Biological drugs of the pre-biotechnology era

The development of proteins as therapeutics prior to the 1980s suffered from some major limitations. In some instances, concentration of the desired protein in the sonrce material was low, rendering its isolation and purification laborious and expensive. In other cases, the ability to produce sufficient quantities of some proteins was limited by the availability of starting material, resulting in insufficient production to meet the needs of the patient population. Aside from the quantitative limitations, the presence of infectious agents, mainly viruses, in the tissues and biological fluids of humans and animals posed the risk of infection to the patients. All protein drugs suffered from one or all of these drawbacks (Snape, 1991). 

The starting source materials used for the production of therapeutic proteins were heterogeneous mixtures obtained from several humans or animals, requiring the pooling of somce material from a large number of individuals to eliminate individual and batch to batch variation of post-translational modifications in the final product. Thus, starting plasma lots used in fractionation are made from pools of plasma derived from 10,000 to 12,000 individuals (Snape, 1991). 

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CH. 3] BIOLOGICAL DRUGS OF THE PRE-BIOTECHNOLOGY ERA 99 Secretion leader hGH cDNA... 

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