Bortezomib is active in patients with untreated or relapsed Waldenstrom's macroglobulinemia: a phase II study of the National Cancer Institute of Canada Clinical Trials Group

Waldenström macroglobulinemia: a review of pathogenesis, current treatment, and future prospects

Waldenström macroglobulinemia (WM) is a chronic B-cell lymphoproliferative disorder characterized by lymphoplasmacytic cell overgrowth in the bone marrow and increased secretion of IgM immunoglobulins into the serum. Patients with WM have a variety of clinical outcomes, including long-term survival but inevitable recurrence. Recent advances in disease knowledge, including molecular and genetic principles with the discovery of MYD88 and CXCR4 mutations, have rapidly increased patient-tolerable treatment options. WM patients may benefit from chemotherapy regimens that include rituximab-based regimens, alkylating drugs, proteasome inhibitors, monoclonal antibodies, and drugs targeting Bruton tyrosine kinase inhibitors. In light of these advancements, patients can now receive treatment customized to their specific clinical characteristics, focusing on enhancing the depth and durability of their response while limiting the adverse effects. Despite the rapidly developing therapeutic armament against WM, a lack of high-quality evidence from extensive phase 3 trials remains a significant challenge in the research. We believe clinical outcomes will keep improving when new medicines are introduced while preserving efficacy and minimizing toxicity.

Current approach to Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is a unique CD20+, B-cell non-Hodgkin lymphoma, characterized by lymphoplasmacytic infiltration of the bone marrow and circulating monoclonal immunoglobulin M. The clinical manifestations and outcomes of patients are highly variable. High-level evidence supports integration of monoclonal anti-CD20 antibody, rituximab, to the chemotherapy backbone to treat WM. However, its contemporary management has become more nuanced, with deeper understanding of the pathophysiology and incorporation of Bruton's tyrosine kinase (BTK) inhibitors to the treatment paradigm. Prior knowledge of the patients' MYD88L265P and CXCR4 mutation status may aid in the treatment decision-making. Currently, the two frequently utilized approaches include fixed-duration chemoimmunotherapy and BTK inhibitor-based continuous treatment until progression. Randomized trials comparing these two vastly divergent approaches are lacking. Recent studies demonstrating efficacy of B cell lymphoma-2 (BCL2) inhibitors and non-covalent BTK inhibitors in patients, previously exposed to a covalent BTK inhibitor, are a testament to the rapidly expanding options against WM.

The Management of Relapsed or Refractory Waldenström's Macroglobulinemia

Waldenström's macroglobulinemia (WM) is an immunoglobulin M monoclonal gammopathy produced by a bone marrow lymphoplasmacytic lymphoma, an indolent non-Hodgkin lymphoma in which the cure is still an unmet challenge. Combinations with alkylating agents, purine analogs, and monoclonal antibodies, Bruton tyrosine kinase, and proteasome inhibitors are used for the treatment of relapsed and refractory patients. Moreover, new additional agents can be seen on the horizon as potential effective therapies. No consensus on a preferred treatment in the relapsed setting is available yet.

Proteasome Inhibitor-Based Regimens in the Frontline Management of Waldenström Macroglobulinemia

Proteasome inhibitors (PIs) have long been used in myeloma therapy but also for Waldenström macroglobulinemia. Their use has been successful and has also been investigated for the frontline management of the disease. Bortezomib was effective either as a single agent or in combination with other regimens with high response rates observed in most studies, despite its adverse effects, especially neurotoxicity, which remains a major concern. Clinical trials with second-generation PIs such as carfilzomib and ixazomib have also been conducted, always in combination with immunotherapy in previously untreated patients. They have been shown to be active and neuropathy-sparing treatment options.

Minimal residual disease status improved the response evaluation in patients with Waldenström's macroglobulinemia

Introduction

Minimal residual disease (MRD) has been recognized as an important prognostic factor of survival in patients with hematological malignancies. However, the prognostic value of MRD in Waldenström macroglobulinemia (WM) remains unexplored.

Methods

We analyzed 108 newly diagnosed WM patients receiving systematic therapy and assessed for MRD by multiparameter flow cytometry (MFC) using bone marrow samples.

Results

Of the total patients, 34 (31.5%) achieved undetectable MRD (uMRD). A hemoglobin level of >115 g/L (P=0.03), a serum albumin level of >35 g/L (P=0.01), a β2-MG level of ≤3 mg/L (P=0.03), and a low-risk International Prognostic Scoring System for WM (IPSSWM) stage (P<0.01) were associated with a higher rate of uMRD. Improvements in monoclonal immunoglobulin (P<0.01) and hemoglobin (P=0.03) levels were more evident in uMRD patients compared with that in MRD-positive patients. The 3-year progression-free survival (PFS) was better in uMRD patients compared with that in MRD-positive patients (96.2% vs. 52.8%; P=0.0012). Landmark analysis also showed that uMRD patients had better PFS compared with MRD-positive patients after 6 and 12 months. Patients who achieved partial response (PR) and uMRD had a 3-year PFS of 100%, which was significantly higher than that of patients with MRD-positive PR (62.6%, P=0.029). Multivariate analysis showed that MRD positivity was an independent factor of PFS (HR: 2.55, P=0.03). Moreover, the combination of the 6th International Workshop on WM assessment (IWWM-6 Criteria) and MRD assessment had a higher 3-year AUC compared with the IWWM-6 criteria alone (0.71 vs. 0.67).

Discussion

MRD status assessed by MFC is an independent prognostic factor for PFS in patients with WM, and its determination could improve the precision of response evaluation, especially in patients who achieved PR.

Treatment of relapsed and refractory Waldenstrom Macroglobulinemia

Waldenström's Macroglobulinemia (WM) is a rare type of indolent non-Hodgkin lymphoma (NHL) that remains incurable. Several effective agents such as monoclonal antibodies (in combination with chemotherapy), Bruton's tyrosine kinase inhibitors, proteasome inhibitors, and BCL2 inhibitors are (becoming) available for the treatment of relapsed and refractory WM. There is however no consensus on a preferred treatment in the relapsed setting. Choice of therapy in relapsed WM should be individualized by taking several treatment and patients characteristics into account, such as treatment duration, toxicity, age, comorbidities and MYD88^L265P and CXCR4 mutational status. Due to better understanding of WM biology and the arrival of novel anti-lymphoma agents, the therapeutic options are increasing. Non-cytotoxic and fixed duration regimens, such as those explored in other indolent NHLs should be the focus of future clinical trials in WM.

Bortezomib-based chemotherapy for patients with Waldenström macroglobulinemia: a single-center experience

Waldenström Macroglobulinemia (WM) is a rare type of non-Hodgkin lymphoma with no standard first-line treatment, and the disease is still incurable. This study evaluated the clinical efficacy, safety, and prognostic factors of bortezomib-based chemotherapy as initial treatment in WM patients. We retrospectively analyzed the clinical data collected from 44 newly diagnosed WM patients treated with bortezomib-based regimens at the Affiliated Hospital of Nantong University from December 2011 to June 2021. Univariate and multivariate analyses were used to assess prognostic factors for overall survival (OS) and progression-free survival (PFS). The median age was 67 years old, with an overall response rate (ORR) of 93.2%, complete response (CR) rate of 6.8%, and very good partial response (VGPR) rate of 29.5%. With a median follow-up of 39 months, the 2-year overall survival (OS) and 2-year PFS rates were 88.0% and 59.0%, respectively. By the last follow-up, eight patients (18.2%) had died. Univariate analysis showed patients with B symptoms, elevated LDH, international prognostic stage system of WM (IPSSWM) stage III, high Revised IPSSWM (R-IPSSWM) score, and those who did not achieve VGPR were associated with shorter PFS. And patients with B symptoms, with high R-IPSSWM score, and who do not achieve VGPR also had shorter OS than their counterparts. Multivariate analysis confirmed that failure to achieve VGPR was an independent adverse prognostic factor for OS and PFS. In conclusion, we showed that bortezomib-based chemotherapy effectively treated newly diagnosed patients with WM. However, combinations of drugs with different mechanisms are recommended for patients with a high tumor burden. In addition, deep remission can improve patients' survival.

A Canadian Perspective on the Treatment of Waldenström Macroglobulinemia

Waldenström macroglobulinemia (WM) is a slowly progressing B-cell non-Hodgkin lymphoma characterized by monoclonal IgM gammopathy in the blood and infiltration of the bone marrow by clonal lymphoplasmacytic cells. As an incurable disease, the goals for therapy for WM are to relieve symptoms, slow disease progression, prevent organ damage, and maintain quality of life. However, given the rarity of WM, clinical trials comparing treatments for WM are limited and there is no definitive standard of care. The selection of first-line WM therapy is thus based on patient factors, disease characteristics, and drug access, with bendamustine-rituximab and Bruton's tyrosine kinase (BTK) inhibitor therapy considered preferred treatments. Other treatments such as proteasome inhibitor- or purine analogue-based therapy, alternative chemoimmunotherapy, and autologous stem cell transplantation are generally reserved for the relapsed setting but may be used in rare circumstances in earlier lines of therapy. This paper summarizes the efficacy and safety of these WM therapies and discusses considerations for treatment from a Canadian perspective.

Zanubrutinib in Treating Waldenström Macroglobulinemia, the Last Shall Be the First

In Waldenström macroglobulinemia (WM), a lymphoplasmacytic lymphoma characterized by monoclonal immunoglobulin M (IgM) gammopathy, aberrant Bruton tyrosine kinase (BTK) signaling has been identified as one mechanism of pathogenesis. For this reason, selective BTK inhibiting therapies have emerged as an attractive option for treatment within the therapeutic landscape also comprising chemotherapy, monoclonal antibodies, proteasome inhibitors, and B-cell lymphoma 2 (BCL2) inhibitors. The first BTK inhibiting therapy, ibrutinib, showed great efficacy in treating WM. However, response rates were dependent on whether patients had the CXCR4 mutation, a molecular aberration that may confer resistance to BTK inhibitors. Furthermore, ibrutinib’s toxicities, most notably hypertension and atrial arrhythmia, led to dose reductions or discontinuation. The toxicity profile of ibrutinib can be attributed to the inhibition of additional kinases that are structurally related to BTK. Therefore, the next-generation highly selective zanubrutinib was developed to address the concerns regarding toxicity and tolerance related to ibrutinib therapy. Based on the results of the randomized, open-label Phase 3 ASPEN (NCT03053440) trial, the Food and Drug Administration (FDA) approved zanubrutinib for treating WM. This trial directly compared zanubrutinib to ibrutinib in patients with treatment-naïve or relapsed/refractory WM, and the results showed stronger responses with zanubrutinib. More importantly, patients responded strongly to zanubrutinib therapy regardless of CXCR4 mutation status. Additionally, zanubrutinib was associated with fewer grade 3 or higher toxicities and was generally better tolerated. Another Phase 1/2 study has been conducted with just zanubrutinib in WM showcasing high efficacy with few toxicities as well. Even though zanubrutinib has been the third and last BTK inhibitor to currently penetrate the market for B-cell lymphoproliferative malignancies, we highlight the emergence of zanubrutinib as a key player in the forefront of the therapeutic landscape in WM.

Diagnosis and management of Waldenström macroglobulinaemia-A British Society for Haematology guideline

SCOPE

The objective of this guideline is to provide healthcare professionals with clear guidance on the management of patients with Waldenström macroglobulinaemia. In individual patients, circumstances may dictate an alternative approach.

METHODOLOGY

This guideline was compiled according to the British Society for Haematology (BSH) process at http://www.b-s-h.org.uk/guidelines/proposing-and-writing-a-new-bsh-guideline/. Recommendations are based on a review of the literature using Medline, Pubmed, Embase, Central, Web of Science searches from beginning of 2013 (since the publication of the previous guidelines) up to November 2021. The following search terms were used: Waldenström('s) macroglobulin(a)emia OR lymphoplasmacytic lymphoma, IgM(-related) neuropathy OR cold h(a)emagglutinin disease OR cold agglutinin disease OR cryoglobulin(a)emia AND (for group a only) cytogenetic OR molecular OR mutation OR MYD88 OR CXCR4, management OR treatment OR transfusion OR supportive care OR plasma exchange OR plasmapheresis OR chemotherapy OR bendamustine OR bortezomib OR ibrutinib OR fludarabine OR dexamethasone OR cyclophosphamide OR rituximab OR everolimus, bone marrow transplantation OR stem cell transplantation. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) nomenclature was used to evaluate levels of evidence and to assess the strength of recommendations. The GRADE criteria can be found at http://www.gradeworkinggroup.org. Review of the manuscript was performed by the British Society for Haematology (BSH) Guidelines Committee Haemato-Oncology Task Force, the BSH Guidelines Committee and the Haemato-Oncology sounding board of BSH. It was also on the members section of the BSH website for comment. It has also been reviewed by UK Charity WMUK; these organisations do not necessarily approve or endorse the contents.

Use of BTK inhibitors with special focus on ibrutinib in Waldenström macroglobulinemia: an expert panel opinion statement

The pivotal role that ibrutinib plays in the management of Waldenström macroglobulinemia (WM) is undisputed but there are ongoing questions regarding its positioning in the therapeutic algorithm of WM as well as in some peculiar clinical situations. A panel of experts from Italy was convened to provide real world recommendations on the use of BTK inhibitors in lymphoproliferative diseases in general, and in patients with WM in particular. This position paper represents the panel's collective analysis, evaluation, and opinions and is made up of a series of questions frequently asked by practicing clinicians and answers based on currently available evidence. This article is protected by copyright. All rights reserved.

Current approach to Waldenström Macroglobulinemia

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

Differential Diagnosis of Waldenström's Macroglobulinemia and Early Management: Perspectives from Clinical Practice

Waldenström's Macroglobulinemia (WM) is a clonal B-lymphocyte neoplasm characterized by the presence of IgM monoclonal protein and ≥10% bone marrow involvement with lymphoplasmacytic cells. Several mature B-cell and plasma cell disorders can potentially produce monoclonal IgM immunoglobulin and hence, careful consideration of the differential diagnosis is vital. Clinico-pathological features, immunophenotype, and MYD88 mutation status help distinguish WM from other plasma cell and lymphoproliferative disorders. Treatment is only indicated in patients symptomatic from adenopathy or organomegaly, neuropathy, hyper viscosity, cryoglobulinemia, cold agglutinin disease, cytopenia's or amyloidosis. Alkylators (cyclophosphamide, bendamustine) in combination with anti-CD20 antibodies and novel targeted agents including Bruton tyrosine kinase (BTK) inhibitors like ibrutinib are the mainstay of frontline treatment in symptomatic WM.

Protein clearance strategies for disease intervention

Protein homeostasis, or proteostasis, is essential for cell function and viability. Unwanted, damaged, misfolded and aggregated proteins are degraded by the ubiquitin–proteasome system (UPS) and the autophagy-lysosome pathway. Growing evidence indicates that alterations in these major proteolytic mechanisms lead to a demise in proteostasis, contributing to the onset and development of distinct diseases. Indeed, dysregulation of the UPS or autophagy is linked to several neurodegenerative, infectious and inflammatory disorders as well as cancer. Thus, modulation of protein clearance pathways is a promising approach for therapeutics. In this review, we discuss recent findings and open questions on how targeting proteolytic mechanisms could be applied for disease intervention.

How to Sequence Therapies in Waldenström Macroglobulinemia

OPINION STATEMENT

There are multiple treatment options in patients with Waldenström macroglobulinemia, including chemotherapy, monoclonal antibodies, proteasome inhibitors, and covalent Bruton tyrosine kinase (BTK) inhibitors. The choice of therapy should take into account the patient's clinical presentation, comorbidities, and preferences. A thorough discussion should take place to outline the administration, safety, and efficacy of the regimens under consideration. The patient's genomic profile can provide insightful information for the treatment selection. In the frontline and relapsed settings, we favor ibrutinib monotherapy over chemoimmunotherapy or proteasome inhibitor-based regimens in patients with MYD88 and without CXCR4 mutations. For patients with MYD88 and CXCR4 mutations or without MYD88 or CXCR4 mutations, chemoimmunotherapy or proteasome inhibitor-based regimens are favored, but efficacy data with ibrutinib in combination with rituximab and with novel covalent BTK inhibitors are emerging. Autologous stem cell transplant should be considered in special cases in the relapsed setting. Participation in clinical trials is positively encouraged in WM patients in frontline and relapsed settings. Agents of interest include the BCL2 antagonist venetoclax, the CXCR4 inhibitor mavorixafor, and the non-covalent BTK inhibitors pirtobrutinib and ARQ-531.

Corneal nerve changes following treatment with neurotoxic anticancer drugs

Survival rates of cancer has improved with the development of anticancer drugs including systemic chemotherapeutic agents. However, long-lasting side effects could impact treated patients. Neurotoxic anticancer drugs are specific agents which cause chemotherapy-induced peripheral neuropathy (CIPN), a debilitating condition that severely deteriorates quality of life of cancer patients and survivors. The ocular surface is also prone to neurotoxicity but investigation into the effects of neurotoxic chemotherapy on the ocular surface has been more limited compared to other systemic etiologies such as diabetes. There is also no standardized protocol for CIPN diagnosis with an absence of a reliable, objective method of observing nerve damage structurally. As the cornea is the most densely innervated region of the body, researchers have started to focus on corneal neuropathic changes that are associated with neurotoxic chemotherapy treatment. In-vivo corneal confocal microscopy enables rapid and objective structural imaging of ocular surface microscopic structures such as corneal nerves, while esthesiometers provide means of functional assessment by examining corneal sensitivity. The current article explores the current guidelines and gaps in our knowledge of CIPN diagnosis and the potential role of in-vivo corneal confocal microscopy as a diagnostic or prognostic tool. Corneal neuropathic changes with neurotoxic anticancer drugs from animal research progressing through to human clinical studies are also discussed, with a focus on how these data inform our understanding of CIPN.

Reducing treatment toxicity in Waldenström macroglobulinemia

Introduction: Waldenström macroglobulinemia (WM) is a rare subtype of non-Hodgkin lymphoma characterized by the presence of IgM-secreting clonal lymphocytes, plasma cells, and lymphoplasmacytic cells. Many well-established treatment options are available for patients with WM. However, a unique array of side effects may occur in patients during therapy related to the underlying disease, as well as the chosen treatment regimen.Areas covered: This review summarizes the most common adverse effects that occur during treatment of WM, as well as potential strategies to decrease the risk of toxicity.Expert opinion: There are multiple highly effective treatment options for patients with WM. All these treatment options, however, can be associated with a variety of adverse events. For example, chemotherapy has been associated with the development of myeloid neoplasms, anti-CD20 monoclonal antibodies with paradoxical IgM flares and infusion reactions, proteasome inhibitors with neuropathy, and BTK inhibitors with bleeding and cardiac arrhythmias. Dose reductions, lower number of cycles and changes in route of administration are some of the tools a clinician has available for managing and minimizing toxicity. Future research will focus on improving patient safety without sacrificing the efficacy of treatment.

CXCR4 in Waldenström's Macroglobulinema: chances and challenges

It is one of the major aims in cancer research to improve our understanding of the underlying mechanisms which initiate and maintain tumor growth and to translate these findings into novel clinical diagnostic and therapeutic concepts with the ultimate goal to improve patient care. One of the greater success stories in this respect has been Waldenström's Macroglobulinemia (WM), which is an incurable B-cell neoplasm characterized by serum monoclonal immunoglobulin M (IgM) and clonal lymphoplasmacytic cells infiltrating the bone marrow. Recent years have succeeded to describe the molecular landscape of WM in detail, highlighting two recurrently mutated genes, the MYD88 and the CXCR4 genes: MYD88 with an almost constant and recurrent point mutation present in over 90% of patients and CXCR4 with over 40 different mutations in the coding region affecting up to 40% of patients. Intriguingly, both mutations are activating mutations leading in the case of CXCR4 to an indelible activation and perpetual signaling of the chemokine receptor. These data have shed light on the essential role of CXCR4 in this disease and have paved the way to use these findings for predicting treatment response to the Bruton tyrosine kinase (BTK) inhibitor ibrutinib and novel therapeutic approaches in WM, which might be transferable to other related CXCR4 positive diseases. Well known for its central role in cancer progression and distribution, CXCR4 is highlighted in this review with regard to its biology, prognostic and predictive relevance and therapeutic implications in WM.

Current and Emerging Treatments for Waldenström Macroglobulinemia

Waldenström macroglobulinemia (WM) is a rare lymphoplasmacytic lymphoma. The primary goal of therapy is to reduce symptoms related to direct infiltration of the bone marrow and decrease monoclonal IgM-associated complications. Active agents in the management of WM can be broadly classified as rituximab-alkylator combination therapy, proteasome inhibitor-based therapy, and Bruton's tyrosine kinase inhibitor-based therapy. MYD88L265P and CXCR4 genetic status are pivotal for tailoring treatment options. Ibrutinib is a suitable treatment option for both treatment-naïve and relapsing WM patients. Recent advances in the intracellular B cell and cytokine signaling pathways have contributed to the development of novel therapeutic strategies. Current clinical trials are promising and may further advance WM-directed therapy.

Novel tumor-targeted liposomes comprised of an MDM2 antagonist plus proteasome inhibitor display anti-tumor activity in a xenograft model of bortezomib-resistant Waldenstrom macroglobulinemia

Targeted drug delivery remains an active area of investigation in hematologic cancers. We have previously reported on a novel nanoparticle formulation (D1X) that can encapsulate drugs within a liposome whose lipid bilayer contains dexamethasone, which serves as a targeting ligand for drug delivery to tumor cells that express glucocorticoid receptors. We tested the activity of D1X-encapsulated bortezomib (D1XB) in combination with D1X-encapsulated nutlin (D1XN) in B-lymphoma/Waldenstrom macroglobulinemia (WM) cells. WM cells treated with D1XB + D1XN experienced cell cycle arrest, ER stress and apoptosis. In mice xenografted with bortezomib-resistant WM cells, D1XB + D1XN treatment resulted in significantly lower tumor burden compared to vehicle or nonliposomal parent drugs. In vivo biodistribution studies showed minimal uptake of D1X-based drugs in normal mice tissues. Our studies demonstrate that highly targeted delivery of both bortezomib and nutlin encapsulated in D1X nanoparticles are cytotoxic to and delay in vivo growth of bortezomib-resistant WM cells.

Clinical Pharmacokinetics and Pharmacodynamics of Bortezomib

Proteasome inhibitors disrupt multiple pathways in cells and the bone marrow microenvironment, resulting in apoptosis and inhibition of cell-cycle progression, angiogenesis, and proliferation. Bortezomib is a first-in-class proteasome inhibitor approved for the treatment of multiple myeloma and mantle cell lymphoma after one prior therapy. It is also effective in other plasma cell disorders and non-Hodgkin lymphomas. The main mechanism of action of bortezomib is to inhibit the chymotrypsin-like site of the 20S proteolytic core within the 26S proteasome, thereby inducing cell-cycle arrest and apoptosis. The pharmacokinetic profile of intravenous bortezomib is characterized by a two-compartment model with a rapid initial distribution phase followed by a longer elimination phase and a large volume of distribution. Bortezomib is available for subcutaneous and intravenous administration. Pharmacokinetic studies comparing subcutaneous and intravenous bortezomib demonstrated that systemic exposure was equivalent for both routes; pharmacodynamic parameters of 20S proteasome inhibition were also similar. Renal impairment does not influence the intrinsic pharmacokinetics of bortezomib. However, moderate or severe hepatic impairment causes an increase in plasma concentrations of bortezomib. Therefore, patients with moderate or severe hepatic impairment should start at a reduced dose. Because bortezomib undergoes extensive metabolism by hepatic cytochrome P450 3A4 and 2C19 enzymes, certain strong cytochrome P450 3A4 inducers and inhibitors can also alter the systemic exposure of bortezomib. This article critically reviews and summarizes the clinical pharmacokinetics and pharmacodynamics of bortezomib at various dosing levels and routes of administration as well as in specific patient subsets. In addition, we discuss the clinical efficacy and safety of bortezomib.

Bortezomib for the Treatment of Hematologic Malignancies: 15 Years Later

Bortezomib is a dipeptidyl boronic acid that selectively inhibits the ubiquitin proteasome pathway, which plays a role in the degradation of many intracellular proteins. It is the first-in-class selective and reversible inhibitor of the 26S proteasome, with antiproliferative and antitumor activity. It exerts its anti-neoplastic action mainly via the inhibition of the nuclear factor-κB pathway components associated with cell proliferation, apoptosis, and angiogenesis. The drug has revolutionized the treatment of multiple myeloma and, more recently, mantle cell lymphoma. In 2003, bortezomib received accelerated approval from the US Food and Drug Administration for the treatment of relapsed/refractory multiple myeloma and in 2008 for patients with previously untreated multiple myeloma. In 2006, bortezomib was approved for the treatment of refractory/relapsed mantle cell lymphoma and, in 2014, for previously untreated mantle cell lymphoma. Bortezomib has also demonstrated clinical efficacy both as a single drug and in combination with other agents in light chain amyloidosis, lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia, and peripheral T-cell lymphomas. Furthermore, continued clinical studies are required to confirm its value for patients with indolent and aggressive B-cell non-Hodgkin lymphomas and acute leukemias.

Clinical Pharmacokinetic and Pharmacodynamic Considerations in Treating Non-Hodgkin Lymphoma

Non-Hodgkin lymphoma (NHL) includes a variety of closely related malignancies that originate from lymphoid precursors. The majority of NHLs are of B-cell lineage, for which traditional therapy involves chemotherapy in combination with the anti-CD20 monoclonal antibody rituximab. Ongoing research into the pathogenesis of NHL subtypes has given rise to the use of novel agents that target specific molecular pathways. While the incidence of NHL extends over a range of ages from pediatric to elderly settings, the majority of diagnoses occur over age 60 years. Increasing the use of concomitant medication coupled with declining organ function among this group of patients creates pharmacokinetic (PK) challenges in administering a number of agents involved in the treatment of NHL. In addition, since many of the new agents are administered orally, there are a number of added PK factors that must be taken into consideration with their prescribing and administration. This article will review the available literature on the PK and pharmacodynamic properties of agents commonly used in the treatment of NHL, and intends to provide information that can assist with properly using these drugs in this setting.

Proteasome Inhibitors in Waldenström Macroglobulinemia

Waldenström macroglobulinemia (WM) remains an incurable B-cell lymphoproliferative disorder, yet therapy is only considered for patients with symptomatic disease. Primary therapy options for WM include combinations based on anti-CD20 monoclonal antibodies, mainly rituximab. However, proteasome inhibitors have become an important part of WM therapy both as primary therapy and as salvage option. Bortezomib is the proteasome inhibitor most studied and with extensive clinical experience, but new proteasome inhibitors (carfilzomib, ixazomib, oprozomib), with different toxicity profiles, routes of administration, and probably with preserved or improved activity, have become available and may also find their way into WM therapy.

A safety profile of medications used to treat Waldenström's macroglobulinemia

INTRODUCTION

Waldenström's macroglobulinemia (WM) is a B-cell lymphoproliferative disease with serum IgM monoclonal component and bone marrow infiltration by lymphoplasmacytic lymphoma. Traditional therapy was based on that regimens used for closely related entities, such as chronic lymphocytic leukemia or multiple myeloma. This resulted in a lack of drugs specifically approved for WM, until the discovery of the Bruton Tyrosine Kinase (BTK) inhibitors.

AREAS COVERED

Two main therapeutic attitudes are possible: (1) conventional therapies based on combinations with alkylating agents or proteasome inhibitors with steroids and anti-CD20 monoclonal antibodies or (2) new approaches with BTK inhibitors, usually alone. Other possibilities such as BCL2 inhibitors, PI3K/AKT inhibitors, and others are currently under evaluation, but we will focus the review on the most consolidated approaches that are available for patients with WM at different stages of the disease. PubMed, Web of Science, and clinicaltrials.gov were queried for the keywords 'Waldenstrom macroglobulinemia' and the different drugs here evaluated through 1 February 2018.

EXPERT OPINION

Although WM has no many specific drugs, there are many possible therapies, including Ibrutinib, the first formally approved drug for this disorder.

The importance of the genomic landscape in Waldenström's Macroglobulinemia for targeted therapeutical interventions

The Literature has recently reported on the importance of genomics in the field of hematologic malignancies, including B-cell lymphoproliferative disorders such as Waldenström's Macrolgobulinemia (WM). Particularly, whole exome sequencing has led to the identification of the MYD88L265P and CXCR4C1013G somatic variants in WM, occurring in about 90% and 30% of the patients, respectively. Subsequently, functional studies have demonstrated their functional role in supporting WM pathogenesis and disease progression, both in vitro and in vivo, thus providing the pre-clinical evidences for extremely attractive targets for novel therapeutic interventions in WM. Of note, recent evidences have also approached and defined the transcriptome profiling of WM cells, revealing a signature that mirrors the somatic aberrations demonstrated within the tumor clone. A parallel research field has also reported on microRNAs (miRNAs), highlighting the oncogenic role of miRNA-155 in WM. In the present review, we focus on the latest reports on genomics and miRNAs in WM, providing an overview of the clinical relevance of the latest acquired knowledge about genomics and miRNA aberrations in WM.

Low-dose bortezomib and dexamethasone as primary therapy in elderly patients with Waldenstrӧm macroglobulinemia

OBJECTIVE

This retrospective study was designed to determine the efficacy and safety of low-dose bortezomib and dexamethasone (lBD) in elderly Chinese patients with Waldenstrӧm macroglobulinemia (WM).

METHODS

Ten patients with WM aged over 60 years received first-line treatment with lBD.

RESULTS

The median age was 70 years (range, 61-77 years). The overall response rate was 80%, including 1 patient who achieved a complete response, 1 patient with very good partial response, and 6 patients with a partial response. Median time to response was 1.8 months after treatment with lBD. Six (60%) patients achieved a partial response, including 2 (20%) patients who had a more than 75% reduction in serum immunoglobulin M levels. A rapid reduction in paraprotein was observed in three patients who received plasmapheresis. After a median follow-up period of 36 months, all patients were still alive and six had no disease progression. The estimated median time to progression was 39 months (range, 15-60 months). The most common adverse events were anemia, thrombocytopenia, neuropathy, and neutropenia. Peripheral neuropathy was the most common non-hematological toxicity in six (60%) patients, but did not result in the discontinuation of bortezomib.

CONCLUSIONS

Our findings show that lBD is an effective and tolerable treatment regimen for elderly patients with WM.

Dexamethasone, rituximab and cyclophosphamide for relapsed and/or refractory and treatment-naïve patients with Waldenstrom macroglobulinemia

The management of Waldenström macroglobulinaemia (WM) relies predominantly on small trials, one of which has demonstrated activity of dexamethasone, rituximab and cyclophosphamide (DRC) in the frontline setting. We report on the efficacy of DRC, focusing on relapsed/refractory (R/R) patients. Ibrutinib, a recently approved agent in WM demonstrated limited activity in patients with MYD88^WT genotype. Herein, we additionally report on the activity of DRC based on the MYD88^L265P mutation status. Of 100 WM patients evaluated between January 2007 and December 2014 who received DRC, 50 had R/R WM. The overall response rate (ORR) was 87%. The median progression-free survival (PFS) and time-to-next-therapy (TTNT) were 32 (95% confidence interval [CI]: 15-51) and 50 (95% CI: 35-60) months, respectively. In the previously untreated cohort (n = 50), the ORR was 96%, and the median PFS and TTNT were 34 months (95% CI: 23-not reached [NR]) and NR (95% CI: 37-NR), respectively. Twenty-five (86%) of 29 genotyped patients harbored MYD88^L265P . The response rates and outcomes were independent of MYD88 mutation status. Grade ≥3 adverse effects included neutropenia (20%), thrombocytopenia (7%) and infections (3%). Similar to the frontline setting, DRC is an effective and well-tolerated salvage regimen for WM. In contrast to ibrutinib, DRC offers a less expensive, fixed-duration option, with preliminary data suggesting efficacy independent of the patients' MYD88 status.

Scope of translational medicine in developing boron-containing compounds for therapeutics

The ubiquitousness of naturally occurring boron-containing compounds (BCCs) has led to their constant contact with humankind. Recently, many synthetic BCCs have been elaborated for a broad spectrum of purposes, especially boric, boronic and borinic acids. Although BCCs were once employed primarily as antiseptics and later as antibiotics, they have become an increasingly relevant therapeutic tool. Nevertheless, this potential of BCCs has been drastically limited due to some unfortunate intra-hospital accidents in the 1940s and 1950s. The increasing use of BCCs as insecticides, antimicrobials, and other agents is providing new insights into their role in the physiology of several living species and in the pathophysiology of humans. It is becoming clear that BCCs act through a wide range of mechanisms, as do their corresponding boron-free counterparts. When comparing BCCs and similar boron-free compounds, in many cases the former show advantages in the medical field. The current mini-review focuses on how BCCs have been developed by means of translational medicine, a process connecting biomedical research with clinical applications. This process of discovery is currently in an exponential stage.

A phase II Bayesian sequential clinical trial in advanced Waldenström macroglobulinemia patients treated with bortezomib: interest of addition of dexamethasone

In patients with advanced Waldenström macroglobulinemia (WM), overall response rate (ORR) and median progression-free survival (PFS) achieved with bortezomib alone and bortezomib rituximab combination were 27-85% and 7.9 months, and 81% and 16.4 months, respectively. We checked the role of dexamethasone in combination with bortezomib by enrolling in a phase II trial 34 patients with relapsed/refractory WM. Bortezomib (1.3 mg/m² IV D1, 4, 8, and 11 every 21 days) was used for six cycles. In non-responding patients, dexamethasone (20 mg daily for two days) was added to each infusion after the second cycle. After two cycles, the Bayes estimated ORR was 43.2 (95% Credible Interval: 28.0-59.1%) using the informative prior. Two-year survival rate was 84.0% and the median PFS 15.3 months without difference between patients treated with or without dexamethasone. We conclude that dexamethasone must be associated to bortezomib-based regimen.

BDR in newly diagnosed patients with WM: final analysis of a phase 2 study after a minimum follow-up of 6 years

BDR is a chemotherapy-free, non-stem-cell–toxic regimen associated with high response rates and long-term remissions. The long-term safety profile of BDR is favorable, with high probability of response to reintroduction of rituximab-based regimens at relapse.

Current therapy guidelines for Waldenstrom's macroglobulinaemia

Waldenstrom's macroglobulinaemia (WM) is a B-cell neoplasm in which bone marrow is infiltrated by lymphoplasmacytic cells that secrete monoclonal immunoglobulin M (IgM). More than a decade ago, specific criteria were agreed to define diagnosis and symptomatic disease requiring therapy; however, treatment recommendations change as new options emerge. Treatment decisions consider specific disease characteristics (burden of disease, IgM levels, presence of cytopenias) and patient characteristics (age, comorbidities, toxicity). Recently, the impact of specific mutations (in MYD88 and CXCR4) in response to specific therapies has been reported, and this may affect treatment decisions in the future. Chemo-immunotherapy combinations based on rituximab with cyclophosphamide/dexamethasone, bendamustine or bortezomib/dexamethasone are indicated for most patients. The BTK inhibitor ibrutinib was recently approved for patients with WM, and is a new option for selected newly diagnosed or relapsing patients. New B-cell receptor inhibitors, second-generation proteasome inhibitors and mammalian target of rapamycin inhibitors are promising; however, more data are needed from high-quality clinical trials.

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.

NF-κB dysregulation in multiple myeloma

The nuclear factor-κB (NF-κB) transcription factor family plays critical roles in the pathophysiology of hematologic neoplasias, including multiple myeloma. The current review examines the roles that this transcription factor system plays in multiple myeloma cells and the nonmalignant accessory cells of the local microenvironment; as well as the evidence indicating that a large proportion of myeloma patients harbor genomic lesions which perturb diverse genes regulating the activity of NF-κB. This article also discusses the therapeutic targeting of the NF-κB pathway using proteasome inhibitors, a pharmacological class that has become a cornerstone in the therapeutic management of myeloma; and reviews some of the future challenges and opportunities for NF-κB-related research in myeloma.

Evolution of Management and Outcomes in Waldenström Macroglobulinemia: A Population-Based Analysis

INTRODUCTION

Waldenström macroglobulinemia/lymphoplasmacytic lymphoma (WM) is a rare lymphoma affecting older patients. Its management largely relies on small phase II trials and it is unclear how their results translate into clinical practice in the community.

METHOD

We evaluated changes in the presentation, management, and survival among 2,666 Medicare beneficiaries diagnosed with WM between 1994 and 2011, using Medicare claims linked to Surveillance, Epidemiology and End Results data.

RESULTS

Prevalence of transfusions, anemia, thrombocytopenia, and neuropathy at diagnosis significantly increased over time, whereas the use of plasmapheresis was low (2.5%) and stable. The proportion of patients starting chemotherapy within 1 year of WM diagnosis increased from 39% in 1994 to 62% in 2011 (p < .0001). Treatments based on classic alkylators and purine analogs predominated in the 1990s, but were quickly replaced by rituximab-containing regimens after 2000. Rituximab monotherapy has been prescribed for >50% of patients since 2004, and combination chemoimmunotherapy for a further 30%. Most patients initiating multiagent regimens in 2012-2013 received rituximab with bortezomib or bendamustine. These changes were accompanied by significant improvements in overall and WM-related survival, but also by a significant increase in cost of chemotherapy. Mean Medicare payments for chemotherapy drugs accrued in the first year of treatment rose from $9,464 in 1994-2000 to $29,490 after 2008.

CONCLUSION

Hematologists have rapidly adopted innovative, expensive therapies for WM before completion of randomized trials. This underscores the need to assess the comparative value of such therapies in rare malignancies through a combination of clinical and observational data.

IMPLICATIONS FOR PRACTICE

Most older patients with Waldenström macroglobulinemia currently treated in the U.S. receive rituximab as monotherapy or in combination with bortezomib or bendamustine. Newly designed trials should consider control arms aligned with this prevalent real-life standard. Compared with the 1990s, patients diagnosed according to current criteria are more likely to have anemia or neuropathy, or to receive early chemotherapy, but only 2.5% require plasmapheresis at diagnosis. The incremental clinical value of newly introduced agents needs to be assessed through a combination of clinical and health services research, taking into consideration their associated survival benefits, toxicities, and associated costs of care.

Managing treatment-related peripheral neuropathy in patients with multiple myeloma

Peripheral neuropathy is one of the most important complications of multiple myeloma treatment. Neurological damage can be observed at the onset of the disease, due to the effect of monoclonal protein or radicular compression, but more often is treatment related. Vinca alkaloids in the past era, and more recently, thalidomide and bortezomib are mainly responsible. Degeneration of dorsal root ganglion is common, prevalently related to angiogenesis inhibition and cytokine modulation in the case of thalidomide and inhibition of the ubiquitin proteasome system in the case of bortezomib. Sensory neuropathy and neuropathic pain are more common; motor neuropathy and autonomic damage are less frequently observed. Neurotoxicity often affects patient's quality of life and requires dose modification or withdrawal of therapy, with a possible effect on the overall response. A prompt recognition of predisposing factors (such as diabetes mellitus, alcohol abuse, vitamin deficiencies, or viral infections) and appearance of signs and symptoms, through a periodic neurological assessment with appropriate scales, is extremely important. Effective management of treatment at the emergence of peripheral neuropathy can minimize the incidence and severity of this complication and preserve therapeutic efficacy. Dose adjustment could be necessary during treatment; moreover, gabapentin or pregabalin, tricyclic antidepressants, serotonin and norepinephrine reuptake inhibitors, carbamazepine, and opioid-type analgesics are suggested according to the pain severity. Some authors reported that patients who develop peripheral neuropathy during their multiple myeloma treatments presented a particular gene expression profile; therefore, future studies could be helpful for a better understanding of possible biological pathways underlying neurotoxicity.

Idelalisib for the treatment of non-Hodgkin lymphoma

INTRODUCTION

B-cell Non-Hodgkin lymphomas (B-NHLs) include a number of disease subtypes, each defined by the tempo of disease progression and the identity of the cancerous cell. Idelalisib is a potent, selective inhibitor of the delta isoform of phosphatidylinositol-3-kinase (PI3K), a lipid kinase whose over-activity in B-NHL drives disease progression. Idelalisib has demonstrated activity in indolent B-NHL (iB-NHL) and is approved for use as monotherapy in patients with follicular lymphoma and small lymphocytic lymphoma and in combination with rituximab in patients with chronic lymphocytic leukemia.

AREAS COVERED

Herein we review the development and pharmacology of idelalisib, its safety and efficacy in clinical studies of iB-NHL, and its potential for inclusion in future applications in iB-NHL and in combination with other therapies.

EXPERT OPINION

Idelalisib adds to the growing arsenal of iB-NHL pharmacotherapeutics and to the progression of the field toward precision agents with good efficacy and reduced toxicities. Nevertheless, idelalisib carries important risks that require careful patient counseling and monitoring. The appropriate sequencing of idelalisib with other proven treatment options in addition to its potential for combination with established or novel drugs will be borne out in ongoing and planned investigations.

Waldenstrom Macroglobulinemia: Genomic Aberrations and Treatment

Waldenström macroglobulinemia (WM) is a rare, indolent, and monoclonal immunoglobulin M-associated lymphoplasmacytic disorder with unique clinicopathologic characteristics. Over the past decade, remarkable progress has occurred on both the diagnostic and therapeutic fronts in WM. A deeper understanding of the disease biology emanates from the seminal discoveries of myeloid differentiation primary response 88 (MYD88) L265P somatic mutation in the vast majority of cases and C-X-C chemokine receptor, type 4, mutations in about a third of patients. Although WM remains an incurable malignancy, and the indications to initiate treatment are largely unchanged, the therapeutic armamentarium continues to expand. Acknowledging the paucity of high-level evidence from large randomized controlled trials, herein, we evaluate the genomic aberrations and provide a strategic framework for the management in the frontline as well as the relapsed/refractory settings of symptomatic WM.

Development of the Bruton's tyrosine kinase inhibitor ibrutinib for B cell malignancies

Ibrutinib is a first-in-class oral covalent inhibitor of Bruton's tyrosine kinase that has demonstrated clinical benefit for many patients with B cell malignancies. Positive results in initial trials led the U.S. Food and Drug Administration to grant ibrutinib three breakthrough therapy designations for mantle cell lymphoma (MCL), del17p chronic lymphocytic leukemia (CLL), and Waldenström's macroglobulinemia (WM). Ibrutinib was approved for these three cancers within 14 months of the original U.S. approval. Additionally, ibrutinib is approved for patient subsets with MCL and/or CLL in >45 other countries. Via a unique mechanism of action, ibrutinib inhibits B cell signaling pathways that regulate the survival, proliferation, adhesion, and homing of cancerous cells. This marks a paradigm shift from the conventional cytotoxic chemotherapy approach to treating B cell malignancies. Ibrutinib continues to be evaluated across a range of B cell malignancies, either as single-agent therapy or in combination with other therapies, and continues to transform the lives of these patients.

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.

The Globalization of Cooperative Groups

The National Cancer Institute (NCI)-supported adult cooperative oncology research groups (now officially Network groups) have a longstanding history of participating in international collaborations throughout the world. Most frequently, the US-based cooperative groups work reciprocally with the Canadian national adult cancer clinical trial group, NCIC CTG (previously the National Cancer Institute of Canada Clinical Trials Group). Thus, Canada is the largest contributor to cooperative groups based in the United States, and vice versa. Although international collaborations have many benefits, they are most frequently utilized to enhance patient accrual to large phase III trials originating in the United States or Canada. Within the cooperative group setting, adequate attention has not been given to the study of cancers that are unique to countries outside the United States and Canada, such as those frequently associated with infections in Latin America, Asia, and Africa. Global collaborations are limited by a number of barriers, some of which are unique to the countries involved, while others are related to financial support and to US policies that restrict drug distribution outside the United States. This article serves to detail the cooperative group experience in international research and describe how international collaboration in cancer clinical trials is a promising and important area that requires greater consideration in the future.

Ibrutinib in previously treated Waldenström's macroglobulinemia

BACKGROUND

MYD88(L265P) and CXCR4(WHIM) mutations are highly prevalent in Waldenström's macroglobulinemia. MYD88(L265P) triggers tumor-cell growth through Bruton's tyrosine kinase, a target of ibrutinib. CXCR4(WHIM) mutations confer in vitro resistance to ibrutinib.

METHODS

We performed a prospective study of ibrutinib in 63 symptomatic patients with Waldenström's macroglobulinemia who had received at least one previous treatment, and we investigated the effect of MYD88 and CXCR4 mutations on outcomes. Ibrutinib at a daily dose of 420 mg was administered orally until disease progression or the development of unacceptable toxic effects.

RESULTS

After the patients received ibrutinib, median serum IgM levels decreased from 3520 mg per deciliter to 880 mg per deciliter, median hemoglobin levels increased from 10.5 g per deciliter to 13.8 g per deciliter, and bone marrow involvement decreased from 60% to 25% (P<0.01 for all comparisons). The median time to at least a minor response was 4 weeks. The overall response rate was 90.5%, and the major response rate was 73.0%; these rates were highest among patients with MYD88(L265P)CXCR4(WT) (with WT indicating wild-type) (100% overall response rate and 91.2% major response rate), followed by patients with MYD88(L265P)CXCR4(WHIM) (85.7% and 61.9%, respectively) and patients with MYD88(WT)CXCR4(WT) (71.4% and 28.6%). The estimated 2-year progression-free and overall survival rates among all patients were 69.1% and 95.2%, respectively. Treatment-related toxic effects of grade 2 or higher included neutropenia (in 22% of the patients) and thrombocytopenia (in 14%), which were more common in heavily pretreated patients; postprocedural bleeding (in 3%); epistaxis associated with the use of fish-oil supplements (in 3%); and atrial fibrillation associated with a history of arrhythmia (5%).

CONCLUSIONS

Ibrutinib was highly active, associated with durable responses, and safe in pretreated patients with Waldenström's macroglobulinemia. MYD88 and CXCR4 mutation status affected responses to this drug. (Funded by Pharmacyclics and others; ClinicalTrials.gov number, NCT01614821.).

Waldenström macroglobulinemia: What a hematologist needs to know

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