Monoclonal gammopathies of undetermined significance: a review

Molecular Characterization of Waldenstrom's Macroglobulinemia Reveals Frequent Occurrence of Two B-Cell Clones Having Distinct IgH VDJ Sequences

PURPOSE

Malignant B lineage cells in Waldenstrom's macroglobulinemia (WM) express a unique clonotypic IgM VDJ. The occurrence of biclonal B cells and their clonal relationships were characterized.

EXPERIMENTAL DESIGN

Bone marrow and blood from 20 WM patients were analyzed for clonotypic VDJ sequences, clonal B-cell frequencies, and the complementary determining region 3 profile.

RESULTS

Two different clonotypic VDJ sequences were identified in 4 of 20 WM. In two cases, partner clones had different VDJ rearrangements, with one clonotypic signature in bone marrow and a second in blood. For both cases, the bone marrow clone was hypermutated, whereas the blood clone was germ line or minimally mutated. In two other cases, partner clones shared a common VDJ rearrangement but had different patterns of somatic mutations. They lacked intraclonal diversity and were more abundant in bone marrow than in blood. VDJ mutation profiles suggested they arose from a common IgM progenitor. Single-cell analysis in one case indicated the partner clones were reciprocally expressed, following rules of allelic exclusion.

CONCLUSIONS

The existence of two B-cell clones having distinct VDJ sequences is common in WM, suggesting that frequent transformation events may occur. In two cases, the partner clones had distinct tissue distributions in either blood or bone marrow, were of different immunoglobulin isotypes, and in one case exhibited differential response to therapy. The contributions of each clone are unknown. Their presence suggests that WM may involve a background of molecular and cellular events leading to emergence of one or more malignant clones.

CKS1B, overexpressed in aggressive disease, regulates multiple myeloma growth and survival through SKP2- and p27Kip1-dependent and -independent mechanisms

Overexpression of CKS1B, a gene mapping within a minimally amplified region between 153 to 154 Mb of chromosome 1q21, is linked to a poor prognosis in multiple myeloma (MM). CKS1B binds to and activates cyclin-dependent kinases and also interacts with SKP2 to promote the ubiquitination and proteasomal degradation of p27(Kip1). Overexpression of CKS1B or SKP2 contributes to increased p27(Kip1) turnover, cell proliferation, and a poor prognosis in many tumor types. Using 4 MM cell lines harboring MAF-, FGFR3/MMSET-, or CCND1-activating translocations, we show that lentiviral delivery of shRNA directed against CKS1B resulted in ablation of CKS1B mRNA and protein with concomitant stabilization of p27(Kip1), cell cycle arrest, and apoptosis. Although shRNA-mediated knockdown of SKP2 and forced expression of a nondegradable form of p27(Kip1) (p27(T187A)) led to cell cycle arrest, apoptosis was modest. Of importance, while knockdown of SKP2 or overexpression of p27(T187A) induced cell cycle arrest in KMS28PE, an MM cell line with biallelic deletion of CDKN1B/p27(Kip1), CKS1B ablation induced strong apoptosis. These data suggest that CKS1B influences myeloma cell growth and survival through SKP2- and p27(Kip1)-dependent and -independent mechanisms and that therapeutic strategies aimed at abolishing CKS1B function may hold promise for the treatment of high-risk disease for which effective therapies are currently lacking.

Peripheral nervous system involvement in patients with cancer

Involvement of the peripheral nervous system (PNS) is common in patients with cancer and any part, including motor neurons, sensory ganglia, nerve roots, plexuses, cranial and peripheral nerves, and neuromuscular junctions, can be affected. Different mechanisms can initiate damage associated with cancer-related PNS disorders. These include tumour infiltration, toxicity of treatments, metabolic and nutritional perturbations, cachexia, virus infections, and paraneoplastic neurological syndromes. The type of cancer, lymphoma, or solid tumour is a further determinant of a PNS disorder. In this Review we discuss the different causes and mechanisms of disorders of the PNS in patients with cancer and we will focus on their assessment and diagnosis.

Multiple myeloma: A review of the epidemiologic literature

Multiple myeloma, a neoplasm of plasma cells, accounts for approximately approximately 15% of lymphatohematopoietic cancers (LHC) and 2% of all cancers in the US. Incidence rates increase with age, particularly after age 40, and are higher in men, particularly African American men. The etiology is unknown with no established lifestyle, occupational or environmental risk factors. Although several factors have been implicated as potentially etiologic, findings are inconsistent. We reviewed epidemiologic studies that evaluated lifestyle, dietary, occupational and environmental factors; immune function, family history and genetic factors; and the hypothesized precursor, monoclonal gammopathies of undetermined significance (MGUS). Because multiple myeloma is an uncommon disease, etiologic assessments can be difficult because of small numbers of cases in occupational cohort studies, and few subjects reporting exposure to specific agents in case-control studies. Elevated risks have been reported consistently among persons with a positive family history of LHC. A few studies have reported a relationship between obesity and multiple myeloma, and this may be a promising area of research. Factors underlying higher incidence rates of multiple myeloma in African Americans are not understood. The progression from MGUS to multiple myeloma has been reported in several studies; however, there are no established risk factors for MGUS. To improve our understanding of the causes of multiple myeloma, future research efforts should seek the causes of MGUS. More research is also needed on the genetic factors of multiple myeloma, given the strong familial clustering of the disease.

Monoclonal gammopathy of undetermined significance

Significant advances have been made in our understanding of the natural history, pathogenesis, mechanisms of progression and prognosis of monoclonal gammopathy of undetermined significance (MGUS). Although the overall incidence of MGUS progression is 1 per year, it is now possible to more accurately predict the risk of progression based on a new risk-stratification model. However, it is still hard to design chemopreventive trials given that the absolute risk of progression per year is low, even in the high-risk group. Therefore, further improvements in estimating the risk of progression are needed. Roughly 50% of MGUS may originate from primary translocation events at the heavy-chain immunoglobulin locus at chromosome 14q32. In most of the remaining MGUS patients, the initiating event is associated with genomic instability that results in hyperdiploidy of certain odd numbered chromosomes. Cytogenetically distinct subtypes of MGUS may carry significant differences in the risk of progression to malignancy. New markers, such as measures of bone marrow angiogenesis and circulating plasma cells may be additional prognostic factors. A better understanding of the mechanisms underlying the transition of normal plasma cells to the MGUS phenotype, and the transition of MGUS to myeloma or related malignancy, will help identify new risk factors for progression and new targets for chemopreventive interventions.

A patient with paroxysmal nocturnal hemoglobinuria, T cell large granular lymphocyte clonal expansion, and monoclonal gammopathy of undetermined significance

Paroxysmal nocturnal hemoglobinuria (PNH) has been described in association separately with T cell large granular lymphocyte (LGL) clonal expansions and plasma cell dyscrasias. We describe a patient with anemia related to hemolytic PNH, with concurrent T cell LGL oligoclonal expansion and IgG lambda monoclonal gammopathy of undetermined significance. Peripheral blood flow cytometry revealed decreased expression of CD55 and CD59 on erythrocytes and decreased expression of CD55 and CD66 on neutrophils. An LGL population was present in the peripheral blood and was characterized as oligoclonal by polymerase chain reaction-based analysis of the T cell receptor gamma-chain variable region. Serum protein electrophoresis with immunofixation showed a low level IgG lambda monoclonal protein. We describe the diagnostic evaluation of this patient and provide a brief review of the reported associations among PNH, LGL clonal expansion, and monoclonal gammopathy.

Systemic capillary leak syndrome associated with compartment syndrome and rhabdomyolysis

Systemic capillary leak syndrome (SCLS) is a rare disorder characterized by recurrent spontaneous episodes of hypovolaemic shock due to marked plasma shifts from the intravascular to the extravascular space. This presents as the characteristic triad of hypotension, haemoconcentration and hypoalbuminemia often with an associated monoclonal gammopathy. We describe a patient with SCLS who required aggressive fluid resuscitation and emergency fasciotomies for compartment syndrome with rhabdomyolysis. At presentation the patient was considered to have severe erythrocytosis and was therefore initially referred to a haematologist, which appears to be a frequent sequence of presentation for patients with SCLS. This patient also highlights the importance of muscle compartment pressure monitoring during volume resuscitation in patients with SCLS.

Investigation of monoclonal gammopathy of undetermined significance: a single-centre study

Summary The main characteristic of monoclonal gammopathies (MG) is the presence of an increased amount of both electrophoretically and immunologically homogeneous immunoglobulins (M component). According to the WHO classification, monoclonal gammopathies are classified among the non-Hodgkin's lymphomas as 'plasma cell dyscrasias'. The unknown behaviour state, so-called MGUS (monoclonal gammopathy of undetermined significance), is distinguished from the malignant diseases. We investigated the frequency and features of MG and MGUS by reviewing the serum immunochemistry protein analyses between 1998 and 2004. Among 18,642 analyses, MG was found in 1,983 cases (10.39%) derived from one or more samples of 416 patients. Case histories of 340 patients were analysed. A malignant lymphoproliferative disease was proved in 171 cases, while in 169 cases the behaviour of the gammopathy was unknown. In 65 cases, the disease was possibly not related to MG. Mean follow-up time of the 65 patients with MGUS was 42 (9-81) months. During the follow-up period seven patients progressed into a malignant lymphoproliferative disorder-- mean probability of the malignant transformation was 3.07%/year and it occurred more frequently in the presence of immunoglobulin A isotype. There was no correlation between the progression of the disease and other laboratory findings. Besides the analyses of MG-related diseases, we focus on the malignant transformation of MGUS and on the importance of regular clinical and laboratory control examinations.

Frequent gain of chromosome band 1q21 in plasma-cell dyscrasias detected by fluorescence in situ hybridization: incidence increases from MGUS to relapsed myeloma and is related to prognosis and disease progression following tandem stem-cell transplantation

Using fluorescence in situ hybridization we investigated amplification of chromosome band 1q21 (Amp1q21) in more than 500 untreated patients with monoclonal gammopathy of undetermined significance (MGUS; n = 14), smoldering multiple myeloma (SMM; n = 31), and newly diagnosed MM (n = 479) as well as 45 with relapsed MM. The frequency of Amp1q21 was 0% in MGUS, 45% in SMM, 43% in newly diagnosed MM, and 72% in relapsed MM (newly diagnosed versus relapsed MM, P < .001). Amp1q21 was detected in 10 of 12 patients whose disease evolved to active MM compared with 4 of 19 who remained with SMM (P < .001). Patients with newly diagnosed MM with Amp1q21 had inferior 5-year event-free/overall survival compared with those lacking Amp1q21 (38%/52% versus 62%/78%, both P < .001). Thalidomide improved 5-year EFS in patients lacking Amp1q21 but not in those with Amp1q21 (P = .004). Multivariate analysis including other major predictors revealed that Amp1q21 was an independent poor prognostic factor. Relapsed patients who had Amp1q21 at relapse had inferior 5-year postrelapse survival compared with those lacking Amp1q21 at relapse (15% versus 53%, P = .027). The proportion of cells with Amp1q21 and the copy number of 1q21 tended to increase at relapse compared with diagnosis. Our data suggest that Amp1q21 is associated with both disease progression and poor prognosis.

SSX cancer testis antigens are expressed in most multiple myeloma patients: co-expression of SSX1, 2, 4, and 5 correlates with adverse prognosis and high frequencies of SSX-positive PCs

Cancer testis antigens (CTAs) are tumor-specific antigens that may be useful targets for cancer vaccines. Here, CTA expression was examined in multiple myeloma (MM), a B-cell cancer characterized by malignant plasma cells (PCs) in the bone marrow (BM), and monoclonal gammopathy of undetermined significance (MGUS), a condition that can progress to MM. We screened a panel of patient BMs at different stages of malignancy for CTA expression by reverse transcription polymerase chain reaction RT-PCR. Here, SSX (synovial sarcoma, X chromosome) emerged as a promising candidate for an MM vaccine, having a profile similar to currently studied CTA, NY-ESO-1, and MAGE. SSX1, 2, 4, and 5 expression was studied further in 114 MM (total SSX, 61% of patients; SSX1, 42%; SSX2, 23%; SSX4, 38%; SSX5, 35%), 45 MGUS (total SSX, 24% of patients; SSX1, 9%; SSX4, 20%), and 12 control (0/12, 0%) subjects. Several expression patterns were observed, the most predominant being co-expression of SSX1, 2, 4, and 5 (called group A expression, in 20% of MM), which correlated with reduced survival (P=0.0006). Of the four genes, SSX2 had the strongest association with reduced survival (P=0.0001). SSX protein expression ranged from 13.5% of PCs in an SSX1/SSX4 co-expressor to as high as 88% of PCs in group A expressor, exceeding reported frequencies of NY-ESO-1 and MAGE in MM. In single PCs from group A patients, we detected variable degrees of SSX co-expression, emphasizing the heterogeneity of CTA expression within tumor cell populations. These results demonstrate that SSX is a frequently expressed CTA in MM and highlight its potential as an MM vaccine candidate.

Impaired class switch recombination (CSR) in Waldenstrom macroglobulinemia (WM) despite apparently normal CSR machinery

Analysis of clonotypic isotype class switching (CSR) in Waldenström macroglobulinemia (WM) and IgM monoclonal gammopathy of undetermined significance (MGUS) reveals a normal initial phase of B-cell activation as determined by constitutive and inducible expression of activation-induced cytidine deaminase (AID). Switch mu (Smu) analysis shows that large deletions are not common in WM or IgM MGUS. In CD40L/IL-4-stimulated WM cultures from 2 patients, we observed clonotypic IgG exhibiting intraclonal homogeneity associated with multiple hybrid Smu/Sgamma junctions. This suggests CSR had occurred within WM cells. Nevertheless, the estimated IgG/IgM-cell frequency was relatively low (1/1600 cells). Thus, for the majority of WM B cells, CSR does not occur even when stimulated in vitro, suggesting that the WM cell is constitutively unable to or being prevented from carrying out CSR. In contrast to WM, the majority of IgM MGUS clones exhibit intraclonal heterogeneity of IgH VDJ. Furthermore, most IgM MGUS accumulate more mutations in the upstream Smu region than do WM, making them unlikely WM progenitors. These observations suggest that switch sequence analysis may identify the subset of patients with IgM MGUS who are at risk of progression to WM.

Imaging techniques used in the diagnosis, staging, and follow-up of patients with myeloma

Radiologists play a central role in the diagnosis, initial staging, follow-up, and restaging of patients with myeloma. This review article attempts to familiarize the reader with all the various types of myeloma, their imaging appearances and useful imaging strategies. The staging system for myeloma patients has been updated and now includes findings from advanced imaging modalities. Radiologists have a vast array of imaging modalities at their disposal to aid them in diagnosis, staging, and follow-up. Currently, conventional radiographic skeletal surveys, magnetic resonance imaging, and F-18 FDG PET/CT examinations are the most useful instruments.

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.

IgM paraproteinaemic neuropathies

PURPOSE OF REVIEW

To conduct a critical review of recent studies on the pathogenesis and treatment of IgM paraproteinaemic neuropathies and analyse their implication for patient management.

RECENT FINDINGS

A better definition and classification of IgM monoclonal gammopathies has led to recommendations on therapeutic strategies for these patients, particularly for those with the asymptomatic form of Waldenström macroglobulinemia. Studies on the pathogenetic role of IgM paraprotein in neuropathy have led to the identification of a novel antibody reactivity against trisulfated heparin disaccharide, which was associated with painful, predominantly sensory, axonal distal neuropathy. Pathological studies on patients with axonal polyneuropathy and no antibody reactivity of the IgM paraprotein have shown that vasculitis may play an important role in this form of neuropathy, as possibly confirmed by its positive response to steroids. A number of open pilot trials have addressed the effect in IgM paraproteinaemic neuropathies of the humanized monoclonal antibody (rituximab) directed against the CD20 antigen. Even if the results of these studies are less promising than initially hoped, they provide evidence that rituximab may be effective in some patients with this neuropathy.

SUMMARY

New insights into the pathogenesis of axonal forms of IgM paraproteinaemic neuropathy have derived from the identification of novel antibody reactivity and of vasculitis. The latter finding may justify the use of steroids, otherwise ineffective in IgM paraproteinaemic neuropathy. Rituximab has opened the way to more selective and apparently safer immune therapies for this neuropathy, but its efficacy needs to be confirmed by randomized controlled trials.

Monoclonal immunoglobulin production is a frequent event in patients with mucosa-associated lymphoid tissue lymphoma

PURPOSE

Mucosa-associated lymphoid tissue (MALT) lymphoma comprises 7% of all newly diagnosed non-Hodgkin's lymphomas and is therefore among the most common lymphoma entities. Monoclonal gammopathy due to production of a monoclonal immunoglobulin by lymphoma cells is a well-known phenomenon associated with various types of B-cell non-Hodgkin's lymphomas. The objective of the present study was to evaluate the incidence and clinical relevance of paraprotein (PP) production in patients with MALT lymphoma.

EXPERIMENTAL DESIGN

Fifty two patients were prospectively evaluated with regard to differentiation of the MALT lymphoma cells, t(11;18) translocation, monoclonal immunoglobulin production, Helicobacter pylori (HP) status, stage, treatment, and clinical outcome.

RESULTS

Nineteen of 52 MALT lymphoma patients (36%) had PP (8 IgMkappa, 6 IgGkappa, 4 IgMlambda, and 1 IgAkappa). The histologic feature of plasmacytic differentiation correlated significantly with the production of PP (P = 0.001). No correlation was found between PP and clinical stage, HP status, and t(11;18) status. PP was, however, negatively associated with response to eradication of HP in gastric MALT lymphoma, and PP levels declined significantly in patients responding to chemotherapy or radiation. Importantly, both immunofixation and serum electrophoresis have to be performed to detect low PP levels.

CONCLUSIONS

In conclusion, PP levels may probably be used as a potential prognostic tool for response to HP eradication, and serial measurements may also allow for noninvasive assessment of response to radiation or chemotherapy in patients with MALT lymphoma.

Evolution of B-cell clonal expansions with age

B-cell clonal expansions (BCE) in young mice are transient, detectable for less than 4 weeks. In contrast, BCE in old mice persist more than 2 months. The greater persistence of BCE in old mice does not appear to be due to the age of the host as the survival of phenyloxazolone chicken serum albumin-induced BCE in most old mice was shorter than in young mice. This raises the possibility that persistent BCE seen in old mice develop over time from transient BCE present earlier in life. To test this hypothesis, young C57BL/6 mice were immunized with hen egg lysozyme (HEL) during the first year of life. By 28 months of age, the majority of these mice had developed a benign, persistent BCE associated with a HEL-specific serum mIg. We also investigated whether benign, persistent BCE, present in 18-month-old mice, can evolve into B-cell lymphomas. We observed that four of eight C57BL/6 mice that survived to 29 months of age had developed diffuse large cell lymphomas. In three of these mice, this diagnosis was made by microscopic analysis of the lymphoid organs. In one mouse, a macroscopic lymphoma was present that permitted us to demonstrate that the IgH mRNA CDR3 length and sequence in the malignant lymphoma was derived from a persistent BCE present 11 months earlier. Together these observations are consistent with the hypothesis that stepwise accumulation of genetic alterations combined with Darwinian selection underlies the evolution of B cells from transient BCE in young mice into persistent BCE, serum mIg, and B-cell lymphomas observed in older mice.

Waldenström's macroglobulinemia developing in a patient with multiple sclerosis: coincidence or association?

Multiple sclerosis (MS) has been reported in association with haematological abnormalities, including monoclonal gammopathies. We present a 54-year-old male patient with a 30-year history of MS who was admitted to our hospital for investigation of anaemia and increased erythrocyte sedimentation rate. A monoclonal IgM protein was detected by serum protein immunofixation, while bone marrow biopsy indicated a 70% infiltration by small lymphoplasmacytoid cells, in the context of a lymphoplasmacytoid immunocytoma, findings compatible to the diagnosis of Waldenström's macroglobulinemia (WM). To our knowledge, this is the first report of WM in a patient with MS. Further to the coexistence of the two diseases observed in the case presented here, there is additional evidence suggesting that the association of MS with plasma cell dyscrasias may not be coincidental.

Tissue inhibitor of metalloproteinase 1 (TIMP-1) promotes plasmablastic differentiation of a Burkitt lymphoma cell line: implications in the pathogenesis of plasmacytic/plasmablastic tumors

Tissue inhibitor of metalloproteinase 1 (TIMP-1) is a stromal factor with multiple functions. Overexpression of TIMP-1 correlates with aggressive clinical behavior of a spectrum of tumors. Here, for the first time, we address the role of TIMP-1 in the pathogenesis of B-cell lymphomas. An Epstein-Barr virus (EBV)-negative Burkitt lymphoma cell line with ectopic TIMP-1 expression (TIMP-1JD38) was used to identify genes induced/repressed by TIMP-1. Differentially expressed genes were analyzed by cDNA microarray, and they were validated by immunohistochemistry, flow cytometry, and Western blotting. Analysis revealed changes of genes coding for B-cell growth/differentiation, transcription, and cell cycle regulators. TIMP-1 repressed expression of germinal center (GC) markers CD10, Bcl-6, PAX-5 and up-regulated plasma cell-associated antigens CD138, MUM-1/IRF-4, XBP-1, and CD44, suggesting a plasma cell differentiation. This is accompanied by activation of signal transducer and activator of transcription 3 (STAT-3) and switch to cyclin D2 expression. However, TIMP-1JD38 cells expressed an inactive form of XBP-1, lacking antibody production/secretion. This incomplete plasmacytic differentiation occurs without altering cell proliferation, and despite c-Myc deregulation, indicating an arrested plasmacytic/plasmablastic stage of differentiation. Further validation in human lymphoma cell lines and in primary B-cell tumors demonstrated a predominant TIMP-1 expression in tumors with plasmacytic/plasmablastic phenotypes, including multiple myelomas. These findings strongly support TIMP-1 as an important factor in the pathogenesis of plasmacytic/plasmablastic tumors.