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

Quantification of the lung cancer tumor marker CYFRA 21-1 using protein precipitation, immunoaffinity bottom-up LC-MS/MS

OBJECTIVES

Numerous studies have proven the potential of cytokeratin 19 fragment 21-1 (CYFRA 21-1) detection in the (early) diagnosis and treatment monitoring of non-small cell lung cancer (NSCLC). Conventional immunoassays for CYFRA 21-1 quantification are however prone to interferences and lack diagnostic sensitivity and standardization. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is an emerging approach based on a different, often superior, detection principle, which may improve the clinical applicability of CYFRA 21-1 in cancer diagnostics. Therefore, we developed and validated a protein precipitation, immunoaffinity (IA) LC-MS/MS assay for quantitative analysis of serum CYFRA 21-1.

METHODS

Selective sample preparation was performed using ammonium sulfate (AS) precipitation, IA purification, tryptic digestion and LC-MS/MS quantification using a signature peptide and isotopically labeled internal standard. The workflow was optimized and validated according to EMA guidelines and results were compared to a conventional immunoassay.

RESULTS

Significant interference effects were seen during IA purification, which were sufficiently solved by performing AS precipitation prior to IA purification. A linear calibration curve was obtained in the range of 1.0-100 ng/mL (R2=0.98). Accuracy and precision were well within acceptance criteria. In sera of patients suspected of lung cancer, the method showed good correlation with the immunoassay.

CONCLUSIONS

A robust AS precipitation-IA LC-MS/MS assay for the quantification of serum CYFRA 21-1 was developed. With this assay, the clinically added value of LC-MS/MS-based detection over immunoassays can be further explored.

DosEmi study protocol: a phase IV, multicentre, open-label, crossover study to evaluate non-inferiority of pharmacokinetic-guided reduced dosing compared with conventional dosing of emicizumab in people with haemophilia A

INTRODUCTION

Emicizumab effectively prevents bleeding in people with haemophilia A (PwHA), but is a burden for national healthcare budgets and consequently may limit access. According to the drug label, dosing of emicizumab is based on body weight with fixed intervals of 7, 14 or 28 days, which leads to mean plasma concentrations of 55 µg/mL (SD 15 µg/mL). However, a moderate variability of concentrations and a minimal effective concentration of 30 µg/mL have been suggested in studies. Therefore, a dose of emicizumab that targets a trough concentration of 30 µg/mL is hypothesised to be equally effective as conventional dosing in the prevention of bleeding.

METHODS AND ANALYSIS

We designed a phase IV, multicentre, open-label, crossover study to evaluate non-inferiority of bleed control of ≥6 months on conventional dosing in comparison to ≥6 months on dose intervention. This dose intervention consists of reducing the dose of emicizumab to target a trough concentrations of 30 µg/mL using individual pharmacokinetic (PK) parameters. Ninety-five PwHA aged >1 years who received conventional dosing of emicizumab for ≥12 months with good bleeding control during the last 6 months will be recruited from all Dutch haemophilia treatment centres. The study is powered to detect a clinically relevant decrease (risk difference) of 15% in the proportion of patients without treated bleeds during follow-up. Secondary endpoints are spontaneous joint or muscle bleeds, and annualised treated bleeding rates (using negative binomial regression). Cost-effectivity between conventional dosing and individualised PK-guided dosing of emicizumab will be compared.

ETHICS AND DISSEMINATION

The DosEmi study was approved by the Medical Ethics Review Committee NedMec of the University Medical Center of Utrecht, The Netherlands. Study results will be communicated through publications in international scientific journals and presentations at (inter)national conferences.

TRIAL REGISTRATION NUMBER

EUCTR2021-004039-10-NL at https://trialsearch.who.int.

PROTOCOL VERSION

V.4.1 on 28 October 2022 (DosEmi protocol_V4.1; NL81112.041.22).

The efficacy of the entire-vial dosing of emicizumab: Real-world evidence on plasma concentrations, bleeds, and drug waste

Background

Prophylaxis with emicizumab provides effective bleeding protection in persons with hemophilia A (PwHA) but pressures healthcare budgets. The body weight-adjusted dosing at 7-, 14-, or 28-day intervals, according to the label, often mismatches the vial content. Entire-vial dosing resulted in therapeutic concentrations according to pharmacokinetic simulations and was introduced to avoid waste.

Objectives

The objective of this study was to evaluate the efficacy of entire-vial dosing of emicizumab by investigating real-world evidence of plasma concentrations, bleeds, and drug waste.

Methods

This is a single-center, observational study with PwHA receiving emicizumab in mg/kg doses according to label but dosing interval extrapolated to the nearest vial size. Patient characteristics and bleeds were compared 1 year before starting emicizumab and during emicizumab until January 2022. Concentrations were assessed at weeks 4, 12, and annually. The mean (95% CI) annualized bleed rates were compared by using negative binomial regression. Drug waste between label-based dosing and entire-vial dosing was compared.

Results

A total of 112 individuals (94% severe phenotype and 9% positive FVIII inhibitors) were followed for a median of 56 weeks (interquartile range [IQR] 52-68) before and 51 weeks (IQR 29-75) after starting emicizumab. The median emicizumab dose was 5.9 (IQR 5.5-6.2) mg/kg/4 wk with median concentrations of 63 (IQR 51-80) μg/mL. The annualized bleed rate of treated bleeds before emicizumab was 3.6 (95% CI 2.9-4.4) and was 0.8 (95% CI 0.6-1.1) during emicizumab (P < .001). Drug waste was reduced by 9%.

Conclusion

The entire-vial dosing of emicizumab is an attractive treatment option for PwHA leading to therapeutic plasma concentrations, good bleeding control, and drug waste avoidance.

High dupilumab levels in tear fluid of atopic dermatitis patients with moderate-to-severe ocular surface disease

BACKGROUND

The patho-mechanism of ocular surface disease (OSD) in dupilumab-treated atopic dermatitis (AD) patients remains unclear. The aim of this study is to measure dupilumab levels in tear fluid and serum, and relate these findings to the severity of OSD during dupilumab treatment in AD patients.

METHODS

This prospective study included dupilumab-treated moderate-to-severe AD patients who were seen by a dermatologist and an ophthalmologist before the start of dupilumab (baseline), and after 4 and 28 weeks of dupilumab treatment. Dupilumab levels in tear fluid and serum were measured by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Additionally, a pilot study was conducted to measure dupilumab on conjunctival epithelial cells using flow cytometry and LC-MS/MS.

RESULTS

At baseline, 89.6% (n = 43/48) of the patients had OSD, with 50.0% having moderate-to-severe OSD. After 28 weeks of dupilumab treatment, the median dupilumab tear fluid levels were 0.55 mg/L (IQR 0.35-1.31) and 0.29 mg/L (IQR 0.16-0.60) in patients with moderate-to-severe OSD and patients with no or mild OSD, respectively (p = 0.02). Dupilumab levels could be detected on conjunctival epithelial cells of 5 AD patients treated with dupilumab for 4 weeks.

CONCLUSION

Patients with moderate-to-severe OSD had higher dupilumab tear fluid levels compared to patients with no or mild OSD, indicating that dupilumab reaches the ocular surface. Dupilumab was also detected in conjunctival cell suspensions and was found to directly bind CD45-conjunctival epithelial cells. This suggests that AD-induced changes of the conjunctival epithelium may play a role in the development of OSD as well as increased local drug availability.

Quantification of canakinumab in human plasma by liquid chromatography-high resolution mass spectrometry

Canakinumab is a fully-human monoclonal immunoglobulin gamma 1 kappa. This interleukin-1β blocker is used for the treatment of autoinflammatory diseases. Various studies have demonstrated the value of therapeutic drug monitoring of monoclonal antibodies in the management of inflammatory diseases. The purpose of this study was to develop a method to quantify canakinumab plasmatic concentration using liquid chromatography-high-resolution (Orbitrap®) mass spectrometry. The quantification was based on a bottom-up approach with the analysis of one surrogate peptide after an immunopurification of IgG followed by tryptic proteolysis. Rituximab and cetuximab, both IgG1, were tested as internal standards. Chromatographic separation was performed on a bioZenTM Peptide PS-C18 column. Mass detection was conducted in positive ionization mode with Parallel Reaction Monitoring at a resolution of 70,000. The method was fully validated in terms of linearity, sensitivity, selectivity, accuracy and matrix effect. Standards ranged from 2.5 to 75 µg/mL. Intra- and inter-day coefficients of variation ranged from 3.7 to 14.7 %, and accuracy from 97.4 to 104.1 %. This method allowed the determination of canakinumab plasmatic concentrations from eight treated patients. This method is efficient and suitable for routine use in therapeutic drug monitoring or pharmacokinetic studies.

Quantification of emicizumab by mass spectrometry in plasma of people with hemophilia A: A method validation study

Background

Emicizumab is a new treatment option for people with hemophilia A. Emicizumab was approved with a body‐weight‐based dosage regimen, without laboratory monitoring requirements. Guidelines, however, recommend measuring emicizumab concentrations when the presence of antidrug antibodies is suspected. Furthermore, drug monitoring can be useful in clinical decision making, in adherence checking, and for research purposes. Therefore, we developed a liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method for quantifying emicizumab. We performed a validation study on this LC‐MS/MS method quantifying emicizumab in the plasma of people with hemophilia A.

Methods

Sample preparation for LC‐MS/MS analysis included ammonium sulfate protein precipitation and trypsin digestion. A signature peptide of emicizumab and a matching stable isotope‐labeled internal standard were used to quantify emicizumab by LC‐MS/MS analysis. Validation was performed in accordance with the “Guideline on Bioanalytical Method Validation” of the European Medicines Agency (EMA). The LC‐MS/MS method was cross validated against a modified and calibrated (r² Diagnostics) one‐stage clotting assay (OSA).

Conclusions

The LC‐MS/MS method demonstrated linearity over a wide range of emicizumab concentrations, far exceeding the concentrations observed in people with hemophilia A. Precision and accuracy were excellent, and all other validation parameters were also within the acceptance EMA criteria. Cross validation showed that the LC‐MS/MS method and the OSA‐based method can be used interchangeably for drug monitoring of emicizumab without the application of a correction factor.