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Your search keyword '"van de Merbel, Nico C."' showing total 179 results
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179 results on '"van de Merbel, Nico C."'

26. Advances in liquid chromatography tandem mass spectrometry (LC-MS-MS)-based quantitation of biopharmaceuticals in biological samples

Author

van de Merbel, Nico C.

Subjects
Biopharmaceutics, Mass spectrometry, Amino acids, Liquid chromatography, Chemistry, Science and technology
Abstract

Liquid chromatography coupled to tandem mass spectrometry (LC-MS-MS) has recently become a more and more popular alternative to traditional ligand-binding assays for the quantitative determination of biopharmaceuticals. LC-MS-MS offers several [...]

Published
2015

30. Biotransformation of Trastuzumab and Pertuzumab in Breast Cancer Patients Assessed by Affinity Enrichment and Ion-Exchange Chromatography

Author

Olaleye, Oladapo, Spanov, Baubek, Bults, Peter, van der Voort, Anna, Govorukhina, Natalia, Sonke, Gabe S., Horvatovich, Peter, van de Merbel, Nico C., and Bischoff, Rainer

Abstract

Therapeutic proteins (TPs) are known to be heterogeneous due to modifications that occur during the production process and storage. Modifications may also occur in TPs after their administration to patients due to in vivo biotransformation. Ligand binding assays, which are widely used in the bioanalysis of TPs in body fluids, are typically unable to distinguish such modifications. Liquid chromatography coupled to mass spectrometry is being increasingly used to study modifications in TPs, but its use to study in vivo biotransformation has been limited until now. We present a novel approach that combines affinity enrichment using Affimer reagents with ion-exchange chromatography (IEX) to analyze charge variants of the TPs trastuzumab and pertuzumab in plasma of patients undergoing therapy for HER2-positive breast cancer. Affimer reagents were immobilized via engineered Cys tags to maleimide beads, and the TPs were eluted under acidic conditions followed by rapid neutralization. The enriched TPs were analyzed by cation-exchange chromatography (IEX) using pH-gradient elution, resulting in the separation of about 20 charge variants for trastuzumab and about five charge variants for pertuzumab. A comparison between in vitro stressed TPs spiked into plasma, and TPs enriched from patient plasma showed that the observed profiles were highly similar. This indicates that in vitro stress testing in plasma can mimic the situation in patient plasma, as far as the generation of charge variants is concerned.SIGNIFICANCE STATEMENTThis research attempts to elucidate the modifications that occur in therapeutic proteins (TPs) after they have been administered to patients. This is important because there is little knowledge about the fate of TPs in this regard, and certain modifications could affect their efficiency. Our results show that the modifications discovered are most likely due to a chemical process and are not patient specific.

Published
2023
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35. Practical comparison of different approaches to speed up LC separations

Author

van de Merbel, Nico C., Giegold, Sascha, and Teutenberg, Thorsten

Subjects
Separation (Technology) -- Methods -- Usage -- Research -- Analysis, Liquid chromatography -- Analysis -- Research -- Usage -- Methods, Chemistry, Science and technology
Abstract

This article describes and compares a number of approaches to increase the speed of liquid chromatographic separations. On a standard LC column, a gain of a factor two in the [...]

Published
2007

44. High-sensitivity quantitation of a biopharmaceutical Nanobody® in plasma by single-cartridge multi-dimensional solid-phase extraction and UPLC-MS/MS

Author

Bronsema, Kees, Bischoff, Rainer, Bouche, Marie-Paule, Mortier, Kjell, van de Merbel, Nico C., Analytical Biochemistry, and Medicinal Chemistry and Bioanalysis (MCB)

Subjects
biopharmaceutical, Nanobody, LC-MS/MS, antibody-free, high sensitivity, oxygen exchange internal standard, multi-dimensional SPE, enzymatic digestion
Abstract

Background: A major challenge in protein quantitation based on enzymatic digestion of complex biological samples and subsequent LC-MS/MS analysis of a signature peptide is dealing with the high complexity of the matrix after digestion, which can reduce sensitivity considerably. For the quantitation of a 28-kDa biopharmaceutical protein, a single-cartridge, multi-dimensional (ion-exchange and reversed-phase) SPE procedure to selectively enrich a signature peptide from a plasma digest was developed, validated and applied. Results: With this procedure, sufficient selectivity was introduced to allow quantitation in 50 µL of plasma down to 10.0 ng/mL (~0.3 nM). An in-house prepared 18O-labeled form of the signature peptide was successfully used as internal standard. The developed procedure was validated for both human and rabbit plasma. Plasma samples from a pre-clinical trial were analyzed with the developed LC-MS/MS method and compared to a conventional ligand binding assay. The results of the LC-MS/MS assay and the ligand binding assay were in good agreement (r2 >0.85) Conclusions: The combination of ion-exchange and (high-pH) reversed-phase SPE principles allowed the sensitive and selective LC-MS/MS quantitation of the Nanobody in digested plasma without the use of antibodies for sample clean-up. When appropriate precautions are taken, the preparation of an 18O-labeled peptide for use as internal standard is a practical and economical alternative to custom synthesis.

Published
2015

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