Downstream processing monoclonal antibodies

The application of the SMB-technique to the downstream processing of biotechnological products requires some specific changes to meet the special demands of bioproduct isolation. Some exemplary applications are given including separations of sugars, proteins, monoclonal antibodies, ionic molecules and optical isomers and for desalting. 

Ascites production, however, suffers from a number of drawbacks. It is costly, and the product is contaminated by significant levels of various mouse proteins, rendering subsequent downstream processing more complex. As a result, monoclonal antibody production by standard animal cell culture techniques has become the method of choice for the production of pharmaceutical-grade monoclonal antibody preparations. 

The extraction and purification of proteins from organisms or biological tissue can be a laborious and expensive process, and often represents the principal reason why vaccines and other therapeutic agents reach costs that become unattainable for many. Downstream processing also can be a major obstacle with respect to cost for large-scale protein manufacturing in plants. However, purification from plant tissues, while still costly, is in general less expensive than purification from their mammalian and bacterial counterparts. Indeed, some plant-derived biopharmaceuticals, such as topically applied monoclonal antibodies, may require only partial purification and thus be even less intensive in terms of labor and cost. 

The aim of most technologies is to generate a population of cells each of which secretes a desired product into the medium. For this to occur the cells do not need to be actively dividing and, in fact, this is sometimes counterproductive. Cells can remain viable at high cell densities using perfusion systems (Chapter 3) and the product purified from the spent medium (Spier, 1988). Furthermore, the simpler the growth medium (i.e. the fewer protein factors required) then the easier is the downstream processing and this is one reason for the development of serum-free media especially for the culture of hybridoma cells used for monoclonal antibody production ( 5.8). 

Russell, D. A., (1999). Plant-based production of monoclonal antibodies From field to clinic. Proc. Antibody Prod. Downstream Process., San Diego, CA, 1999. 

Kundu, P. K., Prasad, N. S., and Datta, D. (1998). Monoclonal antibodies High density culture of hybridoma cells and downstream processing for IgG recovery. Indian J. Exp. Biol. 36, 125-135. 

Burton, S. 2002. A generic approach to the purification of monoclonal antibodies An alternative to protein A. IBC Conference Antibody Production Downstream Processing, Feb 13-15, San Diego, CA. 

There is no definitive answer as to the best system to use it depends upon the nature of the cell and the product, the quantity of product, downstream processing capability, licensing regulations, etc. However, a rough guide to relative costs for producing monoclonal antibodies by perfusion, continuous-flow and batch culture is the ratio 1 2 3 5. A summary of the capacity of the various systems is given in Table 5.1.2. 

After biological reactions have generated a product of interest, it is necessary to recover this product from a liquid mixture that typically contains several undesirable components. The treatment of any culture broth after bioreactor cultivation is known as downstream processing. Downstream processing can account for 60-80%) of the total production cost, particularly in the production of modern recombinant proteins and monoclonal antibodies. A typical downstream process requires several steps in the areas of solid-liquid separation, cell rupture, product recovery, and product purification. It is important to minimize the number of downstream processing steps required because significant product losses inevitably occur during each step.f ... 

H. J., A base-tolerant resin for Monoclonal Antibody purification. 3rd International Symposium on Downstream Processing of Genetically Engineered Antibodies and Related Molecules, 2004, Nice, France. 

It is clear that this difficult separation task cannot be done with a single chromatographic step. Therefore, the typical downstream process for example, a monoclonal antibody consists of three distinct chromatographic steps capturing -intermediate purification and polishing. 

His main research interests are in Chemical Reaction Engineering, with particular emphasis on polymer reactions and reaction-separation processes based on continuous chromatography. More recently, his interest in chromatographic separations has evolved in the area of biomolecules with specific focus on therapeutic proteins and monoclonal antibodies. The general aim of his research is the development of new concepts for the downstream processing of these materials. 

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