Quantitative LC/ESI-SRM/MS of antibody biopharmaceuticals: use of a homologous antibody as an internal standard and three-step method development

Integration of protein L-immobilized epoxy magnetic bead capture with LC-MS/MS for therapeutic monoclonal antibody quantification in serum

In recent years, there has been a growing interest in the thriving monoclonal antibody (mAb) industry due to the wide utilization of mAbs in clinical therapies. Robust and accurate bioanalytical methods are required to enable fast quantification of mAbs in biological matrices, especially in the context of pharmacokinetics (PKs)/pharmacodynamics (PDs) and therapeutic drug monitoring (TDM) studies. In this investigation, we presented a novel immuno-magnetic capture coupled with a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method designed for the quantification of immunoglobulin G-kappa-based mAbs in biological fluids. The immunoaffinity absorbent for mAb drug purification was meticulously crafted by immobilizing protein L onto monosize, magnetic poly(glycidyl methacrylate) (m-pGMA) beads, synthesized through dispersion polymerization. The microspheres were acquired with an average size of 1.6 μm, and the optimal binding of mAbs from the aqueous mAb solution was determined to be 45.82 mg g-1. The quantification of mAbs in 10 μL serum samples was achieved through affinity purification using m-pGMA@protein L beads (employing rituximab as an internal standard (IS)), on-bead reduction, and rapid tryptic digestion. Remarkably, the entire process, taking less than 2.5 hours, held significant potential for simplifying pretreatment procedures and minimizing analytical time. Furthermore, the developed method underwent validation in accordance with the European Medicines Agency (EMA) guidelines. The assay demonstrated commendable linearity within the 2-400 μg mL-1 range for both daratumumab and pembrolizumab. Intra- and inter-assay coefficients of variation fell within the range of 0.7% to 13.4%, meeting established acceptance criteria. Other validation parameters also conformed to regulatory standards. Ultimately, the efficacy of the method was substantiated in a pharmacokinetic study following a single-dose intravenous administration to mice, underscoring its applicability and reliability in real-world scenarios.

A rapid and universal liquid chromatograph-mass spectrometry-based platform, refmAb-Q nSMOL, for monitoring monoclonal antibody therapeutics

Accurate multiplexed quantitation of unique signature peptides derived from monoclonal antibody therapeutics with a universal reference antibody refmAb-Q using Fab-selective proteolysis nSMOL coupled with LC-MS/MS.

A generic sample preparation method for the multiplex analysis of seven therapeutic monoclonal antibodies in human plasma or serum with liquid chromatography-tandem mass spectrometry

Due to the increasing number of therapeutic monoclonal antibodies (mAbs) used in the clinic, there is an increasing need for robust analytical methods to quantify total mAb concentrations in human plasma for clinical studies and therapeutic drug monitoring. We developed an easy, rapid, and robust sample preparation method for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The method was validated for infliximab (IFX), rituximab (RTX), cetuximab (CTX), dupilumab (DPL), dinutuximab (DNX), vedolizumab (VDZ), and emicizumab (EMZ). Saturated ammonium sulfate (AS) was used to precipitate immunoglobulins in human plasma. After centrifugation, supernatant containing albumin was decanted, and the precipitated immunoglobulin fraction was re-dissolved in buffer containing 6M guanidine. This fraction was then completely denatured, reduced, alkylated, and trypsin digested. Finally, signature peptides from the seven mAbs were simultaneously quantified on LC-MS/MS together with their internal standards stable isotopically labeled peptide counterparts. The linear dynamic ranges (1 - 512 mg/L) of IFX, CTX, RTX, and EMZ showed excellent (R2 > 0.999) linearity and those of DPL, DNX, and VDZ showed good (R2 > 0.995) linearity. The method was validated in accordance with the EMA guidelines. EDTA plasma, sodium citrate plasma, heparin plasma, and serum yielded similar results. Prepared samples were stable at room temperature (20°C) and at 5°C for 3 days, and showed no decline in concentration for all tested mAbs. This described method, which has the advantage of an easy, rapid, and robust pre-analytical sample preparation, can be used as a template to quantify other mAbs in human plasma or serum.

Bottom-up sample preparation for the LC-MS/MS quantification of anti-cancer monoclonal antibodies in bio matrices

Therapeutic monoclonal antibodies (mAbs) are rapidly taking over the treatment of many malignancies, and an astonishing number of mAbs is in development. This causes a high demand for quantification of mAbs in biomatrices both for measuring therapeutic mAb concentrations and to support pharmacokinetics and pharmacodynamics studies. Conventionally, ligand-binding assays are used for these purposes, but LC-MS is gaining popularity. Although intact (top-down) and subunit (middle-down) mAb quantification is reported, signature peptide (bottom-up) quantification is currently most advantageous. This review provides an overview of the reported bottom-up mAb quantification methods in biomatrices as well as general recommendations regarding signature peptide and internal standard selection, reagent use and optimization of digestion in bottom-up quantification methods.

Determination of Cetuximab in Plasma by Liquid Chromatography-High-Resolution Mass Spectrometry Orbitrap With a Stable Labeled 13C,15N-Cetuximab Internal Standard

BACKGROUND

Cetuximab (CTX) is a chimeric IgG1 Kappa monoclonal antibody used to treat head and neck cancer and colorectal cancer. Previous clinical studies indicated that the pharmacokinetics of CTX influences patient survival. Thus, individualizing CTX treatment by measuring trough levels of the drug in plasma could have a major impact on clinical efficacy.

METHODS

To measure these levels, a full-length stable isotope-labeled CTX standard was used in a generic, rapid, and high-throughput sample preparation protocol based on IgG capture followed by trypsin digestion, on-line solid-phase extraction cleanup, and liquid chromatography-high resolution mass spectrometry (LC-HRMS).

RESULTS

The optimized method displayed good analytical performance and was linear over a range from 5 to 150 mcg/mL. The within-run and between-run imprecision of the assay were equal to or less than 10%, for 6 replicates at 3 different concentrations and for runs performed on 5 separate days. The plasma CTX concentrations in 19 patients were also determined.

CONCLUSIONS

The results showed that quantification of mAb in clinical samples does not strictly require a tandem mass spectrometry system, and LC-HRMS is also relevant in this context. This first study implementing a quantitative LC-HRMS assay with a specific stable isotope-labeled mAb internal standard paves the way for more robust clinical monitoring of anticancer mAbs.

Six-step workflow for the quantification of therapeutic monoclonal antibodies in biological matrices with liquid chromatography mass spectrometry - A tutorial

The promising pipeline of therapeutic monoclonal antibodies (mAbs) demands robust bioanalytical methods with swift development times for pharmacokinetic studies. Over the past decades ligand binding assays were the methods of choice for absolute quantification. However, the production of the required anti-idiotypic antibodies and ligands limits high-throughput method development for sensitive, accurate, and reproducible quantification of therapeutic mAbs. In recent years, high-resolution liquid chromatography tandem mass-spectrometry (LC-MS) systems have enabled absolute quantification of therapeutic mAbs with short method development times. These systems have additional benefits, such as a large linear dynamic range, a high specificity and the option of multiplexing. Here, we briefly discuss the current strategies for the quantification of therapeutic mAbs in biological matrices using LC-MS analysis based on top-down and middle-down quantitative proteomics. Then, we present the widely used bottom-up method in a six-step workflow, which can be used as guidance for quantitative LC-MS/MS method development of mAbs. Finally, strengths and weaknesses of the bottom-up method, which currently provides the most benefits, are discussed in detail.