14q32 Translocations discriminate IgM multiple myeloma from Waldenstrom's macroglobulinemia

Precision medicine for multiple myeloma: The case for translocation (11;14)

The t(11;14) translocation is among the most prevalent cytogenetic abnormalities in multiple myeloma (MM), distinguished by its unique features and biology that have been thoroughly explored for decades. What further sets this MM subtype apart is its oscillating prognostic significance, from initially being considered a favorable alteration to intermediate risk and potential future reclassification as favorable risk. Despite not being inherently a high-risk alteration indicative of an aggressive phenotype, it appears that t(11;14)-MM is less responsive to novel agents like proteasome inhibitors and immunomodulatory drugs which have otherwise transformed the disease's treatment landscape, perhaps partially explained by its reduced propensity for immunoglobulin production and oligosecretory nature. However, its distinct reliance on Bcl-2 has heightened its sensitivity to venetoclax. Further subclassification based on morphological and genomic characteristics could enhance our prediction models of treatment responses and enable more tailored therapeutic strategies for patients. This review aims to encapsulate the existing research evidence in this area.

Management of lytic bone disease in lymphoplasmacytic lymphoma: A case report and review of the literature

Waldenström macroglobulinemia (WM)/lymphoplasmacytic lymphoma (LPL) is often differentiated from myeloma based on the presence of lytic bone lesions (LBL). However, WM/LPL can present with LBL, and management is poorly understood. We describe a case of an 81-year-old woman with LPL who presented with LBL and was successfully treated with chemoimmunotherapy.

Clinical Presentation and Gene Expression Profiling of Immunoglobulin M Multiple Myeloma Compared With Other Myeloma Subtypes and Waldenström Macroglobulinemia

PURPOSE

Multiple myeloma (MM) is a clonal bone marrow disease characterized by the neoplastic transformation of differentiated postgerminal B cells. It is a heterogeneous disease both at the genetic level and in terms of clinical outcome. Immunoglobulin M (IgM) MM is a rare subtype of myeloma. Similar to Waldenström macroglobulinemia (WM), patients with MM experience IgM monoclonal gammopathy; however, both diseases are distinct in terms of treatment and clinical behavior.

MATERIALS AND METHODS

To shed light on the presentation of IgM MM, its prognosis, and its gene expression profiling, we identified and characterized 21 patients with IgM MM from our database.

RESULTS

One of these patients presented with a rare IgM monoclonal gammopathy of undetermined significance that progressed to smoldering myeloma. The median survival of the 21 patients was 4.9 years, which was comparable to a matched group of patients with non-IgM MM with similar myeloma prognostic factors (age, gender, albumin, creatinine, anemia, lactate dehydrogenase, β₂-microglobulin, cytogenetics abnormalities), but much less than the median survival reported for patients with WM (9 years). We identified a cluster of genes that differ in their expression profile between MM and WM and found that the patients with IgM MM displayed a gene expression profile most similar to patients with non-IgM MM, confirming that IgM MM is a subtype of MM that should be differentiated from WM.

CONCLUSION

Because the prognosis of IgM MM and WM differ significantly, an accurate diagnosis is essential. Our gene expression model can assist with the differential diagnosis in controversial cases.

Comprehensive genomic profiling of IgM multiple myeloma identifies IRF4 as a prognostic marker

Immunoglobulin M multiple myeloma (IgM MM) is an extremely rare subtype of multiple myeloma with a poor clinical outcome. In this study, bone marrow aspirates of MM patients, including two cases of IgM MM, were analyzed by whole exome sequencing and RNA sequencing. Recurrent somatic mutations in the NRAS, KRAS, CCND1, DIS3, and TP53 genes were found in IgM MM and other types of MM, in agreement with previous studies. Overall transcription profiles of IgM and other types of MM clustered together, but separate from normal blood or peripheral plasma cells. Among the differentially expressed genes in IgM MM, IRF4 was highly expressed in IgM as well as in a subset of other types of MM patients. Thus, IRF4 is an independent prognostic factor for general MM patients. Taken together, the somatic mutation and transcriptome profiles support the idea that IgM MM can be classified as an aggressive MM subtype.

Current applications of multiparameter flow cytometry in plasma cell disorders

Multiparameter flow cytometry (MFC) has become standard in the management of patients with plasma cell (PC) dyscrasias, and could be considered mandatory in specific areas of routine clinical practice. It plays a significant role during the differential diagnostic work-up because of its fast and conclusive readout of PC clonality, and simultaneously provides prognostic information in most monoclonal gammopathies. Recent advances in the treatment and outcomes of multiple myeloma led to the implementation of new response criteria, including minimal residual disease (MRD) status as one of the most relevant clinical endpoints with the potential to act as surrogate for survival. Recent technical progress led to the development of next-generation flow (NGF) cytometry that represents a validated, highly sensitive, cost-effective and widely available technique for standardized MRD evaluation, which also could be used for the detection of circulating tumor cells. Here we review current applications of MFC and NGF in most PC disorders including the less frequent solitary plasmocytoma, light-chain amyloidosis or Waldenström macroglobulinemia.

Genomics, Signaling, and Treatment of Waldenström Macroglobulinemia

Next-generation sequencing has revealed recurring somatic mutations in Waldenström macroglobulinemia (WM). Commonly recurring mutations include MYD88 (95% to 97%), CXCR4 (30% to 40%), ARID1A (17%), and CD79B (8% to 15%). Diagnostic discrimination of WM from overlapping B-cell malignancies is aided by MYD88 mutation status. Transcription is affected by MYD88 and CXCR4 mutations and includes overexpression of genes involved in VDJ recombination, CXCR4 pathway signaling, and BCL2 family members. Among patients with MYD88 mutations, those with CXCR4 mutations show transcriptional silencing of tumor suppressors associated with acquisition of mutated MYD88. Deletions involving chromosome 6q are common and include genes that modulate nuclear factor-κB, BCL2, BTK, apoptosis, differentiation, and ARID1B. Non-chromosome 6q genes are also frequently deleted and include LYN, a regulator of B-cell receptor signaling. MYD88 and CXCR4 mutations affect WM disease presentation and treatment outcome. Patients with wild-type MYD88 show lower bone marrow disease burden and serum immunoglobulin M levels but show an increased risk of death. Patients with CXCR4 mutations have higher bone marrow disease burden, and those with nonsense CXCR4 mutations have higher serum immunoglobulin M levels and incidence of symptomatic hyperviscosity. Mutated MYD88 triggers BTK, IRAK1/IRAK4, and HCK growth and survival signaling, whereas CXCR4 mutations promote AKT and extracellular regulated kinase-1/2 signaling and drug resistance in the presence of its ligand CXCL12. Ibrutinib is active in patients with WM and is affected by MYD88 and CXCR4 mutation status. Patients with mutated MYD88 and wild-type CXCR4 mutation status exhibit best responses to ibrutinib. Lower response rates and delayed responses to ibrutinib are associated with mutated CXCR4 in patients with WM. MYD88 and CXCR4 mutation status may be helpful in treatment selection for symptomatic patients. Novel therapeutic approaches under investigation include therapeutics targeting MYD88, CXCR4, and BCL2 signaling.

Bone marrow macrophages in Waldenström's macroglobulinemia: a report of four cases

It is well known that some B-cell lymphomas are accompanied by a prominent epithelioid cell response, caused by activated macrophages, such as marginal zone B-cell lymphoma of a mucosa-associated lymphoid tissue. We investigated six bone marrow samples from four cases of Waldenström's macroglobulinemia and report a unique observation that large conjugates of tumor cells around a macrophage were prominent in all cases, particularly in one case, the bone marrow of which contained increased CD163-positive macrophages. Mast cells were increased in all the samples, some of which seemed to be in close contact with tumor cells. We consider that the conjugates represented close interactions of tumor cells, macrophages, and mast cells by cell-to-cell contact. Three of the present cases showed a favorable course. On the other hand, one case suffered from severe anemia and thrombocytopenia due to hemophagocytic syndrome at the second admission and showed a severe clinical course. Clinicians should be aware of the risk of lymphoma-associated hemophagocytic syndrome in this low-grade lymphoma, although many of the patients with hemophagocytic syndrome in Japan have aggressive lymphomas such as diffuse large B-cell lymphoma.

How I treat Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is a B-cell neoplasm manifested by the accumulation of clonal immunoglobulin (Ig)M-secreting lymphoplasmacytic cells. MYD88 and CXCR4 warts, hypogammaglobulinemia, infections, myelokathexis syndrome-like somatic mutations are present in >90% and 30% to 35% of WM patients, respectively, and impact disease presentation, treatment outcome, and overall survival. Familial predisposition is common in WM. Asymptomatic patients should be observed. Patients with disease-related hemoglobin <10 g/L, platelets <100 × 10(9)/L, bulky adenopathy and/or organomegaly, symptomatic hyperviscosity, peripheral neuropathy, amyloidosis, cryoglobulinemia, cold-agglutinin disease, or transformed disease should be considered for therapy. Plasmapheresis should be used for patients with symptomatic hyperviscosity and before rituximab for those with high serum IgM levels to preempt a symptomatic IgM flare. Treatment choice should take into account specific goals of therapy, necessity for rapid disease control, risk of treatment-related neuropathy, immunosuppression and secondary malignancies, and planning for future autologous stem cell transplantation. Frontline treatments include rituximab alone or rituximab combined with alkylators (bendamustine and cyclophosphamide), proteasome inhibitors (bortezomib and carfilzomib), nucleoside analogs (fludarabine and cladribine), and ibrutinib. In the salvage setting, an alternative frontline regimen, ibrutinib, everolimus, or stem cell transplantation can be considered. Investigational therapies under development for WM include agents that target MYD88, CXCR4, BCL2, and CD27/CD70 signaling, novel proteasome inhibitors, and chimeric antigen receptor-modified T-cell therapy.

Waldenström macroglobulinemia: from biology to treatment

Waldenström macroglobulinemia (WM) is distinct B-cell lymphoproliferative disorder primarily characterized by bone marrow infiltration of lymphoplasmacytic cells along with production of a serum monoclonal (IgM). In this review, we describe the biology of WM, the diagnostic evaluation for WM with a discussion of other conditions that are in the differential diagnosis and clinical manifestations of the disease as well as current treatment options. Within the novel agents discussed are everolimus, perifosine, enzastaurin, panobinostat, bortezomib and carfilzomib, pomalidomide and ibrutinib. Many of the novel agents have shown good responses and have a better toxicity profile compared to traditional chemotherapeutic agents, which makes them good candidates to be used as primary therapies for WM in the future.

IgM multiple myeloma: pathologic evaluation of a rare entity

OBJECTIVES

To delineate the pathology of immunoglobulin M-producing multiple myeloma (IgM MM).

METHODS

Clinicopathologic data were reviewed for 15 cases meeting World Health Organization criteria for MM and having a serum IgM paraprotein. Immunohistochemistry was performed on diagnostic bone marrow specimens for common B-cell and plasma cell markers.

RESULTS

Of the 15 IgM MM bone marrows reviewed, 6 (40%) had lymphoplasmacytoid cytology, and 12 (80%) expressed CD19, CD20, and/or CD45. Cyclin D1 expression was common (11 cases, 73%) and usually associated with t(11;14). No cases expressed CD5 or had an associated CD5-positive B-cell population. CD117 was positive in 20% of cases.

CONCLUSIONS

The frequent B-cell-associated antigen expression by IgM MM distinguishes it from other MM types, causing significant pathologic overlap with lymphoplasmacytic lymphoma (LPL). However, IgM MM is usually distinguished from LPL by aberrant cyclin D1 expression or t(11;14). Therefore, assessing for these abnormalities is recommended when evaluating bone marrow involvement by IgM-associated lymphoplasmacytoid disorders.

CD20-negative low-grade B cell lymphoma showing immunophenotypic and genotypic features resembling plasma cell myeloma

Here we demonstrate a unique case of CD20-negative low-grade B cell lymphoma showing immunophenotypic and genotypic features resembling multiple myeloma. The female patient had no abnormal masses, splenomegaly, swelled lymph nodes, or bone lesions. Although serum levels of IgG, IgA, and IgM were decreased without M protein, κ-type Bence-Jones protein was observed. In bone marrow, monotonous proliferation of small to medium-sized lymphoid cells was observed without classical myeloma cells, the same histological findings as lymphoplasmacytic lymphoma. The cells were CD38+, CD138+, CD43+, CD44+, CD3-, CD4-, CD5-, CD7-, CD8-, CD10-, CD11b-, CD19-, CD20-, CD21-, CD23-, CD24-, CD25-, CD27-, CD40-, CD45-, and CD56-. Surface or cytoplasmic IgM, κ, or λ were all negative. Chromosomal analysis demonstrated t(11;14)(q13;q32). The present case may belong to a new entity of low-grade B cell lymphoma with the same histological findings as lymphoplasmacytic lymphoma, mainly proliferated in bone marrow whose immunophenotype and genotype are similar to plasma cell myeloma.

How to manage Waldenstrom's macroglobulinemia

Waldenstrom's macroglobulinemia (WM) is very distinct from other indolent lymphoma subtypes: by definition it is accompanied by a monoclonal IgM gammopathy; it presents always with bone marrow infiltration and often with clinical symptoms such as neuropathy or hyperviscosity. These disease characteristics and the frequently advanced age of the WM patient pose a major challenge to the treating clinician even today. Recently, there has been not only substantial progress in our understanding of the biology of WM, but we have also significantly improved our tools to prognostify and to treat patients with this disease. This review summarizes our current knowledge about WM and aims at offering a guideline for the clinical management of patients with this lymphoma subtype, covering questions on how to manage diagnosis, prognostification and treatment based on the most recent data.

IgM multiple myeloma: disease definition, prognosis, and differentiation from Waldenstrom's macroglobulinemia

IgM multiple myeloma (MM) and Waldenstrom's macroglobulinemia (WM) are two distinct hematologic entities with the common finding of an IgM monoclonal gammopathy. Distinguishing these two diagnoses is critical as the approach to therapy is different. A priori, we defined IgM MM as a symptomatic clonal plasma cell proliferative disorder characterized by an IgM monoclonal protein (regardless of size), 10% or more plasma cells on bone marrow biopsy, plus the presence of lytic bone lesions and/or translocation t(11;14). Twenty-one patients met this definition of IgM MM. All 21 patients had lytic bone lesions. Of the 16 evaluated with FISH, 6 (38%) demonstrated t(11;14). Median overall survival was 30 months, which is similar to non-IgM myeloma patients treated during this period and shorter than what would be expected for WM. In this, the largest series of patients with IgM MM, we describe the clinical features and prognosis of patient with IgM MM using a strict definition for the disease. The subset of patients without lytic lesions or t(11;14) but with immunophenotypic features suggestive of MM need further study.

[Waldenström's macroglobulinemia]

Waldenström's macroglobulinemia (WM) is a B-cell disorder characterized primarily by bone marrow infiltration with lymphoplasmacytic cells, along with the presence of an IgM monoclonal gammopathy in the blood. WM remains incurable with a median of 8-year of overall survival for patients with symptomatic WM. Treatment is postponed for asymptomatic patients and progressive anemia is the most common indication for initiation of treatment. The main therapeutic options include alkylating agents, nucleoside analogues, and rituximab, either alone or in combination. Studies involving new combination chemotherapy are ongoing and preliminary results are encouraging. However, there are several limitations to these approaches. The complete response rate is low and the treatment free survival is short in many patients, no specific agent or regimen has been shown to be superior to another, and no treatment has been specifically approved for WM. As such, new therapeutic agents are needed for the treatment of WM. In ongoing efforts, we and others have sought to exploit advances made in the understanding of the biology of WM so as to better target therapeutics for this malignancy. These efforts have led to the development of proteasome inhibitors as bortezomib, several Akt/mTor inhibitors, such as perifosine and Rad001. Many other agents and monoclonal antibodies are currently being tested in clinical trials and seem promising. This article provides an update of the current preclinical studies and clinical efforts for the development of novel agents in the treatment of WM.

How I treat Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is a distinct B-cell disorder resulting from the accumulation, predominantly in the bone marrow, of clonally related IgM-secreting lymphoplasmacytic cells. Genetic factors play an important role, with 20% of patients demonstrating a familial predisposition. Asymptomatic patients should be observed. Patients with a disease-related hemoglobin level less than 10 g/L, platelet count less than 100 × 109/L, bulky adenopathy or organomegaly, symptomatic hyperviscosity, peripheral neuropathy, amyloidosis, cryoglobulinemia, cold-agglutinin disease, or evidence of disease transformation should be considered for therapy. Plasmapheresis should be considered for symptomatic hyperviscosity and for prophylaxis in patients in whom rituximab therapy is contemplated. The use of rituximab as monotherapy or in combination with cyclophosphamide, nucleoside analog, bortezomib, or thalidomide-based regimens can be considered for the first-line therapy of WM and should take into account specific treatment goals, future autologous stem cell transplantation eligibility, and long-term risks of secondary malignancies. In the salvage setting, the reuse or use of an alternative frontline regimen can be considered as well as bortezomib, alemtuzumab, and stem cell transplantation. Newer agents, such as bendamustine and everolimus, can also be considered in the treatment of WM.

Update on therapeutic options in Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is a B-cell disorder characterized primarily by bone marrow infiltration with lymphoplasmacytic cells (LPCs), along with demonstration of an IgM monoclonal gammopathy in the blood. WM remains incurable, with 5-6 yr median overall survival for patients with symptomatic WM. The main therapeutic options include alkylating agents, nucleoside analogues, and rituximab, either in monotherapy or in combination. Studies involving combination chemotherapy are ongoing, and preliminary results are encouraging. However, there are several limitations to these approaches. The complete response rate is low and the treatment free survival are short in many patients, no specific agent or regimen has been shown to be superior to another, and no treatment has been specifically approved for WM. As such, novel therapeutic agents are needed for the treatment of WM. In ongoing efforts, we and others have sought to exploit advances made in the understanding of the biology of WM so as to develop new targeted therapeutics for this malignancy. These efforts have led to the development of proteasome inhibitors, of them bortezomib, several Akt/mTor inhibitors, such as perifosine and Rad001, and immunomodulatory agents such as thalidomide and lenalidomide. Many agents and monoclonal antibodies are currently being tested in clinical trials and seem promising. This report provides an update of the current preclinical studies and clinical efforts for the development of novel agents in the treatment of WM.

Waldenstrom macroglobulinemia

In the past years, new developments have occurred both in the understanding of the biology of Waldenstrom Macroglobulinemia (WM) and in therapeutic options for WM. WM is a B-cell disorder characterized primarily by bone marrow infiltration with lymphoplasmacytic cells, along with demonstration of an IgM monoclonal gammopathy. Despite advances in therapy, WM remains incurable, with 5-6 years median overall survival of patients in symptomatic WM. Therapy is postponed for asymptomatic patients, and progressive anemia is the most common indication for initiation of treatment. The main therapeutic options include alkylating agents, nucleoside analogues, and rituximab. Studies involving combination chemotherapy are ongoing, and preliminary results are encouraging. No specific agent or regimen has been shown to be superior to another for treatment of WM. As such, novel therapeutic agents are needed for the treatment of WM. In ongoing efforts, we and others have sought to exploit advances made in the understanding of the biology of WM so as to better target therapeutics for this malignancy. These efforts have led to the development of several novel agents including the proteasome inhibitor bortezomib, and several Akt/mTor inhibitors, perifosine and Rad001, and immunomodulatory agents such as thalidomide and lenalidomide. Studies with monoclonal antibodies are ongoing and promising including the use of alemtuzumab, SGN-70, and the APRIL/BLYS blocking protein TACI-Ig atacicept. Other agents currently being tested in clinical trials include the PKC inhibitor enzastaurin, the natural product resveratrol, as well as the statin simvastatin. This report provides an update of the current preclinical studies and clinical efforts for the development of novel agents in the treatment of WM.

Establishment of BCWM.1 cell line for Waldenström's macroglobulinemia with productive in vivo engraftment in SCID-hu mice

A significant impairment in understanding the biology and advancing therapeutics for Waldenstrom's macroglobulinemia (WM) has been the lack of a representative cell line and animal model. We, therefore, report on the establishment of the BCWM.1 cell line, which was derived from the long-term culture of CD19(+) selected bone marrow lymphoplasmacytic cells isolated from an untreated patient with WM. BCWM.1 cells morphologically resemble lymphoplasmacytic cells (LPC) and propagate in RPMI-1640 medium supplemented with 10% fetal bovine serum. Phenotypic characterization by flow cytometric analysis demonstrated typical WM LPC characteristics: CD5(-), CD10(-), CD19(+), CD20(+), CD23(+), CD27(-), CD38(+), CD138(+), CD40(+), CD52(+), CD70(+), CD117(+), cIgM(+), cIgG(-), cIgA(-), ckappa(-), clambda(+), as well as the survival proteins APRIL and BLYS, and their receptors TACI, BCMA and BAFF-R. Enzyme-linked immunosorbent assay studies demonstrated secretion of IgMlambda and soluble CD27. Karyotypic and multicolor fluorescence in situ hybridization studies did not demonstrate cytogenetic abnormalities. Molecular analysis of BCWM.1 cells confirmed clonality by determination of IgH rearrangements. Inoculation of BCWM.1 cells in human bone marrow chips implanted in severe combined immunodeficient-hu mice led to rapid engraftment of tumor cells and serum detection of human IgM, lambda, and soluble CD27. These studies support the use of BCWM.1 cells as an appropriate model for the study of WM, which in conjunction with the severe combined immunodeficient-hu mouse model may be used as a convenient model for studies focused on both WM pathogenesis and development of targeted therapies for WM.

Nephrotic syndrome in a patient with IgM myeloma with associated neutrophilia

An unusual case having IgM monoclonal gammopathy with clinical and pathologic features of multiple myeloma (MM) in association with neutrophilia and nephrotic syndrome is reported. The patient showed lytic bone lesions, decreased IgG and IgA levels, Bence-Jones proteinuria, nephrotic proteinuria with edema, and histological plasma cell infiltration typical of MM. Moreover, mature neutrophilic leukocytosis, hepatomegaly, high leukocyte alkaline phosphatase score (LAP), absence of Philadelphia (Ph) chromosome and bcr gene rearrangement were also evidenced, all these features representing findings typical of the recently described plasma cell dyscrasia-associated neutrophilia. After the diagnosis, the patient was treated with melphalan and prednisone, with an excellent response to the treatment. Different from the 30 cases so far reported, this is the first case of plasma-cell dyscrasia with associated neutrophilia due to IgM-producing monoclonal gammopathy. At the same time, this is the first reported case of nephrotic syndrome secondary to IgM myeloma.

Waldenström macroglobulinemia

In the past 36 months, new developments have occurred both in the understanding of the biology of Waldenström macroglobulinemia (WM) and in therapeutic options for WM. Here, we review the classification, clinical features, and diagnostic criteria of the disease. WM is a B-cell neoplasm characterized by lymphoplasmacytic infiltration of the bone marrow and a monoclonal immunoglobulin M (IgM) protein. The symptoms of WM are attributable to the extent of tumor infiltration and to elevated IgM levels. The most common symptom is fatigue attributable to anemia. The prognostic factors predictive of survival include the patient's age, β2-microglobulin level, monoclonal protein level, hemoglobin concentration, and platelet count. Therapy is postponed for asymptomatic patients, and progressive anemia is the most common indication for initiation of treatment. The main therapeutic options include alkylating agents, nucleoside analogues, and rituximab. Studies involving combination chemotherapy are ongoing, and preliminary results are encouraging. No specific agent or regimen has been shown to be superior to another for treatment of WM. Novel agents such as bortezomib, perifosine, atacicept, oblimersen sodium, and tositumomab show promise as rational targeted therapy for WM.

Gene expression profiling of B lymphocytes and plasma cells from Waldenström's macroglobulinemia: comparison with expression patterns of the same cell counterparts from chronic lymphocytic leukemia, multiple myeloma and normal individuals

The tumoral clone of Waldenström's macroglobulinemia (WM) shows a wide morphological heterogeneity, which ranges from B lymphocytes (BL) to plasma cells (PC). By means of genome-wide expression profiling we have been able to identify genes exclusively deregulated in BL and PC from WM, but with a similar expression pattern in their corresponding cell counterparts from chronic lymphocytic leukemia (CLL) and multiple myeloma (MM), as well as normal individuals. The differentially expressed genes have important functions in B-cell differentiation and oncogenesis. Thus, two of the genes downregulated in WM-BL were IL4R, which plays a relevant role in CLL B-cell survival, and BACH2, which participates in the development of class-switched PC. Interestingly, one of the upregulated genes in WM-BL was IL6. A set of four genes was able to discriminate clonal BL from WM and CLL: LEF1 (WNT/beta-catenin pathway), MARCKS, ATXN1 and FMOD. We also found deregulation of genes involved in plasma cell differentiation such as PAX5, which was overexpressed in WM-PC, and IRF4 and BLIMP1, which were underexpressed. In addition, three of the target genes activated by PAX5 - CD79, BLNK and SYK - were upregulated in WM-PC. In summary, these results indicate that both PC and BL from WM are genetically different from the MM and CLL cell counterpart.

Immunoglobulin Heavy Chain Sequence Analysis in Waldenström's Macroglobulinemia and Immunoglobulin M Monoclonal Gammopathy of Undetermined Significance

In this study, we used IGH sequence analysis to assess the maturational status of Waldenstrom's (WM) macroglobulinemia and its putative precursor immunoglobulin (Ig)-M monoclonal gammopathy of undetermined significance (MGUS). IGH sequence analysis was performed using standard methods in 23 cases (20 WM and 3 IgM MGUS as defined by consensus panel criteria). Waldenstrom's macroglobulinemia cases were characterized by heavily mutated IGH genes (median, 6.3%; range, 3.8%-13.9%) but without intraclonal variation (ICV). IgM MGUS was similarly characterized by somatic hypermutation (median, 7.5%; range, 7%-7.7%), but ICV was evident in 1 of the 3 cases. We would therefore conclude that WM is characterized by somatic hypermutation without ICV, which supports a derivation from postgerminal center/memory B cells. IgM MGUS is also characterized by somatic hypermutation but, in a manner similar to IgA/IgG MGUS, can be associated with ICV, although the significance of this remains unclear.

Waldenström's macroglobulinemia

The diagnosis of Waldenström's macroglobulinemia (WM) requires evidence of bone-marrow infiltration by lymphoplasmacytoid lymphoma and detection of serum monoclonal protein of IgM type. The normal counterpart of the WM malignant cell is believed to be a postgerminal-center B cell. The clinical manifestations and laboratory abnormalities associated with WM are related to direct tumor infiltration and to the amount and specific properties of IgM. Asymptomatic patients should be followed without treatment. When treatment is indicated, the three main choices for systemic frontline treatment are chlorambucil, the nucleoside analogues fludarabine or cladribine and the monoclonal antibody rituximab. There is evidence that high-dose therapy with autologous stem-cell transplantation is effective even in patients with advanced and resistant disease. Patient's age, hemoglobin and serum beta2-microglobulin before treatment are important prognostic variables which correlate with survival.

Rarity of IgH translocations in Waldenström macroglobulinemia

Comparatively little is known of the cytogenetics of Waldenström macroglobulinemia (WM). This is primarily due to the low proliferation of the clonal B cells, which precludes conventional karyotyping in many cases. Translocations involving the immunoglobulin heavy chain (IGH) gene at 14q32 are characteristic of many B-cell lymphomas and myelomas. Initial reports suggested that the t(9;14) was characteristic of lymphoplasmacytic lymphoma (the underlying pathological diagnosis in WM), but subsequent studies have failed to confirm the uniqueness of the translocation. To clarify this, we examined 69 cases of WM with interphase fluorescence in situ hybridization and failed to demonstrate an IgH translocation in 67 (97%). We conclude that IGH translocations are not a feature of WM, and the implications of this finding are discussed.

Lymphoplasmacytic lymphoma/waldenstrom macroglobulinemia: an evolving concept

The concept of Waldenstrom macroglobulinemia has evolved from the original description of a clinical syndrome to its more recent designation as a distinct clinicopathologic entity, that is, lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia (LPL/WM), in the World Health Organization (WHO) classification and by the participants of consensus meetings on WM. The diagnosis of LPL/WM, however, remains a challenge in daily practice. Distinguishing LPL/WM from other B-cell lymphomas, especially marginal zone B-cell lymphomas, which share overlapping morphologic features, is difficult. The traditional practice of separating LPL/WM from other lymphomas by an arbitrary level of serum IgM is no longer considered valid. The characteristic immunophenotype described for LPL/WM by the WHO classification, that is, CD5(-)CD10(-)CD23-, is observed in 60-80% of neoplasms, but variations from this pattern of antigen expression are common, with CD23 being detected in up to 40% of cases. Lack of a distinct molecular genetic hallmark complicates the distinction of LPL/WM from other B-cell lymphomas. Although the t(9;14) is stated to be present in 50% of cases in the WHO classification, translocations involving the Ig heavy chain including the t(9;14) are actually rare in LPL/WM. Deletion of 6q21-q23, a nonspecific finding, is the most common aberration reported in 40-70% of patients. At the molecular level, the neoplastic clone in most cases has undergone Ig variable gene mutation, but not isotype switching, and the clone retains the capability of plasmacytic differentiation. Currently, the diagnosis of LPL/WM can only be established by incorporating clinical and pathologic findings and excluding alternative diagnoses. In some cases, in our opinion, distinguishing LPL/WM from marginal zone B-cell lymphomas seems arbitrary using currently recommended criteria.

Clinicopathologic Features of Waldenström's Macroglobulinemia and Marginal Zone Lymphoma: Are They Distinct or the Same Entity?

Waldenstrom's macroglobulinemia (WM) is considered in the World Health Organization classification as a clinical syndrome associated with monoclonal immunoglobulin (Ig) M secretion, mainly observed in patients with lymphoplasmacytic lymphoma (LPL) and occasionally with other small B-cell lymphomas. Some authors consider it a rare distinct lymphoproliferative disorder with primary bone marrow infiltration and IgM monoclonal gammopathy. As LPL shares important morphologic and immunophenotypic overlaps with marginal zone B-cell lymphomas (MZLs) in cases showing plasmacytic maturation, it remains unclear if they constitute unique or distinct entities. Both diseases are composed of lymphocytes, lymphoplasmacytoid cells, and tumoral plasma cells with a surface (s) IgM-positive sIgD+/ cytoplasmic IgMpositive CD19+ CD20+ CD27+/ CD5 CD10 CD23 phenotype, without a specific marker. Extranodal mucosa-associated lymphoid tissue (MALT) lymphoma, nodal MZL (NMZL), and splenic MZL (SMZL) are distinct entities displaying common morphologic, immunophenotypic, and genetic characteristics. MALT lymphoma is clearly distinct from LPL, although bone marrow infiltration and IgM paraprotein are not rare. Splenic MZL and NMZL are incompletely characterized, but a plasmacytoid/plasmacytic differentiation, autoimmune manifestations, and monoclonal component are frequent in both diseases. Bone marrow involvement is constant in SMZL and present in 60% of NMZLs. Molecular IgVH gene analysis has confirmed this heterogeneity, particularly within SMZL, with mutated and unmutated cases. Further studies are needed to clarify the pathogenesis of these MZLs and their relationship with LPL.

Immunoglobulin M Myeloma: Evaluation of Molecular Features and Cytokine Expression

Immunoglobulin (Ig) M myeloma is a distinct entity with features of multiple myeloma (MM) and Waldenstrom's macroglobulinemia (WM). The malignant cells in IgM myeloma have a distinctive chromosomal translocation that differentiates them from WM. These cells are postgerminal-center in origin with isotype-switch transcripts. They appear to be arrested at a point of maturation between that of WM and MM. Preliminary data indicate that a pattern of osteoclast-activating factor and osteoprotegerin expression similar to that observed in classic MM is present in IgM myeloma. Additional studies on patients with this rare tumor may provide further insight into the pathogenesis of bone disease in plasma cell dyscrasias.

Amyloidosis and Waldenström’s Macroglobulinemia

Primary systemic amyloidosis is an immunoglobulin light chain disorder that is 1/5th as common as multiple myeloma. Amyloidosis is regularly seen in the practice of a hematologist and has recently undergone major advances in terms of the ability to evaluate responses as well as new therapeutic options that were not available when this topic was covered as an education session at the American Society of Hematology meeting 5 years ago. Waldenström macroglobulinemia (WM) is rarer than amyloidosis (1500 per year WM versus 3000 per year amyloid in the US), and recent consensus panels have established the definition of the disease, the diagnostic criteria, criteria for initiation of therapy and a new classification scheme. In this session, new developments in amyloid and macroglobulinemia, from suspicion of the diagnosis to treatment, are covered.

In Section I, Dr. Morie Gertz answers four specific questions: (1) When should amyloidosis be suspected? (2) How does one heighten ones index of suspicion for amyloid? (3) How is the diagnosis confirmed and the type classified as primary? (4) What is the prognosis and how is it accurately assessed? Recent findings on cardiac biomarkers, presenting features and use of the free light chain assay are reviewed. Staging for amyloid and recently proposed criteria of response and progression are covered.

In Section II, Dr. Giampaolo Merlini comprehensively reviews therapy of amyloidosis from the use of standard melphalan/prednisone to the recently described standard dose therapies including dexamethasone, thalidomide/dexamethasone, melphalan/dexamethasone and IV melphalan/dexamethasone. An extensive discussion of the role of high-dose therapy with stem cell reconstitution follows and includes patient selection, predictors of immediate morbidity and mortality, and survival expectation. Finally, a therapeuitc strategy is proposed.

In Section III, Drs. Steven Treon and Giampaolo Merlini review the most current information on WM. The consensus panel results and recommendations of the clinical pathologic definition of WM, the prognostic markers and the indications to initiate therapy in WM, the uniform response criteria in WM and available treatments for the disease are reviewed. Drs. Treon and Merlini cover recently published treatment protocols that use rituximab, purine nucleoside analogs, and alkylating agents. The current data on thalidomide, alpha interferon, and high-dose therapy are also covered.

Clinicopathological definition of Waldenstrom's macroglobulinemia: consensus panel recommendations from the Second International Workshop on Waldenstrom's Macroglobulinemia

This presentation represents consensus recommendations for the clinicopathological definition of Waldenstrom's macroglobulinemia (WM), which were prepared in conjunction with the Second International Workshop held in Athens, Greece during September 2002. WM is an uncommon lymphoproliferative disorder characterized primarily by bone marrow infiltration and IgM monoclonal gammopathy. It should be considered a distinct clinicopathological entity rather than a clinical syndrome secondary to IgM secretion. The underlying pathological diagnosis in WM is lymphoplasmacytic lymphoma as defined by the World Health Organization (WHO) and Revised European-American Lymphoma (REAL) classification criteria. The concentration of monoclonal IgM can vary widely in WM and it is not possible to define a concentration that reliably distinguishes WM from monoclonal gammopathy of undetermined significance (MGUS) and other lymphoproliferative disorders. A diagnosis of WM can therefore be made irrespective of IgM concentration if there is evidence on a bone marrow trephine biopsy of bone marrow infiltration by lymphoplasmacytic lymphoma with predominantly an intertrabecular pattern, supported by appropriate immunophenotypic studies. Simple criteria to distinguish patients with symptomatic WM who require therapy from those with asymptomatic WM and MGUS were also proposed. Patients with clinical features attributable to IgM monoclonal gammopathy but no overt evidence of lymphoma are considered to constitute a distinct clinical group and the term "IgM-related disorders" is proposed.

Origins of the malignant clone in typical Waldenstrom's macroglobulinemia

Histopathology and phenotypic considerations in IgM-secreting B-cell tumors allow distinction between different diseases, but insight into pathogenesis is restricted. Here, variable region (V) gene analysis can complement classification but, more importantly, can also reveal disease origins and clonal history. We used V(H) gene analysis to probe origins in Waldenstrom's macroglobulinemia (WM), and contrasted these with the less malignant counterpart, IgM-secreting monoclonal gammopathy of undetermined significance (MGUS). Limited data on WM sequences had previously shown evidence for somatic mutation, but with conflicting analysis of intraclonal variation in tumor sequences. To further the investigation, we analyzed seven cases of WM and compared these with three cases of IgM MGUS. In both diseases, V(H) genes were somatically mutated with no evidence of intraclonal variation, even at the MGUS stage. A sensitive V(H) gene-probe assay revealed no evidence for isotype switch transcripts in any of the WM and IgM MGUS cases. These findings reveal an origin of WM and IgM MGUS from a IgM cell, which transforms after cessation of somatic mutation but without initiating switch events. In contrast, IgM-secreting multiple myeloma arises at a later stage in differentiation, when isotype switch mechanisms have been engaged.