MYD88 L265P somatic mutation: its usefulness in the differential diagnosis of bone marrow involvement by B-cell lymphoproliferative disorders

PlentiPlex™ MYD88 Waldenström lymphoma qPCR assay: A highly sensitive method for detection of MYD88 L265P mutation

INTRODUCTION

Agarose gel-based conventional and real-time allele-specific polymerase chain reaction (AS-PCR) assays are currently used for sensitive detection and quantification of MYD88 L265P mutation. Visual inspection of an agarose gel can often be ambiguous. We propose a new allele-specific quantification PCR (AS-qPCR) assay, PlentiPlex™ MYD88 Waldenström lymphoma qPCR assay, that uses Intercalating Nucleic Acid (INA®) technology for increased affinity and specificity.

METHODS

This study compares PlentiPlex™ MYD88 Waldenström lymphoma qPCR assay with conventional AS-PCR. We included a total of 102 peripheral and bone marrow blood samples from 94 patients with a lymphoproliferative disorder. Droplet digital PCR (ddPCR) was used as a third method in case of discrepancy.

RESULTS

A positive percent agreement of 100% (95% CI 0.92-1.0) and a negative percent agreement of 98% (95% CI 0.90-1.0) were found between the conventional AS-PCR and the AS-qPCR methods. Including the ddPCR results to validate the discrepant cases, the sensitivity and specificity of PlentiPlex™ MYD88 Waldenström lymphoma qPCR Assay were 1.0 (95% CI 0.97-1.0) and 1.0 (95% CI 0.96-1.0), respectively.

CONCLUSION

Our data demonstrate that PlentiPlex™ MYD88 Waldenström lymphoma qPCR assay is a fast, highly sensitive, and specific method for the detection of MYD88 L265P compared with conventional AS-PCR.

Design, synthesis, evaluation and optimization of potent IRAK4 inhibitors alleviating production of inflammatory cytokines in LPS-induced SIRS model

Interleukin-1 receptor associated kinase-4 (IRAK4) has emerged as a therapeutic target for inflammatory and autoimmune diseases. Through reversing the amide of CA-4948 and computer aided structure-activity relationship (SAR) studies, a series of IRAK4 inhibitors with oxazolo[4,5-b]pyridine scaffold were identified. Compound 32 showed improved potency (IC₅₀ = 43 nM) compared to CA-4948 (IC₅₀ = 115 nM), but suffered from hERG inhibition (IC₅₀ = 5.7 μM). Further optimization led to compound 42 with reduced inhibition of hERG (IC₅₀ > 30 μM) and 13-fold higher activity (IC₅₀ = 8.9 nM) than CA-4948. Importantly, compound 42 had favorable in vitro ADME and in vivo pharmacokinetic properties. Furthermore, compound 42 significantly reduced LPS-induced production of serum TNF-α and IL-6 cytokines in the mouse model. The overall profiles of compound 42 support it as a lead for the development of IRAK4 inhibitors for the treatment of inflammatory and autoimmune disorders.

MYD88 Mutations: Transforming the Landscape of IgM Monoclonal Gammopathies

The MYD88 gene has a physiological role in the innate immune system. Somatic mutations in MYD88, including the most common L265P, have been associated with the development of certain types of lymphoma. MYD88L265P is present in more than 90% of patients with Waldenström's macroglobulinemia (WM) and IgM monoclonal gammopathy of undetermined significance (IgM-MGUS). The absence of MYD88 mutations in WM patients has been associated with a higher risk of transformation into aggressive lymphoma, resistance to certain therapies (BTK inhibitors), and shorter overall survival. The MyD88 signaling pathway has also been used as a target for specific therapies. In this review, we summarize the clinical applications of MYD88 testing in the diagnosis, prognosis, follow-up, and treatment of patients. Although MYD88L265P is not specific to WM, few tumors present a single causative mutation in a recurrent position. The role of the oncogene in the pathogenesis of WM is still unclear, especially considering that the mutation can be found in normal B cells of patients, as recently reported. This may have important implications for early lymphoma detection in healthy elderly individuals and for the treatment response assessment based on a MYD88L265P analysis.

Nucleic Acid Biomarkers in Waldenström Macroglobulinemia and IgM-MGUS: Current Insights and Clinical Relevance

Waldenström Macroglobulinemia (WM) is an indolent lymphoplasmacytic lymphoma, characterized by the production of excess immunoglobulin M monoclonal protein. WM belongs to the spectrum of IgM gammopathies, ranging from asymptomatic IgM monoclonal gammopathy of undetermined significance (IgM-MGUS), through IgM-related disorders and asymptomatic WM to symptomatic WM. In recent years, its complex genomic and transcriptomic landscape has been extensively explored, hereby elucidating the biological mechanisms underlying disease onset, progression and therapy response. An increasing number of mutations, cytogenetic abnormalities, and molecular signatures have been described that have diagnostic, phenotype defining or prognostic implications. Moreover, cell-free nucleic acid biomarkers are increasingly being investigated, benefiting the patient in a minimally invasive way. This review aims to provide an extensive overview of molecular biomarkers in WM and IgM-MGUS, considering current shortcomings, as well as potential future applications in a precision medicine approach.

Myeloid Nuclear Differentiation Antigen (MNDA): an aid in differentiating lymphoplasmayctic lymphoma and splenic marginal zone lymphoma in bone marrow biopsies at presentation

The differential diagnosis between lymphoplasmacytic lymphoma (LPL) and marginal zone B-cell lymphoma, particularly splenic type (SMZL) can be challenging on onset bone marrow biopsy (BMB) since morphology and phenotype are not specific and clinical features can overlap or be mildly developed at diagnosis. The LPL-specific L265P mutation in the MYD88 gene is not available in all laboratories and genetic aberrancies identified in SMZL (del7q, mutations of NOTCH2 and KLF2) are seldom searched in routine practice. The study aim is to investigate the potential role of MNDA expression in this specific differential diagnosis. We report MNDA reactivity in 559 small B-cell lymphoma (SBCL) patients including bone marrow biopsies from 90 LPL and 91 SMZL. MYD88 p.Leu265Pro mutation status was assessed and confirmed as positive in 24 of 90 LPL cases, which served as the test set. MNDA staining was negative in 23/24 LPL cases in the test set (96%). In the 157 remaining cases (66 LPL, 91 SMZL), which served as validation set, the MYD88 p.Leu265Pro mutation was unavailable and MNDA was more frequently expressed in SMZL (p<0.00001). In addition, immunohistochemical features more consistent with SMZL (i.e. presence of CD23+ follicular dendritic cell meshworks, polytypic plasma cells, DBA44 reactivity) were more often present in MNDA positive cases (statistically significant for 2 such parameters). On the widest case-series so far published focusing on LPL and SMZL immunohistochemical diagnosis at onset on BMB, we demonstrated that MNDA expression significantly support the diagnosis of SMZL. This observation may be of particular help in cases where the MYD88 p.Leu265Pro mutational status and/or SMZL-related genetic aberrations are unavailable.

IgM Plasma Cell Myeloma

OBJECTIVES

Immunoglobulin M plasma cell myeloma (IgMPCM) is a rare entity that is difficult to distinguish from other IgM-related neoplasms. The study aims to characterize the clinicopathologic features of IgMPCM, including MYD88 L265P and CXCR4 mutations.

METHODS

From our institutional archives, bone marrow biopsy specimens from January 1, 2008, to December 1, 2018, with monotypic plasma cells (PCs) expressing IgM that met current International Myeloma Working Group/World Health Organization criteria for PCM were included. Sanger sequencing was used to test for MYD88 L265P and WHIM-like CXCR4 mutations.

RESULTS

Nine cases of IgMPCM were identified. Serum IgM paraproteins were detected in eight cases. CD138-positive PC burden averaged 41.9% (5%-80%). In four cases, PCs had lymphoplasmacytic morphology with cyclin D1 expression by immunohistochemistry. Three of four tested cases were positive for t(11;14) by fluorescence in situ hybridization, one with monosomy 13. The remaining case was positive for del13q14. All were negative for MYD88 L265P and WHIM-like CXCR4 mutations. Eight patients received immunochemotherapy, with four receiving autologous hematopoietic stem cell transplant. Median follow-up was 61 months (range, 11-120). All patients were alive except one.

CONCLUSIONS

Distinguishing IgMPCM from other IgM-related disorders requires correlation with clinical, laboratory, and radiologic findings. Exclusion of MYD88 L265P and WHIM-like CXCR4 mutations may be useful to diagnose IgMPCM.

Assessment of fixed-duration therapies for treatment-naïve Waldenström macroglobulinemia

Comparative data guiding initial therapy for Waldenström macroglobulinemia (WM), an infrequently encountered non-Hodgkin lymphoma, are sparse. We evaluated three commonly used rituximab-based frontline regimens: rituximab-bendamustine (R-Benda); dexamethasone, rituximab, cyclophosphamide (DRC); and bortezomib, dexamethasone, rituximab (BDR) in 220 treatment-naïve patients with WM, seen at Mayo Clinic between November 1, 2000 and October 31, 2019. The median follow-up was 4.5 (95%CI: 4-5) years. The R-Benda cohort (n = 83) demonstrated superior overall response rate (ORR: 98%), in comparison to DRC (n = 92, ORR: 78%) or BDR (n = 45, ORR: 84%) cohorts, p = 0.003. Similarly, longer progression-free survival (PFS) was evident with R-Benda use [median 5.2 vs. 4.3 (DRC) and 1.8 years (BDR), p < 0.001]. The time-to-next therapy (TTNT) favored R-Benda [median, not-reached, 4.4 (DRC) and 2.6 years (BDR), p < 0.001). These endpoints were comparable between the DRC and BDR cohorts. Overall survival (OS) was similar across the three cohorts, p = 0.77. In a subset analysis of 142 patients genotyped for MYD88^L265P mutation, the ORR, PFS and TTNT were unaffected by the patients' MYD88 signature within each cohort. In conclusion, ORR, PFS and TTNT with R-Benda are superior compared to DRC or BDR in treatment-naïve patients with active WM. The patient outcomes with any one of these three regimens are unaffected by the MYD88^L265P mutation status.

Frequency of MYD88 L256P mutation and its correlation with clinico-hematological profile in mature B-cell neoplasm

OBJECTIVE/BACKGROUND

B-cell neoplasms are clonal tumors of B cells at various stages of maturation, including diffuse large B-cell lymphoma (DLBCL), chronic lymphocytic lymphoma (CLL), Burkitt lymphoma (BL), lymphoplasmacytic lymphoma (LPL)/Waldenström's macroglobulinemia (WM), splenic marginal zone lymphoma (SMZL), nodal marginal zone lymphoma (NMZL), mantle cell lymphoma (MCL), follicular lymphoma (FL), and hairy cell leukemia (HCL). In this study, we analyzed the frequency of MYD88 L265P mutation and its correlation with clinico-hematological profile in mature B-cell neoplasms.

METHODS

A total of 110 consecutive cases of B-cell neoplasms showing peripheral blood and/or bone marrow infiltration were included. MYD88 L265P mutation was detected by polymerase chain reaction amplification of exon 5 of MYD88 gene, followed by restriction fragment length polymorphism analysis.

RESULTS

Among the 110 cases, the major group was of CLL (54.5%, n = 60), followed by HCL. Other cases included MCL, LPL, DLBCL, SMZL, NMZL, FL, and BL. MYD88 L265P mutation was seen in 21 (19.1%) cases of B-cell neoplasm, whereas 89 (80.9%) cases were negative for MYD88 L265P mutation. It was most commonly seen in LPL/WM cases followed by HCL, SMZL, CLL, and MCL cases. No case of DLBCL, FL, and BL showed MYD88 L265P mutation. Statistically significant difference was seen for hemoglobin level in CLL cases, with MYD88 L265P mutated cases showing higher mean hemoglobin levels than MYD88 wild-type cases (p = .001). For other parameters, no statistically significant difference was noted between mutated and unmutated cases.

CONCLUSION

MYD88 L265P mutation is seen in various B-cell neoplasms; it is most commonly seen in LPL/WM cases but not specific for it.

Immunoglobulin M Paraproteinaemias

Monoclonal paraproteinaemia is an increasingly common reason for referral to haematology services. Paraproteinaemias may be associated with life-threatening haematologic malignancies but can also be an incidental finding requiring only observation. Immunoglobulin M (IgM) paraproteinaemias comprise 15–20% of monoclonal proteins but pose unique clinical challenges. IgM paraproteins are more commonly associated with lymphoplasmacytic lymphoma than multiple myeloma and can occur in a variety of other mature B-cell neoplasms. The large molecular weight of the IgM multimer leads to a spectrum of clinical manifestations more commonly seen with IgM paraproteins than others. The differential diagnosis of B-cell and plasma cell dyscrasias associated with IgM gammopathies can be challenging. Although the discovery of MYD88 L265P and other mutations has shed light on the molecular biology of IgM paraproteinaemias, clinical and histopathologic findings still play a vital role in the diagnostic process. IgM secreting clones are also associated with a number of “monoclonal gammopathy of clinical significance” entities. These disorders pose a novel challenge from both a diagnostic and therapeutic perspective. In this review we provide a clinical overview of IgM paraproteinaemias while discussing the key advances which may affect how we manage these patients in the future.

Subtype Distribution, Clinical Features, and Survival in B-cell Chronic Lymphoproliferative Disorders in China: A Review of 1592 Cases

BACKGROUND

B-cell chronic lymphoproliferative disorders (B-CLPDs) are characterized by the sustained accumulation of monoclonal B cells. Limited studies have systematically described the clinical features and outcomes of the whole patient group, especially in Eastern populations.

PATIENTS AND METHODS

A total of 1592 patients with newly diagnosed B-CLPD were enrolled. Chronic lymphocytic leukemia (CLL) accounted for 39%, and Waldenström macroglobulinemia (WM), leukemic marginal zone lymphoma, follicular lymphoma (FL), and mantle cell lymphoma (MCL) constituted 13%, 13%, 9%, and 8% of cases, respectively.

RESULTS

The median age at diagnosis was 58 years, and the male/female ratio was 1.8:1. The 17p and 11q deletions were most common in MCL (36% and 17%, respectively), and 13q deletion and trisomy 12 were most frequent in CLL (35% and 21%, respectively). Patients with leukemic MCL had significantly worse survival than that of patients with other disease entities, with a 3-year overall survival (OS) of 58%, followed by 68.2% for WM/lymphoplasmacytic lymphoma. Those with CLL, leukemic marginal zone lymphoma, and FL had relatively favorable outcomes, with a 5-year OS > 80%. The survival of patients with B-CLPDs has improved over time with the emergence of novel drugs (3-year OS improvement from 82.1% to 92.2%). The improvement in survival mainly resulted from improvement among patients with MCL, WM/lymphoplasmacytic lymphoma, and FL. On multivariate analysis, only hemoglobin, lactate dehydrogenase, and 17p deletion were independently associated with survival (hazard ratio, 1.6, 2.0, and 3.1, respectively).

CONCLUSIONS

Comprehensive analysis of the clinical characteristics, immunophenotypic profiles, and cytogenetic features can be helpful in the differential diagnosis, especially for patients without a non-bone marrow biopsy specimen available. Universal prognostic factors could help with the early detection of high-risk patients and stratification for risk-adapted therapy.

Molecular characterization of sorted malignant B cells from patients clinically identified with mantle cell lymphoma

Mantle cell lymphoma (MCL) is a tumor with a poor prognosis. A few studies have examined the molecular landscape by next-generation sequencing and provided valuable insights into recurrent lesions driving this heterogeneous cancer. However, none has attempted to cross-link the individual genomic and transcriptomic profiles in sorted MCL cells to perform individual molecular characterizations of the lymphomas. Such approaches are relevant as MCL is heterogenous by nature, and thorough molecular diagnostics may potentially benefit the patient with more focused treatment options. In the work described here, we used sorted lymphoma cells from four patients at diagnosis and relapse by intersecting the coding DNA and mRNA. Even though only a few patients were included, this method enabled us to pinpoint a specific set of expressed somatic mutations, to present an overall expression profile different from the normal B cell counterparts, and to track molecular aberrations from diagnosis to relapse. Changes in single-nucleotide coding variants, subtle clonal changes in large-copy-number alterations, subclonal involvement, and changes in expression levels in the clinical course provided detailed information on each of the individual malignancies. In addition to mutations in known genes (e.g., TP53, CCND1, NOTCH1, ATM), we identified others, not linked to MCL, such as a nonsense mutation in SPEN and an MYD88 missense mutation in one patient, which along with copy number alterations exhibited a molecular resemblance to splenic marginal zone lymphoma. The detailed exonic and transcriptomic portraits of the individual MCL patients obtained by the methodology presented here could help in diagnostics, surveillance, and potentially more precise usage of therapeutic drugs by efficient screening of biomarkers.

Diagnostic value of bone marrow core biopsy patterns in lymphoplasmacytic lymphoma/Waldenström macroglobulinaemia and description of its mutational profiles by targeted NGS

AIMS

The aim of this study was to describe the characteristics of the bone marrow infiltration found in a series of clinically defined lymphoplasmacytic lymphoma (LPL)/Waldenström macroglobulinaemia (WM) and IgM-monoclonal gammopathy of undetermined significance (MGUS) and to perform a targeted next-generation sequencing (NGS) for the identification of additional somatic mutations to MYD88p.L265P in LPL/WM.

METHODS

We have reviewed a series of 35 bone marrow biopsies from 28 patients with a clinical diagnosis of LPL/WM (24 cases) or MGUS (4 cases). Bone marrow infiltration characteristics by morphology, immunohistochemistry, flow cytometry (FCM), allele-specific real-time PCR for the detection of MYD88p.L265P mutation, targeted exonic amplicon-based NGS of 35 lymphoma-related genes and direct sequencing were analysed.

RESULTS

Our findings show that bone marrow trephine biopsy evaluation is superior to FCM in the identification of significant lymphoid infiltrates. A combined paratrabecular and interstitial infiltration pattern is the most common feature in LPL/WM while a patchy interstitial pattern characterises IgM-MGUS cases. MYD88p.L265P mutation was found by allele-specific-PCR in 92% of the LPL cases (22 out of 24) and 25% of IgM-MGUS cases (1 out of 4 cases). In addition to MYD88p.L265P somatic mutations in CXCR4, KMT2D, PRDM1/Blimp1, MYC and ID3 were found by NGS and direct sequencing in 4 cases.

CONCLUSIONS

In conclusion, bone marrow core biopsy evaluation is critical in the identification of unequivocal bone marrow infiltration by LPL/WM. In addition to MYD88p.L265P, somatic mutations in CXCR4, KMT2D, PRDM1/Blimp1, MYC and ID3 can appear in a fraction of LPL/WM.

MYD88 in the driver's seat of B-cell lymphomagenesis: from molecular mechanisms to clinical implications

More than 50 subtypes of B-cell non-Hodgkin lymphoma (B-NHL) are recognized in the most recent World Health Organization classification of 2016. The current treatment paradigm, however, is largely based on 'one-size-fits-all' immune-chemotherapy. Unfortunately, this therapeutic strategy is inadequate for a significant number of patients. As such, there is an indisputable need for novel, preferably targeted, therapies based on a biologically driven classification and risk stratification. Sequencing studies identified mutations in the MYD88 gene as an important oncogenic driver in B-cell lymphomas. MYD88 mutations constitutively activate NF-κB and its associated signaling pathways, thereby promoting B-cell proliferation and survival. High frequencies of the hotspot MYD88(L265P) mutation are observed in extranodal diffuse large B-cell lymphoma and Waldenström macroglobulinemia, thereby demonstrating this mutation's potential as a disease marker. In addition, the presence of mutant MYD88 predicts survival outcome in B-NHL subtypes and it provides a therapeutic target. Early clinical trials targeting MYD88 have shown encouraging results in relapsed/refractory B-NHL. Patients with these disorders can benefit from analysis for the MYD88 hotspot mutation in liquid biopsies, as a minimally invasive method to demonstrate treatment response or resistance. Given these clear clinical implications and the crucial role of MYD88 in lymphomagenesis, we expect that analysis of this gene will increasingly be used in routine clinical practice, not only as a diagnostic classifier, but also as a prognostic and therapeutic biomarker directing precision medicine. This review focuses on the pivotal mechanistic role of mutated MYD88 and its clinical implications in B-NHL.

MYD88 L265P mutation analysis is a useful diagnostic adjunct for lymphoplasmacytic lymphoma with pleural effusion

Lymphoplasmacytic lymphoma (LPL) is a marrow-based lymphoma, rarely involving extramedullary sites, particularly the pleural cavities. The distinction of lymphomatous pleural effusion (PE) in LPL patients from benign effusion is challenging. We conducted this study to examine whether MYD88 L265P mutation analysis is useful in distinguishing benign from lymphomatous PE in four patients with LPL, in which the initial marrow specimens were all positive for MYD88 mutation. In one case each with plasma cell- or lymphocyte-predominant PE, MYD88 mutation was positive, confirming lymphomatous effusion. The other lymphocyte-predominant PE was negative for MYD88 mutation, but was clonally related to a previous nodal biopsy and this PE was also considered to have LPL involvement. The fourth case developed large B-cell lymphoma in the PE 30 months later. The PE specimen was negative for MYD88 mutation but was clonally related to the diagnostic marrow tissue, indicating large cell transformation. Four cases of small lymphocyte-predominant benign PE from patients without history of lymphoma were examined and were all negative for MYD88 L265P mutation. In conclusion, in this small case series we showed that MYD88 L265P mutation analysis could serve as a useful adjunct in distinguishing benign from lymphomatous PE in patients with LPL.

Follicular Lymphoma Presenting With Monoclonal IgM And MYD88 Mutation: A Case Report And Review Of The Literature

MYD88 mutation has been reported in various lymphomas, specifically in lymphoplasmacytic lymphoma. Yet, the mutation has not been reported in primary follicular lymphoma. Here, we present a 62-year-old male with follicular lymphoma who had an MYD88 L265P somatic mutation and monoclonal IgM gammopathy. He received four cycles of R-CHOP immunochemotherapy. Interim PET/CT evaluation indicated a state of stable disease (SD). Neither did serum IgM remarkably drop. He was then given a bortezomib-contained regimen which significantly reduced the level of serum IgM. To the best of our knowledge, this is the first report of follicular lymphoma with monoclonal IgM and MYD88 L265P mutation. The present case indicated bortezomib may benefit these patients.

IRTA1 and MNDA Expression in Marginal Zone Lymphoma: Utility in Differential Diagnosis and Implications for Classification

Objectives

To evaluate the clinical utility of immune receptor translocation-associated protein 1 (IRTA1) and myeloid nuclear differentiation antigen (MNDA) expression in the diagnosis and classification of marginal zone lymphomas (MZLs).

Methods

IRTA1 was examined using a novel RNA in situ hybridization assay and MNDA expression determined by immunohistochemistry in 127 small B-cell neoplasms, including 80 cases of MZL.

Results

IRTA1 expression was detected in 31 (42%) of 74 MZLs vs one (2%) of 43 other small B-cell neoplasms (P < .001). MNDA staining was positive in 51 (64%) of 79 MZLs vs 21 (45%) of 46 non-MZLs (P = .06). MNDA expression was particularly uncommon in follicular lymphoma (3/14, 21%; P = .003 vs MZL). There was no association between MNDA and IRTA1 expression and the presence of monocytoid cytology. IRTA1 expression was less frequent in cases with a diffuse growth pattern.

Conclusions

IRTA1 and MNDA are useful markers in the differential diagnosis of MZLs.

MYD88 and CXCR4 Mutation Profiling in Lymphoplasmacytic Lymphoma/Waldenstrom's Macroglobulinaemia

Recurrent mutations affecting MYD88 and CXCR4 gene nowadays form the basis for the diagnosis, risk stratification and use of inhibitors targeting these signalling pathways in LPL/WM which are rare B cell neoplasms. MYD88 L265P mutation analysis was performed on 33 cases of LPL/WM by AS-PCR (positivity-84.8%, n = 28/33) and by Sanger sequencing (positivity-39.3%, n = 13/33). We had only two cases with CXCR4 non-sense (NS) mutation (p.S338*) using Sanger sequencing. MYD88 (L265P) mutation detection by AS-PCR can form reliable biomarker for the diagnosis of LPL/WM in molecular labs. Although the cohort is small, still the CXCR4 mutation frequency in our study is low as compared to the published literature.

High Frequency of MYD88 L265P Mutation in Primary Ocular Adnexal Marginal Zone Lymphoma and Its Clinicopathologic Correlation: A Study From a Single Institution

CONTEXT.—

The pathogenesis of primary ocular adnexal marginal zone lymphoma (POAMZL) remains unclear. The reported associations with Chlamydia psittaci infection and MYD88 mutations are highly variable.

OBJECTIVE.—

To examine MYD88 L265P mutation in ocular marginal zone lymphomas and correlate with clinicopathologic features and Chlamydia infection.

DESIGN.—

Presence of MYD88 L265P mutation and Chlamydia infection in lymphoma was analyzed by using sensitive polymerase chain reaction (PCR) methods.

RESULTS.—

The MYD88 L265P mutation was identified in 8 of 22 POAMZLs (36%), including 2 of 3 cases in which PCR failed to detect clonal IGH gene rearrangement; none of the 4 secondary marginal zone lymphomas were positive. Test results for Chlamydia were negative in all cases. Patients with and without the MYD88 mutation had similar clinicopathologic features.

CONCLUSIONS.—

The MYD88 mutational analysis provides important information in diagnostic workup of POAMZL. The frequent MYD88 mutation suggests a critical role of this aberration in the pathogenesis of POAMZL and may serve as a therapeutic target for patients with progressive disease.

MYD88 mutation status does not impact overall survival in Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is an immunoglobulin M-associated lymphoma, with majority of cases demonstrating MYD88 locus alteration, most commonly, MYD88^L265P . Owing to low prevalence of the wild-type (WT) MYD88 genotype in WM, clinically relevant data in this patient population are sparse, with one study showing nearly a 10-fold increased risk of mortality in this subgroup compared to patients with MYD88^L265P mutation. We studied a large cohort of patients with MYD88^L265P and MYD88^WT WM, evaluated at Mayo Clinic, Rochester, between 1995 and 2016, to specifically assess the impact of these genotypes on clinical course. Of 557 patients, MYD88^L265P mutation status, as determined by allele-specific polymerase chain reaction, was known in 219, and 174 (79%) of those exhibited MYD88^L265P , 157 of 174 patients had active disease. Of 45 (21%) patients with MYD88^WT genotype, 44 had active disease. The estimated median follow-up was 7.0 years; median overall survival was 10.2 years (95% CI: 8.4-16.5) for MYD88^L265P versus 13.9 years (95% CI: 6.4-29.3) for the MYD88^WT (P = 0.86). The time-to-next therapy from frontline treatment and the presenting features were similar in the two patient populations. For patients with smoldering WM at diagnosis, the median time-to-progression to active disease was 2.8 years (95% CI: 2.2-3.8) in the MYD88^L265P cohort and 1.9 years (95% CI: 0.7-3.1) in the MYD88^WT cohort (P = 0.21). The frequency of transformation to high-grade lymphoma, or the development of therapy-elated myelodysplastic syndrome was higher in the MYD88^WT cohort (16% versus 4% in the MYD88^L265P , P = 0.009). In conclusion, MYD88^L265P mutation does not appear to be a determinant of outcome, and its presence may not be a disease-defining feature in WM. Our findings warrant external validation, preferably through prospective studies.

Lack of Associations between TLR9 and MYD88 Gene Polymorphisms and Risk of Chronic Lymphocytic Leukemia

Background:

Genetic factors like single nucleotide polymorphisms (SNPs) may play an important role in the etiology of chronic lymphocytic leukemia (CLL). Mutations in Toll like receptor 9 (TLR9) and myeloid differentiation primary response 88 (MYD88) genes may lead to an abnormal immune response that may cause greater cell proliferation and thus alter an individual’s susceptibility to haematological malignancies including CLL.

Objective:

This work was designed to study any association of the TLR9 (rs2066807C/G and rs187084T/C) and MYD88 (L265P) single nucleotide polymorphism (SNPs) with risk of CLL in Egyptians.

Materials and methods:

One hundred patients with CLL and 100 healthy controls from the Egyptian population were genotyped by the polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) method.

Results:

With TLR9 rs2066807C/G the CC genotype was more frequent in both control and patient groups while for TLR9 rs187084T/C the TT genotype was most common. There were no significant associations with CLL risk. With MYD88 (L265P) only the TT genotype was detected.

Conclusion:

Our preliminary data suggest that polymorphisms in the TLR9 and MYD88 genes may not contribute to CLL susceptibility. To the best of our knowledge, this study is the first dealing with TLR9 and MYD88 gene polymorphisms in CLL patients. Further studies with larger sample size should be conducted to validate these results in the Egyptian population.

Clone-specific MYD88 L265P and CXCR4 mutation status can provide clinical utility in suspected Waldenström macroglobulinemia/lymphoplasmacytic lymphoma

MYD88 L265P, a diagnostic marker for lymphoplasmacytic lymphoma (LPL)/Waldenström macroglobulinemia (WM) can also be detected in other hematopoietic malignancies. We demonstrate a novel approach to increase the specificity of this marker for WM/LPL diagnosis by combining flow cytometric cell sorting with molecular analysis. Clonal B-lymphocyte and co-occurring clonal plasma cell populations of low-grade B-cell lymphomas were sorted by flow cytometry and analyzed for immunoglobulin gene rearrangements (PCR), and for MYD88 and CXCR4 mutations. Identical clonal origin was confirmed by PCR for 21 LPL/WM cases and MYD88 L265P was detected in both B-cell and plasma cell fractions. 9/20 other B-cell lymphomas with identical light chain restriction on B-cells and plasma cells were genotypically identical by PCR and MYD88 L265P was detected in both cell fractions in 7/9 whereas in 11/20 specimens with different clonal origin, MYD88 L265P was absent (5/11), or only found in B-lymphocytes (4/11), or plasma cells (2/11). CXCR4 mutations were detected in 17/39 cases, but missed in 63% of these without cell sorting. Confirming MYD88L265P in both B-cells and plasma cell fractions can provide a novel and powerful discriminator to distinguish LPL/WM from phenotypically similar disorders. Furthermore, this approach significantly increases CXCR4 detection sensitivity.

Detection of MYD88 L265P in patients with lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia and other B-cell non-Hodgkin lymphomas

Background

Recent studies have identified a high prevalence of the MYD88 L265P mutation in lymphoplasmacytic lymphoma (LPL)/Waldenstrom macroglobulinemia (WM) cases, whereas low frequencies have been observed in other B cell non-Hodgkin lymphomas (NHLs).

Methods

We evaluated the sensitivity of the mutant enrichment 3'-modified oligonucleotide (MEMO)-PCR technique, a new detection method. We examined the MYD88 L265P mutation in a series of Korean patients with LPL/WM and other B cell NHLs in bone marrow aspirates, using the MEMO-PCR technique.

Results

The sensitivity of MEMO-PCR was estimated to be approximately 10-16.7%. MYD88 L265P was detected in 21 of 28 LPL cases (75%) and only three of 69 B cell NHL cases (4.3%).

Conclusion

Although MEMO-PCR had relatively low sensitivity, we confirmed the high prevalence of the MYD88 L265P mutation in Korean LPL patients. Our study suggests the diagnostic value of MYD88 L265P for differentiating B-cell NHLs.

Lymphoplasmacytic Lymphoma With a Non-IgM Paraprotein Shows Clinical and Pathologic Heterogeneity and May Harbor MYD88 L265P Mutations

OBJECTIVES

Lymphoplasmacytic lymphoma (LPL) with non-immunoglobulin M (IgM) paraproteinemia remains poorly understood. The goal of this study was to investigate the clinicopathologic features of LPL in the bone marrow in patients with immunoglobulin G (IgG) or immunoglobulin A (IgA) paraproteins and evaluate MYD88 L265P mutation status to determine the relationship of these cases to Waldenström macroglobulinemia (WM).

METHODS

Bone marrows from LPL cases with IgG or IgA paraproteins diagnosed between January 1, 2007, and June 30, 2014, were retrieved from the clinical archive. Clinicopathologic features were retrospectively reviewed. MYD88 L265P mutation status was assessed by allele-specific polymerase chain reaction prospectively on all cases.

RESULTS

Of 27 cases, four were reclassified as multiple myeloma, all MYD88 mutation negative. MYD88 L265P mutations were present in 10 (43%) of 23 remaining cases. No association between MYD88 status and bone marrow morphologic or phenotypic features, including the presence of Dutcher bodies, mast cells, expression of CD19 by plasma cells, or hemosiderin, was identified, although these features were present in a subset of cases, similar to WM. Clinical features of WM such as hyperviscosity were uncommon in this group and did not correlate with MYD88 status.

CONCLUSIONS

Non-IgM LPLs are a clinically and pathologically heterogeneous group and often harbor MYD88 L265P mutation, albeit at a lower rate than classic WM. MYD88 status does not correlate with any specific pathologic or clinical manifestations.

Genetic aberrations in small B-cell lymphomas and leukemias: molecular pathology, clinical relevance and therapeutic targets

Small B-cell lymphomas and leukemias (SBCLs) are a clinically, morphologically, immunophenotypically and genetically heterogeneous group of clonal lymphoid neoplasms, including entities such as chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), mantle cell lymphoma (MCL), follicular lymphoma (FL), lymphoplasmacytic lymphoma (LPL), marginal zone lymphoma (MZL) and hairy cell leukemia (HCL). The pathogenesis of some of these lymphoid malignancies is characterized by distinct translocations, for example t(11;14) in the majority of cases of MCL and t(14;18) in most cases of FL, whereas other entities are associated with a variety of recurrent but nonspecific numeric chromosomal abnormalities, as exemplified by del(13q14), del(11q22), and +12 in CLL, and yet others such as LPL and HCL that lack recurrent or specific cytogenetic aberrations. The recent surge in next generation sequencing (NGS) technology has shed more light on the genetic landscape of SBCLs through characterization of numerous driver mutations including SF3B1 and NOTCH1 in CLL, ATM and CCND1 in MCL, KMT2D and EPHA7 in FL, MYD88 (L265P) in LPL, KLF2 and NOTCH2 in splenic MZL (SMZL) and BRAF (V600E) in HCL. The identification of distinct genetic lesions not only provides greater insight into the molecular pathogenesis of these disorders but also identifies potential valuable biomarkers for prognostic stratification, as well as specific targets for directed therapy. This review discusses the well-established and recently identified molecular lesions underlying the pathogenesis of SBCLs, highlights their clinical relevance and summarizes novel targeted therapies.

Plasma cell and terminal B-cell differentiation in mantle cell lymphoma mainly occur in the SOX11-negative subtype

Mantle cell lymphoma is a mature lymphoid neoplasm characterized by the t(11;14)(q13;q32) and cyclin D1 overexpression. SOX11 is a transcription factor commonly overexpressed in these tumors but absent in most other mature B-cell lymphomas whose function is not well understood. Experimental studies have shown that silencing of SOX11 in mantle cell lymphoma cells promotes the shift from a mature B cell into an early plasmacytic differentiation phenotype, suggesting that SOX11 may contribute to tumor development by blocking the B-cell differentiation program. The relationship between SOX11 expression and terminal B-cell differentiation in primary mantle cell lymphoma and its relationship to the plasmacytic differentiation observed in occasional cases is not known. In this study we have investigated the terminal B-cell differentiation phenotype in 60 mantle cell lymphomas, 41 SOX11-positive and 19 SOX11-negative. Monotypic plasma cells and lymphoid cells with plasmacytic differentiation expressing cyclin D1 were observed in 7 (37%) SOX11-negative but in none of 41 SOX11-positive mantle cell lymphomas (P<0.001). Intense cytoplasmic expression of a restricted immunoglobulin light chain was significantly more frequent in SOX11-negative than -positive tumors (58 vs 13%) (P=0.001). Similarly, BLIMP1 and XBP1 expression was also significantly more frequent in SOX11-negative than in -positive cases (83 vs 34% and 75 vs 11%, respectively) (P=0.001). However, no differences in the expression of IRF4/MUM1 were observed among these subtypes of mantle cell lymphoma. In conclusion, these results indicate that SOX11-negative mantle cell lymphoma may be a particular subtype of this tumor characterized by more frequent morphological and immunophenotypic terminal B-cell differentiation features that may be facilitated by the absence of SOX11 transcription factor.

Lymphoplasmacytic lymphoma and marginal zone lymphoma in the bone marrow: paratrabecular involvement as an important distinguishing feature

OBJECTIVES

The differential diagnosis between bone marrow involvement by lymphoplasmacytic lymphoma (LPL) and marginal zone lymphoma (MZL) is challenging because histology and immunophenotype of both diseases overlap. We revisited the diagnostic pathology features of both diseases in the bone marrow.

METHODS

We studied a series of bone marrow trephine biopsy specimens from 59 patients with Waldenström macroglobulinemia without extramedullary involvement and bone marrow biopsy specimens from 23 patients with well-characterized MZL who also had bone marrow involvement. H&E- and immunoperoxidase-stained sections of bone marrow trephine biopsy specimens as well as flow cytometry and classic cytogenetics performed on aspirations were reviewed. The study was complemented with MYD88 L265P mutation analysis of all samples.

RESULTS

The most distinguishing features of LPL with respect to MZL were focal paratrabecular involvement (P < .001), the presence of lymphoplasmacytoid cells (P < .001) and Dutcher bodies (P < .001), increased numbers of mast cells (P < .001), and the MYD88 L265P mutation (P < .001).

CONCLUSIONS

LPL can be reliably distinguished from MZL in the bone marrow by using a combination of pathology characteristics. Our findings stress the diagnostic importance of using the combination of the following parameters for a correct LPL diagnosis: paratrabecular infiltration, the presence of lymphoplasmacytoid cells and cells with Dutcher bodies, and an increased number of mast cells in addition to the presence of MYD88 mutation.

MYD88 L265P mutation analysis helps define nodal lymphoplasmacytic lymphoma

The diagnosis of lymphoplasmacytic lymphoma is often challenging, especially in extramedullary tissues where the differential diagnosis includes nodal marginal zone lymphoma, splenic marginal zone lymphoma, or other small B-cell neoplasms with plasmacytic differentiation. The MYD88 L265P mutation has been recently identified in >90% of bone-marrow-based lymphoplasmacytic lymphoma, but the incidence of this abnormality and corresponding morphologic correlates in nodal lymphoplasmacytic lymphoma have not been established. We analyzed 87 cases of extramedullary lymphoplasmacytic lymphoma, splenic marginal zone lymphoma, unclassifiable splenic B-cell lymphomas, nodal marginal zone lymphoma with plasmacytic differentiation, and chronic lymphocytic leukemia/small lymphocytic lymphoma with plasmacytic differentiation for MYD88 L265P. Eighteen cases (21%) were positive, including 9/9 (100%) lymphoplasmacytic lymphomas with classic histologic features, 5/12 (42%) cases that met 2008 WHO criteria for lymphoplasmacytic lymphoma but with atypical morphologic features, 3/15 (20%) cases initially considered nodal marginal zone lymphoma with plasmacytic differentiation, and 1/6 (17%) unclassifiable splenic B-cell lymphomas. The presence of MYD88 L265P was associated with IgM paraprotein (P<0.001) and a trend for bone marrow involvement (P=0.09). Each of 44 splenectomy-defined splenic marginal zone lymphomas (19 with plasmacytic differentiation) and the chronic lymphocytic leukemia/small lymphocytic lymphoma with plasmacytic differentiation were negative for the mutation. Morphologic re-review with knowledge of MYD88 mutation status and all available clinical features suggested all MYD88 mutated cases were consistent with lymphoplasmacytic lymphoma (either classic or variant histology), except for one case which remained most consistent with nodal marginal zone lymphoma with plasmacytic differentiation. These results demonstrate the importance of MYD88 mutational analysis in better defining lymphoplasmacytic lymphoma as a relatively monomorphic small B-cell lymphoma with plasmacytic differentiation that may show total nodal architectural effacement and follicular colonization. Cases previously considered lymphoplasmacytic lymphoma that are more polymorphous and are often associated with histiocytes should no longer be included in the lymphoplasmacytic lymphoma category. Clinicopathologic review suggests that although MYD88 mutated non-lymphoplasmacytic lymphoma small B-cell neoplasms exist, they are very uncommon.

Pathology of B-cell lymphomas: diagnosis and biomarker discovery

The diagnosis of B-cell non-Hodgkin lymphomas has changed significantly over the past few decades as new immunophenotypic markers, molecular subtype classification schemes, and novel biomarkers have emerged. Meanwhile, there has been an increasing emphasis on individualizing treatment approaches in accordance with a biologic heterogeneity that has been uncovered within many of the individual B-cell lymphoma entities. The application of high-throughput genomic sequencing to B-cell lymphomas has yielded large amounts of valuable information. The data encompass discoveries essential to an understanding of pathogenesis, clonal or tumoral evolution, and identification of biomarkers that may be useful for prognostic or therapeutic considerations. The following review discusses several of the more common, primarily tissuebased B-cell lymphomas, with a focus on pathologic classification and certain phenotypic characteristics or genetic lesions that apply to refinement of diagnosis and therapy.

New Immunohistochemistry for B-Cell Lymphoma and Hodgkin Lymphoma

Context

B-cell non-Hodgkin lymphoma is a heterogeneous group of lymphoproliferative malignancies with different clinical behaviors and treatments. It is important to differentiate individual B-cell lymphoma to apply the best treatment and management. Morphology and immunohistochemistry are the primary tools used for diagnosing lymphoma. There is a characteristic pattern of expression with immunohistochemical antibodies in most well-defined B-cell lymphomas. Some cases of B-cell lymphoma, however, show unusual morphologic and immunophenotypic features. The new and sometimes more specific antibodies have been developed recently, which may further define those lymphomas. Only with use of the antibodies over time does their true nature and specificity become evident.

Objectives

To present new antibodies for B-cell lymphoma that enhance the probability for diagnosis or can act as alternate markers in unusual cases, in which a B-cell lymphoma does not present with characteristic immunohistochemical staining, and to present prognostic markers that allow for better management of patients with specific B-cell lymphomas.

Data Sources

Data were obtained from literature review and figures from slides in personal practice.

Conclusions

The immunohistochemical antibodies presented in this article increase our ability to understand, diagnosis, and manage patients with B-cell lymphoma.

Clonotypic analysis of immunoglobulin heavy chain sequences in patients with Waldenström's macroglobulinemia: correlation with MYD88 L265P somatic mutation status, clinical features, and outcome

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.

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.