意义未明的单克隆免疫球蛋白血症的病程演变、鉴别诊断及其干预策略:第54届美国血液学会年会报道

 【摘要】　意义未明的单克隆免疫球蛋白血症（monoclonal gammopathy of undetermined significances,MGUS）被界定为癌前克隆性疾病。其在50岁以上人群中的发病率达到4.2 %,且以每年1 %的高风险向多发性骨髓瘤（multiple myeloma,MM）和相关的恶性疾病转化。确定其病程演变将指导临床诊断和治疗。大多数MGUS患者仅需随访观察。而少部分患者则经过冒烟型骨髓瘤（smoldering multiple myeloma,SMM）阶段进展为MM,或者因M蛋白导致终末器官损害,发展为轻链型疾病,如轻链型淀粉样变性、轻链沉淀病等,需要启动药物干预措施。2012年第54届美国血液学会（ASH）年会进行了这部分内容的详细报道。     

Risk and Severity of COVID-19 Infection in Monoclonal Gammopathy of Undetermined Significance: A 3-Year Propensity Matched Cohort Study

IntroductionMonoclonal gammopathy of undetermined significance (MGUS) is a premalignant disorder causing monoclonal plasma cell proliferation in bone marrow. This population is at risk of developing multiple myeloma (MM) and severe viral infections; risk factors of severe COVID-19 infection. Using TriNetX, a global platform providing data of 120 million patients, we aimed to quantify the risk and severity of COVID-19 in MGUS patients.Patients and MethodsA retrospective cohort analysis was performed using the TriNetX Global Collaborative Network. From January 20, 2020, to January 20, 2023, we identified a cohort of 58,859 MGUS patients and compared to non-MGUS patients, determined by relevant diagnosis/LOINC test codes. After 1:1 propensity score-matching, we identified COVID-19 cases to quantify risk and identify patients who had been hospitalized, ventilated/intubated, and deceased to quantify severity. Measures of association and Kaplan-Meier analysis were conducted.ResultsAfter propensity-score matching, there were 58,668 patients in both cohorts. MGUS patients were found to be at a reduced risk of contracting COVID-19 (RR 0.88, 95% CI 0.85-0.91). MGUS patients with COVID-19 showed higher mortality risk and decreased survival time compared to the general population (HR 1.14, 95% CI 1.01-1.27). MGUS patients with COVID-19 who were hospitalized exhibited significantly decreased survival time (log-rank test, P = 0.04).ConclusionAs COVID-19 remains a looming health concern, especially amongst vulnerable populations, our analysis emphasizes the need for adequate vaccination and treatment regimens as well as an understanding of the severity of infection in MGUS patients and justification for precautionary measures.     

Overweight/Obesity and Monoclonal Gammopathy of Undetermined Significance

BackgroundObesity and high body mass index (BMI) are associated with increased incidence of multiple myeloma (MM). MM usually evolves from a precursor asymptomatic disease, namely monoclonal gammopathy of undetermined significance (MGUS). MGUS progresses to MM at a 1% annual rate; however, risk factors predisposing to MGUS are not completely understood. We conducted a systematic review to assess the relationship between obesity and high BMI with MGUS prevalence and progression to MM. To our knowledge, this is the first systematic review evaluating the role of obesity in MGUS.Patients and MethodsWe searched the Medline database and ClinicalTrials.gov for studies investigating BMI and obesity association with MGUS incidence and progression. The algorithm consisted of a predefined combination of the words “obesity,” “obese,” “body mass index,” “overweight,” “diet,” “nutrition,” “food,” “dietary,” “adiponectin,” “monoclonal gammopathy,” and “MGUS”.ResultsOverall, 12 articles were retrieved, including 11 eligible articles and 1 clinical trial. More than 57,068 patients were evaluated in this systematic review. Discrepancies between the identified studies were noted. Multiple studies support the notion that obesity or high BMI are positively linked to MGUS prevalence and transition to MM. In contrast, other studies revealed no such association. Visceral adipose tissue metabolic activity and decreased adiponectin concentrations were identified as biomarkers of MGUS progression to MM.ConclusionObesity and increased BMI seem to be implicated both in MGUS development and progression to MM. Further studies should be designed to confirm this hypothesis.     

Prognostic Biomarkers in the Progression From MGUS to Multiple Myeloma: A Systematic Review

Multiple myeloma (MM), characterized by malignant plasma cells in the bone marrow, is consistently preceded by asymptomatic premalignant stage monoclonal gammopathy of undetermined significance (MGUS). These MGUS patients have an annual risk of 1% to progress to MM. Clinical, imaging, and genomic (genetic and epigenetic) factors were identified, whose presence increased the risk of progression from MGUS to MM. In this systematic review we summarize the currently identified clinical, imaging, and genomic biomarkers suggested to increase the progression risk or shown to be differentially expressed/present between both cohorts of patients. Despite the wide range of proposed markers, there are still no reliable biomarkers to individually predict which MGUS patient will progress to MM and which will not. Research on biomarkers in the progression from MGUS to MM will give more insight in the unknown pathogenesis of this hematological malignancy. This would improve research by elucidating new pathways and potential therapeutic targets as well as clinical management by closer follow-up and earlier treatment of high-risk MGUS patients.     

Monoclonal gammopathy of undetermined significance

Monoclonal gammopathy of undetermined significance (MGUS) is characterized by the presence of a monoclonal protein (M-protein) without evidence of multiple myeloma (MM), Waldenstrom's macroglobulinemia (WM), amyloidosis (AL), or a related plasma cell proliferative disorder. Agarose gel electrophoresis followed by immunofixation is recommended for recognition of an M-protein. Monoclonal gammopathy of undetermined significance is found in approximately 3% of persons > 70 years of age and in about 1% of those > 50 years old. In a series of 1384 patients from Southeastern Minnesota in whom MGUS was diagnosed at Mayo Clinic from 1960 through 1994, the risk of progression was 1% per year. This risk of progression continued even after > or = 25 years of a stable M-protein. The risk for developing MM, WM, or AL was increased 25-fold, 46-fold, and 8.4-fold, respectively. The concentration of the serum M-protein, abnormal serum free light-chain ratio, and the presence an immunoglobulin (Ig)M or an IgA M-protein were risk factors for progression. The presence of a urine M-protein or the reduction of > or = 1 uninvolved immunoglobulins was not a risk factor for disease progression. Patients must be monitored for progressive disease throughout their lives. Variants of MGUS consist of IgM MGUS, biclonal gammopathies, triclonal gammopathies, idiopathic Bence Jones (light-chain) proteinuria, and IgD MGUS. Monoclonal gammopathy of undetermined significance may be associated with many disorders, including lymphoproliferative diseases, leukemia, von Willebrand's disease, connective tissue diseases, and neurologic disorders. Epidemiologic and statistical methods must be used to evaluate these associations.     

High Dimensional Immune Profiling of Smoldering Multiple Myeloma Distinguishes Distinct Tumor Microenvironments

BackgroundMultiple myeloma (MM) is a malignancy of plasma cells that arises from premalignant Monoclonal Gammopathy of Undetermined Significance (MGUS) and often progresses through an asymptomatic Smoldering (SMM) phase. Understanding the interactions between abnormal clonal plasma cells and the tumor microenvironment (TME) in the early disease states (MGUS, SMM) may inform risk assessment and therapy.Patients and MethodsWe performed high dimensional immunologic analysis of bone marrow specimens from 73 subjects with SMM by mass cytometry and T cell receptor sequencing of CD138-depleted bone marrow (BM) mononuclear cells, and proteomics and seromic profiling of BM plasma. Analysis of individual assay data identified self-organizing subgroups of SMM patients. We then applied novel bioinformatic methods to integrate data from pairs, trios, and quartets of assays.ResultsMass cytometry, TCRSeq and proteomics identified three taxa (sing. taxon) of subjects that shared common characteristics across all three assays. Differential levels of BM plasma pleiotropin (PTN) and BM T cells and their productive clonality emerged as strong distinguishing factors among these taxa.ConclusionThese results suggest that the continuum from MGUS to MM does not consist of a single pathway in the TME, and that complex interactions between myeloma cells and the TME may ultimately determine progression and inform clinical management.     

A retrospective study to evaluate the work-up and follow-up of patients with monoclonal gammopathy of undetermined significance

BackgroundMonoclonal gammopathy of undetermined significance (MGUS) is a plasma cell proliferative disorder that transforms into multiple myeloma and other serious B-cell disorders at an approximate rate of 1% per year; these patients are also at increased risk for fractures.Patients and MethodsWe conducted a retrospective, multicenter study of 100 patients from seven community health clinics to gain a better understanding of the work-up, follow-up, and treatment of these patients.ResultsMGUS patients appear to undergo inadequate work-up, follow-up, and treatment in the community setting.ConclusionsPhysicians should adhere to recently established guidelines to ensure that MGUS patients receive optimal care for this condition.     

Monoclonal Gammopathies After Renal Transplantation: A Single-center Study

IntroductionPlasma cell disorders (PCDs) are clonal plasma cell disorders that include conditions such as monoclonal gammopathy of undetermined significance (MGUS), monoclonal gammopathy of renal significance (MGRS), multiple myeloma (MM), smoldering MM (SMM), solitary plasmacytoma, and light-chain (AL) amyloidosis. The risk factors associated with and the clinical course of PCDs after renal transplantation is not well established although immunosuppressive protocols may impact the incidence and natural history of PCDs posttransplant.Patients and MethodsThis single-center retrospective study evaluated patients with a history of renal transplant who developed a PCD between January 1, 2014-December 31, 2018.ResultA total of 41 patients met the inclusion criteria including 29 with MGUS and 12 with symptomatic PCD (4 with MM, 2 with SMM, 4 with MGRS, 1 with AL amyloidosis, and 1 with solitary plasmacytoma). The median follow-up of survivors was 41.6 months. Three patients (1 with MGUS and 2 with MGRS) progressed to MM during the follow-up period. There was a male preponderance in both groups. There was no correlation between the donor and immunosuppressive regimen and the development of a PCD. Patients with symptomatic PCD had higher serum creatinine and M-protein levels at diagnosis and higher free light chain ratio and plasma cell burden. There was also a higher percentage of allograft failure noted in the symptomatic PCD subset 50% (n = 6), whereas only 23% (n = 7) of patients had allograft failure in the MGUS group.ConclusionThis study shows the importance of considering monoclonal gammopathy in the differential of renal dysfunction after kidney transplant and the need to follow these patients closely to monitor for progression to symptomatic PCD.     

Monoclonal Gammopathy of Undetermined Significance and Smoldering Multiple Myeloma

Monoclonal gammopathy of undetermined significance (MGUS) is characterized by the presence of a serum monoclonal (M) protein level less than 3 g/dL, less than 10% clonal plasma cells in the bone marrow, and the absence of hypercalcemia, renal insufficiency, anemia, or bone lesions attributable to a clonal plasma cell disorder. Patients may be tested for a monoclonal gammopathy by serum protein electrophoresis, immunofixation, and the free light chain (FLC) assay. The prevalence of MGUS is 3% for persons more than 50 years of age and 5% in those more than 70 years of age. The risk of progression to multiple myeloma or a related disorder is 1% per year. The size and type of M protein, the number of bone marrow plasma cells, and the results of the FLC ratio are independent risk factors for progression. Smoldering multiple myeloma (SMM) is a more advanced premalignant phase than MGUS and is characterized by more than 3 g/dL of serum M protein, more than 10% clonal plasma cells in the bone marrow, or both, with no evidence of end-organ damage.     

Blood-based risk stratification for pre-malignant and symptomatic plasma cell neoplasms to improve patient management

Standard risk stratification (sRisk) guides clinical management in monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM) and multiple myeloma (MM). Nonetheless, clinical results are considerably heterogeneous among patients with similar risk status. Blood and bone marrow samples from 276 MGUS, 56 SMM and 242 MM in regular clinical practice were analyzed at diagnosis by flow cytometry. Higher levels of aberrant circulating plasma cells (cPC) (> 0.0035% of leukocytes), combined with albumin, beta2-microglobuline and lactate-dehydrogenase levels, offered minimally-invasive risk stratification (RcPC) with results comparable to sRisk. RcPC and sRisk 10-year progression-free-survival (10y-PFS) rates were: 93.8% vs. 95.1% for low-risk, 78.4% vs. 81.7% for intermediate-risk and 50.0% vs. 47.8% for high-risk MGUS; 58.3% vs. 57.8% low-risk, 44.4% vs. 45.8% intermediate-risk and 8.9% vs. 15.0% high-risk SMM; and 44.4% vs. 44.4% low-risk, 36.1% vs. 36.8% intermediate-risk, and 13.3% vs. 16.2% high-risk MM. Circulating-PC > 0.0035% vs. cPC<0.0035% was an independent prognostic factor for PFS (HR=4.389, P=1.2×10^-15, Harrell C-statistic =0.7705±0.0190) and over-all survival (OS, HR=4.286, 2.3×10^-9, Harrell C-statistic =0.8225±0.0197) that complemented sRisk in patients with low-sRisk (10y-PFS rates 48.1% vs. 87.3%, P=1.2×10^-8) and intermediate-sRisk (10y-PFS rates 28.9% vs. 74.1%, P=8.6×10^-12). Patients with high cPCs values are associated with higher proliferation and lower apoptosis rates of PC. Circulating-PC > 0.0035% identified MGUS, SMM and MM patients at higher risk of progression or death and predicted a cohort of patients that after relapse from stringent complete response showed shorter OS. These patients could benefit from early consolidation therapy, tandem ASCT or intensive maintenance.     

Disparities in the prevalence, pathogenesis and progression of monoclonal gammopathy of undetermined significance and multiple myeloma between blacks and whites

There is marked racial disparity in the incidence of monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma, with a two to threefold increased risk in blacks compared with whites. The increased risk has been seen both in Africans and African Americans. Similarly, an increased risk of monoclonal gammopathies in blacks compared with whites has been noted after adjusting for socioeconomic and other risk factors, suggesting a genetic predisposition. The higher risk of multiple myeloma in blacks is likely a result of the higher prevalence of the premalignant MGUS stage; there are no data to suggest that blacks have a higher progression rate of MGUS to myeloma. Studies are emerging that suggest the baseline cytogenetic characteristics, and progression may differ by race. In contrast, to the increased risk noted in blacks, studies suggest that the risk may be lower in certain racial and ethnic groups, notably persons from Japan and Mexico. We review the literature on racial disparity in the prevalence, pathogenesis and progression of MGUS and multiple myeloma between blacks and whites. We also discuss future directions for research that could inform management of these conditions and positively influence patient outcomes.     

Understanding biology to tackle the disease: Multiple myeloma from bench to bedside,and back

Answer questions and earn CME/CNE Multiple myeloma (MM) is a cancer of antibody‐producing plasma cells. The pathognomonic laboratory finding is a monoclonal immunoglobulin or free light chain in the serum and/or urine in association with bone marrow infiltration by malignant plasma cells. MM develops from a premalignant condition, monoclonal gammopathy of undetermined significance (MGUS), often via an intermediate stage termed smoldering multiple myeloma (SMM), which differs from active myeloma by the absence of disease‐related end‐organ damage. Unlike MGUS and SMM, active MM requires therapy. Over the past 6 decades, major advancements in the care of MM patients have occurred, in particular, the introduction of novel agents (ie, proteasome inhibitors, immunomodulatory agents) and the implementation of hematopoietic stem cell transplantation in suitable candidates. The effectiveness and good tolerability of novel agents allowed for their combined use in induction, consolidation, and maintenance therapy, resulting in deeper and more sustained clinical response and extended progression‐free and overall survival. Previously a rapidly lethal cancer with few therapeutic options, MM is the hematologic cancer with the most novel US Food and Drug Administration‐approved drugs in the past 15 years. These advances have resulted in more frequent long‐term remissions, transforming MM into a chronic illness for many patients. CA Cancer J Clin 2014;64:422–444. © 2014 American Cancer Society.     

Serum Levels of Total-RANKL in Multiple Myeloma

BackgroundReceptor activator of nuclear factor-κB ligand (RANKL) plays a key role in osteoclast activation in myeloma bone disease. The increased expression of RANKL in the bone marrow microenvironment was demonstrated in several studies, but there are only rare data on circulating RANKL levels in patients with multiple myeloma (MM).Patients and MethodsIn the current study, we investigated the clinical significance of serum RANKL levels, using an enzyme-linked immunosorbent assay test that detects both free and osteoprotegerin (OPG)-bound RANKL (total-RANKL, tRANKL) in patients with newly diagnosed MM (n = 93) and monoclonal gammopathy of undetermined significance (MGUS; n = 20) compared with healthy controls (n = 20).ResultsCirculating serum tRANKL was significantly elevated in patients with MM compared with controls (P < .001) or MGUS (P < .001). Furthermore, tRANKL levels were higher in smoldering MM versus MGUS (P = .031) and in symptomatic versus smoldering MM (P < .001). Serum tRANKL increased parallel to International Staging System stages I to III (P = .004) and correlated with the presence of lytic bone lesions (P < .001). Total-RANKL was a prognostic factor for overall survival in symptomatic MM (P = .043). A significantly longer progression-free survival was observed in patients with a > 50% decrease in tRANKL levels after 3 months of combined chemotherapy and bisphosphonate treatment.ConclusionOur study demonstrates for the first time that serum tRANKL reflects advanced disease, lytic bone destruction, and poor prognosis in MM.     

Monoclonal gammopathy of undetermined significance (MGUS) and smoldering myeloma (SMM): a practical guide to management

Monoclonal gammopathy of undetermined significance and smoldering multiple myeloma are precursor conditions of symptomatic multiple myeloma (MM). Diagnostic principles are aimed at excluding MM requiring therapy, other conditions associated with paraproteins that may require different management, and risk stratifying patients for the purposes of tailored follow‐up and investigation. The International Myeloma Working Group have recently published a revised definition of MM, which singles out a small group of patients with smoldering multiple myeloma who are at very high risk of progression and organ damage; such patients are now included under the definition of MM and recommended to start anti‐myeloma treatment. Furthermore, the recently published National Institute of Health and Care Excellence guideline recommends cross‐sectional imaging techniques in place of skeletal survey. These recent recommendations are discussed, and practical guidance for investigation and management are presented.     

Serum BCMA levels predict outcomes in MGUS and smoldering myeloma patients

Soluble BCMA (sBCMA) levels are elevated in monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM). However, the association between sBCMA levels and prognosis in MGUS and SMM has not been studied. We retrospectively analyzed sBCMA levels in stored samples from 99 MGUS and 184 SMM patients. Baseline sBCMA levels were significantly higher in MGUS and SMM patients progressing to MM during clinical follow up. When stratified according to the median baseline sBCMA level for each cohort, higher levels were associated with a shorter PFS for MGUS (HR 3.44 comparing sBCMA ≥77 vs <77 ng/mL [95% CI 2.07–5.73, p < 0.001] and SMM (HR 2.0 comparing sBCMA ≥128 vs <128 ng/mL, 95% 1.45–2.76, p < 0.001) patients. The effect of sBCMA on PFS was similar even after adjusting for the baseline MGUS or SMM risk stratification. We evaluated paired serum samples and found that sBCMA increased significantly in MGUS and SMM patients who eventually progressed to MM, whereas among MGUS non-progressors the sBCMA level remained stable. While our results require independent validation, they suggest that sBCMA may be a useful biomarker to identify MGUS and SMM patients at increased risk of progression to MM independent of the established risk models.Subject terms: Myeloma, Tumour immunology, Prognosis     

Patient Characteristics,Treatment Patterns,and Outcomes in Triple-Class Exposed Relapsed/Refractory Multiple Myeloma Patients,a Retrospective Observational Study Using Czech Registry Data

BackgroundAlthough novel therapies improved prognosis of multiple myeloma (MM) patients, clinical outcomes in the multi-refractory population are still poor.Patients and MethodsWe reviewed data from the Czech Registry of Monoclonal Gammopathies, identified and characterized triple-class exposed (3CE) relapsed/refractory MM patients, treatment patterns after 3CE, assessed overall survival (OS), progression-free survival (PFS), time to next treatment (TTNT), explored cohorts with and without triple- and penta-refractoriness.ResultsIn 83 3CE patients who started subsequent therapies, the median OS was 14.2 months (95% CI, 8.5-19.9), PFS 6.2 months (95% CI, 3.9-8.5), and TTNT 7.2 months (95% CI, 4.6-9.8). Triple- and penta-class refractory patients had a significantly worse prognosis in all outcomes. Their life expectancy was shorter, the disease progression started earlier, and the TTNT was shorter, which increased likelihood of becoming refractory to more therapies. Time-to-event results from the first index date and all index dates analyses were very similar.ConclusionSimilar to previous studies from the US and Europe, our results show a high disease burden. Introduction of novel therapies, such as CAR-T cells, new bispecific and trispecific monoclonal antibodies, and other drugs, is expected to bring significant benefits to these patients.     

Coexistence of Myeloproliferative Neoplasm and Plasma-Cell Dyscrasia

IntroductionPhiladelphia chromosome-negative myeloproliferative neoplasms (MPNs) include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), and are characterized by clonal proliferation of hematopoietic cells in the bone marrow. There are numerous case reports and reviews reporting patients with coexisting MPN and plasma-cell disease such as multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS).MethodsWe report 15 patients treated at our institution over a 5-year period (January 2008 to December 2012) with a diagnosis of both an MPN and MGUS or MM. We also reviewed and summarized published case reports and studies describing the coexistence of these two disease entities.ResultsMost patients (12/15) had an MPN diagnosis made before or at the same time as the MGUS/MM diagnosis. Eventually, 2 patients developed a lymphoid leukemia, 1 patient developed lymphoma, and 1 patient developed acute myeloid leukemia, raising the question of whether patients with coexistence of myeloid- and lymphoid-derived neoplasms are more prone to leukemic or lymphomatous transformation. We did not find any treatment-related effect that could have contributed to the development of coexisting MGUS or MM and MPN. Of the 7 patients with an abnormal karyotype, 3 patients had trisomy 8.ConclusionAt present, management strategies are aimed at treating the MPN and regularly monitoring the MGUS for transformation to an overt plasma-cell malignancy. However, for patients who develop overt MM, management is focused more on treating the myeloma and monitoring the MPN. It has not yet been definitively shown that these 2 entities arise from a common-ancestor hematopoietic stem cell.     

Monoclonal Gammopathy of Undetermined Significance: Why Identification of These Patients and Assessment of Their Skeletons Is Important

Monoclonal gammopathy of undetermined significance (MGUS) is a plasma cell disorder characterized by the presence of a serum monoclonal immunoglobulin (M-protein) at ≤ 3 g/dL. It is an asymptomatic premalignant disorder that can progress to multiple myeloma and related B-cell disorders. Recent studies have suggested the association of MGUS with enhanced bone loss and debilitating skeletal complications, particularly vertebral compression fractures (VCFs) often leading to back pain. Early identification of MGUS and evaluation of bone status will facilitate prophylactic treatment with bisphosphonates to increase bone density and likely reduce the risk of fractures as well as identify patients with VCFs who might benefit from early surgical intervention. With proper diagnostic and treatment strategies, these patients will experience improved outcomes and quality of life.     

Bone marrow angiogenesis and mast cell density increase simultaneously with progression of human multiple myeloma

Immunohistochemical, cytochemical and ultrastructural data showing vivid angiogenesis and numerous mast cells (MCs) in the bone marrow of 24 patients with active multiple myeloma (MM) compared with 34 patients with non-active MM and 22 patients with monoclonal gammopathy of undetermined significance (MGUS) led us to hypothesize that angiogenesis parallels progression of MM, and that MCs participate in its induction via angiogenic factors in their secretory granules.     

Monoclonal gammopathy of undetermined significance and COVID-19: a population-based cohort study

Multiple myeloma (MM) patients have increased risk of severe coronavirus disease 2019 (COVID-19) when infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Monoclonal gammopathy of undetermined significance (MGUS), the precursor of MM has been associated with immune dysfunction which may lead to severe COVID-19. No systematic data have been published on COVID-19 in individuals with MGUS. We conducted a large population-based cohort study evaluating the risk of SARS-CoV-2 infection and severe COVID-19 among individuals with MGUS. We included 75,422 Icelanders born before 1976, who had been screened for MGUS in the Iceland Screens Treats or Prevents Multiple Myeloma study (iStopMM). Data on SARS-CoV-2 testing and COVID-19 severity were acquired from the Icelandic COVID-19 Study Group. Using a test-negative study design, we included 32,047 iStopMM participants who had been tested for SARS-CoV-2, of whom 1754 had MGUS. Among these participants, 1100 participants, tested positive, 65 of whom had MGUS. Severe COVID-19 developed in 230 participants, including 16 with MGUS. MGUS was not associated with SARS-CoV-2 infection (Odds ratio (OR): 1.05; 95% confidence interval (CI): 0.81–1.36; p = 0.72) or severe COVID-19 (OR: 0.99; 95%CI: 0.52–1.91; p = 0.99). These findings indicate that MGUS does not affect the susceptibility to SARS-CoV-2 or the severity of COVID-19.Subject terms: Epidemiology, Risk factors, Myeloma, Infectious diseases