Waldenström macroglobulinemia: 2015 update on diagnosis, risk stratification, and management

Acute kidney injury due to direct infiltration by lymphoplasmacytic lymphoma secreting IgG paraproteins: A case report

INTRODUCTION

Waldenström's macroglobulinemia is a lymphoplasmacytic lymphoma (LPL) associated with a monoclonal immunoglobulin M protein. Although acute kidney injury (AKI) due to immunoglobulin M paraprotein infiltration into the renal interstitium has been reported, there has been no report of AKI with invasion of the immunoglobulin G paraprotein into the renal interstitium in a patient with LPL.

PATIENT CONCERNS

A 65-year-old male was admitted to our hospital with fatigue and decreased renal function. He complained of a 3-kg weight loss in the last 3 months.

DIAGNOSIS

The initial blood urea nitrogen and serum creatinine levels were 55.9 and 1.83 mg/dL, respectively. Serum protein electrophoresis revealed a monoclonal component (3.5 g/dL) in the gamma region and immunofixation electrophoresis showed an immunoglobulin G kappa monoclonal protein. Renal pathology revealed that CD3-CD20+ CD138+ lymphoid cells had infiltrated the renal interstitium. A bone marrow biopsy was compatible with LPL.

INTERVENTIONS

Intravenous methylprednisolone (1 mg/kg) was administered after confirming the renal pathological findings.

OUTCOMES

Serum creatinine decreased to 0.8 mg/dL 14 days after treatment.

CONCLUSIONS

Physicians should recognize LPL secreting various immunoglobulins as a possible cause of AKI when renal failure of unknown etiology and serum immunoglobulin paraprotein is present. A kidney biopsy should be performed for definitive diagnosis and appropriate management.

Does Waldenstrom's macroglobulinemia also cause bone destruction? A rare case report

Waldenstrom’s macroglobulinemia (WM) is a rare type of malignant B-cell lymphoma. The main feature of WM is elevated serum monoclonal immunoglobulin M, similar to multiple myeloma (MM). Unlike in MM, the rarity of destructive bone lesions in WM has been repeatedly emphasized. We report a unique case of WM with a vertebral compression fracture as the first symptom. This case highlights that the presence or absence of bone destruction may not clearly distinguish between WM and MM. The possibility of WM should be considered in patients with vertebral fracture and destruction as the first presentation. Performing vertebral bone marrow aspiration biopsy during percutaneous vertebroplasty is a convenient and effective method to assist in the diagnosis of WM.

A challenging case of lymphoproliferative disease in a cat

A 7-year-old male castrated Maine Coon cat presented with edema of the right hindlimb and a markedly enlarged right popliteal lymph node. A CBC showed a neutropenia of 1.5 × 10³ /μL. Radiographs and ultrasonographic examination were unremarkable. Cytology of the right popliteal lymph node revealed a mixed population of cells, consisting predominantly of medium to large plasmacytoid lymphocytes, low to moderate numbers of well-differentiated plasma cells and low numbers of small lymphocytes. Plasmacytoid lymphocytes had round nuclei with finely stippled chromatin and one prominent round nucleolus. Low numbers of binucleated cells and bizarre mitotic figures, and rare multinucleated cells were observed. Histopathologic examination of the lymph node showed effacement of the normal lymph node architecture by dense sheets of neoplastic cells. Round to polygonal tumor cells of intermediate size had a low to moderate amount of cytoplasm. Round to indented hyperchromatic nuclei were often eccentrically located and contained one distinct nucleolus. Anisocytosis and anisokaryosis were moderate and 21 mitoses/10 high power field (HPF) were present. Congo red staining was negative. High numbers of tumor cells were positive for lambda light chain immunoglobulin; moderate numbers stained positive for MUM-1. A clonal BCR gene rearrangement was detected with an immunoglobulin heavy chain target (IGH), immunoglobulin lambda light chain (IgL), and kappa deleting element (Kde). Differential diagnoses for the lymphoproliferative disease in this cat included lymphoplasmacytic lymphoma and myeloma-related disorder.

Screening and identification of a novel FHL2 mutation by whole exome sequencing in twins with familial Waldenström macroglobulinemia

BACKGROUND

Waldenström macroglobulinemia (WM) is a rare chronic B-cell lymphoma. Familial clustering of WM has been observed over the years. However, little is known about the contribution of inherited genetic variants to familial WM cases.

METHODS

The authors performed whole exome sequencing (WES) of germline DNA samples from twins, one diagnosed with WM and the other diagnosed with immunoglobulin M monoclonal gammopathy of undetermined significance, and their healthy siblings. Bioinformatics analysis of public biological databases was used to identify the most relevant familial WM candidate from WES. Transcript expression and protein levels of the familial WM candidate were evaluated in the WM patient and 2 unaffected members of the kindred.

RESULTS

Among the 10 shared candidate mutations in the twins, the authors identified a novel heterozygous germline mutation in four and a half LIM domains protein 2 (FHL2; c.G226A, p.V76M) as a familial WM-associated mutation. FHL2 appeared to be connected with reported signaling pathways and disease-driving genes such as IL6 and HCK in WM. In addition, the authors found reduced FHL2 messenger RNA and protein expression in peripheral blood samples from the patient with WM in comparison with the healthy siblings.

CONCLUSIONS

Taken together, these findings indicate that an FHL2^g226a mutation may play an important role in familial WM, and they provide new screening possibilities for familial cases.

LAY SUMMARY

Familial clustering in Waldenström macroglobulinemia (WM) has been observed over the years. The authors performed whole exome sequencing of germline DNA samples from twins, one diagnosed with WM and the other diagnosed with immunoglobulin M monoclonal gammopathy of undetermined significance, and their healthy siblings. Among the 10 shared candidate mutations in the twins, a novel heterozygous germline mutation in four and a half LIM domains protein 2 (FHL2; c.G226A, p.V76M) was identified as the most relevant familial WM candidate through bioinformatics analysis of a public database. Also, messenger RNA and protein expression of FHL2 was significantly lower in peripheral blood mononuclear cells of the WM patient in comparison with the healthy siblings, and this suggested that the function of FHL2 was impaired when mutated.

Clinicopathological characteristics and long-term prognosis of monoclonal immunoglobulin light chain associated Fanconi syndrome

Background and aims:

Monoclonal immunoglobulin light chain associated Fanconi syndrome (LC-FS) is a rare disease that involves proximal tubules. As most of the reported cases came from western countries, we aimed to analyze the clinicopathological characteristics of Asian LC-FS and its treatment responses to chemotherapy.

Methods:

A total of 26 LC-FS patients in a single-center were retrospectively studied.

Results:

At diagnosis, the mean age of the 26 Asian LC-FS patients was 54.7 ± 14.7 years, with females accounting for 57.7%. They presented with different degrees of proximal tubular dysfunctions with normoglycemic glycosuria (88.0%), hyperphosphaturia (84.2%) and aminoaciduria (84.0%) as the most common features. The mean estimated glomerular filtration rate (eGFR) was (68.0 ± 26.4) ml/min per 1.73 m². After chemotherapy, renal response was achieved in 58.3% cases, which was accompanied by hematological response, and tubular response was acquired in 66.7% cases. During 3 years of follow-up, the eGFR levels significantly decreased in the monoclonal gammopathy of renal significance patients, few of whom (21.4%) had received chemotherapy.

Conclusion:

Asian LC-FS patients had mild renal function disorder. The chemotherapy could improve both renal and tubular functions, which may be related to the hematological response.

Orally effective FDA-approved protein kinase targeted covalent inhibitors (TCIs)

Because dysregulation of protein kinases owing to mutations or overexpression plays causal roles in human diseases, this family of enzymes has become one of the most important drug targets of the 21st century. Of the 62 protein kinases inhibitors that are approved by the FDA, seven of them form irreversible covalent adducts with their target enzymes. The clinical success of ibrutinib, an inhibitor of Bruton tyrosine kinase, in the treatment of mantle cell lymphomas following its approval in 2013 helped to overcome a general bias against the development of irreversible drug inhibitors. The other approved covalent drugs include acalabrutinib and zanubrutinib, which also inhibit Bruton tyrosine kinase. Furthermore afatinib, dacomitinib, and osimertinib, inhibitors of members of the epidermal growth factor receptor family (ErbB1/2/3/4), are used in the treatment of non-small cell lung cancers. Neratinib is an inhibitor of ErbB2 and is used in the treatment of ErbB2/HER2-positive breast cancer. The seven drugs considered in this review have a common mechanism of action; this process involves the addition of a protein cysteine thiolate anion (protein‒S:^-) to an acrylamide derivative (CH₂=CHC(=O)N(H)R) where R represents the pharmacophore. Such reactions are commonly referred to as Michael additions and each reaction results in the formation of a covalent bond between carbon and sulfur; the final product is a thioether. This process consists of two discrete steps; the first step involves the reversible association of the drug with its target enzyme so that a weakly electrophilic functionality, a warhead, is bound near an appropriately positioned nucleophilic cysteine. In the second step, a reaction occurs between the warhead and the target enzyme cysteine to form a covalently modified and inactive protein. For this process to work, the warhead must be appropriately juxtaposed in relationship to the cysteinyl thiolate so that the covalent addition can occur. Covalent inhibitors have emerged from the ranks of drugs to be avoided to become an emerging paradigm. Much of this recent success can be attributed to the clinical efficacy of ibrutinib as well as the other antagonists covered in this review. Moreover, the covalent inhibitor methodology is swiftly gaining acceptance as a valuable component of the medicinal chemist's toolbox and is primed to make a significant impact on the development of enzyme antagonists and receptor modulators.

Optical coherence tomography angiography characteristics in Waldenström macroglobulinemia retinopathy: A case report

BACKGROUND

Waldenström macroglobulinemia (WM) is a distinct clinicopathologic entity characterized by the infiltration of the bone marrow by clonal lymphoplasmacytic cells that produce monoclonal immunoglobulin M (IgM) in the blood, and patients may present with symptoms related to the infiltration of the hematopoietic tissues or the effects of monoclonal IgM in the blood. Funduscopic abnormalities were noted in some of the patients due to hyperviscosity or other retinal lesions. Optical coherence tomography angiography (OCTA) as a non-invasive imaging tool can give qualitative and quantitative information about the status of retinal and choroidal vessels, which might be useful for diagnosing patients with WM-associated retinopathy.

CASE SUMMARY

The patient was a 67-year-old man who presented with sudden visual disturbance in both eyes. Ophthalmic tests showed that best corrected visual acuity (BCVA) for this patient was 20/100 in the right eye and 20/1000 in the left eye. Fundus examination, optical coherence tomography (OCT), and OCTA revealed substantial bilateral optic disc edema, dilated and tortuous retinal veins, and diffuse intraretinal blot hemorrhages and edema which were consistent with bilateral central retinal vein occlusion (CRVO). Meanwhile, remarkable bilateral serous macular detachments (SMD) were noticed on OCT. Systemic examinations showed that the patient had anemia and extremely high level of monoclonal IgM and infiltration of clonal lymphoplasmacytic cells in bone marrow. The diagnosis of WM with hyperviscosity and retinopathy was made based on the clinical manifestation and laboratory findings. He was subsequently treated with intravitreal ranibizumab injection, plasmapheresis, and bortezomib plus rituximab with dexamethasone. Six months after treatments, the central macular volume decreased by 16.1% in the right eye and 28.6% in the left eye on OCT, and the patient’s BCVA was improved to 20/60 in the right eye and 20/400 in the left eye. Very good partial response was obtained after systemic treatment.

CONCLUSION

WM may affect visual function and present as bilateral CRVO. OCTA can show characteristic changes in both retina and choroid vasculatures, which might be of great value for diagnosing or following patients with WM retinopathy. Intravitreal anti-vascular endothelial growth factor treatment combined with systemic therapy might be beneficial for WM patients with retinopathy (SMD and CRVO).

Primary Isolated Lymphoplasmacytic Lymphoma (LPL) of the Stomach: A Case Report

Patient: Male, 47-year-old

Final Diagnosis: LPL of the stomach

Symptoms: Reflux symptoms

Medication:—

Clinical Procedure: —

Specialty: Oncology

Cause-specific mortality in individuals with lymphoplasmacytic lymphoma/Waldenström macroglobulinaemia, 2000-2016

Data on cause-specific mortality after lymphoplasmacytic lymphoma (LPL) and Waldenström macroglobulinaemia (WM) are lacking. We identified causes of death amongst 7289 adults diagnosed with incident first primary LPL (n = 3108) or WM (n = 4181) during 2000-2016 in 17 USA population-based cancer registries. Based on 3132 deaths, 16-year cumulative mortality was 23·2% for lymphomas, 8·4% for non-lymphoma cancers and 14·7% for non-cancer causes for patients aged <65 years at diagnosis of LPL/WM, versus 33·4%, 11·2% and 48·7%, respectively, for those aged ≥75 years. Compared with the general population, patients with LPL/WM had a 20% higher risk of death due to non-cancer causes (n = 1341 deaths, standardised mortality ratio [SMR] 1·2, 95% confidence interval [CI] 1·1-1·2), most commonly from infectious (n = 188; SMR 1·8, 95% CI 1·6-2·1), respiratory (n = 143; SMR 1·2, 95% CI 1·0-1·4), and digestive (n = 80; SMR 1·8, 95% CI 1·4-2·2) diseases, but no excess mortality from cardiovascular diseases (n = 477, SMR 1·1, 95% CI 1·0-1·1). Risks were highest for non-cancer causes within 1 year of diagnosis (n = 239; SMR_<1year 1·3, 95% CI 1·2-1·5), declining thereafter (n = 522; SMR_≥5years 1·1, 95% CI 1·1-1·2). Myelodysplastic syndrome/acute myeloid leukaemia deaths were notably increased (n = 46; SMR 4·4, 95% CI 3·2-5·9), whereas solid neoplasm deaths were only elevated among ≥5-year survivors (n = 145; SMR_≥5years 1·3, 95% CI 1·1-1·5). This work identifies new areas for optimising care and reducing mortality for patients with LPL/WM.

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.

Predictors of symptomatic hyperviscosity in Waldenström macroglobulinemia

Symptomatic hyperviscosity is a well-established phenomenon in Waldenström macroglobulinemia (WM). Monoclonal IgM can variably impact intrinsic serum viscosity, leading to widely disparate symptomatic thresholds for development of hyperviscosity-related symptoms. Data regarding the predictors of symptomatic hyperviscosity and outcomes related to this complication remain scarce and a recent study proposed that IgM >6000 mg/dL be considered a new criterion for initiating therapy in otherwise asymptomatic (smoldering) WM to pre-empt hyperviscosity-related injury. Herein, we attempt to identify predictors of the development of symptomatic hyperviscosity and its impact in patients with WM. Of 997 WM patients evaluated from January, 1996 through June, 2017, symptomatic hyperviscosity was observed in 130 (13%) patients. Overall survival (OS) of these 130 patients was similar to that of patients without symptomatic hyperviscosity (median: 11.5 vs 11.6 years; P = 0.63). On multivariate-analysis, only viscosity >1.8 cp (risk ratio: 4.0, P = 0.02) assessed at the time of WM diagnosis was an independent predictor for the development of subsequent symptomatic hyperviscosity. Among patients with smoldering WM and IgM >6000 mg/dL at diagnosis (n = 13) who were managed expectantly, the median time-to-initial therapy was 6.9 years and only 15% developed hyperviscosity-related symptoms subsequently. In summary, the occurrence of symptomatic hyperviscosity does not impact OS. Serum viscosity at diagnosis of WM, and not IgM concentration, represents the single most important independent predictor for development of subsequent hyperviscosity-related symptoms. Patients with smoldering WM and high serum IgM can be safely observed in the absence of any indications per the Consensus recommendations to initiate WM-directed therapy.

MyD88 Regulates the Expression of SMAD4 and the Iron Regulatory Hormone Hepcidin

The myeloid differentiation primary response gene 88 (MyD88) is an adaptive protein that is essential for the induction of inflammatory cytokines through almost all the Toll-like receptors (TLRs). TLRs recognize molecular patterns present in microorganisms called pathogen-associated molecular patterns. Therefore, MyD88 plays an important role in innate immunity since its activation triggers the first line of defense against microorganisms. Herein, we describe the first reported role of MyD88 in an interconnection between innate immunity and the iron-sensing pathway (BMP/SMAD4). We found that direct interaction of MyD88 with SMAD4 protein activated hepcidin expression. The iron regulatory hormone hepcidin is indispensable for the intestinal regulation of iron absorption and iron recycling by macrophages. We show that MyD88 induces hepcidin expression in a manner dependent on the proximal BMP responsive element on the hepcidin gene (HAMP) promoter. We identified the Toll/interleukin-1 receptor (TIR) domain of MyD88 as the domain of interaction with SMAD4. Furthermore, we show that BMP6 stimulation, which activates SMAD6 expression, also induces MyD88 proteosomal degradation as a negative feedback mechanism to limit hepcidin induction. Finally, we report that the MyD88 gain-of-function L265P mutation, frequently encountered in B-cell lymphomas such as Waldenström’s macroglobulinemia, enhances hepcidin expression and iron accumulation in B cell lines. Our results reveal a new potential role for MyD88 in the SMAD signaling pathway and iron homeostasis regulation.

Neurologic Complications of Lymphoma, Leukemia, and Paraproteinemias

PURPOSE OF REVIEW

This article reviews the spectrum of neurologic complications associated with lymphoma, leukemia, and paraproteinemic disorders. While leptomeningeal metastasis is the most common complication of lymphoma and leukemia and peripheral neuropathy is the most common complication of paraproteinemic disorders, clinicians need to be familiar with the diverse neurologic complications of these disorders.

RECENT FINDINGS

Lymphomatous nervous system involvement can be difficult to diagnose, especially when it is the presenting symptom. CSF cytology and flow cytometry, as well as the imaging pattern, assist in diagnosis. Neurologic complications are less common in Hodgkin lymphoma; however, some unique paraneoplastic syndromes are associated with Hodgkin lymphoma, including primary central nervous system angiitis, limbic encephalitis, and cerebellar degeneration. Recent reports suggest that anti-metabotropic glutamate receptor 5 (mGluR5) antibodies are associated with limbic encephalitis and that anti-Tr antibodies are associated with cerebellar degeneration in Hodgkin lymphoma. Polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, and skin changes (POEMS) syndrome is often misdiagnosed as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). A lambda protein, thrombocytosis, and elevated vascular endothelial growth factor (VEGF) can all be helpful clues in diagnosis. Early recognition is important, as the neuropathy responds to radiation therapy or chemotherapy.

SUMMARY

Neurologic involvement can occur throughout the disease course in lymphoma and leukemia, including at presentation, with systemic progression, and at relapse. In paraproteinemias, the peripheral neuropathy phenotype, monoclonal protein type, and associated autonomic and systemic features aid in identification of an underlying plasma cell disorder.

Lung consolidation as a rare presentation of lymphoplasmacytic lymphoma with extramedullary Waldenström's macroglobulinemia

Objectives: Lymphoplasmacytic lymphoma (LPL) is a mature B cell lymphoma that usually involves the bone marrow, spleen and lymph nodes. Extramedullary involvement, including the lung, is rarely reported.

Case description: A 73-year-old female initially presented to our hospital complaining of productive cough of white-colour sputum for three weeks duration. She reported unintentional weight loss of ten pounds over the last five months. There was no history of haemoptysis, fever, night sweats, chills, recent infections or hospitalization. Chest imaging showed right lower lobe consolidation, small right pleural effusion. She was treated with oral antibiotic for pneumonia. After two months, a follow up chest imaging revealed persistent right lower lobe consolidation. Therefore, she was worked up for the possibility of malignancy. Bronchoscopy showed polypoid nodularities surrounded by black discoloured mucosa in the sub-segmental bronchi of the right lower lobe, and biopsy specimen revealed atypical B cell lymphocytic infiltrate. Polymerase chain reaction confirmed a clonal B-cell gene rearrangement supportive for a low-grade B-cell Lymphoma. Subsequently; serum immunofixation showed IgM of 1491 mg/dL (normal range 26–217 mg/dl) with normal levels of IgG and IgA. Urine contained free kappa light chains. Cytology with immunophenotyping of pleural fluid revealed lymphoplasmacytic lymphocytes. This combination of lab and bronchoscopy findings established the diagnosis of extramedullary Waldenström’s macroglobulinemia.

Conclusion: Waldenström’s macroglobulinemia, a manifestation of LPL, is associated with an IgM monoclonal gammopathy in the blood. Extramedullary involvement including the lung is rarely seen in LPL. Physicians need to be aware of this rare presentation.

Disease spectrum of abnormal serum free light chain ratio and its diagnostic significance

OBJECTIVE

To analyze the spectrum of abnormal serum free light chain ratio (sFLC κ/λ ratio), and to redefine the range of sFLC κ/λ ratio, so as to achieve hierarchical diagnosis of diseases with abnormal sFLC κ/λ ratio, resulting in the increased sensitivity and specificity in the diagnosis of monoclonal plasma diseases.

METHODS

Enrolled 1,340 patients with abnormal sFLC κ/λ ratio (<0.26 or >1.65) were grouped: (1) group A: malignant plasma diseases; (2) group B: monoclonal gammopathies of undetermined significance (MGUS); (3) group C: reactive plasma diseases. These patients were further divided by renal function eGFR <60 or >60 ml/min/1.73m2 to eliminate renal diseases influencing the results. Statistical analyses was performed by using SPSS 22 software.

RESULTS

When sFLC κ/λ ratio >3.49 and eGFR >60ml/min/1.73m2, the sensitivity and specificity of the diagnosis of malignant plasma diseases were 86.1% and 94.0%, respectively. When sFLC κ/λ ratio >2.89 and eGFR <60ml/min/1.73m2, the sensitivity and specificity of the diagnosis of malignant plasma diseases were 92.0% and 97.0%, respectively.

CONCLUSION

The sensitivity and specificity of the diagnosis of monoclonal plasma diseases can be significantly improved by redefining the cut-off value of sFLC κ/λ ratio and the renal function index of eGFR.

Current options to manage Waldenström's macroglobulinemia

INTRODUCTION

Waldenström's macroglobulinemia (WM) is a rare, incurable B-cell lymphoma, with a median survival of 5-10 years in symptomatic patients. There is no consensus on the standard of care and several agents are currently used in these patients. Areas covered: In this article, we will review the use of standard therapies and new drugs investigated such as monoclonal antibodies, proteasome inhibitors, immunomodulatory agents, Bruton's tyrosine kinase inhibitors and novel agents in early-stage development. Expert commentary: RCD (Rituximab/Cyclophosphamide/Dexamethasone) is an effective and safe treatment in first line in WM. BR (Bendamustine/Rituximab) or BRD (Bortezomib/Rituximab/Dexamethasone) provide durable responses, and are still indicated in most patients. Ibrutinib is a new option and it was approved as primary therapy and for relapse. Carfilzomib based therapy represents an emerging option for proteasome-inhibitor based therapy for WM. Despite encouraging results, WM remains an incurable disease; therefore, new treatment options are needed. For this reason, continued participation in clinical trials should be encouraged.

Immunoparesis in IgM gammopathies as a useful biomarker to predict disease progression

Background:

The management of IgM monoclonal gammopathies undetermined significance (IgM-MGUS) and Waldenstrom’s macroglobulinemia (WM) may be challenging. Modern immunoassays that quantify specific monoclonal heavy and light chain immunoglobulins are promising for their use in these applications.

Methods:

Ninety consecutive patients (39 IgM-MGUS, 32 indolent WM [iWM], and 19 WM) seen between January 2007 and March 2014 were analyzed. Heavy/light chain (HLC) and serum free light chains assays (FLC) were determined at diagnosis to study their utility as biomarkers in IgM monoclonal gammopathies.

Results:

The HLC involved to uninvolved IgM ratios (iHLC/uHLC) showed a progressive increase when going from IgM-MGUS, to iWM and to WM (p=0.002). Furthermore, an iHLC/uHLC>62 identified a group of iWM patients with a shorter time-to-progression (TTP) (108 vs. 133 months, p=0.033). Separate analysis of the involved and uninvolved components showed that only the suppression of the uninvolvedimmunoglobulin was predictive of shorter TTP (HR=3.04, p=0.03) suggesting that it could be the majorcontributor to the prognostic value of the Hevylite assay. Additionally, a multivariate analysis showed that immunosuppression (either classical immunoparesis or Hevylite immunosuppression) was an independent prognostic factor (p=0.016) reinforcing its relevance in the disease mechanism. Finally, monoclonal sFLC levels were highest in WM patients, with 83% presenting values>60 mg/L.

Conclusions:

The results suggest that the levels of immunosuppression and/or the iHLC/uHLC ratio of IgM immunoglobulins measured by Hevylite are associated with greater disease activity which significantly impacts in the outcome of WM patients and may also help in the differentiation of IgMMGUS from iWM.

B-cell Non-Hodgkin Lymphomas with Plasmacytic Differentiation

B-cell non-Hodgkin lymphomas with plasmacytic differentiation are a diverse group of entities with extremely variable morphologic features. Diagnostic challenges can arise in differentiating lymphoplasmacytic lymphoma from marginal zone lymphoma and other low-grade B-cell lymphomas. In addition, plasmablastic lymphomas can be difficult to distinguish from diffuse large B-cell lymphoma or other high-grade lymphomas. Judicious use of immunohistochemical studies and molecular testing can assist in appropriate classification.

Allogeneic Transplantation for Relapsed Waldenström Macroglobulinemia and Lymphoplasmacytic Lymphoma

Waldenström macroglobulinemia/lymphoplasmacytic lymphoma (WM/LPL) is characterized by lymphoplasmacytic proliferation, lymph node and spleen enlargement, bone marrow involvement, and IgM production. Treatment varies based on the extent and biology of disease. In some patients, the use of allogeneic hematopoietic cell transplantation (alloHCT) may have curative potential. We evaluated long-term outcomes of 144 patients who received adult alloHCT for WM/LPL. Data were obtained from the Center for International Blood and Marrow Transplant Research database (2001 to 2013). Patients received myeloablative(n = 67) or reduced-intensity conditioning (RIC; n = 67). Median age at alloHCT was 53 years, and median time from diagnosis to transplantation was 41 months. Thirteen percent (n = 18) failed prior autologous HCT. About half (n = 82, 57%) had chemosensitive disease at the time of transplantation, whereas 22% had progressive disease. Rates of progression-free survival, overall survival, relapse, and nonrelapse mortality at 5 years were 46%, 52%, 24%, and 30%, respectively. Patients with chemosensitive disease and better pretransplant disease status experienced significantly superior overall survival. There were no significant differences in progression-free survival based on conditioning (myeloablative, 50%, versus RIC, 41%) or graft source. Conditioning intensity did not impact treatment-related mortality or relapse. The most common causes of death were primary disease and graft-versus-host disease (GVHD). AlloHCT yielded durable survival in select patients with WM/LPL. Strategies to reduce mortality from GVHD and post-transplant relapse are necessary to improve this approach.

The role of stem cell transplantation in Waldenstrom's macroglobulinemia

Waldenstrom's macroglobulinemia (WM) is an indolent B-cell lymphoma, which is highly chemosensitive, with an overall response rate over 90% to novel agents. However, most patients eventually relapse after response to first-line chemotherapy, necessitating further treatment. The possibility of long-lasting remission after high-dose cytotoxic chemotherapy followed by stem cell rescue is high in WM due to the chemosensitive nature of the disease and lower proliferative activity compared to multiple myeloma. In this paper, we have reviewed current evidence on autologous (auto-) and allogeneic (allo-) stem cell transplantation (SCT) in WM. Auto-SCT can be safely performed in WM and is recommended as second-line treatment or beyond in eligible patients. It is associated with extremely low transplant-related mortality. Allo-SCT is effective in WM with incremental benefit due to graft-versus-WM effect, but is associated with high non-relapse mortality of 30%, hence should be preferably considered investigational as part of clinical trials in selected patients who have exhausted other treatment options.

Issues in diagnosis of small B cell lymphoid neoplasms involving the bone marrow and peripheral blood. Report on the Bone Marrow Workshop of the XVIIth meeting of the European Association for Haematopathology and the Society for Hematopathology

Small B cell lymphoid neoplasms are the most common lymphoproliferative disorders involving peripheral blood (PB) and bone marrow (BM). The Bone Marrow Workshop (BMW) organized by the European Bone Marrow Working Group (EBMWG) of the European Association for Haematopathology (EAHP) during the XVIIth EAHP Meeting in Istanbul, October 2014, was dedicated to discussion of cases illustrating how the recent advances in immunophenotyping, molecular techniques and cytogenetics provide better understanding and classification of these entities. Submitted cases were grouped into following categories: (i) cases illustrating diagnostic difficulties in chronic lymphocytic leukaemia (CLL); (ii) cases of BM manifestations of small B cell lymphoid neoplasms other than CLL; (iii) transformation of small B cell lymphoid neoplasms in the BM; and (iv) multiclonality and composite lymphomas in the BM. This report summarizes presented cases and conclusions of the BMW and provides practical recommendations for classification of the BM manifestations of small B cell lymphoid neoplasms based on the current state of knowledge.

Exome sequencing reveals recurrent germ line variants in patients with familial Waldenström macroglobulinemia

Familial aggregation of Waldenström macroglobulinemia (WM) cases, and the clustering of B-cell lymphoproliferative disorders among first-degree relatives of WM patients, has been reported. Nevertheless, the possible contribution of inherited susceptibility to familial WM remains unrevealed. We performed whole exome sequencing on germ line DNA obtained from 4 family members in which coinheritance for WM was documented in 3 of them, and screened additional independent 246 cases by using gene-specific mutation sequencing. Among the shared germ line variants, LAPTM5(c403t) and HCLS1(g496a) were the most recurrent, being present in 3/3 affected members of the index family, detected in 8% of the unrelated familial cases, and present in 0.5% of the nonfamilial cases and in <0.05 of a control population. LAPTM5 and HCLS1 appeared as relevant WM candidate genes that characterized familial WM individuals and were also functionally relevant to the tumor clone. These findings highlight potentially novel contributors for the genetic predisposition to familial WM and indicate that LAPTM5(c403t) and HCLS1(g496a) may represent predisposition alleles in patients with familial WM.

Emerging therapeutic options for Waldenström macroglobulinemia/lymphoplasmacytic lymphoma

Lymphoplasmacytic lymphoma is an indolent B-cell, non-Hodgkin lymphoma (NHL), the majority of which are characterized by production of a monoclonal immunoglobulin M (IgM) protein and are known as Waldenström macroglobulinemia. Identification of highly recurrent activating somatic mutation in MYD88 has improved our understanding of the pathogenesis of Waldenström macroglobulinemia and has therapeutic implications. Here, we review novel therapeutic agents in Waldenström macroglobulinemia/lymphoplasmacytic lymphoma, which have emerged in the past decade and discuss their comparative efficacy and safety, with emphasis on a Bruton's tyrosine kinase (BTK) inhibitor, which has been recently approved by the US FDA, specifically for Waldenström macroglobulinemia/lymphoplasmacytic lymphoma. Future research should focus on identifying targeted agents against activating mutations and long-term data for currently available novel agents should be critically evaluated, both in treatment-naïve and in relapsed/refractory settings.

Ibrutinib for the treatment of Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is a B-cell non-Hodgkin lymphoma (NHL) characterized by IgM monoclonal gammopathy and bone marrow infiltration by lymphoplasmacytic cells. Until recently, there was no drug specifically approved for WM by the US FDA, leading to wide variations in therapeutic strategies across the globe. Ibrutinib, an oral Bruton tyrosine kinase (BTK) inhibitor, is the first drug approved specifically for WM by the FDA after a clinical trial showed impressive response in previously treated WM. Ibrutinib is a non-stem cell toxic and non-neurotoxic option and suitable for long-term oral maintenance therapy, with the potential of improving survival in WM. With identification of novel genetic mutations impacting response to ibrutinib, it would be possible to individualize therapy based on MYD88 and CXCR4 genotypes. However, long-term safety and efficacy data are required, and cost-effectiveness needs to be addressed before ibrutinib can gain widespread acceptance for front-line therapy of WM.