Viral clearance using traditional, well-understood unit operations: session 1.2. Anion exchange chromatography; and session 1.3. Protein a chromatography

Viral clearance capability of monoclonal antibody purification

Viral clearance steps are routinely included in monoclonal antibody purification processes to safeguard product from potential virus contamination. These steps are often experimentally studied using product-specific feeds and parameters for each project to demonstrate viral clearance capability. However, published evidence suggests that viral clearance capability of many of these steps are not significantly impacted by variations in feed material or process parameter within commonly used ranges. The current investigation confirms robust retrovirus inactivation by low pH treatment and parvovirus removal by second-generation virus filters, independent to individual antibody molecules. Our results also reveal robust retrovirus removal by flowthrough anion exchange chromatography, inside the limits of protein load and host cell protein content. The cumulative viral clearance capability from these steps leads to an excess clearance safety factor of 10,000-fold for endogenous retrovirus-like particles. These results further justify the use of prior knowledge-based modular viral clearance estimation as opposed to repetitive experimentation.

On-column virus inactivation by solvent/detergent treatment for a recombinant biological product

Each process step in the manufacture of biological products requires expensive resources and reduces total process productivity. Since downstream processing of biologicals is the main cost driver, process intensification is a persistent topic during the entire product life cycle. We present here one approach for the intensification of bioprocesses by applying on-column virus inactivation using solvent/detergent (S/D) treatment during ion-exchange chromatography. The established purification process of a recombinant protein was used as a model to compare key process parameters (i.e., product yield, specific activity, impurity clearance) of the novel approach to the standard process protocol. Additional wash and incubation steps with and without S/D-containing buffers were introduced to ensure sufficient contact time to effectively eliminate enveloped viruses and to significantly decrease the amount of S/D reagents. Comparison of key process parameters demonstrated equivalent process performance. To assess the viral clearance capacity of the novel approach, XMuLV was spiked as model virus to the chromatographic load and all resulting fractions were analyzed by TCID50 and RT-qPCR. Data indicates the inactivation capability of on-column virus inactivation even at 10% of the nominal S/D concentration, although the mechanism of viral clearance needs further investigation.

Viral removal by column chromatography in downstream processing of monoclonal antibodies

For monoclonal antibodies (mAbs) produced in mammalian cells, viral safety is a critical concern. The downstream process, in addition to removing other impurities, needs to ensure robust clearance (removal or inactivation) of potential endogenous and adventitious viruses. In general, Protein A and polishing chromatography steps all can provide certain level of virus removal. Chromatographic removal combined with virus inactivation and nanofiltration usually provides adequate virus clearance across the overall downstream process. This article reviews the virus clearance capability of commonly used column chromatography, with attention to possible interference of virus-mAb interaction on virus removal. In addition, the potential of using viral surrogate as a safe alternative to live virus for assessing viral clearance is briefly discussed.

The prevention of an anomalous chromatographic behavior and the resulting successful removal of viruses from monoclonal antibody with an asymmetric charge distribution by using a membrane adsorber in highly efficient, anion-exchange chromatography in flow-through mode

Anion exchange (AEX) chromatography in the flow-through mode is a widely employed purification process for removal of process/product-related impurities and exogenous/endogenous viruses from monoclonal antibodies (mAbs). The pH of the mobile phase for AEX chromatography is typically set at half a unit below the isoelectric point (pI) of each mAb (i.e., pI - 0.5) or lower and, in combination with a low ionic strength, these conditions are usually satisfactory for both the recovery of the mAb and removal of impurities. However, we have recently encountered a tight binding of mAb1 to AEX resins under these standard chromatographic conditions. This anomalous adsorption behavior appears to be an effect of the asymmetric charge distribution on the surface of the mAb1. We found that mAb1 did not bind to the AEX resins if the mobile phase has a much lower pH and higher ionic strength, but those conditions would not allow adequate virus removal. We predicted that the use of membrane adsorbers might provide effective mAb1 purification, since the supporting matrix has a network structure that would be less susceptible to interactions with the asymmetric charge distribution on the protein surface. We tested the Natriflo HD-Q AEX membrane adsorber under standard chromatographic conditions and found that mAb1 flowed through the membrane adsorber, resulting in successful separation from murine leukemia virus. This AEX membrane adsorber is expected to be useful for process development because mAbs can be purified under similar standard chromatographic conditions regardless of their charge distributions.

Downstream Processing Technologies/Capturing and Final Purification : Opportunities for Innovation, Change, and Improvement. A Review of Downstream Processing Developments in Protein Purification

Increased pressure on upstream processes to maximize productivity has been crowned with great success, although at the cost of shifting the bottleneck to purification. As drivers were economical, focus is on now on debottlenecking downstream processes as the main drivers of high manufacturing cost. Devising a holistically efficient and economical process remains a key challenge. Traditional and emerging protein purification strategies with particular emphasis on methodologies implemented for the production of recombinant proteins of biopharmaceutical importance are reviewed. The breadth of innovation is addressed, as well as the challenges the industry faces today, with an eye to remaining impartial, fair, and balanced. In addition, the scope encompasses both chromatographic and non-chromatographic separations directed at the purification of proteins, with a strong emphasis on antibodies. Complete solutions such as integrated USP/DSP strategies (i.e., continuous processing) are discussed as well as gains in data quantity and quality arising from automation and high-throughput screening (HTS). Best practices and advantages through design of experiments (DOE) to access a complex design space such as multi-modal chromatography are reviewed with an outlook on potential future trends. A discussion of single-use technology, its impact and opportunities for further growth, and the exciting developments in modeling and simulation of DSP rounds out the overview. Lastly, emerging trends such as 3D printing and nanotechnology are covered. Graphical Abstract Workflow of high-throughput screening, design of experiments, and high-throughput analytics to understand design space and design space boundaries quickly. (Reproduced with permission from Gregory Barker, Process Development, Bristol-Myers Squibb).