Biopharmaceuticals and Protein Analysis

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In the second part of this review of the current state of HIC, some practical considerations are explained, including method development, selection of the phase system, combined salt systems, and possibilities to combine HIC with other chromatographic modes.

The diverse nature of oligonucleotide therapeutics leads to the requirement for multiple separation methods to characterize quality attributes. Highly chemically-modified to improve efficacy and resilience to nucleases, they are challenging to analyse using a single method. This article discusses multiple chromatographic separation methods, and the benefits of mass spectrometry (MS).

Cellular and gene therapies (CGTs) have contributed significantly to the improvement of clinical outcomes for patients in the recent years. This paper discusses a range of physicochemical methods that play an important role in the difficult characterization of viral vectors, to meet the unique needs of CGT manufacturing process development, process and product characterization, and the quality control testing of these materials.

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Single-column (batch) chromatography, involving two or more successive single-column (batch) chromatographic steps, is a standard approach for purifying biopharmaceuticals. Step one, known as the capture step, is used to remove product-related impurities, and step two, the polishing step, is used to remove product-related impurities. Here we present and illustrate the advantages of continuous chromatography for these separations: capture simulated moving bed (captureSMB) for the capture step and multicolumn countercurrent solvent gradient purification (MCSGP) for polishing.

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Post-translational modifications are potential critical quality attributes (pCQAs) routinely assessed in biotherapeutic development. Glycosylation is one of the most important attributes to assess because it affects protein function as well as antigen receptor binding. N-glycosylation of asparagine residues is the most common pCQA assessed during monoclonal antibody (mAb) therapeutic development. There are a few protocols to assess and quantitate N-glycans, but the most common approach is through an enzymatic release and labelling procedure, followed by separation and detection. This article demonstrates the method development considerations for sample preparation and chromatographic analysis of N-glycans of therapeutic mAbs.

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The dried blood spot (DBS) sampling technique has been around for decades, predominantly for small molecules and mainly in newborn screening. Although determination of proteins after DBS sampling is usually performed with immunometric assays, the combination with mass spectrometry (MS) is gaining interest. This article provides an overview of DBS sampling for mass spectrometry-based protein analysis. The first part will focus on clinical applications for DBSs and on sampling other biological matrices apart from whole blood, including dried matrix spots (DMSs). The second part will explore the new frontiers of the DBS sampling technology, including novel sampling materials/devices, and novel combinations with mass spectrometry. Examples of use in both qualitative and quantitative protein analysis are highlighted as well as examples using both bottom-up and top-down proteomics approaches.

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Size-exclusion chromatography (SEC), with the use of ammonium acetate buffer, can be coupled on-line to electrospray ionization MS for the characterization of size variants of therapeutic monoclonal antibodies (mAbs). A quadrupole time-of-flight (QTOF) MS system was employed, and the MS method was optimized to achieve favorable sensitivity for high-mass detection, while maintaining the structural integrity of the aggregates (or high molecular weight species) and fragments (or low molecular weight species).

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A method was developed for the molecular weight characterization of heterogeneous polymer mixtures, such as heparins and glatiramer acetate, noting that single molecular structures are not adequate for creating a molecular weight calibration curve. That limitation is overcome in this work, which demonstrates method validation and application to process samples.

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To fully characterize a protein biopharmaceutical, it must be broken down into smaller segments (peptides). Several high performance liquid chromatography (HPLC) techniques can be used to provide a wealth of information on everything from post-translational modifications (PTMs) to the glycoprofile to information on similarity when characterizing biosimilars.