Systematic Development of a Size Exclusion Chromatography Method for a Monoclonal Antibody with High Surface Aggregation Propensity (SAP) Index

Mini review for niche downstream processes

We review here several niche downstream purification processes that are not covered by other articles in this special issue. The first is the use of activated carbon to capture contaminants and clarify culture medium for purification of proteins, including antibodies. Flow-through operation of the activated carbon filter showed over 80 % recovery of antibodies with 10--fold reduction of host cell proteins and effective lipopolysaccharide and virus removal. The second is salt or arginine-tolerant column chromatography, in which the respective resins, such as hydroxyapatite and mixed-mode resins, can bind proteins in the presence of salt or arginine at high concentrations. Effective use of arginine was also suggested in size exclusion and affinity chromatography. The last is the isolation of proteins using gel electrophoresis and simple extraction procedure. These technologies offer simple and cost-effective methods for purifying proteins and protein complexes in the native state.

A Novel Size Exclusion Chromatography Method for the Analysis of Monoclonal Antibodies and Antibody-drug Conjugates by Using Sodium Iodide in the Mobile Phase

PURPOSES

Size exclusion chromatography (SEC) is widely used to characterize molecular size variants of antibody drugs. However, SEC analysis is hindered by secondary interactions (or nonspecific interactions) between proteins and stationary phase packing, which result in poor column efficiency. Previous studies have reported that chaotropic salt can inhibit these interactions, but the corresponding applications of this aspect are relatively rare. Therefore, this study introduces a novel approach using sodium iodide (NaI) as a mobile-phase component in SEC and investigates the influence of the mobile-phase composition on secondary interactions.

METHODS

SEC analysis was performed on one antibody-drug conjugate and four monoclonal antibodies (mAbs) using three different mobile-phase systems (i.e., sodium chloride/L-arginine hydrochloride/NaI mobile phases system) to compare the column efficiency. Subsequently, mAb-1 was used as a model to investigate the effects of these factors on secondary interactions by adjusting the ionic strength (salt concentration) and pH of the NaI mobile-phase system.

RESULTS

NaI exhibits superior column efficiency performance in the SEC analysis of most products. The ionic strength will affect nonideal electrostatic and hydrophobic interaction. An appropriate ionic strength can inhibit electrostatic interactions, while an excessive ionic strength increases hydrophobic interactions. pH primarily influences electrostatic interactions. Determining the appropriate pH necessitates consideration of the isoelectric point of the protein and the pH tolerance of the column.

CONCLUSIONS

In SEC analysis, using NaI as the salt component in the mobile phase reduces secondary interactions and improves column efficiency. This approach is advantageous for samples with intense secondary interactions and is a suitable alternative.

Size exclusion chromatography of biopharmaceutical products: From current practices for proteins to emerging trends for viral vectors, nucleic acids and lipid nanoparticles

The 21st century has been particularly productive for the biopharmaceutical industry, with the introduction of several classes of innovative therapeutics, such as monoclonal antibodies and related compounds, gene therapy products, and RNA-based modalities. All these new molecules are susceptible to aggregation and fragmentation, which necessitates a size variant analysis for their comprehensive characterization. Size exclusion chromatography (SEC) is one of the reference techniques that can be applied. The analytical techniques for mAbs are now well established and some of them are now emerging for the newer modalities. In this context, the objective of this review article is: i) to provide a short historical background on SEC, ii) to suggest some clear guidelines on the selection of packing material and mobile phase for successful method development in modern SEC; and iii) to highlight recent advances in SEC, such as the use of narrow-bore and micro-bore columns, ultra-wide pore columns, and low-adsorption column hardware. Some important innovations, such as recycling SEC, the coupling of SEC with mass spectrometry, and the use of alternative detectors such as charge detection mass spectrometry and mass photometry are also described. In addition, this review discusses the use of SEC in multidimensional setups and shows some of the most recent advances at the preparative scale. In the third part of the article, the possibility of SEC for the characterization of new modalities is also reviewed. The final objective of this review is to provide a clear summary of opportunities and limitations of SEC for the analysis of different biopharmaceutical products.

Accelerated development of a SEC-HPLC procedure for purity analysis of monoclonal antibodies using design of experiments

The complex structure of biopharmaceutical products poses an inherent need for their thorough characterization to ensure product quality, safety, and efficacy. Analytical size exclusion chromatography (SEC) is a widely used technique throughout the development and manufacturing of monoclonal antibodies (mAbs) which quantifies product size variants such as aggregates and fragments. Aggregate and fragment content are critical quality attributes (CQAs) in mAb products, as higher contents of such size heterogeneities impact product quality. Historically, SEC methods have achieved sufficient separation between the high molecular weight (HMW) species and the main product. In contrast, some low molecular weight (LMW) species are often not sufficiently different in molecular mass from the main product, making it difficult to achieve appropriate resolutions between the two species. This lack of resolution makes it difficult to consistently quantify the LMW species in mAb-based therapeutics. The following work uses a design of experiments (DoE) approach to establish a robust analytical SEC procedure by evaluating SEC column types and mobile phase compositions using two mAb products with different physiochemical properties. The resulting optimized procedure using a Waters™ BioResolve column exhibits an improved ability to resolve and quantify mAb size variants, highlighting improvement in the resolution of the LMW species. Additionally, the addition of L-arginine as a mobile phase additive showed to reduce secondary interactions and was beneficial in increasing the recoveries of the HMW species.