Trends in Incidence and Mortality of Waldenström Macroglobulinemia: A Population-Based Study

Bruton Tyrosine Kinase Inhibition: an Effective Strategy to Manage Waldenström Macroglobulinemia

PURPOSE OF REVIEW

The treatment of Waldenström macroglobulinemia (WM) has evolved over the past decade. With the seminal discoveries of MYD88 and CXCR warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) mutations in WM cells, our understanding of the disease biology and treatment has improved. The development of a new class of agents, Bruton tyrosine kinase inhibitors (BTKi), has substantially impacted the treatment paradigm of WM. Herein, we review the current and emerging BTKi and the evidence for their use in WM.

RECENT FINDINGS

Clinical trials have established the role of covalent BTKi in the treatment of WM. Their efficacy is compromised among patients who harbor CXCR4WHIM mutation or MYD88WT genotype. The development of BTKC481 mutation-mediated resistance to covalent BTKi may lead to disease refractoriness. Novel, non-covalent, next-generation BTKi are emerging, and preliminary results of the early phase clinical trials show promising activity in WM, even among patients refractory to a covalent BTKi. Covalent BTK inhibitors have demonstrated meaningful outcomes in treatment-naïve (TN) and relapsed refractory (R/R) WM, particularly among those harboring the MYD88L265P mutation. The next-generation BTKi demonstrate improved selectivity, resulting in a more favorable toxicity profile. In WM, BTKi are administered until progression or the development of intolerable toxicity. Consequently, the potential for acquired resistance, the emergence of cumulative toxicities, and treatment-related financial burden are critical challenges associated with the continuous therapy approach. By circumventing BTK C481 mutations that alter the binding site to covalent BTKi, the non-covalent BTKi serve as alternative agents in the event of acquired resistance. Head-to-head comparative trials with the conventional chemoimmunotherapies are lacking. The findings of the RAINBOW trial (NCT046152), comparing the dexamethasone, rituximab, and cyclophosphamide (DRC) regimen to the first-generation, ibrutinib are awaited, but more studies are needed to draw definitive conclusions on the comparative efficacy of chemoimmunotherapy and BTKi. Complete response is elusive with BTKi, and combination regimens to improve upon the efficacy and limit the treatment duration are also under evaluation in WM.

Management of Waldenström Macroglobulinemia in Limited-Resource Settings

Waldenström macroglobulinemia (WM) is a rare, indolent, and currently incurable B-cell neoplasm characterized by monoclonal immunoglobulin M gammopathy, frequent nodal involvement, and lymphoplasmacytic infiltration of the bone marrow. The clinical pattern at diagnosis is similar to that reported in developed countries but, unfortunately, the tools for a complete diagnosis and access to novel therapies are suboptimal. Older drugs such as bendamustine, cyclophosphamide, and chlorambucil may still play a role in treating WM. Prospective studies in resource-limited regions are required to further evaluate these essential aspects of the disease. In this document, we issue recommendations based on our local reality.

Survival trends in young patients with Waldenström macroglobulinemia: Over five decades of experience

Waldenström macroglobulinemia (WM) is a rare, indolent lymphoma, that predominately affects the elderly. We report the outcomes of young WM patients, evaluated over five decades, compared to their older counterparts, matched for the time of diagnosis. Between January 1, 1960 and October 31, 2013, 140 (11.8%) WM patients were ≤50 years of age at diagnosis in our database, and their estimated 10-year overall survival (OS) was 74%, with death attributable to WM in a higher proportion of patients compared to their older (≥65 years) counterparts (91% vs. 58%, p = .0001). Young patients were grouped into three cohorts based on the timing of the initiation of therapy: Group 1 (1960-1977, n = 12), Group 2 (1978-1995, n = 48), and Group 3 (1996-2013, n = 74). Among young patients, there was no disease-specific survival (DSS) difference across the three periods, [median DSS at 13 years (95% CI 5-23), 16 years (95% CI 14-22), and 15 years (95% CI 10-NR; p = .41), respectively]. However, DSS for the older cohort incrementally improved (Group 1, median 5.2 years, Group 2: 9.6 years, Group 3: 12 years; p = .05) over these periods. The estimated average years-of-life lost for the young cohort was 11.2 years from diagnosis, based on the expected survival for a normal age- and sex-matched population. Despite a protracted disease course, nearly all young patients succumb to their disease. In contrast to the improved survival of the elderly patient population, the evolving treatment strategies in WM have not impacted the outcome of young patients; however, the impact of Bruton tyrosine kinase inhibitors on this unique patient population remains to be determined.

Coming of Age for BTK Inhibitor Therapy: A Review of Zanubrutinib in Waldenström Macroglobulinemia

Waldenström macroglobulinemia (WM) is a rare form of non-Hodgkin B-cell lymphoma with a variable clinical presentation that can impact a patient’s quality of life by causing anemia, peripheral neuropathy, serum hyperviscosity, extramedullary disease, and other symptoms. There are several safe and effective treatment regimens for patients with WM, and the choice of therapy should be made in a personalized fashion considering the patient’s symptoms, comorbidities, and genomic profile. Bruton tyrosine kinase (BTK) inhibitors are a new option to treat patients with WM. Zanubrutinib is a next-generation covalent BTK inhibitor designed to have fewer off-target effects than previous BTK inhibitors. This review summarizes the pharmacokinetic and pharmacodynamic properties of zanubrutinib as well as safety and efficacy findings. Then, it explores the health economic and outcomes research associated with the costs of treating patients with WM and the reasons why zanubrutinib may be a more cost-effective treatment option compared with ibrutinib, a first-generation BTK inhibitor. Future directions for the treatment of WM focus on the use of zanubrutinib in combination therapy. Combinations based on effective ibrutinib or acalabrutinib treatments may be effectively applied with zanubrutinib given the similar mechanism of action for these BTK inhibitors. Combination therapies could also help prevent the development of disease resistance, minimize toxicity, and support treatment regimens of finite duration.

Waldenstrom Macroglobulinemia: Tailoring Therapy for the Individual

With the introduction of multiple new effective therapeutic options for the treatment of macroglobulinemia, a structured approach to management of this rare lymphoma is currently needed. A review of phase II and III treatment trials over the past 20 years was performed, and high-quality trials are summarized in this manuscript. Because of the lack of large prospective trials comparing different classes of therapy, a uniform recommendation applicable to all patients cannot be made, and the approach must be individualized incorporating patient preferences, comorbidities, and the range of therapeutic toxicities. Therapeutic options for patients with newly diagnosed and previously treated macroglobulinemia are presented on the basis of the best available evidence in the literature.

Treatment and Survival Outcomes of Waldenstrom Macroglobulinemia in Latin American Patients: A Multinational Retrospective Cohort Study

Waldenstrom Macroglobulinemia (WM) is a rare lymphoma with distinct clinical features, and data from Latin American patients are lacking. Therefore, we aim to investigate the clinical, therapy, and outcome patterns of WM in Latin America.

Waldenstrom Macroglobulinemia (WM) is a rare lymphoma with distinct clinical features. Data from Latin American WM patients are lacking. In this article, we report, for the first time, the results of a retrospective analysis focused on the clinical, therapy, and outcome patterns of WM in Latin America. Moreover, we have validated the IPSSWM score as a prognostic factor for mortality and disease progression. Despite the limitations we acknowledge, this is the first study to provide novel real-world data on WM in Latin America.

Dutch Physician's Perspectives on Diagnosis and Treatment of Waldenström's Macroglobulinemia Before and After the Implementation of a National Guideline

Waldenström's macroglobulinemia (WM), a rare low-grade B-cell non-Hodgkin lymphoma (NHL), has a distinct clinical presentation and different treatment-related side effects compared with other NHL. Currently, a wide variety of therapeutic agents are available for the treatment of WM but there is no consensus on optimal treatment in first line and/or at relapse. The aim of this survey was to evaluate the current knowledge and perspectives of hematologists on diagnosis and treatment of WM. Also, we compare these results to a similar survey done before the publication of the first Dutch national guideline, in order to evaluate the impact of the implementation of a national guideline. A link to an online survey was sent out to all registered hematologists and hemato-oncologists in the Netherlands with the request to participate. The survey contained questions regarding the preferred diagnostic and treatment methods in patients with WM as well as treatment goals. We also compared physicians preferred treatment goals to those of patients (as studied in a recent nationwide patient questionnaire). Ninety-five responses (30% response rate) were obtained, out of which 82 (86%) surveys were complete. The respondents most commonly used dexamethasone-rituximab-cyclophosphamide as first-line treatment. For second-line treatment, bendamustine with rituximab and ibrutinib monotherapy were the most frequently applied. Compared with the initial survey, serum IgM M-protein was determined in all cases, MYD88 mutation analysis was currently widely implemented, prevention of an IgM "flare" was uniformly managed by the respondents and use of rituximab-cyclophosphamide-vincristine-prednisone was entirely abandoned. Physicians differed somewhat from patients with regard to most important treatment goals. The approach to diagnostic methods and treatment options in WM was more consistent with international guidelines and was more homogeneous after implementation of the national guideline. These data indicate an increase in knowledge on WM diagnosis and treatment. This may have resulted from implementation of a local guideline or the global rise in awareness and attention for WM.

The Use of Bruton Tyrosine Kinase Inhibitors in Waldenström’s Macroglobulinemia

The use of Bruton Tyrosine Kinase (BTK) inhibitors in Waldenström’s Macroglobulinemia (WM) is evolving. Ibrutinib, a first-generation BTK inhibitor, is currently approved for use in frontline and relapsed/refractory disease. Second-generation BTK inhibitors are being used and studied to improve clinical outcomes and/or safety profile. Zanubrutinib, one such second-generation inhibitor, was recently approved in treatment-naive and refractory/relapsed patients. Here, we review the use of BTK inhibitors in WM in front-line and refractory or relapsed settings. We also highlight common adverse events, the emergence of BTK inhibitors resistance, and future directions of their use.

An Extended Prognostic Index of the ISSWM Score Based on Thyroid Complications in Waldenström Macroglobulinemia/Lymphoplasmacytoid Lymphoma

Waldenström macroglobulinemia/lymphoplasmacytoid lymphoma (WM/LPL) is a rare lymphoproliferative neoplasm characterized by clonally related lymphocytes, lymphoplasmacytic cells, and plasma cell proliferation. WM/LPL patients commonly present with elevated immunoglobulin, predominantly immunoglobulin M (IgM). Previous studies reported that thyroid dysfunction was associated with the development and progression of solid tumors. However, only limited information is available on the correlation between thyroid complications and lymphoid malignancies. The aim of our study was to explore the prognostic significance of thyroid complications in WM/LPL. Herein, 13.3% of WM/LPL patients were diagnosed with thyroid complications, which were significantly associated with unfavorable progression-free survival (PFS), overall survival (OS), and adverse treatment response. Co-existing thyroid disease was significantly related to alleviated serum IgM levels, providing an answer to practical problems. Furthermore, the presence of thyroid complications was identified as an independent prognostic indicator for PFS in WM/LPL. Incorporating the ISSWM score with thyroid complications was superior to ISSWM alone in risk stratification and prognostic prediction. Furthermore, subgroup analyses of WM/LPL patients revealed that subclinical hypothyroidism predicted undesirable outcomes at the early stage. These results were also supported by independent microarray dataset analyses. In conclusion, the primary strength of this study is that it provides robust real-world evidence on the prognostic role of thyroid complications, highlighting further clinical concerns in the management of WM/LPL patients.

Treatment paradigm in Waldenström macroglobulinemia: frontline therapy and beyond

Waldenström macroglobulinemia (WM) is an indolent lymphoplasmacytic lymphoma. Recent strides made in the genomic profiling of patients with WM have led to the identification of many novel therapeutic targets. Patients with WM can present with asymptomatic disease and not all patients require treatment. When criteria for initiating systemic therapy are met, the choice of therapy depends on the tumor genotype (MYD88 and CXCR4 mutation status), patient preference (fixed versus continuous duration therapy, oral versus intravenous route, cost), associated medical comorbidities, and adverse effect profile of the treatment. In the absence of head-to-head comparison between chemoimmunotherapy and Bruton’s tyrosine kinase inhibitors in otherwise fit patients with a MYD88^L265P mutation, our preference is fixed duration therapy with four to six cycles of chemoimmunotherapy with bendamustine–rituximab. In this review, we discuss the role of MYD88 and CXCR4 mutation in treatment selection, and current data for frontline and salvage treatment options in patients with WM.

The Use of Bruton Tyrosine Kinase Inhibitors in Waldenström’s Macroglobulinemia

Waldenström’s macroglobulinemia (WM) remains an incurable malignancy. However, a number of treatment options exist for patients with WM, including alkylating agents, anti-CD20 monoclonal antibodies, and small molecule inhibitors such as proteasome inhibitors and Bruton tyrosine kinase inhibitors (BTKi). The focus of this review is to highlight the role of BTKi in the management of WM. The first BTKi to receive US Food and Drug Administration approval for WM was ibrutinib. Ibrutinib has been extensively studied in both treatment-naïve WM patients and in those with relapsed/refractory disease. The next BTKi approved for use was zanubrutinib, and prospective data for acalabrutinib and tirabrutinib have also recently been published. Efficacy data for BTKi will be discussed, as well as the differences in their adverse event profiles.

Two-year outcomes of tirabrutinib monotherapy in Waldenström's macroglobulinemia

The phase II study of tirabrutinib monotherapy at a daily dose of 480 mg under fasted conditions for treatment-naïve and relapsed/refractory Waldenström's macroglobulinemia (ONO-4059-05 study) demonstrated a promising efficacy and tolerable safety profile. We conducted an unplanned analysis with a median follow-up of 24.8 months to update the efficacy and safety results and to report patient-reported quality of life. Of 27 enrolled patients, 22 patients continued receiving the study drug. The major response assessed by an independent review committee was observed in 25 patients (93%), including 1 and 5 patients who newly achieved complete response and very good partial response, respectively, after the primary analysis. The progression-free and overall survival rates at 24 months were 92.6% and 100%, respectively. Serum IgM levels in all patients except one declined and were maintained at low levels although transient increases occurred after temporal interruption of the study drug. The disease-related symptoms including recurrent fever and hyperviscosity mostly disappeared. Health-related quality of life, assessed by cancer-specific questionnaires, was mostly maintained. Grade 3-4 neutropenia, lymphopenia, and leukopenia were newly recognized in three, two, and one patient, respectively. Grade 3 treatment-related hypertriglyceridemia was also recognized. Nine patients experienced grade 1-2 bleeding events (33%), one patient experienced grade 2 treatment-related atrial fibrillation, and one patient experienced grade 1 treatment-related hypertension. Treatment-related skin adverse events were observed in 14 patients (52%). Taken together, tirabrutinib has durable efficacy with an acceptable safety profile for treatment-naïve and refractory/relapsed Waldenström's macroglobulinemia.

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.

Primary therapy and relative survival in patients with lymphoplasmacytic lymphoma/Waldenström macroglobulinaemia: a population-based study in the Netherlands, 1989-2018

It is unclear how treatment advances impacted the population‐level survival of patients with lymphoplasmacytic lymphoma/Waldenström macroglobulinaemia (LPL/WM). Therefore, we assessed trends in first‐line therapy and relative survival (RS) among patients with LPL/WM diagnosed in the Netherlands between 1989 and 2018 (N = 6232; median age, 70 years; 61% males) using data from the nationwide Netherlands Cancer Registry. Patients were grouped into three age groups (<65, 66–75 and >75 years) and four calendar periods. Overall, treatment with anti‐neoplastic agents within 1 year post‐diagnosis gradually decreased over time, following a broader application of an initial watch‐and‐wait approach. Approximately 40% of patients received anti‐neoplastic therapy during 2011–2018. Furthermore, use of chemotherapy alone decreased over time, following an increased application of chemoimmunotherapy. Detailed data among 1596 patients diagnosed during 2014–2018 revealed that dexamethasone‐rituximab‐cyclophosphamide was the most frequently applied regimen; its use increased from 14% to 39% between 2014 and 2018. The 5‐year RS increased significantly over time, particularly since the introduction of rituximab in the early–mid 2000s. The 5‐year RS during 1989–1995 was 75%, 65%, and 46% across the age groups compared to 93%, 85%, and 79% during 2011–2018. However, the survival improvement was less pronounced after 2011. Collectively, the impressive survival improvement may be accounted for by broader application of rituximab‐containing therapy. The lack of survival improvement in the post‐rituximab era warrants studies across multiple lines of therapy to further improve survival in LPL/WM.