Atypical Asparagine Deamidation of NW Motif Significantly Attenuates the Biological Activities of an Antibody Drug Conjugate.

Asparagine deamidation is a post-translational modification (PTM) that converts asparagine residues into iso-aspartate and/or aspartate. Non-enzymatic asparagine deamidation is observed frequently during the manufacturing, processing, and/or storage of biotherapeutic proteins. Depending on the site of deamidation, this PTM can significantly impact the therapeutic's potency, stability, and/or immunogenicity.

Multiplex Bioanalytical Methods for Comprehensive Characterization and Quantification of the Unique Complementarity-Determining-Region Deamidation of MEDI7247, an Anti-ASCT2 Pyrrolobenzodiazepine Antibody-Drug Conjugate.

Deamidation, a common post-translational modification, may impact multiple physiochemical properties of a therapeutic protein. MEDI7247, a pyrrolobenzodiazepine (PBD) antibody-drug conjugate (ADC), contains a unique deamidation site, N102, located within the complementarity-determining region (CDR), impacting the affinity of MEDI7247 to its target. Therefore, it was necessary to monitor MEDI7247 deamidation status in vivo.

Correction: Theoretical predictions and experimental verifications of SERS detection in colorants.

[This corrects the article DOI: 10.1039/D3RA01584J.].

Identification of a CE-SDS shoulder peak as disulfide-linked fragments from common C2 cleavages in IgGs and IgG-like bispecific antibodies.

Fragmentation is a well-characterized degradation pathway of therapeutic antibodies and is usually monitored by capillary electrophoresis-sodium dodecyl sulfate (CE-SDS). Although fragments due to cleavage in C2 domains linked by intrachain disulfide bonds are common and can be detected by reduced reversed-phase - liquid chromatography mass spectrometry (RP-LCMS) and reduced CE-SDS methods, their separation in nonreduced CE-SDS (nrCE-SDS) has not been reported but speculated as comigrating with intact IgG. A shoulder peak in nrCE-SDS was observed in the stability samples of an IgG-like bispecific antibody and was determined to be mainly caused by fragments from clipping at the C-terminus of leucine (L)306 or L309 (EU numbering) in the C2 domain of both heavy chains (HCs) and, to a lesser degree, at the C-terminus of L182 in the C1 domain of the knob HC.

Characterization of N-Terminal Glutamate Cyclization in Monoclonal Antibody and Bispecific Antibody Using Charge Heterogeneity Assays and Hydrophobic Interaction Chromatography.

N-terminal glutamate (E) cyclization to form pyroglutamate (pE) generates charge heterogeneities for mAbs and proteins. Thus far, pE formation rate in lyophilized formulation as compared to in liquid formulation has not been reported. Impact of pE on antibody biological activity has only been predicted or assessed using stressed samples that may contain other confounding degradations besides pE.

Development of a mechanism of action-reflective, dual target cell-based reporter bioassay for a bispecific monoclonal antibody targeting human CTLA-4 and PD-1.

T-cell-mediated immunotherapy has generated much excitement after the success of therapeutic biologics targeting immune checkpoint molecules. Bispecific antibodies (BsAbs) that recognize two antigen targets are a fast-growing class of biologics offering promising clinical benefits for cancer immunotherapy. Due to the complexity of the molecule structure and the potential mechanism of action (MOA) that involves more than one signaling pathway, it is critical to develop appropriate bioassays for measuring potency and characterizing the biological properties of BsAbs.

Nonspecific cleavages arising from reconstitution of trypsin under mildly acidic conditions.

Tryptic digestion of proteins followed by liquid chromatography with tandem mass spectrometry analysis is an extensively used approach in proteomics research and biopharmaceutical product characterization, owing to the high level of cleavage fidelity produced with this technique. However, nonspecific trypsin cleavages have been frequently reported and shown to be related to a number of digestion conditions and predigestion sample treatments. In this work, we reveal that, for a number of commercial trypsins, reconstitution and storage conditions can have a significant impact on the occurrence of trypsin nonspecific cleavages.

Analytical characterization of coformulated antibodies as combination therapy.

When two therapeutic agents are combined in a single formulation, i.e., coformulated, the quality and safety of the individual agents must be preserved.

Impact of enzymatic reduction on bivalent bispecific antibody fragmentation and loss of product purity upon reoxidation.

Antibody disulfide bond (DSB) reduction during manufacturing processes is a widely observed phenomenon attributed to host cell reductases present in harvest cell culture fluid. Enzyme-induced antibody reduction leads to product fragments and aggregates that increase the impurity burden on the purification process. The impact of reduction on bivalent bispecific antibodies (BisAbs), which are increasingly entering the clinic, has yet to be investigated.

An Automated and Qualified Platform Method for Site-Specific Succinimide and Deamidation Quantitation Using Low-pH Peptide Mapping.

mAbs undergo several post-translational modifications, including the formation of succinimide from the deamidation of asparagine or the isomerization of aspartic acid. Because of the potential impact of succinimide formation on the biological activity of mAbs, detection and quantification of this species is a key area of interest for the pharmaceutical industry. However, studies assessing succinimide stability have been limited, and methods developed to monitor succinimide are either product specific or not robust.

Site-specific antibody-drug conjugate heterogeneity characterization and heterogeneity root cause analysis.

Site-specific antibody-drug conjugates (ADCs) are designed to overcome the heterogeneity observed with first-generation ADCs that use random conjugation to surface-exposed lysine residues or conjugation to interchain disulfide bonds. Despite significantly enhanced homogeneity, however, the production of site-specific ADCs yields some process-related species heterogeneity, including stereoisomers, unconjugated antibody, underconjugated species, and overconjugated species. An elevated level of size variants, such as heavy chain-light chain species (half ADC), heavy chain-heavy chain-light chain species, and light chain species, is also observed with the final site-specific ADC product.

A method to directly analyze free-drug-related species in antibody-drug conjugates without sample preparation.

Residual free-drug-related species that are present in antibody-drug conjugates (ADC) are a potential safety risk to patients and are therefore categorized as a critical quality attribute that must be strictly monitored and controlled. Among the many analytical methods developed for free-drug analysis, reversed-phase liquid chromatography (RP-LC) is the most common approach. Conventional RP-LC methods for free-drug analysis, however, involve labor-intensive sample preparation.

Charge variants characterization and release assay development for co-formulated antibodies as a combination therapy.

Combination therapy is a fast-growing strategy to maximize therapeutic benefits to patients. Co-formulation of two or more therapeutic proteins has advantages over the administration of multiple medications, including reduced medication errors and convenience for patients. Characterization of co-formulated biologics can be challenging due to the high degree of similarity in the physicochemical properties of co-formulated proteins, especially at different concentrations of individual components.

Characterization and quantification of succinimide using peptide mapping under low-pH conditions and hydrophobic interaction chromatography.

Characterization of asparagine deamidation and aspartic acid isomerization is an important aspect of biotherapeutic protein analysis due to the potential negative effect of these modifications on drug efficacy and stability. Succinimide has long been known to be an intermediate product of asparagine deamidation and aspartic acid isomerization, but despite the key role of succinimide in these reactions, its analysis remains challenging due to its instability. We have developed a paradigm in which two interlinked analytical methods are used to develop an optimized approach to analyze succinimide.

Cathepsin L Causes Proteolytic Cleavage of Chinese-Hamster-Ovary Cell Expressed Proteins During Processing and Storage: Identification, Characterization, and Mitigation.

A stochastic approach of copurification of the protease Cathepsin L that results in product fragmentation during purification processing and storage is presented. Cathepsin L was identified using mass spectroscopy, characterization of proteolytic activity, and comparison with fragmentation patterns observed using recombinant Cathepsin L. Cathepsin L existed in Chinese hamster ovary cell culture fluids obtained from cell lines expressing different products and cleaved a variety of recombinant proteins including monoclonal antibodies, antibody fragments, bispecific antibodies, and fusion proteins.

A systematic approach for analysis and characterization of mispairing in bispecific antibodies with asymmetric architecture.

Immunoglobulin G-like bispecific antibodies with asymmetric architecture are among the most widely used bispecific antibody formats for diagnostic and therapeutic applications. The primary technical challenge for this format is how to achieve correctly paired assembly of four unique polypeptide chains. Advances in protein engineering and process development are being used to overcome these challenges and are driving a corresponding demand for sensitive analytical tools to monitor and control mispaired species.

Characterization and analysis of scFv-IgG bispecific antibody size variants.

Bispecific antibodies are an emergent class of biologics that is of increasing interest for therapeutic applications. In one bispecific antibody format, single-chain variable fragments (scFv) are linked to or inserted in different locations of an intact immunoglobulin G (IgG) molecule to confer dual epitope binding. To improve biochemical stability, cysteine residues are often engineered on the heavy- and light-chain regions of the scFv to form an intrachain disulfide bond.

A Quadrupole Dalton-based multi-attribute method for product characterization, process development, and quality control of therapeutic proteins.

During manufacturing and storage process, therapeutic proteins are subject to various post-translational modifications (PTMs), such as isomerization, deamidation, oxidation, disulfide bond modifications and glycosylation. Certain PTMs may affect bioactivity, stability or pharmacokinetics and pharmacodynamics profile and are therefore classified as potential critical quality attributes (pCQAs). Identifying, monitoring and controlling these PTMs are usually key elements of the Quality by Design (QbD) approach.

Effects of antibody disulfide bond reduction on purification process performance and final drug substance stability.

Antibody disulfide bond reduction during monoclonal antibody (mAb) production is a phenomenon that has been attributed to the reducing enzymes from CHO cells acting on the mAb during the harvest process. However, the impact of antibody reduction on the downstream purification process has not been studied. During the production of an IgG mAb, antibody reduction was observed in the harvested cell culture fluid (HCCF), resulting in high fragment levels.

Qualification of a Quantitative Method for Monitoring Aspartate Isomerization of a Monoclonal Antibody by Focused Peptide Mapping.

Unlabelled: Aspartate (Asp) isomerization is a common post-translational modification of recombinant therapeutic proteins that can occur during manufacturing, storage, or administration. Asp isomerization in the complementarity-determining regions of a monoclonal antibody may affect the target binding and thus a sufficiently robust quality control method for routine monitoring is desirable. In this work, we utilized a liquid chromatography-mass spectrometry (LC/MS)-based approach to identify the Asp isomerization in the complementarity-determining regions of a therapeutic monoclonal antibody.

Double-peak elution profile of a monoclonal antibody in cation exchange chromatography is caused by histidine-protonation-based charge variants.

We have systemically investigated unusual elution behaviors of an IgG4 (mAb A) in cation exchange chromatography (CEX). This mAb A exhibited two elution peaks under certain conditions when being purified by several strong CEX columns. When either of the two peaks was isolated and re-injected on the same column, the similar pattern was observed again during elution.