The ETO2 transcriptional cofactor maintains acute leukemia by driving a MYB/EP300‐dependent stemness program

Transcriptional cofactors of the ETO family are recurrent fusion partners in acute leukemia. We characterized the ETO2 regulome by integrating transcriptomic and chromatin binding analyses in human erythroleukemia xenografts and controlled ETO2 depletion models. We demonstrate that beyond its well‐established repressive activity, ETO2 directly activates transcription of MYB, among other genes. The ETO2‐activated signature is associated with a poorer prognosis in erythroleukemia but also in other acute myeloid and lymphoid leukemia subtypes. Mechanistically, ETO2 colocalizes with EP300 and MYB at enhancers supporting the existence of an ETO2/MYB feedforward transcription activation loop (e.g., on MYB itself). Both small‐molecule and PROTAC‐mediated inhibition of EP300 acetyltransferases strongly reduced ETO2 protein, chromatin binding, and ETO2‐activated transcripts. Taken together, our data show that ETO2 positively enforces a leukemia maintenance program that is mediated in part by the MYB transcription factor and that relies on acetyltransferase cofactors to stabilize ETO2 scaffolding activity

Single-cell multi-omics identifies chronic inflammation as a driver of TP53-mutant leukemic evolution

Understanding the genetic and nongenetic determinants of tumor protein 53 (TP53)-mutation-driven clonal evolution and subsequent transformation is a crucial step toward the design of rational therapeutic strategies. Here we carry out allelic resolution single-cell multi-omic analysis of hematopoietic stem/progenitor cells (HSPCs) from patients with a myeloproliferative neoplasm who transform to TP53-mutant secondary acute myeloid leukemia (sAML). All patients showed dominant TP53 ‘multihit’ HSPC clones at transformation, with a leukemia stem cell transcriptional signature strongly predictive of adverse outcomes in independent cohorts, across both TP53-mutant and wild-type (WT) AML. Through analysis of serial samples, antecedent TP53-heterozygous clones and in vivo perturbations, we demonstrate a hitherto unrecognized effect of chronic inflammation, which suppressed TP53 WT HSPCs while enhancing the fitness advantage of TP53-mutant cells and promoted genetic evolution. Our findings will facilitate the development of risk-stratification, early detection and treatment strategies for TP53-mutant leukemia, and are of broad relevance to other cancer types

Intérêt de la recherche de la mutation MPL dans les thrombocytémies essentielles

PARIS7-Xavier Bichat (751182101) / SudocSudocFranceF

Mature CD8 + T-cell clonal expansion in the oral cavity and digestive tract: a severe lymphoid malignancy that mimics Crohn's disease

International audienceMature digestive CD8+ T-cell lymphomas are rare entities of variable severity (from indolent to aggressive and destructive disease) [1-3]. Despite their severity, their prognosis may be favorable if adapted treatment is provided [1]. We report here an unusual case of severe mature CD8+ T-cell lymphoma with digestive infiltration that mimicked Crohn's disease, but with favorable outcome upon oral treatment with cyclophosphamide

Hepatic nodular lymphoid lesion with increased IgG4-positive plasma cells associated with primary biliary cirrhosis: a report of two cases

International audienceThe nodular lymphoid lesion of the liver known as reactive lymphoid hyperplasia or pseudolymphoma is rare and its pathogenesis is unknown. We report two cases of nodular lymphoid lesions of the liver with numerous IgG4-positive plasma cells in patients with primary biliary cirrhosis. Histologically, in both cases, the lesion showed a dense lymphoplasmacytic infiltrate with lymphoid follicles and granulomas. Fibrous tissue was scarce and without a storiform pattern. Obliterative phlebitis was not identified. The IgG4+ plasma cell counts were 82 and 76 per high power field, with an IgG4/IgG ratio of 75 and 64 %, respectively, which qualifies the lesions according to the diagnostic criteria for IgG4-related disease as « probable histological feature of IgG4-related disease ». There were no rearrangements of immunoglobulin heavy-chain genes and plasma cells had a polytypic pattern of kappa and lambda light-chain expression. The non-tumor liver showed primary biliary cirrhosis with destructive cholangitis without IgG4 plasma cells. In both cases, IgG4-related disease was not found in other organs neither at the time of diagnosis nor 3 years later. Serum IgG4 levels normalized after local ablation of the lesions. It seems unlikely that these lesions are a manifestation of IgG4-related disease. However, because the pathogenesis of both nodular lymphoid lesions and IgG4-related disease remains unclear, further studies are needed to elucidate a potential link between nodular lymphoid lesions of the liver and an increased number of IgG4 plasma cells. More definite conclusions will be possible when the pathogenesis of IgG4-related disease has been clarified

A Web-Based Delphi Study for Eliciting Helpful Criteria in the Positive Diagnosis of Hemophagocytic Syndrome in Adult Patients

International audienceThe diagnosis of the reactive form of hemophagocytic syndrome in adults remains particularly difficult since none of the clinical or laboratory manifestations are specific. We undertook a study in order to elicit which features constitute helpful criteria for a positive diagnosis. In this Delphi study, the features investigated in the questionnaire and the experts invited to participate in the survey were issued from a bibliographic search. The questionnaire was iteratively proposed to experts via a web-based application with a feedback of the results observed at the preceding Delphi round. Experts were asked to label each investigated criterion in one of the following categories: absolutely required, important, of minor interest, or not assessable in the routine practice environment. A positive consensus was a priori defined as at least 75% answers observed in the categories absolutely required and important. The questionnaire investigated 26 criteria and 24 experts originating from 13 countries participated in the second and final Delphi round. A positive consensus was reached for the nine following criteria: unilineage cytopenia, bicytopenia, pancytopenia, presence of hemophagocytosis pictures on a bone marrow aspirate or on a tissue biopsy, high ferritin level, fever, organomegaly, presence of a predisposing underlying disease, and high level of lactate dehydrogenase. A negative consensus was reached for 13 criteria, and an absence of consensus was observed for 4 criteria. The study constitutes the first initiative to date for defining international guidelines devoted to the positive diagnosis of the reactive form of hemophagocytic syndrome

The Spectrum of Chronic CD8 T-Cell Expansions: Clinical Features in 14 Patients

International audienceChronic CD8 + T-cell expansions can result in parotid gland swelling and other organ infiltration in HIV-infected patients, or in persistent cytopenias. We report 14 patients with a CD8 + T-cell expansion to better characterize the clinical spectrum of this ill-defined entity. Patients (9 women/5 men) were 65 year-old (range, 25–74). Six patients had $1 symptomatic organ infiltration, and 9 had$1 cytopenia with a CD8 + (.50% of total lymphocyte count) and/or a CD8 + /CD57 + (.30% of total lymphocyte count) T-cell expansion for at least 3 months. One patient had both manifestations. A STAT3 mutation, consistent with the diagnosis of large granular lymphocyte leukemia, was found in 2 patients with cytopenia. Organ infiltration involved lymph nodes, the liver, the colon, the kidneys, the skin and the central nervous system. Three patients had a HIV infection for 8 years (range, 0.5–20 years). Two non-HIV patients with hypogammaglobulinemia had been treated with a B-cell depleting monoclonal antibody (rituximab) for a lymphoma. One patient had a myelodysplastic syndrome with colon infiltration and agranulocytosis. The outcome was favorable with efficient antiretroviral therapy and steroids in HIV-infected patients and intravenous immunoglobulins in 2/3 non-HIV patients. Six patients had an agranulocytosis of favorable outcome with granulocyte-colony stimulating factor only (3 cases), cyclophosphamide, methotrexate and cyclosporine A, or no treatment (1 case each). Three patients had a pure red cell aplasia, of favorable outcome in 2 cases with methotrexate and cyclosporine A; one patient was unresponsive. Chronic CD8 + T-cell expansions with organ infiltration in immunocompromised patients may involve other organs than parotid glands; they are non clonal and of favorable outcome after correction of the immune deficiency and/or steroids. In patients with bone marrow infiltration and unexplained cytopenia, CD8 + T-cell expansions can be clonal or not; their identification suggests that cytopenias are immune-mediated. Our results extend the clinical spectrum of chronic CD8 + T-cell expansions

Impact of interferon on a triple positive polycythemia vera

International audienceKey Points PF4iCre;JAK2 V617F/WT mice develop a full MPN that mimics polycythemia vera. The PF4iCre system induces JAK2V617F mutation in a small subset of HSC

Distribution of the answers at the second and last Delphi round.

<p>*Letters A, B, C, D, or E are codes corresponding to the following answers: A, absolutely required; B, important; C, of minor interest; D, useless; E, not assess(ed/able) in my routine practice environment.</p>‡<p>Choice of answer E was unavailable, absent from the menu list of answers.</p