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In the era of widespread rituximab use for Waldenström's macroglobulinaemia, new treatment options for patients with rituximab-refractory disease are an important clinical need. Ibrutinib has induced durable responses in previously treated patients with Waldenström's macroglobulinaemia. We assessed the efficacy and safety of ibrutinib in a population with rituximab-refractory disease. This multicentre, open-label substudy was done at 19 sites in seven countries in adults aged 18 years and older with confirmed Waldenström's macroglobulinaemia, refractory to rituximab and requiring treatment. Disease refractory to the last rituximab-containing therapy was defined as either relapse less than 12 months since last dose of rituximab or failure to achieve at least a minor response. Key exclusion criteria included: CNS involvement, a stroke or intracranial haemorrhage less than 12 months before enrolment, clinically significant cardiovascular disease, hepatitis B or hepatitis C viral infection, and a known bleeding disorder. Patients received oral ibrutinib 420 mg once daily until progression or unacceptable toxicity. The substudy was not prospectively powered for statistical comparisons, and as such, all the analyses are descriptive in nature. This study objectives were the proportion of patients with an overall response, progression-free survival, overall survival, haematological improvement measured by haemoglobin, time to next treatment, and patient-reported outcomes according to the Functional Assessment of Cancer Therapy-Anemia (FACT-An) and the Euro Qol 5 Dimension Questionnaire (EQ-5D-5L). All analyses were per protocol. The study is registered at ClinicalTrials.gov, number NCT02165397, and follow-up is ongoing but enrolment is complete. Between Aug 18, 2014, and Feb 18, 2015, 31 patients were enrolled. Median age was 67 years (IQR 58–74); 13 (42%) of 31 patients had high-risk disease per the International Prognostic Scoring System Waldenström Macroglobulinaemia, median number of previous therapies was four (IQR 2–6), and all were rituximab-refractory. At a median follow-up of 18·1 months (IQR 17·5–18·9), the proportion of patients with an overall response was 28 [90%] of 31 (22 [71%] of patients had a major response), the estimated 18 month progression-free survival rate was 86% (95% CI 66–94), and the estimated 18 month overall survival rate was 97% (95% CI 79–100). Baseline median haemoglobin of 10·3 g/dL (IQR 9·3–11·7) increased to 11·4 g/dL (10·9–12·4) after 4 weeks of ibrutinib treatment and reached 12·7 g/dL (11·8–13·4) at week 49. A clinically meaningful improvement from baseline in FACT-An score, anaemia subscale score, and the EQ-5D-5L were reported at all post-baseline visits. Time to next treatment will be presented at a later date. Common grade 3 or worse adverse events included neutropenia in four patients (13%), hypertension in three patients (10%), and anaemia, thrombocytopenia, and diarrhoea in two patients each (6%). Serious adverse events occurred in ten patients (32%) and were most often infections. Five (16%) patients discontinued ibrutinib: three due to progression and two due to adverse events, while the remaining 26 [84%] of patients are continuing ibrutinib at the time of this report. The sustained responses and median progression-free survival time, combined with a manageable toxicity profile observed with single-agent ibrutinib indicate that this chemotherapy-free approach is a potential new treatment choice for patients who had heavily pretreated, rituximab-refractory Waldenström's macroglobulinaemia. Pharmacyclics LLC, an AbbVie Company.

A randomized trial comparing ibrutinib plus rituximab with rituximab alone in patients with Waldenström’s macroglobulinemia showed significantly higher rates of progression-free survival and overall response with the addition of ibrutinib.

We present the 6-year update of a phase 2 study evaluating the combination of obinutuzumab and idelalisib in relapse/refractory Waldenstrom macroglobulinemia. The results of the REMODEL trial demonstrated interesting efficacy in a high-risk genotype profile population. The primary endpoint was achieved with a median PFS of 25.4 months (95% CI, 15.7 to 29.0). However, a major limitation of idelalisib is its toxicity. With a median follow-up of 70.9 months, median OS was still not reached, and 5-year OS was 72.9% (95% CI, 61.3 to 86.6). We confirm that CXCR4 mutations had no impact on PFS or OS. However, TP53 mutated patients had shorter OS. At the time of analysis, six patients are alive without relapse and 40 had progressive disease. Among the 38 patients who received a new treatment, the median time to second progression was not reached in ibrutinib treated patients (n = 17) versus 30.8 months in patients treated with other options (95% CI, 16.9 to NA), p = 0.005. With longer follow-up our prospective study is the first to show an impact of TP53 mutations in patients treated with fixed duration chemo-free regimen leading to a significant shorter OS in this population. Moreover, ibrutinib remains an effective treatment after this combination. This study was registered on the clinicaltrial.gov web (NCT02962401, November 9, 2016).

Waldenstrom’s Macroglobulinemia (WM) is an IgM-secreting bone marrow (BM) lymphoma that is preceded by an asymptomatic state (AWM). To dissect tumor-intrinsic and immune mechanisms of progression, we perform single-cell RNA-sequencing on 294,206 BM tumor and immune cells from 30 patients with AWM/WM, 26 patients with Smoldering Myeloma, and 23 healthy donors. Despite their early stage, patients with AWM present extensive immune dysregulation, including in normal B cells, with disease-specific immune hallmarks. Patient T and NK cells show systemic hypo-responsiveness to interferon, which improves with interferon administration and may represent a therapeutic vulnerability. MYD88 -mutant tumors show transcriptional heterogeneity, which can be distilled in a molecular classification, including a DUSP22 / CD9 -positive subtype, and progression signatures which differentiate IgM MGUS from overt WM and can help advance WM research and clinical practice. The impact of tumor intrinsic and immune alterations on disease progression in patients with Waldenstrom’s Macroglobulinemia (WM) remains to be characterized. Here, the authors perform single-cell RNA-sequencing and identify distinct tumor subtypes, tumour microenvironment features and potential therapeutic vulnerabilities in patients with WM.

Waldenström macroglobulinaemia (WM) is a rare lymphoplasmacytic disease that is hallmarked by B‐cell infiltration of the bone marrow, an overexpression of IgM class antibodies and an activating mutation of MYD88 (L265P). The therapeutic options for WM patients include a combination of Rituximab (anti‐CD20 monoclonal antibody) and chemotherapy, with newer treatments like proteasomal inhibitors and Bruton's Tyrosine Kinase (BTK) inhibitors showing high levels of success both as monotherapy and in combinations. To date, WM remains incurable. Understanding the basic physiology of WM and creating new and improved pre‐clinical models which better reflect the true physiology of WM will allow for the identification of novel therapeutic vulnerabilities and the ability to test these next generation therapies, both in a tumour intrinsic and extrinsic manner. In this review, we aim to provide a comprehensive summary of WM, focusing on the genetic mutations and signalling pathways driving disease progression. In addition, we highlight the current therapeutics and emerging clinical trials to provide novel insights to drive deep and durable responses.

There remains a lack of consensus as to the most appropriate primary therapy in Waldenstrőm macroglobulinemia (WM). We evaluated a novel bortezomib-based combination and developed a sensitive WM-specific flow cytometry assay (limit of detection 0.004% of leucocytes) to assess bone marrow (BM) response. Sixty treatment-naïve WM patients were enroled into this phase II trial and randomised (2:1) to receive cyclophosphamide and rituximab with either bortezomib (BRC) or fludarabine (FCR). The primary objective was to assess the overall response rate (ORR) in eligible patients receiving BRC ( N  = 41). An ORR of 97.6% (95%CI:87.1–99.9) was observed; 27 (65.9%) patients remain alive without progression after 62.6 months median follow-up, with 2-, 3- and 5-year progression-free survival (PFS) rates of 92.7% (95%CI:79.0–97.6), 80.5% (95%CI:64.8–89.7) and 65.5% (95%CI:48.8–77.9). Persistent WM B-cells were demonstrable in 19/38 patients at the end of treatment (median 0.24%, range 0.02–11.2%). PFS was markedly longer in patients with BM B-cell depletion (<0.004%) compared to those who had persistent BM B-cells detectable at end of treatment (HR = 0.06, 95%CI:0.01–0.47, p  < 0.001), and remained independently associated after adjusting for baseline risk stratification or investigator-assessed response. BRC is a tolerable, highly efficacious regimen for treatment-naïve WM patients. BM B-cell depletion is independently associated with patient outcomes.

We evaluated the MYD88 L265P mutation in Waldenström’s macroglobulinemia (WM) and B-cell lymphoproliferative disorders by specific polymerase chain reaction (PCR) (sensitivity ∼10 −3 ). No mutation was seen in normal donors, while it was present in 101/117 (86%) WM patients, 27/31 (87%) IgM monoclonal gammapathies of uncertain significance (MGUS), 3/14 (21%) splenic marginal zone lymphomas and 9/48 (19%) non-germinal center (GC) diffuse large B-cell lymphomas (DLBCLs). The mutation was absent in all 28 GC-DLBCLs, 13 DLBCLs not subclassified, 35 hairy cell leukemias, 39 chronic lymphocytic leukemias (16 with M-component), 25 IgA or IgG-MGUS, 24 multiple myeloma (3 with an IgM isotype), 6 amyloidosis, 9 lymphoplasmacytic lymphomas and 1 IgM-related neuropathy. Among WM and IgM-MGUS, MYD88 L265P mutation was associated with some differences in clinical and biological characteristics, although usually minor; wild-type MYD88 cases had smaller M-component (1.77 vs 2.72 g/dl, P =0.022), more lymphocytosis (24 vs 5%, P =0.006), higher lactate dehydrogenase level (371 vs 265 UI/L, P =0.002), atypical immunophenotype (CD23−CD27++FMC7++), less Immunoglobulin Heavy Chain Variable gene (IGHV) somatic hypermutation (57 vs 97%, P =0.012) and less IGHV 3–23 gene selection (9 vs 27%, P =0.014). These small differences did not lead to different time to first therapy, response to treatment or progression-free or overall survival.

In a study conducted at three institutions, ibrutinib was associated with major responses in 73% of patients with Waldenström's macroglobulinemia who had received at least one previous treatment. Toxic effects of grade 2 or higher included neutropenia in 22% of the patients. Waldenström’s macroglobulinemia is a malignant B-cell lymphoma that is associated with an accumulation of clonal lymphoplasmacytic cells and monoclonal IgM secretion. 1 Despite advances in treatment, the disease eventually progresses in most patients, and new treatment options are needed. Whole-genome sequencing has revealed a single activating somatic mutation in MYD88 (resulting in a predicted protein change from leucine to proline at amino acid position 265) and multiple activating mutations in the C-terminal domain of CXCR4 in patients with Waldenström’s macroglobulinemia. 2 , 3 In tumor cells, MYD88L265P triggers activation of nuclear factor κB (NF-κB) through two divergent pathways involving Bruton’s tyrosine kinase (BTK) . . .

Patients with Waldenström's macroglobulinemia without mutations in MYD88 tend to have a shorter median survival and a lower probability of response to ibrutinib than do those with MYD88 mutations. To the Editor: Whole-genome sequencing identified the MYD88 L265P variant as the most prevalent mutation in patients with Waldenström's macroglobulinemia (WM), a type of non-Hodgkin's lymphoma. 1 In 93 to 97% of patients with this disorder, allele-specific polymerase-chain-reaction (AS-PCR) assays identified MYD88 L265P, which results from a T→C transversion at position 38182641 on chromosome 3p22.2. Signaling studies showed that the mutant protein that is encoded by MYD88 L265P triggers tumor growth through the activation of nuclear factor kappa light-chain enhancer of activated B cells (NF-κB) by Bruton's tyrosine kinase. This kinase is targeted by ibrutinib, a drug that is widely used . . .

Waldenström's macroglobulinemia is a lymphoplasmacytic lymphoma. Genetic analysis has revealed a common mutation (L265P) in MYD88 in more than 90% of patients with this disease. The mutation appears to activate NF-κB. Waldenström's macroglobulinemia is an IgM-secreting lymphoplasmacytic lymphoma (LPL). 1 , 2 Clinical manifestations of Waldenström's macroglobulinemia include cytopenia resulting from bone marrow infiltration by lymphoplasmacytic cells, paraprotein-related cryoglobulinemia, the cold agglutinin syndrome, demyelinating neuropathy, and symptomatic hyperviscosity. 3 The oncogenic basis of Waldenström's macroglobulinemia has not been defined. Familial clustering of Waldenström's macroglobulinemia and other B-cell disorders suggests that genetic factors play a role in the pathogenesis of Waldenström's macroglobulinemia in certain patients. 4 – 6 IgM monoclonal gammopathy of unknown significance (MGUS) is characterized by the presence of a monoclonal IgM protein and the absence of bone marrow disease involvement on histologic examination. 1 IgM . . .