Antibody aggregate removal with CEX solutions in frontal mode

How does frontal chromatography help purification?

As upstream titers continue to increase, traditional purification steps are under increasing pressure to advance. Aggregate removal using CEX bind-elute technologies is often a key constraint, with long processing times and loading limited to tens of grams per liter of resin and significant volumes of resin and buffers.

Frontal flow-through chromatography solutions like Eshmuno® CP-FT resin and Natrix® CH chromatography membrane are designed for efficient aggregate removal at high mass loading:

• Eshmuno® CP-FT resin enables aggregate removal in frontal chromatography mode, with typical loading of 1000 g/L and substantially lower resin and buffer requirements compared to traditional CEX bind-elute operations.
• Natrix® CH chromatography membrane provides single-use frontal-mode aggregate removal at high flow rates, typical loadings of 1000 g/L, and reduced buffer consumption compared to standard CEX resin workflows.

For manufacturers working with higher-titer or intensified mAb processes, CEX frontal chromatography options unlock purification potential, shorten processing time and lower resin or membrane and buffer requirements. Both the resin and membrane technologies offer operational flexibility with the option to run in bind elute mode if needed.

This technical article explains the benefits of each technology for different purification applications to help you select the right option for your process.

How does frontal chromatography achieve higher loading?

In traditional mAb downstream processing, CEX purification in bind-elute mode often follows Protein A capture and viral inactivation. At this stage, the polishing complexity depends heavily on the performance of the primary capture step, particularly aggregate and HCP levels. Aggregate removal can be difficult as mAb aggregates often have similar isoelectric points and hydrophobicity to mAb monomers. In addition, CEX operating conditions for one molecule may not be readily transferable to others, complicating process development and reducing platform flexibility.

These challenges become more pronounced with high-concentration mAbs and more complex molecules, including bispecific antibodies (BsAb), hydrophobic mAbs, and antibody drug conjugates (ADCs). As a result, traditional bind-elute chromatography often becomes a downstream bottleneck due to low productivity resulting from limited loading capacity.

Frontal chromatography mode offers a different approach for aggregate removal. Under strong binding conditions, typically pH 4.0 - 5.5 and low conductivity, mAb monomers and protein aggregates initially bind to the resin or membrane ligands. As loading increases, the aggregates preferentially bind to the media, displacing the monomer. Load conditions need to be optimized to maximize monomer recovery and minimize the levels of high molecular weight (HMW) impurities in the flow-through pool.

Eshmuno^® CP-FT resin and Natrix^® CH chromatography membrane are typically loaded at 1000 g/L, depending on the feed composition, aggregate level, and operating conditions. This higher loading significantly reduces media and buffer volumes compared to traditional bind-elute CEX approaches.

How Eshmuno^® CP-FT resin improves aggregate removal

Eshmuno^® CP-FT CEX resin was designed for frontal chromatography and achieves substantially higher loading than traditional bind-elute CEX chromatography. Figure 1 shows an example where Eshmuno^® CP-FT resin is loaded at 1000 g/L resin in frontal mode compared to 80 g/L load capacity with typical bind-elute technologies. For purification of 1 kg of mAb, this reduced the volume of resin from 12.5 L to 1 L based on 20 cm bed height columns. 

The smaller column volume results in a smaller footprint with lower buffer demands for column preparation and run steps: the Eshmuno^® CP-FT column required 15 L of buffer compared to 313 L for the bind-elute process. This lower buffer demand further streamlines operations and improves downstream economics.

In this same example, purification of the mAb with Eshmuno^® CP-FT resin resulted in more than 85% monomer recovery at 600 g/L loading, while aggregates were reduced from 7% in the feed to less than 1% in the flow-through pool at 1000 g/L loading. Although HCP removal was slightly lower following CEX purification in frontal chromatography rather than bind-elute steps, after AEX polishing the HCP levels in both the frontal and bind elute chromatography tests were below 10 ppm. For additional information, read the Eshmuno^® CP-FT resin data sheet.

Expanded aggregate removal with Natrix^® CH chromatography membrane

Natrix^® CH chromatography membrane devices, like Eshmuno^® CP-FT resin, use strong CEX chemistry to support aggregate removal in frontal chromatography mode. The membrane format enables much faster flow rates than traditional resin technologies. The combination of fast flow rate, high capacity, operational flexibility, and a plug-and-play device format makes Natrix^® CH devices well suited for intensified mAb processes requiring speed and flexibility. Extensive studies have demonstrated that Natrix^® CH devices effectively remove aggregates at higher loadings than other commercially available CEX membrane adsorbers.¹

The higher ionic density of Natrix^® CH membrane chromatography devices allows superior removal of mAb aggregates and HCP impurities as compared to two commercially available low-capacity CEX membrane adsorbers. When operating in frontal chromatography mode at pH 5 and a conductivity of 9 mS/cm, Natrix^® CH chromatography membranes achieve typical loading capacities of 1000 g/L with feed streams containing less than 4% aggregates (Figure 2A). When higher levels of aggregates are present, there is a tradeoff between loading and aggregate removal (Figure 2B). In both streams, Natrix^® CH chromatography membrane devices removed aggregates much more efficiently than other commercially available membrane adsorbers, especially at high load capacity. Natrix^® CH chromatography membrane devices also showed more effective host cell protein removal than other membrane adsorbers (data not shown). The result is high binding at flow rates 40x faster than resin and improved productivity (g/L/hr) up to 35x higher than CEX resin.

Superior binding performance was also demonstrated in bind-elute mode. Using the same mAb-1 fluid feed stream at pH 5, a conductivity of 9 mS/cm, and a flow rate of 10 MV/min, the dynamic binding capacity at 10% breakthrough (DBC_10%) of Natrix^® CH chromatography membrane devices was more than five times higher than other commercially available membrane adsorbers (Figure 3).

Another key benefit of Natrix^® CH devices is the plug-and-play device format. Unlike resin chromatography, the membrane device significantly simplifies operations by eliminating column packing, cleaning, and storage while reducing validation activities. These disposable devices can be used for up to 20 cycles with a single product batch without loss of performance; however, reuse across multiple product batches is not recommended. The single-use format can improve facility utilization with higher flexibility and reduced changeover time between batches.

Selecting the right frontal CEX chromatography technology

The choice between Eshmuno^® CP-FT resin or Natrix^® CH chromatography membrane devices depends on multiple process features and objectives, including process design, manufacturing setup, aggregate concentration and composition of the feed stream, processing time, batch size, and number of batches per year.

Both technologies support frontal chromatography for aggregate removal when the aggregate levels in the feed stream are less than 5%.

Both Natrix^® CH chromatography membrane devices and Eshmuno^® CP-FT resin support purification from the earliest stages of process development through commercial manufacturing.

Eshmuno^® CP-FT resin

• Well suited for biomanufacturers with traditional resin-based chromatography infrastructure, including continuous downstream operations. The column format may be preferred where established packing, scale-up, and resin handling workflows are already in place.
• The resin column format may be preferable for biomanufacturers processing large volumes of material in traditional batch or continuous downstream operations, particularly where resin-based scale-up is already established.
• For feed streams with higher aggregate concentrations, particularly above 5%, or dimer concentrations above 4%, Eshmuno^® CP-FT resin provides more effective aggregate removal.

Natrix^® CH chromatography membrane devices

• Well suited for intensified fed-batch operations or single-use facilities where high flow rates, low residence times, short processing times and simplified operations are priorities. The ready-to-use membrane format eliminates column packing, cleaning, and packing validation.
• Natrix^® CH chromatography membrane devices are especially relevant for biomanufacturers looking to move away from large chromatography columns towards single-use plug-and-play devices and/or smaller footprints.
• The single-use format is ideal for contract manufacturing operations (CMOs) and multiproduct facilities, reducing cleaning validation requirements, shortening changeover time, and minimizing footprint.

Extensive technical and applications expertise

We understand it can be challenging to find the right purification technology for your process needs. Whether you’re facing a new purification challenge or you're looking to second source a resin to maintain manufacturing continuity, we have options. Reach out to learn more.

Key takeaways

• Frontal flow-through CEX chromatography enables high loading and efficient aggregate removal while maintaining monomer recovery. Eshmuno^® CP-FT resin and Natrix^® CH membrane typically support loadings of around 1,000 g/L.
• Both technologies can support process development through commercial manufacturing and technology selection depends on the feed profile, scale, batch frequency, and process format.
• Eshmuno^® CP-FT resin is suited to resin-based processes with established column infrastructure, scale-up workflows, or higher aggregate and dimer levels—particularly feeds with >5% aggregates or >4% dimers.
• Natrix^® CH chromatography membrane supports faster, single-use processing for low-to-moderate aggregate feeds, with typical loading of 1,000 g/L for feeds containing <4% aggregates. 

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