Influence of excipients in Protein A chromatography and virus inactivation

The purification of monoclonal antibodies and Fc fusion proteins consist of several unit operations operated commonly as a platform approach, starting with Protein A chromatography. The first capture step, the following low pH virus inactivation, and subsequent ion exchange chromatography steps are mostly able to remove any impurities, like host cell proteins, aggregates, and viruses. The changes in pH and conductivity during these steps can lead to additional unwanted product species like aggregates. In this study, excipients with stabilizing abilities, like polyols, were used as buffer system additives to study their impact on several aspects during Protein A chromatography, low pH virus inactivation, and cation exchange chromatography. The results show that excipients, like PEG4000, influence antibody elution behavior, as well as host-cell protein elution behavior in a pH-gradient setup. Sugar excipients, like Sucrose, stabilize the antibody during low pH virus inactivation. All excipients tested show no negative impact on virus inactivation and dynamic binding capacity in a subsequent cation exchange chromatography step. This study indicates that excipients and, possibly excipient combinations, can have a beneficial effect on purification without harming subsequent downstream processing steps.