Innovative next-generation monoclonal antibody purification using activated carbon: A challenge for flow-through and column-free processes

Abstract

Activated carbon (AC) is a porous solid with a larger surface area and lower cost than chromatography resins. AC has been used in the field of biopharmaceutical manufacturing for plasma-derived products and recombinant monoclonal antibodies (mAb). In our previous study, AC was employed in the purification process of therapeutic mAb as a replacement for Protein A affinity chromatography (PrA). In addition, we designed an all flow-through purification process using AC. In these investigations, greater effective clearance of high-molecular-weight species (HMW), low-molecular-weight species (LMW), host cell proteins (HCP), and DNA was observed compared to that of the conventional Protein A platform purification process. However, it was revealed that mAb recovery from the AC step was lower than that from the PrA step. In this work, to improve mAb recovery from the AC step while maintaining the effective removal of impurities, a pretreatment procedure conducted prior to the AC treatment was investigated. We found that both an ultrafiltration/dilution and reduction in the conductivity of the filtered cell culture supernatant after acid precipitation could improve both the impurity clearance and mAb recovery from the AC treatment. From the obtained results, we designed a two-step purification process in which AC treatment is followed by either cation exchange column chromatography or anion exchange column chromatography, and we compared this against the Protein A platform purification process. Excellent impurity clearance was achieved, even in the one-column process. Furthermore, we designed an innovative column-free flow-through purification process based on acid precipitation, clarification, ultrafiltration/dilution, and the implementation of an AC filter membrane and an anion exchange chromatography membrane. With this process in the pilot-scale, HCP level can be reduced to below 10 ng/mg, and HMW and LMW can be removed to below 1% while improving mAb recovery. From these results, it is strongly expected that AC is a promising candidate for the next generation of mAb purification processes to improve the economy and efficiency of the process.

Keywords: Bioprocessing; Cost reduction; Downstream; Protein separation; Therapeutic monoclonal antibody purification.