^®). However, the therapeutic window for many ADCs that are currently in pre-clinical or clinical development remains narrow and further improvements may be required to enhance the therapeutic potential of these ADCs. Production of ADCs is an area where improvement is needed because current methods yield heterogeneous mixtures that may include 0–8 drug species per antibody molecule. Site-specific conjugation has been recently shown to eliminate heterogeneity, improve conjugate stability, and increase the therapeutic window. Here, we review and describe various site-specific conjugation strategies that are currently used for the production of ADCs, including use of engineered cysteine residues, unnatural amino acids, and enzymatic conjugation through glycotransferases and transglutaminases. In addition, we also summarize differences among these methods and highlight critical considerations when building next-generation ADC therapeutics.     

Monoclonal antibody disulfide reduction during manufacturing

Manufacturing-induced disulfide reduction has recently been reported for monoclonal human immunoglobulin gamma (IgG) antibodies, a widely used modality in the biopharmaceutical industry. This effect has been tied to components of the intracellular thioredoxin reduction system that are released upon cell breakage. Here, we describe the effect of process parameters and intrinsic molecule properties on the extent of reduction. Material taken from cell cultures at the end of production displayed large variations in the extent of antibody reduction between different products, including no reduction, when subjected to the same reduction-promoting harvest conditions. Additionally, in a reconstituted model in which process variables could be isolated from product properties, we found that antibody reduction was dependent on the cell line (clone) and cell culture process. A bench-scale model using a thioredoxin/thioredoxin reductase regeneration system revealed that reduction susceptibility depended on not only antibody class but also light chain type; the model further demonstrates that the trend in reducibility was identical to DTT reduction sensitivity following the order IgG1λ > IgG1κ > IgG2λ > IgG2κ. Thus, both product attributes and process parameters contribute to the extent of antibody reduction during production.     

Monoclonal antibody successes in the clinic

Most monoclonal antibodies in clinical trials are owned by small biotech companies. But with blockbuster-sized revenues and approval rates higher than those for small-molecule drugs, that all may be set to change.     

Monoclonal antibody targeting of N-cadherin inhibits prostate cancer growth, metastasis and castration resistance

The transition from androgen-dependent to castration-resistant prostate cancer (CRPC) is a lethal event of uncertain molecular etiology. Comparing gene expression in isogenic androgen-dependent and CRPC xenografts, we found a reproducible increase in N-cadherin expression, which was also elevated in primary and metastatic tumors of individuals with CRPC. Ectopic expression of N-cadherin in nonmetastatic, androgen-dependent prostate cancer models caused castration resistance, invasion and metastasis. Monoclonal antibodies against the ectodomain of N-cadherin reduced proliferation, adhesion and invasion of prostate cancer cells in vitro. In vivo, these antibodies slowed the growth of multiple established CRPC xenografts, blocked local invasion and metastasis and, at higher doses, led to complete regression. N-cadherin-specific antibodies markedly delayed the time to emergence of castration resistance, markedly affected tumor histology and angiogenesis, and reduced both AKT serine-threonine kinase activity and serum interleukin-8 (IL-8) secretion. These data indicate that N-cadherin is a major cause of both prostate cancer metastasis and castration resistance. Therapeutic targeting of this factor with monoclonal antibodies may have considerable clinical benefit.     

Monoclonal antibody to dengue capsid protein

Dengue Fever (DF) and Dengue Hemorrhagic Fever/Dengue Shock Syndrome (DHF/DSS) are considered the most important arthropod-borne viral diseases in terms of morbidity and mortality. The emergency and severity of dengue (Den) infections increase the necessity of an early, quick and effective dengue laboratory diagnostic. Viral isolation is considered a gold standard for diagnosis dengue infection using monoclonal antibodies (mAbs) as a tool for determining serotype specificity. Alternatives have been used to improve sensitivity and time in dengue diagnosis. Based on the early expression of dengue C protein in the life cycle, we focused our study in the application of an anti-dengue 2 virus capsid protein mab in dengue diagnosis. The kinetic expression of dengue-2 capsid in mosquito cells and its immuno-localization in experimentally infected suckling albin Swiss (OF-1) mice brain tissues was established. The results demonstrate the utility of this mAb in significant early dengue diagnosis in traditional isolation. On the other hand, a preliminary study of an enzyme immunoassay method using 8H8 mab for specific detection of dengue C protein antigen was performed making possible recombinant C protein quantification. The results suggest that detection of dengue capsid protein could be useful in the diagnosis of early dengue infection.     

Monoclonal antibody engineering in plants.

Techniques for plant transformation have been developed to such an extent that a number of foreign genes are currently being introduced into transgenic plants. Tobacco plants that produce monoclonal antibodies are of interest, because in addition to synthesis of two gene products (i.e. the heavy and light chains), the two polypeptides need to be assembled correctly, in order to result in a functional antibody. The studies on a catalytic antibody suggest that this is the case, and that the antibody functions identically to the native murine-derived antibody. The only difference observed was in the glycosylation of the heavy chain. Further transgenic plants are being generated to produce monoclonal antibodies that may be used therapeutically (and are therefore required in large quantities), or to provide disease resistance in plants. In addition, the ability of plants to assemble antibody complexes is being investigated further, to study the possibility of generating secretory IgA, which consists of heavy and light chains as well as two additional polypeptide units.