Christina Tripsas

MYD88 L265P Somatic Mutation in Waldenström's Macroglobulinemia

BACKGROUND Waldenströms macroglobulinemia is an incurable, IgM-secreting lymphoplasmacytic lymphoma (LPL). The underlying mutation in this disorder has not been delineated. METHODS We performed whole-genome sequencing of bone marrow LPL cells in 30 patients with Waldenströms macroglobulinemia, with paired normal-tissue and tumor-tissue sequencing in 10 patients. Sanger sequencing was used to validate the findings in samples from an expanded cohort of patients with LPL, those with other B-cell disorders that have some of the same features as LPL, and healthy donors. RESULTS Among the patients with Waldenströms macroglobulinemia, a somatic variant (T→C) in LPL cells was identified at position 38182641 at 3p22.2 in the samples from all 10 patients with paired tissue samples and in 17 of 20 samples from patients with unpaired samples. This variant predicted an amino acid change (L265P) in MYD88, a mutation that triggers IRAK-mediated NF-κB signaling. Sanger sequencing identified MYD88 L265P in tumor samples from 49 of 54 patients with Waldenströms macroglobulinemia and in 3 of 3 patients with non-IgM-secreting LPL (91% of all patients with LPL). MYD88 L265P was absent in paired normal tissue samples from patients with Waldenströms macroglobulinemia or non-IgM LPL and in B cells from healthy donors and was absent or rarely expressed in samples from patients with multiple myeloma, marginal-zone lymphoma, or IgM monoclonal gammopathy of unknown significance. Inhibition of MYD88 signaling reduced IκBα and NF-κB p65 phosphorylation, as well as NF-κB nuclear staining, in Waldenströms macroglobulinemia cells expressing MYD88 L265P. Somatic variants in ARID1A in 5 of 30 patients (17%), leading to a premature stop or frameshift, were also identified and were associated with an increased disease burden. In addition, 2 of 3 patients with Waldenströms macroglobulinemia who had wild-type MYD88 had somatic variants in MLL2. CONCLUSIONS MYD88 L265P is a commonly recurring mutation in patients with Waldenströms macroglobulinemia that can be useful in differentiating Waldenströms macroglobulinemia and non-IgM LPL from B-cell disorders that have some of the same features. (Funded by the Peter and Helen Bing Foundation and others.).

Ibrutinib in Previously Treated Waldenström's Macroglobulinemia

BACKGROUND MYD88(L265P) and CXCR4(WHIM) mutations are highly prevalent in Waldenströms macroglobulinemia. MYD88(L265P) triggers tumor-cell growth through Brutons tyrosine kinase, a target of ibrutinib. CXCR4(WHIM) mutations confer in vitro resistance to ibrutinib. METHODS We performed a prospective study of ibrutinib in 63 symptomatic patients with Waldenströms macroglobulinemia who had received at least one previous treatment, and we investigated the effect of MYD88 and CXCR4 mutations on outcomes. Ibrutinib at a daily dose of 420 mg was administered orally until disease progression or the development of unacceptable toxic effects. RESULTS After the patients received ibrutinib, median serum IgM levels decreased from 3520 mg per deciliter to 880 mg per deciliter, median hemoglobin levels increased from 10.5 g per deciliter to 13.8 g per deciliter, and bone marrow involvement decreased from 60% to 25% (P<0.01 for all comparisons). The median time to at least a minor response was 4 weeks. The overall response rate was 90.5%, and the major response rate was 73.0%; these rates were highest among patients with MYD88(L265P)CXCR4(WT) (with WT indicating wild-type) (100% overall response rate and 91.2% major response rate), followed by patients with MYD88(L265P)CXCR4(WHIM) (85.7% and 61.9%, respectively) and patients with MYD88(WT)CXCR4(WT) (71.4% and 28.6%). The estimated 2-year progression-free and overall survival rates among all patients were 69.1% and 95.2%, respectively. Treatment-related toxic effects of grade 2 or higher included neutropenia (in 22% of the patients) and thrombocytopenia (in 14%), which were more common in heavily pretreated patients; postprocedural bleeding (in 3%); epistaxis associated with the use of fish-oil supplements (in 3%); and atrial fibrillation associated with a history of arrhythmia (5%). CONCLUSIONS Ibrutinib was highly active, associated with durable responses, and safe in pretreated patients with Waldenströms macroglobulinemia. MYD88 and CXCR4 mutation status affected responses to this drug. (Funded by Pharmacyclics and others; ClinicalTrials.gov number, NCT01614821.).

MYD88 L265P in Waldenström macroglobulinemia, immunoglobulin M monoclonal gammopathy, and other B-cell lymphoproliferative disorders using conventional and quantitative allele-specific polymerase chain reaction

By whole-genome and/or Sanger sequencing, we recently identified a somatic mutation (MYD88 L265P) that stimulates nuclear factor κB activity and is present in >90% of Waldenström macroglobulinemia (WM) patients. MYD88 L265P was absent in 90% of immunoglobulin M (IgM) monoclonal gammopathy of undetermined significance (MGUS) patients. We therefore developed conventional and real-time allele-specific polymerase chain reaction (AS-PCR) assays for more sensitive detection and quantification of MYD88 L265P. Using either assay, MYD88 L265P was detected in 97 of 104 (93%) WM and 13 of 24 (54%) IgM MGUS patients and was either absent or rarely expressed in samples from splenic marginal zone lymphoma (2/20; 10%), CLL (1/26; 4%), multiple myeloma (including IgM cases, 0/14), and immunoglobulin G MGUS (0/9) patients as well as healthy donors (0/40; P < 1.5 × 10(-5) for WM vs other cohorts). Real-time AS-PCR identified IgM MGUS patients progressing to WM and showed a high rate of concordance between MYD88 L265P ΔCT and BM disease involvement (r = 0.89, P = .008) in WM patients undergoing treatment. These studies identify MYD88 L265P as a widely present mutation in WM and IgM MGUS patients using highly sensitive and specific AS-PCR assays with potential use in diagnostic discrimination and/or response assessment. The finding of this mutation in many IgM MGUS patients suggests that MYD88 L265P may be an early oncogenic event in WM pathogenesis.

The genomic landscape of Waldenström macroglobulinemia is characterized by highly recurring MYD88 and WHIM-like CXCR4 mutations, and small somatic deletions associated with B-cell lymphomagenesis

The genetic basis for Waldenström macroglobulinemia (WM) remains to be clarified. Although 6q losses are commonly present, recurring gene losses in this region remain to be defined. We therefore performed whole genome sequencing (WGS) in 30 WM patients, which included germline/tumor sequencing for 10 patients. Validated somatic mutations occurring in >10% of patients included MYD88, CXCR4, and ARID1A that were present in 90%, 27%, and 17% of patients, respectively, and included the activating mutation L265P in MYD88 and warts, hypogammaglobulinemia, infection, and myelokathexis-syndrome-like mutations in CXCR4 that previously have only been described in the germline. WGS also delineated copy number alterations (CNAs) and structural variants in the 10 paired patients. The CXCR4 and CNA findings were validated in independent expansion cohorts of 147 and 30 WM patients, respectively. Validated gene losses due to CNAs involved PRDM2 (93%), BTG1 (87%), HIVEP2 (77%), MKLN1 (77%), PLEKHG1 (70%), LYN (60%), ARID1B (50%), and FOXP1 (37%). Losses in PLEKHG1, HIVEP2, ARID1B, and BCLAF1 constituted the most common deletions within chromosome 6. Although no recurrent translocations were observed, in 2 patients deletions in 6q corresponded with translocation events. These studies evidence highly recurring somatic events, and provide a genomic basis for understanding the pathogenesis of WM.

Carfilzomib, rituximab, and dexamethasone (CaRD) treatment offers a neuropathy-sparing approach for treating Waldenström's macroglobulinemia

Bortezomib frequently produces severe treatment-related peripheral neuropathy (PN) in Waldenströms macroglobulinemia (WM). Carfilzomib is a neuropathy-sparing proteasome inhibitor. We examined carfilzomib, rituximab, and dexamethasone (CaRD) in symptomatic WM patients naïve to bortezomib and rituximab. Protocol therapy consisted of intravenous carfilzomib, 20 mg/m2 (cycle 1) and 36 mg/m(2) (cycles 2-6), with intravenous dexamethasone, 20 mg, on days 1, 2, 8, and 9, and rituximab, 375 mg/m(2), on days 2 and 9 every 21 days. Maintenance therapy followed 8 weeks later with intravenous carfilzomib, 36 mg/m(2), and intravenous dexamethasone, 20 mg, on days 1 and 2, and rituximab, 375 mg/m(2), on day 2 every 8 weeks for 8 cycles. Overall response rate was 87.1% (1 complete response, 10 very good partial responses, 10 partial responses, and 6 minimal responses) and was not impacted by MYD88(L265P) or CXCR4(WHIM) mutation status. With a median follow-up of 15.4 months, 20 patients remain progression free. Grade ≥2 toxicities included asymptomatic hyperlipasemia (41.9%), reversible neutropenia (12.9%), and cardiomyopathy in 1 patient (3.2%) with multiple risk factors, and PN in 1 patient (3.2%) which was grade 2. Declines in serum IgA and IgG were common. CaRD offers a neuropathy-sparing approach for proteasome inhibitor-based therapy in WM. This trial is registered at www.clinicaltrials.gov as #NCT01470196.

Bendamustine therapy in patients with relapsed or refractory Waldenström's macroglobulinemia.

We report the treatment outcome for 30 relapsed/refractory Waldenströms macroglobulinemia (WM) patients following bendamustine-containing therapy. Treatment consisted of bendamustine (90 mg/m2 I.V. on days 1, 2) and rituximab (375 mg/m2 I.V. on either day 1 or 2) for 24 patients. Six rituximab-intolerant patients received bendamustine alone (n=4) or with ofatumumab (1000 mg I.V. on day 1; n=2). Each cycle was 4 weeks, and median number of treatment cycles was 5. At best response, median serum IgM declined from 3980 to 698 mg/dL (P<.0001), and hematocrit rose from 31.9% to 36.6% (P=.0002). Overall response rate was 83.3%, with 5 VGPR and 20 PR. The median estimated progression-free survival for all patients was 13.2 months. Overall therapy was well tolerated. Prolonged myelosuppression was more common in patients who received prior nucleoside analogues. Bendamustine is active and produces durable responses in previously treated WM, both as monotherapy and with CD20-directed monoclonal antibodies.

Detection of MYD88 L265P in peripheral blood of patients with Waldenström’s Macroglobulinemia and IgM monoclonal gammopathy of undetermined significance

MYD88 L265P is highly prevalent in Waldenstrom’s Macroglobulinemia (WM) and IgM monoclonal gammopathy of unknown significance (MGUS). We investigated whether MYD88 L265P could be identified by peripheral blood (PB) allele-specific PCR. MYD88 L265P was detected in untreated WM (114/118; 96.6%); previously treated WM (63/102; 61.8%); and IgM MGUS (5/12; 41.7%) but in none of 3 hyper-IgM or 40 healthy individuals. Median PB MYD88 L265P ΔCt was 3.77, 7.24, 10.89, 12.33 and 14.07 for untreated WM, previously treated WM, IgM MGUS, hyper-IgM and healthy individuals, respectively (P<0.0001). For the 232 IgM MGUS and WM patients, PB MYD88 L265P ΔCt moderately correlated to bone marrow (BM) disease (r=−0.3553; P<0.0001), serum IgM (r=−0.3262; P<0.0001) and hemoglobin (r=0.3005; P<0.0001) levels. PB MYD88 L265P ΔCt and serum IgM correlated similarly with BM disease burden. For positive patients, PB MYD88 L265P ΔCt was <6.5 in 100/114 (88%) untreated WM, and >6.5 in 4/5 (80%) IgM MGUS patients (P=0.0034). Attainment of a negative PB MYD88 L265P mutation status was associated with lower BM disease (P=0.001), serum IgM (P=0.019) and higher hemoglobin (P=0.004) levels in treated patients. These studies show the feasibility for detecting MYD88 L265P by PB examination, and the potential for PB MYD88 L265P ΔCt use in the diagnosis and management of WM patients.

Associated Malignancies in Patients with Waldenström's Macroglobulinemia and Their Kin

We examined the incidence of other malignancies in 924 Waldenströms Macroglobulinemia (WM) patients and their kin. A total of 225 (24.3%) patients had ≥1 additional malignancy, with 63% predating the WM diagnosis. The most common gender-adjusted malignancies were prostate (9.4%), breast (8.0%), non-melanoma skin (7.1%), hematologic (2.8%), melanoma (2.2%), lung (1.4%) and thyroid 1.1%). Among hematologic malignancies, all 13 cases of diffuse large B-cell lymphoma and 4 cases of acute myelogenous leukemia were diagnosed after WM, and were therapy-related. Familial WM subgroup analysis showed a higher incidence of prostate cancer (P=.046) in sporadic WM patients, while patients with familial WM had a higher incidence of lung cancer (P=.0043). An increased incidence of myeloid leukemias (P<.0001) was reported among kin of familial WM patients. These data reveal specific cancer associations with WM, and provide a basis for exploratory studies aimed at delineating a common genetic basis. Additionally, these studies suggest specific cancer clustering based on familial predisposition to WM.

Familial Disease Predisposition Impacts Treatment Outcome in Patients With Waldenström Macroglobulinemia

UNLABELLED Familial disease is common in Waldenström macroglobulinemia (WM). We examined the impact of familial disease status on treatment outcome in WM and observed that familial disease was associated with inferior outcomes. However patients with familial WM receiving a bortezomib-containing regimen showed improved treatment outcomes vs. those receiving non–bortezomib-containing regimens. Bortezomib-containing regimens may therefore represent a more optimal treatment approach for patients with familial WM. BACKGROUND We examined the impact of familial predisposition on treatment outcome in 135 patients with Waldenström macroglobulinemia (WM), 26.7% of whom had first- or second-degree relatives with a B-cell lymphoproliferative disorder. PATIENTS AND METHODS All patients were rituximab naive and received a rituximab-containing regimen. There were no significant differences in baseline characteristics between cohorts. RESULTS Overall response (93.9% vs. 75.0%; P = .029) and complete response/very good partial response (CR/VGPR) (23.2% vs. 16.7%; P < .0001), time to progression (TTP) (45.5 vs. 21 months; P = .015) and time to next therapy (TTNT) (50.0 vs. 33.0 months; P = .024) favored patients with sporadic WM. By multivariate analysis, familial predisposition was an independent marker for disease progression (hazard ratio, 0.554). Patients with familial but not sporadic disease exhibited better responses, including CR/VGPR attainment (P = .0006) and a trend for longer progression-free survival (> 33 vs. 20.6 months; P = .08), with bortezomib-containing therapy. CONCLUSION The findings convey that familial predisposition is an important determinant of treatment outcome in WM. Prospective studies to confirm these observations are needed.

Patients With Waldenström Macroglobulinemia Commonly Present With Iron Deficiency and Those With Severely Depressed Transferrin Saturation Levels Show Response to Parenteral Iron Administration

Anemia often prompts therapy in Waldenström macroglobulinemia (WM), although is not fully explained by bone marrow disease involvement in many patients. Hepcidin regulates gut absorption and distribution of iron and is elevated and associated with anemia in WM. Since hepcidin evaluation remains experimental, we initiated an American Board of Internal Medicine (ABIM) practice improvement project to determine baseline transferrin saturation (TSAT) levels in untreated anemic patients with WM. Among 108 patients with WM evaluated, 56 (52%) had a TSAT level ≤ 20%, which included 25 (23%) patients with severely depressed TSAT levels (≤ 10%). Sixteen patients with TSAT levels ≤ 10% received parenteral iron, and 14 of these patients showed improved hematocrit values (28.75% to 32.75%; P < .0001), mean corpuscular volume (MCV) (84.7 to 89.9; P = .006), and TSAT levels (8.1% to 21.2%; P < .0001). Anemia in 8 of these patients was previously refractory to oral iron therapy. Routine screening of iron saturation levels may therefore identify patients with WM and severe iron deficiency who may be candidates for parenteral iron therapy.