CD5, CD10, and CD23 expression in Waldenstrom's macroglobulinemia

Leukemic Involvement Is a Common Feature in Waldenström Macroglobulinemia at Diagnosis

Waldenström Macroglobulinemia (WM) is a lymphoplasmacytic lymphoma with bone marrow (BM) involvement and IgM monoclonal gammopathy. To date, no studies have focused specifically on peripheral blood (PB) involvement. In this study, 100 patients diagnosed with WM according to the World Health Organization (WHO) criteria were included based on the demonstration of MYD88mut in BM and the availability of PB multiparametric flow cytometry (MFC) analysis. Leukemic involvement by MFC was detected in 50/100 patients. A low percentage of mature small lymphocytes in PB smears was observed in only 15 cases. MYD88mut by AS-qPCR was detected in PB in 65/100 cases. In cases with leukemic expression by MFC, MYD88mut was detected in all cases, and IGH was rearranged in 44/49 cases. In 21/50 patients without PB involvement by MFC, molecular data were consistent with circulating disease (MYD88mut by AS-qPCR 3/50, IGH rearranged 6/50, both 12/50). Therefore, PB involvement by standard techniques was detected in 71/100 patients. MYD88mut was detected in PB by dPCR in 9/29 triple negative cases. Overall, 80% of the patients presented PB involvement by any technique. Our findings support the role of PB MFC in the evaluation of patients with IgM monoclonal gammopathy and provide reliable information on correlation with molecular features. The development of a feasible MFC assay may stand as an objective tool in the classification of mature B cell neoplasms presenting with IgM monoclonal gammopathy.

Mu heavy chain disease with MYD88 L265P mutation: an unusual manifestation of lymphoplasmacytic lymphoma

Background

Mu heavy chain disease is a rare lymphoid neoplasm characterized by vacuolated bone marrow plasma cells and secretion of defective mu immunoglobulin heavy chains. The biological basis of mu heavy chain disease is poorly understood.

Case presentation

We report a case of mu heavy chain disease with MYD88 L265P mutation and deletion of 6q, genetic aberrations that are both strongly associated with lymphoplasmacytic lymphoma/Waldenström macroglobulinemia. Identification of the truncated mu immunoglobulin was facilitated by mass spectrometric analysis of the patient’s serum.

Conclusions

Mu heavy chain disease has been described as similar to chronic lymphocytic leukemia; however, the frequency of lymphocytosis in mu heavy chain disease has not been previously reported. We reviewed all previously published mu heavy chain disease reports and found that lymphocytosis is uncommon in the entity. This finding, along with the emerging genetic feature of recurrent MYD88 mutation in mu heavy chain disease, argues that at least a significant subset of cases are more similar to lymphoplasmacytic lymphoma than to chronic lymphocytic leukemia.

Current approach to Waldenström Macroglobulinemia

Waldenström Macroglobulinemia (WM) is a unique, low grade, IgM lymphoplasmacytic lymphoma with a heterogeneous clinical course. A paucity of high-grade evidence from large phase 3 trials remains a major issue in the field despite a rapidly expanding therapeutic armamentarium against WM. Prior knowledge of the patients' MYD88^L265P and CXCR4 mutation status aids in treatment decision making if Bruton's tyrosine kinase (BTK) inhibitor therapy is being considered. Head-to head comparative data to inform optimal approach are lacking, and a particularly vexing issue for the clinicians is choosing between fixed-duration bendamustine-rituximab (BR) therapy and an indefinite BTK inhibitor-based regimen, given that both approaches are well tolerated and effective, particularly for the patient population harboring MYD88^L265P mutation. For the patients with MYD88^WT genotype, chemo-immunotherapy such as BR is preferred, although zanubrutinib, a potent second generation BTK inhibitor, with its reduced off target effects and greater BTK occupancy compared to its predecessor, ibrutinib, has also recently shown activity in MYD88^WT WM. This review summarizes the current literature pertaining to the diagnosis, prognosis, and the treatment of WM.

Flow cytometry in the diagnosis of mature B-cell lymphoproliferative disorders

B-lineage lymphoproliferative disorders (LPD) are rather frequent diseases, associated with specific clinical or biological features but also sometimes of fortuitous discovery. Multiparameter flow cytometry plays a major role for a rapid diagnostic indication, on peripheral blood or bone marrow samples in most instances, guiding complementary analyses and allowing for the proper therapeutic management of patients. After describing the important pre-analytical precautions required for an adequate assessment, the immunophenotypic features of small-cell and large-cell lymphomas are described in this review. The ubiquitous expression of CD19 is a first mandatory gating step. A possible clonal proliferation is then suspected by the demonstration of surface immunoglobulin light chain restriction. The aberrant presence of CD5 allows to segregate chronic lymphocytic leukemia and mantle cell lymphoma in most cases. Other LPD exhibit specific immunophenotypic features. A table of useful markers and a decision tree are provided. Of note, immunophenotypic data should as much as possible be interpreted in an integrated manner, involving the patient's clinical and other biological features, and be completed by further chromosomal and/or molecular investigations.

Gene Expression Profiling Reveals Aberrant T-cell Marker Expression on Tumor Cells of Waldenström's Macroglobulinemia

PURPOSE

That the malignant clone of Waldenström's macroglobulinemia (WM) demonstrates significant intraclonal heterogeneity with respect to plasmacytoid differentiation indicates the mechanistic complexity of tumorigenesis and progression. Identification of WM genes by comparing different stages of B cells may provide novel druggable targets.

EXPERIMENTAL DESIGN

The gene expression signatures of CD19⁺ B cells (BC) and CD138⁺ plasma cells (PC) from 19 patients with WM were compared with those of BCs from peripheral blood and tonsil and to those of PCs from the marrow of healthy (N-PC) and multiple myeloma donors (MM-PC), as well as tonsil (T-PC). Flow cytometry and immunofluorescence were used to examine T-cell marker expression on WM tumor cells.

RESULTS

Consistent with defective differentiation, both BCs and PCs from WM cases expressed abnormal differentiation markers. Sets of 55 and 46 genes were differentially expressed in WM-BC and WM-PC, respectively; and 40 genes uniquely dysregulated in WM samples were identified. Dysregulated genes included cytokines, growth factor receptors, and oncogenes not previously implicated in WM or other plasma cell dyscrasias. Interestingly, strong upregulation of both IL6 and IL6R was confirmed. Supervised cluster analysis of PC revealed that marrow-derived WM-PC was either MM-PC-like or T-PC-like, but not N-PC-like. The aberrant expression of T-cell markers was confirmed at the protein level in WM-BC.

CONCLUSIONS

We showed that comparative microarray profiles allowed gaining more comprehensive insights into the biology of WM. The data presented here have implications for the development of novel therapies, such as targeting aberrant T-cell markers in WM.

A Case of Bing-Neel Syndrome Successfully Treated with Ibrutinib

Bing–Neel syndrome is a rare manifestation of Waldenström macroglobulinemia characterized by lymphoplasmacytic cells' infiltration into the central nervous system. We present a case of a 74-year-old patient with a known diagnosis of Waldenström macroglobulinemia and newly depressed consciousness. Flow cytology of his cerebral spinal fluid demonstrated a lambda light chain-restricted population of B-cells consistent with a CD5+ CD10+ B-cell lymphoma. Magnetic resonance imaging suggested involvement of the left optic nerve sheath and the bilateral orbital and parietal parenchyma and leptomeninges. He was diagnosed with Bing–Neel syndrome and treated with intrathecal liposomal cytarabine, intravenous high-dose methotrexate, and rituximab without improvement. Subsequently, he started treatment with ibrutinib 560 mg daily and concurrent rituximab. Within three months, he showed clinical and radiologic improvement. The patient has continued on ibrutinib and has now been stable for over 36 months. This represents the longest reported period of successful treatment of Bing–Neel syndrome with ibrutinib.

CD13 expression in B cell malignancies is a hallmark of plasmacytic differentiation

The diagnosis of Waldenström Macroglobulinaemia (WM)/lymphoplasmacytic lymphoma (LPL) remains one of exclusion because other B-cell lymphoproliferative disorders (B-LPD), such as marginal zone lymphoma (MZL), can fulfil similar criteria, including MYD88 L265P mutation. It has been suggested that expression of the myeloid marker CD13 (also termed ANPEP) is more frequent in LPL than in other B-LPD and has also been described on normal and malignant plasma cells. Here, CD13 expression was tested in a cohort of 1037 B-LPD patients from 3 centres by flow cytometry. The percentage of CD13-expressing cells was found to be variable among B-LPD but significantly higher in WM/LPL (median 31% vs. 0% in non-WM/LPL, P < 0·001). In multivariate linear regression, CD13 expression remained significantly associated with a diagnosis of WM/LPL (P < 0·001). A cut-off value of 2% of CD19⁺ cells co-expressing CD13 yielded the best diagnostic performance for WM/LPL assertion. This was further improved by association with the presence or absence of IgM paraprotein. Finally, given that previously published transcriptomic data revealed no difference in CD13 (also termed ANPEP) mRNA between normal and pathological B-cells, the hypothesis of some post-transcriptional regulation must be favoured. These results suggest that testing for CD13 expression in routine flow cytometry panels could help to discriminate WM/LPL from other B-LPD.

Waldenstrom's Macroglobulinemia: An Update

Waldenstrom Macroglobulinemia is a rare lymphoproliferative disorder with distinctive clinical features. Diagnostic and prognostic characterisation in WM significantly changed with the discovery of two molecular markers: MYD88 and CXCR4. Mutational status of these latter influences both clinical presentation and prognosis and demonstrated therapeutic implications. Treatment choice in Waldenstrom disease is strictly guided by patients age and characteristics, specific goals of therapy, the necessity for rapid disease control, the risk of treatment-related neuropathy, disease features, the risk of immunosuppression or secondary malignancies and potential for future autologous stem cell transplantation. The therapeutic landscape has expanded during the last years and the approval of ibrutinib, the first drug approved for Waldenstrom Macroglobulinemia, represents a significant step forward for a better management of the disease.

Waldenstrom's Macroglobulinemia: An Update

Waldenstrom Macroglobulinemia is a rare lymphoproliferative disorder with distinctive clinical features. Diagnostic and prognostic characterisation in WM significantly changed with the discovery of two molecular markers: MYD88 and CXCR4. Mutational status of these latter influences both clinical presentation and prognosis and demonstrated therapeutic implications. Treatment choice in Waldenstrom disease is strictly guided by patients age and characteristics, specific goals of therapy, the necessity for rapid disease control, the risk of treatment-related neuropathy, disease features, the risk of immunosuppression or secondary malignancies and potential for future autologous stem cell transplantation. The therapeutic landscape has expanded during the last years and the approval of ibrutinib, the first drug approved for Waldenstrom Macroglobulinemia, represents a significant step forward for a better management of the disease.

Waldenström's macroglobulinemia: Two malignant clones in a monoclonal disease? Molecular background and clinical reflection

Waldenström's macroglobulinemia (WM) is a complex disease characterized by apparent morphological heterogeneity within the malignant clonal cells representing a continuum of small lymphocytes, plasmacytoid lymphocytes, and plasma cells. At the molecular level, the neoplastic B cell-derived clone has undergone somatic hypermutation, but not isotype switching, and retains the capability of plasmacytic differentiation. Although by classical definition, WM is formed by monoclonal expansion, long-lived clonal B lymphocytes are of heterogeneous origin. Even more, according to current opinion, plasma cells also conform certain population with pathogenic and clinical significance. In this article, we review the recent advances in the WM clonal architecture, briefly describe B-cell development during which the molecular changes lead to the malignant transformation and mainly focus on differences between two principal B-lineage clones, including analysis of their genome and transcriptome profiles, as well as immunophenotype features. We assume that the correct identification of a number of specific immunophenotypic molecular and expression alterations leading to proper aberrant clone detection can help to guide patient monitoring throughout treatment and successfully implement therapy strategies directed against both B- and plasma cell tumor WM clones.

Diagnostic Algorithm of Common Mature B-Cell Lymphomas by Immunohistochemistry

CONTEXT

- Different types of mature B-cell lymphomas, including plasma cell neoplasms, exhibit distinct immunohistochemical profiles, which enable them to be correctly diagnosed. However, except for rare examples of lymphoma-specific immunohistochemistry, such as cyclin D1 in mantle cell lymphoma and annexin A1 in hairy cell leukemia, immunohistochemical profiles of mature B-cell lymphomas overlap and lack specificity.

OBJECTIVES

- To systemically review immunohistochemical features associated with commonly encountered mature B-cell lymphomas based on the presence or absence of CD5 and CD10; to review the immunophenotypic profile of plasma cells derived from plasma cell myelomas and B-cell lymphomas; and to review a group of rare, aggressive B-cell lymphomas with antigen expression features of plasma cells.

DATA SOURCES

- Published and PubMed-indexed English literature was reviewed.

CONCLUSIONS

- Although the presence or absence of CD5 and CD10 expression should be included in the initial immunohistochemistry screening panel for mature B-cell lymphomas, appropriate and judicial use of other B-cell antigens is necessary to ensure correct diagnoses. Furthermore, although the status of CD5 and CD10 expression is associated with certain prototypes of B-cell lymphomas, their expression is not specific. Plasma cells from plasma cell neoplasias and B-cell lymphomas exhibit overlapping but relatively distinct immunophenotypes; thus, a panel of immunohistochemical markers (CD19, CD45, CD56, and CD117) can be employed for their proper identification. Lastly, CD138 staining results are almost always positive in a group of aggressive B-cell lymphomas with plasmablastic features, including plasmablastic plasma cell myeloma, plasmablastic lymphoma, and ALK-1⁺ large B-cell lymphoma.

Origin of Waldenstrom's macroglobulinaemia

Waldenstrom's macroglobulinaemia (WM) is an MYD88^L265P-mutated lymphoplasmacytic lymphoma that invades bone marrow and secretes monoclonal immunoglobulin M (IgM). WM cells are usually unable to undergo class switch recombination, and have mutated IGHV, with a typical immunophenotype CD19⁺/CD22^low+/CD23^-/CD25⁺/CD27⁺/CD45⁺/CD38^low+/SmIgM⁺ (negative for CD5, CD10, CD11c, CD103). This immunophenotype matches memory B cells (smIgM^-/+/CD10^-/CD19⁺/CD20⁺/CD27⁺/CD38^low+/CD45⁺), representing 30% of B cells in the blood. Fifty percent of them have not undergone class switch recombination and are IgM⁺. These cells have suffered somatic hypermutation as WM cells. Genetic abnormalities do not abrogate the capacity to progress to plasma cells that usually belong to the clonal WM compartment, with a normal immunophenotype and functional characteristics. However, some WM cells are CD27^-, MYD88^WT, without somatic hypermutation, or with class switch recombination capable of reactivation. Thus, most data support a B-memory-cell origin for WM, but a small fraction of cases may have a different origin.

[Clinical and biological characteristics of non-IgM lymphoplasmacytic lymphoma]

OBJECTIVE

To observe the clinical and biological characteristics of Non-IgM-secreting lymphoplasmacytic lymphoma (LPL) and draw the differences between non-IgM LPL and Waldenström macroglobulinemia (WM).

METHODS

Records of 13 patients with non-IgM LPL were retrospectively analyzed between January 2000 and December 2013. The cytogenetic aberrations were detected by fluorescence in situ hybridisation (FISH).

RESULTS

In the cohort, 7 males and 6 females with a median age of 63 years (range 43 to 74), two patients were IgA secreting, 6 with IgG secreting and 5 patients without monoclonal globulin. The major complaint at diagnosis included anemia associated symptom (53.8%), mucocutaneous hemorrhage and superficial lymphadenopathy (15.4%). Eight patients had B symptom at diagnosis. All of the 13 patients had bone marrow involvement and anemia, and 10 patients had 2 or 3 lineage cytopenia. In 5 patients with available immunophenotypic data, all expressed CD19, CD20, CD22 and CD25, but missed the expression of CD10, CD103 and CD38. Two cases had CD5 or sIgM positive alone. Another 2 patients were CD23 or CD11c positive and 3 patients were FMC7 positive. Cytogenetic aberrations had been detected by FISH in 7 patients, but only two (28.6%) patients had aberrations with del(6q).

CONCLUSION

The clinical and biological characteristics had no significantly difference between non-IgM LPL and WM.

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: What a hematologist needs to know

Waldenström macroglobulinemia (WM) is a distinct hematologic malignancy characterized by a lymphoplasmacytic bone marrow infiltration and the presence of immunoglobulin (Ig)M monoclonal protein. Patients typically present at an advanced age, and a substantial proportion are asymptomatic at diagnosis. A unifying diagnosis of WM may be missed by an unsuspecting hematologist, as symptomatic patients present with a multitude of non-specific manifestations. Although constitutional and neuropathy-related symptoms predominate, concomitant IgM-induced hyperviscosity-associated features can provide useful diagnostic clues. There are specific indications for initiation of therapy. This review focuses on the most up-to-date management strategies of WM, in addition to highlighting the recent discoveries of MYD88 and CXCR4 mutations that have shed unprecedented light on the complex signaling pathways, and opened avenues for novel therapeutic targeting. Although WM remains incurable, with the rapid emergence and integration of effective novel therapies, its clinical course appears poised to improve in the foreseeable future.

Immunophenotypic features by multiparameter flow cytometry can help distinguish low grade B-cell lymphomas with plasmacytic differentiation from plasma cell proliferative disorders with an unrelated clonal B-cell process

Highly sensitive flow cytometry studies may incidentally identify B cell clones when used to assess plasma cell clonality in bone marrows. Clinical history, which can help differentiate related clones (low grade B cell lymphoma with plasmacytic differentiation/LBCL-PD) from unrelated ones (plasma cell proliferative disorder (PCPD) with an unrelated B cell clone), is often unavailable in referred specimens. We sought to identify morphologic or phenotypic features that would help predict the significance of these clones in the absence of history. We included only cases with identical light chain B and plasma cell clones, as determined by 6-color flow cytometry with additional DNA ploidy analysis, in which the relationship between clones could be established by review of medical records. There were 26 cases; 18 were related (14 were Waldenstrom macroglobulinemia) and eight were unrelated (seven multiple myeloma). Features seen exclusively in LBCL-PD include CD19+/CD45+ clonal plasma cell phenotype (66·7%, P = 0·0022) and morphologic features such as paratrabecular bone marrow involvement, increased mast cells, and plasma cells surrounding B-cell nodules. Aneuploidy was identified exclusively in PCPD cases (75%, P = 0·000028). We conclude that CD19+/CD45+ clonal plasma cell phenotype and aneuploidy are useful in distinguishing related clones (LBCL-PD) from unrelated clones (PCPD).

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.

Lymphoplasmacytic lymphoma and Waldenström macroglobulinemia

Lymphoplasmacytic lymphoma (LPL) is a low-grade, B-cell neoplasm composed of small lymphocytes, plasmacytoid lymphocytes, and plasma cells that typically involve the bone marrow, and it is associated with an immunoglobulin M (IgM) gammopathy. The definition of Waldenström macroglobulinemia (WM) and its relationship to LPL has been confusing in the past. In addition, the diagnosis of LPL itself can be challenging because LPL lacks disease-specific morphologic, immunophenotypic, and genetic features to differentiate it from other mature B-cell neoplasms. Accurate diagnosis of LPL/WM rests on recognition of the differential diagnostic features between LPL and other diagnostic possibilities and the use of the recently refined definition of WM and its relationship with LPL: The presence of an IgM monoclonal gammopathy of any level in the setting of bone marrow involvement by LPL. This review summarizes the clinical, laboratory, and histologic features of LPL/WM, with particular emphasis on unique aspects of LPL/WM that may aid in accurate diagnosis.

Waldenström macroglobulinemia: a review of the entity and its differential diagnosis

The definition of Waldenström macroglobulinemia (WM), originally described in 1944, has been refined substantially over time. The current fourth edition of the World Health Organization of lymphoid neoplasms, in large part, adopted criteria proposed for WM at a consensus conference in 2002. WM is defined as lymphoplasmacytic lymphoma involving the bone marrow associated with a serum immunoglobulin (Ig) M paraprotein of any concentration. Morphologically, WM is composed of a variable mixture of lymphocytes, plasmacytoid lymphocytes, and plasma cells. Immunophenotypically, the neoplastic cells express monotypic IgM and light chain: B lymphocytes express pan-B-cell antigens and surface Ig are usually negative for CD5 and CD10; and plasma cells are typically positive for CD138, CD38, CD45, cytoplasmic Ig, and CD19 (in a substantial subset of cases). The putative cell of origin of WM is a postantigen selected memory B-cell that has undergone somatic hypermutation. The most common cytogenetic abnormality in WM is del(6q), usually in the region 6q23-24.3, present in 40% to 50% of cases. IGH gene translocations are rare and recurrent chromosomal translocations or gene aberrations have not been identified in WM. Here, we provide a historical perspective of WM, review clinical and pathologic aspects of the disease as it is currently defined, and discuss some practical issues in the differential diagnosis of WM that pathologists encounter in the signout of cases.

New insights into the pathogenesis and treatment of Waldenstrom macroglobulinemia

PURPOSE OF REVIEW

Waldenstrom macroglobulinemia is a distinct low-grade lymphoproliferative disease. There have been recent significant advances in understanding the underlying pathogenesis of this disease, including genetic and epigenetic regulators of tumor progression.

RECENT FINDINGS

Current studies have shown that the tumor microenvironment plays a critical role in cell proliferation, dissemination, and drug resistance.

SUMMARY

This review provides an update of the advances in the pathogenesis of factors both intrinsic (in the tumor clone) and extrinsic (in the bone marrow microenvironment) that regulate tumor progression in Waldenstrom macroglobulinemia. We next discuss novel agents that have been recently tested in clinical trials based on the advances observed in the pathogenesis of Waldenstrom macroglobulinemia.

CD5-positive chronic B-cell lymphoproliferative disorders: diagnosis and prognosis of a heterogeneous disease entity

BACKGROUND

The pathology and clinical course of patients with CD5+ chronic B-cell lymphoproliferative disorders, excluding those that present with typical chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) or mantle cell lymphoma, (i.e. CD5+B-CLPD) are poorly defined.

METHODS

We studied patients with CD5+B-CLPD to (1) more completely define the clinical features and pathology of CD5+B-CLPD, (2) compare these features to patients presenting with typical CLL, and (3) test the hypothesis that a subset of patients with CD5+B-CLPD could have a unique B-cell malignancy.

RESULTS

We identified 229 patients with CD5+B-CLPD. A definitive pathological diagnosis was made in all 61 (27%) CD5+B-CLPD patients with nonbone marrow (BM) biopsy specimens considered adequate for a comprehensive pathological examination. The most common diagnosis among these 61 patients was CLL (44%) followed by the leukemic phase of marginal zone lymphoma (34%), lymphoplasmacytic lymphoma (11%), diffuse large B cell lymphoma (8%), and high-grade B cell lymphoma not otherwise specified (2%). In contrast, among 168 patients without a non-BM tissue biopsy specimen, a specific diagnosis could be made on review of all available data in only 24 (14%) with 144 (86%) remaining "unclassified."

CONCLUSIONS

In patients with CD5+B-CLPD, a definitive diagnosis can be made on an adequate non-BM tissue biopsy suggesting that this entity does not include a novel disease. We recommend that all patients with CD5+B-CLPD should have a non-BM tissue biopsy to make a definitive diagnosis prior to initiation of treatment.

Rituximab and Subcutaneous 2-Chloro-2′-Deoxyadenosine Combination Treatment for Patients With Waldenström Macroglobulinemia: Clinical and Biologic Results of a Phase II Multicenter Study

Purpose

To assess the efficacy of 2-chloro-2′-deoxyadenosine (2-CdA) given subcutaneously (SC) in combination with rituximab in the treatment of newly diagnosed/pretreated patients with Waldenström macroglobulinemia (WM) and to correlate the response to treatment with biologic findings (immunophenotypic and pharmacogenomic analysis).

Patients and Methods

From December 2003 to February 2007, 29 patients were enrolled. Intended therapy consisted of a combination of rituximab (375 mg/m2) on day 1 followed by 2-CdA 0.1 mg/kg (SC injection) for 5 consecutive days, administered monthly for four cycles. Anemia (n = 16), neurologic symptoms (n = 6), symptomatic cryoglobulinemia (n = 4), and thrombocytopenia (n = 3) represented the reasons for starting treatment. The expression of ζ chain–associated protein kinase 70 (Zap-70) and of seven genes involved in 2-CdA metabolism as markers of response to the combination treatment was evaluated.

Results

With a median follow-up of 43 months, the overall response rate observed was 89.6%, with seven complete responses (CR), 16 partial responses, and three minor response, without any difference between newly or pretreated patients (P = .522). The therapy was well tolerated, except for transitory cardiac toxicity (n = 2) and intolerance to rituximab (n = 2). No major infections were observed despite the lack of antimicrobial prophylaxis. No patients developed transformation to high-grade non-Hodgkin's lymphoma nor myelodysplasia. Low expression levels of human concentrative nucleoside transporter 1 (hCNT1) were correlated with the failure to achieve a CR (P = .024), whereas no association with Zap-70 expression was found.

Conclusion

The combination of rituximab and SC 2-CdA is safe and effective in patients with WM requiring treatment. The pharmacogenomic analysis associated with the study suggests hCNT1 might be beneficial in predicting clinical response to such a combination treatment.

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.

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.

Flow cytometric immunophenotyping for hematologic neoplasms

Flow cytometric immunophenotyping remains an indispensable tool for the diagnosis, classification, staging, and monitoring of hematologic neoplasms. The last 10 years have seen advances in flow cytometry instrumentation and availability of an expanded range of antibodies and fluorochromes that have improved our ability to identify different normal cell populations and recognize phenotypic aberrancies, even when present in a small proportion of the cells analyzed. Phenotypically abnormal populations have been documented in many hematologic neoplasms, including lymphoma, chronic lymphoid leukemias, plasma cell neoplasms, acute leukemia, paroxysmal nocturnal hemoglobinuria, mast cell disease, myelodysplastic syndromes, and myeloproliferative disorders. The past decade has also seen refinement of the criteria used to identify distinct disease entities with widespread adoption of the 2001 World Health Organization (WHO) classification. This classification endorses a multiparametric approach to diagnosis and outlines the morphologic, immunophenotypic, and genotypic features characteristic of each disease entity. When should flow cytometric immunophenotyping be applied? The recent Bethesda International Consensus Conference on flow cytometric immunophenotypic analysis of hematolymphoid neoplasms made recommendations on the medical indications for flow cytometric testing. This review discusses how flow cytometric testing is currently applied in these clinical situations and how the information obtained can be used to direct other testing.

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.

Flow Cytometric Evaluation of B-cell Lymphoid Neoplasms

Evaluation of B-lymphocytes is one of the most well-established clinical applications of flow cytometric immunophenotyping. This article addresses general principles of the flow cytometric evaluation of B-cell lymphoid neoplasms, followed by discussion of how flow cytometric data can assist in determining a list of diagnostic possibilities and directing additional testing.

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.

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.

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.