Waldenstrom's Macroglobulinemia


Literature Analysis

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Tag cloud generated 08 August, 2015 using data from PubMed, MeSH and CancerIndex

Mutated Genes and Abnormal Protein Expression (15)

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MYD88 3p22 MYD88D -MYD88 and Waldenstrom's Macroglobulinemia
IGH 14q32.33 IGD1, IGH@, IGHJ, IGHV, IGHD@, IGHJ@, IGHV@, IGH.1@, IGHDY1 -IGH and Waldenstrom's Macroglobulinemia
CXCR4 2q21 FB22, HM89, LAP3, LCR1, NPYR, WHIM, CD184, LAP-3, LESTR, NPY3R, NPYRL, WHIMS, HSY3RR, NPYY3R, D2S201E -CXCR4 and Waldenstrom's Macroglobulinemia
HAS1 19q13.4 HAS -HAS1 and Waldenstrom's Macroglobulinemia
IL6 7p21 HGF, HSF, BSF2, IL-6, IFNB2 -IL6 and Waldenstrom's Macroglobulinemia
PTPRC 1q31-q32 LCA, LY5, B220, CD45, L-CA, T200, CD45R, GP180 -PTPRC and Waldenstrom's Macroglobulinemia
IRAK2 3p25.3 IRAK-2 -IRAK2 and Waldenstrom's Macroglobulinemia
HDAC4 2q37.3 HD4, AHO3, BDMR, HDACA, HA6116, HDAC-4, HDAC-A -HDAC4 and Waldenstrom's Macroglobulinemia
FCGR2B 1q23 CD32, FCG2, CD32B, FCGR2, IGFR2 -FCGR2B and Waldenstrom's Macroglobulinemia
EGLN1 1q42.1 HPH2, PHD2, SM20, ECYT3, HALAH, HPH-2, HIFPH2, ZMYND6, C1orf12, HIF-PH2 -EGLN1 and Waldenstrom's Macroglobulinemia
GZMB 14q11.2 HLP, CCPI, CGL1, CSPB, SECT, CGL-1, CSP-B, CTLA1, CTSGL1 -GZMB and Waldenstrom's Macroglobulinemia
EGLN3 14q13.1 PHD3, HIFPH3, HIFP4H3 -EGLN3 and Waldenstrom's Macroglobulinemia
IL4 5q31.1 BSF1, IL-4, BCGF1, BSF-1, BCGF-1 -IL4 and Waldenstrom's Macroglobulinemia
IRAK1 Xq28 IRAK, pelle -IRAK1 and Waldenstrom's Macroglobulinemia
CRP 1q23.2 PTX1 -CRP and Waldenstrom's Macroglobulinemia

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications

Rajkumar SV
Blood. 2015; 125(15):2318-9 [PubMed] Related Publications
In this issue of Blood, Paiva et al provide important information on the cell of origin in Waldenström macroglobulinemia (WM), a longstanding puzzle due to conflicting and incomplete data.

Martinez-Lopez A, Curiel-Olmo S, Mollejo M, et al.
MYD88 (L265P) somatic mutation in marginal zone B-cell lymphoma.
Am J Surg Pathol. 2015; 39(5):644-51 [PubMed] Related Publications
MYD88 L265P is a somatic mutation that has been identified in about 90% of Waldenström macroglobulinemia/lymphoplasmacytic lymphomas (LPLs). It has also been detected in a subset of marginal zone lymphoma (MZL) cases, but the frequency and clinical and histologic features of these mutated MZL cases has only been partially characterized. We have developed a customized TaqMan allele-specific polymerase chain reaction for sensitive detection of this mutation in paraffin-embedded tissue. We analyzed samples from 19 patients with LPL, 88 patients with splenic marginal zone lymphoma (SMZL), 8 patients with nodal marginal zone lymphoma (NMZL), 21 patients with extranodal mucosa-associated lymphoid tissue (MALT), and 2 patients with B-cell lymphoma not otherwise specified. By integrating mutational, histologic, and clinical data, 5 cases were reclassified as LPL. After reclassification, MYD88 L265P was detected in 13/86 (15%) SMZL and in 19/24 LPL (79%) cases. The mutation was absent from NMZL and MALT cases. A strong correlation was found between the presence of an IgM monoclonal paraproteinemia and the MYD88 L265P mutation (P<0.0001). SMZL cases positive for MYD88 L265P were also associated with monoclonal IgM paraproteinemia (4/13 cases; P<0.0283), although with less serum paraproteinemia. They also had a higher frequency of plasmacytic differentiation (9/13) but with no correlation between the presence of mutation and of light chain-restricted plasma cells in tissue. Demonstration of the MYD88 L265 mutation is a valuable tool for the diagnosis of LPL, although some SMZL cases carrying the mutation do not fulfill the diagnostic criteria for LPL.

Paiva B, Corchete LA, Vidriales MB, et al.
The cellular origin and malignant transformation of Waldenström macroglobulinemia.
Blood. 2015; 125(15):2370-80 [PubMed] Related Publications
Although information about the molecular pathogenesis of Waldenström macroglobulinemia (WM) has significantly advanced, the precise cell of origin and the mechanisms behind WM transformation from immunoglobulin-M (IgM) monoclonal gammopathy of undetermined significance (MGUS) remain undetermined. Here, we undertook an integrative phenotypic, molecular, and genomic approach to study clonal B cells from newly diagnosed patients with IgM MGUS (n = 22), smoldering (n = 16), and symptomatic WM (n = 11). Through principal component analysis of multidimensional flow cytometry data, we demonstrated highly overlapping phenotypic profiles for clonal B cells from IgM MGUS, smoldering, and symptomatic WM patients. Similarly, virtually no genes were significantly deregulated between fluorescence-activated cell sorter-sorted clonal B cells from the 3 disease groups. Interestingly, the transcriptome of the Waldenström B-cell clone was highly different than that of normal CD25(-)CD22(+) B cells, whereas significantly less genes were differentially expressed and specific WM pathways normalized once the transcriptome of the Waldenström B-cell clone was compared with its normal phenotypic (CD25(+)CD22(+low)) B-cell counterpart. The frequency of specific copy number abnormalities [+4, del(6q23.3-6q25.3), +12, and +18q11-18q23] progressively increased from IgM MGUS and smoldering WM vs symptomatic WM (18% vs 20% and 73%, respectively; P = .008), suggesting a multistep transformation of clonal B cells that, albeit benign (ie, IgM MGUS and smoldering WM), already harbor the phenotypic and molecular signatures of the malignant Waldenström clone.

Cao Y, Hunter ZR, Liu X, et al.
CXCR4 WHIM-like frameshift and nonsense mutations promote ibrutinib resistance but do not supplant MYD88(L265P) -directed survival signalling in Waldenström macroglobulinaemia cells.
Br J Haematol. 2015; 168(5):701-7 [PubMed] Related Publications
CXCR4(WHIM) frameshift and nonsense mutations follow MYD88(L265P) as the most common somatic variants in Waldenström Macroglobulinaemia (WM), and impact clinical presentation and ibrutinib response. While the nonsense (CXCR4(S338X) ) mutation has been investigated, little is known about CXCR4 frameshift (CXCR4(FS) ) mutations. We engineered WM cells to express CXCR4(FS) mutations present in patients, and compared their CXCL12 (SDF-1a) induced signalling and ibrutinib sensitivity to CXCR4(wild-type (WT)) and CXCR4(S338X) cells. Following CXCL12 stimulation, CXCR4(FS) and CXCR4(S338X) WM cells showed impaired CXCR4 receptor internalization, and enhanced AKT1 (also termed AKT) and MAPK1 (also termed ERK) activation versus CXCR(WT) cells (P < 0·05), though MAPK1 activation was more prolonged in CXCR4(S338X) cells (P < 0·05). CXCR4(FS) and CXCR4(S338X) cells, but not CXCR4(WT) cells, were rescued from ibrutinib-triggered apoptosis by CXCL12 that was reversed by AKT1, MAPK1 or CXCR4 antagonists. Treatment with an inhibitor that blocks MYD88(L265P) signalling triggered similar levels of apoptosis that was not abrogated by CXCL12 treatment in CXCR4(WT) and CXCR4(WHIM) cells. These studies show a functional role for CXCR4(FS) mutations in WM, and provide a framework for the investigation of CXCR4 antagonists with ibrutinib in CXCR4(WHIM) -mutated WM patients. Direct inhibition of MYD88(L265P) signalling overcomes CXCL12 triggered survival effects in CXCR4(WHIM) -mutated cells supporting a primary role for this survival pathway in WM.

Petrikkos L, Kyrtsonis MC, Roumelioti M, et al.
Clonotypic analysis of immunoglobulin heavy chain sequences in patients with Waldenström's macroglobulinemia: correlation with MYD88 L265P somatic mutation status, clinical features, and outcome.
Biomed Res Int. 2014; 2014:809103 [PubMed] Free Access to Full Article Related Publications
We performed IGH clonotypic sequence analysis in WM in order to determine whether a preferential IGH gene rearrangement was observed and to assess IGHV mutational status in blood and/or bone marrow samples from 36 WM patients. In addition we investigated the presence of MYD88 L265P somatic mutation. After IGH VDJ locus amplification, monoclonal VDJ rearranged fragments were sequenced and analyzed. MYD88 L265P mutation was detected by AS-PCR. The most frequent family usage was IGHV3 (74%); IGHV3-23 and IGHV3-74 segments were used in 26% and 17%, respectively. Somatic hypermutation was seen in 91% of cases. MYD88 L265P mutation was found in 65,5% of patients and absent in the 3 unmutated. These findings did not correlate with clinical findings and outcome. Conclusion. IGH genes' repertoire differed in WM from those observed in other B-cell disorders with a recurrent IGHV3-23 and IGHV3-74 usage; monoclonal IGHV was mutated in most cases, and a high but not omnipresent prevalence of MYD88 L265P mutation was observed. In addition, the identification of 3 patients with unmutated IGHV gene segments, negative for the MYD88 L265P mutation, could support the hypothesis that an extra-germinal B-cell may represent the originating malignant cell in this minority of WM patients.

Poulain S, Boyle EM, Roumier C, et al.
MYD88 L265P mutation contributes to the diagnosis of Bing Neel syndrome.
Br J Haematol. 2014; 167(4):506-13 [PubMed] Related Publications
Bing-Neel syndrome (BNS), a rare neurological syndrome associated with Waldenström macroglobulinaemia (WM), is a direct involvement of the central nervous system by lymphoplasmacytoid cells characterized with an adverse prognostic. The MYD88 L265P mutation has been identified in the vast majority of patients with WM. The diagnosis of BNS is often challenging because of the variety of clinical presentations associated with difficult histological techniques. We hypothesized that identification of MYD88 L265P mutation in the cerebrospinal fluid (CSF) would contribute to the diagnosis of BNS in addition to imaging, flow cytometry and cytology. We identified MYD88 L265P mutation in the CSF and the bone marrow of all cases of BNS using quantitative polymerase chain reaction qPCR and Sanger sequencing. Copy neutral loss of heterozygosity including MYD88 was observed in one case. No mutation of CXCR4, CD79A and CD79B was observed in parallel. We further showed that monitoring the quantitative expression of MYD88 L265P mutation might be a useful molecular tool to monitor response to chemotherapy using qPCR. In conclusion, identification of MYD88 L265P mutation might be a new molecular-based biomarker tool to add to the diagnostic and monitoring armamentarium for BNS.

Kim JA, Im K, Park SN, et al.
MYD88 L265P mutations are correlated with 6q deletion in Korean patients with Waldenström macroglobulinemia.
Biomed Res Int. 2014; 2014:363540 [PubMed] Free Access to Full Article Related Publications
Waldenström macroglobulinemia (WM) is a malignant lymphoplasma-proliferative disorder with IgM monoclonal gammopathy. A recent whole-genome study identified MYD88 L265P as the key mutation in WM. We investigated MYD88 mutations in conjunction with cytogenetic study in 22 consecutive Korean WM patients. Conventional G-banding and interphase fluorescence in situ hybridization (FISH) were performed at regions including 6q21 using bone marrow (BM) aspirates. Sixteen patients were subjected to Sanger sequencing-based MYD88 mutation study. Five patients (28%) showed cytogenetic aberrations in G-banding. The incidence of 6q21 deletion was 17% by conventional G-banding and 37% by FISH. Ten patients (45%) showed cytogenetic aberrations using FISH: 6q deletion in eight (37%) and IGH rearrangement in four (18%). Two patients had both the 6q deletion and IGH rearrangement, and two had only the IGH rearrangement. Eleven patients (69%) presented with the MYD88 L265P mutation. MYD88 mutations were significantly associated with the presence of 6q deletions (P = 0.037). Six patients with the 6q deletion for whom sequencing was possible were found to harbor MYD88 mutations. The MYD88 L265P mutation was also associated with increased lymphocyte burden in BM biopsy. This is the first report of high frequency MYD88 L265P mutations in Korean WM patients.

Capaldi IB, May AM, Schmitt-Graeff A, et al.
Detection of MYD88 L265P mutations in formalin-fixed and decalcified BM biopsies from patients with lymphoplasmacytic lymphoma.
Exp Mol Pathol. 2014; 97(1):57-65 [PubMed] Related Publications
The diagnosis of bone marrow (BM) infiltration by Waldenström macroglobulinemia (WM)/lymphoplasmacytic lymphoma (LPL) poses a diagnostic challenge in hematopathology. No definitive morphology or immunophenotype is able to distinguish between infiltration of paraffin-embedded BM sections by WM/LPL and other indolent lymphomas, in particular those of the splenic marginal zone (SMZL) which may also show plasmacytic maturation. An oncogenic gain-of-function mutation (L265P) in the human MYD88 gene has been found to be present in most cases of WM/LPL, yet is absent in most other cases of B-cell chronic lymphoproliferative disorders (LPD), including SMZL. Here, we compare two newly developed diagnostic protocols for detection of this mutation in paraffin-embedded archival tissues which are particularly applicable to decalcified BM biopsies. Sanger sequencing can easily detect levels of BM infiltration above 15% by WM lymphoplasmacytic cells, while the allele-specific PCR can detect the L265P mutation in BM infiltrations below 1% of lymphoma cells. We show that these methods are easily applicable to archival BM specimens and markedly improve diagnostic accuracy of BM infiltrations by indolent B-cell lymphomas.

Zhou Y, Liu X, Xu L, et al.
Transcriptional repression of plasma cell differentiation is orchestrated by aberrant over-expression of the ETS factor SPIB in Waldenström macroglobulinaemia.
Br J Haematol. 2014; 166(5):677-89 [PubMed] Related Publications
In Waldenström macroglobulinaemia (WM), the mechanism(s) responsible for repression of B-cell differentiation remains unknown. We found that expression of SPIB and ID2 were significantly increased and decreased, respectively, in WM lymphoplasmacytic cells (LPC). Ectopic expression of SPIB in healthy donor CD19(+) cells inhibited plasmacytic differentiation in conjunction with decreased transcription of IRF4 and XBP1 spliced form. In primary WM LPC, knock-down of SPIB induced plasmacytic differentiation in conjunction with increased transcription of PRDM1, XBP1 spliced form, IRF4 and ID2. Knock-down of SPIB also led to decreased BCL2 expression. Given that SPIB is a direct target of POU2AF1 (OBF1) in complex with POU2F2 or POU2F1, we next examined their expression in WM LPC. POU2F2 transcription, as well as POU2F2 and POU2AF1 protein expression was higher in WM LPC. Ectopic expression of POU2F2 in healthy donor CD19(+) cells induced transcription of SPIB and suppressed transcription of PRDM1 and IRF4. Chromatin immunoprecipitation analysis in BCWM.1 WM cells confirmed binding of POU2F2 and POU2AF1 in SPIB and ID2 promoters. These findings establish a molecular hierarchy among POU2F2, SPIB and ID2 during B-cell differentiation, and suggest that aberrant expression of these transcription factors plays an important role in arresting plasmacytic differentiation in WM.

Lenz G
Waldenstrom macroglobulinemia: genetics dictates clinical course.
Blood. 2014; 123(18):2750-1 [PubMed] Related Publications
In this issue of Blood, Treon and colleagues provide strong evidence that mutations in MYD88 and CXCR4 dictate clinical presentation and survival in Waldenström macroglobulinemia (WM).

Sakata-Yanagimoto M, Enami T, Yokoyama Y, Chiba S
Disease-specific mutations in mature lymphoid neoplasms: recent advances.
Cancer Sci. 2014; 105(6):623-9 [PubMed] Related Publications
Mature lymphoid neoplasms (MLN) are clinically and pathologically more complex than precursor lymphoid neoplasms. Until recently, molecular characterization of MLN was mainly based on cytogenetics/fluorescence in situ hybridization, allele copy number, and mRNA expression, approaches that yielded scanty gene mutation information. Use of massive parallel sequencing technologies has changed this outcome, and now many gene mutations have been discovered. Some of these are considerably frequent in, and substantially specific to, distinct MLN subtypes, and occur at single or several hotspots. They include the V600E BRAF mutation in hairy cell leukemia, the L265P MYD88 mutation in Waldenström macroglobulinemia, the G17V RHOA mutation in angioimmunoblastic T-cell lymphoma and peripheral T-cell lymphoma, not otherwise specified, and the Y640F//D661Y/V/H/I//N647I STAT3 mutations in T-cell large granular lymphocytic leukemia. Detecting these mutations is highly valuable in diagnosing MLN subtypes. Defining these mutations also sheds light on the molecular pathogenesis of MLN, furthering development of molecular targeting therapies. In this review, we focus on the disease-specific gene mutations in MLN discovered by recent massive sequencing technologies.

Landgren O, Tageja N
MYD88 and beyond: novel opportunities for diagnosis, prognosis and treatment in Waldenström's Macroglobulinemia.
Leukemia. 2014; 28(9):1799-803 [PubMed] Related Publications
Waldenström's Macroglobulinemia (WM) is a rare disease of the elderly with a median age of 63-68 years at diagnosis. Despite recent progress in biological insights and therapeutics, WM remains clinically challenging to diagnose and is difficult to manage with significant morbidity and lack of established curative therapies. Recently, the use of whole-genome sequencing has helped to identify a highly recurrent somatic mutation, myeloid differentiation factor 88 [MYD88] L265P in WM. This has fueled major interest in the field and as newer evidence accumulates, it is clear that that discovery of MYD88 L265P mutation may represent an important breakthrough in understanding the pathogenesis of WM and lymphoproliferative disorders. Recent scientific work in this field has also guided the identification of new targets such as CXCR4 and PI3K-delta that may have major implications in the future treatment of WM. This review discusses the role of MYD88 L265P mutations as well as targets beyond MYD88 in the setting of pathogenesis and development of future rational therapeutic trials focusing on patients diagnosed with WM.

Treon SP, Cao Y, Xu L, et al.
Somatic mutations in MYD88 and CXCR4 are determinants of clinical presentation and overall survival in Waldenstrom macroglobulinemia.
Blood. 2014; 123(18):2791-6 [PubMed] Related Publications
Whole genome sequencing has revealed activating somatic mutations in MYD88 (L265P) and CXCR4 in Waldenström macroglobulinemia (WM). CXCR4 somatic mutations in WM are the first ever reported in human cancer and are similar to nonsense (NS) and frameshift (FS) germline mutations found in warts, hypogammaglobulinemia, infections and myelokathexis (WHIM) syndrome. We genotyped lymphoplasmacytic cells from 175 WM patients and observed significantly higher bone marrow (BM) disease involvement, serum immunoglobulin-M levels, and symptomatic disease requiring therapy, including hyperviscosity syndrome in those patients with MYD88(L265P)CXCR4(WHIM/NS) mutations (P < .03). Patients with MYD88(L265P)CXCR4(WHIM/FS) or MYD88(L265P)CXCR4(WILDTYPE (WT)) had intermediate BM and serum immunoglobulin-M levels; those with MYD88(WT)CXCR4(WT) showed lowest BM disease burden. Fewer patients with MYD88(L265P) and CXCR4(WHIM/FS or NS) vs MYD88(L265P)CXCR4(WT) presented with adenopathy (P < .01), further delineating differences in disease tropism based on CXCR4 status. Neither MYD88 nor CXCR4 mutations correlated with SDF-1a (RS1801157) polymorphisms in 54 patients who were genotyped for these variants. Unexpectedly, risk of death was not impacted by CXCR4 mutation status, but by MYD88(WT) status (hazard ratio 10.54; 95% confidence interval 2.4-46.2, P = .0018). Somatic mutations in MYD88 and CXCR4 are important determinants of clinical presentation and impact overall survival in WM. Targeted therapies directed against MYD88 and/or CXCR4 signaling may provide a personalized treatment approach to WM.

Xu L, Hunter ZR, Yang G, et al.
Detection of MYD88 L265P in peripheral blood of patients with Waldenström's Macroglobulinemia and IgM monoclonal gammopathy of undetermined significance.
Leukemia. 2014; 28(8):1698-704 [PubMed] Related Publications
MYD88 L265P is highly prevalent in Waldenstrom's Macroglobulinemia (WM) and IgM monoclonal gammopathy of unknown significance (MGUS). We investigated whether MYD88 L265P could be identified by peripheral blood (PB) allele-specific PCR. MYD88 L265P was detected in untreated WM (114/118; 96.6%); previously treated WM (63/102; 61.8%); and IgM MGUS (5/12; 41.7%) but in none of 3 hyper-IgM or 40 healthy individuals. Median PB MYD88 L265P ΔCt was 3.77, 7.24, 10.89, 12.33 and 14.07 for untreated WM, previously treated WM, IgM MGUS, hyper-IgM and healthy individuals, respectively (P<0.0001). For the 232 IgM MGUS and WM patients, PB MYD88 L265P ΔCt moderately correlated to bone marrow (BM) disease (r=-0.3553; P<0.0001), serum IgM (r=-0.3262; P<0.0001) and hemoglobin (r=0.3005; P<0.0001) levels. PB MYD88 L265P ΔCt and serum IgM correlated similarly with BM disease burden. For positive patients, PB MYD88 L265P ΔCt was <6.5 in 100/114 (88%) untreated WM, and >6.5 in 4/5 (80%) IgM MGUS patients (P=0.0034). Attainment of a negative PB MYD88 L265P mutation status was associated with lower BM disease (P=0.001), serum IgM (P=0.019) and higher hemoglobin (P=0.004) levels in treated patients. These studies show the feasibility for detecting MYD88 L265P by PB examination, and the potential for PB MYD88 L265P ΔCt use in the diagnosis and management of WM patients.

Hunter ZR, Xu L, Yang G, et al.
The genomic landscape of Waldenstrom macroglobulinemia is characterized by highly recurring MYD88 and WHIM-like CXCR4 mutations, and small somatic deletions associated with B-cell lymphomagenesis.
Blood. 2014; 123(11):1637-46 [PubMed] Related Publications
The genetic basis for Waldenström macroglobulinemia (WM) remains to be clarified. Although 6q losses are commonly present, recurring gene losses in this region remain to be defined. We therefore performed whole genome sequencing (WGS) in 30 WM patients, which included germline/tumor sequencing for 10 patients. Validated somatic mutations occurring in >10% of patients included MYD88, CXCR4, and ARID1A that were present in 90%, 27%, and 17% of patients, respectively, and included the activating mutation L265P in MYD88 and warts, hypogammaglobulinemia, infection, and myelokathexis-syndrome-like mutations in CXCR4 that previously have only been described in the germline. WGS also delineated copy number alterations (CNAs) and structural variants in the 10 paired patients. The CXCR4 and CNA findings were validated in independent expansion cohorts of 147 and 30 WM patients, respectively. Validated gene losses due to CNAs involved PRDM2 (93%), BTG1 (87%), HIVEP2 (77%), MKLN1 (77%), PLEKHG1 (70%), LYN (60%), ARID1B (50%), and FOXP1 (37%). Losses in PLEKHG1, HIVEP2, ARID1B, and BCLAF1 constituted the most common deletions within chromosome 6. Although no recurrent translocations were observed, in 2 patients deletions in 6q corresponded with translocation events. These studies evidence highly recurring somatic events, and provide a genomic basis for understanding the pathogenesis of WM.

Hodge LS, Ziesmer SC, Yang ZZ, et al.
Constitutive activation of STAT5A and STAT5B regulates IgM secretion in Waldenstrom's macroglobulinemia.
Blood. 2014; 123(7):1055-8 [PubMed] Free Access to Full Article Related Publications
Activation of the Janus kinase family/signal transducer and activator of transcription (JAK/STAT) signaling pathway has been associated with the pathogenesis and progression of both solid and hematologic malignancies. We have detected constitutive activation of STAT5 in malignant B cells derived from patients with Waldenström's macroglobulinemia (WM). Although short hairpin RNA-mediated knockdown of the STAT5A and STAT5B isoforms did not affect cellular proliferation, loss of STAT5 significantly decreased immunoglobulin M (IgM) secretion. A similar dose-dependent inhibition of IgM secretion was observed when WM cell lines were treated with a small molecule inhibitor of STAT5. These data suggest that STAT5 is involved in regulating IgM production in WM and that inhibition of STAT5 may represent a novel therapeutic strategy for lowering IgM levels in WM patients.

Mori N, Ohwashi M, Yoshinaga K, et al.
L265P mutation of the MYD88 gene is frequent in Waldenström's macroglobulinemia and its absence in myeloma.
PLoS One. 2013; 8(11):e80088 [PubMed] Free Access to Full Article Related Publications
L265P mutation in the MYD88 gene has recently been reported in Waldenström's macroglobulinemia; however the incidence has been different according to the methods used. To determine the relevance and compare the incidence by different methods, we analyzed the L265P mutation in bone marrow mononuclear cells from lymphoid neoplasms. We first performed cloning and sequencing in 10 patients: 8 Waldenström's macroglobulinemia; 1 non-IgM-secreting lymphoplasmacytic lymphoma; and 1 low grade B-cell lymphoma with monoclonal IgG protein. The L265P mutation was detected in only 1/8 Waldenström's macroglobulinemia patients (2 of 9 clones). To confirm these results, direct sequencing was performed in the 10 patients and an additional 17 Waldenström's macroglobulinemia patients and 1 lymphoplasmacytic lymphoma patient. Nine of 28 patients (7/25 Waldenström's macroglobulinemia, 1/2 lymphoplasmacytic lymphoma, and B-cell lymphoma) harbored the mutation. We next tested for the mutation with BSiE1 digestion and allele-specific polymerase chain reaction in the 28 patients and 38 patients with myeloma. Aberrant bands corresponding to the mutation were detected by BSiE1 digestion in 19/25 patients with Waldenström's macroglobulinemia (76%), 1/2 lymphoplasmacytic lymphoma and B-cell lymphoma, but not in the 38 myeloma patients. The L265P mutation was more frequent in patients with Waldenström's macroglobulinemia than in those with myeloma (p=1.3x10(-10)). The mutation was detected by allele-specific polymerase chain reaction in 18/25 Waldenström's macroglobulinemia patients (72%). In the 25 Waldenström's macroglobulinemia patients, the L265P was more frequently detected by BSiE1 digestion than by direct sequencing (p=5.3x10(-4)), and in males (15/16, 94%) than in females (4/9, 44%) (p=1.2x10(-2)). No siginificant difference was observed in the incidence of the L265P mutation between BSiE1 digestion and allele-specific polymerase chain reaction (p=0.32). These results suggest that the L265P mutation is involved in the majority of Waldenström's macroglobulinemia. BSiE1 digestion and allele-specific polymerase chain reaction may detect a small fraction of mutated cells in some cases.

Morra E, Varettoni M, Tedeschi A, et al.
Associated cancers in Waldenström macroglobulinemia: clues for common genetic predisposition.
Clin Lymphoma Myeloma Leuk. 2013; 13(6):700-3 [PubMed] Related Publications
BACKGROUND: Several population-based and cohort studies have reported an increased risk of second cancers in lymphoproliferative disorders (LPDs). The cause of second cancers in LPDs is probably multifactorial, and the relative contribution of treatments, genetic predisposition, and immune dysfunction typical of LPDs is still unclear.
PATIENTS AND METHODS: We retrospectively studied 230 patients with Waldenström macroglobulinemia (WM) to assess the frequency, characteristics, and predictive factors of second cancers and to evaluate whether patients with WM are at higher risk of second cancers compared with an age- and sex-matched control population.
RESULTS: In a competing-risk model, the cumulative incidence of solid cancers was 6% at 5 years, 11% at 10 years, and 17% at 15 years, whereas the incidence of hematologic malignancies was 4% at 5 years, 7% at 10 years, and 8% at 15 years. Compared with an age- and sex-matched population, the overall risk of second cancers was 1.7-fold higher than expected (95% confidence interval [CI], 1.22-2.38; P = .002). Patients with WM were at increased risk for diffuse large B-cell lymphoma (DLBCL) (standardized incidence ratio [SIR], 8.64; 95% CI, 3.88-19.22; P < .0001), myelodysplastic syndrome/acute myeloid leukemia (MDS/AML) (SIR 9.5; 95% CI, 3.6-25.3; P < .0001), and brain cancer (SIR, 7.59; 95% CI, 1.9-30.4; P < .0001). The risk of a second hematologic malignancy was 5-fold higher in treated than in untreated patients (P = .08).
CONCLUSION: Patients with WM are at increased risk of DLBCL, MDS/AML, and brain cancers compared with the general population. Further studies are needed to clarify whether the increased incidence of second cancers is related to treatments, to the immunologic impairment associated with the disease, or to genetic predisposition.

Monge J, Braggio E, Ansell SM
Genetic factors and pathogenesis of Waldenström's macroglobulinemia.
Curr Oncol Rep. 2013; 15(5):450-6 [PubMed] Free Access to Full Article Related Publications
Waldenström's macroglobulinemia (WM) is an indolent but incurable B-cell malignancy. Over the last decade, advances in the molecular field brought about by the use of high-throughput genomic analyses-including array-based comparative genomic hybridization and massively parallel genome sequencing-have considerably improved our understanding of the genetic basis of WM. Its pathogenesis, however, remains fragmented. Important steps have been made in elucidating the underlying aberrations and deregulated mechanisms of the disease, and thereby providing invaluable information for identifying biomarkers for disease diagnosis, risk stratification, and therapeutic approaches. We review the genetic basis of the disease.

Poulain S, Roumier C, Galiègue-Zouitina S, et al.
Genome wide SNP array identified multiple mechanisms of genetic changes in Waldenstrom macroglobulinemia.
Am J Hematol. 2013; 88(11):948-54 [PubMed] Related Publications
SNP array (SNPa) was developed to detect copy number alteration (CNA) and loss of heterozygosity (LOH) without copy number changes, CN-LOH. We aimed to identify novel genomic aberrations using SNPa in 31 WM with paired samples. Methylation status and mutation were analyzed on target genes. A total of 61 genetic aberrations were observed, 58 CNA (33 gains, 25 losses) in 58% of patients and CN-LOH in 6% of patients. The CNA were widely distributed throughout the genome, including 12 recurrent regions and identified new cryptic clonal chromosomal lesions that were mapped. Gene set expression analysis demonstrated a relationship between either deletion 6q or gain of chromosome 4 and alteration of gene expression profiling. We then studied methylation status and sought for mutations in altered regions on target genes. We observed methylation of DLEU7 on chromosome 13 in all patients (n = 12) with WM, and mutations of CD79B/CD79A genes (17q region), a key component of the BCR pathway, in 15% of cases. Most importantly, higher frequency of ≥3 CNA was observed in symptomatic WM. In conclusion, this study expands the view of the genomic complexity of WM, especially in symptomatic WM, including a potentially new mechanism of gene dysfunction, acquired uniparental disomy/CN-LOH. Finally, we have identified new potential target genes in WM, such as DLEU7 and CD79A/B.

Treon SP, Hunter ZR
A new era for Waldenstrom macroglobulinemia: MYD88 L265P.
Blood. 2013; 121(22):4434-6 [PubMed] Related Publications
In this issue of Blood, Poulain et al demonstrate the high prevalence of the MYD88 L265P somatic mutation in patients with Waldenstrom macroglobulinemia (WM) and provide insight into its biological relevance in the growth and survival of WM.

Poulain S, Roumier C, Decambron A, et al.
MYD88 L265P mutation in Waldenstrom macroglobulinemia.
Blood. 2013; 121(22):4504-11 [PubMed] Related Publications
Mutation of the MYD88 gene has recently been identified in activated B-cell-like diffuse cell lymphoma and enhanced Janus kinase/signal transducer and activator of transcription (JAK-STAT) and nuclear factor κB (NF-κB) signaling pathways. A whole exome-sequencing study of Waldenstrom macroglobulinemia (WM) suggested a high frequency of MYD88 L265P mutation in WM. The genetic background is not fully deciphered in WM, although the role of NF-κB and JAK-STAT has been demonstrated. We analyzed MYD88 mutation in exon 5 and characterized the clinical significance of this genetic alteration in 67 WM patients. Clinical features; immunophenotypic markers; and conventional cytogenetic, fluorescence in situ hybridization, and single nucleotide polymorphism array data were analyzed. MYD88 L265P mutation was acquired in 79% of patients. Overall, we have identified alteration of the MYD88 locus in 91% of WM patients, including 12% with gain on chromosome 3 at the 3p22 locus that included the MYD88 gene. Patients with absence of MYD88 mutation were WM characterized with a female predominance, a splenomegaly, gain of chromosome 3, and CD27 expression. Importantly, inhibition of MYD88 signaling induced cytotoxicity and inhibited cell growth of cell lines issued from patients with WM. In conclusion, these results confirm a high frequency of MYD88 L265P mutation in WM. The discovery of MYD88 L265P mutation may contribute to a better understanding of the physiopathogeny of WM.

Braggio E, Fonseca R
Genomic abnormalities of Waldenström macroglobulinemia and related low-grade B-cell lymphomas.
Clin Lymphoma Myeloma Leuk. 2013; 13(2):198-201 [PubMed] Related Publications
Waldenström macroglobulinemia (WM) is a lymphoproliferative disease characterized by a heterogeneous lymphoplasmacytic bone marrow infiltrate and monoclonal immunoglobulin M production. WM shows similarities in presentations with related B-cell malignancies, sometimes making it difficult to distinguish them. To better characterize the genetic basis of WM, we performed a comparative genomic analysis with the related entities, lymphoplasmacytic lymphomas without monoclonal immunoglobulin M protein, marginal zone lymphomas, chronic lymphocytic leukemia, and monoclonal gammopathy of undetermined significance. Overall, WM shows a very stable karyotype and shares most of the chromosomal abnormalities with most of the indolent B-cell malignancies. Trisomy 4 is unique to WM; however, no candidate genes have been identified in the chromosome. Abnormalities that affect myeloid differentiation primary response 88 (MYD88)--interleukin-1 receptor-associated kinase 4 (IRAK4) and nuclear factor kappa B (NF-κB) signaling pathways were found in a significant proportion of WM cases, which suggest their relevance in the pathogenesis of the disease and opening new avenues that may be a guide to design novel therapeutic approaches.

Trojani A, Greco A, Tedeschi A, et al.
Microarray demonstrates different gene expression profiling signatures between Waldenström macroglobulinemia and IgM monoclonal gammopathy of undetermined significance.
Clin Lymphoma Myeloma Leuk. 2013; 13(2):208-10 [PubMed] Related Publications
Waldenström macroglobulinemia (WM) (symptomatic and indolent) and immunoglobulin M (IgM) monoclonal gammopathy of undetermined significance (IgMMGUS) can be identified based on the bone marrow (BM) infiltration and the existence of symptoms. The purpose of this study was to investigate the biological and genetic characteristics of both disorders comparing the molecular signature of WM versus IgMMGUS using microarray analysis. We investigated BM CD19(+) cells isolated from 21 WM patients and 10 IgMMGUS cases, and CD138(+) BM cells isolated from all of the WM patients and 4 of the IgMMGUS cases. Gene expression profiling of WM versus IgMMGUS CD19(+) cells highlighted 151 differently expressed genes and the comparison with CD138(+) cells demonstrated 43 differently expressed genes in WM versus IgMMGUS. Regulation of transcription, Janus kinase/signal transducer and activator of transcription, PI3K/Akt/mammalian target of rapamycin, mitogen-activated protein kinase signaling pathways are the relevant gene ontology biological processes occurring in CD19(+) cells, and immune response, cell activation, and signaling processes developing in CD138(+) cells mainly distinguish WM and IgMMGUS.

Sacco A, Zhang Y, Maiso P, et al.
microRNA aberrations in Waldenström macroglobulinemia.
Clin Lymphoma Myeloma Leuk. 2013; 13(2):205-7 [PubMed] Related Publications
Waldenström macroglobulinemia (WM) is a low-grade B-cell lymphoma characterized by the presence of lymphoplasmacytic cells in the BM (BM) and monoclonal immunoglobulin M in the circulation. Although WM cells showed minimal changes in cytogenetic studies and gene expression analysis, primary WM tumor cells present with a micro-RNA (miRNA) signature that differentiates them from their normal counterparts. This may suggest the importance of miRNAs in supporting WM pathogenesis. Among deregulated miRNAs, miRNA-155 has been shown to play a pivotal role in the biological characteristics of this disease both in vitro and in vivo, thus providing the rationale for testing miRNA-based therapeutic approaches for the treatment of WM.

Poulain S, Herbaux C, Bertrand E, et al.
Genomic studies have identified multiple mechanisms of genetic changes in Waldenström macroglobulinemia.
Clin Lymphoma Myeloma Leuk. 2013; 13(2):202-4 [PubMed] Related Publications
The pathophysiology of Waldenström macroglobulinemia (WM), a lymphoproliferative disorder characterized by lymphoplasmacytic bone marrow infiltration associated with serum IgM paraprotein, is rather unclear; however, progress has been made in recent years to better determine the genetic profile of WM tumor cells. Studies based on high-throughput genomic analyses-including single-nucleotide polymorphism array (SNPa), array-based comparative genomic hybridization, and, recently, whole-genome sequencing--have improved deciphering some of the key molecular pathways associated with WM. Beyond the discovery of the myeloid differentiation primary response gene 88 (MYD88) L265P mutation, which will help greatly in the differential characterization of WM from other B-cell low-grade lymphomas, several other mechanisms of gene deregulation were identified and mapped that recurrently pointed out nuclear factor-kappa B (NF-κB), breakpoint cluster region (BCR), and Toll-like receptor (TLR) signaling pathways as potential targets for a better understanding of the physiopathology of WM and for future drug development. Herein, we summarize the current knowledge of the genomic patterns of WM to highlight its complexity.

Jiménez C, Sebastián E, Chillón MC, et al.
MYD88 L265P is a marker highly characteristic of, but not restricted to, Waldenström's macroglobulinemia.
Leukemia. 2013; 27(8):1722-8 [PubMed] Related Publications
We evaluated the MYD88 L265P mutation in Waldenström's macroglobulinemia (WM) and B-cell lymphoproliferative disorders by specific polymerase chain reaction (PCR) (sensitivity ∼10(-3)). No mutation was seen in normal donors, while it was present in 101/117 (86%) WM patients, 27/31 (87%) IgM monoclonal gammapathies of uncertain significance (MGUS), 3/14 (21%) splenic marginal zone lymphomas and 9/48 (19%) non-germinal center (GC) diffuse large B-cell lymphomas (DLBCLs). The mutation was absent in all 28 GC-DLBCLs, 13 DLBCLs not subclassified, 35 hairy cell leukemias, 39 chronic lymphocytic leukemias (16 with M-component), 25 IgA or IgG-MGUS, 24 multiple myeloma (3 with an IgM isotype), 6 amyloidosis, 9 lymphoplasmacytic lymphomas and 1 IgM-related neuropathy. Among WM and IgM-MGUS, MYD88 L265P mutation was associated with some differences in clinical and biological characteristics, although usually minor; wild-type MYD88 cases had smaller M-component (1.77 vs 2.72 g/dl, P=0.022), more lymphocytosis (24 vs 5%, P=0.006), higher lactate dehydrogenase level (371 vs 265 UI/L, P=0.002), atypical immunophenotype (CD23-CD27+ +FMC7+ +), less Immunoglobulin Heavy Chain Variable gene (IGHV) somatic hypermutation (57 vs 97%, P=0.012) and less IGHV3-23 gene selection (9 vs 27%, P=0.014). These small differences did not lead to different time to first therapy, response to treatment or progression-free or overall survival.

Varettoni M, Zibellini S, Capello D, et al.
Clues to pathogenesis of Waldenström macroglobulinemia and immunoglobulin M monoclonal gammopathy of undetermined significance provided by analysis of immunoglobulin heavy chain gene rearrangement and clustering of B-cell receptors.
Leuk Lymphoma. 2013; 54(11):2485-9 [PubMed] Related Publications
We characterized immunoglobulin heavy chain (IGH) gene rearrangements and searched for clusters of stereotyped B-cell receptors in 123 patients with Waldenström macroglobulinemia (WM; n = 59) or immunoglobulin M monoclonal gammopathy of undetermined significance (IgM-MGUS) (n = 64). A productive monoclonal IGHV-D-J rearrangement was obtained in 99/123 patients (80%). Immunoglobulin heavy chain variable (IGHV) genes were mutated in 94/99 patients (95%) with a median somatic hypermutation rate of 6.7% (2.1-14.5). Compared with the normal B-cell repertoire, patients with WM/IgM-MGUS showed an over-representation of the IGHV3 subgroup (83% vs. 55%, p < 0.0001) and an under-representation of IGHV1 (7% vs. 14%, p = 0.04) and IGHV4 (7% vs. 23%, p = 0.0001) subgroups. At the gene level, in WM/IgM-MGUS there was an over-representation of IGHV3-23 (24% vs. 12%, p = 0.0003), IGHV3-64 (3% vs. < 1%, p = 0.003), IGHV3-7 (12% vs. 4%, p = 0.0001) and IGHV3-74 (9% vs. 2%, p < 0.0001), while IGHV4-39 was never used (0 vs. 5%, p = 0.03). Intra-WM/IgM-MGUS search for HCDR3 similarity showed no association fulfilling criteria for stereotyped receptors. WM/IgM-MGUS sequences were unrelated to known chronic lymphocytic leukemia (CLL), splenic marginal zone lymphoma (SMZL) or mantle cell lymphoma (MCL) subsets. In conclusion, the IGHV gene usage in WM and IgM-MGUS is remarkably biased as compared to the normal B-cell repertoire. WM and IgM-MGUS-specific HCDR3 clusters do not occur with a frequency detectable with currently available databases, not supporting a B-cell receptor-driven pathogenesis in WM and IgM-MGUS.

Varettoni M, Arcaini L, Zibellini S, et al.
Prevalence and clinical significance of the MYD88 (L265P) somatic mutation in Waldenstrom's macroglobulinemia and related lymphoid neoplasms.
Blood. 2013; 121(13):2522-8 [PubMed] Related Publications
A study has shown that MYD88 (L265P) is a recurring somatic mutation in Waldenström's macroglobulinemia (WM). We developed an allele-specific polymerase chain reaction (PCR) for this mutation, and analyzed bone marrow or peripheral blood samples from 58 patients with WM, 77 with IgM monoclonal gammopathy of undetermined significance (IgM-MGUS), 84 with splenic marginal zone lymphoma (SMZL), and 52 with B-cell chronic lymphoproliferative disorders (B-CLPD). MYD88 (L265P) was detected in 58/58 (100%) patients with WM, 36/77 (47%) with IgM-MGUS, 5/84 (6%) with SMZL, and 3/52 (4%) with B-CLPD. Compared to IgM-MGUS patients with wild-type MYD88, those carrying MYD88 (L265P) showed significantly higher levels of IgM (P < .0001) and presented Bence-Jones proteinuria more frequently at diagnosis (P = .002). During follow-up, 9 patients with IgM-MGUS progressed to WM or to marginal zone lymphoma. Using a case-control approach, the risk of evolution of patients carrying MYD88 (L265P) was significantly higher than that of patients with wild-type MYD88 (odds ratio 4.7, 95% confidence interval 0.8 to 48.7, P = .047). These findings indicate that the allele-specific PCR we developed is a useful diagnostic tool for patients with WM or IgM-MGUS. In this latter condition, MYD88 (L265P) is associated with greater disease burden and higher risk of disease progression, and the mutation may therefore also represent a useful prognostic marker.

Xu L, Hunter ZR, Yang G, et al.
MYD88 L265P in Waldenström macroglobulinemia, immunoglobulin M monoclonal gammopathy, and other B-cell lymphoproliferative disorders using conventional and quantitative allele-specific polymerase chain reaction.
Blood. 2013; 121(11):2051-8 [PubMed] Free Access to Full Article Related Publications
By whole-genome and/or Sanger sequencing, we recently identified a somatic mutation (MYD88 L265P) that stimulates nuclear factor κB activity and is present in >90% of Waldenström macroglobulinemia (WM) patients. MYD88 L265P was absent in 90% of immunoglobulin M (IgM) monoclonal gammopathy of undetermined significance (MGUS) patients. We therefore developed conventional and real-time allele-specific polymerase chain reaction (AS-PCR) assays for more sensitive detection and quantification of MYD88 L265P. Using either assay, MYD88 L265P was detected in 97 of 104 (93%) WM and 13 of 24 (54%) IgM MGUS patients and was either absent or rarely expressed in samples from splenic marginal zone lymphoma (2/20; 10%), CLL (1/26; 4%), multiple myeloma (including IgM cases, 0/14), and immunoglobulin G MGUS (0/9) patients as well as healthy donors (0/40; P < 1.5 × 10(-5) for WM vs other cohorts). Real-time AS-PCR identified IgM MGUS patients progressing to WM and showed a high rate of concordance between MYD88 L265P ΔCT and BM disease involvement (r = 0.89, P = .008) in WM patients undergoing treatment. These studies identify MYD88 L265P as a widely present mutation in WM and IgM MGUS patients using highly sensitive and specific AS-PCR assays with potential use in diagnostic discrimination and/or response assessment. The finding of this mutation in many IgM MGUS patients suggests that MYD88 L265P may be an early oncogenic event in WM pathogenesis.

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