Clonotypic Light Chain Peptides Identified for Monitoring Minimal Residual Disease in Multiple Myeloma without Bone Marrow Aspiration

Using Mass Spectrometry to Quantify Rituximab and Perform Individualized Immunoglobulin Phenotyping in ANCA-Associated Vasculitis

Therapeutic monoclonal immunoglobulins (mAbs) are used to treat patients with a wide range of disorders including autoimmune diseases. As pharmaceutical companies bring more fully humanized therapeutic mAb drugs to the healthcare market analytical platforms that perform therapeutic drug monitoring (TDM) without relying on mAb specific reagents will be needed. In this study we demonstrate that liquid-chromatography-mass spectrometry (LC-MS) can be used to perform TDM of mAbs in the same manner as smaller nonbiologic drugs. The assay uses commercially available reagents combined with heavy and light chain disulfide bond reduction followed by light chain analysis by microflow-LC-electrospray ionization-quadrupole-time-of-flight mass spectrometry (ESI-Q-TOF MS). Quantification is performed using the peak areas from multiply charged mAb light chain ions using an in-house developed software package developed for TDM of mAbs. The data presented here demonstrate the ability of an LC-MS assay to quantify a therapeutic mAb in a large cohort of patients in a clinical trial. The ability to quantify any mAb in serum via the reduced light chain without the need for reagents specific for each mAb demonstrates the unique capabilities of LC-MS. This fact, coupled with the ability to phenotype a patient's polyclonal repertoire in the same analysis further shows the potential of this approach to mAb analysis.

Systemic amyloidoses and proteomics: The state of the art

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Proteomics is an established approach for diagnostic amyloid typing.

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Mass spectrometry-based methods to analyze amyloid precursors have been developed.

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Proteomic studies are ongoing to identify novel biomarkers and clarify disease mechanisms.

Systemic amyloidoses are caused by misfolding-prone proteins that polymerize in tissues, causing organ dysfunction. Since proteins are etiological agents of these diseases, proteomics was soon recognized as a privileged instrument for their investigation. Mass spectrometry-based proteomics has acquired a fundamental role in management of systemic amyloidoses, being now considered a gold standard approach for amyloid typing. In parallel, approaches for analyzing circulating amyloid precursors have been developed. Moreover, differential and functional proteomics hold promise for identifying novel biomarkers and clarifying disease mechanisms. This review discusses recent proteomics achievements in systemic amyloidoses, providing a perspective on its present and future applications.