Evaluation and comparison of alternatives to Protein A chromatography Mimetic and hydrophobic charge induction chromatographic stationary phases

Development of novel small peptide ligands for antibody purification

Small peptide ligands which were designed based on the interactions with human immunoglobulin G (IgG) using the molecular simulations, can offer a potential alternative for mAb purification with elution condition at pH 9 and pH 3.

Trends in Upstream and Downstream Process Development for Antibody Manufacturing

A steady increase of product titers and the corresponding change in impurity composition represent a challenge for development and optimization of antibody production processes. Additionally, increasing demands on product quality result in higher complexity of processes and analytics, thereby increasing the costs for product work-up. Concentration and composition of impurities are critical for efficient process development. These impurities can show significant variations, which primarily depend on culture conditions. They have a major impact on the work-up strategy and costs. The resulting "bottleneck" in downstream processing requires new optimization, technology and development approaches. These include the optimization and adaptation of existing unit operations respective to the new separation task, the assessment of alternative separation technologies and the search for new methods in process development. This review presents an overview of existing methods for process optimization and integration and indicates new approaches for future developments.

Maximizing binding capacity for protein A chromatography

Advances in cell culture expression levels in the last two decades have resulted in monoclonal antibody titers of ≥10 g/L to be purified downstream. A high capacity capture step is crucial to prevent purification from being the bottleneck in the manufacturing process. Despite its high cost and other disadvantages, Protein A chromatography still remains the optimal choice for antibody capture due to the excellent selectivity provided by this step. A dual flow loading strategy was used in conjunction with a new generation high capacity Protein A resin to maximize binding capacity without significantly increasing processing time. Optimum conditions were established using a simple empirical Design of Experiment (DOE) based model and verified with a wide panel of antibodies. Dynamic binding capacities of >65 g/L could be achieved under these new conditions, significantly higher by more than one and half times the values that have been typically achieved with Protein A in the past. Furthermore, comparable process performance and product quality was demonstrated for the Protein A step at the increased loading.

Evaluation of high-capacity cation exchange chromatography for direct capture of monoclonal antibodies from high-titer cell culture processes

Advances in molecular biology and cell culture technology have led to monoclonal antibody titers in excess of 10 g/L. Such an increase can pose concern to traditional antibody purification processes due to limitations in column hardware and binding capacity of Protein A resins. Recent development of high capacity cation exchangers can make cation exchange chromatography (CEX) a promising and economic alternative to Protein A capture. This work investigates the feasibility of using CEX for direct capture of monoclonal antibodies from high titer cell culture fluids. Two resin candidates were selected from seven newer generation cation exchangers for their higher binding capacity and selectivity. Two monoclonal antibodies with widely differing pI values were used to evaluate the capability of CEX as a platform capture step. Screening of loading pH and conductivity showed both resins to be capable of directly capturing both antibodies from undiluted cell culture fluid. At appropriate acidic pH range, product loading of over 65 g/L resin was achieved for both antibodies. A systematic design of experiment (DOE) approach was used to optimize the elution conditions for the CEX step. Elution pH showed the most significant impact on clearance of host cell proteins (HCPs). Under optimal conditions, HCP reduction factors in the range of 9-44 were achieved on the CEX step based on the pI of the antibody. Apart from comparing CEX directly to Protein A as the capture method, material from either modality was also processed through the subsequent polishing steps to compare product quality at the drug substance level. Process performance and product quality was found to be acceptable using the non-affinity based process scheme. The results shown here present a cheaper and higher capacity generic capture method for high-titer antibody processes.

Small-molecule-based affinity chromatography method for antibody purification via nucleotide binding site targeting

The conserved nucleotide binding site (NBS), found within the Fab variable domain of antibodies, remains a not-so-widely known and underutilized site. Here we describe a novel affinity chromatography method that utilizes the NBS as a target for selectively purifying antibodies from complex mixtures. The affinity column was prepared by coupling indole butyric acid (IBA), which has a monovalent affinity for the NBS with a K(d) ranging between 1 and 8 μM, to ToyoPearl resin resulting in the NBS targeting affinity column (NBS(IBA)). The proof-of-concept studies performed using the chimeric pharmaceutical antibody rituximab demonstrated that antibodies were selectively captured and retained on the NBS(IBA) column and were successfully eluted by applying a mild NaCl gradient at pH 7.0. Furthermore, the NBS(IBA) column consistently yielded >95% antibody recovery with >98% purity, even when the antibody was purified from complex mixtures such as conditioned cell culture supernatant, hybridoma media, and mouse ascites fluid. The results presented in this study establish the NBS(IBA) column as a viable small-molecule-based affinity chromatography method for antibody purification with significant implications in industrial antibody production. Potential advantages of the NBS(IBA) platform are improved antibody batch quality, enhanced column durability, and reduced overall production cost.

Separation of antigens and antibodies by immunoaffinity chromatography

CONTEXT

Affinity chromatography is an efficient antibody, antigen and protein separation method based on the interaction between specific immobilized ligands and target antibody, antigen, and so on. Populations of available ligands can be used to separate antibodies or their Fab fragments. Similarly, antigens can be isolated by immunoaffinity chromatography (IAC) on immobilized antibodies of low affinity.

OBJECTIVE

This review describes the advantages, the applications, as well as the drawbacks, of IAC in the separation and purification of antibodies and antigens.

METHODS

The present review discussed all types of purification and isolation of antibodies and antigens by IAC, including purification of antibodies using immobilized and synthetic mimic proteins A, G and L; isolation of Fab fragments of antibodies; separation of antibodies against different antigen forms; isolation of antigens by immobilized antibodies and so on. These methods come from over 60 references compiled from all major databases.

RESULTS

Purification of antigens with antibodies should choose low-affinity antibodies to avoid denaturation of most proteins. Concern for cost and safety, prompted research activities focused on novel synthetic ligands with improved properties such as lower cost, avoidance of the risk of contamination associated with natural ligands of human or animal origin to isolate antibodies and antigens.

CONCLUSION

It is anticipated that the improvements of IAC will have impact not only on large-scale production of antibodies but also on the generation of new affinity-based methods for the increasing number of proteins and antibody derivatives available by protein engineering and the proteomics revolution.

Defining process design space for a hydrophobic interaction chromatography (HIC) purification step: application of quality by design (QbD) principles

The concept of design space has been taking root under the quality by design paradigm as a foundation of in-process control strategies for biopharmaceutical manufacturing processes. This paper outlines the development of a design space for a hydrophobic interaction chromatography (HIC) process step. The design space included the impact of raw material lot-to-lot variability and variations in the feed stream from cell culture. A failure modes and effects analysis was employed as the basis for the process characterization exercise. During mapping of the process design space, the multi-dimensional combination of operational variables were studied to quantify the impact on process performance in terms of yield and product quality. Variability in resin hydrophobicity was found to have a significant influence on step yield and high-molecular weight aggregate clearance through the HIC step. A robust operating window was identified for this process step that enabled a higher step yield while ensuring acceptable product quality.

Scale-up of protein purification: downstream processing issues

Large-scale chromatography operations continue to occupy a key position in the overall strategy for the downstream processing and purification of protein products for therapeutic use. Increasing product titres from mammalian cell culture has resulted in a trend to identify ways of improving the economics of product recovery and purification processes. In commercial manufacturing, a requirement exists to increase the scale of the chromatography operations, which are typically developed and optimised in small-scale experiments. This short review discusses the key factors in the chromatography process that need to be considered as the scale of the purification step is increased in order to maintain the purity and integrity of the product purified at smaller scale.