Treatment recommendations from the Eighth International Workshop on Waldenström's Macroglobulinemia

Pathophysiology and Treatments of Complications of Waldenström's Macroglobulinemia

Waldenstrom's macroglobulinemia (WM) or lymphoplasmacytic lymphoma is a B-cell malignancy characterized by lymphoplasmacytic cells in the bone marrow that secrete high amounts of immunoglobulin (Ig) M. The large pentameric structure of IgM leads to a variety of unique complications in WM, such as hyperviscosity syndrome, cryoglobulinemia and sensory neuropathy. Furthermore, malignant cells can infiltrate the central nervous system and lead to a variety of neurological complications, also known as Bing Neel Syndrome. Because of the unique pathophysiology of WM and these complications, their diagnostic work up and treatment regimens vary greatly. Given the rarity of the disease and their complications, there are little to no randomized controlled trials regarding treatments of these complications and, therefore, suggested treatment regimens are usually based on observational studies. In this case series, we will present three cases of WM, each with their own unique complication, and discuss the pathophysiology along with current and future treatment options for each of the complications presented.

Different extramedullary disease shown in chemokine receptor 4 targeted PET/CT with [ 68 Ga]Ga-pentixafor in patients with Waldenström macroglobulinemia and smoldering disease

INTRODUCTION

It is important to distinguish Waldenström macroglobulinemia from smoldering Waldenström macroglobulinemia (sWM), because only patients with Waldenström macroglobulinemia require treatment, however the distinction can be clinically complex. The aim of this study is to investigate whether [ 68 Ga]Ga-pentixafor PET/CT shows different characteristics in sWM and Waldenström macroglobulinemia patients and therefore can help to differentiate Waldenström macroglobulinemia and sWM.

RESULTS

Thirty-seven patients with newly diagnosed Waldenström macroglobulinemia and 11 sWM patients were analyzed [35 men and 13 women; 64.3 ± 10.7 (range, 29-87) years old]. The SUV max of bone marrow disease, lymph nodes, and other extramedullary diseases on [ 68 Ga]Ga-pentixafor were significantly higher than those on 2-[ 18 F]FDG PET/CT ( P  < 0.05). On [ 68 Ga]Ga-pentixafor PET/CT, patients with Waldenström macroglobulinemia had more lymph node regions involved, significantly higher incidence of involvement in more than three lymph node regions, larger nodal disease, and higher incidence of other extramedullary disease when compared with sWM patients ( P  < 0.05). Waldenström macroglobulinemia patients showed significantly higher total lesions uptake, total lesion volume, and SUV max of extramedullary disease than sWM patients did ( P  < 0.05). None of the visual or semiquantitative indexes in 2-[ 18 F]FDG PET/CT showed significant difference between Waldenström macroglobulinemia and sWM patients.

CONCLUSION

[ 68 Ga]Ga-pentixafor PET/CT had better diagnostic performance than 2-[ 18 F]FDG PET/CT in Waldenström macroglobulinemia. Patients with Waldenström macroglobulinemia presented with more extensive extramedullary disease shown in [ 68 Ga]Ga-pentixafor PET/CT than sWM patients did.

Sequential treatment escalation improves survival in patients with Waldenstrom macroglobulinemia

Waldenstrom macroglobulinemia (WM) is a type of incurable, indolent B-cell lymphoma that is prone to relapse. Over time, treatment strategies have progressed from cytotoxic drugs to rituximab (R)- or bortezomib (V)-based regimens, and have now entered into an era of Bruton tyrosine kinase inhibitor (BTKi)-based regimens. However, the optimal treatment for the relapsed patients is still unclear. Herein, we analyzed the outcomes of the first- and second-line therapies in 377 patients with WM to illustrate the optimal choices for second-line therapy. After a median follow-up of 45.4 months, 89 patients received second-line therapy, and 53 patients were evaluated for response. The major response rates (MRR) of first- and second-line treatment were 65.1% and 67.9% (P = 0.678). The median progression-free survival (PFS) for the second-line therapy (PFS2) was shorter than that for the first-line therapy (PFS1) (56.3 vs 40.7 months, P = 0.03). However, PFS2 in targeted drugs group (R-/V-/BTKi-based regimens) was comparable to PFS1 (60.7 months vs 44.7 months, respectively, P = 0.21). Regarding second-line therapy, patients who underwent sequential treatment escalation-such as transitioning from cytotoxic drugs to R-/V-/BTKi-based regimens or from R-/V-based to BTKi-based regimens (escalation group) -had higher MRR (80.6% vs 47.1%, respectively, P = 0.023) and longer PFS2 (50.4 vs 23.5 months, respectively, P < 0.001) compared to the non-escalation group. Patients in the escalation group also had longer post-relapse overall survival compared with the non-escalation group (median, 50.4 vs 23.5 months, respectively, P = 0.039). Our findings indicate that sequential treatment escalation may improve the survival of patients with WM.

Efficacy and safety of front-line treatment regimens for Waldenstrom macroglobulinaemia: a systematic review and meta-analysis

Rituximab-based chemo-immunotherapy is currently the standard first-line treatment for Waldenstrom macroglobulinaemia (WM), while ibrutinib has emerged as an alternative. In the absence of randomised trials (RCTs) comparing these regimens, the optimal first-line treatment for WM remains uncertain. In this systematic review and meta-analysis, we sought to assess the efficacy and safety of first-line treatment regimens for WM. We searched key databases from January 2007 to March 2023, including phase II and III trials, including treatment-naïve WM patients treated with rituximab-based regimens or ibrutinib. Response rates, progression-free survival (PFS), overall survival (OS), and toxicities were evaluated. Four phase III and seven phase II trials were included among 736 unique records. Pooled response rates from all comparative and non-comparative trials were 46%, 33% and 26% for bendamustine rituximab (BR), bortezomib-dexamethasone, cyclophosphamide, rituximab (BDRC) and ibrutinib rituximab (IR), respectively. Two-year pooled PFS was 89%, 81% and 82% with BR, BDRC and IR, respectively. Neuropathy was more frequent with bortezomib, while haematologic and cardiac toxicities were more common with chemo-immunotherapy and ibrutinib-based regimens respectively. Our findings suggest that BR yields higher response rates than bortezomib or ibrutinib-based combinations. RCTs comparing BR against emerging therapies, including novel Bruton Tyrosine Kinase Inhibitors, are warranted.

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.

Biomarkers of Progression and Risk Stratification in Asymptomatic Waldenström Macroglobulinemia

Waldenström macroglobulinemia is an indolent IgM-secreting B-cell lymphoplasmacytic lymphoma that is preceded by an asymptomatic stage. Clinical and molecular features have been used in risk models to predict progression rates in different asymptomatic subgroups. Risk models used both disease-specific and nonspecific biomarkers for asymptomatic patients. Recently, models that incorporate continuous variables rather than distinct cutoffs have emerged to more accurately predict the risk of progression. Integrating genetic alterations to the clinical models is a promising approach that could improve risk stratification and management of asymptomatic patients.

Bendamustine plus rituximab for the treatment of Waldenström Macroglobulinemia: Patient outcomes and impact of bendamustine dosing

Bendamustine and rituximab (BR) therapy is commonly used in the treatment of Waldenström Macroglobulinemia (WM). The impact dose of Bendamustine dose on response and survival outcomes is not well-established, and the impact of its use in different treatment settings is not clear. We aimed to report response rates and survival outcomes following BR, and clarify the impact of depth of response and bendamustine dose on survival. A total of 250 WM patients treated with BR in the frontline or relapsed settings were included in this multicenter, retrospective cohort analysis. Rates of partial response (PR) or better differed significantly between the frontline and relapsed cohorts (91.4% vs 73.9%, respectively; p < 0.001). Depth of response impacted survival outcomes: two-year predicted PFS rates after achieving CR/VGPR vs PR were 96% versus 82%, respectively (p = 0.002). Total bendamustine dose was predictive of PFS: in the frontline setting, PFS was superior in the group receiving ≥1000 mg/m² compared with those receiving 800-999 mg/m² (p = 0.04). In the relapsed cohort, those who received doses of <600 mg/m² had poorer PFS outcomes compared with those who received ≥600 mg/m² (p = 0.02). Attaining CR/VGPR following BR results in superior survival, and total bendamustine dose significantly impacts response and survival outcomes, in both frontline and relapsed settings.

The epidemiology of Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is a rare subtype of non-Hodgkin lymphoma characterized by the presence of lymphoplasmacytic lymphoma (LPL) in the bone marrow accompanied by a monoclonal immunoglobulin type M (IgM) in the serum. WM was first described only 80 years ago and became reportable in the US as a malignancy in 1988. Very little systematic research was conducted prior to 2000 to characterize incidence, clinical characteristics, risk factors or diagnostic and prognostic criteria, and there were essentially no WM-specific clinical interventional trials. Since the inaugural meeting of the International Workshop in Waldenström's Macroglobulinemia (IWWM) in 2000, WM has become the focus of a steadily increasing and productive body of research, engaging a growing number of investigators throughout the world. This introductory overview provides summary of the current understanding of the epidemiology of WM/LPL as a backdrop for a series of consensus panel recommendations arising from research presented at the 11th IWWM.

Bruton tyrosine kinase inhibitors in the management of Waldenström macroglobulinemia

Bruton tyrosine kinase (BTK) inhibitors have taken a central role in the management of patients with Waldenström macroglobulinemia and are the only agents approved by the Food and Drug Administration (FDA) to treat these patients. Although associated with high rates of durable responses, unmet needs with BTK inhibitor therapy include indefinite duration therapy, high cost, scarcity of complete responses, and lower rates and shorter duration of response in patients with CXCR4 mutations. Herein, we review the data supporting the use of covalent BTK inhibitors, selected management issues, clinical trials with covalent BTK inhibitor combination regimens, and up-and-coming non-covalent BTK inhibitors.

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.

First-Line Treatment of Waldenström’s Macroglobulinaemia: Considerations Based on the Dutch National Guideline

Waldenström macroglobulinemia (WM) is a rare B-cell Non-Hodgkin Lymphoma. There are only few prospective randomized clinical trials to guide treatment recommendations and there is no international consensus on a preferred first line treatment approach. In the recently revised Dutch guideline for WM, we describe recommendations for practice based as much as possible on the known data. Here, we summarize the considerations for first-line treatment based on these Dutch guidelines. Available evidence is summarized, including efficacy and toxicity data. Combinations of Rituximab with chemotherapy, proteasome inhibition or BTK-inhibition are all valid first line treatment options. The Dutch WM working group considers Dexamethasone/Rituximab/Cylofosfamide (DRC) a suitable first-line treatment for many WM patients, given the efficacy, the relatively mild toxicity profile and the extensive experience with this regimen. However, the long-term toxicities of DRC are unclear and need further clarification. Other regimens such as R-bendamustine, R-Bortezomib-dexamethason are also effective options, however with specific toxicities. BTK-inhibitors are not a preferred option in first line for most patients in the Dutch WM guidelines because of the need for longterm treatment and toxicities. Based on patient preferences research, future clinical trials should focus on effective fixed-duration regimens with non-cytotoxic therapies that have a favorable toxicity profile. Further development of (combinations with) BCL-2 inhibititors, novel proteasome inhibitors and BTK-inhibition could be interesting. In addition T-cell-directed treatments including bispecific antibodies as a monotherapy or combined with other novel agents deserve further study in WM.

Should Patients with Waldenström Macroglobulinemia Receive a BTK Inhibitor as Frontline Therapy?

Waldenström Macroglobulinemia (WM) is a rare indolent lymphoma with heterogeneous clinical presentation. As there are no randomised trials suggesting the best treatment option in treatment-naive patients, guidelines suggest either rituximab-combining regimens or BTK-inhibitors (BTKi) as feasible alternatives. Several factors play in the decision-making process: patients’ age and fitness, disease characteristics and genotype. Chemoimmunotherapy (CIT) represents a fixed-duration, less expensive and effective option, able to achieve prolonged time-to-next treatment even in patients with unfavourable genotypes. Immunosuppression and treatment-related second cancers may represent serious concerns. Proteasome-inhibitor-based regimens are effective with rapid disease control, although bortezomib-related neuropathy discourages the choice of these agents and treatment schedules may not be easily manageable in the elderly. BTKi have demonstrated high rates of response and prolonged survival together with the convenience of an oral administration and limited cytopenias. However, outcomes are impacted by genotype and some concerns remain, in particular the continuous drug exposure that may result in extra-haematological complications and drug resistance. Although next-generation BTKi have improved treatment tolerance, the question whether BTKi should be offered as frontline therapy to every patient is still debated. Giving fixed-duration schedule, prolonged time-to-next treatment and outcomes independent of genotype, CIT is still our preferred choice in WM. However, BTKi remain a valuable option in frail patients unsuitable for CIT.

The Spectrum of Ocular Manifestations in Patients with Waldenström's Macroglobulinemia

PURPOSE

To investigate the ocular manifestations in 91 Waldenström's macroglobulinemia (WM) patients.

METHODS

Retrospective, cross-sectional, observational analysis.

RESULTS

Ocular impairments, detected in 19 patients, included flame-shaped hemorrhages, venous sausaging, papilledema, macular detachments, or central retinal vein occlusion in 16 patients; paraproteinemic keratopathy in 2; and a CANOMAD syndrome in 1. Best-corrected visual acuity was ≥0.5 logMAR units in 11 of 38 eyes. Intraocular pressure was increased in seven eyes. Genetic analysis in seven patients showed a mutation in the MYD88 gene in six patients and a nonsense mutation in the CXCR4 gene in five patients. Plasmapheresis followed by chemotherapy with or without the addition of rituximab resulted in improvement or normalization of the ophthalmological findings in 15 patients.

CONCLUSION

The ocular manifestations of WM are protean and potentially sight threatening. Recent advances in genomic profiling and chemotherapy have remarkably improved the hematological and ophthalmological outcomes of these patients.

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.

Co-Binding of JQ1 and Venetoclax Exhibited Synergetic Inhibitory Effect for Cancer Therapy; Potential Line of Treatment for the Waldenström Macroglobulinemia Lymphoma

In recent times, the development of combination therapy has been a focal point in drug discovery. This article explores the potential synergistic effect of co-administration of Bcl2 inhibitor Venetoclax and BET inhibitor JQ1. We envisioned that the 'dual-site'-binding of Bcl2 has significant prospects and paves the way for the next round of rational design of potent Waldenström macroglobulinemia (WM) therapy. The preferential binding mechanisms of the multi-catalytic sites of the Bcl2 enzyme have been a subject of debate in the literature. This study conducted a systematic procedure to explore the preferred binding modes and the structural effects of co-binding at each catalytic active site. Interestingly, a mutual enhanced binding effect was observed - Venetoclax increased the binding affinity of JQ1 by 11.5 %, while JQ1 boosted the binding affinity of Venetoclax by 16.3 % when compared with individual inhibition of each drug. This synergistic binding effect has significantly increased protein stability, with substantial correlated movements and multiple van der Waals interactions. The structural and thermodynamic insights unveiled in this report would assist the future design of improved combined therapy against WM.

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.

Inflammatory Waldenström's macroglobulinaemia: A French monocentric retrospective study of 67 patients

Waldenström's macroglobulinaemia (WM) is a B-cell neoplasm resulting from bone marrow lymphoplasmacytic infiltration and monoclonal IgM secretion. Some patients present concomitant inflammatory syndrome attributed to the disease activity; we named this syndrome inflammatory WM (IWM). We retrospectively analysed all WM patients seen in a single tertiary referral centre from January 2007 to May 2021, and after excluding aetiologies for the inflammatory syndrome using a pertinent blood workup, including C-reactive protein (CRP), and imaging, we identified 67 (28%) IWM, 166 (68%) non-IWM, and nine (4%) WM with inflammatory syndrome of unknown origin. At treatment initiation, IWM patients had more severe anaemia (median Hb 90 vs 99 g/l; p < 0.01), higher platelet count (median 245 vs 196 × 109/l; p < 0.01) and comparable serum IgM level (median 24.9 vs 23.0 g/l; p = 0.28). A positive correlation was found between inflammatory and haematological responses (minimal response or better) (odds ratio 32.08; 95% confidence interval 8.80-98.03; p < 0.001). Overall survivals (OS) were similar (median OS: 17 vs 20 years; p = 0.11) but time to next treatment (TNT) was significantly shorter for IWM (TNT1: 1.6 vs 4.8 years, p < 0.0001). IWM mostly shared the same presentation and outcome as WM without inflammatory syndrome.

Does early disease progression predicts survival after first line-treatment of Waldenström macroglobulinemia?

In symptomatic Waldenström macroglobulinemia (sWM) patients, prognosis is assessed with the international prognostic scoring system (IPSSWM). In follicular lymphoma and other B‐cell and T‐cell lymphomas, disease progression within 24 months (POD24) or (in patients without POD24) after 24 months has been proposed as the start date for stratifying subsequent survival. In the present report, we assessed in a large series of 472 sWM patients, the prognostic value of this new dynamic endpoint already reported in many other lymphomas subtypes. The 3 year subsequent survival for patients with POD24 was 75% and 93% for patients without POD24. In sWM patients, departure from the proportional hazards assumption complicated this analysis. In patients without POD24, the median subsequent progression‐free survival time of 43 months accounted for favorable outcome, whereas survival after progression was not influenced by the time to progression. In addition, sensitivity analysis showed that the baseline IPSSWM score also influenced survival after POD24. In sWM patients, we conclude that the apparent difference in survival after POD24 or the 24 months time‐point (in patients without POD24) is mainly explained by the prolonged subsequent progression free survival of latter patients. Indeed, the mortality after progression is not influenced by the time to this event.

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.

Hematological Malignancies and the Kidney

The incidence of hematologic malignancies is on the rise worldwide. Kidney disease is ubiquitous in patients with hematologic malignancies, encompassing a wide spectrum of disorders involving each kidney compartment, including the vasculature, tubules, interstitium, and glomerulus, and there is significant overlap of kidney involvement with each hematologic malignancy. Vascular disorders include both microvascular and macrovascular damage, via thrombotic microangiopathy, hyperleukocytosis, hyperviscosity, and cryoglobulinemia. The tubulointerstitial compartment may be affected by prerenal azotemia and acute tubular injury, but malignant infiltration, tumor lysis syndrome, extramedullary hematopoiesis, cast nephropathy, granulomatous interstitial nephritis, and lysozymuria should be considered in certain populations. Obstructive uropathy may occur due to nephrolithiasis or retroperitoneal fibrosis. Glomerular disorders, including membranoproliferative, membranous, minimal change, and focal segmental glomerulosclerosis, can rarely occur. By understanding how each compartment may be affected, care can best be optimized for these patients. In this review, we summarize the widely varied etiologies of kidney diseases stratified by kidney compartment and hematologic malignancy, focusing on demographics, pathology, pathophysiology, mechanism, and outcomes. We conclude with common electrolyte abnormalities associated with hematologic malignancies.

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.

Successful treatment with bortezomib for refractory fever associated with myelodysplastic syndrome with underlying lymphoplasmacytic lymphoma

We report a case of fever of unknown origin in a patient with MDS associated with IgM-MGUS. The patient was positive for MYD88 mutation, and chemotherapy for LPL/WM improved the fever. Analysis of MYD88 and the effect of chemotherapy on LPL/WM finally revealed the latent LPL/WM in this case.

Semi-quantitative measurements of chemokine receptor 4-targeted 68Ga-pentixafor PET/CT in response assessment of Waldenström macroglobulinemia/lymphoplasmacytic lymphoma

Purpose

⁶⁸Ga-pentixafor PET/CT was reported to have a high sensitivity in detecting tumor involvement of Waldenström macroglobulinemia/lymphoplasmacytic lymphoma (WM/LPL) in our previous study. We aimed to further investigate the semi-quantitative measurements of ⁶⁸Ga-pentixafor PET/CT in response assessment in WM/LPL.

Methods

Fifteen patients with WM/LPL were recruited in a prospective cohort study and underwent both ⁶⁸Ga-pentixafor and ¹⁸F-FDG PET/CT at baseline and post-treatment. PET/CT-based responses were analyzed with semi-quantitative assessments of metabolic tumor volume (MTV) and total lesions glycolysis/uptake (TLG_FDG and TLU_CXCR4), and the correlation between PET/CT-based response and clinical response, monoclonal protein and IgM response was analyzed.

Results

After chemotherapy, 5 patients had complete response or very good partial response, 8 had partial response or minimal response and 2 had progressive disease. In quantitative analysis, ⁶⁸Ga-pentixafor PET/CT-based response (measured in ∆TLU_CXCR4%, ∆MTV_CXCR4%, ∆SUVpeak%) showed a significant direct correlation with clinical response, monoclonal protein and IgM response (p < 0.01). However, ¹⁸F-FDG PET/CT-based response was independent from clinical response (p > 0.05).

Conclusions

The semi-quantitative measurements of ⁶⁸Ga-pentixafor PET/CT outperformed ¹⁸F-FDG PET/CT in response assessment of WM/LPL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-021-00852-0.

Bruton tyrosine kinase inhibitors for Waldenström macroglobulinemia: A review

OBJECTIVE

The objective of this review is to evaluate the available evidence for the Bruton tyrosine kinase inhibitors in the treatment of Waldenström macroglobulinemia.

DATA SOURCES

A search of the PubMed database was conducted using the following search terms: ibrutinib, PCI-32765, acalabrutinib, ACP-196, zanubrutinib, BGB-3111, and Waldenström macroglobulinemia. Prospective clinical trials evaluating the efficacy and safety of ibrutinib, acalabrutinib, and zanubrutinib in patients with Waldenström macroglobulinemia were evaluated. Abstracts from the American Society of Hematology and American Society of Clinical Oncology annual meetings were reviewed as well as the prescribing information for each drug.

DATA SUMMARY

The first-generation Bruton tyrosine kinase inhibitor ibrutinib received Food and Drug Administration approval for Waldenström macroglobulinemia in 2015; this was the first drug approved for this rare condition. Ibrutinib has been evaluated as monotherapy and in combination with rituximab for the treatment of Waldenström macroglobulinemia. Since then, second-generation Bruton tyrosine kinase inhibitors, acalabrutinib and zanubrutinib, have been evaluated in prospective clinical trials for the treatment of Waldenström macroglobulinemia. All three agents have demonstrated high overall response rates and durable responses.

CONCLUSION

Bruton tyrosine kinase inhibitors have demonstrated significant clinical activity in the treatment of Waldenström macroglobulinemia, both in treatment naïve as well as the relapsed/refractory patient populations.

Efficacy and safety of plasmapheresis in symptomatic hyperviscosity and cast nephropathy: A Multicenter Experience in Turkey

BACKGROUND AND OBJECTIVES

Cast nephropathy (CN) and hyperviscosity (HV), which we encounter in plasma cell diseases, are serious clinical manifestations that increase mortality and morbidity if not managed well in the early period. Therapeutic plasma exchange (TPE) procedures based on the removal of patient plasma is a frequently preferred treatment modality. TPE is recommended at varying levels of evidence for the treatment of CN and HV in plasma cell disorders.

MATERIAL AND METHODS

A total of 61 patients, 50 with multipl myeloma (MM) and 10 with Waldenström macroglobulinemia (WM), who underwent TPE for CN and HV, were included in our multicenter, and retrospective study.

RESULTS

A statistically significant decrease was found in all disease-related biochemical markers, which were measured 1 week after the application of TPE added to standard medical treatment (IgG; p < 0.001, IgM; p = 0.004, IgA; p = 0.14, kappa light chain; p < 0.001, lambda light chain; p < 0.001, β-2 microglobulin; p < 0.001, total protein; p < 0.001, albumin; p < 0.001, LDH; p = 0.02, creatine; p < 0.001, hemoglobin; p = 0.010). Clinically, all 11 patients who underwent TPE for HV responded. While a partial response (PR: 80 %) was obtained in 40 of 50 MM patients with CN, no response was obtained in 10 patients (non-response: 20 %).

CONCLUSION

In conclusion, it was observed that TPE reduced all biochemical markers related to HV and CN, while making a significant contribution to clinical improvement. We believe that adding TPE to the standard treatment in this patient group will reduce mortality and morbidity in the early period and have a positive effect on survival in the long term.

Chemokine Receptor 4-Targeted 68Ga-Pentixafor PET/CT in Response Assessment of Waldenström Macroglobulinemia/Lymphoplasmacytic Lymphoma: Comparison to 18F-FDG PET/CT

PURPOSE

68Ga-pentixafor PET/CT was reported to have a high sensitivity in detecting tumor involvement of Waldenström macroglobulinemia/lymphoplasmacytic lymphoma (WM/LPL) in our previous study. We aimed to further investigate its value in response assessment in WM/LPL.

PATIENTS AND METHODS

Fifteen patients with WM/LPL were recruited in a prospective cohort study and underwent both 68Ga-pentixafor and 18F-FDG PET/CT at baseline and posttreatment. PET/CT-based responses were analyzed with visual assessments and compared with clinical response.

RESULTS

At baseline, all of the 15 patients had a positive 68Ga-pentixafor PET/CT scan, whereas 18F-FDG PET/CT was positive in 11/15 patients. After chemotherapy, the overall response rate was 86.7% (13/15), and 68Ga-pentixafor PET/CT showed different degree of tumor response from baseline in these patients. In the 2 patients with progressive disease, 68Ga-pentixafor PET/CT detected new lesions or remarkable increase of 68Ga-pentixafor uptake in tumor involvements. However, 18F-FDG PET/CT failed to detect the improvement of disease in 6/13 patients and missed disease progression in 1 of the 2 patients.

CONCLUSIONS

68Ga-pentixafor PET/CT outperformed 18F-FDG PET/CT in response assessment of WM/LPL.

Ibrutinib plus rituximab for the treatment of adult patients with Waldenström's macroglobulinemia: a safety evaluation

Introduction: Waldenström's macroglobulinemia (WM), an orphan disease, is a rare low-grade B-cell lymphoplasmacytic lymphoma with unique clinical features and monoclonal IgM production. Rituximab remains to this date the backbone of most commonly used treatment combinations. The FDA/EMA approval of Ibrutinib, the first-in-class BTK inhibitor, either as monotherapy or in combination with rituximab, changed the treatment landscape of the disease.Areas covered: Clinical trial data that demonstrate mode of action, efficacy, and the safety profile of each agent will be covered. A safety analysis of the combination treatment will also be performed to point out its high efficacy and overall favorable toxicity profile. The disadvantages and treatment gaps that still exist in the treatment of WM which relate to the need for long-term ibrutinib administration and the lack of deep remissions and subsequent disease relapse, will also be reviewed.Expert opinion: The ibrutinib-rituximab combination is both effective and safe, in the newly-diagnosed and relapsed-refractory disease setting. The optimal therapeutic approach for WM patients remains however to be established. The question of which combinatory (or synergistic) regimen can allow for a fixed-treatment duration, deep and durable responses with a safe toxicity profile is being addressed in ongoing clinical trials.

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

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

Managing complications secondary to Waldenström's macroglobulinemia

Introduction: Waldenström's macroglobulinemia (WM) is a rare lymphoma characterized by the accumulation of IgM-secreting lymphoplasmacytic cells in the bone marrow and other organs. Clinical sequelae relate to direct tissue infiltration by malignant cells but also to the physicochemical and immunological properties of the monoclonal IgM, resulting in a variety of disease-related complications.Areas covered: This narrative review, following a thorough Pubmed search of pertinent published literature, discusses complications secondary to WM, related to direct tumor infiltration, monoclonal IgM circulation, and deposition, as well as other less common ones. The description and pathophysiology of these complications were described together with their specific management strategies and in the context of available treatment options for WM (anti-CD20 monoclonal antibody-based combinations, proteasome inhibitors, BTK inhibitors, and other emerging ones).Expert opinion: The availability of many novel, active and less toxic regimens for the treatment of WM allows the management of the disease with strategies that depend on clinical presentation and disease-related complications, age, toxicity considerations, and presence of comorbidities.

Treatment and outcome patterns of patients with Waldenström's macroglobulinemia: a large, multicenter retrospective review in China

In this study, we aimed to investigate treatment options and the prognosis of patients with WM in China. This retrospective study included 1141 patients diagnosed with symptomatic WM between January 2003 and December 2019 at 35 tertiary hospitals in 22 provinces of China. Fifty-four patients (7.3%) received monotherapy, 264 (36.0%) received chemoimmunotherapy, 395 (53.8%) received other combination regimens without rituximab, and 21 (2.9%) received ibrutinib. Using a multivariable Cox regression model, age > 65 years old, platelets <100 × 10⁹/L, serum albumin <3.5 g/dl, β2 microglobulin concentration ≥4 mg/L and LDH ≥250 IU/L predicted poor OS. In summary, our study showed that frontline treatment choices for WM are widely heterogeneous. We validated most of the established prognostic factors in the rIPSS (age >65 years, LDH ≥250 IU/L, ALB <3.5 g/dl and β2 microglobulin ≥4 mg/L) together with PLT ≤ 100 × 10⁹/L indicate a poor prognosis for patients with WM.

Hematologic disorder-associated Cxcr4 gain-of-function mutation leads to uncontrolled extrafollicular immune response

The extrafollicular immune response is essential to generate a rapid but transient wave of protective antibodies during infection. Despite its importance, the molecular mechanisms controlling this first response are poorly understood. Here, we demonstrate that enhanced Cxcr4 signaling caused by defective receptor desensitization leads to exacerbated extrafollicular B-cell response. Using a mouse model bearing a gain-of-function mutation of Cxcr4 described in 2 human hematologic disorders, warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome and Waldenström macroglobulinemia, we demonstrated that mutant B cells exhibited enhanced mechanistic target of rapamycin signaling, cycled more, and differentiated more potently into plasma cells than wild-type B cells after Toll-like receptor (TLR) stimulation. Moreover, Cxcr4 gain of function promoted enhanced homing and persistence of immature plasma cells in the bone marrow, a phenomenon recapitulated in WHIM syndrome patient samples. This translated in increased and more sustained production of antibodies after T-independent immunization in Cxcr4 mutant mice. Thus, our results establish that fine-tuning of Cxcr4 signaling is essential to limit the strength and length of the extrafollicular immune response.

Continuous MYD88 Activation Is Associated With Expansion and Then Transformation of IgM Differentiating Plasma Cells

Activating mutations of MYD88 (MYD88^L265P being the far most frequent) are found in most cases of Waldenström macroglobulinemia (WM) as well as in various aggressive B-cell lymphoma entities with features of plasma cell (PC) differentiation, such as activated B-cell type diffuse large B-cell lymphoma (DLBCL). To understand how MYD88 activation exerts its transformation potential, we developed a new mouse model in which the MYD88^L252P protein, the murine ortholog of human MYD88^L265P, is continuously expressed in CD19 positive B-cells together with the Yellow Fluorescent Protein (Myd88^L252P mice). In bone marrow, IgM B and plasma cells were expanded with a CD138 expression continuum from IgM^high CD138^low to IgM^low CD138^high cells and the progressive loss of the B220 marker. Serum protein electrophoresis (SPE) longitudinal analysis of 40 Myd88^L252P mice (16 to 56 weeks old) demonstrated that ageing was first associated with serum polyclonal hyper gammaglobulinemia (hyper Ig) and followed by a monoclonal immunoglobulin (Ig) peak related to a progressive increase in IgM serum levels. All Myd88^L252P mice exhibited spleen enlargement which was directly correlated with the SPE profile and was maximal for monoclonal Ig peaks. Myd88^L252P mice exhibited very early increased IgM PC differentiation. Most likely due to an early increase in the Ki67 proliferation index, IgM lymphoplasmacytic (LP) and plasma cells continuously expanded with age being first associated with hyper Ig and then with monoclonal Ig peak. This peak was consistently associated with a spleen LP-like B-cell lymphoma. Clonal expression of both membrane and secreted µ chain isoforms was demonstrated at the mRNA level by high throughput sequencing. The Myd88^L252P tumor transcriptomic signature identified both proliferation and canonical NF-κB p65/RelA activation. Comparison with MYD88^L265P WM showed that Myd88^L252P tumors also shared the typical lymphoplasmacytic transcriptomic signature of WM bone marrow purified tumor B-cells. Altogether these results demonstrate for the first time that continuous MYD88 activation is specifically associated with clonal transformation of differentiating IgM B-cells. Since MYD88^L252P targets the IgM PC differentiation continuum, it provides an interesting preclinical model for development of new therapeutic approaches to both WM and aggressive MYD88 associated DLBCLs.

Defining an Ultra-Low Risk Group in Asymptomatic IgM Monoclonal Gammopathy

Simple Summary

Patients with asymptomatic IgM monoclonal gammopathies include IgM monoclonal gammopathy of undetermined significance (IgM MGUS) and smoldering Waldenström macroglobulinemia (SWM), all with some risk of progression to symptomatic Waldenström macroglobulinemia, amyloidosis, or other lymphoproliferative disorder. Due to their low incidence, few studies have focused on the risk of progression, with SWM being the most studied. As both are recognized clinical-pathological entities that share similar clonal and phenotypical features, we focus on defining new biomarkers of progression in this population with long follow-up.

Abstract

We analyzed 171 patients with asymptomatic IgM monoclonal gammopathies (64 with IgM monoclonal gammopathy of undetermined significance—MGUS and 107 with smoldering Waldenström macroglobulinemia - SWM) who had a bone marrow (BM) evaluation performed at diagnosis. Abnormal free-light chain ratio (53% vs. 31%) and MYD88 mutation prevalence (66% vs. 30%) were higher in patients with SWM. No other differences were found among groups. With a median follow-up of 4.3 years, 14 patients progressed to Waldenström macroglobulinemia, 1 to amyloidosis, and 28 died without progression. The MYD88 mutation was found in 53% of patients (available in 160 patients). Multivariate analysis showed that immunoparesis (subhazard ratio—SHR 10.2, 95% confidence interval—CI: 4.2–24.8; p < 0.001) and BM lymphoplasmacytic infiltration ≥ 20% (SHR: 6, 95% CI: 1.6–22.1; p = 0.007) were associated with higher risk of progression. We developed a risk model based on these two risk factors. In the absence of both variables, an ultra-low risk group was identified (SHR 0.1, 95% CI 0.02–0.5; p = 0.004), with 3% and 6% of cumulative incidence of progression at 10 and 20 years, respectively. Bootstrap analysis confirmed the reproducibility of these results. This study finds immunoparesis and BM infiltration as biomarkers of progression as well as a low-risk group of progression in asymptomatic IgM monoclonal gammopathies.

Treatment Patterns and Outcomes in a Nationwide Cohort of Older and Younger Veterans with Waldenström Macroglobulinemia, 2006-2019

Simple Summary

Waldenström macroglobulinemia is a rare cancer about which little is known. Evidence from real-world settings provides invaluable information to patients and clinicians, especially for older and/or frailer patients, a demographic often excluded from clinical trials. This study provides information about treatment patterns and outcomes from real-world cohorts of older (>70 years) and younger (≤70 years) patients. We report findings across early (2006–2012) and modern (2013–2019) eras, reflecting a transition during which the number of treatments available for Waldenström macroglobulinemia rapidly increased. We found marked improvements in treatment outcomes among older patients in the modern vs early era, with little or no improvement in outcomes among younger patients. Our findings emphasize the importance of real-world evidence in guiding patient-specific treatment decisions.

Abstract

Little is known about real-world treatment patterns and outcomes in Waldenström macroglobulinemia (WM) following the recent introduction of newer treatments, especially among older adults. We describe patterns of first-line (1 L) WM treatment in early (2006–2012) and modern (2013–2019) eras and report outcomes (overall response rate (ORR), overall survival (OS), progression-free survival (PFS), and adverse event (AE)-related discontinuation) in younger (≤70 years) and older (>70 years) populations. We followed 166 younger and 152 older WM patients who received 1 L treatment between January 2006 and April 2019 in the Veterans Health Administration. Median follow-up was 43.5 months (range: 0.6–147.2 months). Compared to the early era, older patients in the modern era achieved improved ORRs (early: 63.8%, modern: 72.3%) and 41% lower risk of death/progression (hazard ratio (HR) for PFS: 0.59, 95% CI (confidence interval): 0.36–0.95), with little change in AE-related discontinuation between eras (HR: 0.82, 95% CI: 0.4–1.7). In younger patients, the AE-related discontinuation risk increased almost fourfold (HR: 3.9, 95% CI: 1.1–14), whereas treatment effects did not change between eras (HR for OS: 1.4, 95% CI: 0.66–2.8; HR for PFS: 1.1, 95% CI: 0.67–1.7). Marked improvements in survival among older adults accompanied a profound shift in 1 L treatment patterns for WM.

Circulating low CD4+/CD8+ ratio is associated with poor prognosis in Waldenstrom macroglobulinemia patients

Waldenstrom macroglobulinemia (WM) is a rare type of non-Hodgkin lymphoma with great heterogeneity, and the data of peripheral blood T-lymphocyte subsets in WM are limited. This study aimed to investigate the clinical correlation and distribution of circulating T-lymphocyte subsets in newly diagnosed WM patients. We retrospectively searched medical records for 86 newly diagnosed WM patients. Comparisons of the absolute CD3⁺ T-lymphocyte count (ACD3C), CD4⁺ T-lymphocyte count (ACD4C), CD8⁺ T-lymphocyte count (ACD8C), and CD4⁺/CD8⁺ T-lymphocyte ratio (CD4⁺/CD8⁺) as continuous parameters in different groups were calculated. Univariate and multivariate analyses were used to assess prognostic factors for overall survival (OS) and progression-free survival (PFS). Young patients (<65 years) had lower ACD8C levels and a higher CD4⁺/CD8⁺ ratio. And the lower level of β2-microglobulin (<3 mg/L) was associated with a higher CD4⁺/CD8⁺ ratio. With a median follow-up of 25 months, the univariate survival analysis showed that CD4⁺/CD8⁺ ratio inversion (CD4⁺/CD8⁺<1.5) was associated with shorter OS and PFS, and multivariate analysis confirmed that inverted CD4⁺/CD8⁺ ratio could be an independent adverse prognostic factor for OS and PFS. Additionally, initial treatment with rituximab or bortezomib significantly improved the PFS and OS of CD4⁺/CD8⁺ inversion patients but did not affect normal CD4⁺/CD8⁺ patients. We show that low circulating CD4⁺/CD8⁺ ratio at diagnosis is an adverse prognostic factor in WM patients and that first-line therapy which included rituximab or bortezomib significantly improved PFS and OS for patients with CD4⁺/CD8⁺ ratio less than 1.5.

Clinical application of genomics in Waldenström macroglobulinemia

Waldenström Macroglobulinemia (WM) is an incurable hematologic malignancy characterized by lymphoplasmacytic infiltration of the bone marrow and the presence of monoclonal immunoglobulin (IgM). Although a portion of WM patients may experience a relatively indolent course, patients may experience IgM-related morbidity and/or disease-related mortality. This underscores the need for novel approaches to improve response and survival rates. Significant progress had been made in our understanding of the genomics and biology of WM. The discovery of the highly recurrent somatic mutations in the MYD88 gene detected in 90-95% and the CXCR4 gene detected in 30-40% of WM patients has provided an opportunity to develop novel targeted approaches. Mutational status has important implications in predicting response to therapies such as BTK inhibitors. Treatment of WM should be guided by many factors including performance status, comorbidities, goals of therapy, and toxicities. In this review, we describe how current genomics may be utilized to optimize WM treatment selection. As the therapeutic landscape of WM continues to expand with more targeted approaches, the genomics in WM will likely play a greater role in individualizing treatment.

Current and novel BTK inhibitors in Waldenström's macroglobulinemia

The current therapeutic approach in Waldenström’s macroglobulinemia (WM) is being driven by insights in disease biology and genomic landscape. Bruton’s tyrosine kinase (BTK) plays a key role in signaling pathways for the survival of WM clone. BTK inhibition has changed the treatment landscape of the disease. Ibrutinib has resulted in deep and durable responses both as an upfront and salvage treatment with a manageable toxicity profile. However, the need for fewer off-target effects and deeper responses has resulted in the clinical development of second-generation BTK inhibitors. Zanubrutinib has resulted in clinically meaningful antitumor activity, including deep and durable responses, with a low discontinuation rate due to treatment-related toxicities. Cardiovascular adverse events seem to be milder compared with ibrutinib. Interestingly, the efficacy of zanubrutinib in WM is significant both for MYD88^L265P and MYD88^WT patients. Although the randomized, phase III ASPEN clinical trial did not meet its primary endpoint in terms of showing a superiority of zanubrutinib in deep responses compared with ibrutinib, secondary efficacy and safety endpoints underscore the potential clinical role of zanubrutinib in the treatment algorithm of WM independent of the MYD88 mutational status. Combination regimens and non-covalent BTK inhibitors are emerging as promising treatment strategies. Long-term data will determine whether next-generation BTK inhibitors are more potent and safer compared with ibrutinib, and whether they are able to overcome resistance to ibrutinib, either alone or in combination with inhibitors of other interrelated molecular pathways.

Inhibitors targeting Bruton's tyrosine kinase in cancers: drug development advances

Bruton's tyrosine kinase (BTK) inhibitor is a promising novel agent that has potential efficiency in B-cell malignancies. It took approximately 20 years from target discovery to new drug approval. The first-in-class drug ibrutinib creates possibilities for an era of chemotherapy-free management of B-cell malignancies, and it is so popular that gross sales have rapidly grown to more than 230 billion dollars in just 6 years, with annual sales exceeding 80 billion dollars; it also became one of the five top-selling medicines in the world. Numerous clinical trials of BTK inhibitors in cancers were initiated in the last decade, and ~73 trials were intensively announced or updated with extended follow-up data in the most recent 3 years. In this review, we summarized the significant milestones in the preclinical discovery and clinical development of BTK inhibitors to better understand the clinical and commercial potential as well as the directions being taken. Furthermore, it also contributes impactful lessons regarding the discovery and development of other novel therapies.

Novel Treatment Strategies in the Management of Waldenström Macroglobulinemia

PURPOSE OF REVIEW

Recent advances the genomic profiling of patients with Waldenström macroglobulinemia (WM) have led to the identification of novel therapeutic targets in these patients. In this review, we cover the current standard of care and the recently evaluated novel approaches with high potential to be incorporated in the therapeutic armamentarium against WM.

RECENT FINDINGS

The MYD88^L265P mutation is the most common genomic abnormality in WM, and is encountered in 80-95% of patients, making it an important target for drug development. The success of the first-generation Bruton tyrosine kinase (BTK) inhibitor, ibrutinib, has generated tremendous interest in the study of more selective and potent BTK inhibitors. Additionally, the identification of CXCR4^WHIM mutations in up to approximately 40% of patients with WM has fueled research regarding their implication on systemic therapy in WM. In a rapidly advancing field of targeted therapies, the treatment options for patients with WM are expanding as researchers continue to uncover and harness the survival pathways active in this hematologic malignancy.

Management of Waldenström macroglobulinemia in 2020

The management of Waldenström macroglobulinemia (WM) has evolved tremendously with recent genomic discoveries that correlate with clinical presentation and could help to tailor treatment approaches. The current diagnosis of WM requires clinicopathological criteria, including bone marrow involvement by lymphoplasmacytic lymphoma cells, a serum immunoglobulin M (IgM) monoclonal paraprotein, and presence of the MYD88 L265P mutation. Once the diagnosis is established, the relationship between the patient's symptoms and WM should be carefully investigated, because therapy should be reserved for symptomatic patients. Bone marrow involvement and serum levels of IgM, albumin, and β2-microglobulin can be used to estimate the time until treatment initiation. The treatment of WM patients should be highly personalized, and the patient's clinical presentation, comorbidities, genomic profile, and preferences, as well as toxicity of the treatment regimens, should be taken into account. Alkylating agents (bendamustine, cyclophosphamide), proteasome inhibitors (bortezomib, carfilzomib, ixazomib), anti-CD20 monoclonal antibodies (rituximab, ofatumumab), and Bruton tyrosine kinase (BTK) inhibitors (ibrutinib, acalabrutinib, zanubrutinib) are safe and highly effective treatment options in patients with WM. Because novel covalent and noncovalent BTK inhibitors (tirabrutinib, vecabrutinib, LOXO-305, ARQ-531), BCL2 antagonists (venetoclax), and CXCR4-targeting agents (ulocuplumab, mavorixafor) are undergoing clinical development in WM, the future of WM therapy certainly appears bright and hopeful.

Younger patients with Waldenström Macroglobulinemia exhibit low risk profile and excellent outcomes in the era of immunotherapy and targeted therapies

We analyzed 160 young Waldenström Macroglobulinemia (WM) patients with a median age of 49 years (range 23-55 years), diagnosed between January 2000 and January 2019 in 14 Italian centers. At diagnosis, 70% of patients were asymptomatic. With a median follow-up of 5.6 years, 57% have been treated. As initial therapy 79% of patients received chemo-immunotherapy, 13% a chemo-free induction and 8% chemotherapy only. At relapse or progression, 6% underwent an autologous stem cell transplantation. Overall, 19% of patients received ibrutinib during the course of the disease. According to IPSSWM, 63% were classified as low risk, 27% as intermediate risk and 10% as high risk. Five-year OS was shorter in high-risk as compared with low or intermediate risk patients (92.9% vs 100% P = .002). According to revised IPSSWM, 92% were classified as very low or low risk and 8% as intermediate risk, with a shorter 5-year OS in the latter group (87.5% vs 100%, P = .028). The OS of young WM patients was not significantly reduced as compared with age-matched, sex-matched and calendar year-matched general population. Early diagnosis, absence of high-risk features in symptomatic patients and high efficacy of modern treatments are the main determinants of the excellent outcome of young WM patients.

Chemokine receptor CXCR4: An important player affecting the molecular-targeted drugs commonly used in hematological malignancies

INTRODUCTION

A variety of molecular-targeted drugs have been widely used in hematological malignancies and have shown great advances. Nevertheless, as the use of drugs in clinical practice increases, the problem of relapse or of the disease being refractory to treatment is becoming apparent. This problem is closely related to the C-X-C chemokine receptor 4 (CXCR4).

AREAS COVERED

This review focuses mainly on the effect of CXCR4 on molecular-targeted drug resistance in hematological malignancies as well as the clinical efficacy of CXCR4 antagonists combined with molecular-targeted drugs. Relevant literatures published between 2006 and 2020 were searched using PubMed/Medline for this review.

EXPERT OPINION

Monoclonal antibodies and non-antibody molecular-targeted drugs provide new therapeutic approaches for B-lineage malignancies and leukemia, but the clinical activity of these drugs is affected by CXCR4. In general, high CXCR4 expression or mutation inhibits the effects of molecular-targeted drugs, but there are exceptions, and in studies of proteasome inhibitors bortezomib (Bz) in multiple myeloma (MM), low CXCR4 expression or loss of CXCR4 was associated with Bz resistance (BzR) and poor treatment outcomes. Given that CXCR4 is a critical mediator of molecular-targeted drug resistance, numerous studies have combined molecular-targeted drugs with CXCR4 antagonists, which synergistically enhance the anti-proliferative/pro-apoptotic effect of molecular-targeted drugs.

Systemic Amyloidosis due to Low-Grade Lymphoma

Lymphoma-related amyloidosis is a rare entity. Systemic AL amyloidosis is generally caused by an underlying plasma cell clone in the bone marrow with an intact monoclonal immunoglobulin G (IgG) or IgA protein. The rarity of the lymphoma-related amyloidosis makes the generation of data in randomized trials and the determination of the optimal treatment almost impossible. Therefore, treatment recommendations discussed here are based on either retrospective or small prospective trials of single centers.

Emerging drugs for the treatment of Waldenström macroglobulinemia

INTRODUCTION

Waldenström's Macroglobulinemia (WM) is an indolent lymphoma with uniquely distinct and heterogenous clinical and genomic profiles. Clonal lymphoplasmacytic cells secrete monoclonal IgM. More than 90% of patients harbor a mutation in MYD88 gene, leading to the constitutive activation of downstream pathways, involving BTK-mediated signaling. The use of BTK inhibitors has changed the treatment landscape of WM and has paved the way for new approaches to therapy.

AREAS COVERED

WM is an orphan disease and ibrutinib is the only FDA/EMA approved agent. Currently established agent combinations will be reviewed with a focus on emerging therapeutic options. These include second generation inhibitors, agents that target other molecules in the BCR signaling pathway, CXCR4 inhibitors, proteasome inhibitors and anti-CD38 antibodies. The current research goal is to establish a combination that can induce deep and durable responses with minimal associated toxicity. In addition, agents that can overcome ibrutinib resistance or act in a synergistic manner with BTKi are under investigation.

EXPERT OPINION

The optimal therapeutic approach for WM patients is not currently established. The question of whether a combinatory (or synergistic) regimen to overcome resistance and allow for fixed- duration treatment will allow for deep/durable responses is being addressed in ongoing clinical trials.