Marzia Varettoni

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.

Prognostic factors for thrombosis, myelofibrosis, and leukemia in essential thrombocythemia: a study of 605 patients

The findings from this study on a large series of patients treated according to current clinical practice provide reassurance that essential thrombocythemia is an indolent disorder and affected patients have a long survival. Background Essential thrombocythemia is a chronic myeloproliferative disorder; patients with this disorder have a propensity to develop thrombosis, myelofibrosis, and leukemia. Design and Methods We studied 605 patients with essential thrombocythemia (follow-up 4596 person-years) with the aim of defining prognostic factors for thrombosis, myelofibrosis, and leukemia during follow-up. Results Sixty-six patients (11%) developed thrombosis with a 10-year risk of 14%. Age >60 years (p<0.001) and a history of thrombosis (p=0.03) were independent risk factors for thrombosis. Progression to myelofibrosis occurred in 17 patients (2.8%) with a 10-year risk of 3.9%. Anemia at diagnosis of essential thrombocythemia was significantly correlated (p<0.001) with progression to myelofibrosis. Leukemia occurred in 14 patients (2.3%) at a median time of 11 years after the diagnosis of essential thrombocythemia; the risk was 2.6% at 10 years. Age >60 years (p=0.02) was significantly correlated with the development of leukemia. Cytotoxic treatment did not imply a higher risk of leukemia. At the time of the analysis, 64 of the 605 patients (10.6%) had died. The 10-year probability of survival was 88%, with a median survival of 22.3 years. Age >60 years (p<0.001) and history of thrombosis (p=0.001) were independent risk factors for survival. Conclusions The findings from this study on a large series of patients treated according to current clinical practice provide reassurance that essential thrombocythemia is an indolent disorder and affected patients have a long survival. The main risk is thrombosis, while myelofibrosis and leukemia are rare and late complications.

Prevalence and clinical significance of the MYD88 (L265P) somatic mutation in Waldenstrom's macroglobulinemia and related lymphoid neoplasms.

A study has shown that MYD88 (L265P) is a recurring somatic mutation in Waldenströms macroglobulinemia (WM). We developed an allele-specific polymerase chain reaction (PCR) for this mutation, and analyzed bone marrow or peripheral blood samples from 58 patients with WM, 77 with IgM monoclonal gammopathy of undetermined significance (IgM-MGUS), 84 with splenic marginal zone lymphoma (SMZL), and 52 with B-cell chronic lymphoproliferative disorders (B-CLPD). MYD88 (L265P) was detected in 58/58 (100%) patients with WM, 36/77 (47%) with IgM-MGUS, 5/84 (6%) with SMZL, and 3/52 (4%) with B-CLPD. Compared to IgM-MGUS patients with wild-type MYD88, those carrying MYD88 (L265P) showed significantly higher levels of IgM (P < .0001) and presented Bence-Jones proteinuria more frequently at diagnosis (P = .002). During follow-up, 9 patients with IgM-MGUS progressed to WM or to marginal zone lymphoma. Using a case-control approach, the risk of evolution of patients carrying MYD88 (L265P) was significantly higher than that of patients with wild-type MYD88 (odds ratio 4.7, 95% confidence interval 0.8 to 48.7, P = .047). These findings indicate that the allele-specific PCR we developed is a useful diagnostic tool for patients with WM or IgM-MGUS. In this latter condition, MYD88 (L265P) is associated with greater disease burden and higher risk of disease progression, and the mutation may therefore also represent a useful prognostic marker.

The BRAF V600E mutation in hairy cell leukemia and other mature B-cell neoplasms

The somatically acquired V600E mutation of the BRAF gene has been recently described as a molecular marker of hairy cell leukemia (HCL). We developed an allele-specific PCR for this mutation and studied 62 patients with HCL, 1 with HCL variant, 91 with splenic marginal zone lymphoma, 29 with Waldenström macroglobulinemia, and 57 with B-cell chronic lymphoproliferative disorders. The BRAF V600E mutation was detected in all HCL cases and in only 2 of the remaining 178 patients. These 2 subjects had B-cell chronic lymphoproliferative disorders that did not fulfill the diagnostic criteria for HCL. Despite the positive PCR finding, the mutation could not be detected by Sanger sequencing in these 2 cases, suggesting that it was associated with a small subclone. We conclude that the BRAF V600E mutation is present in all patients with HCL and that, in combination with clinical and morphologic features, represents a reliable molecular marker for this condition.

Targeting Mutant BRAF in Relapsed or Refractory Hairy-Cell Leukemia

BACKGROUND BRAF V600E is the genetic lesion underlying hairy-cell leukemia. We assessed the safety and activity of the oral BRAF inhibitor vemurafenib in patients with hairy-cell leukemia that had relapsed after treatment with a purine analogue or who had disease that was refractory to purine analogues. METHODS We conducted two phase 2, single-group, multicenter studies of vemurafenib (at a dose of 960 mg twice daily)--one in Italy and one in the United States. The therapy was administered for a median of 16 weeks in the Italian study and 18 weeks in the U.S. study. Primary end points were the complete response rate (in the Italian trial) and the overall response rate (in the U.S. trial). Enrollment was completed (28 patients) in the Italian trial in April 2013 and is still open (26 of 36 planned patients) in the U.S. trial. RESULTS The overall response rates were 96% (25 of 26 patients who could be evaluated) after a median of 8 weeks in the Italian study and 100% (24 of 24) after a median of 12 weeks in the U.S. study. The rates of complete response were 35% (9 of 26 patients) and 42% (10 of 24) in the two trials, respectively. In the Italian trial, after a median follow-up of 23 months, the median relapse-free survival was 19 months among patients with a complete response and 6 months among those with a partial response; the median treatment-free survival was 25 months and 18 months, respectively. In the U.S. trial, at 1 year, the progression-free survival rate was 73% and the overall survival rate was 91%. Drug-related adverse events were usually of grade 1 or 2, and the events most frequently leading to dose reductions were rash and arthralgia or arthritis. Secondary cutaneous tumors (treated with simple excision) developed in 7 of 50 patients. The frequent persistence of phosphorylated ERK-positive leukemic cells in bone marrow at the end of treatment suggests bypass reactivation of MEK and ERK as a resistance mechanism. CONCLUSIONS A short oral course of vemurafenib was highly effective in patients with relapsed or refractory hairy-cell leukemia. (Funded by the Associazione Italiana per la Ricerca sul Cancro and others; EudraCT number, 2011-005487-13; ClinicalTrials.gov number NCT01711632.).

Fludarabine plus cyclophosphamide and rituximab in waldenstrom macroglobulinemia: An effective but myelosuppressive regimen to be offered to patients with advanced disease

The combination of fludarabine, cyclophosphamide, and rituximab (FCR) has produced promising results in chronic lymphocytic leukemia and other lymphoproliferative disorders. The authors report the final results from a multicenter, prospective study examining FCR in Waldenstrom macroglobulinemia (WM).

Bortezomib-induced peripheral neuropathy in multiple myeloma: A comparison between previously treated and untreated patients

Peripheral neuropathy (PN), with neuropathic pain as main symptom, represents the dose-limiting toxicity of the proteasome inhibitor bortezomib. Aim of this study was to compare the incidence, risk factors, severity and outcome of PN and neuropathic pain in patient treated with bortezomib up-front or at relapse. We studied 55 patients with multiple myeloma (MM) who received bortezomib as first line therapy and 70 pre-treated patients who received bortezomib in relapse or progression. Regarding PN, no differences were found among untreated and pre-treated patients in the incidence (55% vs 52%, p=0.43), severity (NCI grade 3-4 9% vs 14%, p=0.27), and outcome (improved/resolved 90% vs 91%, p=0.58). Concerning neuropathic pain, the incidence was lower (50% vs 81%, p=0.008) and solved earlier (35 days vs 91 days, p=0.02) in untreated compared with pre-treated patients. Untreated patients needed dose modification less frequently (36% vs 73%, p=0.012). No correlation was found between development of PN and prior exposure to potentially neurotoxic drugs such as thalidomide, vincristine, and cysplatin. Age represented the main risk factor for PN (p=0.036) with an increase in risk of PN amounting to 6% per year of age. In conclusion, incidence, severity and outcome of bortezomib-related PN are similar in untreated and pre-treated MM patients except for neuropathic pain which has lower incidence and shorter duration in untreated patients with less frequent need for bortezomib discontinuation. Age emerges as the most relevant risk factor for peripheral neuropathy, with a risk increase for PN of 6% per year of age.

Immune-mediated neuropathies in myeloma patients treated with bortezomib.

OBJECTIVE Bortezomib is a new chemotherapeutic drug available for the treatment of lymphoid disorders, including multiple myeloma. Although its primary mechanism of action is proteasome inhibition, other mechanisms can contribute to the therapeutic effects, including modulation of inflammatory cytokines and immune response. One of the main toxic effects of bortezomib is peripheral neuropathy, usually occurring in the form of a painful, sensory axonal neuropathy. The mechanisms of peripheral damage, however, are still unclear. We here report a series of patients treated with bortezomib, who developed a peripheral damage possibly related to immuno-mediated, rather than toxic, mechanisms. METHODS Five patients who developed a peripheral neuropathy with severe motor involvement under bortezomib treatment underwent CSF, electrophysiological, and spinal cord MRI examinations. RESULTS Peripheral damage was characterized by: demyelinating or mixed axonal-demyelinating neuropathy, with prominent motor involvement; albumin-cytological dissociation; lumbar root enhancement on MRI in 2/5 patients; favourable outcome in 4/5 patients after immune treatments, either steroids (2 patients) or IVIg (2 patients). CONCLUSIONS In some instances, the peripheral damage associated with bortezomib may recognize immuno-mediated mechanisms. SIGNIFICANCE This form of bortezomib-associated neuropathy needs to be recognized as treatable condition, as it may respond to immune therapies. Unexplained worsening of neurological dysfunction despite bortezomib discontinuation, with prominent motor involvement and CSF signs of inflammation, may be the clues to this complication.

Zoledronic acid down-regulates adhesion molecules of bone marrow stromal cells in multiple myeloma : A possible mechanism for its antitumor effect

Myeloma plasma cells interact with the bone marrow microenvironment which, in turn, supports their growth and protects them from apoptosis. In vitro studies have demonstrated the antitumor potential of zoledronic acid (ZOL) on myeloma cell lines, but few data are available on its effects on bone marrow stromal cells (BMSCs). The aim of the current study was to evaluate the antiproliferative and apoptotic effect of ZOL on BMSCs, as well as its effect on the expression of adhesion molecules.

Clonal architecture of CXCR4 WHIM-like mutations in Waldenström Macroglobulinaemia

CXCR4WHIM somatic mutations are distinctive to Waldenström Macroglobulinaemia (WM), and impact disease presentation and treatment outcome. The clonal architecture of CXCR4WHIM mutations remains to be delineated. We developed highly sensitive allele‐specific polymerase chain reaction (AS‐PCR) assays for detecting the most common CXCR4WHIM mutations (CXCR4S338X C>A and C>G) in WM. The AS‐PCR assays detected CXCR4S338X mutations in WM and IgM monoclonal gammopathy of unknown significance (MGUS) patients not revealed by Sanger sequencing. By combined AS‐PCR and Sanger sequencing, CXCR4WHIM mutations were identified in 44/102 (43%), 21/62 (34%), 2/12 (17%) and 1/20 (5%) untreated WM, previously treated WM, IgM MGUS and marginal zone lymphoma patients, respectively, but no chronic lymphocytic leukaemia, multiple myeloma, non‐IgM MGUS patients or healthy donors. Cancer cell fraction analysis in WM and IgM MGUS patients showed CXCR4S338X mutations were primarily subclonal, with highly variable clonal distribution (median 35·1%, range 1·2–97·5%). Combined AS‐PCR and Sanger sequencing revealed multiple CXCR4WHIM mutations in many individual WM patients, including homozygous and compound heterozygous mutations validated by deep RNA sequencing. The findings show that CXCR4WHIM mutations are more common in WM than previously revealed, and are primarily subclonal, supporting their acquisition after MYD88L265P in WM oncogenesis. The presence of multiple CXCR4WHIM mutations within individual WM patients may be indicative of targeted CXCR4 genomic instability.