0000000000115790
AUTHOR
Torsten Haferlach
EZH2 mutations are frequent and represent an early event in follicular lymphoma
Gain of function mutations in the H3K27 methyltransferase EZH2 represent a promising therapeutic target in germinal center lymphomas. In this study, we assessed the frequency and distribution of EZH2 mutations in a large cohort of patients with follicular lymphoma (FL) (n = 366) and performed a longitudinal analysis of mutation during the disease progression from FL to transformed FL (tFL) (n = 33). Mutations were detected at 3 recurrent mutation hot spots (Y646, A682, and A692) in 27% of FL cases with variant allele frequencies (VAF) ranging from 2% to 61%. By comparing VAF of EZH2 with other mutation targets (CREBBP, MLL2, TNFRSF14, and MEF2B), we were able to distinguish patients harbori…
Outcome of Refractory Anemia with Ringed Sideroblasts Associated with Marked Thrombocytosis (RARS-T) In a Large Cohort of Patients
Abstract Abstract 4113 Introduction: Most of the data related to RARS-T, a rare disorder, involve small cohorts of patients. We aimed to analyze more patients also considering a variety of myelodysplastic or myeloproliferative disorders. Objective: To compare a large cohort of patients with RARS-T to refractory anemia with ringed sideroblasts (RARS), refractory anemia with ringed sideroblasts and multilineage dysplasia (RARS-MD) or essential thrombocythemia (ET) at the time of diagnosis and during disease evolution, in terms of survival and complications. Materials: Data of a European multi-center study was used including 199 cases of RARS-T 173 cases of RARS, 102 cases of RARS-MD and 431 c…
Myeloid leukemia with transdifferentiation plasticity developing from T-cell progenitors
Unfavorable patient survival coincides with lineage plasticity observed in human acute leukemias. These cases are assumed to arise from hematopoietic stem cells, which have stable multipotent differentiation potential. However, here we report that plasticity in leukemia can result from instable lineage identity states inherited from differentiating progenitor cells. Using mice with enhanced c-Myc expression, we show, at the single-cell level, that T-lymphoid progenitors retain broad malignant lineage potential with a high capacity to differentiate into myeloid leukemia. These T-cell-derived myeloid blasts retain expression of a defined set of T-cell transcription factors, creating a lymphoi…
Genome-wide association study identifies novel susceptibility loci for KIT D816V positive mastocytosis
Mastocytosis is a rare myeloid neoplasm characterized by uncontrolled expansion of mast cells, driven in >80% of affected individuals by acquisition of the KIT D816V mutation. To explore the hypothesis that inherited variation predisposes to mastocytosis, we performed a two-stage genome-wide association study, analyzing 1,035 individuals with KIT D816V positive disease and 17,960 healthy control individuals from five European populations. After quality control, we tested 592,007 SNPs at stage 1 and 75 SNPs at stage 2 for association by using logistic regression and performed a fixed effects meta-analysis to combine evidence across the two stages. From the meta-analysis, we identified three …
Clinical Features And Course Of Refractory Anemia With Ring Sideroblasts Associated With Marked Thrombocytosis
Background Refractory anemia with ring sideroblasts associated with marked thrombocytosis was proposed as a provisional entity in the 2001 World Health Organization classification of myeloid neoplasms and also in the 2008 version, but its existence as a single entity is contested. We wish to define the clinical features of this rare myelodysplastic/myeloproliferative neoplasm and to compare its clinical outcome with that of refractory anemia with ring sideroblasts and essential thrombocythemia. Design and Methods We conducted a collaborative retrospective study across Europe. Our database included 200 patients diagnosed with refractory anemia with ring sideroblasts and marked thrombocytosis…
Sorafenib maintenance after allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia with FLT3-internal tandem duplication mutation (SORMAIN).
PURPOSE Despite undergoing allogeneic hematopoietic stem cell transplantation (HCT), patients with acute myeloid leukemia (AML) with internal tandem duplication mutation in the FMS-like tyrosine kinase 3 gene ( FLT3-ITD) have a poor prognosis, frequently relapse, and die as a result of AML. It is currently unknown whether a maintenance therapy using FLT3 inhibitors, such as the multitargeted tyrosine kinase inhibitor sorafenib, improves outcome after HCT. PATIENTS AND METHODS In a randomized, placebo-controlled, double-blind phase II trial (SORMAIN; German Clinical Trials Register: DRKS00000591), 83 adult patients with FLT3-ITD–positive AML in complete hematologic remission after HCT were r…
Identification of a novel type of ITD mutations located in nonjuxtamembrane domains of the FLT3 tyrosine kinase receptor
Abstract In acute myeloid leukemia (AML), internal tandem duplications (ITDs) of the juxtamembrane (JM) of FLT3 have been shown to play a crucial role in driving proliferation and survival of the leukemic clone. Here, we report the identification of FLT3_ITD mutations located in non-JM domains of the FLT3-receptor. This novel type of FLT3_ITD mutation was found in 216 of 753 (28.7%) of unselected FLT3_ITD-positive AML cases. An FLT3 receptor harbouring a prototypic non-JM ITD (FLT3_ITD627E) mediated constitutive phosphorylation of FLT3 and of STAT5, suggesting that non-JM ITDs confer constitutive activation of the receptor. FLT3_ITD627E induced transformation of hematopoietic 32D cells and …