Theo de Witte

Acquired mutations in TET2 are common in myelodysplastic syndromes

Myelodysplastic syndromes (MDS) represent a heterogeneous group of neoplastic hematopoietic disorders. Several recurrent chromosomal aberrations have been associated with MDS, but the genes affected have remained largely unknown. To identify relevant genetic lesions involved in the pathogenesis of MDS, we conducted SNP array–based genomic profiling and genomic sequencing in 102 individuals with MDS and identified acquired deletions and missense and nonsense mutations in the TET2 gene in 26% of these individuals. Using allele-specific assays, we detected TET2 mutations in most of the bone marrow cells (median 96%). In addition, the mutations were encountered in various lineages of differentiation including CD34+ progenitor cells, suggesting that TET2 mutations occur early during disease evolution. In healthy tissues, TET2 expression was shown to be elevated in hematopoietic cells with highest expression in granulocytes, in line with a function in myelopoiesis. We conclude that TET2 is the most frequently mutated gene in MDS known so far.

Somatic mutations of the histone methyltransferase gene EZH2 in myelodysplastic syndromes

In myelodysplastic syndromes (MDS), deletions of chromosome 7 or 7q are common and correlate with a poor prognosis. The relevant genes on chromosome 7 are unknown. We report here that EZH2, located at 7q36.1, is frequently targeted in MDS. Analysis of EZH2 deletions, missense and frameshift mutations strongly suggests that EZH2 is a tumor suppressor. As EZH2 functions as a histone methyltransferase, abnormal histone modification may contribute to epigenetic deregulation in MDS.

Diagnosis and treatment of primary myelodysplastic syndromes in adults: recommendations from the European LeukemiaNet

Within the myelodysplastic syndrome (MDS) work package of the European LeukemiaNet, an Expert Panel was selected according to the framework elements of the National Institutes of Health Consensus Development Program. A systematic review of the literature was performed that included indexed original papers, indexed reviews and educational papers, and abstracts of conference proceedings. Guidelines were developed on the basis of a list of patient- and therapy-oriented questions, and recommendations were formulated and ranked according to the supporting level of evidence. MDSs should be classified according to the 2008 World Health Organization criteria. An accurate risk assessment requires the evaluation of not only disease-related factors but also of those related to extrahematologic comorbidity. The assessment of individual risk enables the identification of fit patients with a poor prognosis who are candidates for up-front intensive treatments, primarily allogeneic stem cell transplantation. A high proportion of MDS patients are not eligible for potentially curative treatment because of advanced age and/or clinically relevant comorbidities and poor performance status. In these patients, the therapeutic intervention is aimed at preventing cytopenia-related morbidity and preserving quality of life. A number of new agents are being developed for which the available evidence is not sufficient to recommend routine use. The inclusion of patients into prospective clinical trials is strongly recommended.

Risk Score for Outcome After Allogeneic Hematopoietic Stem Cell Transplantation: A Retrospective Analysis

It was investigated whether the European Group for Blood and Marrow Transplantation risk score, previously established for chronic myeloid leukemia, could be used to predict outcome after allogeneic hematopoietic stem cell transplantation (HSCT) for hematological disease in general.

Allogeneic stem cell transplantation after reduced-intensity conditioning in patients with myelofibrosis: a prospective, multicenter study of the Chronic Leukemia Working Party of the European Group for Blood and Marrow Transplantation.

From 2002 to 2007, 103 patients with primary myelofibrosis or postessential thrombocythemia and polycythemia vera myelofibrosis and a median age of 55 years (range, 32-68 years) were included in a prospective multicenter phase 2 trial to determine efficacy of a busulfan (10 mg/kg)/fludarabine (180 mg/m(2))-based reduced-intensity conditioning regimen followed by allogeneic stem cell transplantation from related (n = 33) or unrelated donors (n = 70). All but 2 patients (2%) showed leukocyte and platelet engraftment after a median of 18 and 22 days, respectively. Acute graft-versus-host disease grade 2 to 4 occurred in 27% and chronic graft-versus-host disease in 43% of the patients. Cumulative incidence of nonrelapse mortality at 1 year was 16% (95% confidence interval, 9%-23%) and significantly lower for patients with a completely matched donor (12% vs 38%; P = .003). The cumulative incidence of relapse at 3 years was 22% (95% confidence interval, 13%-31%) and was influenced by Lille risk profile (low, 14%; intermediate, 22%; and high, 34%; P = .02). The estimated 5-year event-free and overall survival was 51% and 67%, respectively. In a multivariate analysis, age older than 55 years (hazard ratio = 2.70; P = .02) and human leukocyte antigen-mismatched donor (hazard ratio = 3.04; P = .006) remained significant factors for survival. The study was registered at www.clinicaltrials.gov as #NCT 00599547.

Haematopoietic stem cell transplantation for patients with myelo- dysplastic syndromes and secondary acute myeloid leukaemias: a report on behalf of the Chronic Leukaemia Working Party of the European Group for Blood and Marrow Transplantation (EBMT)

Allogeneic stem cell transplantation from an HLA‐identical sibling donor is a curative treatment option for a young patient with myelodysplastic syndrome, limited by age and lack of sibling donors. Alternative stem cell sources have been used more recently, such as unrelated donors, non‐identical family members or autologous transplants. This analysis of 1378 transplants reported to the European Group for Blood and Marrow Transplantation (EBMT) addresses the outcome of the varying procedures according to the known risk factors. The estimated disease‐free survival (DFS) and estimated relapse risk at 3 years were both 36% for 885 patients transplanted with stem cells from matched siblings. In the multivariate analysis, age and stage of disease had independent prognostic significance for DFS, survival and treatment‐related mortality. Patients transplanted at an early stage of disease had a significantly lower risk of relapse than patients transplanted at more advanced stages. The estimated DFS at 3 years was 25% for the 198 patients with voluntary unrelated donors, 28% for the 91 patients with alternative family donors and 33% for the 126 patients autografted in first complete remission. The non‐relapse mortality was 58% for patients with unrelated donors, 66% for patients with non‐identical family donors and 25% for autografted patients. The relapse rate of 18% was relatively low for patients with non‐identical family donors, 41% for patients with unrelated donors and 55% for patients treated with autologous stem cell transplantation. Both allogeneic and autologous stem cell transplantation have emerged as treatment options for patients with myelodysplastic syndromes. Transplantation with an HLA‐identical sibling donor is the preferred treatment option. Patients without an HLA‐identical sibling donor may be treated with either autologous stem cell transplantation or an alternative donor transplantation. Patients younger than 20 years may be treated with an unrelated donor transplantation. Patients older than 40 years, and probably also patients between 20 and 40 years, may benefit most from an autologous stem cell transplantation.

Allogeneic Hematopoietic Stem-Cell Transplantation for Patients 50 Years or Older With Myelodysplastic Syndromes or Secondary Acute Myeloid Leukemia

PURPOSE This study was performed to examine the characteristics of transplant activity for patients with myelodysplastic syndromes (MDS) older than 50 years within the European Group for Blood and Marrow Transplantation, and to evaluate the factors predicting outcome within this group of patients. PATIENTS AND METHODS We performed a retrospective multicenter analysis of 1,333 MDS patients age 50 years or older who received transplantation within the EBMT since 1998. The median recipient age was 56 years, with 884 patients (66%) age 50 to 60 years and 449 (34%) patients older than 60 years. There were 811 HLA-matched sibling (61%) and 522 (39%) unrelated donor transplants. Five hundred patients (38%) received standard myeloablative conditioning (SMC), and 833 (62%) received reduced intensity conditioning (RIC). RESULTS The 4-year estimate for overall survival of the whole cohort was 31%. On multivariate analysis, use of RIC (hazard ratio [HR], 1.44; 95% CI, 1.13 to 1.84; P < .01) and advanced disease stage at transplantation (HR, 1.51; 95% CI, 1.18 to 1.93; P < .01) were associated with an increased relapse rate. In contrast, advanced disease stage at transplantation (HR, 1.43; 95% CI, 1.13 to 1.79; P = .01), use of an unrelated donor (P = .03), and RIC (HR, 0.79; 95% CI, 0.65 to 0.97; P = .03) were independent variables associated with nonrelapse mortality. Advanced disease stage at transplantation (HR, 1.55; 95% CI, 1.32 to 1.83; P < .01) was the major independent variable associated with an inferior 4-year overall survival. CONCLUSION Allogeneic hematopoietic stem-cell transplantation remains a potential curative therapeutic option for many older patients with MDS. In this analysis, disease stage at time of transplantation, but not recipient age or the intensity of the conditioning regimens, was the most important factor influencing outcomes.

Standardization of flow cytometry in myelodysplastic syndromes: report from the first European LeukemiaNet working conference on flow cytometry in myelodysplastic syndromes

This article decribes the results of the first European LeukemiaNet working conference on flow cytometry immunophenotyping in myelodysplastic syndrome. This report is a very comprehensive analysis of the topic, and provides detailed information on what is currently known in the field. See related perspective article on page 1041. The myelodysplastic syndromes are a group of clonal hematopoietic stem cell diseases characterized by cytopenia(s), dysplasia in one or more cell lineages and increased risk of evolution to acute myeloid leukemia (AML). Recent advances in immunophenotyping of hematopoietic progenitor and maturing cells in dysplastic bone marrow point to a useful role for multiparameter flow cytometry (FCM) in the diagnosis and prognostication of myelodysplastic syndromes. In March 2008, representatives from 18 European institutes participated in a European LeukemiaNet (ELN) workshop held in Amsterdam as a first step towards standardization of FCM in myelodysplastic syndromes. Consensus was reached regarding standard methods for cell sampling, handling and processing. The group also defined minimal combinations of antibodies to analyze aberrant immunophenotypes and thus dysplasia. Examples are altered numbers of CD34+ precursors, aberrant expression of markers on myeloblasts, maturing myeloid cells, monocytes or erythroid precursors and the expression of lineage infidelity markers. When applied in practice, aberrant FCM patterns correlate well with morphology, the subclassification of myelodysplastic syndromes, and prognostic scoring systems. However, the group also concluded that despite strong evidence for an impact of FCM in myelodysplastic syndromes, further (prospective) validation of markers and immunophenotypic patterns are required against control patient groups as well as further standardization in multi-center studies. Standardization of FCM in myelodysplastic syndromes may thus contribute to improved diagnosis and prognostication of myelodysplastic syndromes in the future.

Allogeneic Hematopoietic Stem-Cell Transplantation for Chronic Lymphocytic Leukemia With 17p Deletion: A Retrospective European Group for Blood and Marrow Transplantation Analysis

PURPOSE Patients with chronic lymphocytic leukemia (CLL) and 17p deletion (17p-) have a poor prognosis. Although allogeneic hematopoietic stem-cell transplantation (HCT) has the potential to cure patients with advanced CLL, it is not known whether this holds true for patients with 17p-CLL. PATIENTS AND METHODS Baseline data from patients, for whom information on the presence of 17p-CLL was available, were downloaded from the European Group for Blood and Marrow Transplantation database. Additional information on the course of CLL and follow-up was collected with a questionnaire. RESULTS A total of 44 patients with 17p-CLL received allogeneic HCT between March 1995 and July 2006 from a matched sibling (n = 24) or an alternative donor (n = 20). 17p-CLL had been diagnosed by fluorescent in situ hybridization in 82% of patients and by conventional banding in 18% of patients. The median age was 54 years. Before HCT, a median of three lines of chemotherapy had been administered. At HCT, 53% of patients were in remission. Reduced-intensity conditioning was applied in 89% of patients. Acute, grade 2 to 4 graft-versus-host disease (GVHD) occurred in 43% of patients, and extensive chronic GVHD occurred in 53% of patients. At last follow-up, 19 patients were alive, with a median observation time of 39 months (range, 18 to 101 months). Three-year overall survival and progression-free survival rates were 44% and 37%, respectively. The cumulative incidence of progressive disease at 4 years was 34%. No late relapse occurred in nine patients with a follow-up longer than 4 years. CONCLUSION Allogeneic HCT has the potential to induce long-term disease-free survival in patients with 17p-CLL.

Midostaurin plus Chemotherapy for Acute Myeloid Leukemia with a FLT3 Mutation

Background Patients with acute myeloid leukemia (AML) and a FLT3 mutation have poor outcomes. We conducted a phase 3 trial to determine whether the addition of midostaurin — an oral multitargeted kinase inhibitor that is active in patients with a FLT3 mutation — to standard chemotherapy would prolong overall survival in this population. Methods We screened 3277 patients, 18 to 59 years of age, who had newly diagnosed AML for FLT3 mutations. Patients were randomly assigned to receive standard chemotherapy (induction therapy with daunorubicin and cytarabine and consolidation therapy with high‐dose cytarabine) plus either midostaurin or placebo; those who were in remission after consolidation therapy entered a maintenance phase in which they received either midostaurin or placebo. Randomization was stratified according to subtype of FLT3 mutation: point mutation in the tyrosine kinase domain (TKD) or internal tandem duplication (ITD) mutation with either a high ratio (>0.7) or a low ratio (0.05 to 0.7) of mutant to wild‐type alleles (ITD [high] and ITD [low], respectively). Allogeneic transplantation was allowed. The primary end point was overall survival. Results A total of 717 patients underwent randomization; 360 were assigned to the midostaurin group, and 357 to the placebo group. The FLT3 subtype was ITD (high) in 214 patients, ITD (low) in 341 patients, and TKD in 162 patients. The treatment groups were well balanced with respect to age, race, FLT3 subtype, cytogenetic risk, and blood counts but not with respect to sex (51.7% in the midostaurin group vs. 59.4% in the placebo group were women, P=0.04). Overall survival was significantly longer in the midostaurin group than in the placebo group (hazard ratio for death, 0.78; one‐sided P=0.009), as was event‐free survival (hazard ratio for event or death, 0.78; one‐sided P=0.002). In both the primary analysis and an analysis in which data for patients who underwent transplantation were censored, the benefit of midostaurin was consistent across all FLT3 subtypes. The rate of severe adverse events was similar in the two groups. Conclusions The addition of the multitargeted kinase inhibitor midostaurin to standard chemotherapy significantly prolonged overall and event‐free survival among patients with AML and a FLT3 mutation. (Funded by the National Cancer Institute and Novartis; ClinicalTrials.gov number, NCT00651261.)