mAbs Testing in Inflammation Using Mass Spectrometry – Combination of mAbXmise™ Kits and XEVO™ TQ Absolute XR Mass Spectrometer

Importance of Topic

Monoclonal antibodies (mAbs) have transformed the management of inflammatory bowel disease by offering targeted therapies. Consistent monitoring of drug levels and anti-drug antibodies is critical to optimize treatment, avoid loss of response, and guide dose adjustments. Liquid chromatography–tandem mass spectrometry (LC-MS/MS) addresses limitations of immunoassays by providing peptide-level specificity, broad dynamic range, multiplex capacity, and robust internal standard correction.

Objectives and Study Overview

This application note describes a streamlined, clinically implementable workflow for quantitative monitoring of four inflammation mAbs (infliximab, adalimumab, ustekinumab, vedolizumab) and two anti-drug antibodies. The study combines ready-to-use sample preparation kits (mAbXmise ITDM2 and IADA1) with optimized LC-MS/MS methods on a Waters Xevo TQ Absolute XR instrument to demonstrate sensitivity, linearity, precision, and concordance with immunoassays.

Methodology

Sample preparation employs protease-based digestion using mAbXmise kits: ITDM2 for mAb quantification from 10 µL serum and IADA1 for anti-drug antibodies from 100 µL. Digestion occurs at 37 °C overnight. Chromatography is performed on an ACQUITY Premier Peptide CSH C18 column (100×2.1 mm, 1.7 µm) with an 8-minute gradient using 0.1% formic acid in water (A) and acetonitrile (B). Mass spectrometry uses MRM transitions in positive ESI mode, with capillary voltage 1.0 kV, desolvation at 650 °C, and 1100 L/h gas flow.

Instrumentation

• Xevo TQ Absolute XR Tandem Quadrupole Mass Spectrometer
• ACQUITY Premier UPLC System with FTN injector, binary pump, column manager
• ACQUITY Premier Peptide CSH C18 column, 130 Å, 1.7 µm, 2.1×100 mm
• MassLynx Software v4.2

Main Results and Discussion

Calibration for mAb peptides was linear from 0.5 to 100 µg/mL (r²>0.99) with LOQs meeting kit specifications. Precision across QC levels showed RSD<10% and accuracy within 94-114%. Anti-drug antibody assays were quadratic over 10–400 ng/mL with RSD<10% and accuracy 90-106%. Patient sample analysis (n=7) correlated well with immunoassays for drug levels and anti-drug antibody presence, demonstrating method reliability and clinical concordance.

Benefits and Practical Applications

• High specificity reduces false positives/negatives compared to immunoassays
• Multiplex capability allows simultaneous quantification of multiple biologics
• Wide dynamic range covers sub-therapeutic to high concentrations
• Internal standards correct for matrix and operational variability
• Rapid implementation using ready-to-use kits in clinical labs

Future Trends and Applications

Adoption of LC-MS/MS platforms for routine therapeutic drug monitoring will expand with further automation of sample prep, inclusion of additional biologics, integration with laboratory information systems, and development of universal peptide panels for broader immunogenicity assessment.

Conclusion

The combined mAbXmise kits and Xevo TQ Absolute XR workflow delivers a sensitive, precise, and robust solution for monitoring inflammation mAbs and anti-drug antibodies. This LC-MS/MS approach supports clinical decision-making, offers improved standardization over immunoassays, and is readily deployable in diagnostic laboratories.

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