Interference from anti-drug antibodies on the quantification of insulin: a comparison of an LC-MS/MS assay and immunoassays

Aim: This study aims to compare the anti-drug antibody (ADA) interference in four pharmacokinetic (PK) assays across different platforms (AlphaLISA, Gyrolab, LC-MS/MS) and to devise a strategy for ADA interference mitigation to improve the accuracy of measured drug in total PK assays.Materials & methods: Spiked test samples, created to achieve different ADA concentrations in human serum also containing an insulin analogue, were analyzed alongside pooled clinical samples using four assays.Results & conclusion: Interference was observed in all platforms. A novel approach using the Gyrolab mixing CD, including acid dissociation in the PK assay, significantly reduced interference and thereby improved relative error from >99% to ≤20% yielding measurements well within the acceptance criteria. Clinical sample results reinforced findings from the test samples.

Generic Enrichment Method for Liquid Chromatography-Multiple Reaction Monitoring-Mass Spectrometry Assay for Quantitative Measurement of Biological Therapeutics in Serum

PURPOSE

The study aims to leverage the capabilities of Liquid Chromatography-Multiple Reaction Monitoring Mass Spectrometry (LC-MRM), a key technique in quantifying therapeutic proteins in pharmacokinetic studies. The focus is on demonstrating an enrichment method using ProteoMiner beads, which can be integrated with LC-MRM to detect low-abundance biotherapeutics in serum, such as monoclonal antibodies and gene therapy products.

METHODS

The ProteoMiner enrichment method was employed and integrated with LC-MRM. The lower limit of quantification of serum drug substance concentrations was compared with that achievable with immuno-enrichment. The method used commercially available reagents, eliminating the need for assay-specific antibodies and reducing potential bias and development time.

RESULTS

The ProteoMiner enrichment method showed comparable performance to immuno-enrichment, meeting traditional assay requirements in terms of precision, accuracy, and specificity.

CONCLUSIONS

The ProteoMiner enrichment method, when combined with LC-MRM, offers a reliable and efficient alternative to immuno-enrichment for detecting and quantifying low-abundance biotherapeutics in serum. This approach, which uses commercially available reagents, can eliminate the bias and time associated with the development of assay-specific antibodies. It holds significant potential for accelerating pharmacokinetic analysis in both early and late stages of pharmaceutical development.

Liquid-phase separations coupled with ion mobility-mass spectrometry for next-generation biopharmaceutical analysis

INTRODUCTION

The pharmaceutical industry continues to expand its search for innovative biotherapeutics. The comprehensive characterization of such therapeutics requires many analytical techniques to fully evaluate critical quality attributes, making analysis a bottleneck in discovery and development timelines. While thorough characterization is crucial for ensuring the safety and efficacy of biotherapeutics, there is a need to further streamline analytical characterization and expedite the overall timeline from discovery to market.

AREAS COVERED

This review focuses on recent developments in liquid-phase separations coupled with ion mobility-mass spectrometry (IM-MS) for the development and characterization of biotherapeutics. We cover uses of IM-MS to improve the characterization of monoclonal antibodies, antibody-drug conjugates, host cell proteins, glycans, and nucleic acids. This discussion is based on an extensive literature search using Web of Science, Google Scholar, and SciFinder.

EXPERT OPINION

IM-MS has the potential to enhance the depth and efficiency of biotherapeutic characterization by providing additional insights into conformational changes, post-translational modifications, and impurity profiles. The rapid timescale of IM-MS positions it well to enhance the information content of existing assays through its facile integration with standard liquid-phase separation techniques that are commonly used for biopharmaceutical analysis.

A robust and validated LC-MS/MS method for the quantification of ramucirumab in rat and human serum using direct enzymatic digestion without immunoassay

A new liquid chromatography tandem mass spectrometry (LC-MS/MS) method was established to quantify the anti-gastric cancer fully human monoclonal antibody (ramucirumab) in rat and human serum. The surrogate peptide (GPSVLPLAPSSK) for ramucirumab was generated by trypsin hydrolysis and quantified using the isotopically labeled peptide GPSVLPLAPSSK[13C6, 15N2]ST containing two more amino acids at the carboxyl end as an internal standard to correct for variations introduced during the enzymatic hydrolysis process and any mass spectrometry changes. Additionally, the oxidation and deamidation of unstable peptides (VVSVLTVLHQDWLNGK and NSLYLQMNSLR) were detected. The quantitative range of the proposed method was 1-1000 μg/mL, and complete methodological validation was performed. The precision, accuracy, matrix effect, sensitivity, stability, selectivity, carryover, and interference of the measurements met the required standards. The validated LC-MS/MS method was applied to pharmacokinetic studies in rats administered ramucirumab at 15 mg/kg intravenously. Overall, a robust, efficient, and cost-effective LC-MS/MS method was successfully developed for quantifying ramucirumab in rat and human serum.

Simultaneous quantification of the 22-kDa isoforms of human growth hormone 1 and 2 in human plasma by multiplexed immunocapture and LC-MS/MS

An LC-MS/MS method is presented for the simultaneous quantification of two structurally closely related protein biomarker isoforms, the 22-kDa isoforms of human growth hormone 1 and human growth hormone 2, in human plasma. It is based on multiplexed immunocapture using two monoclonal antibodies immobilized on magnetic beads, tryptic digestion and quantification of two specific signature peptides plus an additional peptide for estimation of total growth hormone related concentrations. A full validation according to international guidelines was performed across the clinically relevant concentration ranges of 0.5 to 50 ng/mL for growth hormone 1, and 2 to 50 ng/mL for growth hormone 2 and demonstrated satisfactory method performance in terms of accuracy, precision, stability and absence of interference. The method's applicability for routine analysis and its ability to effectively distinguish between GH1 and GH2 was demonstrated by the analysis of plasma samples from pregnant individuals to study the changes in growth hormone levels during pregnancy.

Absolute quantitation of binding antibodies from clinical samples

The quantitation of antibody responses is a critical requirement for the successful development of vaccines and therapeutics that often relies on the use of standardized reference materials to determine relative quantities within biological samples. The validity of comparing responses across assays using arbitrarily defined reference values is therefore limited. We developed a generalizable method known as MASCALE (Mass Spectrometry Enabled Conversion to Absolute Levels of ELISA Antibodies) for absolute quantitation of antibodies by calibrating ELISA reference sera using mass spectrometry. Levels of proteotypic peptides served as a proxy for human IgG, allowing the conversion of responses from arbitrary values to absolute amounts. Applications include comparison of binding assays at two separate laboratories and evaluation of cross-clade magnitude-breadth responses induced by an investigational HIV-1 vaccine regimen. MASCALE addresses current challenges in the interpretation of immune responses in clinical trials and expands current options available to make suitable comparisons across different settings.

An antibody-free LC-MS/MS method for the quantification of sex hormone binding globulin in human serum and plasma

OBJECTIVES

Sex hormone binding globulin (SHBG) is a hormone binding protein which plays an important role in regulating the transport and availability of biologically active androgens and estradiol to target cells and used to calculate free testosterone concentrations.

METHODS

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed, featuring an albumin removal step followed by a tryptic digestion. After a reduction step with dithiothreitol and alkylation with iodoacetamide three signature peptides were used for the quantification of SHBG.

RESULTS

The method enables the quantification of serum and plasma SHBG over the clinically relevant range of 200-20,000 ng/mL and was validated according to the most recent guidelines. The LC-MS/MS method correlates well with the Abbott Alinity immunoassay (R2>0.95), but the LC-MS/MS results are on average 16-17% lower than the immunoassay results, which is consistent for all three signature peptides.

CONCLUSIONS

The LC-MS/MS method which includes an albumin depletion step allows quantification of SHBG in serum and plasma without an immunocapture step at clinically relevant SHBG levels, thus contributing to better lab-to-lab consistency of results.

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.

Direct quantification of intact FIM in monkey plasma using a selective chromatography-tandem mass spectrometry method: Application in a pharmacokinetic study

FIM protein, which consists of 155 amino acids, was developed as a novel GLP-1 analog to reduce blood glucose, and pharmacodynamic results showed that it had a certain effect when used in treating Alzheimer's disease. The molecular weight of FIM is 16,304 Da. In theory, the concentration of FIM in biological samples should be determined by the ligand binding assay method or indirectly quantified using LC-MS/MS instrumentation. However, the above methods are complex and time-consuming. In this study, we successfully developed a simpler LC-MS/MS method for directly quantifying the intact FIM protein in monkey plasma for the first time. The chromatographic separation of FIM was achieved using an InertSustain Bio C₁₈ column with a mobile phase of acetonitrile containing 0.1% formic acid (A)-water containing 0.1% formic acid (B) at a flow rate of 0.3 ml/min. Good linearity was observed in the concentration range of 5-500 ng/ml (r²  > 0.99). The intra- and inter-day precisions (expressed as relative standard deviation, RSD) of FIM were 2.30-12.8 and 7.30-13.2%, respectively. The intra- and inter-day accuracies (expressed as a relative error, RE) were -12.7-6.55 and - 10.1-0.892%, respectively. This method was successfully applied for a pharmacokinetic study of the FIM protein in four monkeys after subcutaneous administration.

Glucose Restriction Plus Refeeding in Vitro Induce Changes of the Human Adipocyte Secretome with an Impact on Complement Factors and Cathepsins

Adipose tissue is a major endocrine organ capable of secreting adipokines with a role in whole-body metabolism. Changes in the secretome profile during the development of obesity is suspected to contribute to the risk of health complications such as those associated with weight regain after weight loss. However, the number of studies on weight regain is limited and secretome changes during weight regain have hardly been investigated. In an attempt to generate leads for in vivo studies, we have subjected human Simpson Golabi Behmel Syndrome adipocytes to glucose restriction (GR) followed by refeeding (RF) as an in vitro surrogate for weight regain after weight loss. Using LC-MS/MS, we compared the secreted protein profile after GR plus RF with that of normal feeding (NF) to assess the consequences of GR plus RF. We identified 338 secreted proteins of which 49 were described for the first time as being secreted by adipocytes. In addition, comparison between NF and GR plus RF showed 39 differentially secreted proteins. Functional classification revealed GR plus RF-induced changes of enzymes for extracellular matrix modification, complement system factors, cathepsins, and several proteins related to Alzheimer’s disease. These observations can be used as clues to investigate metabolic consequences of weight regain, weight cycling or intermittent fasting.

Improving selectivity and sensitivity of protein quantitation by LC–HR–MS/MS: determination of somatropin in rat plasma

Aim: Protein quantitation by digestion of a biological sample followed by LC–MS analysis of a signature peptide can be a challenge because of the high complexity of the digested matrix. Results/methodology: The use of LC with high-resolution (quadrupole-TOF) MS detection allowed quantitation of the 22-kDa biopharmaceutical somatropin in 60 μl of rat plasma down to 25 ng/ml with minimal further sample treatment. Reducing the mass extraction window to 0.01 Da considerably decreased the interference of tryptic peptides, enhanced sensitivity and improved accuracy and precision. Analysis with LC–MS/MS resulted in a less favorable limit of quantitation of 100 ng/ml. Conclusion: HRMS is an interesting option for the quantitation of proteins after digestion and has the potential to improve sensitivity with minimal method development.

High Mobility Group Box-1 (HMGb1): Current Wisdom and Advancement as a Potential Drug Target

High mobility group box-1 (HMGb1) protein, a nuclear non-histone protein that is released or secreted from the cell in response to damage or stress, is a sentinel for the immune system that plays a critical role in cell survival/death pathways. This review highlights key features of the endogenous danger-associated molecular pattern (DAMP) protein, HMGb1 in the innate inflammatory response along with various cofactors and receptors that regulate its downstream effects. The evidence demonstrating increased levels of HMGb1 in human inflammatory diseases and conditions is presented, along with a summary of current small molecule or peptide-like antagonists proven to specifically target HMGb1. Additionally, we delineate the measures needed toward validating this protein as a clinically relevant biomarker or bioindicator and as a relevant drug target.

Qualitative and quantitative characterization of protein biotherapeutics with liquid chromatography mass spectrometry

In the last decade, the advancement of liquid chromatography mass spectrometry (LC/MS) techniques has enabled their broad application in protein characterization, both quantitatively and qualitatively. Owing to certain important merits of LC/MS techniques (e.g., high selectivity, flexibility, and rapid method development), LC/MS assays are often deemed as preferable alternatives to conventional methods (e.g., ligand-binding assays) for the analysis of protein biotherapeutics. At the discovery and development stages, LC/MS is generally employed for two purposes absolute quantification of protein biotherapeutics in biological samples and qualitative characterization of proteins. For absolute quantification of a target protein in bio-matrices, recent work has led to improvements in the efficiency of LC/MS method development, sample treatment, enrichment and digestion, and high-performance low-flow-LC separation. These advances have enhanced analytical sensitivity, specificity, and robustness. As to qualitative analysis, a range of techniques have been developed to characterize intramolecular disulfide bonds, glycosylation, charge variants, primary sequence heterogeneity, and the drug-to-antibody ratio of antibody drug conjugate (ADC), which has enabled a refined ability to assess product quality. In this review, we will focus on the discussion of technical challenges and strategies of LC/MS-based quantification and characterization of biotherapeutics, with the emphasis on the analysis of antibody-based biotherapeutics such as monoclonal antibodies (mAbs) and ADCs. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:734-754, 2017.

Immunoaffinity techniques coupled to mass spectrometry for the analysis of human peptide hormones: advances and applications

INTRODUCTION

The accurate and comprehensive determination of peptide hormones from biological fluids has represented a considerable challenge to analytical chemists for decades. Besides long-established bioanalytical ligand binding assays (or ELISA, RIA, etc.), more and more mass spectrometry-based methods have been developed recently for purposes commonly referred to as targeted proteomics. Eventually the combination of both, analyte extraction by immunoaffinity and subsequent detection by mass spectrometry, has shown to synergistically enhance the test methods' performance characteristics. Areas covered: The review provides an overview about the actual state of existing methods and applications concerning the analysis of endogenous peptide hormones. Here, special focus is on recent developments considering the extraction procedures with immobilized antibodies, the subsequent separation of target analytes, and their detection by mass spectrometry. Expert commentary: Key aspects of procedures aiming at the detection and/or quantification of peptidic analytes in biological matrices have experienced considerable improvements in the last decade, particularly in terms of the assays' sensitivity, the option of multiplexing target compounds, automatization, and high throughput operation. Despite these advances and progress as expected to be seen in the near future, immunoaffinity purification coupled to mass spectrometry is not yet a standard procedure in routine analysis compared to ELISA/RIA.

Applications of Raman Spectroscopy in Biopharmaceutical Manufacturing: A Short Review

The production of active pharmaceutical ingredients (APIs) is currently undergoing its biggest transformation in a century. The changes are based on the rapid and dramatic introduction of protein- and macromolecule-based drugs (collectively known as biopharmaceuticals) and can be traced back to the huge investment in biomedical science (in particular in genomics and proteomics) that has been ongoing since the 1970s. Biopharmaceuticals (or biologics) are manufactured using biological-expression systems (such as mammalian, bacterial, insect cells, etc.) and have spawned a large (>€35 billion sales annually in Europe) and growing biopharmaceutical industry (BioPharma). The structural and chemical complexity of biologics, combined with the intricacy of cell-based manufacturing, imposes a huge analytical burden to correctly characterize and quantify both processes (upstream) and products (downstream). In small molecule manufacturing, advances in analytical and computational methods have been extensively exploited to generate process analytical technologies (PAT) that are now used for routine process control, leading to more efficient processes and safer medicines. In the analytical domain, biologic manufacturing is considerably behind and there is both a huge scope and need to produce relevant PAT tools with which to better control processes, and better characterize product macromolecules. Raman spectroscopy, a vibrational spectroscopy with a number of useful properties (nondestructive, non-contact, robustness) has significant potential advantages in BioPharma. Key among them are intrinsically high molecular specificity, the ability to measure in water, the requirement for minimal (or no) sample pre-treatment, the flexibility of sampling configurations, and suitability for automation. Here, we review and discuss a representative selection of the more important Raman applications in BioPharma (with particular emphasis on mammalian cell culture). The review shows that the properties of Raman have been successfully exploited to deliver unique and useful analytical solutions, particularly for online process monitoring. However, it also shows that its inherent susceptibility to fluorescence interference and the weakness of the Raman effect mean that it can never be a panacea. In particular, Raman-based methods are intrinsically limited by the chemical complexity and wide analyte-concentration-profiles of cell culture media/bioprocessing broths which limit their use for quantitative analysis. Nevertheless, with appropriate foreknowledge of these limitations and good experimental design, robust analytical methods can be produced. In addition, new technological developments such as time-resolved detectors, advanced lasers, and plasmonics offer potential of new Raman-based methods to resolve existing limitations and/or provide new analytical insights.

Infliximab quantitation in human plasma by liquid chromatography-tandem mass spectrometry: towards a standardization of the methods?

Infliximab (IFX) is a chimeric monoclonal antibody targeting tumor necrosis factor-alpha. It is currently approved for the treatment of certain rheumatic diseases or inflammatory bowel diseases. Clinical studies have suggested that monitoring IFX concentrations could improve treatment response. However, in most studies, IFX was quantified using ELISA assays, the resulting discrepancies of which raised concerns about their reliability. Here, we describe the development and validation of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for IFX quantification in human plasma. Full-length stable-isotope-labeled antibody (SIL-IFX) was added to plasma samples as internal standard. Samples were then prepared using Mass Spectrometry Immuno Assay (MSIA™) followed by trypsin digestion and submitted to multiple reaction monitoring (MRM) for quantification of IFX. The chromatographic run lasted 13 min. The range of quantification was 1 to 26 mg/L. For two internal quality controls spiked with 6 and 12 mg/L of IFX, the method was reproducible (coefficients of variation (CV%): 12.7 and 2.1), repeatable (intra-day CV%: 5.5 and 5.0), and accurate (inter-day and intra-day deviations from nominal values: +6.4 to +3.7 % and 5.5 to 9.2 %, respectively). There was no cross - contamination effect. Samples from 45 patients treated with IFX were retrospectively analyzed by LC-MS/MS and results were compared to those obtained with an in-house ELISA assay and the commercial Lisa Tracker® method. Good agreement was found between LC-MS/MS and in-house ELISA (mean underestimation of 13 % for in-house ELISA), but a significant bias was found with commercial ELISA (mean underestimation of 136 % for commercial ELISA). This method will make it possible to standardize IFX quantification between laboratories. Graphical Abstract Interassay comparison of the three methods: LC-MS/MS vs inhouse ELISA assay or vs Lisa Tracker® ELISA assays, Passing & Bablok (a) and Bland & Altman (b) for the comparison of LC-MS/MS vs in-house ELISA assay; Passing & Bablok

Challenges for the in vivo quantification of brain neuropeptides using microdialysis sampling and LC-MS

In recent years, neuropeptides and their receptors have received an increased interest in neuropharmacological research. Although these molecules are considered relatively small compared with proteins, their in vivo quantification using microdialysis is more challenging than for small molecules. Low microdialysis recoveries, aspecific adsorption and the presence of various multiply charged precursor ions during ESI-MS/MS detection hampers the in vivo quantification of these low abundant biomolecules. Every step in the workflow, from sampling until analysis, has to be optimized to enable the sensitive analysis of these compounds in microdialysates.

Reduction of dilution error in ELISAs using an internal standard

Background: Dilution bias is a major cause of immunoassay variability due to the lack of an internal standard to determine the true versus the expected dilution value. Methodology: We used an internal control to measure dilution bias in an ELISA. Acridine-orange was added at the first dilution step and monitored throughout dilutions. Assay results were corrected using the fluorescent signal ratio between samples and reference. Acridine dilution correlated with analyte-specific assay measurements (R2 = 0.987). Correction of assay results with the measured dilution factor improved both accuracy and precision resulting in a reduction of >50% %CV reduction. Conclusion: Dilution correction can significantly improve accuracy and precision of immunoassays. Additional control strategies may further mitigate other sources of variability.

Highly sensitive antibody-free μLC–MS/MS quantification of rhTRAIL in serum

Background: We describe an antibody-free approach to quantify rhTRAILWT (wild-type) and its closely related death receptor 4 selective variant rhTRAIL4C7 in human and murine serum by multiplex LC–MS/MS on a microfluidics interface. Methodology: Enrichment of rhTRAIL was performed by strong cation-exchange (SCX) followed by immobilized metal affinity (IMAC) solid-phase extraction. This was followed by trypsin digestion and using methionine-containing signature peptides after fully oxidizing the methionine residue with 0.25% (w/w) hydrogen peroxide. Conclusion: Absolute quantification was reaching down to 0.5 ng/ml for rhTRAILWT (8.5 pM) and 2 ng/ml for rhTRAIL4C7 (34 pM) in 100 μl human serum. To support preclinical studies in mice, the analysis was optimized further, for a sample volume of 20 μl murine serum.

Thermal-assisted gasification injector for analyzing high-salt solution samples: a novel device developed for online coupling of liquid chromatography with direct analysis in real time mass spectrometry

A thermal-assisted gasification injector was designed for online coupling of liquid-chromatography to direct-analysis-in-real-time mass-spectrometry. The method can be used in analysis with an inorganic salt matrix and weak polar solvent.

Solvent interaction analysis as a proteomic approach to structure-based biomarker discovery and clinical diagnostics

Proteins have several measurable features in biological fluids that may change under pathological conditions. The current disease biomarker discovery is mostly based on protein concentration in the sample as the measurable feature. Changes in protein structures, such as post-translational modifications and in protein-partner interactions are known to accompany pathological processes. Changes in glycosylation profiles are well-established for many plasma proteins in various types of cancer and other diseases. The solvent interaction analysis method is based on protein partitioning in aqueous two-phase systems and is highly sensitive to changes in protein structure and protein-protein- and protein-partner interactions while independent of the protein concentration in the biological sample. It provides quantitative index: partition coefficient representing changes in protein structure and interactions with partners. The fundamentals of the method are presented with multiple examples of applications of the method to discover and monitor structural protein biomarkers as disease-specific diagnostic indicators.