How to select mAb chromatography resins and membranes

Section overview

• Start with the role of the chromatography step
• Key considerations for Protein A capture
• What to consider in intermediate purification & polishing
• Start by defining the purification challenge
• Look beyond binding capacity, yield and purity
• Find the right chromatography path for your process
• Related products

As upstream productivity increases and antibody formats become more complex, downstream purification is under growing pressure to keep pace and not become a bottleneck. Elevated titers increase the load for capture steps, while high levels of product-related impurities, aggregates, host cell proteins, DNA, and leached Protein A ligand can make polishing more difficult. The result is a familiar challenge for process development and MSAT teams: how to choose a purification train that maximizes productivity and provides the purification performance and process robustness at manufacturing scale.

Selecting the right purification technology depends on the molecule characteristics and process step. Before evaluating resins, chromatography membranes or other purification options, key molecule properties including molecular weight, isoelectric point (pI), charge profile and hydrophobicity should be understood.  These characteristics influence how the molecule interacts with the stationary phase and help determine which separation mechanisms are most appropriate.

In mAb capture and polishing, purification improves when sequential steps use different or orthogonal interactions. However, adding steps can reduce yield, increase process time and add costs. The ideal purification train meets product quality specifications in as few steps as possible. There are multiple reasons a drug manufacturer may need to select a new purification technology:

• Upstream process improvements: Higher titers can increase downstream load and turn legacy technologies into a bottleneck
• Molecule with separation challenges: Different antibody structure with charge variants, aggregates or other impurities that challenge standard purification trains
• Tech transfer: Creates the opportunity to re-evaluate resin or membrane options
• Supply security: Qualifying a second source chromatography resin to reduce supply risk
• Reduce costs: Newer technologies may offer higher loading capacity, improved separation, or greater stability which can support longer resin lifetime and lower processing costs.

This article outlines key considerations for selecting purification technologies for monoclonal antibody capture and polishing and provides a roadmap for evaluation to support efficient, scalable downstream processing.

Start with the role of the chromatography step

A resin should be evaluated in the context of the step it needs to perform. Capture, intermediate purification, and polishing steps solve different problems (Table 1).

While the steps above outline broad objectives and key selection considerations, the most appropriate purification strategy depends on the process: is it traditional or intensified processing, batch or continuous operation? The stage of development is also important – are you developing a small-scale process or looking to scale-up to manufacturing?

The ideal process balances purity, yield, and cost to achieve robust, scalable, purification. Because purification steps are sequential, decisions made for the capture step influence the purification and performance requirements for downstream polishing.  Similarly, choices made early in development may have implications for scalability, process robustness, cost and product quality as manufacturing scale increases. Understanding technical needs, longer term process objectives and budget or footprint constrains, shapes decisions on any purification platform. 

Key considerations for Protein A capture

For intensified mAb processes with higher titer mAbs, high DBC at short RT may be key to avoiding bottlenecks in the bind-elute capture step. Alternatively, you may consider multi-column capture as a way to improve productivity of this critical capture step. Multi-column capture systems are a fully automated, single-use solution for continuous closed capture chromatography. 

What to consider in intermediate purification & polishing

The complexity of the molecule drives selection of the chromatography resin or membrane for purification steps downstream of Protein A capture. The purification train for a traditional mAb typically includes a bind-elute cation exchange (CEX) intermediate purification step, followed by an anion exchange (AEX) polishing step, although the order of these steps may be reversed, dependent on the process.

Bind-elute CEX technologies provide selectivity for purification, but productivity is low, and these steps can quickly become a bottleneck. Newer CEX technologies operating in frontal flow-through mode offer higher loading capacities, shorter RT, excellent aggregate removal, and greater operational flexibility than conventional bind-elute resins, particularly for high titer intensified processes.

• Improve Productivity: Traditional bind-elute CEX technologies have lower loading capacity and longer RT than newer chromatography technologies that operate in frontal flow-through mode, which typically have loading capacities of more than 1000 g/L with short RT.
• Enhance Selectivity: Frontal flow-through CEX technologies efficiently remove aggregates even when levels are high.
• Expand Flexibility: Frontal flow-through CEX technologies are available as resins or in single-use membrane chromatography device formats that expand flexibility and eliminate multiple steps typical of resin chromatography including cleaning validation, column packing and storage.

Newer therapeutic modalities often contain closely related product- and process- impurities that cannot be easily resolved using a single separation mechanism. Mixed mode technologies that combine more than one binding mechanism in a single chromatography medium can help separate closely related species and streamline purification. Mixed-mode resins can:

• Enhance Selectivity: Mixed-mode chromatography resins that contain CEX and hydrophobic interaction chromatography (HIC) can efficiently separate closely related species in highly hydrophobic and structurally complex antibody formats.
• Streamline Purification: Mixed-mode chromatography resins enable efficient separation and purification in a single step and may eliminate the need for further polishing.
• Improve Yield: Fewer chromatography steps improve product yield.
• Reduce Costs and Save Time: Fewer steps save time and reduce resin and labor costs.

Start by defining the purification challenge

 Before selecting a purification technology, define the main challenge:

• Is the molecule sensitive to low pH, salt, or specific buffer conditions?
• Is the process being designed for conventional batch operation, intensified processing, or future continuous manufacturing?
• Is the priority high-capacity capture?
• Is impurity clearance (HCP, DNA, or leached Protein A ligand) the main challenge?
• Are product-related variants difficult to resolve?
• Is the resin being selected for supply security or to reduce costs?
• Are there footprint, flexibility or transferability factors to consider?

These questions help determine the scope and approach for process development and optimization. 

Look beyond binding capacity, yield and purity

Improving productivity (grams of product per unit volume of separation medium per unit time) is often a key driver of any effort to develop or improve a purification template. Higher binding capacity at short RT improves productivity but should be considered in the context of other important objectives. To expedite the process, most resin evaluations leverage high throughput robotic workflows with multivariate analysis and high throughput analytics to identify conditions that maximize binding capacity, yield and purity.  Other criteria may also be considered as selection narrows:

Dynamic binding capacity at relevant conditions

Capacity should be assessed at the residence time, bed height, feed concentration, and process conditions that reflect the intended application. This is especially important for intensified processes, where shorter residence times and higher loading may be needed.

Yield and product quality

The resin must support impurity clearance while maintaining acceptable yield and product quality. Harsh elution or cleaning conditions may affect sensitive molecules, so recovery should be evaluated together with product stability.

Purity

How effectively does the resin separate the target molecule from impurities? For polishing, selectivity may be more important than capacity, particularly when removing aggregates, fragments, charge variants, or closely related product impurities.

Cleaning and resin lifetime

Cleaning-in-place stability and lifetime performance influence cost of goods, bioburden control, and process robustness. For Protein A capture, resin lifetime can be a major economic factor because resin is a high-value raw material and will be used across many cycles.

Pressure-flow performance

Pressure-flow behavior affects productivity, scalability, and facility fit. Resins used in manufacturing should support the required flow rates and bed heights without creating excessive pressure or operational risk.

Operational costs

Resin or chromatography membrane costs are an important component of overall process economics. Operational costs should consider lifetime, costs for sanitization and regeneration and time associated with these efforts.

Technical support

A resin used in development should have a clear path to manufacturing scale. Consider packing behavior, column compatibility, supply reliability, and technical support available for scale-up or tech transfer.

Regulatory and documentation support

Supporting documentation becomes increasingly important for resins used at larger scale processes. Consider the availability of quality, regulatory, and risk assessment documentation needed to support process qualification and later-stage filings.

Find the right chromatography path for your process

As mAb processing evolves, molecule complexity increases and newer chromatography technologies become available, finding the right resin for any process is becoming increasingly important to both purification operations and process economics. 

A structured approach can make resin selection more practical:

• Define the role of the chromatography step. The main purification challenge should guide the choice of chromatography technology. Prioritize what matters most: flexibility, productivity, purity, impurity clearance, robustness, scale-up readiness, cost, or supply security.
• Understand the molecule and impurity profile. Resin and technology selection should start with the molecule, process and manufacturing context; mAb format, process mode, facility constraints, titer, and impurity profile all influence the best capture and polishing approach.
• Evaluate capacity, selectivity, recovery, pressure-flow behavior, and cleaning stability. Dynamic binding capacity is important, but not sufficient on its own. Evaluate it alongside recovery, pressure-flow performance, cleaning stability, resin lifetime, operating conditions, and overall process fit.
• Consider bind-elute and flow-through options early. Flow-through frontal chromatography can help relieve CEX bottlenecks. Frontal chromatography supports process intensification by enabling higher loading capacity and efficient aggregate removal without a bind-elute step.
• Plan for scale-up, documentation, and manufacturing robustness. Comprehensive documentation packages provide transparency, accelerate risk-based decisions, streamline implementation and improve regulatory readiness.

The right resin should do more than perform in a screening experiment. It should support an efficient, scalable, and robust downstream process from development through manufacturing.

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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 are looking to second source a resin to maintain manufacturing continuity, we have options.

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