Distinguishing Daratumumab from Endogenous Monoclonal Proteins in Serum from Multiple Myeloma Patients Using an Automated Mass Spectrometry System.

Background: Therapeutic monoclonal antibodies (t-mAbs) may interfere with electrophoresis-based methods used to monitor multiple myeloma (MM), which can create inaccurate results. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is an alternative to gels distinguishing between endogenous M-proteins and t-mAbs based on molecular mass.

Methods: Serum samples (n = 109) from 34 MM patients receiving Dara-KRd were collected 14 or 28 days postdaratumumab administration.

Final analysis of a phase II trial of daratumumab, carfilzomib, lenalidomide, and dexamethasone in newly diagnosed multiple myeloma without transplant.

We evaluated the efficacy and safety of 24 cycles of Dara in combination with carfilzomib (K), lenalidomide (R), and dexamethasone (d) without autologous stem cell transplant (ASCT) in newly diagnosed multiple myeloma (NDMM) irrespective of ASCT eligibility in a single-arm, phase II study. The primary endpoint was the rate of stringent complete response (sCR) and/or measurable residual disease (MRD) < 10 by next-generation sequencing (NGS) at the end of cycle 8 (C8). MRD was also assessed on peripheral blood samples using both the EXENT system and liquid chromatography-mass spectrometry (LC-MS).

Mass spectrometry-based assessment of M protein in peripheral blood during maintenance therapy in multiple myeloma.

Mass spectrometry (MS) can detect multiple myeloma-derived monoclonal proteins in the peripheral blood (PB) with high sensitivity, potentially serving as a PB assay for measurable residual disease (MRD). This study evaluated the significance of PB MS MRD negativity during posttransplant therapy in patients with newly diagnosed multiple myeloma. Serum samples from 138 patients treated in the phase 3 ATLAS trial of posttransplant maintenance with either carfilzomib, lenalidomide, and dexamethasone, or with lenalidomide alone were analyzed using EXENT MS methodology.

Endogenous monoclonal immunoglobulins analyzed using the EXENT® solution and LC-MS.

Introduction: The EXENT® Solution, a fully automated system, is a recent advancement for identifying and quantifying monoclonal immunoglobulins in serum. It combines immunoprecipitation with MALDI-TOF mass spectrometry. Compared to gel-based methods, like SPEP and IFE, it has demonstrated the ability to detect monoclonal immunoglobulins in serum at lower levels.

Mass spectrometry-detected MGUS is associated with obesity and other novel modifiable risk factors in a high-risk population.

Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant condition of multiple myeloma with few known risk factors. The emergence of mass spectrometry (MS) for the detection of MGUS has provided new opportunities to evaluate its risk factors. In total, 2628 individuals at elevated risk for multiple myeloma were enrolled in a screening study and completed an exposure survey (PROMISE trial).

Analysis of monoclonal immunoglobulins from bone marrow plasma cells using immunopurification and LC-MS.

Introduction: Clonal plasma cells secrete immunoglobulins, each with the exact same amino acid sequence, that are referred to as monoclonal immunoglobulins. The monoclonal heavy chain and light chain secreted from clonal plasma cells have the same molecular mass prior to the addition of post-translational modifications (PTMs) since their amino acid sequences are the same.

Objective: To examine the molecular masses of monoclonal light chains and heavy chains isolated directly from the cytoplasm of bone marrow (BM) plasma cells and compare them to the serum derived monoclonal heavy and light chains.

Development of novel methods for non-canonical myeloma protein analysis with an innovative adaptation of immunofixation electrophoresis, native top-down mass spectrometry, and middle-down sequencing.

Objectives: Multiple myeloma (MM) is a malignant plasma cell neoplasm, requiring the integration of clinical examination, laboratory and radiological investigations for diagnosis. Detection and isotypic identification of the monoclonal protein(s) and measurement of other relevant biomarkers in serum and urine are pivotal analyses. However, occasionally this approach fails to characterize complex protein signatures.

Correction: Assay to rapidly screen for immunoglobulin light chain glycosylation: a potential path to earlier AL diagnosis for a subset of patients.

Following the publication of this article, the authors noted that Patrick M. Vanderboom was inadvertently omitted from the author list. The correct author list is as follows: Sanjay Kumar, David Murray, Surendra Dasari, Paolo Milani, David Barnidge, Benjamin Madden, Patrick M.

Classification of Plasma Cell Disorders by 21 Tesla Fourier Transform Ion Cyclotron Resonance Top-Down and Middle-Down MS/MS Analysis of Monoclonal Immunoglobulin Light Chains in Human Serum.

The current five-year survival rate for systemic AL amyloidosis or multiple myeloma is ∼51%, indicating the urgent need for better diagnosis methods and treatment plans. Here, we describe highly specific and sensitive top-down and middle-down MS/MS methods owning the advantages of fast sample preparation, ultrahigh mass accuracy, and extensive residue cleavages with 21 telsa FT-ICR MS/MS. Unlike genomic testing, which requires bone marrow aspiration and may fail to identify all monoclonal immunoglobulins produced by the body, the present method requires only a blood draw.

Pharmacokinetics of rituximab and clinical outcomes in patients with anti-neutrophil cytoplasmic antibody associated vasculitis.

Objectives: To study the determinants of the pharmacokinetics (PK) of rituximab (RTX) in patients with ANCA-associated vasculitis (AAV) and its association with clinical outcomes.

Methods: This study included data from 89 patients from the RTX in AAV trial who received the full dose of RTX (four weekly infusions of 375 mg/m2). RTX was quantified at weeks 2, 4, 8, 16 and 24, and summarized by computing the trapezoidal area under the curve.

The utility of MASS-FIX to detect and monitor monoclonal proteins in the clinic.

The detection and quantification of monoclonal-proteins (M-proteins) are necessary for the diagnosis and evaluation of response in plasma cell dyscrasias. Immunoglobulin enrichment-coupled with matrix-assisted laser desorption ionization time-of-flight mass-spectrometry (MASS-FIX) is a simple and inexpensive method to identify M-proteins, but its clinical generalizability has not yet been elucidated. We compared MASS-FIX to protein electrophoresis (PEL), serum/urine immunofixation-electrophoresis (IFE), and quantitative serum free-light chain (FLC) for the identification of M-proteins in different clinical diagnoses.

Assessment of renal response with urinary exosomes in patients with AL amyloidosis: A proof of concept.

Immunoglobulin light chain (AL) amyloidosis is a fatal complication of B-cell proliferation secondary to deposition of amyloid fibrils in various organs. Urinary exosomes (UEX) are the smallest of the microvesicles excreted in the urine. Previously, we found UEX of patients with AL amyloidosis contained immunoglobulin light chain (LC) oligomers that patients with multiple myeloma did not have.

Mass Spectrometry Approaches for Identification and Quantitation of Therapeutic Monoclonal Antibodies in the Clinical Laboratory.

Therapeutic monoclonal antibodies (MAbs) are an important class of drugs used to treat diseases ranging from autoimmune disorders to B cell lymphomas to other rare conditions thought to be untreatable in the past. Many advances have been made in the characterization of immunoglobulins as a result of pharmaceutical companies investing in technologies that allow them to better understand MAbs during the development phase. Mass spectrometry is one of the new advancements utilized extensively by pharma to analyze MAbs and is now beginning to be applied in the clinical laboratory setting.

Analysis of Monoclonal Antibodies in Human Serum as a Model for Clinical Monoclonal Gammopathy by Use of 21 Tesla FT-ICR Top-Down and Middle-Down MS/MS.

With the rapid growth of therapeutic monoclonal antibodies (mAbs), stringent quality control is needed to ensure clinical safety and efficacy. Monoclonal antibody primary sequence and post-translational modifications (PTM) are conventionally analyzed with labor-intensive, bottom-up tandem mass spectrometry (MS/MS), which is limited by incomplete peptide sequence coverage and introduction of artifacts during the lengthy analysis procedure. Here, we describe top-down and middle-down approaches with the advantages of fast sample preparation with minimal artifacts, ultrahigh mass accuracy, and extensive residue cleavages by use of 21 tesla FT-ICR MS/MS.

Quantification of the IgG2/4 kappa Monoclonal Therapeutic Eculizumab from Serum Using Isotype Specific Affinity Purification and Microflow LC-ESI-Q-TOF Mass Spectrometry.

As therapeutic monoclonal antibodies (mAbs) become more humanized, traditional tryptic peptide approaches used to measure biologics in serum become more challenging since unique clonotypic peptides used for quantifying the mAb may also be found in the normal serum polyclonal background. An alternative approach is to monitor the unique molecular mass of the intact light chain portion of the mAbs using liquid chromatography-mass spectrometry (LC-MS). Distinguishing a therapeutic mAb from a patient's normal polyclonal immunoglobulin (Ig) repertoire is the primary limiting factor when determining the limit of quantitation (LOQ) in serum.

Comprehensive Assessment of M-Proteins Using Nanobody Enrichment Coupled to MALDI-TOF Mass Spectrometry.

Background: Electrophoretic separation of serum and urine proteins has played a central role in diagnosing and monitoring plasma cell disorders. Despite limitations in resolution and analytical sensitivity, plus the necessity for adjunct methods, protein gel electrophoresis and immunofixation electrophoresis (IFE) remain front-line tests.

Methods: We developed a MALDI mass spectrometry-based assay that was simple to perform, automatable, analytically sensitive, and applicable to analyzing the wide variety of monoclonal proteins (M-proteins) encountered clinically.

Screening Method for M-Proteins in Serum Using Nanobody Enrichment Coupled to MALDI-TOF Mass Spectrometry.

Background: Current recommendations for screening for monoclonal gammopathies include serum protein electrophoresis (PEL), imunofixation electrophoresis (IFE), and free light chain (FLC) ratios to identify or rule out an M-protein. The aim of this study was to examine the feasibility of an assay based on immunoenrichment and MALDI-TOF-MS (MASS-SCREEN) to qualitatively screen for M-proteins.

Methods: Serum from 556 patients previously screened for M-proteins by PEL and IFE were immunopurified using a κ/λ-specific nanobody bead mixture.

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.

Laboratory testing in monoclonal gammopathy of renal significance (MGRS).

Recently, monoclonal gammopathy of renal significance (MGRS) reclassified all monoclonal (M) gammopathies that are associated with the development of a kidney disease but do not meet the definition of symptomatic multiple myeloma (MM) or malignant lymphoma. The purpose was to distinguish the M gammopathy as the nephrotoxic agent independent from the clonal mass. The diagnosis of MGRS obviously depends on the detection of the M-protein.

Monitoring free light chains in serum using mass spectrometry.

Background: Serum immunoglobulin free light chains (FLC) are secreted into circulation by plasma cells as a by-product of immunoglobulin production. In a healthy individual the population of FLC is polyclonal as no single cell is secreting more FLC than the total immunoglobulin secreting cell population. In a person with a plasma cell dyscrasia, such as multiple myeloma (MM) or light chain amyloidosis (AL), a clonal population of plasma cells secretes a monoclonal light chain at a concentration above the normal polyclonal background.