BACKGROUND Cancers result from the accumulation of somatic mutations, and their properties are thought to reflect the sum of these mutations. However, little is known about the effect of the order in which mutations are acquired. METHODS We determined mutation order in patients with myeloproliferative neoplasms by genotyping hematopoietic colonies or by means of next-generation sequencing. Stem cells and progenitor cells were isolated to study the effect of mutation order on mature and immature hematopoietic cells. RESULTS The age at which a patient presented with a myeloproliferative neoplasm, acquisition of JAK2 V617F homozygosity, and the balance of immature progenitors were all influenced by mutation order. As compared with patients in whom the TET2 mutation was acquired first (hereafter referred to as “TET2-first patients”), patients in whom the Janus kinase 2 (JAK2) mutation was acquired first (“JAK2-first patients”) had a greater likelihood of presenting with polycythemia vera than with essential thrombocythemia, an increased risk of thrombosis, and an increased sensitivity of JAK2-mutant progenitors to ruxolitinib in vitro. Mutation order influenced the proliferative response to JAK2 V617F and the capacity of double-mutant hematopoietic cells and progenitor cells to generate colony-forming cells. Moreover, the hematopoietic stem-and-progenitor-cell compartment was dominated by TET2 single-mutant cells in TET2-first patients but by JAK2–TET2 double-mutant cells in JAK2-first patients. Prior mutation of TET2 altered the transcriptional consequences of JAK2 V617F in a cell-intrinsic manner and prevented JAK2 V617F from up-regulating genes associated with proliferation. CONCLUSIONS The order in which JAK2 and TET2 mutations were acquired influenced clinical features, the response to targeted therapy, the biology of stem and progenitor cells, and clonal evolution in patients with myeloproliferative neoplasms. (Funded by Leukemia and Lymphoma Research and others.)

SUMMARY It was previously shown that the NF-κB pathway is downstream of oncogenic Notch1 in T cell acute lymphoblastic leukemia (T-ALL). Here we visualize Notch-induced NF-κB activation using both human T-ALL cell lines and animal models. We demonstrate that Hes1, a canonical Notch target and transcriptional repressor, is responsible for sustaining IKK activation in T-ALL. Hes1 exerts its effects by repressing the deubiquitinase CYLD, a negative IKK complex regulator. CYLD expression was found to be significantly suppressed in primary T-ALL. Finally, we demonstrate that IKK inhibition is a promising option for the targeted therapy of T-ALL as specific suppression of IKK expression and function affected both the survival of human T-ALL cells and the maintenance of the disease in vivo.

Criteria of response and definition of resistance and intolerance to hydroxyurea (HU) in polycythemia vera (PV) were proposed by the European LeukemiaNet (ELN). Such criteria were evaluated in 261 PV patients (median follow-up, 7.2 years) treated with HU for a median of 4.4 years. Complete response, partial response, and no response were observed in 24%, 66%, and 10% of patients, respectively. Achieving ELN response (complete or partial) or hematocrit response did not result in better survival or less thrombosis and bleeding. On the contrary, having no response in leukocyte count was associated with higher risk of death (HR, 2.7; 95% confidence interval [CI], 1.3%-5.4%; P ‫؍‬ .007), whereas lack of response in platelet count involved a higher risk of thrombosis and bleeding. Resistance and intolerance to HU was registered in 11% and 13% of patients, respectively. Resistance to HU was associated with higher risk of death (HR, 5.6; 95% CI, 2.7%-11.9%; P < .001) and transformation (HR, 6.8; 95% CI, 3.0%-15.4%; P < .001). In summary, fulfilling the ELN definition for response to HU was not associated with a benefit in the clinical outcome in PV, whereas response in platelet and white blood cell counts were predictive of less thrombohemorrhagic complications and better prognosis, respectively. Resistance to HU was an adverse prognostic factor. (Blood. 2012;119(6):1363-1369)

Although approximately 95% of patients with polycythemia vera (PV) harbor the V617F mutation in JAK2 exon 14, several mutations in exon 12 have been described in the remaining patients. We conducted a European collaborative study to define the molecular and clinical features of patients harboring these mutations. Overall, 106 PVs were recruited and 17 different mutations identified. Irrespective of the mutation, two-thirds of patients had isolated erythrocytosis, whereas the remaining subjects had erythrocytosis plus leukocytosis and/or thrombocytosis. Compared with JAK2 (V617F)-positive PV patients, those with exon 12 mutations had significantly higher hemoglobin level and lower platelet and leukocyte counts at diagnosis but similar incidences of thrombosis, myelofibrosis, leukemia, and death. In a multivariable analysis, age more than 60 years and prior thrombosis predicted thrombosis. These findings suggest that, despite the phenotypical difference, the outcome of JAK2 exon 12 mutations-positive PV is similar to that of JAK2 (

Summary. In this report we analyse the presenting features of a series of patients diagnosed with Waldenstro Èm macroglobulinaemia (WM) in Spain over the last 10 years. Criteria for diagnosis required a serum monoclonal IgM protein > 30 g/l and . 20% bone marrow lymphocytes. Two hundred and seventeen patients were included in the study, with a median age of 69 years and male/female ratio of 2:1. The most common symptoms at diagnosis were anaemia (38%), hyperviscosity (31%), B symptoms (23%), bleeding (23%) and neurological symptoms (22%). Sixty-one patients (27%) were asymptomatic at diagnosis and, to date, 32 of them have not received chemotherapy. Variables predicting a shorter survival free of therapy were haemoglobin , 12´5 g/dl and high b 2 microglobulin (b2M). The 83% of patients who did receive treatment were distributed as follows: chlorambucil/prednisone (43%), intermittent chlorambucil (11%), continuous chlorambucil (26%), cyclophosphamide/vincristine/ prednisone (COP, 13´5%) and other (6´5%). Response to therapy was complete in 2%, partial in 48% and minor in 10%. Finally, 28% and 13% of patients presented stable and progressive disease, respectively, which was more common among patients treated with COP. Progression-free survival was 43% at 5 years, with three independent predictors for shorter progression-free survival (PFS): COP treatment, age . 65 and B symptoms at diagnosis. The 10-year projected overall survival (OS) was 55%. The two most frequent causes of death were development of second malignancies (31%), or infections (19%). The two main variables predicting a poor OS were hyperviscosity and high b2M. In summary, this study favours the use of chlorambucil-based therapy as the standard treatment for WM, and describes a subset of patients who should be considered as suffering a smouldering form and who therefore do not require treatment for a long period of time.

The frequency of vascular events and evolution to myelofibrosis (MF) in young individuals with essential thrombocythemia (ET) is not well known. The incidence and predisposing factors to such complications was studied in 126 subjects diagnosed with ET at a median age of 31 years (range: 5-40). Overall survival and probability of survival free of thrombosis, bleeding and MF were analyzed by the Kaplan-Meier method and the presence of the Janus Kinase 2 (JAK2) V617F mutation correlated with the appearance of such complications. The JAK2 mutation (present in 43% of patients) was associated with higher hemoglobin (Hb) (Po0.001) and lower platelets at diagnosis. With a median follow-up of 10 years (range: 4-25), 31 thrombotic events were registered (incidence rate: 2.2 thromboses/100 patients/year). When compared with the general population, young ET patients showed a significant increase in stroke (odds ratio 50, 95% CI: 21.5-115) and venous thromboses (odds ratio 5.3, 95% CI: 3.9-10.6). Thrombosis-free survival was 84% at 10 years, with tobacco use being associated with higher risk of thrombosis. Actuarial freedom from evolution to MF was 97% at 10 years. In conclusion, young ET patients have thrombotic events, especially stroke and venous thrombosis, more frequently than generally considered, whereas they rarely transform to MF.

Summary Standardized criteria of response to treatment and a unified definition of resistance/intolerance to hydroxycarbamide (HC) in essential thrombocythaemia (ET) have been proposed by the European LeukaemiaNet (ELN). We have retrospectively evaluated such criteria in 166 ET patients treated with HC for a median of 4·5 years. Overall, 134 patients achieved a complete clinicohaematological response (CR) and 25 a partial response. Thirty‐three patients met at least one of the ELN criteria defining resistance (n = 15) or intolerance (n = 21) to HC. Fifteen cases developed anaemia with thrombocytosis, which was associated with a high incidence of myelofibrosis and death from any cause. Other definitions of resistance were less useful. Factors determining the thrombotic risk were a history of prior thrombosis and a baseline leucocyte count >10 × 109/l. Of note, patients achieving a CR, even if sustained during the entire follow‐up, did not benefit from a lower incidence of thrombosis or an improved survival. In conclusion, most ET patients respond to HC, but the achievement of response, as defined by the ELN, does not correlate with the patients’ outcome. The best discriminating ELN criterion of resistance to HC was the detection of anaemia, which also identified a subgroup of patients with poor prognosis.

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