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Animal Biotechnology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
MABs are used for either the treatment of or protection from a disease. Antibodies specific to a cell type, for example, tumor cells, can be linked with a toxin polypeptide to yield a conjugate molecule called an immunotoxin. The antibody component of the immunotoxin will ensure that it is bound specifically and only to the target cells, and the attached toxin will kill such cells. Immunotoxins having ricin have been prepared and evaluated for killing of tumor cells with considerable success. Ricin is a natural toxin found in the endosperm of castor (Ricinus communis). It has two polypeptides called A (toxin peptide) and B (a cell-binding polypeptide, lectin). Ricin A polypeptide enzymatically and irreversibly modifies the larger subunit of ribosomes (in fact, their EF2 binding site) making them incapable of protein synthesis. This toxin is effective against both dividing and nondividing cells as it inhibits protein synthesis.
Animal biotechnology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2018
The MABs are used for either the treatment of or protection from a disease. Antibodies specific to a cell type, for example, tumor cells, can be linked with a toxin polypeptide to yield a conjugate molecule called immunotoxin. The antibody component of immunotoxin will ensure that it is bound specifically and only to the target cells, and the attached toxin will kill such cells Immunotoxins, having ricin, have been prepared and evaluated for killing of tumor cells with considerable success. Ricin is a natural toxin found in the endosperm of castor (Ricinus communis). It has two polypeptides called A (toxin peptide) and B (a cell-binding polypeptide, lectin). Ricin A polypeptide enzymatically and irreversibly modifies the larger subunit of ribosomes (in fact, their EF2 binding site) making them incapable of protein synthesis. This toxin is effective against both dividing and nondividing cells as it inhibits protein synthesis.
Aptamers and Cancer Nanotechnology
Published in Mansoor M. Amiji, Nanotechnology for Cancer Therapy, 2006
Omid C. Farokhzad, Sangyong Jon, Robert Langer
The feasibility of using antibodies for targeted therapy, particularly for oncologic diseases, has been demonstrated repeatedly in the literature. Rituximab (Rituxan™) was the first therapeutic based on monocloncal antibodies to receive FDA approval in 1997 for treating patients with relapsed or refractory low-grade or follicular, CD20 positive, B-cell non-Hodgkin’s lymphoma.27 A wide variety of antibody-based drugs are now under clinical development or are in clinical practice today. For example, denileukin diftitox (Ontak™) is an FDA-approved immunotoxin for the treatment of cutaneous T-cell lymphoma.28 Many other radioimmunoconjugates or chemoimmunoconjugates directed against cell surface antigens are currently in various stages of clinical and pre-clinical development. Despite the recent success of monoclonal antibodies as targeting moieties, the use of antibodies for drug targeting may have a number of potential disadvantages. First, antibodies are large molecules (~ 20 nm for intact antibodies)29,30 and their use in developing nanoscale therapeutic and diagnostic tools may result in an increase in vehicle size without added advantage. Second, antibodies may be immunogenic. Despite the current engineering approaches to yield improved humanized antibodies, this problem is not universally solved. Third, the biological development of monoclonal antibodies can be difficult and unpredictable. For example, the target antigen may not be well tolerated by the animal used to produce the antibodies, or the target molecules may be inherently less immunogenic, making it difficult to raise antibodies against such targets (although, this problem is overcome with the use of phage display libraries).31,32 Fourth, the production of antibodies involves a biological process that can result in batch-to-batch variability in their performance, particularly when production is scaled up. The ideal targeting molecule for the delivery of nanoscale therapeutic and diagnostic systems should, like monoclonal antibodies, bind with high affinity and specificity to a target antigen but overcome or ameliorate some of the problems associated with the use and production of monoclonal antibodies.
Cloning, expression and characterization of a HER2-alpha luffin fusion protein in Escherichia coli
Published in Preparative Biochemistry and Biotechnology, 2019
Farzaneh Barkhordari, Nooshin Sohrabi, Fatemeh Davami, Fereidoun Mahboudi, Yeganeh Talebkhan Garoosi
Immunotoxins are recombinant proteins including a toxin molecule which will be fused to an antibody, hormone or cytokine through genetic engineering or chemical conjugation.[12] At present, the only FDA approved immunotoxin is denileukin diftitox, in which interleukin 2 (IL-2) has been conjugated to the bacterial diphtheria toxin[13,14] and is used for the treatment of recurrent cutaneous T-cell lymphoma.[15] The antibody fragments used in developing immunotoxins are usually the Fv part of antibodies specific for an antigen on the surface of the tumor or infected cells.[16] Single-chain Fv (scFv) molecules with molecular weight of 26–28 kDa, consist of variable regions of heavy and light chains of their corresponding whole antibodies.