The removal of host cell proteins (HCPs) in the manufacturing of mAbs remains a challenge. This article, from Issue 13 of the Analytix Reporter, teaches you how to improve depletion of difficult-to-remove lower molecular weight and hydrophobic HCPs and get a high mAb yield by adding a Carboxen® synthetic carbon polishing step in your monoclonal antibody production workflow.
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Introduction
Monoclonal antibodies (mAbs) are a class of critical biotherapeutic drugs. The demand for mAbs is steadily increasing. But the depletion of host cell proteins (HCP) in the manufacturing of mAbs remains a challenge. HCPs can represent an immune response risk after the administration of mAbs if not reduced to appropriate levels. Removal of HCPs is typically done via a Protein A (PA) chromatography capture step, carried out in bind- and-elute mode. Following the Protein A purification step, the feed is passed through two polishing steps in the form of ion exchangers (IEX), namely cation exchange chromatography (CEX) and anion exchange chromatography (AEX). The remaining impurities are mostly low molecular weight, hydrophobic HCPs, that are difficult to remove either because of their physiochemical properties, or their non-specific association with the antibody. These impurities represent the group of critical HCPs that need to be addressed in order to achieve the highest possible purification.
Efforts to further reduce HCP content beyond that achieved with the standard PA-IEX downstream processes are being considered One such solution is to add additional polishing steps, such as hydrophobic interaction chromatography (HIC) between the PA and IEX chromatographic steps. In this work, a post-Protein A (PPA) pool was applied to three different carbon-based adsorbents in flow-through mode to test their HCP depletion behaviour under dynamic conditions.
For methods, materials, experimental procedure, results and discussion, refer to the full article.
Conclusion
The Carboxen® synthetic carbons demonstrated excellent host cell protein reduction and high mAb yield. Carboxen® 1032 had the best performance among the three materials tested and showed a very good depletion of host cell proteins. At an HCP breakthrough of 10%, 2300 grams of monoclonal antibody per liter of adsorbent could be applied on Carboxen® 1032 and 14 grams of HCP per liter of adsorbent could be depleted. With the addition of a Carboxen® synthetic carbon polishing step to the standard PA-IEX downstream processes, difficult-to-remove lower molecular weight and hydrophobic HCPs can be depleted. With an added synthetic carbon purification step, downstream ion exchangers would bear a lower burden because of the reduction in impurities, so their durability can be increased. Ideally, the implemented step can replace one of the downstream ion exchangers. These points would lead to a reduction in production costs. In an alternative configuration, the Carboxen® synthetic carbon can act as a final polishing step to target the critical HCPs that are not removed in the standard PA-IEX process. Carboxen® synthetic carbons can ultimately lead to the production of a safer mAb product for the patient.
