Protein A affinity chromatography is widely used as the capture step for monoclonal antibody and Fc fusion proteins. Host cell proteins (HCP) and residual DNA (rDNA) are the two major process-related impurities that can be significantly reduced through affinity chromatography. Extensive process development efforts have been focused on Protein A chromatography step to achieve maximum impurities reduction so as to relieve the burden in subsequent downstream purification steps. Here, we present a novel technique of using dextran sulfate as a treatment agent added to Protein A load material to effectively reduce HCP and rDNA in the capture chromatography step. The clearance of HCP and rDNA is achieved through a unique mechanism that is different from the one seen in typical pre-Protein A flocculation operation. Results also show that, for multiple monoclonal antibody and fusion protein products, adding dextran sulfate to Protein A load material can reduce the Protein A pool turbidity during subsequent pH adjustment, leading to simple filtration of the pH adjusted pool for polishing chromatography step. Experimental evidence suggesting the unique mechanism of dextran sulfate in achieving improved HCP and rDNA clearance will be discussed, with examples to show the importance of gaining the mechanistic understanding to the development of an effective Protein A chromatography step.

Mechanism and application of dextran sulfate in protein A affinity chromatography to achieve improved HCP and DNA clearance for biologics purification

253rd National Meeting (2017)

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