Bispecific Antibodies: production and use - Essay Example

? Bispecific Antibodies: production and use Bispecific Antibodies: production and use Introduction Bispecific antibody is an artificial protein comprising fragments of two distinct monoclonal antibodies, and subsequently binds to two dissimilar kinds of antigen. This antibody if widely applied in cancer immunotherapy, where bispecific antibody is engineered to bind simultaneously to a cytotoxic cell (CD3) and tumor cell (target) (AL-RUBEAI, 2011). Bispecific antibodies widen a potential utility of therapies based on antibodies through enabling engagement of two different targets simultaneously. However, production and design of bispecific antibodies have remained challenging. This is due to the need to slot in two different light and heavy chain pairs, while keeping and maintaining the architecture of the natural non-immunogenic antibody. Scientists present a production strategy for bispecific antibody that depends on co-culture of two bacterial strains. Each of these bacterial strains expresses a half antibody. Through this kind of approach, scientists assert that 28 distinctive bispecific antibodies can be produced (AL-RUBEAI, 2011). A bispecific antibody put against EGFR and MET (receptor tyrosine) mono-valently binds the targets, suppresses EGFR and MET driven tumor and cell growth, as well as inhibits their signaling. Such production strategy enables rapid bispecific antibody generation from any two antibodies in existence and yields varying quantities of bispecific antibodies adequate for a broad range of preclinical and discovery applications (FLICKINGER, 2013). Bispecific antibody is widely acknowledged and recognized as therapeutic molecules. This is due to the four approvals outside the United States and 23 approvals in the United States and other countries. The success of therapy and commercial resulting from bispecific antibodies inspires antibody producers and engineers to enhance the effectiveness of bispecific molecules. Subsequently, a new wave of antibodies is being evaluated in clinics, expecting various approvals. Such antibodies have been engineered with Fc leading to higher effector roles such as cytoxicity depending on complement and cell mediated cytoxicity depending on antibody (PAUL, 2008). Additionally, studies on various classes of bispecific antibodies, antibody therapeutics has led to remarkable clinical results, and the first bispecific antibody catumaxomab approval. For example a T cell retargeting agent approved in April 2009 in the European Union. Studies have also focused on recent clinical study and advances results about bispecific antibodies. Such studies are geared towards producing a new class of molecules to outshine bispecific antibodies as cancer immune therapy in the future. Bispecific antibodies possess a higher potential of cytotoxic. The antibodies bind to antigens that are weakly expressed. T-lymphocytes are not activated by cancer immunotherapy with bispecific antibodies because they do not have Fc receptors. This means the Fc region is not able to bind to them, while the Fab regions are used for tumor cells binding (PAUL, 2008). The production and design of bispecific antibodies is not easy. Production of bispecific antibodies has remained a challenge to most molecule engineers (ALFERMANN & VERPOORTE, 2000). This is because of the need to integrate two different light and heavy chain pairs, and at the same time keep and maintain the architecture of the natural non-immunogenic antibody. Today, bispecific antibody is acknowledged and recognized as therapeutic molecules. This is because of the worldwide approvals: four approvals outside the United States and 23 approvals in the United States and other countries. Engineers of bispecific antibodies and bispecific antibody producers have been inspired by the success of therapy and commercial that result from bispecific antibodies to continually enhance and promote the effectiveness of bispecific molecules (FLICKINGER, 2013). This paper seeks to discuss bispecific antibodies, their production, and use. Production of bispecific antibodies Production of bispecific antibodies stirs argument among research scientists. Several scientists have come up with different production mechanisms of bispecific antibodies. The most commonly used bispecific antibody production mechanism is the production strategy that depends on co-culture of two bacterial strains. Each of these bacterial strains expresses a half antibody. Through this type of approach, scientists argue that 28 distinctive bispecific antibodies can be produced. Production of bispecific antibodies requires generation of purified fragments of Fab x Fab of every antibody. The production uses reagents that are able to react with the thiols freely generated on lessening of disulfide interheavy chain of the fragments of Fab x Fab (LO, 2004). Upon reduction of interheavy disulfide chain, the Fabs that are produced are recombined to make up Fab x Fab BsAb. 5, 5’-dithiobis DTNB (2-nitrobenzoic acid) works to recreate disulfide bonds in between the Fabs. However, o-phenylenedimaleimide (o-PDM) functions to regenerate a thioether bond in between the Fabs. At the end of coupling, the bispecific antibodies are purified from Fabs that are not coupled through size-exclusion chromatography. At the end of the entire process, we get pure bispecific antibodies. The use of advanced bispecific antibody production has seen the recombinant formats validated and designed to some extent. These new formats include diabodies, tandem scFv, dual variable domain antibodies, tandem diabodies, and heterodimerization with the use of motif such as the Dock and Lock motif or CH1/Ck domain. The development of a single antibody domain from VH domain or Camelid antibody should be able to facilitate the improved antibody therapeutic design (ALFERMANN & VERPOORTE, 2000). In the past 25 years, DNA and monoclonal antibody technologies helped with the generation and production of antibody molecules not occurring normally in nature. The first generation bispecific antibody resembled normal molecules of immunoglobin; however, they had two binding arms equipped with different specialty bindings. Bispecific antibodies were constructed for engagement in cancer cells with immune cytotoxic cells. However, clinical trials for the same have remained insufficient for future development (VAN, SHAPIRO & ANNE?, 2001). Further production progress in the bispecific antibody development was due to the reduction of antibodies to their smallest binding domains. Due to the fact that these are bipartite with different genes producing variable fragments, there was an introduction of linker sequence so as to align the variable domains on one chain of polypeptide. This results into a one chain antibody. This allowed a combination with more linker sequence of two one chain antibodies of varying tandem specificity binding, in such a way that four products of gene are aligned ultimately on a single chain of polypeptide of about 55kDa. Pioneering study by Kufer indicated that target antigen-bispecific antibodies of this design had a potency of an exceptional quantity. The same could engage T cells for redirected lysis of cancerous cells at a very low ration of effector to target (ALFERMANN & VERPOORTE, 2000). Use of bispecific antibodies for cancer therapy There are extensive uses of bispecific antibodies in cancer therapy. There are many distinct applications of bispecific antibodies. Their cancer therapy potential is very promising. This is because of their ability to retarget cells or molecules of effectors to a target structure that is related to a given disease. There are many formats developed in the past few years. The commonly used formats are the tandem scFv and the bispecific diabody (VAN, SHAPIRO & ANNE?, 2001). With the continuous research studies, evidence shows that T cells have the ability to control the growth of tumor and survival among patients with cancer. This is possible in both early state and late stage of the disease. However, it is not easy to mount and sustain tumor specific T cell responses in patients with cancer. The tumor specific T cells are also limited by several mechanisms of immune escape tumor cells that are chosen in the process of immuniediting. There is an alternative approach of engaging T cells for cancer therapy: bispecific antibodies which are specific to target surface antigen on cancerous cells. Bispecific antibodies are capable of linking cancer cell with any type of cytotoxic T cell, independent of co stimulation, T cell receptor specificity, or presentation of peptide antigen. Recent study results from clinical research show that bispecific antibodies are therapeutic paradigm showing valid promise for treating of animal residual disease and cancer patients (VAN, SHAPIRO & ANNE?, 2001). Bispecific antibodies are gifted with superb specialties. Bispecific antibodies raise hopes for cancer therapy development, especially as treatment to cancer patients. However, extensive optimization via antibody production is required before effective molecules of IgG can be produced. Several bispecific antibodies have been approved for therapeutic cancer treatments in the United States and other nations. However, single agents of IgG molecules are not able to cure cancer (LO, 2004). Numerous outcomes of clinical trials and animal studies have outlined major discrepancies in their modes of function including effects of microenvironment, redundancy of pathways of molecules that lead to survival of cancer cells, suboptimal interaction with cell effectors because of alternative Fc receptor polymorphism or Fc glycosylation, competition with circulating IgG, and activation of receptors that are inhibitory. The challenges of bispecific antibodies can be tackled through producing bispecific antibodies with the ability to bind simultaneously to two distinct targets. Such molecules are able to retarget huge variety of payloads to cancerous cells. This potential has been highlighted in numerous research studies in the past years. However, the challenge in engineering and producing huge amounts of homogenous bispecific antibodies through the techniques available such as chemical cross linking or hybrid hybridomas obstructed the broader development and adoption of this approach (LO, 2004). Analysis of bispecific antibody Bispecific antibody is an artificial protein comprising fragments of two distinct monoclonal antibodies, and subsequently binds to two dissimilar kinds of antigen. As opposed to the conventional monoclonal antibodies, a pure bispecific antibody produced from this process is able to bind two different antigens simultaneously. Due to this advantage, bispecific antibodies are designed mostly for redirection of immune effector cell to tumors and for pre-targeting radionuclide to tumors. The antibodies bind to antigens that are weakly expressed. This antibody if widely applied in cancer immunotherapy, where bispecific antibody is engineered to bind simultaneously to a cytotoxic cell (CD3) and tumor cell (target) (WINK, 2006). T-lymphocytes are not activated by cancer immunotherapy with bispecific antibodies because they do not have Fc receptors. This means the Fc region is not able to bind to them, while the Fab regions are used for tumor cells binding. It is important to note that the first generation bispecific antibodies were engineered and produced by technologies of cell fusion or cross linking chemical technologies. After numerous studies, the use and application of genetic production technologies and engineering led to t eh rise of several formats of fragments of bispecific antibodies and entire molecules of IgG. Bispecific attract huge interest because of their ability to enable strategies of therapy that are not practically possible with other conventional monoclonal antibodies. Numerous formats of bispecific antibodies have shown clinical effectiveness among cancer patients. Bispecific antibodies catalyze efforts to have imaginative concepts of bispecific antibody translated into effective therapeutics. This is why the production of bispecific antibodies has brought about argument among research scientists, with s several scientists coming up with different production mechanisms of bispecific antibodies (WINK, 2006). Conclusion In conclusion, bispecific antibodies contributes to future cancer immunotherapy through redirecting several number of T cell clones existing in patients while abandoning majority of the immune escape means that nonetheless limit responses of specific antitumor of the clones of the T cells. Studies have focused on recent clinical study and advances results about bispecific antibodies. Such studies are geared towards producing a new class of molecules to outshine bispecific antibodies as cancer immune therapy in the future. Bispecific antibodies possess a higher potential of cytotoxic. The antibodies bind to antigens that are weakly expressed (GU, 2008). T-lymphocytes are not activated by cancer immunotherapy with bispecific antibodies because they do not have Fc receptors. This means the Fc region is not able to bind to them, while the Fab regions are used for tumor cells binding. More research studies and investigation are required to find out the contribution of the responses of tumor specific T cell and impact of T cells on clinical activity, broader utility of bispecific antibodies, and possible means of evading bispecific antibodies engaged T cells for malignant disease, cancer treatment (KONTERMANN, 2011). There is also a high possibility of actually treating cancer patients using bispecific antibodies. Other studies also focus on whether such antibodies prolong the overall cancer patient survival. Production of bispecific antibodies has led to various arguments among research scientists. Several studies suggest different production mechanisms of bispecific antibodies. The use of advanced bispecific antibody production has seen the recombinant formats validated and designed to some extent. These new formats include diabodies, tandem scFv, dual variable domain antibodies, tandem diabodies, and heterodimerization with the use of motif such as the Dock and Lock motif or CH1/Ck domain. The development of a single antibody domain from VH domain or Camelid antibody should be able to facilitate the improved antibody therapeutic design. Due to these developments in antibody production and engineering, it might be inferred that we are witnessing a turning point in bispecific antibody discipline, and most importantly the field of cancer immunotherapy (GU, 2008). List of References ALFERMANN, A. W., & VERPOORTE, R. (2000). Metabolic engineering of plant secondary metabolism. Dordrecht [u.a.], Kluwer Academic Publishers. AL-RUBEAI, M. (2011). Antibody expression and production. Dordrecht [etc.], Springer FLICKINGER, M. C. (2013). Upstream industrial biotechnology. http://search.ebscohost.com/login.aspx?direct=true&scope=site&db=nlebk&db=nlabk&AN=612608. GU, Y. (2008). Bispecific antibody targeted stem cell therapy for myocardial repair. Dissertation Abstracts International. 69-12. Thesis (Ph.D.)--University of California, San Francisco with the University of California, Berkeley, 2008. KONTERMANN, R. (2011). Bispecific Antibodies. Berlin, Springer Berlin. LO, B. K. C. (2004). Antibody engineering methods and protocols. Totowa, N.J., Humana Press. http://site.ebrary.com/id/10181521. PAUL, W. E. (2008). Fundamental immunology. Philadelphia, Wolters Kluwer/Lippincott Williams & Wilkins. VAN BROEKHOVEN, A., SHAPIRO, F., & ANNE?, J. (2001). Novel frontiers in the production of compounds for biomedical use. Dordrecht, Kluwer Academic Pub. http://www.myilibrary.com?id=4347. WINK, M. (2006). An introduction to molecular biotechnology: from molecular biological fundamentals to methods and applications in modern biotechnology. Weinheim, WILEY-VCH. Read More