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Eliminating the affinity chromatography step in the mAb purification process trims equipment requirements, shrinks the plant footprint - and reduces costs.
The market for therapeutic monoclonal antibodies (mAbs) has grown tremendously in the last decade, and it is estimated that mAbs and their derivatives account for almost 36% of the biopharmaccuticals under development, including vaccines and gene therapy (I). These and other therapeutic proteins arc produced at the industrial scale using various recombinant cell lines, such as bacteria (c¿>.. /·.. coli), yeast, and mammalian cells ? » .e" Chinese Hamster Ovary (CHO) cells (2)). with CHO cells being the most popular choice because they otter several benefits (3).
Biopharmaceutical products must have very high purity, with the concentration of host cell proteins and DNA reduced to the range of parts per million relative to the desired product, or lower. The final product must also be sterile (no viable micro-organisms present), and should contain less than IO ng of DNA per dose and less than one virus per million doses. This stringent purification of mAbs produced in CHO cells is typically accomplished using a three-column chromatography process (Figure 1 ) that consists of protein A affinity chromatography as an initial capture step, followed by cation exchange (CHX) and anion exchange (AEX) chromatography as polishing steps and a virus filtration (VF) step (3). The protein A ligand has a high affinity for one area of the mAb. specifically the cry stall izahle fragment (Fc). which enables the mAb's capture from the cell culture fluid (thus the terni affinity chromatography).
Even though these chromatography steps are able to meet the stringent purification requirements, they arc expensive, especially the protein A affinity step, which accounts for almost 35% of the total raw material costs for downstream purification (4). With growing demand for therapeutic mAbs and increasing market competition, significant attention is being focused on reducing manufacturing costs and improving process efficiency for industrialscale pnxluction. As a result, there has been much interest in the development of cost-effective non-affinity purification processes that do not involve protein A.
In one of the early studies on the purification of industrial-scale mAb feed streams using a non-affinity process (4). Fahrncr and I -Oilman integrated different chromatography steps into three-column non-affinity purification sequences...