Development of a Novel Label-Free Subunit HILIC-MS Method for Domain-Specific Free Thiol Identification and Quantitation in Therapeutic Monoclonal Antibodies.

Cysteine residues are crucial for the formation of conserved disulfide bonds in therapeutic monoclonal antibodies (mAbs), which are essential for their folding and structural stability. The presence of free thiols in mAbs can indicate incomplete disulfide bond formation, potentially impacting the molecule's conformational stability. Free thiol quantitation has been achieved using labeling-based strategies such as maleimide and haloalkyl derivatives at both intact and peptide levels.

A PD-1-targeted, receptor-masked IL-2 immunocytokine that engages IL-2Rα strengthens T cell-mediated anti-tumor therapies.

The clinical use of interleukin-2 (IL-2) for cancer immunotherapy is limited by severe toxicity. Emerging IL-2 therapies with reduced IL-2 receptor alpha (IL-2Rα) binding aim to mitigate toxicity and regulatory T cell (Treg) expansion but have had limited clinical success. Here, we show that IL-2Rα engagement is critical for the anti-tumor activity of systemic IL-2 therapy.

In-Depth Host Cell Protein Analysis and Viral Protein Impurity Monitoring in Adeno-Associated Virus-Based Gene Therapy Products Using Optimized Wide Window Data-Dependent Acquisition Method.

Compared to other protein therapeutics, there is currently limited knowledge about the residual host cell proteins (HCPs) in adeno-associated virus (AAV)-based gene therapy products. This is primarily due to the lack of a robust and sensitive mass spectrometry-based method for HCP analysis in AAV samples. Existing liquid chromatography-mass spectrometry methods used for analyzing HCPs in therapeutic monoclonal antibodies (mAbs) often cannot be directly applied to AAVs, due to some unique characteristics of AAV samples encountered during their development such as limited sample availability/protein concentration and the presence of surfactants.

Distinct chemical degradation pathways of AAV1 and AAV8 under thermal stress conditions revealed by analytical anion exchange chromatography and LC-MS-based peptide mapping.

Adeno-associated virus (AAV)-based gene therapy is experiencing a rapid growth in the field of medicine and holds great promise in combating a wide range of human diseases. For successful development of AAV-based products, comprehensive thermal stability studies are often required to establish storage conditions and shelf life. However, as a relatively new modality, limited studies have been reported to elucidate the chemical degradation pathways of AAV products under thermal stress conditions.

Affinity-Resolved Size Exclusion Chromatography Coupled to Mass Spectrometry: A Novel Tool to Study the Attribute-and-Function Relationship in Therapeutic Monoclonal Antibodies.

Assessment of critical quality attributes (CQAs) is an important aspect during the development of therapeutic monoclonal antibodies (mAbs). Attributes that affect either the target binding or Fc receptor engagement may have direct impacts on the drug safety and efficacy and thus are considered as CQAs. Native size exclusion chromatography (SEC)-based competitive binding assay has recently been reported and demonstrated significant benefits compared to conventional approaches for CQA identification, owing to its faster turn-around and higher multiplexity.

An Online Native Mass Spectrometry Approach for Fast, Sensitive, and Quantitative Assessment of Adeno-Associated Virus Capsid Content Ratios.

Adeno-associated viruses (AAVs) have emerged as a leading platform for therapeutic gene delivery and offer tremendous potential in the treatment and prevention of human disease. The fast-paced development of this growing class of therapeutics, coupled with their intrinsic structural complexity, places a high demand on analytical methods capable of efficiently monitoring product quality to ensure safety and efficacy, as well as to support manufacturing and process optimization. Importantly, the presence and relative abundance of both empty and partially filled AAV capsid subpopulations are of principal concern, as these represent the most common product-related impurities in AAV manufacturing and have a direct impact on therapeutic potential.

Enrichment strategy and initial characterization of heterodimers enriched from a co-formulated cocktail of therapeutic antibodies against SARS-COV-2.

Co-formulation of multiple drug products is an efficient and convenient approach to simultaneously deliver multiple biotherapeutics with the potentially added benefit of a synergistic therapeutic effect. However, co-formulation also increases the risk of heteromeric interactions, giving rise to unique impurities with unknown efficacy and immunogenicity. Therefore, it is critical to develop methods to evaluate the risk of heteromers as an impurity that could affect potency, efficacy, and/or immunogenicity.

Discovery and Characterization of an Acid-Labile Serine-Lysine Cross-Link in Antibody High-Molecular-Weight Species Using a Multipronged Mass Spectrometry Approach.

Characterizing the cross-links responsible for the covalent high-molecular-weight (HMW) species in therapeutic monoclonal antibodies (mAbs) is of great importance as it not only provides a framework for risk assessment but also offers insights for process improvement. However, owing to the complexity and low abundance, identification of novel and unknown cross-links in mAb products can be very challenging. Here, applying a multipronged MS-based approach, we report the discovery of a novel covalent cross-link formed an imine bond between lysine and serine residues.

A generic platform to couple affinity chromatography with native mass spectrometry for the analysis of therapeutic monoclonal antibodies.

Affinity chromatography coupled with native mass spectrometry has emerged as a powerful tool for the analysis of therapeutic monoclonal antibodies (mAbs). Exploiting the specific interactions between mAbs and their ligands, these methods not only provide orthogonal means to study the highly complex mAb attributes, but also offer insights on their biological relevance. Despite the great promise, application of affinity chromatography - native mass spectrometry in routine mAb characterization has been limited, largely due to the complicated experimental set up.

A competitive binding-mass spectrometry strategy for high-throughput evaluation of potential critical quality attributes of therapeutic monoclonal antibodies.

Therapeutic monoclonal antibodies (mAbs) have a propensity to host a large number of chemical and enzymatical modifications that need to be properly assessed for their potential impact on target binding. Traditional strategies of assessing the criticality of these attributes often involve a laborious and low-throughput variant enrichment step prior to binding affinity measurement. Here, we developed a novel competitive binding-based enrichment strategy followed by mass spectrometry analysis (namely, competitive binding-MS) to achieve high-throughput evaluation of potential critical quality attributes in therapeutic mAbs.

Coupling Anion Exchange Chromatography with Native Mass Spectrometry for Charge Heterogeneity Characterization of Monoclonal Antibodies.

Despite the recent success of coupling anion exchange chromatography with native mass spectrometry (AEX-MS) to study anionic proteins, the utility of AEX-MS methods in therapeutic monoclonal antibody (mAb) characterization has been limited. In this work, we developed and optimized a salt gradient-based AEX-MS method and explored its utility in charge variant analysis of therapeutic mAbs. We demonstrated that, although the developed AEX-MS method is less useful for IgG1 molecules that have higher isoelectric points (ps), it is an attractive alternative for charge variant analysis of IgG4 molecules.

Post-Column Denaturation-Assisted Native Size-Exclusion Chromatography-Mass Spectrometry for Rapid and In-Depth Characterization of High Molecular Weight Variants in Therapeutic Monoclonal Antibodies.

The high molecular weight (HMW) size variants present in therapeutic monoclonal antibody (mAb) samples need to be closely monitored and characterized due to their impact on product safety and efficacy. Because of the complexity and often low abundances in final drug substance (DS) samples, characterization of such HMW species is challenging and traditionally requires offline enrichment of the HMW species followed by analysis using various analytical tools. Here, we report the development of a postcolumn denaturation-assisted native SEC-MS method that allows rapid and in-depth characterization of mAb HMW species directly from unfractionated DS samples.

Development of a chromatography-free method for high-throughput MS-based bioanalysis of therapeutic monoclonal antibodies.

Our objective was to test the feasibility of developing an LC-free, MS-based approach for high-throughput bioanalysis of humanized therapeutic monoclonal antibodies. A universal tryptic peptide from human IgG1, IgG3 and IgG4 was selected as the surrogate peptide for quantitation. After tryptic digestion, the surrogate peptide was fractionated via solid-phase extraction before being subjected to direct infusion-based MS/MS analysis.

Versatile, Sensitive, and Robust Native LC-MS Platform for Intact Mass Analysis of Protein Drugs.

Over the past several years, hyphenation of native (nondenaturing) liquid chromatography (nLC) methods, such as size exclusion chromatography (SEC), ion exchange chromatography (IEX), and hydrophobic interaction chromatography (HIC) with mass spectrometry (MS) have become increasingly popular to study the size, charge, and structural heterogeneity of protein drug products. Despite the availability of a wide variety of nLC-MS methods, an integrated platform that can accommodate different applications is still lacking. In this study, we described the development of a versatile, sensitive, and robust nLC-MS platform that can support various nLC-MS applications.

Characterization of Adeno-Associated Virus Capsid Proteins Using Hydrophilic Interaction Chromatography Coupled with Mass Spectrometry.

To support adeno-associated virus (AAV)-based gene therapy development, characterization of the three capsid viral proteins (VP; VP1/VP2/VP3) from recombinant AAV can offer insights on capsid identity, heterogeneity, and product and process consistency. Intact protein mass analysis is a rapid, reliable, and sensitive method to confirm AAV serotypes based on accurate mass measurement of the constituent capsid proteins. Compared to commonly applied reversed-phase liquid chromatography (RPLC) methods, we demonstrated that, using a wide-pore amide-bonded column, hydrophilic interaction chromatography (HILIC) could achieve improved separation of VPs from a variety of AAV serotypes using a generic method prior to MS detection.

An O-Labeling Assisted LC-MS Method for Accurate Quantitation of Unprocessed C-Terminal Lysine in Therapeutic Monoclonal Antibodies.

Unprocessed C-terminal lysine (C-term Lys) is one of the most common causes for the formation of basic variants in therapeutic monoclonal antibodies (mAbs). Although the C-term Lys variants are routinely quantified by a LC-MS-based peptide mapping method using the relative MS responses from both C-terminal peptides (with and without Lys), this approach often leads to overestimation of Lys-containing peptide due to the intrinsic difference in ionization efficiency. Herein, we report an O-labeling assisted LC-MS method, which takes advantage of the carboxypeptidase B-catalyzed Lys removal and O-labeling to achieve improved accuracy of C-term Lys quantitation.

Online coupling of analytical hydrophobic interaction chromatography with native mass spectrometry for the characterization of monoclonal antibodies and related products.

Native mass spectrometry (native MS) has seen tremendous development and an increase in application over the past decade for the study of proteins and protein complexes. Although conventionally performed using a static nanospray emitter in an offline fashion, native MS has been increasingly applied in hyphenated methods, where a wide variety of separation techniques are directly coupled to online native MS detection. Those new developments have greatly expanded the utility of native MS in protein biopharmaceutical characterization.

Coupling Mixed-Mode Size Exclusion Chromatography with Native Mass Spectrometry for Sensitive Detection and Quantitation of Homodimer Impurities in Bispecific IgG.

Detection and quantitation of homodimer impurities in therapeutic bispecific antibody (bsAb) drug products is essential to support development and quality control (QC) release. LC-MS-based techniques have been frequently applied for this analysis. However, sensitive detection of low-abundance homodimer impurities can still be challenging for regular workflows, which is largely due to the lack of chromatographic resolution between the impurities and the main bsAb species.

Genetic Differentiation of Eastern Honey Bee () Populations Across Qinghai-Tibet Plateau-Valley Landforms.

Many species of high-altitude plateaus tend to be narrowly distributed along river valleys at lower elevations due to a limitation of suitable habitats. The eastern honeybee () is such a species and this study explored the effects of long and narrow geographic distributions on honeybee populations. Genetic differentiation and diversity were assessed across populations of the southeastern Qinghai-Tibet Plateau.

Simple Approach for Improved LC-MS Analysis of Protein Biopharmaceuticals via Modification of Desolvation Gas.

LC-MS based analysis of protein biopharmaceuticals could benefit from improved data quality, which can subsequently lead to improved drug characterization with higher confidence and less ambiguity. In this study, we created a simple device to modify the desolvation gas on a Q-Exactive mass spectrometer and to demonstrate the utility in improving both peptide mapping analysis and intact mass analysis, the two most routinely and widely applied LC-MS techniques in protein biopharmaceutical characterization. By modifying the desolvation gas with acid vapor from propionic acid (PA) and isopropanol (IPA), the ion suppression effects from trifluoroacetic acid (TFA) in a typical peptide mapping method can be effectively mitigated, thus leading to improved MS sensitivity.

Ultrasensitive Characterization of Charge Heterogeneity of Therapeutic Monoclonal Antibodies Using Strong Cation Exchange Chromatography Coupled to Native Mass Spectrometry.

In therapeutic monoclonal antibody (mAb) development, charge heterogeneity of a mAb molecule is often associated with critical quality attributes and is therefore monitored throughout development and during QC release to ensure product and process consistency. Elucidating the cause of each charge variant species is an involved process that often requires offline fractionation by ion exchange chromatography (IEX) followed by mass spectrometry (MS) analysis, largely due to the incompatibility of conventional IEX buffers for direct MS detection. In this study, we have developed a method that combines a generic strong cation exchange (SCX) chromatography step with ultrasensitive online native MS analysis (SCX-MS) optimized for mAb separation and detection.

Characterization of product-related low molecular weight impurities in therapeutic monoclonal antibodies using hydrophilic interaction chromatography coupled with mass spectrometry.

Traditional SDS-PAGE method and its modern equivalent CE-SDS method are both widely applied to assess the purity of therapeutic monoclonal antibody (mAb) drug products. However, structural identification of low molecular weight (LMW) impurities using those methods has been challenging and largely based on empirical knowledges. In this paper, we present that hydrophilic interaction chromatography (HILIC) coupled with mass spectrometry analysis is a novel and orthogonal method to characterize such LMW impurities present within a purified mAb drug product sample.