Advances in the diagnosis, classification, risk stratification, and management of monoclonal gammopathy of undetermined significance: implications for recategorizing disease entities in the presence of evolving scientific evidence

Proteomic Alteration in the Progression of Multiple Myeloma: A Comprehensive Review

Multiple myeloma (MM) is an incurable hematologic malignancy. Most MM patients are diagnosed at a late stage because the early symptoms of the disease can be uncertain and nonspecific, often resembling other, more common conditions. Additionally, MM patients are commonly associated with rapid relapse and an inevitable refractory phase. MM is characterized by the abnormal proliferation of monoclonal plasma cells in the bone marrow. During the progression of MM, massive genomic alterations occur that target multiple signaling pathways and are accompanied by a multistep process involving differentiation, proliferation, and invasion. Moreover, the transformation of healthy plasma cell biology into genetically heterogeneous MM clones is driven by a variety of post-translational protein modifications (PTMs), which has complicated the discovery of effective treatments. PTMs have been identified as the most promising candidates for biomarker detection, and further research has been recommended to develop promising surrogate markers. Proteomics research has begun in MM, and a comprehensive literature review is available. However, proteomics applications in MM have yet to make significant progress. Exploration of proteomic alterations in MM is worthwhile to improve understanding of the pathophysiology of MM and to search for new treatment targets. Proteomics studies using mass spectrometry (MS) in conjunction with robust bioinformatics tools are an excellent way to learn more about protein changes and modifications during disease progression MM. This article addresses in depth the proteomic changes associated with MM disease transformation.

Monoclonal Gammopathy of Undetermined Significance in Patients With Transthyretin Amyloidosis (ATTR): Analysis Using the iStopMM Criteria

INTRODUCTION

To identify the prevalence of monoclonal gammopathy of undetermined significance (MGUS) in patients with transthyretin amyloid (ATTR). We used the iStopMM study revised reference ranges for serum free light-chain (sFLC) corrected for eGFR to identify ATTR patients with light-chain MGUS (LC-MGUS). Characteristics and frequencies of the ATTR cohort with underlying MGUS was compared to a cohort of MGUS patients without ATTR.

PATIENTS AND METHODS

A retrospective analysis of ATTR and MGUS patients evaluated at our center between January 2014 to December 2021. A total of 149, predominantly male (87.5%) ATTR patients with a median age of 82 were included. This cohort was compared to 228 MGUS patients.

RESULTS

Of the 149 ATTR patients, 27 (18.1%) had coexisting MGUS. Among ATTR patients with MGUS, 12/27 (44%) had LC-MGUS based on sFLC abnormalities assessed using the iStopMM reference ranges. Of the MGUS only cohort, 44/228 (19.3%) met criteria for LC-MGUS. Utilizing the iStopMM reference ranges, 6 ATTR patients did not meet criteria for abnormal sFLCs, uncovering a 20% false-positive rate.

CONCLUSION

We noted higher rates of MGUS, particularly LC-MGUS, among ATTR patients when compared to our MGUS only cohort. The high prevalence remained after utilizing the iStopMM sFLC corrected for eGFR reference ranges. Additionally, 6 ATTR patients with renal-dysfunction would have met MGUS criteria if not evaluated using the iStopMM revised measures. These findings emphasize careful interpretation of sFLC abnormalities and encourage providers to keep ATTR on the differential when work-up uncovers sFLC aberrations.

Assessing the frequency of CD163+ tumor-associated macrophages and CD3+ T lymphocytes between MGUS and plasma cell myeloma

Plasma cell dyscrasias (PCDs) are a heterogeneous group of diseases, and the most common is monoclonal gammopathy of undetermined significance (MGUS). This premalignant PCD consistently precedes multiple myeloma (MM), with a 1% risk of progression per year. Evading and suppressing the host immune system is an important step in the progression of MGUS to MM. This pilot study was designed to assess whether MGUS and MM have a distinct microenvironment, characterized by a unique distribution of immune cells, including tumor-associated macrophages. Evaluation of bone marrow (BM) tumor microenvironment was performed using immunohistochemical quantification of T cells (CD3), macrophages (CD68), and a macrophage subtype (CD163). The findings were compared between MGUS and MM to determine whether differences existed. The results suggest that there is a significantly lower percentage of CD3-positive, CD68-positive and CD163-positive immune effector cells in BM trephine biopsy samples from patients with MGUS than in those from patients with untreated MM (p < 0.001). Interestingly, in a patient treated for MM, the percentages of CD3+ and CD68+ cells were the same as those in other patients with untreated MM; however, the percentage of CD163+ cells reduced and correlated with low plasma cell count. Future studies are required to investigate whether the percentage of CD163+ cells is correlated with disease burden in patients with MM. If this is the case, then the level of soluble CD163 in plasma could be a potential biomarker of disease burden in patients with nonsecretory myelomas, in whom measurements of levels of paraprotein and free light chains are inconclusive.

Modulating glycosphingolipid metabolism and autophagy improves outcomes in pre-clinical models of myeloma bone disease

Patients with multiple myeloma, an incurable malignancy of plasma cells, frequently develop osteolytic bone lesions that severely impact quality of life and clinical outcomes. Eliglustat, a U.S. Food and Drug Administration-approved glucosylceramide synthase inhibitor, reduced osteoclast-driven bone loss in preclinical in vivo models of myeloma. In combination with zoledronic acid, a bisphosphonate that treats myeloma bone disease, eliglustat provided further protection from bone loss. Autophagic degradation of TRAF3, a key step for osteoclast differentiation, was inhibited by eliglustat as evidenced by TRAF3 lysosomal and cytoplasmic accumulation. Eliglustat blocked autophagy by altering glycosphingolipid composition whilst restoration of missing glycosphingolipids rescued autophagy markers and TRAF3 degradation thus restoring osteoclastogenesis in bone marrow cells from myeloma patients. This work delineates both the mechanism by which glucosylceramide synthase inhibition prevents autophagic degradation of TRAF3 to reduce osteoclastogenesis as well as highlighting the clinical translational potential of eliglustat for the treatment of myeloma bone disease.

Monoclonal gammopathy of undetermined significance: evaluation, risk assessment, management, and beyond

Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant state for a spectrum of lymphoplasmacytic malignancies. The risk of progression of MGUS to a symptomatic therapy requiring plasma cell dyscrasia is about 1% per year. Studies carried out over the previous 10 years have improved risk stratification of MGUS based on serologic and genomic evaluations, which has led to better management of patients. In this review, we address the epidemiology, diagnosis, and pathogenesis of MGUS and discuss risk-adapted best practice approaches to monitor patients.

An Analysis of M-protein in Plasma cell Dyscrasia Patients Identifies that IgG Lambda Subtype is More Commonly Associated with Normal Serum Free Light Chain (SFLC) Ratio

The determination of monoclonal protein (M-protein) by SPE, IFE and SFLC assay is fundamental in the diagnosis of Plasma cell proliferative disorder (PCPD). In the present study, we seek to assess the diagnostic performance and concordance of these three techniques in un-treated PCPD patients. All new patients with dysproteinemia and/or suspected PCPD were included in this retrospective observational study. The baseline parameters were retrieved from electronic medical records. SPE was performed on gel electrophoresis system; monoclonal component was identified by IFE. SFLC assays were performed by nephelometry using a latex-enhanced immunoassay. Total 402 patients of PCPD were included (10.9% of MGUS/SMM and 89.1% of multiple myeloma). The combination of SPE + rSFLC (ratio of kappa/lambda light chain) and SPE + IFE + rSFLC was able to detect M-protein across all subgroups of patients. In 61 patients, rSFLC values were within normal range (54.5% of MGUS/SMM and 10.3% of MM) and was more commonly seen with IgG lambda M-protein (57.4% vs. all-others). The median dFLC value, among these patients, was higher for MM than MGUS/SMM patients (23.8 vs. 14.4 mg/L, respectively). The combination of SPE and rSFLC can be reliably used to detect M-protein in PCPD patients. In a small subgroup of MM patients, despite the presence of an intact immunoglobulin (M-protein), the rSFLC is not abnormal. Historically, these patients should respond better to treatment. However, a further follow-up analysis with more number of such patients would be advantageous for better understanding.

Detection of Plasma Cell Disorders by Mass Spectrometry: A Comprehensive Review of 19,523 Cases

OBJECTIVES

To verify the analytical performance of a new mass spectrometry-based method, termed MASS-FIX, when screening for plasma cell disorders in a routine clinical laboratory.

PATIENTS AND METHODS

Results from 19,523 unique patients tested for an M-protein between July 24, 2018, and March 6, 2020, by a combination serum protein electrophoresis (SPEP) and MASS-FIX were examined for consistency with pretest implementation performance. MASS-FIX's ability to verify abnormal results from SPEP and free light chain measurements was then compared with that of immunofixation electrophoresis (IFE) using a separate cohort of 52,586 patients tested by SPEP/IFE during the same period.

RESULTS

Overall, 62.4% of our cohort was negative for an M-protein. Importantly, 7.3% of all specimens had an M spike on SPEP (0.1 to 8.5 g/dL) and MASS-FIX detected an M-protein in all these samples. Of all samples, 30.3% had M-proteins that were detected by MASS-FIX but the SPEP finding was too small for quantification. Of the positive samples, 5.7% contained a therapeutic monoclonal antibody. Of the positive samples, 4.1% had an N-glycosylated light chain (biomarker of high-risk plasma cell disorders). MASS-FIX confirmed a higher percentage of SPEP abnormalities than IFE. MASS-FIX was slightly more sensitive than IFE when confirming an M-protein in samples with an abnormal free light chain ratio. MASS-FIX had a very low sample repeat rate (1.5%). MASS-FIX was highly automatable resulting in a higher number of samples/technologist/day than IFE (∼30% more).

CONCLUSION

Overall, MASS-FIX was successful in maintaining validation characteristics. MASS-FIX was more sensitive in confirming SPEP abnormalities when compared with IFE. Ability to detect therapeutic monoclonal antibodies and glycosylated light chains was distinctly advantageous.

A case of monoclonal gammopathy of undetermined significance and minimal change disease complicated by bilateral pulmonary emboli

Nephrotic syndrome and monoclonal gammopathy of undetermined significance are thought to be associated with venous thromboembolism. However, the association is thought to be weak and is often ignored by clinicians. We present a rare case of sudden-onset bilateral pulmonary emboli with lower extremity deep vein thrombosis in a patient diagnosed with both minimal change disease and immunoglobulin M (IgM) kappa monoclonal gammopathy of undetermined significance. No previous report has been published describing venous thromboembolism in a patient with plasma cell dyscrasia and minimal change disease. This case establishes the importance of considering a diagnostic workup for both disorders in patients with venous thromboembolism. Furthermore, venous thromboembolism risk in patients with both of these diseases is significant. Benefits of prophylactic anticoagulation in these patients are still controversial.

Differences in Hospital, Emergency Room and Outpatient Visits Among Adults With and Without Monoclonal Gammopathy of Undetermined Significance

INTRODUCTION

This study evaluated the impact of receiving a monoclonal gammopathy of undetermined significance (MGUS) diagnosis on healthcare utilization from patients at a community-based multispecialty provider organization.

METHODS

A cohort of patients with MGUS (n = 429) were matched on sex, age, and length of enrollment to a cohort of patients without MGUS (n = 1286). Healthcare utilization was assessed: 1-12 months before, 1 month before and after, and 1-12 months after diagnosis/index date. Multivariable conditional Poisson models compared change in utilization of each service in patients with and without MGUS.

RESULTS

During the 2 months around diagnosis/index date, the rates of emergency room, hospital and outpatient visits were higher for patients with MGUS than patients without MGUS. In the year before MGUS diagnosis, the association was still elevated, although attenuated.

CONCLUSION

Understanding the care of MGUS patients is important given that multiple myeloma patients with a pre-existing MGUS diagnosis may have a better prognosis.

Predictive value of 1q21 gain in multiple myeloma is strongly dependent on concurrent cytogenetic abnormalities and first-line treatment

Improved therapies in multiple myeloma (MM) have forced a constant risk stratification update, first Durie-Salmon, then international scoring systems (ISS), next revised-ISS (RISS) including high-risk cytogenetic abnormalities (HRCAs) such as del(17p) and t(4;14), and now R2-ISS including 1q21 gain has been proposed. Predictive value of 1q21 gain by itself or in concurrence with other cytogenetic abnormalities is evaluated in 737 real-world plasma cell neoplasm (PCN) patients under current therapies. Ten-year progression-free survival (10y-PFS) rates for patients with 2, 3 and >3 copies of 1q21 were 72.2%, 42.5% and 43.4% (P<1.1×10^-17). Cox regression analysis confirmed that 1q21 gain was an independent prognostic factor for PFS (HR=1.804, P<0.0001, Harrell C-statistic =0.7779±0.01495) but not for OS (P=0.131). Gain of 1q21 was strongly associated with hypodiploidy (38.8% vs. 7.0%, P=1.3×10^-22), hyperdiploidy (44.1% vs. 16.4%, P=1.6×10^-13), HRCAs (12.6% vs. 3.5%, 1.8×10^-5), IGH breaks (12.3% vs. 2.1%, P=2.1×10^-7) and del(13q) (8.0% vs. 4.0%, P=0.031). In our series, 1q21 gain by itself did not improve RISS predictive capacity in patients either eligible or ineligible for autologous stem cell transplantation (ASCT). However, compared with patients with other 1q21 gains: concurrence with hyperdiploidy improved the prognosis of ASCT-eligible patients from 62.5% to 96.0% 10-year overall-survival (10y-OS, P<0.002); concurrence with hypodiploidy improved the prognosis of ASCT-ineligible patients from 35.7% to 71.0% (P=0.013); and concurrence with del(13q) worsened the prognosis of ASCT-ineligible patients from 12.5% to 53.4% (P=0.035). Gain of 1q21 should be patient-wisely evaluated, irrespective of the RISS, considering its concurrence with other cytogenetic abnormalities and eligibility for ASCT.

Atypical Presentation of Plasma Cell Neoplasm of the Sternum

Multiple myeloma (MM) is a rare plasma cell neoplasm characterized by monoclonal cell infiltration in the bone marrow, which can cause anemia, bone pain, and recurrent infections. Extramedullary myeloma (EM) is a rare clinical presentation with a poor prognosis. It involves the accumulation of clonal plasma cells in soft tissues with a tumor-like appearance, either presenting as a primary (initial) or secondary (relapse) malignancy. We present a case of a 65-year-old male who experienced an abrupt onset of chest pain associated with a localized sternal mass while exercising the day prior to arrival. Chest computed tomography (CT) scan with contrast revealed an expansile lytic lesion around the sternal area. Due to high suspicion for malignancy, a CT-guided core needle biopsy was done, which showed plasma cells with rare Dutcher bodies consistent with MM. Bone marrow smear showed the presence of 70% plasma cells confirming a diagnosis of MM. Early detection of this devastating disease may help improve survival. Therefore, physicians should have a high index of suspicion for MM in older patients with similar clinical presentations.

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.

Proliferation to Apoptosis Tumor Cell Ratio as a Biomarker to Improve Clinical Management of Pre-Malignant and Symptomatic Plasma Cell Neoplasms

Proliferation and apoptosis of neoplastic cells are prognostic biomarkers in plasma cell neoplasms (PCNs). The prognostic capacity of proliferation to apoptosis ratio (Ratio-PA) in the era of immunomodulatory treatments is re-evaluated in 316 gammopathy of undetermined significance (MGUS), 57 smoldering multiple myeloma (SMM), and 266 multiple myeloma (MM) patients. Ratio-PA of 0.77 ± 0.12, 1.94 ± 0.52, and 11.2 ± 0.7 (p < 0.0001) were observed in MGUS, SMM, and MM patients. Ten-year overall survival (10y-OS) rates for patients with low/high Ratio-PA were 93.5%/77.3% p < 0.0001) for MGUS, 82.5%/64.7% (p < 0.05) for SMM, and 62.3%/47.0% (p < 0.05) for MM. For patients with low, intermediate, and high risk, 10y-OS for low/high Ratio-PA were 95.5%/72.9% (p < 0.0001), 74.2%/50.4% (p < 0.0001), and 35.3%/20.0% (p = 0.836), respectively. Ratio-PA was an independent prognostic factor for OS (HR = 2.119, p < 0.0001, Harrell-C-statistic = 0.7440 ± 0.0194) when co-analyzed with sex, age, and standard risk. In patients with Ratio-PA^high, only first-line therapy with VRd/VTd, but not PAD/VCD, coupled with ASCT was associated with high 10y-OS (82.7%). Tumor cell Ratio-PA estimated at diagnosis offers a prognostic biomarker that complements standard risk stratification and helps to guide the clinical management of pre-malignant and symptomatic PCNs. Every effort should be made to provide first-line therapies including VTd or VRd associated with ASCT to patients with Ratio-PA^high at higher risk of progression and death.

[Monoclonal gammopathy of renal significance: consensus of hematologists and nephrologists of Russia on the establishment of nosology, diagnostic approach and rationale for clone specific treatment]

Monoclonal gammopathy of renal significance (MGRS) is a new nosology in modern nephrology and oncohematology. MGRS is defined as kidney injury due to nephrotoxic monoclonal immunoglobulin produced by the B-cell line clone which does not reach the hematological criteria for specific treatment initiation. Monoclonal proteins pathological effects on kidney parenchyma result in irreversible decline of kidney function till the end stage renal disease that in line with the position of International Consensus of hematologists and nephrologists determinates critical necessity for clone specific treatment in patients with MGRS despite the absence of hematological indications for treatment initiation. Main challenge of MGRS in Russian Federation is an inaccessibility of an in-time diagnostic and appropriate treatment for the great majority of patients due to the following reasons: 1) limited knowledge about the MGRS among hematologists and nephrologists; 2) lack of necessary diagnostic resources in most health-care facilities; 3) lack of approved clinical recommendations and medical economic standards for treatment of this pathological entity. Consensus document comprises the opinion of experts leading nephrologists and hematologists of Russian Federation on the problem of MGRS including the incoherence in nosology classification, diagnostics approach and rationale for clone specific treatment. Consensus document is based on conclusions and agreements reached during the conference of leading nephrologists and hematologists of Russia which was held in the framework of symposia Plasma cell dyscrasias and lymphoproliferative diseases: modern approaches to therapy, 1516 of March 2019, Pavlov First Saint Petersburg State Medical University. The present Consensus is intended to define the principal practical steps to resolve the problem of MGRS in Russian Federation that are summarized as final clauses.

Consensus Guidelines on the Diagnosis of Multiple Myeloma and Related Disorders: Recommendations of the Myeloma Canada Research Network Consensus Guideline Consortium

Multiple myeloma (MM) is a plasma cell (PC) malignancy of terminally differentiated B lymphocytes that is typically associated with the secretion of partial and/or complete monoclonal immunoglobulins and a constellation of particular symptoms and signs. MM is a treatable condition, and timely diagnosis is essential to limit or avoid irreversible target-organ damage and to prolong survival. The Myeloma Canada Research Network Consensus Guideline Consortium (MCRN-CGC) proposes national consensus recommendations for the diagnosis of MM and associated PC neoplasms. The focus is on widely available tests but also highlights recent advancements that are important to include in the diagnostic paradigm. By clarifying and updating the required laboratory, radiographic, and bone marrow investigations, the MCRN-CGC hopes to address the needs of Canadian physicians and people living with MM across the country through accurate and timely diagnosis of MM, as well as appropriate initial stratification to improve treatment selection and outcomes. The MCRN-CGC will periodically review the recommendations herein and update as necessary. Recommendations on the therapeutic approaches and associated monitoring of MM will follow.

Maculopathy in Patients with Monoclonal Gammopathy of Undetermined Significance

PURPOSE

To describe clinical findings, laboratory values, and treatment response of patients with monoclonal gammopathy of undetermined significance (MGUS) demonstrating neurosensory macular detachment.

DESIGN

Retrospective case series.

PARTICIPANTS

Seven eyes of 4 patients (3 men and 1 woman; age range, 60-81 years) with neurosensory macular detachment, treatment-resistant submacular fluid, and vitelliform material.

METHODS

We retrospectively reviewed the medical and ocular histories, ocular examination findings, retinal imaging, ocular disease course, and laboratory findings in 4 patients with submacular fluid associated with MGUS.

MAIN OUTCOME MEASURES

Description of the macular findings and treatment courses of 4 patients diagnosed with MGUS maculopathy.

RESULTS

Seven eyes of 4 patients demonstrated neurosensory macular detachment with treatment-resistant submacular fluid and vitelliform material. No eyes demonstrated signs of significant hyperviscosity retinopathy. Fluorescein angiography showed no definite leakage in any involved eye. Laboratory evaluation revealed immunoglobulin G MGUS in all 4 patients. All 4 patients were resistant to treatments aimed at resolving the subretinal fluid, including some combination of anti-vascular endothelial growth factor injections, photodynamic therapy, topical dorzolamide, oral dosing of eplerenone or acetazolamide, or some combination thereof. In 3 patients, MGUS underwent malignant transformation 24 to 144 months after diagnosis, in 1 patient to lymphoplasmacytic lymphoma and in 2 patients to multiple myeloma. The fourth patient showed no evidence of malignancy 8 years after diagnosis.

CONCLUSIONS

Submacular fluid without fluorescein leakage and unresponsive to conventional treatment may suggest an underlying immunoproliferative disorder that we have termed monoclonal gammopathy of macular significance. Given the propensity for monoclonal gammopathy of macular significance to transform into malignant disease in our series, serum protein analysis should be considered in patients with neurosensory macular detachment not attributable to known causes.

Monoclonal gammopathy of undetermined significance

Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant plasma cell dyscrasia that consistently precedes multiple myeloma (MM) with a 1% risk of progression per year. Recent advances have improved understanding of the complex genetic and immunologic factors that permit progression from the aberrant plasma cell clone to MGUS and overt MM. Additional evidence supports bidirectional interaction of MGUS cells with surrounding cells in the bone marrow niche that regulates malignant transformation. However, there are no robust prognostic biomarkers. Herein we review the current body of literature on the biology of MGUS and provide a rationale for the improved identification of high-risk MGUS patients who may be appropriate for novel clinical interventions to prevent progression or eradicate premalignant clones prior to the development of overt MM.

Deciphering the chronology of copy number alterations in Multiple Myeloma

Multiple myeloma (MM) and its precursor condition MGUS are characterized by chromosomal aberrations. Here, we comprehensively characterize the order of occurrence of these complex genomic events underlying MM development using 500 MGUS, and MM samples. We identify hyperdiploid MM (HMM) and non-HMM as genomically distinct entities with different evolution of the copy number alterations. In HMM, gains of 9,15 or 19 are the first and clonal events observed as clonal even at MGUS stage. These events are thus early and may underlie initial transformation of normal plasma cells to MGUS cells. However, CNAs may not be adequate for progression to MM except in 15% of the patients in whom the complex subclonal deletion events are observed in MM but not MGUS. In NHMM, besides the driver translocations, clonal deletion of 13 and 1q gain are early events also observed in MGUS. We combined this information to propose a timeline for copy number alteration.

Monoclonal gammopathy of renal significance: clinical manifestation, pathogenic characteristic and treatment

Monoclonal gammopathy of renal significance (MGRS) is a group of renal disorders caused by a monoclonal immunoglobulin (MIg) secreted by a dangerous plasmatic/B-cell clone hyperplasia through MIg deposition or dysfunction of complement pathway, with increasing risk of progress to end stage renal disease (ESRD) and the underlying hematologic malignancy. The combination of renal biopsy, complete laboratory examination and bone marrow biopsy is an indispensable diagnostic tool for MGRS to identify accurately and unequivocally the pathogenic monoclonal MIg and provide guidance to treatment. Treatment of MGRS is composed of conventional therapy, chemotherapy, and stem cell transplantation to target the underlying clone and eliminate the noxious MIg on the basis of clinical data of some retrospective studies and a small amount of prospective trial. In addition, it is worthwhile point out assessment of therapeutic effect is significantly relevant for renal and overall prognosis. Thus, by comprehensively analyzing the clinical manifestations and pathogenic characteristic of MGRS, early recognition and prompt treatment can improve the prognosis and prevent post-translation recurrence with multidisciplinary cooperation.

Hepatitis E: an underestimated emerging threat

Hepatitis E virus (HEV) is the most common cause of viral hepatitis in the world. It is estimated that millions of people are infected every year, resulting in tens of thousands of deaths. However, these estimates do not include industrialized regions and are based on studies which employ assays now known to have inferior sensitivity. As such, this is likely to represent a massive underestimate of the true global burden of disease. In the developing world, HEV causes large outbreaks and presents a significant public-health problem. Until recently HEV was thought to be uncommon in industrialized countries, and of little relevance to clinicians in these settings. We now know that this is incorrect, and that HEV is actually very common in developed regions. HEV has proved difficult to study in vitro, with reliable models only recently becoming available. Our understanding of the lifecycle of HEV is therefore incomplete. Routes of transmission vary by genotype and location: endemic regions experience large waterborne epidemics, while sporadic cases in industrialized regions are zoonotic infections likely spread via the food chain. Both acute and chronic infection has been observed, and a wide range of extrahepatic manifestations have been reported. This includes neurological, haematological and renal conditions. As the complete clinical phenotype of HEV infection is yet to be characterized, a large proportion of cases go unrecognized or misdiagnosed. In many cases HEV infection does not feature in the differential diagnosis due to a lack of knowledge and awareness of the disease amongst clinicians. In combination, these factors have contributed to an underestimation of the threat posed by HEV. Improvements are required in terms of recognition and diagnosis of HEV infection if we are to understand the natural history of the disease, improve management and reduce the burden of disease around the world.

Biological determinants of health disparities in multiple myeloma

Multiple myeloma is a rare plasma cell cancer, and incidence rates among patients of African descent are about twice those among patients of European descent. Rates of multiple myeloma vary among different populations, but the reasons for the racial disparities in multiple myeloma are largely unknown. Epidemiology has identified risk factors for multiple myeloma including race, advanced age, gender, family history, and exposure to different genetic toxins including radiation. Race and ancestry play a large role in predicting the risk for multiple myeloma, yet there exists a paucity of literature that explores the molecular contribution of race and ancestry to disease. In this review, we describe the relevant literature that describes the observed racial differences according to distinct tumor immunobiological and ancestral differences in populations.

Advances in the understanding of IgM monoclonal gammopathy of undetermined significance

Among monoclonal gammopathies of undetermined significance (MGUSs), the immunoglobulin M (IgM) MGUS subtype stands as a unique entity and plays a pivotal role as a pre-malignant condition for multiple B-cell non-Hodgkin lymphomas, most notably Waldenström macroglobulinemia (WM). A relationship between IgM MGUS and WM has been proposed for decades. However, insight regarding the pathobiology of these two conditions improved significantly in recent years, strengthening the hypothesis that WM and IgM MGUS are different stages of the same disease. Therefore, the understanding of IgM MGUS and that of WM are interconnected and advances in one will likely impact the other. Furthermore, IgM MGUS has been more commonly recognized as the underlying etiology of IgM-related disorders. In this review, we explore recent advances in the understanding of the pathobiology of IgM MGUS and WM and the treatment of common IgM-related disorders.

Smoldering Multiple Myeloma: Emerging Concepts and Therapeutics

Smoldering multiple myeloma (SMM) is a pre-malignant condition with an inherent risk for progression to multiple myeloma (MM). The 2014 IMWG guidelines define smoldering multiple myeloma as a monoclonal gammopathy disorder with serum monoclonal protein (IgG or IgA) ≥30 g/L or urinary monoclonal protein ≥500 mg per 24 h and/or clonal bone marrow plasma cells 10-60 % without any myeloma-defining events or amyloidosis. The risk for progression of SMM to MM vary based on clinical, laboratory, imaging, and molecular characteristics. Observation, with periodic monitoring is the current standard of care for SMM. Over last few years, research advances in SMM have led to the delineation of newer risk factors for progression and identification of a "high-risk" group that would potentially benefit from early treatment. This review focuses on advances in the SMM risk-stratification model and recent clinical trials in this patient population.

Hepatitis E virus: Infection beyond the liver?

Hepatitis E virus (HEV) infections are not limited to the liver but may also affect other organs. Several diseases, including Guillain-Barré syndrome, neuralgic amyotrophy, glomerulonephritis, cryoglobulinemia, pancreatitis, lymphoma, thrombopenia, meningitis, thyroiditis and myocarditis have been observed in the context of hepatitis E. To date, the definite pathophysiological links between HEV and extrahepatic manifestations are not yet established. However, it is suggested that HEV infection might be causative based on serological studies, case series, in vitro data and animal models. In particular, neuronal and renal diseases as well as pancreatitis seem to be caused by HEV, while a causative relationship between HEV and other diseases is more doubtful. Either direct cytopathic tissue damage by extrahepatic replication, or immunological processes induced by an overwhelming host immune response, are possible origins of HEV-associated extrahepatic manifestations. Hepatologists should be aware of the possibility that acute or chronically HEV-infected patients could develop extrahepatic manifestations. Neurologists, nephrologists, rheumatologists and other groups of physicians should consider HEV infection as a potential differential diagnosis when observing one of the diseases described in this review. Ribavirin and steroids have been used in small groups of patients with extrahepatic manifestations of HEV, but the efficacy of these drugs still needs to be verified by large, multicenter studies. This article comprehensively reviews the published literature regarding HEV and extrahepatic manifestations. We discuss the probability of specific extrahepatic diseases being caused by previous or ongoing HEV infection, and summarize the published knowledge about antiviral treatment in extrahepatic disorders.

History of autoimmune disease is associated with impaired survival in multiple myeloma and monoclonal gammopathy of undetermined significance: a population-based study

Multiple myeloma (MM) is a plasma cell disorder preceded by monoclonal gammopathy of undetermined significance (MGUS). Incidence of MM and MGUS is higher among patients with autoimmune disease. The aim of this study was to determine whether a history of autoimmunity has an impact on survival in MM and MGUS. Using high-quality national Swedish registries, we identified 8367 patients with MM, 18,768 patients with MGUS, and 110,251 matched control subjects, and obtained information on previous autoimmune disease in patients and controls. Cox regression was used to calculate hazard ratios (HRs) for overall survival with 95 % confidence intervals (CIs). In patients with MM and a prior autoimmune disease, the risk of death was significantly increased, HR = 1.2 (95 % CI 1.2-1.3) compared to MM patients with no history of autoimmunity. In MGUS patients, a prior autoimmune disease was associated with a significantly 1.4-fold elevated risk of death (95 % CI 1.3-1.4). When analyzing different types of autoimmune diseases, a history of ulcerative colitis had a stronger impact on survival in MM than in controls. Our findings that a history of autoimmune disease has a negative impact on survival in MM and MGUS could be due to shared underlying common genetic factors, or that patients with a history of autoimmunity develop more severe cases of MM and MGUS, or cumulative comorbidity in the individual. Our results suggest that more attention should be paid to comorbidity as a prognostic factor in MGUS and MM, and underlines the need for studies aimed at tailoring therapy according to comorbidity.

Immunotherapeutic Biologic Agents in Autoimmune and Autoinflammatory Diseases

In recent decades, innovative strategies to treat patients with inflammatory, immunologically based diseases have advanced in concert with our increased understanding of molecular immunology. Recognition of the spectrum and pathophysiology of autoimmune and autoinflammatory disorders has allowed for the development of cutting-edge therapies for such patients. In this review, key immunotherapeutic approaches for treating inflammatory autoimmune disorders, such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), as well as genetic autoinflammatory diseases, such as cryopyrin associated periodic syndromes, are addressed. Indications, risks and additional considerations in the use of these agents are reviewed.

The Immunotyping Distribution of Serum Monoclonal Paraprotein and Environmental Impact on Multiple Myeloma (MM) and Monoclonal Gammopathy of Uncertain Significance (MGUS) in Taiwan: A Medical Center-Based Experience

BACKGROUND

Whether ambient exposure to environmental pollutants leads to hematopoietic malignancies such as multiple myeloma (MM) remains to be ascertained. Therefore, we aimed to investigate the immunotyping distribution of serum monoclonal paraprotein and the environmental influence on MM and monoclonal gammopathy of uncertain significance (MGUS) in the Taiwanese population.

MATERIALS AND METHODS

Serum protein electrophoresis with immunosubtraction by the capillary zone electrophoresis method was performed as primary screening for MM and MGUS. Clinical, pathological, and residence data of patients were also obtained.

RESULTS

From August, 2013 to June, 2015, a total of 327 patients underwent serum protein electrophoresis with immunosubtraction. Among these, 281 demonstrated no remarkable findings or non-malignant oligoclonal gammopathy, 23 were detected to have MGUS, 18 were identified as MM, and a further 5 were found as other malignancies. The most frequent immunotyping distribution of serum monoclonal paraprotein was IgG kappa (54.3%, n=25), followed by IgA lambda (15.2%, n=7) and IgG lambda (10.9%, n=5) in subjects with gammopathy. Additionally, it was shown that the elderly (OR: 4.61, 95% CI: 1.88-11.30, P<0.01) and males (OR: 2.04, 95% CI: 1.04-4.02, P=0.04) had significantly higher risk of developing MM and MGUS. There was no obvious impact of environmental factors on the health risk of MM and MGUS evolution (OR: 0.77, 95% CI: 0.40-1.50, P=0.49).

CONCLUSIONS

The most frequent immunotyping distribution of serum monoclonal paraprotein included IgG kappa, IgA lambda and IgG lambda in MM and MGUS in the Taiwanese population. The elderly and male subjects are at significantly higher risk of MM and MGUS development, but there was no obvious impact of environmental factors on risk.

The potential diagnostic power of extracellular vesicle analysis for multiple myeloma

Multiple myeloma (MM) is a hematologic malignancy of plasma cells (PCs). In the United States, MM accounts for approximately 1% of all diagnoses and 2% of all cancer-related deaths. Although MM is a treatable disease, most patients eventually relapse, and despite the development of numerous treatment options it is still considered incurable. Mechanisms of communication between MM-PCs and bone marrow microenvironment, including cell-cell contacts and release of pro-survival factors, promote cancer cell survival and drug resistance. Recently, the importance of extracellular vesicles (EVs) as mechanisms of communication between MM cells and other cells in the microenvironment has been reported. In this review, the authors provide the update on the biology and clinical aspects of EVs in MM.

Monoclonal Gammopathy in HIV-1-Infected Patients: Factors Associated With Disappearance Under Long-Term Antiretroviral Therapy

OBJECTIVE

Monoclonal gammopathies (MGs) associated with HIV infection are frequent but their evolution and significance are uncertain in this population at high risk of lymphoproliferative disorder. Our aim was to describe the long-term evolution of MG in HIV-infected subjects under antiretroviral therapy.

METHODS

Retrospective study of HIV-1-infected adults, with a monoclonal (M) protein detected by serum protein electrophoresis and confirmed by immunofixation. Logistic regression was used to analyze factors associated with peak disappearance.

RESULTS

Between September 1997 and November 2012, 1219 serum protein electrophoreses were performed on our HIV cohort, and 137 (11.3%) MGs were detected. Seventy-seven subjects met the inclusion criteria: 68% male, median age 41 years, 47% AIDS stage, median CD4 count 237 per cubic millimeter, 81% uncontrolled HIV infection with HIV viral load over 400 copies per milliliter, 32% chronic hepatitis C, and 9% chronic hepatitis B. Eighteen subjects were not included because of previous or concomitant hemopathy. With a median follow-up of 6.8 years (interquartile range, 3.9-9.1), 66.2% of subjects showed a peak disappearance. In multivariate analysis, MG disappearance was associated with HIV virologic control (odds ratio, 5.98; 95% confidence interval: 1.63 to 21.87; P = 0.007) and the absence of hepatitis C virus replication at the end of follow-up (odds ratio, 10.16; 95% confidence interval: 2.36 to 43.69; P = 0.002). One subject developed a myeloma 3 years after the diagnosis of an IgA kappa MG.

CONCLUSIONS

MG associated with HIV infection concerned a young population and had favorable evolution on antiretroviral therapy in most cases. M protein disappearance was associated with HIV virologic control and the absence of chronic hepatitis C virus.

Challenges of measuring monoclonal proteins in serum

The measurement of monoclonal protein (M-protein) is vital for stratifying risk and following individuals with a variety of monoclonal gammopathies. Direct measurement of the M-protein spike by electrophoresis and immunochemical measurements of specific isotypes or free light chains pairs has provided useful information about the quantity of M-protein. Nonetheless, both traditional electrophoresis and immunochemical methods give poor quantification with M-proteins smaller than 10 g/L (1 g/dL) when in the presence of polyclonal immunoglobulins that co-migrate with the M-protein. In addition, measurements by electrophoresis of M-proteins migrating in the β- and α-regions are contaminated by normal serum proteins in those regions. The most precise electrophoretic method to date for quantification involves exclusion of the polyclonal immunoglobulins by using the tangent skimming method on electropherograms, which provides a 10-fold improvement in precision. So far, however, tangent measurements are limited to γ migrating M-proteins. Another way to improve M-protein measurements is the use of capillary electrophoresis (CE). With CE, one can employ immunosubtraction to select a region of interest in the β region thereby excluding much of the normal proteins from the M-protein measurement. Recent development of an immunochemical method distinguishing heavy/light chain pairs (separately measuring IgGK and IgGL, IgAK and IgAL, and IgMK and IgML) provides measurements that could exclude polyclonal contaminants of the same heavy chain with the uninvolved light chain type. Yet, even heavy/light results contain an immeasurable quantity of polyclonal heavy/light chains of the involved isotype. Finally, use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) looms on the horizon as a means to provide more consistent and sensitive measurements of M-proteins.

Laboratory guidelines for the diagnosis and follow-up of patients with monoclonal gammopathies

We present guidelines from the Immunochemistry group of the Spanish Society for Immunology that are designed to provide a practical tool for the diagnosis and follow-up of monoclonal gammopathies. We review the clinical and analytical features of various monoclonal gammopathies, international consensus guidelines and techniques used to detect and follow-up monoclonal components.

Asymptomatic monoclonal gammopathies

Monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM) represent the earlier phases of plasma cell dyscrasias. Their definition is based on absence of end-organ damage with presence of a malignant clone that grows in the bone marrow. They share, as a common feature, the risk of progression to a symptomatic disease. MGUS progression risk is approximately 1% per year, and SMM has a risk of progression of 10% for the first 5 years which tapers off over time. The main purpose of identification of these earlier phases of the plasma cell dyscrasia was to identify patients who do not warrant treatment with chemotherapy, in whom the risk of treatment outweighs the benefit. Over the years, the definitions have not been modified to incorporate developments in imaging (magnetic resonance or positron emission and computed tomography), or genomics to identify patients at highest risk of progression within 2 years, where wait and watch might not be an appropriate option. In the absence of such definition, patients who have only a 50% chance of progression within 2 years are being offered therapy, which might also not be an optimal approach. In this review, we provide an overview of the definition, current prognostic factors, and risk stratifications in asymptomatic gammopathies, and discuss clinical trial outcomes in high-risk SMM.

SAMSN1 is a tumor suppressor gene in multiple myeloma

Multiple myeloma (MM), a hematological malignancy characterized by the clonal growth of malignant plasma cells (PCs) in the bone marrow, is preceded by the benign asymptomatic condition, monoclonal gammopathy of undetermined significance (MGUS). Several genetic abnormalities have been identified as critical for the development of MM; however, a number of these abnormalities are also found in patients with MGUS, indicating that there are other, as yet unidentified, factors that contribute to the onset of MM disease. In this study, we identify a Samsn1 gene deletion in the 5TGM1/C57BL/KaLwRij murine model of myeloma. In addition, SAMSN1 expression is reduced in the malignant CD138 + PCs of patients with MM and this reduced expression correlates to total PC burden. We identify promoter methylation as a potential mechanism through which SAMSN1 expression is modulated in human myeloma cell lines. Notably, re-expression of Samsn1 in the 5TGM1 murine PC line resulted in complete inhibition of MM disease development in vivo and decreased proliferation in stromal cell–PC co-cultures in vitro. This is the first study to identify deletion of a key gene in the C57BL/KaLwRij mice that also displays reduced gene expression in patients with MM and is therefore likely to play an integral role in MM disease development.

Renal involvement in monoclonal gammopathy

Monoclonal gammopathy is produced by neoplastic or non-neoplastic expansion of a clone of plasma cells or B lymphocytes. Monoclonal gammopathy of unknown significance is characterized by low levels of the monoclonal protein and a relatively small population of clonal lymphocytes or plasma cells in the bone marrow. In these cases, the patient is asymptomatic with no evidence of overt myeloma or lymphoma. The abnormal serum protein may be present as a complete immunoglobulin molecule or may consist of ≥1 of its components such as light chains or heavy chains. These proteins may cause a variety of diseases in various tissues and organs, of which the kidney appears to be the most vulnerable. Renal involvement in monoclonal gammopathy may occur as part of a generalized disease such as amyloidosis, immunoglobulin deposition disease, and cryoglobulinemia. In addition, there may be evidence of kidney damage by processes which are renal specific. These include light chain proximal tubulopathy, light chain cast nephropathy, and a variety of glomerulopathies encompassing a wide spectrum of disease patterns.

Multiple myeloma

This article presents a review of multiple myeloma, precursor states, and related plasma cell disorders. The clinical roles of fluorodeoxyglucose PET/computed tomography (CT) and the potential to improve the management of patients with multiple myeloma are discussed. The clinical and research data supporting the utility of PET/CT use in evaluating myeloma and other plasma cell dyscrasias continues to grow.

When an Analytical Interference Is a Useful Diagnostic Tool: Finding Monoclonal Gammopathies in Routine Analysis

BACKGROUND

The daily productivity of a clinical laboratory depends on the large number of interferences that affect analytical accuracy. Obviously, they have always been considered as a very important aspect to keep accuracy under control. Nevertheless, we wondered if this aspect would be beneficial. In this article, we propose a method for finding monoclonal gammopathies that are based on the fact that the presence of paraprotein in the sample may interfere with routine laboratory assays, specifically, with the quantification of uric acid and conjugated bilirubin.

METHODS

Over a 5-month period, we evaluated 18,278 sera samples of patients from primary care. None of them were suspected of having plasma cell dyscrasias (not observed hypercalcemia, renal failure, anemia, and/or lytic bone lesions). Although biochemical findings suggested paraprotein interference, we carried out serum capillary electrophoresis (CE) and quantification of immunoglobulins and serum-free light chains (SFLCs). We also confirmed the results obtained by performing the corresponding immunofixation electrophoresis (IFE). Flow cytometry analyses were conducted for immunophenotypic characterization of plasma cells from these patients.

RESULTS

The proposed detection method allowed us to identify eight patients with previously undiagnosed monoclonal gammopathy.

CONCLUSIONS

The results show that it is possible to use analytical interference for diagnostic purposes, and most importantly, almost all cases were identified at an early stage of the disease, when associated clinical manifestations were not yet observed.

Proliferative glomerulonephritis associated with monoclonal immune deposits: A case report and review of literature

Proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID) is a newly recognized entity caused by monoclonal deposition of IgG. PGNMID resembles immune complex glomerulonephritis (GN) on light and electron microscopy. The monotypic immunoglobulin deposits seen on immunofluorescence (IF) clinches the diagnosis. We report a case of proliferative GN associated MGRS and review the relevant literature. The patient had significant proteinuria and elevated serum creatinine. The renal biopsy showed proliferative GN with focal crescents and monoclonal immune deposits confirming a diagnosis of PGNMID. Serum work up showed no monoclonal proteins. Proliferative GN as a manifestation of a monoclonal gammopathy needs to be borne in mind especially in renal biopsies of older patients.

The interference of monoclonal antibodies with laboratory diagnosis: clinical and diagnostic implications

Diagnostic test interference is due to the presence of material that falsely changes an analytic test result. The development of monoclonal antibodies is discussed with focus on their extensive use as both therapeutic and diagnostic agents. In this review the interference of monoclonal antibodies with laboratory test methods and the potential impact on clinical care is addressed. Recognition of the types of interference, endogenous and exogenous, and the varied mechanisms by which monoclonal antibodies may cause interference are discussed in this report. Review of the literature identifies cases which exemplify the issues facing laboratorians and clinicians and describe the impact on patients. Approaches to reducing and eliminating sources of interference are also addressed. Education of ordering clinicians concerning the possibility of interference in at-risk patients is key in limiting the impact on care. Laboratorians and medical practitioners should be cognizant of the risk of interference to avoid incorrect management of patients.

Pathogenesis of renal failure in multiple myeloma: any role of contrast media?

The spectrum of kidney disease-associated monoclonal immunoglobulin and plasma cell malignancies is remarkably broad and encompasses nearly all nephropathologic entities. Multiple myeloma with kidney impairment at presentation is a medical emergency since the recovery of kidney function is associated with survival benefits. In most cases, kidney impairment may be the first clinical manifestation of malignant plasma cell dyscrasias like multiple myeloma and light chain amyloidosis. Multiple myeloma per se cannot be considered a main risk factor for developing acute kidney injury following intravascular administration of iodinated contrast media. The risk is increased by comorbidities such as chronic kidney disease, diabetes, hypercalcemia, dehydration, and use of nephrotoxic drugs. Before the administration of contrast media, the current recommended laboratory tests for assessing kidney function are serum creatinine measurement and the estimation of glomerular filtration rate by using the CKD-EPI equation. The assessment of Bence Jones proteinuria is unnecessary for evaluating the risk of kidney failure in patients with multiple myeloma, since this test cannot be considered a surrogate biomarker of kidney function.

[Multiple myeloma]

Multiple myeloma (MM) is a cancer originating from terminally differentiated B lymphocytes, the plasma cells and is classified as a B cell non-Hodgkin lymphoma. As clonal plasma cells secrete immunoglobulin molecules (lacking antigenic specificity), an "M component" can incidentally be detected. Besides intact immunoglobulin molecules, free light chains can be produced. Although there is no specific treatment for monoclonal gammopathy of undetermined significance (MGUS), which is the defined as the presence of clonal bone marrow plasma cells and low levels (serum and/or urine) of the M component, it should be followed up in affected individuals. The symptoms of MM are numerous and often nonspecific. Diagnosis includes the quantification of monoclonal proteins in serum and urine, blood count, electrolytes and renal function, imaging of the skeleton and bone marrow puncture. The cornerstone of therapy includes melphalan- or cyclophosphamide-based regimens incorporating one of the "novel drugs" (i.e. bortezomib, thalidomide, or lenalidomide).

IgM Myeloma or Waldenstrom's Macroglobulinemia Is the Big Question?

Although critical from therapeutic and prognostic perspectives, differentiating IgM Myeloma (MM) from Waldenstrom's macroglobulinemia (WM) is fraught with failure. WM can usually be distinguished from IgM MM by the lymphoplasmacytic versus pure plasmacytic morphology, absent versus present lytic bone lesions, and immunophenotypic findings. However, all these features have their own limitations; hence, it requires constant vigilance and periodic re-evaluation. Here we describe a case of a 70-year-old woman initially diagnosed as smoldering IgM MM, who eventually turned out to have WM.

Discovering the meaning of monoclonal gammopathy of undetermined significance: current knowledge, future challenges

Monoclonal gammopathy of undetermined significance (MGUS) is a non malignant plasma cell disorder with a relatively low risk of progression to Multiple Myeloma (MM) and to related Plasma cells disordes (lymphoplasmacellular neoplasms, Waldenstrom Macroglobulinemia or light chain amyloidosis). It is a quite common finding, especially in the population above the age of 50 and it can also present in association with many non malignant conditions. Differential diagnosis of symptomatic and asymptomatic forms is the determinant for starting therapy. Over the last few years many advances in the understanding of the biology of MGUS, together with large epidemiological studies, allowed to define risk models to estimate the risk of progression to MM according to MGUS isotype and, more recently, to peculiar flow cytometry findings. The goal of many recent studies aims at evaluating individual patients and their overall risk of progression, the detection of early signs of progression and the development of timely treatment strategies.

Serum-free light-chain assay: clinical utility and limitations

In the last decade, the introduction of the serum-free light-chain (sFLC) assay has been an important advance in the diagnosis and management of plasma cell dyscrasias, particularly monoclonal light-chain diseases. The immunoassay was developed to detect free light chains in serum by using anti-FLC antibodies which specifically recognised epitopes on light chains that were 'hidden' in intact immunoglobulins. Since its introduction in 2001, there have been several publications in the English language literature discussing the clinical utility as well as analytical limitations of the sFLC assay. These studies have highlighted both positive and negative aspects of the assay particularly with regard to its sensitivity and specificity and the technical challenges that can affect its performance. The contribution and significance of the sFLC assay in the management of light-chain myeloma, primary amyloid light-chain (AL) amyloidosis and non-secretory myeloma are well recognised and will be addressed in this review. The aim of this article is to also review the published literature with a view to providing a clear understanding of its utility and limitations in the diagnosis, prognosis and monitoring of plasma dyscrasias including intact immunoglobulin multiple myeloma (MM) and monoclonal gammopathy of unknown significance (MGUS). The increasing interest in using this assay in other haematological conditions will also be briefly discussed.

Monoclonal gammopathy of undetermined significance and risk of lymphoid and myeloid malignancies: 728 cases followed up to 30 years in Sweden

In 728 Swedish cases of monoclonal gammopathy of undetermined significance (MGUS), followed up to 30 years (median, 10 years), we estimated the cumulative risk of hematologic disorders originating from lymphoid and myeloid lineages. Using Cox regression models, we examined associations of demographic and laboratory factors with progression and determined the discriminatory power of 3 prediction models for progression. Eighty-four MGUS cases developed a lymphoid disorder, representing a cumulative risk of 15.4%. Multiple myeloma (MM) occurred in 53 patients, and the 30-year cumulative risk was 10.6%; an ∼0.5% annual risk. Three factors were significantly associated with progression: abnormal free light-chain (FLC) ratio (<0.26 or >1.65), M-protein concentration (≥1.5 g/dL), and reduction of 1 or 2 noninvolved immunoglobulin isotype levels (immunoparesis). A prediction model with separate effects for these 3 factors and the M-protein isotype had higher discriminatory power than other models, although the differences were not statistically significant. The 30-year cumulative risk for myeloid malignancies was <2%. Our study confirms that abnormal FLC ratio and M-protein concentration >1.5 g/dL, factors previously considered by Mayo Clinic researchers, are predictors for MM progression and suggests that separate consideration of immunoparesis and the Mayo Clinic risk factors could improve identification of MGUS patients at high risk for progression.

[Smoldering multiple myeloma]

Smoldering multiple myeloma (SMM) is an asymptomatic plasma cell neoplasia, characterized by monoclonal plasma cell proliferation in the absence of end-organ damage, but with a high risk of progression to multiple myeloma. It has therefore to be distinguished from monoclonal gammapathy of undetermined significance (MGUS), which has a much lower risk of progression, but also from multiple myeloma, which remains an incurable disease and requires a specific treatment. The critical question in the management of SMM is whether an early therapeutic strategy could help delaying the progression to multiple myeloma, in order to lower the risk of serious complications related to this progression, or even to cure the disease. This early treatment could not be proposed to all SMM patients, who are indeed asymptomatic, and in whom the risk of toxicity could make it difficult to justify the potential benefit obtained. The challenge is to target early at diagnosis SMM patients with a high risk of progression, using available routine tests sufficiently reliable to warrant the therapeutic sanction which relies on it. Today however, apart from randomized studies, recommendations are to maintain therapeutic abstention in SMM patients.