Publications by authors named "Olivier Kosmider"

78 Publications

Oxidized mitochondrial DNA released after inflammasome activation is a disease biomarker for myelodysplastic syndromes.

Blood Adv 2021 Apr;5(8):2216-2228

Raleigh, NC.

Myelodysplastic syndromes (MDS) are heterogeneous hematopoietic stem cell malignancies that can phenotypically resemble other hematologic disorders. Thus, tools that may add to current diagnostic practices could aid in disease discrimination. Constitutive innate immune activation is a pathogenetic driver of ineffective hematopoiesis in MDS through Nod-like receptor protein 3 (NLRP3)-inflammasome-induced pyroptotic cell death. Oxidized mitochondrial DNA (ox-mtDNA) is released upon cytolysis, acts as a danger signal, and triggers inflammasome oligomerization via DNA sensors. By using immortalized bone marrow cells from murine models of common MDS somatic gene mutations and MDS primary samples, we demonstrate that ox-mtDNA is released upon pyroptosis. ox-mtDNA was significantly increased in MDS peripheral blood (PB) plasma compared with the plasma of healthy donors, and it was significantly higher in lower-risk MDS vs higher-risk MDS, consistent with the greater pyroptotic cell fraction in lower-risk patients. Furthermore, ox-mtDNA was significantly higher in MDS PB plasma compared with all other hematologic malignancies studied, with the exception of chronic lymphocytic leukemia (CLL). Receiver operating characteristic/area under the curve (ROC/AUC) analysis demonstrated that ox-mtDNA is a sensitive and specific biomarker for patients with MDS compared with healthy donors (AUC, 0.964), other hematologic malignancies excluding CLL (AUC, 0.893), and reactive conditions (AUC, 0.940). ox-mtDNA positively and significantly correlated with levels of known alarmins S100A9, S100A8, and apoptosis-associated speck-like protein containing caspase recruitment domain (CARD) specks, which provide an index of medullary pyroptosis. Collectively, these data indicate that quantifiable ox-mtDNA released into the extracellular space upon inflammasome activation serves as a biomarker for MDS and the magnitude of pyroptotic cell death.
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http://dx.doi.org/10.1182/bloodadvances.2020003475DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8095151PMC
April 2021

Myeloproliferative neoplasms and clonal hematopoiesis in patients with giant cell arteritis: a case-control and exploratory study.

Rheumatology (Oxford) 2021 Apr 9. Epub 2021 Apr 9.

Department of Internal Medicine, Cochin Hospital, National Referral Center for Rare Systemic Autoimmune Diseases, Paris University, Paris, France.

Objectives: Giant cell arteritis (GCA) is a large vessel vasculitis for which triggering factors remain unknown. Clonal hematopoiesis (CH) was associated with atherosclerosis through the induction of inflammation in myeloid cells, and data suggest that CH expansion and inflammation may support each other to induce a proinflammatory loop. Our objective was to describe the impact of JAK2p.V617F-mutated myeloproliferative neoplasms (MPN) on GCA and to screen MPN-free patients for CH mutations.

Methods: We performed a retrospective case-control study comparing characteristics of 21 GCA patients with MPN and 42 age and gender-matched GCA patients without MPN. Also, 18 GCA patients were screened for CH through Next Generation Sequencing.

Results: The most frequent associated MPN was essential thrombocythemia (ET) (n = 11). Compared to controls, GCA patients with MPN had less frequent cephalic symptoms (71.4 vs. 97.6%, p = 0.004) and higher platelets count at baseline [485 (346-586) vs. 346 [IQR 296-418] x 109/L, p = 0.02). There was no difference between groups for other clinical features. Overall survival was significantly shorter in patients with MPN compared to controls [HR 8.2 (95% CI 1.2-56.6), p = 0.03]. Finally, screening for CH using NGS in 15 GCA patients without MPN revealed CH in 33%.

Conclusion: GCA patients with MPN display higher platelets count and shorter overall survival than controls. This association could not be fortuitous given the possible pathophysiological relationship between the two diseases. CH was found in one third of GCA patients, which may be higher than the expected prevalence for similar age, what should be confirmed in a larger cohort.
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http://dx.doi.org/10.1093/rheumatology/keab337DOI Listing
April 2021

Severe Joint Involvement in VEXAS Syndrome: A Case Report.

Ann Intern Med 2021 Mar 30. Epub 2021 Mar 30.

Angers University Hospital, Angers, France.

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http://dx.doi.org/10.7326/L21-0023DOI Listing
March 2021

Genomic analysis of primary and secondary myelofibrosis redefines the prognostic impact of ASXL1 mutations: a FIM study.

Blood Adv 2021 Mar;5(5):1442-1451

Service d'Hématologie, CH Perpignan, Perpignan, France.

We aimed to study the prognostic impact of the mutational landscape in primary and secondary myelofibrosis. The study included 479 patients with myelofibrosis recruited from 24 French Intergroup of Myeloproliferative Neoplasms (FIM) centers. The molecular landscape was studied by high-throughput sequencing of 77 genes. A Bayesian network allowed the identification of genomic groups whose prognostic impact was studied in a multistate model considering transitions from the 3 conditions: myelofibrosis, acute leukemia, and death. Results were validated using an independent, previously published cohort (n = 276). Four genomic groups were identified: patients with TP53 mutation; patients with ≥1 mutation in EZH2, CBL, U2AF1, SRSF2, IDH1, IDH2, NRAS, or KRAS (high-risk group); patients with ASXL1-only mutation (ie, no associated mutation in TP53 or high-risk genes); and other patients. A multistate model found that both TP53 and high-risk groups were associated with leukemic transformation (hazard ratios [HRs] [95% confidence interval], 8.68 [3.32-22.73] and 3.24 [1.58-6.64], respectively) and death from myelofibrosis (HRs, 3.03 [1.66-5.56] and 1.77 [1.18-2.67], respectively). ASXL1-only mutations had no prognostic value that was confirmed in the validation cohort. However, ASXL1 mutations conferred a worse prognosis when associated with a mutation in TP53 or high-risk genes. This study provides a new definition of adverse mutations in myelofibrosis with the addition of TP53, CBL, NRAS, KRAS, and U2AF1 to previously described genes. Furthermore, our results argue that ASXL1 mutations alone cannot be considered detrimental.
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http://dx.doi.org/10.1182/bloodadvances.2020003444DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7948260PMC
March 2021

Reticulocytosis As a Whistleblower: A Rare Case of Acquired Elliptocytosis in a Myelodysplastic Syndrome Patient With Trisomy 8.

Hemasphere 2021 Feb 12;5(2):e517. Epub 2021 Jan 12.

Service d'Hématologie-Immunologie-Transfusion, Hôpitaux Universitaires Paris Ile De France Ouest, Université Versailles Saint Quentin-Paris-Saclay, Paris, France.

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http://dx.doi.org/10.1097/HS9.0000000000000517DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7806241PMC
February 2021

APR-246 induces early cell death by ferroptosis in acute myeloid leukemia.

Haematologica 2021 Jan 7. Epub 2021 Jan 7.

Université de Paris, Institut Cochin, CNRS UMR8104, INSERM U1016, Paris, France; Assistance Publique-Hôpitaux de Paris. Centre-Université de Paris, Service d'Hématologie clinique, Hôpital Cochin, Paris.

APR-246 is a promising new therapeutic agent that targets p53 mutated proteins in myelodysplastic syndromes and in acute myeloid leukemia. APR-246 reactivates the transcriptional activity of p53 mutants by facilitating their binding to DNA target sites. Recent studies in solid cancers have found that APR-246 can also induce p53-independent cell death. In this study, we demonstrate that AML cell death occurring early after APR-246 exposure is suppressed by iron chelators, lipophilic antioxidants and inhibitors of lipid peroxidation, and correlates with the accumulation of markers of lipid peroxidation, thus fulfilling the definition of ferroptosis, a recently described cell death process. The capacity of AML cells to detoxify lipid peroxides by increasing their cystine uptake to maintain major antioxidant molecule glutathione biosynthesis after exposure to APR-246 may be a key determinant of sensitivity to this compound. The association of APR-246 with induction of ferroptosis (either by pharmacological compounds, or genetic inactivation of SLC7A11 or GPX4) had a synergistic effect on the promotion of cell death, both in vivo and ex vivo.
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http://dx.doi.org/10.3324/haematol.2020.259531DOI Listing
January 2021

Multicenter Next-Generation Sequencing Studies between Theory and Practice: Harmonization of Data Analysis Using Real-World Myelodysplastic Syndrome Data.

J Mol Diagn 2021 Mar 23;23(3):347-357. Epub 2020 Dec 23.

Institute of Medical Informatics, University of Münster, Münster, Germany.

In the age of personalized medicine, genetic testing by means of targeted sequencing has taken a key role. However, when comparing different sets of targeted sequencing data, these are often characterized by a considerable lack of harmonization. Laboratories follow their own best practices, analyzing their own target regions. The question on how to best integrate data from different sites remains unanswered. Studying the example of myelodysplastic syndrome (MDS), we analyzed 11 targeted sequencing sets, collected from six different centers (n = 831). An intersecting target region of 43,076 bp (30 genes) was identified; whereas, the original target regions covered up to 499,097 bp (117 genes). Considering a region of interest in the context of MDS, a target region of 55,969 bp (31 genes) was identified. For each gene, coverage and sequencing data quality was evaluated, calculating a sequencing score. Analyses revealed huge differences between different data sets as well as between different genes. Analysis of the relation between sequencing score and mutation frequency in MDS revealed that most genes with high frequency in MDS could be sequenced without expecting low coverage or quality. Still, no gene appeared consistently unproblematic for all data sets. To allow for comparable results in a multicenter setting analyzing MDS, we propose to use a predefined target region of interest and to perform centralized data analysis using harmonized criteria.
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http://dx.doi.org/10.1016/j.jmoldx.2020.12.001DOI Listing
March 2021

Antileukemic activity of the VPS34-IN1 inhibitor in acute myeloid leukemia.

Oncogenesis 2020 Oct 22;9(10):94. Epub 2020 Oct 22.

Institut Cochin, Université de Paris, CNRS UMR8104, INSERM U1016, Paris, France.

Acute myeloid leukemia (AML) is an aggressive disease with a poor prognosis. Vacuolar protein sorting 34 (VPS34) is a member of the phosphatidylinositol-3-kinase lipid kinase family that controls the canonical autophagy pathway and vesicular trafficking. Using a recently developed specific inhibitor (VPS34-IN1), we found that VPS34 inhibition induces apoptosis in AML cells but not in normal CD34+ hematopoietic cells. Complete and acute inhibition of VPS34 was required for the antileukemic activity of VPS34-IN1. This inhibitor also has pleiotropic effects against various cellular functions related to class III PI3K in AML cells that may explain their survival impairment. VPS34-IN1 inhibits basal and L-asparaginase-induced autophagy in AML cells. A synergistic cell death activity of this drug was also demonstrated. VPS34-IN1 was additionally found to impair vesicular trafficking and mTORC1 signaling. From an unbiased approach based on phosphoproteomic analysis, we identified that VPS34-IN1 specifically inhibits STAT5 phosphorylation downstream of FLT3-ITD signaling in AML. The identification of the mechanisms controlling FLT3-ITD signaling by VPS34 represents an important insight into the oncogenesis of AML and could lead to new therapeutic strategies.
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http://dx.doi.org/10.1038/s41389-020-00278-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7581748PMC
October 2020

Elevated Calprotectin and Abnormal Myeloid Cell Subsets Discriminate Severe from Mild COVID-19.

Cell 2020 09 5;182(6):1401-1418.e18. Epub 2020 Aug 5.

INSERM U1287, Gustave Roussy Cancer Campus, Villejuif 94800, France; Département d'Hématologie, Gustave Roussy Cancer Campus, Villejuif 94800, France.

Blood myeloid cells are known to be dysregulated in coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2. It is unknown whether the innate myeloid response differs with disease severity and whether markers of innate immunity discriminate high-risk patients. Thus, we performed high-dimensional flow cytometry and single-cell RNA sequencing of COVID-19 patient peripheral blood cells and detected disappearance of non-classical CD14CD16 monocytes, accumulation of HLA-DR classical monocytes (Human Leukocyte Antigen - DR isotype), and release of massive amounts of calprotectin (S100A8/S100A9) in severe cases. Immature CD10CD101CXCR4 neutrophils with an immunosuppressive profile accumulated in the blood and lungs, suggesting emergency myelopoiesis. Finally, we show that calprotectin plasma level and a routine flow cytometry assay detecting decreased frequencies of non-classical monocytes could discriminate patients who develop a severe form of COVID-19, suggesting a predictive value that deserves prospective evaluation.
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http://dx.doi.org/10.1016/j.cell.2020.08.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7405878PMC
September 2020

Implications of TP53 allelic state for genome stability, clinical presentation and outcomes in myelodysplastic syndromes.

Nat Med 2020 10 3;26(10):1549-1556. Epub 2020 Aug 3.

Department of Hematology, Democritus University of Thrace Medical School, Alexandroupolis, Greece.

Tumor protein p53 (TP53) is the most frequently mutated gene in cancer. In patients with myelodysplastic syndromes (MDS), TP53 mutations are associated with high-risk disease, rapid transformation to acute myeloid leukemia (AML), resistance to conventional therapies and dismal outcomes. Consistent with the tumor-suppressive role of TP53, patients harbor both mono- and biallelic mutations. However, the biological and clinical implications of TP53 allelic state have not been fully investigated in MDS or any other cancer type. We analyzed 3,324 patients with MDS for TP53 mutations and allelic imbalances and delineated two subsets of patients with distinct phenotypes and outcomes. One-third of TP53-mutated patients had monoallelic mutations whereas two-thirds had multiple hits (multi-hit) consistent with biallelic targeting. Established associations with complex karyotype, few co-occurring mutations, high-risk presentation and poor outcomes were specific to multi-hit patients only. TP53 multi-hit state predicted risk of death and leukemic transformation independently of the Revised International Prognostic Scoring System (IPSS-R). Surprisingly, monoallelic patients did not differ from TP53 wild-type patients in outcomes and response to therapy. This study shows that consideration of TP53 allelic state is critical for diagnostic and prognostic precision in MDS as well as in future correlative studies of treatment response.
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http://dx.doi.org/10.1038/s41591-020-1008-zDOI Listing
October 2020

Pairing MCL-1 inhibition with venetoclax improves therapeutic efficiency of BH3-mimetics in AML.

Eur J Haematol 2020 Nov 4;105(5):588-596. Epub 2020 Aug 4.

Institut Cochin, CNRS UMR8104, INSERM U1016, Université de Paris, Paris, France.

Objectives: Venetoclax combined with hypomethylating agents is a new therapeutic strategy frequently used for treating AML patients who are not eligible for conventional chemotherapy. However, high response rates are heterogeneous due to different mechanisms mediating resistance to venetoclax such as up-regulation of MCL-1 expression. We thus tested the anti-leukemic activity of S63845, a specific MCL-1 inhibitor.

Methods: Apoptosis induces by S63845 with or without venetoclax was evaluated in primary AML samples and in AML cell lines co-cultured or not with bone marrow (BM) mesenchymal stromal cells. Sensitivity of leukemic cells to S63845 was correlated to the expression level of BCL-2, MCL-1, and BCL-XL determined by Western Blot and mass spectrometry-based proteomics.

Results: We observed that even if MCL-1 expression is weak compared to BCL-2, S63845 induces apoptosis of AML cells and strongly synergizes with venetoclax. Furthermore, AML cells resistant to venetoclax are highly sensitive to S63845. Interestingly, the synergistic effect of S63845 toward venetoclax-mediated apoptosis of AML cells is still observed in a context of interaction with the BM microenvironment that intrinsically mediates resistance to BCL2 inhibition.

Conclusion: These results are therefore of great relevance for clinicians as they provide the rational for combining BCL-2 and MCL-1 inhibition in AML.
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http://dx.doi.org/10.1111/ejh.13492DOI Listing
November 2020

Battle of the clones: paroxysmal nocturnal hemoglobinuria vs myelodysplastic syndrome.

Ann Hematol 2020 Oct 13;99(10):2459-2461. Epub 2020 Jun 13.

Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires de Paris, Hematology Laboratory, Georges Pompidou European Hospital, INSERM UMR-S1140, Paris, France.

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http://dx.doi.org/10.1007/s00277-020-04134-yDOI Listing
October 2020

Bone marrow oxidative stress and specific antioxidant signatures in myelodysplastic syndromes.

Blood Adv 2019 12;3(24):4271-4279

Centre National de la Recherche Scientifique (CNRS) Equipe de Recherche Labellisée 7001, LNOX "Leukemic Niche and Redox Metabolism," Tours, France.

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal stem cell disorders with an inherent tendency for transformation in secondary acute myeloid leukemia. This study focused on the redox metabolism of bone marrow (BM) cells from 97 patients compared with 25 healthy controls. The level of reactive oxygen species (ROS) was quantified by flow cytometry in BM cell subsets as well as the expression level of 28 transcripts encoding for major enzymes involved in the antioxidant cellular response. Our results highlight increased ROS levels in BM nonlymphoid cells and especially in primitive CD34posCD38low progenitor cells. Moreover, we identified a specific antioxidant signature, dubbed "antioxidogram," for the different MDS subgroups or secondary acute myeloblastic leukemia (sAML). Our results suggest that progression from MDS toward sAML could be characterized by 3 successive molecular steps: (1) overexpression of enzymes reducing proteic disulfide bonds (MDS with <5% BM blasts [GLRX family]); (2) increased expression of enzymes detoxifying H2O2 (MDS with 5% to 19% BM blasts [PRDX and GPX families]); and finally (3) decreased expression of these enzymes in sAML. The antioxidant score (AO-Score) defined by logistic regression from the expression levels of transcripts made it possible to stage disease progression and, interestingly, this AO-Score was independent of the revised International Scoring System. Altogether, this study demonstrates that MDS and sAML present an important disturbance of redox metabolism, especially in BM stem and progenitor cells and that the specific molecular antioxidant response parameters (antioxidogram, AO-Score) could be considered as useful biomarkers for disease diagnosis and follow-up.
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http://dx.doi.org/10.1182/bloodadvances.2019000677DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6929385PMC
December 2019

[Accreditation strategy for rare somatic molecular abnormalities detected or quantified by polymerase chain reaction: GBMHM recommendations].

Ann Biol Clin (Paris) 2019 12;77(6):681-684

Laboratoire d'hématologie, Hôpital Nord, Centre hospitalier universitaire de Saint-Étienne, Saint-Étienne, France.

In 2020, accreditation of molecular tests according to ISO 15189 is a requirement for all French medical laboratories. For many years, the GBMHM group (French Group of Molecular Biologists in Hematology) supports this approach through organization of external quality evaluation campaigns, and by publishing recommendations that have allowed the accreditation of the most frequent molecular tests for most laboratories. However, some molecular abnormalities concerns very few patients (and sometimes a single patient), and therefore cannot be evaluated in the same way, because of the lack of external quality controls or inter-laboratory comparisons. In order to allow the accreditation of these rare analyzes, the GBMHM proposes recommendations, based on the fact that analyzes using the same methodology than those already accredited by an extensive validation process, may be accredited without the need for full analytical validation. In particular, assays based on quantitative PCR or endpoint PCR may be accredited after verification of primer specificity, repeatability and/or reproducibility, and the determination of detection or linearity limits. These recommendations, by defining the validation approach for rare molecular abnormalities, make it possible to extend the requirement of accreditation for rare tests, to provide the best patient care.
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http://dx.doi.org/10.1684/abc.2019.1498DOI Listing
December 2019

Mastocytosis onset in a patient with treated hairy cell leukemia: Just a coincidence?

Blood Cells Mol Dis 2020 03 29;81:102392. Epub 2019 Nov 29.

Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris Centre, Service d'Hématologie Clinique, Paris, France; Université Paris Descartes, Faculté de Médecine Sorbonne Paris Cité, Paris, France.

Mastocytosis is a mast cell disease caused by functionally defective infiltrating mast cells and CD34+ mast cell precursors. The heterogeneous group of mast cell disorders is categorized into five variants in the updated 2017 World Health Organization (WHO) classification among those systemic mastocytosis with an associated neoplasm (SM-AHN). Except for myeloid neoplasia, lymphoproliferative disorders associated to SM-AHN are more scarce. Here, we report the second case ever described of associated mastocytosis and hairy-cell disease. A 38-year-old female patient without any specific medical history was diagnosed a hairy cell leukemia and BRAF mutation was found in hairy cells. Since purine-analogs were avoided to prevent prolonged myelosuppression, she was treated with vemurafenib and rituximab. Despite early discontinuation due to vemurafenib-induced agranulocytosis, a partial response was observed. Strikingly, bone marrow biopsy performed one month after vemurafenib discontinuation revealed a nodular infiltration by 30% tumoral mastocytes. Along with elevated tryptase level, KIT mutation on mastocytes and clinical exam, the patient was diagnosed with systemic mastocytosis with an associated hematological neoplasm (SM-AHN). No BRAF mutation was found on mastocytes. The physiopathology of this association is not known and might be only a coincidence or a common genetic driver mutation enhancing mast and hairy cells.
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http://dx.doi.org/10.1016/j.bcmd.2019.102392DOI Listing
March 2020

Phenotypic landscape of granulocytes and monocytes by multiparametric flow cytometry: A prospective study of a 1-tube panel strategy for diagnosis and prognosis of patients with MDS.

Cytometry B Clin Cytom 2020 05 9;98(3):226-237. Epub 2019 Sep 9.

Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris Centre, Service d'Hématologie Biologique, Paris, France.

Background: Multiparametric flow cytometry (MFC) was recently reported to be a helpful additional tool in the diagnosis of myelodysplastic syndromes (MDS). However, numerous aberrancies have been reported that makes their evaluation difficult as part of a routine diagnosis.

Methods: Here, we validated a 1-tube panel for the evaluation of granulocytic and monocytic maturation by MFC and correlated our findings with diagnosis and prognosis of MDS. A total of 251 samples with MDS suspicion were prospectively analyzed and compared to an internal reference database leading to the calculation of the Diff score.

Results: The associated specificity and sensitivity values of this scoring system were 92.1% and 60.4% in a first learning cohort and 96.7% and 65.2% in a second independent validation cohort. The combination of the Diff score with the concomitantly calculated Ogata score increased the sensitivity to 74.2% and 78.3% in the learning and validation cohorts, respectively. Finally, a normal Diff score in MDS patients was associated with a significant prolonged progression-free survival.

Conclusions: Taken together, the present data indicate that our strategy is a sensitive and specific MFC tool for the diagnosis of MDS-related cytopenia(s) which could be also useful for predicting evolution of these diseases.
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http://dx.doi.org/10.1002/cyto.b.21843DOI Listing
May 2020

Paraneoplastic Hyperleukocytosis Mimicking Hematologic Malignancy Revealing a Localized Lung Cancer.

Ann Thorac Surg 2020 03 10;109(3):e203-e206. Epub 2019 Aug 10.

Université Paris Descartes, Faculté de Médecine, Sorbonne Paris Cité, Paris, France; Service d'Hématologie, Hôpital Cochin, Assistance Publique - Hôpitaux de Paris, Paris, France; INSERM U1016, Institut Cochin, Paris, France.

Paraneoplastic leukemoid reaction is a challenging differential diagnosis when it presents at the time of diagnosis of cancer. Severe hyperleukocytosis with elevation of blood neutrophils and monocytes counts can evoke myeloid hematologic malignancies. We report the case of a patient who presented with blood and bone marrow features highly suggestive of chronic myelomonocytic leukemia. The diagnosis of primary lung sarcomatoid carcinoma was performed. Surgical removal of this tumor which will always remain the priority led to full normalization of blood cell count.
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http://dx.doi.org/10.1016/j.athoracsur.2019.06.064DOI Listing
March 2020

A variant erythroferrone disrupts iron homeostasis in -mutated myelodysplastic syndrome.

Sci Transl Med 2019 07;11(500)

Université de Paris, Paris 75006, France.

Myelodysplastic syndromes (MDS) with ring sideroblasts are hematopoietic stem cell disorders with erythroid dysplasia and mutations in the splicing factor gene. Patients with MDS with mutations often accumulate excessive tissue iron, even in the absence of transfusions, but the mechanisms that are responsible for their parenchymal iron overload are unknown. Body iron content, tissue distribution, and the supply of iron for erythropoiesis are controlled by the hormone hepcidin, which is regulated by erythroblasts through secretion of the erythroid hormone erythroferrone (ERFE). Here, we identified an alternative transcript in patients with MDS with the mutation. Induction of this transcript in primary -mutated bone marrow erythroblasts generated a variant protein that maintained the capacity to suppress hepcidin transcription. Plasma concentrations of ERFE were higher in patients with MDS with an gene mutation than in patients with wild-type MDS. Thus, hepcidin suppression by a variant ERFE is likely responsible for the increased iron loading in patients with -mutated MDS, suggesting that ERFE could be targeted to prevent iron-mediated toxicity. The expression of the variant transcript that was restricted to -mutated erythroblasts decreased in lenalidomide-responsive anemic patients, identifying variant ERFE as a specific biomarker of clonal erythropoiesis.
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http://dx.doi.org/10.1126/scitranslmed.aav5467DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8005358PMC
July 2019

Impact of genotype in relapsed and refractory acute myeloid leukaemia patients treated with clofarabine and cytarabine: a retrospective study.

Br J Haematol 2019 10 18;187(1):65-72. Epub 2019 Jun 18.

Faculté de Médecine Sorbonne Paris Cité, Université Paris Descartes, Paris, France.

The treatment of relapsed/refractory (R/R) acute myeloid leukaemia (AML) remains a challenge. Among salvage chemotherapy regimens, the clofarabine and cytarabine (CLARA) combination has been widely evaluated and has a favourable safety/efficacy balance. Predictive factors of efficacy in patients with R/R AML are unclear, particularly the impact of AML-related gene mutations. We report our single-centre experience on 34 R/R AML patients treated with CLARA, with a focus on the genetic characterization of our cohort. CLARA yielded a 47% response rate among this poor-prognosis AML population, while two patients (5·8%) died due to treatment-related toxicity. The two-year progression-free survival and overall survival rates were 29·4% and 35·3%, respectively. Nine patients (26%) had long-term response with a median follow-up of 39·5 months among the responders, of whom six underwent haematopoietic stem cell transplantation. Adverse karyotype did not correlate with response or survival, and secondary AML were more frequent among responders to CLARA, suggesting that this combination may successfully salvage R/R AML patients regardless of adverse prognostic markers. We also observed that a low mutational burden and absence of splice mutations correlated with prolonged survival after CLARA, suggesting that extensive genotyping may have prognostic implications in R/R AML.
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http://dx.doi.org/10.1111/bjh.16045DOI Listing
October 2019

The fraction of CD117/c-KIT-expressing erythroid precursors predicts ESA response in low-risk myelodysplastic syndromes.

Cytometry B Clin Cytom 2019 05 9;96(3):215-222. Epub 2019 Apr 9.

Service d'Hématologie-Immunologie-Transfusion, Hôpitaux Universitaires Paris Ile de France Ouest, Boulogne 92100, France.

Background: Compelling evidence has emerged for the relevance of flow cytometry (FC) in the diagnostic work-up of myelodysplastic syndromes (MDS) but due to technical issues, the erythroid lineage has been under investigated, specifically in the therapeutic context.

Methods: Using the "no red cell lysis" method developed to set up the RED-score, we specifically quantified the fraction of CD117/c-KIT-expressing erythroid precursors in a cohort of 144 MDS patients and studied the correlation with response to erythropoiesis-stimulating agents (ESA) in a sub cohort of 63 low-risk MDS patients.

Results: We confirmed the previously reported increase in CD117/c-KIT-expressing erythroid precursors in a subset of MDS patients and demonstrated a strong association between a cut off of CD117/c-KIT-expressing erythroid precursors ≥3% and ESA response (P = 0.001), independent of red blood cell requirement. From our observations, we hypothesized that a decrease in CD117/c-KIT-expressing erythroid precursors could be a mechanism of ESA failure. Moreover, the fraction of CD117/c-KIT-expressing erythroid precursors was correlated with progression-free survival in low-risk MDS patients (P = 0.018). In vitro, we demonstrated in an EPO dependent cell line that CD117/c-KIT expression is necessary for cell survival under EPO stimulation.

Conclusions: The quantification of the CD117/c-KIT-expressing erythroid precursors could be proposed as a new theranostic and prognostic marker in MDS treated by ESA. Future studies will be required to determine whether modulating CD117/c-KIT expression and signaling could be used to improve anemia in MDS. © 2019 International Clinical Cytometry Society.
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http://dx.doi.org/10.1002/cyto.b.21781DOI Listing
May 2019

Hematopoietic niche drives FLT3-ITD acute myeloid leukemia resistance to quizartinib STAT5-and hypoxia-dependent upregulation of AXL.

Haematologica 2019 10 28;104(10):2017-2027. Epub 2019 Mar 28.

Université de Bordeaux, Institut National de la Santé et de la Recherche Médicale INSERM U1035, F-33000 Bordeaux

Internal tandem duplication in Fms-like tyrosine kinase 3 (FLT3-ITD) is the most frequent mutation observed in acute myeloid leukemia (AML) and correlates with poor prognosis. FLT3 tyrosine kinase inhibitors are promising for targeted therapy. Here, we investigated mechanisms dampening the response to the FLT3 inhibitor quizartinib, which is specific to the hematopoietic niche. Using AML primary samples and cell lines, we demonstrate that convergent signals from the hematopoietic microenvironment drive FLT3-ITD cell resistance to quizartinib through the expression and activation of the tyrosine kinase receptor AXL. Indeed, cytokines sustained phosphorylation of the transcription factor STAT5 in quizartinib-treated cells, which enhanced AXL expression by direct binding of a conserved motif in its genomic sequence. Likewise, hypoxia, another well-known hematopoietic niche hallmark, also enhanced AXL expression. Finally, in a xenograft mouse model, inhibition of AXL significantly increased the response of FLT3-ITD cells to quizartinib exclusively within a bone marrow environment. These data highlight a new bypass mechanism specific to the hematopoietic niche that hampers the response to quizartinib through combined upregulation of AXL activity. Targeting this signaling offers the prospect of a new therapy to eradicate resistant FLT3-ITD leukemic cells hidden within their specific microenvironment, thereby preventing relapses from FLT3-ITD clones.
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http://dx.doi.org/10.3324/haematol.2018.205385DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6886433PMC
October 2019

Biology and prognostic impact of clonal plasmacytoid dendritic cells in chronic myelomonocytic leukemia.

Leukemia 2019 10 20;33(10):2466-2480. Epub 2019 Mar 20.

INSERM U1170, Gustave Roussy Cancer Center, Villejuif, France.

Islands of CD123 cells have been commonly described in the bone marrow of patients with chronic myelomonocytic leukemia (CMML). Using a multiparameter flow cytometry assay, we detected an excess of CD123 mononucleated cells that are lineage-negative, CD45, CD11c, CD33, HLA-DR, BDCA-2, BDCA-4 in the bone marrow of 32/159 (20%) patients. Conventional and electron microscopy, flow cytometry detection of cell surface markers, gene expression analyses, and the ability to synthesize interferon alpha in response to Toll-like receptor agonists identified these cells as bona fide plasmacytoid dendritic cells (pDCs). Whole-exome sequencing of sorted monocytes and pDCs identified somatic mutations in genes of the oncogenic RAS pathway in the two cell types of every patient. CD34 cells could generate high amount of pDCs in the absence of FMS-like tyrosine kinase 3-ligand (FLT3L). Finally, an excess of pDCs correlates with regulatory T cell accumulation and an increased risk of acute leukemia transformation. These results demonstrate the FLT3L-independent accumulation of clonal pDCs in the bone marrow of CMML patients with mutations affecting the RAS pathway, which is associated with a higher risk of disease progression.
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http://dx.doi.org/10.1038/s41375-019-0447-3DOI Listing
October 2019

Enhanced Renewal of Erythroid Progenitors in Myelodysplastic Anemia by Peripheral Serotonin.

Cell Rep 2019 03;26(12):3246-3256.e4

Institut Imagine, INSERM U1163, CNRS ERL 8254, Université Paris Descartes, Sorbonne Paris-Cité, Laboratoire d'Excellence GR-Ex, Paris, France. Electronic address:

Tryptophan as the precursor of several active compounds, including kynurenine and serotonin, is critical for numerous important metabolic functions. Enhanced tryptophan metabolism toward the kynurenine pathway has been associated with myelodysplastic syndromes (MDSs), which are preleukemic clonal diseases characterized by dysplastic bone marrow and cytopenias. Here, we reveal a fundamental role for tryptophan metabolized along the serotonin pathway in normal erythropoiesis and in the physiopathology of MDS-related anemia. We identify, both in human and murine erythroid progenitors, a functional cell-autonomous serotonergic network with pro-survival and proliferative functions. In vivo studies demonstrate that pharmacological increase of serotonin levels using fluoxetine, a common antidepressant, has the potential to become an important therapeutic strategy in low-risk MDS anemia refractory to erythropoietin.
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http://dx.doi.org/10.1016/j.celrep.2019.02.071DOI Listing
March 2019

EZH1/2 function mostly within canonical PRC2 and exhibit proliferation-dependent redundancy that shapes mutational signatures in cancer.

Proc Natl Acad Sci U S A 2019 03 13;116(13):6075-6080. Epub 2019 Mar 13.

Institut Curie, Paris Sciences et Lettres Research University, 75005 Paris, France;

Genetic mutations affecting chromatin modifiers are widespread in cancers. In malignant peripheral nerve sheath tumors (MPNSTs), Polycomb repressive complex 2 (PRC2), which plays a crucial role in gene silencing, is inactivated through recurrent mutations in core subunits embryonic ectoderm development (EED) and suppressor of zeste 12 homolog (SUZ12), but mutations in PRC2's main catalytic subunit enhancer of zeste homolog 2 (EZH2) have never been found. This is in contrast to myeloid and lymphoid malignancies, which harbor frequent loss-of-function mutations in EZH2. Here, we investigated whether the absence of EZH2 mutations in MPNST is due to a PRC2-independent (i.e., noncanonical) function of the enzyme or to redundancy with EZH1. We show that, in the absence of SUZ12, EZH2 remains bound to EED but loses its interaction with all other core and accessory PRC2 subunits. Through genetic and pharmacological analyses, we unambiguously establish that EZH2 is functionally inert in this context, thereby excluding a PRC2-independent function. Instead, we show that EZH1 and EZH2 are functionally redundant in the slowly proliferating MPNST precursors. We provide evidence that the compensatory function of EZH1 is alleviated upon higher proliferation. This work reveals how context-dependent redundancies can shape tumor-type specific mutation patterns in chromatin regulators.
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http://dx.doi.org/10.1073/pnas.1814634116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6442582PMC
March 2019