LC-MS/MS-PRM Quantification of IgG Glycoforms Using Stable Isotope Labeled IgG1 Fc Glycopeptide Standard

Technical, preclinical, and clinical developments of Fc-glycan-specific antibody-drug conjugates

Antibody-drug conjugates (ADCs) have emerged as a powerful avenue in the therapeutic treatment of cancer. Site-specific antibody-drug conjugations represent the latest trend in the development of ADCs, addressing the limitations of traditional random conjugation technologies. This article summarizes the innovative development of Fc-glycan-specific ADCs (gsADCs), which utilize the conserved Fc N-glycan as the anchor point for site-specific conjugation. This approach offers significant strengths, including improved ADC homogeneity and overall hydrophilicity, enhanced pharmacokinetics and therapeutic index, and potentially reduced Fc receptor-mediated side effects. Currently dozens of gsADCs are in different preclinical and clinical development stages. Notably, JSKN003 and IBI343 have demonstrated promising results in phase 1 trials and are advancing into phase 3 studies. This review discusses the advantages of Fc-glycan-conjugation, various glycan-specific conjugation techniques, and the preclinical and clinical development of gsADCs. While challenges such as increased manufacturing cost for large-scale production need continuous innovation to overcome and there are different opinions regarding the pros and cons of reduced/diminished affinities to Fc gamma receptors, ongoing research and clinical progress underscore the potential of gsADCs to renovate ADC cancer therapy.

Serum N-Glycan Changes in Rats Chronically Exposed to Glyphosate-Based Herbicides

Glyphosate, the active ingredient in many herbicides, has been widely used in agriculture since the 1970s. Despite initial beliefs in its safety for humans and animals due to the absence of the shikimate pathway, recent studies have raised concerns about its potential health effects. This study aimed to identify glycomic changes indicative of glyphosate-induced toxicity. Specifically, the study focused on profiling N-glycosylation, a protein post-translational modification increasingly recognized for its involvement in various disorders, including neurological conditions. A comprehensive analysis of rat serum N-glycomics following chronic exposure to glyphosate-based herbicides (GBH) was conducted using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results revealed significant changes in the N-glycan profile, particularly in sialylated and sialofucosylated N-glycans. The analysis of N-glycans across gender subgroups provided insights into gender-specific responses to GBH exposure, with the male rats exhibiting a higher susceptibility to these N-glycan changes compared to females. The validation of significantly altered N-glycans using parallel reaction monitoring (PRM) confirmed their expression patterns. This study provides novel insights into the impact of chronic GBH exposure on serum N-glycan composition, with implications for assessing glyphosate toxicity and its potential neurological implications.

Simple Routes to Stable Isotope-Coded Native Glycans

Understanding the biological role of protein-linked glycans requires the reliable identification of glycans. Isomer separation and characterization often entail mass spectrometric detection preceded by high-performance chromatography on porous graphitic carbon. To this end, stable isotope-labeled glycans have emerged as powerful tools for retention time normalization. Hitherto, such standards were obtained by chemoenzymatic or purely enzymatic methods, which introduce, e.g., 13C-containing N-acetyl groups or galactose into native glycans. Glycan release with anhydrous hydrazine opens another route for heavy isotope introduction via concomitant de-N-acetylation. Here, we describe that de-N-acetylation can also be achieved with hydrazine hydrate, which is a more affordable and less hazardous reagent. Despite the slower reaction rate, complete conversion is achievable in 72 h at 100 °C for glycans with biantennary glycans with or without sialic acids. Shorter incubation times allow for the isolation of intermediate products with a defined degree of free amino groups, facilitating introduction of different numbers of heavy isotopes. Mass encoded glycans obtained by this versatile approach can serve a broad range of applications, e.g., as internal standards for isomer-specific studies of N-glycans, O-glycans, and human milk oligosaccharide by LC-MS on either porous graphitic carbon or─following permethylation─on reversed phase.

Targeted Glycoproteomics Analysis Using MRM/PRM Approaches

MS-target analyses are frequently utilized to analyze and validate structural changes of biomolecules across diverse fields of study such as proteomics, glycoproteomics, glycomics, lipidomics, and metabolomics. Targeted studies are commonly conducted using multiple reaction monitoring (MRM) and parallel reaction monitoring (PRM) techniques. A reliable glycoproteomics analysis in intricate biological matrices is possible with these techniques, which streamline the analytical workflow, lower background interference, and enhance selectivity and specificity.