Toni Dubeau

Transcriptome sequencing reveals a profile that corresponds to genomic variants in Waldenström macroglobulinemia.

Whole-genome sequencing has identified highly prevalent somatic mutations including MYD88, CXCR4, and ARID1A in Waldenström macroglobulinemia (WM). The impact of these and other somatic mutations on transcriptional regulation in WM remains to be clarified. We performed next-generation transcriptional profiling in 57 WM patients and compared findings to healthy donor B cells. Compared with healthy donors, WM patient samples showed greatly enhanced expression of the VDJ recombination genes DNTT, RAG1, and RAG2, but not AICDA Genes related to CXCR4 signaling were also upregulated and included CXCR4, CXCL12, and VCAM1 regardless of CXCR4 mutation status, indicating a potential role for CXCR4 signaling in all WM patients. The WM transcriptional profile was equally dissimilar to healthy memory B cells and circulating B cells likely due increased differentiation rather than cellular origin. The profile for CXCR4 mutations corresponded to diminished B-cell differentiation and suppression of tumor suppressors upregulated by MYD88 mutations in a manner associated with the suppression of TLR4 signaling relative to those mutated for MYD88 alone. Promoter methylation studies of top findings failed to explain this suppressive effect but identified aberrant methylation patterns in MYD88 wild-type patients. CXCR4 and MYD88 transcription were negatively correlated, demonstrated allele-specific transcription bias, and, along with CXCL13, were associated with bone marrow disease involvement. Distinct gene expression profiles for patients with wild-type MYD88, mutated ARID1A, familial predisposition to WM, chr6q deletions, chr3q amplifications, and trisomy 4 are also described. The findings provide novel insights into the molecular pathogenesis and opportunities for targeted therapeutic strategies for WM.

Acquired mutations associated with ibrutinib resistance in Waldenström macroglobulinemia

Ibrutinib produces high response rates and durable remissions in Waldenström macroglobulinemia (WM) that are impacted by MYD88 and CXCR4WHIM mutations. Disease progression can develop on ibrutinib, although the molecular basis remains to be clarified. We sequenced sorted CD19+ lymphoplasmacytic cells from 6 WM patients who progressed after achieving major responses on ibrutinib using Sanger, TA cloning and sequencing, and highly sensitive and allele-specific polymerase chain reaction (AS-PCR) assays that we developed for Bruton tyrosine kinase (BTK) mutations. AS-PCR assays were used to screen patients with and without progressive disease on ibrutinib, and ibrutinib-naïve disease. Targeted next-generation sequencing was used to validate AS-PCR findings, assess for other BTK mutations, and other targets in B-cell receptor and MYD88 signaling. Among the 6 progressing patients, 3 had BTKCys481 variants that included BTKCys481Ser(c.1635G>C and c.1634T>A) and BTKCys481Arg(c.1634T>C) Two of these patients had multiple BTK mutations. Screening of 38 additional patients on ibrutinib without clinical progression identified BTKCys481 mutations in 2 (5.1%) individuals, both of whom subsequently progressed. BTKCys481 mutations were not detected in baseline samples or in 100 ibrutinib-naive WM patients. Using mutated MYD88 as a tumor marker, BTKCys481 mutations were subclonal, with a highly variable clonal distribution. Targeted deep-sequencing confirmed AS-PCR findings, and identified an additional BTKCys481Tyr(c.1634G>A) mutation in the 2 patients with multiple other BTKCys481 mutations, as well as CARD11Leu878Phe(c.2632C>T) and PLCγ2Tyr495His(c.1483T>C) mutations. Four of the 5 patients with BTKC481 variants were CXCR4 mutated. BTKCys481 mutations are common in WM patients with clinical progression on ibrutinib, and are associated with mutated CXCR4.

Atrial fibrillation associated with ibrutinib in Waldenström macroglobulinemia.

M. Schimmel, E. Nur and B.J. Biemond had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: MS, EN, LV, BB. Acquisition of data: MS, ROE. (Statistical) analysis and interpretation of data: MS, EN, DB, ROE, LV, BB. Drafting of the manuscript: MS, EN and BB. Critical revision of the manuscript for important intellectual content: all named co-authors.

Renal disease related to Waldenström macroglobulinaemia: incidence, pathology and clinical outcomes

The incidence and prognostic impact of nephropathy related to Waldenström macroglobulinaemia (WM) is currently unknown. We performed a retrospective study to assess biopsy‐confirmed WM‐related nephropathy in a cohort of 1391 WM patients seen at a single academic institution. A total of 44 cases were identified, the estimated cumulative incidence was 5·1% at 15 years. There was a wide variation in kidney pathology, some directly related to the WM: amyloidosis (n = 11, 25%), monoclonal‐IgM deposition disease/cryoglobulinaemia (n = 10, 23%), lymphoplasmacytic lymphoma infiltration (n = 8, 18%), light‐chain deposition disease (n = 4, 9%) and light‐chain cast nephropathy (n = 4, 9%), and some probably related to the WM: thrombotic microangiopathy (TMA) (n = 3, 7%), minimal change disease (n = 2, 5%), membranous nephropathy (n = 1, 2%) and crystal‐storing tubulopathy (n = 1, 2%). The median overall survival in patients with biopsy‐confirmed WM‐related nephropathy was 11·5 years, shorter than for the rest of the cohort (16 years, P = 0·03). Survival was better in patients with stable or improved renal function after treatment (P = 0·05). Based on these findings, monitoring for renal disease in WM patients should be considered and a kidney biopsy pursued in those presenting with otherwise unexplained renal failure and/or nephrotic syndrome.

Histological transformation to diffuse large B-cell lymphoma in patients with Waldenström macroglobulinemia.

Histological transformation to diffuse large B‐cell lymphoma (DLBCL) rarely occurs in patients with Waldenström Macroglobulinemia (WM). We identified 20 patients out of a cohort of 1,466 WM patients who experienced histologic transformation. The 5, 10, and 15‐year cumulative incidence rates were 1, 2.4, and 3.8%, respectively. Approximately half of the patients were naive to nucleoside analogues, and a quarter were previously untreated for WM at the time of transformation. More than 80% of patients presented with extranodal involvement, 65% with high IPI scores. DLBCL cells did not express CD10 but expressed BCL6 and BCL2. All patients were treated with chemoimmunotherapy. The median survival from histological transformation was 2.7 years. The median overall survival was shorter for transformed patients versus those who did not transform (estimated 9 vs. 16 years; P = 0.09). Histological transformation to DLBCL is rare, and is associated with inferior survival in WM. Am. J. Hematol. 91:1032–1035, 2016.

MYD88 wild-type Waldenstrom Macroglobulinaemia: differential diagnosis, risk of histological transformation, and overall survival

MYD88 mutations are present in 95% of Waldenstrom Macroglobulinaemia (WM) patients, and support diagnostic discrimination from other IgM‐secreting B‐cell malignancies. Diagnostic discrimination can be difficult among suspected wild‐type MYD88 (MYD88WT) WM cases. We systematically reviewed the clinical, pathological and laboratory studies for 64 suspected MYD88WT WM patients. World Health Organization and WM consensus guidelines were used to establish clinicopathological diagnosis. Up to 30% of suspected MYD88WT WM cases had an alternative clinicopathological diagnosis, including IgM multiple myeloma. The estimated 10‐year survival was 73% (95% confidence interval [CI] 52–86%) for MYD88WT versus 90% (95% CI 82–95%) for mutated (MYD88MUT) WM patients (Log‐rank P < 0·001). Multivariate analysis only showed MYD88 mutation status (P < 0·001) as a significant determinant for overall survival. Diffuse large B‐cell lymphoma (DLBCL) was diagnosed in 7 (15·2%) and 2 (0·76%) of MYD88WT and MYD88MUT patients, respectively (Odds ratio 23·3; 95% CI 4·2–233·8; P < 0·001). Overall survival was shorter among MYD88WT patients with an associated DLBCL event (Log‐rank P = 0·08). The findings show that among suspected MYD88WT WM cases, an alternative clinicopathological diagnosis is common and can impact clinical care. WM patients with MYD88WT disease have a high incidence of associated DLBCL events and significantly shorter survival versus those with MYD88MUT disease.

Idelalisib in Waldenström macroglobulinemia: high incidence of hepatotoxicity.

Waldenstr€ om macroglobulinemia (WM) is a rare B-cell lymphoma characterized by the accumulation of IgMsecreting lymphoplasmacytic cells.[1] Despite therapeutic advances, WM remains incurable, and novel treatment options are needed. Over 90% of patients with WM carry the MYD88 L265P gene mutation, which promotes the survival of WM cells through activation of the Bruton tyrosine kinase (BTK) pathway.[2] In a phase II study evaluating the BTK inhibitor ibrutinib in 63 patients with relapsed and/or refractory disease, an overall response rate (ORR) of 90% with acceptable toxicity was observed.[3] These results prompted the approval of ibrutinib by the United States Food and Drug Administration for use in patients with symptomatic WM. MYD88 L265P also promotes activation of the phosphatidylinositol-3-kinase (PI3K) pathway and exposure to the PI3K-delta inhibitor idelalisib induced robust killing in MYD88-mutated WM cells.[4] In a prior phase 2 study, 80% ORR was reported in 10 patients with WM, refractory to anti-CD20 and alkylating agents, treated with idelalisib 150mg twice daily.[5] In addition, a phase 1 study including nine relapsed/refractory WM patients treated with idelalisib reported 56% ORR.[6] Given these results, we initiated a prospective investigator-initiated phase 2 study to evaluate the safety and efficacy of idelalisib in patients with relapsed and/or refractory symptomatic WM (CinicalTrials.Gov identifier NCT02439138). The study was activated on 10 September 2015. All patients provided written informed consent after approval of the study by the Institutional Review Board at the Dana-Farber Cancer Institute. Gilead Sciences provided research funding and study drug. The primary objective was to determine response rates to idelalisib as defined by the 6th International Workshop in WM.[7] Serum IgM level, complete blood count, blood chemistries, liver function tests, bone marrow biopsy, and computed tomography (CT) scans were obtained at the beginning of the study. Eligibility criteria included a clinicopathological diagnosis of WM,[8] need for treatment according to guidelines,[9] at least one prior line of therapy, platelet count 50,000/mm, neutrophil count 1000/mm, creatinine level 2mg/dl, total bilirubin level 1.5mg/dl, aspartate and alanine aminotransferase levels 2.5 times the upper limit of normal, ECOG performance status of 2 or lower, and no active HIV, hepatitis B or C infection. The treatment regimen consisted of idelalisib at 150mg PO twice daily until disease progression or unacceptable toxicity. An allele-specific PCR assay was used to detect the MYD88 L265P mutation. CXCR4 mutational status was determined by Sanger sequencing. A one-stage design was used with alpha level at 0.05 and beta level at 0.20. This assumed a null ORR of 40% and a successful ORR of 70%. Our accrual goal was 30 patients. Five patients were enrolled in the study and received therapy. The median age at study entry was 66 years (range 57–80 years). Two patients met criteria for treatment due to anemia, one due to constitutional symptoms, one due to hyperviscosity, and one for evidence of renal involvement by lymphoplasmacytic lymphoma. The median number of prior therapies was 4 (range 3–9). All the patients were previously exposed to rituximab and bortezomib, four to alkylating agents, two to nucleoside analogs, and one to ibrutinib. The median bone marrow involvement was 40% (range 20–80%), the median IgM level was 4512mg/dl (range 3970–6190mg/dl), and the median hemoglobin level was 11g/dl (range 7.7–12.4g/dl). According to the International Prognostic Scoring System for WM, three patients were intermediate, one was low and one was high risk. The MYD88 L265P gene mutation was identified in all patients and CXCR4 mutations in two. Four patients were evaluable for response and exhibited stable disease on idelalisib. Patient 1 had previously progressed on ibrutinib therapy, and was not evaluable

Serum IgM level as predictor of symptomatic hyperviscosity in patients with Waldenström macroglobulinaemia

Symptomatic hyperviscosity is a common clinical manifestation in patients with Waldenström macroglobulinaemia (WM) and high serum IgM levels. Prompt intervention is required to prevent catastrophic events, such as retinal or central nervous system bleeding. Identifying patients at high risk of symptomatic hyperviscosity might support the decision to treat asymptomatic patients before irreversible damage occurs. We carried out a large retrospective study in 825 newly diagnosed WM patients, of who 113 (14%) developed symptomatic hyperviscosity. The median serum IgM level at the time of symptomatic hyperviscosity was 61·8 g/l (range 31–124 g/l). Forty‐four patients (36%) had symptomatic hyperviscosity at the time of WM diagnosis. A serum IgM level >60 g/l at diagnosis was associated with a median time to symptomatic hyperviscosity of 3 months, whereas the median time for patients with serum IgM level of 50·01–60 g/l was approximately 3 years. Adjusting for other clinical factors, the odds of developing symptomatic hyperviscosity were 370‐fold higher with serum IgM levels >60 g/l, and showed an association with CXCR4 mutational status. Symptomatic hyperviscosity did not impact overall survival (P = 0·12). The findings support the use of serum IgM level >60 g/l as a criterion for initiation of therapy in an otherwise asymptomatic WM patient.

Ibrutinib discontinuation in Waldenström macroglobulinemia: Etiologies, outcomes, and IgM rebound

Ibrutinib is the first approved therapy for symptomatic patients with Waldenström macroglobulinemia (WM). The reasons for discontinuing ibrutinib and subsequent outcomes have not been previously evaluated in WM patients. We therefore conducted a retrospective review of 189 WM patients seen at our institution who received treatment with ibrutinib, of whom 51 (27%) have discontinued therapy. Reasons for discontinuation include: disease progression (n = 27; 14%), toxicity (n = 15; 8%), nonresponse (n = 5; 3%), and other unrelated reasons (n = 4; 2%). The cumulative incidence of ibrutinib discontinuation at 12, 24, 36, and 48 months from treatment initiation was 22%, 26%, 35%, and 43%, respectively. A baseline platelet count ≤100 K/µL and presence of tumor CXCR4 mutations were independently associated with 4‐fold increased odds of ibrutinib discontinuation. An IgM rebound (≥25% increase in serum IgM) was observed in 37 patients (73%) following ibrutinib discontinuation and occurred within 4 weeks for nearly half of patients. The response rate to salvage therapy was 71%; responses were higher in patients without an IgM rebound and when salvage therapy was initiated within 2 weeks of stopping ibrutinib. Patients who discontinued ibrutinib due to disease progression versus nonprogression events had significantly shorter overall survival (21 versus 32 months; P = .046). Response to salvage therapy was associated with an 82% reduction in the risk of death following ibrutinib discontinuation. WM patients who discontinue ibrutinib require close monitoring, and continuation of ibrutinib until the next therapy should be considered to maintain disease control.

Prospective Clinical Trial of Ixazomib, Dexamethasone, and Rituximab as Primary Therapy in Waldenström Macroglobulinemia

Purpose: Proteasome inhibition is of proven efficacy in patients with Waldenström macroglobulinemia (WM). However, WM remains incurable with standard treatments. Novel agents, safe and effective, are needed. Patients and Methods: We designed a prospective phase II study evaluating the combination of ixazomib, dexamethasone, and rituximab (IDR) as primary therapy in symptomatic patients with WM. Protocol therapy consisted of oral ixazomib, 4 mg, with intravenous or oral dexamethasone, 20 mg, on days 1, 8, and 15 every 4 weeks for induction cycles 1 and 2, and in combination with intravenous rituximab, 375 mg/m2, on day 1, every 4 weeks for cycles 3 to 6. Maintenance therapy followed 8 weeks later with IDR given every 8 weeks for 6 cycles. Results: Twenty-six patients were enrolled. All patients had the MYD88 L265P mutation, and 15 patients (58%) had a CXCR4 mutation. The median time to response was 8 weeks, which was longer (12 weeks) in WM patients with CXCR4 mutations (P = 0.03). The overall response rate was 96%, and the major response rate was 77%. With a median follow-up of 22 months, the median progression-free survival was not reached. Grade ≥2 adverse events reported in >1 patient included infusion-related reactions (19%), rash (8%), and insomnia (8%). Conclusions: IDR offers a highly effective and well tolerated, neuropathy-sparing regimen for primary therapy in patients with WM. This trial is registered at www.clinicaltrials.gov under ID NCT02400437. Clin Cancer Res; 24(14); 3247–52. ©2018 AACR.