BACKGROUND: Immunofixation electrophoresis (IFE) is the standard method for confirming the presence of a monoclonal protein (M-protein) at multiple myeloma (MM) diagnosis. IFE is also essential at assessment of complete response (CR) and stringent CR during treatment. As the CR assessment is influenced by daratumumab and isatuximab, HYDRASHIFT assays were developed.
METHODS: Samples from patients under treatment that included daratumumab or isatuximab were tested and monitored by IFE on the HYDRASYS system using HYDRASHIFT assays (HYDRASYS/HYDRASHIFT) and by IFE on the Epalyzer2 system (Epalyzer).
RESULTS: The IFE using HYDRASYS/HYDRASHIFT avoided a false positive caused by drug-related IgG-κ and contributed to accurate assessment of CR. Furthermore, HYDRASYS/HYDRASHIFT detected small M-proteins at early relapse and detected free light chains (FLCs) in patients with renal impairment exhibiting high serum FLCs despite being often missed on Epalyzer.
CONCLUSIONS: Sensitivity and specificity of M-protein detection vary greatly depending on the IFE system and reagents used.

UNASSIGNED: Detecting monoclonal protein (M-protein), a hallmark of plasma cell disorders, traditionally relies on methods such as protein electrophoresis, immune-electrophoresis, and immunofixation electrophoresis (IFE). Mass spectrometry (MS)-based methods, such as matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and electrospray ionization-quadrupole time-of-flight (ESI-qTOF) MS, have emerged as sensitive methods. We explored the M-protein-detection efficacies of different MS techniques.
UNASSIGNED: To isolate immunoglobulin and light chain proteins, six types of beads (IgG, IgA, IgM, kappa, lambda, and mixed kappa and lambda) were used to prepare samples along with CaptureSelect nanobody affinity beads (NBs). After purification, both MALDI-TOF MS and liquid chromatography coupled with Synapt G2 ESI-qTOF high-resolution MS analysis were performed. We purified 25 normal and 25 abnormal IFE samples using NBs and MALDI-TOF MS (NB-MALDI-TOF).
UNASSIGNED: Abnormal samples showed monoclonal peaks, whereas normal samples showed polyclonal peaks. The IgG and mixed kappa and lambda beads showed monoclonal peaks following the use of daratumumab (an IgG/kappa type of monoclonal antibody) with both MALDI-TOF and ESI-qTOF MS analysis. The limits of detection for MALDI-TOF MS and ESI-qTOF MS were established as 0.1 g/dL and 0.025 g/dL, respectively. NB-MALDI-TOF and IFE exhibited comparable sensitivity and specificity (92% and 92%, respectively).
UNASSIGNED: NBs for M-protein detection, particularly with mixed kappa-lambda beads, identified monoclonal peaks with both MALDI-TOF and ESI-qTOF analyses. Qualitative analysis using MALDI-TOF yielded results comparable with that of IFE. NB-MALDI-TOF might be used as an alternative method to replace conventional tests (such as IFE) to detect M-protein with high sensitivity.

Current guidelines recommend screening with serum M-protein and serum-free light chain analysis (S-FLC) when an M-protein-related disorder is suspected. Many patients with multiple myeloma will be overlooked if only serum M-protein is measured. Despite this, the general practitioners in some areas of Denmark cannot order S-FLC. This review aims to disseminate knowledge of the S-FLC analysis, its applicability, and limitations in the diagnostic workup for suspected monoclonal gammopathies.

BACKGROUND: Polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes (POEMS) syndrome is a rare plasma cell (PC) neoplasm with associated paraneoplastic syndrome. According to the current diagnostic criteria, peripheral polyneuropathy and monoclonal PC proliferative disorder represent two mandatory criteria.
METHODS: We report a 54-year-old male with peripheral neuropathy of bilateral lower limbs, sclerotic bone lesions, elevated vascular endothelial growth factor (VEGF) levels, splenomegaly, extravascular volume overload, endocrinopathy, and skin hemangiomas. Of note, serum and urine protein electrophoresis (PEP) and immunofixation electrophoresis (IFE) of this patient indicated undetectable M-protein and the normal ratio of free light chains κ and λ (FLC-R (κ/λ)). No monoclonal PCs were found in bone marrow examinations or biopsy of diseased bones. However, his clinical manifestations matched most of the diagnostic criteria. After excluding other diseases that are easily confused with POEMS syndrome, the diagnosis of variant POEMS syndrome with undetectable M-protein was proposed. The patient obtained clinically significant improvement and elevated VEGF returned to normal after 6 months of treatment with lenalidomide plus dexamethasone.
CONCLUSIONS: Monoclonal PC dyscrasia (M-protein) while being a mandatory criterion for POEMS syndrome is undetectable in a considerable amount of patients that otherwise demonstrate typical symptoms. Here, we reported a case of variant POEMS syndrome with featured clinical manifestations, elevated VEGF levels, and good response to therapies targeting PCs but no evidence of M-protein. Therefore, negative results in M-protein and monoclonal PCs aren\'t enough to reject the diagnosis of POEMS syndrome. It is imperative to recognize the variant form of POEMS syndrome.

As no unified treatment protocol or evidence yet exists for plasmapheresis without plasma, this study explored the outcomes of using 4% human albumin (ALB) solution as a replacement solution in patients undergoing plasma exchange for multiple myeloma (MM) patients with acute kidney injury (AKI). This study was prospectively registered (ChiCTR2000030640 and NCT05251896). Bortezomib-based chemotherapy plus therapeutic plasmapheresis (TPP) with 4% human ALB solution was assessed for three years in patients with MM aged >18 years, with AKI according to the Kidney Disease Improving Global Outcomes criteria, and without previous renal impairment from other causes. The primary endpoints were changes in renal function over 18 weeks and survival outcomes at 36 months. The secondary endpoints were the incidence of adverse reactions and symptom improvement. Among the 119 patients included in the analysis, 108 experienced renal reactions. The M protein (absolute changes: median -12.12%, interquartile ranges (IQRs) -18.62 to -5.626) and creatine (median -46.91 μmol/L, IQR -64.70 to -29.12) levels decreased, whereas the estimated glomerular filtration rate (eGFR) increased (median 20.66 mL/(min·1.73 m2), IQR 16.03-25.29). Regarding patient survival, 68.1% and 35.3% of patients survived for >12 and >36 months, respectively. The three symptoms with the greatest relief were urine foam, poor appetite, and blurred vision. All 11 patients (7.6%) who experienced mild adverse reactions achieved remission. In conclusion, in MM patients with AKI, plasma-free plasmapheresis with 4% human ALB solution and bortezomib-based chemotherapy effectively alleviated light chain damage to kidney function while improving patient quality of life.

UNASSIGNED: 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. We established feasibility of measuring MRD by MS in the PB in the posttransplant setting, despite unavailability of pretreatment calibration samples. There was high agreement between MRD by MS in the PB and paired bone marrow (BM) MRD results at the 10-5 threshold, assessed by either next-generation sequencing (NGS) or multiparameter flow cytometry (MFC) (70% and 67%, respectively). Agreement between PB MS and both BM MRD methods was lowest early after transplant and increased with time. MS negativity was associated with improved progression-free survival (PFS), which, in landmark analysis, reached statistical significance after 18 cycles after transplant. Combined PB/BM MRD negativity by MFC or NGS was associated with superior PFS compared with MRD negativity by only 1 modality. Sustained MS negativity carried similar prognostic performance to sustained BM MRD negativity at the 10-5 threshold. Overall, posttransplant MS assessment was feasible and provided additional prognostic information to BM MRD negativity. Further studies are needed to confirm the role and optimal timing of MS in disease evaluation algorithms. The ATLAS trial is registered at www.clinicaltrials.gov as #NCT02659293.

BACKGROUND: Isatuximab, an IgG-kappa (IgGκ) anti-cluster of differentiation 38 (CD38) monoclonal antibody approved for use in patients with relapsed or refractory multiple myeloma (MM), can potentially interfere with the visualization of endogenous monoclonal protein (M-protein) on standard immunofixation electrophoresis (IFE) and lead to inaccurate classification of a patient\'s response to therapy. The Hydrashift 2/4 isatuximab IFE assay (Hydrashift isatuximab assay) removes isatuximab interference from IFE. Using samples from patients enrolled in clinical trials of isatuximab-based therapy for MM, we demonstrate how the Hydrashift isatuximab assay improves the ability to detect residual M-protein and offer recommendations for when the assay is most useful.
METHODS: Samples from 141 patients with a variety of known M-protein isotypes were selected and analyzed by standard IFE and the Hydrashift isatuximab assay. A positive control containing isatuximab was run on every standard IFE and Hydrashift gel.
RESULTS: The Hydrashift isatuximab assay reliably shifted the migration of isatuximab in patient samples. Standard IFE was adequate for determining 104 patients\' M-protein status, and the Hydrashift isatuximab assay confirmed these results. In samples from 37 patients with a history of IgGκ MM and a single IgGκ band visible on standard IFE near the isatuximab migration site, the Hydrashift isatuximab assay was able to separate isatuximab from endogenous M-protein, identifying residual M-protein in 17 samples and preventing false-positive interpretations of standard IFE in 20 samples.
CONCLUSIONS: The Hydrashift isatuximab assay is most useful in patients with known IgGκ MM when a single IgGκ band appears near the isatuximab migration site on standard IFE during isatuximab-based therapy.
UNASSIGNED: NCT03275285 and NCT03319667.

OBJECTIVE: Multiple myeloma (MM) is a plasma cell malignancy characterized by a monoclonal expansion of plasma cells that secrete a characteristic M-protein. This M-protein is crucial for diagnosis and monitoring of MM in the blood of patients. Recent evidence has emerged suggesting that N-glycosylation of the M-protein variable (Fab) region contributes to M-protein pathogenicity, and that it is a risk factor for disease progression of plasma cell disorders. Current methodologies lack the specificity to provide a site-specific glycoprofile of the Fab regions of M-proteins. Here, we introduce a novel glycoproteogenomics method that allows detailed M-protein glycoprofiling by integrating patient specific Fab region sequences (genomics) with glycoprofiling by glycoproteomics.
METHODS: Glycoproteogenomics was used for the detailed analysis of de novo N-glycosylation sites of M-proteins. First, Genomic analysis of the M-protein variable region was used to identify de novo N-glycosylation sites. Subsequently glycopeptide analysis with LC-MS/MS was used for detailed analysis of the M-protein glycan sites.
RESULTS: Genomic analysis uncovered a more than two-fold increase in the Fab Light Chain N-glycosylation of M-proteins of patients with Multiple Myeloma compared to Fab Light Chain N-glycosylation of polyclonal antibodies from healthy individuals. Subsequent glycoproteogenomics analysis of 41 patients enrolled in the IFM 2009 clinical trial revealed that the majority of the Fab N-glycosylation sites were fully occupied with complex type glycans, distinguishable from Fc region glycans due to high levels of sialylation, fucosylation and bisecting structures.
CONCLUSIONS: Together, glycoproteogenomics is a powerful tool to study de novo Fab N-glycosylation in plasma cell dyscrasias.

BACKGROUND: To improve the early detection rate of multiple myeloma (MM), the M-protein screening system has been performed in the hospital population at Zhongshan Hospital Fudan University since 2014, with electrophoretic-based monoclonal immunoglobulin (M-protein) screening integrated into the blood biochemistry panel. This study updated 7-year follow-up findings of MM patients diagnosed by screening-driven and symptom-driven approaches.
METHODS: The retrospective study compared the characteristics and outcomes of patients diagnosed through two patterns by reviewing the plasma cell disease database from January 2014 to October 2021. The screening-driven group included patients diagnosed through the screening system during workups of unrelated medical conditions or routine checkups. In contrast, patients who visited or were referred to the hematological department due to myeloma-related end-organ damage were categorized into the symptom-driven group.
RESULTS: There were 3,110,218 serum protein electrophoresis (SPEP) tests performed during 7 years, with 1.95% (60,609) patients yielding positive SPEP results. Of 911 confirmed MM cases (excluding concurrent amyloidosis), 366 were assigned to the screening-driven group, while 545 were to the symptom-driven group. Compared to the symptom-driven group, the screening group had more IgG subtypes, earlier International Stage System stages, fewer disease-related symptoms, lower ECOG scores, less extramedullary disease, a lower percentage of bone marrow plasma cells, and a lower level of lactate dehydrogenase. Frontline response results of two groups were similar. Patients detected through screening had a significantly improved median progression-free survival (PFS) than the symptom-driven group (62.2 vs. 24.9 months, p < 0.001, HR: 2.12, 95% CIs: 1.69-2.65), with median follow-ups of 32.6 and 27.4 months. Furthermore, the median overall survival (OS) was significantly longer in patients of the screening group (not reached vs. 62.3 months, p < 0.001, HR: 2.49, 95% CIs: 1.81-3.41). After being adjusted for well-acknowledged myeloma prognostic factors, the screening-driven diagnostic pattern remained an independent prognostic factor indicating improved PFS and OS in MM patients.
CONCLUSIONS: Routine M-protein screening for MM in the hospital population results in an earlier diagnosis and better patient outcomes.

UNASSIGNED: Plasma cell myeloma (PCM) is a monoclonal gammopathy (MGM) characterized by proliferation of abnormal clone of plasma cells infiltrating the bone marrow with consequent end organ damage. The clonal plasma cells secrete a single clone of immunoglobulins (Ig) leading to presence of M-protein in the serum and/or urine. The M-protein is appreciated as a discrete band on serum protein electrophoresis (SPE) in the gamma globulin region, also called the M-band. Biclonal gammopathy (BGM) occurs due to neoplastic transformation of a plasma cell clone undergoing Ig class switching or due to an independent neoplastic transformation event yielding proliferation of unrelated plasma cell clones, therefore resulting in two distinct M-bands on SPE. It is, however, vital to distinguish a true BGM from an apparent one (MGM presenting with two distinct bands on SPE) so as to make an accurate diagnosis. Hereby, we report a case of a 61-year-old man, diagnosed with PCM and presenting with two discrete bands on SPE (simulating a BGM) which turned out to be monoclonal in nature.