Publications by authors named "Peter Valent"

537 Publications

A STAT5B-CD9 axis determines self-renewal in hematopoietic and leukemic stem cells.

Blood 2021 Jul 28. Epub 2021 Jul 28.

Veterinary University of Vienna, Vienna, Austria.

The transcription factors STAT5A and STAT5B are critical in hematopoiesis and leukemia. They are widely believed to have redundant functions but we describe a unique role for STAT5B in driving the self-renewal of hematopoietic and leukemic stem cells (HSCs/LSCs). We find STAT5B to be specifically activated in HSCs and LSCs, where it induces many genes associated with quiescence and self-renewal, including the surface marker CD9. Levels of CD9 represent a prognostic marker for patients with STAT5-driven leukemia and our findings suggest that anti-CD9 antibodies may be useful in their treatment to target and eliminate LSCs. We show that it is vital to consider STAT5A and STAT5B as distinct entities in normal and malignant hematopoiesis.
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http://dx.doi.org/10.1182/blood.2021010980DOI Listing
July 2021

TET2 and DNMT3A Mutations Exert Divergent Effects on DNA Repair and Sensitivity of Leukemia Cells to PARP Inhibitors.

Cancer Res 2021 Jul 2. Epub 2021 Jul 2.

Cambridge Stem Cell Institute/Haematology, University of Cambridge.

Somatic variants in TET2 and DNMT3A are founding mutations in hematological malignancies that affect the epigenetic regulation of DNA methylation. Mutations in both genes often co-occur with activating mutations in oncogenic tyrosine kinases such as FLT3ITD, BCR-ABL1, JAK2V617F, and MPLW515L, or with mutations affecting related signaling pathways such as NRASG12D and CALRdel52. Here we show that TET2 and DNMT3A mutations exert divergent roles in regulating DNA repair activities in leukemia cells expressing these oncogenes. Malignant TET2-deficient cells displayed downregulation of BRCA1 and LIG4, resulting in reduced activity of BRCA1/2-mediated homologous recombination (HR) and DNA-PK -mediated non-homologous end-joining (D-NHEJ), respectively. TET2-deficient cells relied on PARP1-mediated alternative NHEJ (Alt-NHEJ) for protection from the toxic effects of spontaneous and drug-induced DNA double-strand breaks. Conversely, DNMT3A-deficient cells favored HR/D-NHEJ owing to downregulation of PARP1 and reduction of Alt-NHEJ. Consequently, malignant TET2-deficient cells were sensitive to PARP inhibitor (PARPi) treatment in vitro and in vivo, whereas DNMT3A-deficient cells were resistant. Disruption of TET2 dioxygenase activity or TET2 - Wilms tumor 1 (WT1) binding ability were responsible for DNA repair defects and sensitivity to PARPi associated with TET2 deficiency. Moreover, mutation or deletion of WT1 mimicked the effect of TET2 mutation on DSB repair activity and sensitivity to PARPi. Collectively, these findings reveal that TET2 and WT1 mutations may serve as biomarkers of synthetic lethality triggered by PARPi, which should be explored therapeutically.
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http://dx.doi.org/10.1158/0008-5472.CAN-20-3761DOI Listing
July 2021

Selecting the Right Criteria and Proper Classification to Diagnose Mast Cell Activation Syndromes: A Critical Review.

J Allergy Clin Immunol Pract 2021 Jun 22. Epub 2021 Jun 22.

Department of Internal Medicine, Division of Rheumatology, Allergy, and Immunology, Virginia Commonwealth University, Richmond, Va.

In recent years, knowledge about mechanisms underlying mast cell activation (MCA) and accumulation in various pathologic conditions increased substantially. In addition, criteria and a classification of MCA syndromes (MCASs) have been set forth. MCAS is defined by typical clinical symptoms, a substantial increase in serum tryptase level during an attack over the patient's baseline tryptase, and a response of the symptoms to drugs targeting mast cells, mediator production, and/or mediator effects. Alternative diagnostic criteria of MCAS have also been suggested, but these alternative criteria often lack specificity and validation. In this report, we critically review the contemporary literature relating to MCAS and compare the specificity, sensitivity, and strength of MCAS-related parameters within proposals to diagnose and classify MCAS and its variants. Furthermore, we highlight the need to apply specific consensus criteria in the evaluation and classification of MCAS in individual patients. This is an urgent and important medical necessity because as an increasing number of patients are being given a misdiagnosis of MCAS based on nonspecific criteria, which contributes to confusion and frustration by patients and caregivers and sometimes may delay recognition and treatment of correct medical conditions that often turn out to be unrelated to MCA.
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http://dx.doi.org/10.1016/j.jaip.2021.06.011DOI Listing
June 2021

Case report of a clinically indolent but morphologically high-grade cutaneous mast cell tumor in an adult: Atypical cutaneous mastocytoma or mast cell sarcoma?

J Cutan Pathol 2021 Jun 21. Epub 2021 Jun 21.

Department of Pathology and Medical Biology, University Medical Centre Groningen, Groningen, The Netherlands.

We present a case of an adult male with a solitary mast cell tumor of the skin with unusual nuclear pleomorphism and mitotic activity. The tumor was excised, recurred within 2 years, was reexcised after 4 years and did not recur >6 years after diagnosis. The tumor showed progressive cytonuclear atypia and a high mitotic and proliferation rate by Ki67-staining from the onset. No KIT mutations were identified in the tumor and bone marrow. Serum tryptase levels and a bone marrow aspirate and trephine biopsy were normal. Although the histomorphology of the skin tumor was consistent with mast cell sarcoma, the clinical behavior without systemic progression argued against this diagnosis. The tumor was finally considered as atypical mastocytoma, borderline to mast cell sarcoma. Currently, the patient is in close follow-up and still in complete remission.
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http://dx.doi.org/10.1111/cup.14088DOI Listing
June 2021

Mastocytosis, MCAS, and Related Disorders-Diagnosis, Classification, and Therapy.

Int J Mol Sci 2021 May 10;22(9). Epub 2021 May 10.

Department of Dermatology, Venerology and Allergology Medical University of Gdansk, 80-211 Gdańsk, Poland.

Mastocytosis is a heterogeneous group of hematologic neoplasms defined by an accumulation of neoplastic mast cells (MC) in the skin, bone marrow, and other visceral organs [...].
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http://dx.doi.org/10.3390/ijms22095024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8125991PMC
May 2021

Clinical and histopathological features of myeloid neoplasms with concurrent Janus kinase 2 (JAK2) V617F and KIT proto-oncogene, receptor tyrosine kinase (KIT) D816V mutations.

Br J Haematol 2021 Jul 1;194(2):344-354. Epub 2021 Jun 1.

Haematology and Oncology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.

We report on 45 patients with myeloid neoplasms and concurrent Janus kinase 2 (JAK2) V617F and KIT proto-oncogene, receptor tyrosine kinase (KIT) D816V (JAK2 /KIT ) mutations, which are individually identified in >60% of patients with classical myeloproliferative neoplasms (MPN) and >90% of patients with systemic mastocytosis (SM) respectively. In SM, the concurrent presence of a clonal non-mast cell neoplasm [SM with associated haematological neoplasm (SM-AHN)] usually constitutes a distinct subtype associated with poor survival. All 45 patients presented with a heterogeneous combination of clinical/morphological features typical of the individual disorders (e.g. leuco-/erythro-/thrombocytosis and elevated lactate dehydrogenase for MPN; elevated serum tryptase and alkaline phosphatase for SM). Overlapping features identified in 70% of patients included splenomegaly, cytopenia(s), bone marrow fibrosis and additional somatic mutations. Molecular dissection revealed discordant development of variant allele frequency for both mutations and absence of concurrently positive single-cell derived colonies, indicating disease evolution in two independent clones rather than monoclonal disease in >60% of patients examined. Overall survival of JAK2 /KIT patients without additional somatic high-risk mutations [HRM, e.g. in serine and arginine-rich splicing factor 2 (SRSF2), additional sex combs like-1 (ASXL1) or Runt-related transcription factor 1 (RUNX1)] at 5 years was 77%, indicating that the mutual impact of JAK2 V617F and KIT D816V on prognosis is fundamentally different from the adverse impact of additional HRM in the individual disorders.
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http://dx.doi.org/10.1111/bjh.17567DOI Listing
July 2021

Eosinophils and eosinophil-associated disorders: immunological, clinical, and molecular complexity.

Semin Immunopathol 2021 Jun 30;43(3):423-438. Epub 2021 May 30.

Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.

Eosinophils and their mediators play a crucial role in various reactive states such as bacterial and viral infections, chronic inflammatory disorders, and certain hematologic malignancies. Depending on the underlying pathology, molecular defect(s), and the cytokine- and mediator-cascades involved, peripheral blood and tissue hypereosinophilia (HE) may develop and may lead to organ dysfunction or even organ damage which usually leads to the diagnosis of a HE syndrome (HES). In some of these patients, the etiology and impact of HE remain unclear. These patients are diagnosed with idiopathic HE. In other patients, HES is diagnosed but the etiology remains unknown - these patients are classified as idiopathic HES. For patients with HES, early therapeutic application of agents reducing eosinophil counts is usually effective in avoiding irreversible organ damage. Therefore, it is important to systematically explore various diagnostic markers and to correctly identify the disease elicitors and etiology. Depending on the presence and type of underlying disease, HES are classified into primary (clonal) HES, reactive HES, and idiopathic HES. In most of these patients, effective therapies can be administered. The current article provides an overview of the pathogenesis of eosinophil-associated disorders, with special emphasis on the molecular, immunological, and clinical complexity of HE and HES. In addition, diagnostic criteria and the classification of eosinophil disorders are reviewed in light of new developments in the field.
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http://dx.doi.org/10.1007/s00281-021-00863-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8164832PMC
June 2021

Core binding factor leukemia hijacks T-cell prone PU.1 antisense promoter.

Blood 2021 May 19. Epub 2021 May 19.

University of Alabama at Birmingham, Birmingham, Alabama, United States.

The blood system serves as a key model for cell differentiation and cancer. It is orchestrated by precise spatiotemporal expression of crucial transcription factors. One of the key master regulators in the hematopoietic systems is PU.1. Reduced levels of PU.1 are characteristic for human acute myeloid leukemia (AML) and are known to induce AML in mouse models. Here, we demonstrate that transcriptional downregulation of PU.1 is an active process involving an alternative promoter in intron 3 that is induced by RUNX transcription factors driving non-coding antisense transcription. Core binding factor (CBF) fusions, RUNX1-ETO and CBFβ-MYH11 in t(8;21) and inv(16) AML, respectively, activate the PU.1 antisense promoter that results in a shift from sense towards antisense transcription and myeloid differentiation blockade. In patients with CBF-AML, we found that an elevated antisense/sense transcript and promoter accessibility ratio represents a hallmark compared to normal karyotype AML or healthy CD34+ cells. Competitive interaction of an enhancer with the proximal or the antisense promoter forms a binary on/off switch for either myeloid or T-cell development. Leukemic CBF fusions thus utilize a physiologic mechanism employed by T-cells to decrease sense transcription. Our study is the first example of a sense/antisense promoter competition as a crucial functional switch for gene expression perturbation by oncogenes. Hence, this disease mechanism reveals a previously unknown Achilles heel for future precise therapeutic targeting of oncogene-induced chromatin remodeling.
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http://dx.doi.org/10.1182/blood.2020008971DOI Listing
May 2021

RAS mutations drive proliferative chronic myelomonocytic leukemia via a KMT2A-PLK1 axis.

Nat Commun 2021 05 18;12(1):2901. Epub 2021 May 18.

Sigmund Freud University Vienna, Vienna, Austria.

Proliferative chronic myelomonocytic leukemia (pCMML), an aggressive CMML subtype, is associated with dismal outcomes. RAS pathway mutations, mainly NRAS, define the pCMML phenotype as demonstrated by our exome sequencing, progenitor colony assays and a Vav-Cre-Nras mouse model. Further, these mutations promote CMML transformation to acute myeloid leukemia. Using a multiomics platform and biochemical and molecular studies we show that in pCMML RAS pathway mutations are associated with a unique gene expression profile enriched in mitotic kinases such as polo-like kinase 1 (PLK1). PLK1 transcript levels are shown to be regulated by an unmutated lysine methyl-transferase (KMT2A) resulting in increased promoter monomethylation of lysine 4 of histone 3. Pharmacologic inhibition of PLK1 in RAS mutant patient-derived xenografts, demonstrates the utility of personalized biomarker-driven therapeutics in pCMML.
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http://dx.doi.org/10.1038/s41467-021-23186-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8131698PMC
May 2021

Secondary cytogenetic abnormalities in core-binding factor AML harboring inv(16) vs t(8;21).

Blood Adv 2021 05;5(10):2481-2489

Adult Bone Marrow Transplant Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY.

Patients with core-binding factor (CBF) acute myeloid leukemia (AML), caused by either t(8;21)(q22;q22) or inv(16)(p13q22)/t(16;16)(p13;q22), have higher complete remission rates and longer survival than patients with other subtypes of AML. However, ∼40% of patients relapse, and the literature suggests that patients with inv(16) fare differently from those with t(8;21). We retrospectively analyzed 537 patients with CBF-AML, focusing on additional cytogenetic aberrations to examine their impact on clinical outcomes. Trisomies of chromosomes 8, 21, or 22 were significantly more common in patients with inv(16)/t(16;16): 16% vs 7%, 6% vs 0%, and 17% vs 0%, respectively. In contrast, del(9q) and loss of a sex chromosome were more frequent in patients with t(8;21): 15% vs 0.4% for del(9q), 37% vs 0% for loss of X in females, and 44% vs 5% for loss of Y in males. Hyperdiploidy was more frequent in patients with inv(16) (25% vs 9%, whereas hypodiploidy was more frequent in patients with t(8;21) (37% vs 3%. In multivariable analyses (adjusted for age, white blood counts at diagnosis, and KIT mutation status), trisomy 8 was associated with improved overall survival (OS) in inv(16), whereas the presence of other chromosomal abnormalities (not trisomy 8) was associated with decreased OS. In patients with t(8;21), hypodiploidy was associated with improved disease-free survival; hyperdiploidy and del(9q) were associated with improved OS. KIT mutation (either positive or not tested, compared with negative) conferred poor prognoses in univariate analysis only in patients with t(8;21).
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http://dx.doi.org/10.1182/bloodadvances.2020003605DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8152510PMC
May 2021

Impact of age on the cumulative risk of transformation in patients with chronic myelomonocytic leukaemia.

Eur J Haematol 2021 Aug 1;107(2):265-274. Epub 2021 Jun 1.

Department of Internal Medicine V with Hematology, Oncology and Palliative Medicine, Hospital Hietzing, Vienna, Austria.

In older patients with chronic myelomonocytic leukaemia (CMML) and limited life expectancy due to age and or comorbidities, it is particularly important to consider the risk of transformation for individualised treatment decisions. There is limited information on potential differences between younger and older CMML patients regarding the cumulative risk of transformation as well as haematological, molecular and biologic characteristics. We analysed data from the Austrian Biodatabase for CMML (ABCMML) to compare these parameters in 518 CMML patients. Categorisation of patients into 3 age-related groups: <60 years, 60-79 years and ≥80 years, showed a significantly lower risk of transformation at higher age by competing risk analysis, with a 4-year risk of 39%, 23% and 13%, respectively (P < .0001). The lower probability of transformation was associated with a lower percentage of blast cells in the peripheral blood (PB) of older patients. Furthermore, we provide a simple score based on age, PB blasts and platelet counts that allowed us to define subgroups of CMML patients with a different cumulative transformation risk, including a low-risk group with a transformation risk of only 5%. Our findings may facilitate reasonable treatment decisions in elderly patients with CMML.
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http://dx.doi.org/10.1111/ejh.13647DOI Listing
August 2021

Culturing cells with mast cell phenotype and function: Comparison of peripheral blood and bone marrow as a source.

J Immunol Methods 2021 Aug 30;495:113061. Epub 2021 Apr 30.

University of Antwerp, Faculty of Medicine and Health Sciences, Department of Immunology, Allergology, Rheumatology and the Infla-Med Centre of Excellence, Antwerp (Belgium) and Immunology, Allergology, Rheumatology, Antwerp University Hospital, Antwerp, Belgium; Department of Immunology and Allergology, AZ Jan Palfijn Gent, Ghent, Belgium.

Background: Studies on the mechanisms that govern mast cell (MC) functions are hindered by the difficulties in isolating sufficient numbers of these tissue-resident cells. Therefore, many research groups use cultured human MCs obtained out of progenitor cells. However, these culture methods significantly differ regarding primary source material, culture durations and conditions. Consequently, the finally obtained cells are likely to exhibit morphological, phenotypical and/or functional heterogeneity.

Objective: To compare the phenotype and functionality of cells cultured from peripheral blood and bone marrow progenitor cells from patients with suspected clonal MC disease. These cells are designated as PBCMCs and BMCMCs, respectively.

Methods: Twenty paired PBCMCs and BMCMCs cultures starting from CD34 progenitor cells were compared. Cells were cultured for 4 weeks. Phenotyping included Giemsa and CD117 staining and flow cytometric staining for CD117, CD203c, FcεRI, MRGPRX2, CD300a, CD32, CD63 and CD25. Functional assessment included measurement of the up-regulation of CD63 after cross-linking of the high affinity receptor for IgE (FcεRI) with anti-FcεRI and ligation of MRGPRX2 with substance P.

Results: PBCMCs and BMCMCs are phenotypically comparable. Functionally, after activation with anti-FcεRI and substance P, PBCMCs and BMCMCs show similar up-regulation of the lysosomal degranulation marker CD63. However, the yield of PBCMCs is higher than BMCMs and peripheral blood cultures are purer than bone marrow cultures.

Conclusion: PBCMCs are an attractive alternative to the more difficult to obtain BMCMCs for the exploration of the complex mechanisms that govern IgE- and MRGPRX2-dependent MC activation and degranulation. Unlike BMCMCs, PBCMCs are easily accessible and enable repetitive analyses.
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http://dx.doi.org/10.1016/j.jim.2021.113061DOI Listing
August 2021

Metabolome and lipidome derangements during a severe mast cell activation event in a patient with indolent systemic mastocytosis.

J Allergy Clin Immunol 2021 Apr 20. Epub 2021 Apr 20.

Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.

Background: The number of mast cells in various organs is elevated manifold in individuals with systemic mastocytosis. Degranulation can lead to life-threatening symptomatology. No data about the alterations of the metabolome and lipidome during an attack have been published.

Objective: Our aim was to analyze changes in metabolomics and lipidomics during the acute phase of a severe mast cell activation event.

Methods: A total of 43 metabolites and 11 lipid classes comprising 200 subvariants from multiple plasma samples in duplicate, covering 72 hours of a severe mast cell activation attack with nausea and vomiting, were compared with 2 baseline samples by using quantitative liquid chromatography-mass spectrometry.

Results: A strong enterocyte dysfunction reflected in an almost 20-fold reduction in the functional small bowel length was extrapolated from strongly reduced ornithine and citrulline concentrations and was very likely secondary to severe endothelial cell dysfunction with hypoperfusion and extensive vascular leakage. Highly increased histamine and lactate concentrations accompanied the peak in clinical symptoms. Elevated asymmetric and symmetric dimethylarginine levels combined with reduced arginine levels compromised endothelial nitric oxide synthase activity and nitric oxide signaling. Specific and extensive depletion of many lysophosphatidylcholine variants indicates localized autotaxin activation and lysophosphatidic acid release. A strong correlation of clinical parameters with histamine concentrations and symptom reduction after 100-fold elevated plasma diamine oxidase concentrations implies that histamine is the key driver of the acute phase.

Conclusions: Rapid elimination of elevated histamine concentrations through use of recombinant human diamine oxidase, supplementation of lysophosphatidylcholine for immunomodulation, inhibition of autotaxin activity, and/or blockade of lysophosphatidic acid receptors might represent new treatment options for life-threatening mast cell activation events.
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http://dx.doi.org/10.1016/j.jaci.2021.03.043DOI Listing
April 2021

COVID-19 Vaccination in Mastocytosis: Recommendations of the European Competence Network on Mastocytosis (ECNM) and American Initiative in Mast Cell Diseases (AIM).

J Allergy Clin Immunol Pract 2021 06 5;9(6):2139-2144. Epub 2021 Apr 5.

Department of Hematological Biology, Pitié-Salpêtrière Hospital, Paris Sorbonne University, Paris, France.

Mastocytosis is a neoplasm characterized by an accumulation of mast cells in various organs and increased risk for severe anaphylaxis in patients with concomitant allergies. Coronavirus disease 2019 (COVID-19) is a pandemic that is associated with a relatively high rate of severe lung disease and mortality. The mortality is particularly high in those with certain comorbidities and increases with age. Recently, several companies have developed an effective vaccination against COVID-19. Although the reported frequency of severe side effects is low, there is an emerging discussion about the safety of COVID-19 vaccination in patients with severe allergies and mastocytosis. However, even in these patients, severe adverse reactions are rare. We therefore recommend the broad use of COVID-19 vaccination in patients with mastocytosis on a global basis. The only well-established exception is a known or suspected allergy against a constituent of the vaccine. Safety measures, including premedication and postvaccination observation, should be considered in all patients with mastocytosis, depending on the individual personal risk and overall situation in each case. The current article provides a summary of published data, observations, and expert opinion that form the basis of these recommendations.
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http://dx.doi.org/10.1016/j.jaip.2021.03.041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8019658PMC
June 2021

Molecular Background, Clinical Features and Management of Pediatric Mastocytosis: Status 2021.

Int J Mol Sci 2021 Mar 4;22(5). Epub 2021 Mar 4.

Division of Hematology and Hemostaseology, Department of Internal Medicine I, Medical University of Vienna, 1090 Vienna, Austria.

Pediatric mastocytosis is a heterogeneous disease characterized by accumulation of mast cells in the skin and less frequently in other organs. Somatic or germline mutations in the proto-oncogene are detected in most patients. Cutaneous mastocytosis is the most common form of the disease in children. In the majority of cases, skin lesions regress spontaneously around puberty. However, in few patients, mastocytosis is not a self-limiting disease, but persists into adulthood and can show signs of systemic involvement, especially when skin lesions are small-sized and monomorphic. Children with mastocytosis often suffer from mast cell mediator-related symptoms. Severe hypersensitivity reactions can also occur, mostly in patients with extensive skin lesions and blistering. In a substantial number of these cases, the triggering factor of anaphylaxis remains unidentified. Management of pediatric mastocytosis is mainly based on strict avoidance of triggers, treatment with H1 and H2 histamine receptor blockers, and equipment of patients and their families with epinephrine auto-injectors for use in severe anaphylactic reactions. Advanced systemic mastocytosis occurs occasionally. All children with mastocytosis require follow-up examinations. A bone marrow investigation is performed when advanced systemic mastocytosis is suspected and has an impact on therapy or when cutaneous disease persists into adulthood.
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http://dx.doi.org/10.3390/ijms22052586DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7961542PMC
March 2021

Epigenetic Changes in Neoplastic Mast Cells and Potential Impact in Mastocytosis.

Int J Mol Sci 2021 Mar 15;22(6). Epub 2021 Mar 15.

Department of Allergology, Medical University of Gdansk, 80-211 Gdansk, Poland.

Systemic mastocytosis (SM) is a hematologic neoplasm with abnormal accumulation of mast cells in various organ systems such as the bone marrow, other visceral organs and skin. So far, only little is known about epigenetic changes contributing to the pathogenesis of SM. In the current article, we provide an overview of epigenetic changes that may occur and be relevant to mastocytosis, including mutations in genes involved in epigenetic processes, such as , and , and global and gene-specific methylation patterns in neoplastic cells. Moreover, we discuss methylation-specific pathways and other epigenetic events that may trigger disease progression in mast cell neoplasms. Finally, we discuss epigenetic targets and the effects of epigenetic drugs, such as demethylating agents and BET-targeting drugs, on growth and viability of neoplastic mast cells. The definitive impact of these targets and the efficacy of epigenetic therapies in advanced SM need to be explored in future preclinical studies and clinical trials.
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http://dx.doi.org/10.3390/ijms22062964DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7999363PMC
March 2021

Mediator-Related Symptoms and Anaphylaxis in Children with Mastocytosis.

Int J Mol Sci 2021 Mar 7;22(5). Epub 2021 Mar 7.

Department of Internal Medicine I, Division of Hematology & Hemostaseology, Medical University of Vienna, 1090 Vienna, Austria.

Mastocytosis is characterized by the pathological accumulation of mast cells (MC) in various organs. In these patients, MC may degranulate and thereby contribute to clinical symptoms, especially when a concomitant allergy is present. However, MC activation can not only be induced by high-affinity receptors for IgE, but also by anaphylatoxins, neuropeptides, IgG immune complexes, complement-components, drugs, products of bacteria or parasites, as well as physical factors such as heat, cold, vibration, stress, sun, or physical effort. Symptoms due to mediators released by activated MC may develop in adults suffering from systemic mastocytosis, but also evolve in children who usually have cutaneous mastocytosis (CM). Clinically, CM is otherwise characterized by typical brown, maculopapular skin lesions or mastocytoma associated with a positive Darier's sign. Pruritus and flushing are common and blistering may also be recorded, especially in diffuse CM (DCM). Pediatric patients with mastocytosis may also have gastrointestinal, respiratory, and neurologic complaints. Although anaphylaxis is not a typical finding, pediatric patients with massive skin involvement and high tryptase levels have a relatively high risk to develop anaphylaxis. This paper reviews MC mediator-related symptoms and anaphylaxis in children with mastocytosis, with special emphasis on risk factors, triggers, and management.
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http://dx.doi.org/10.3390/ijms22052684DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7962052PMC
March 2021

Impact of gene variants on iron overload, overall survival and leukemia-free survival in myelodysplastic syndromes.

Am J Cancer Res 2021 1;11(3):955-967. Epub 2021 Mar 1.

Department of Medicine I, Division of Hematology & Hemostaseology, Medical University of Vienna Vienna 1090, Austria.

Although iron overload is a clinical challenge, little is known about the clinical impact of -variants in myelodysplastic syndromes (MDS) to date. We analyzed the status in 167 MDS patients and 494 healthy controls. One or more of the 3 -variants (H63D, C282Y, S65C) were found in 65/167 (38.9%) MDS patients and in 164/494 (33.2%) controls. At diagnosis, the median serum ferritin levels were higher in MDS patients with -variants (409 µg/L; range: 23-7415) compared to those without -variants (346.5 µg/L; range: 10-5450) (P=0.62). Moreover, '-mutated' patients had a slightly faster increase in serum ferritin in follow up examinations. The percentage of patients with -variants was higher in refractory anemia (RA) (22/53=41.5%) or RA with ring sideroblasts (RARS) (17/39=43.6%) compared to RA with excess of blasts (RAEB) (16/46=34.8%) or RAEB in transformation (RAEB-T) (5/17=29.4%). Differences were also detectable when comparing low- and high-risk MDS variants defined by the World Health Organization classification. There was no significant correlation between -variants and MDS-related somatic mutations. Progression-free survival was substantially longer in patients with -variants compared to those without -variants H63D and C282Y (P=0.089). Together, the -variants H63D and C282Y are frequently detected in Austrian MDS patients. These patients have substantially higher ferritin levels at diagnosis, accumulate iron slightly faster and have a better progression-free survival than non-mutated patients.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7994158PMC
March 2021

Phenotypic characterization of leukemia-initiating stem cells in chronic myelomonocytic leukemia.

Leukemia 2021 Mar 30. Epub 2021 Mar 30.

Department of Medicine I, Division of Hematology and Hemostaseology, Medical University of Vienna, Vienna, Austria.

Chronic myelomonocytic leukemia (CMML) is a stem cell-derived neoplasm characterized by dysplasia, uncontrolled expansion of monocytes, and substantial risk to transform to secondary acute myeloid leukemia (sAML). So far, little is known about CMML-initiating cells. We found that leukemic stem cells (LSC) in CMML reside in a CD34/CD38 fraction of the malignant clone. Whereas CD34/CD38 cells engrafted NSGS mice with overt CMML, no CMML was produced by CD34/CD38 progenitors or the bulk of CD34 monocytes. CMML LSC invariably expressed CD33, CD117, CD123 and CD133. In a subset of patients, CMML LSC also displayed CD52, IL-1RAP and/or CLL-1. CMML LSC did not express CD25 or CD26. However, in sAML following CMML, the LSC also expressed CD25 and high levels of CD114, CD123 and IL-1RAP. No correlations between LSC phenotypes, CMML-variant, mutation-profiles, or clinical course were identified. Pre-incubation of CMML LSC with gemtuzumab-ozogamicin or venetoclax resulted in decreased growth and impaired engraftment in NSGS mice. Together, CMML LSC are CD34/CD38 cells that express a distinct profile of surface markers and target-antigens. During progression to sAML, LSC acquire or upregulate certain cytokine receptors, including CD25, CD114 and CD123. Characterization of CMML LSC should facilitate their enrichment and the development of LSC-eradicating therapies.
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http://dx.doi.org/10.1038/s41375-021-01227-zDOI Listing
March 2021

Presence of viremia during febrile neutropenic episodes in patients undergoing chemotherapy for malignant neoplasms.

Am J Hematol 2021 06 3;96(6):719-726. Epub 2021 May 3.

St.Anna Children's Cancer Research Institute (CCRI), Vienna, Austria.

The importance of viral infections as a leading cause of morbidity and mortality is well documented in severely immunosuppressed patients undergoing allogeneic stem cell transplantation. By contrast, viral infections generally receive less attention in patients with malignant disorders undergoing chemotherapy, where the onset of neutropenic fever is mostly associated with bacterial or fungal infections, and screening for viral infections is not routinely performed. To address the occurrence of invasive viral infections in a clinical setting commonly associated with less pronounced immunosuppression, we have prospectively screened 237 febrile neutropenic episodes in pediatric (n = 77) and adult (n = 69) patients undergoing intensive chemotherapy, primarily for treatment of acute leukemia. Serial peripheral blood specimens were tested by RQ-PCR assays for the presence and quantity of the clinically relevant viruses CMV, EBV, HHV6 and HAdV, commonly reactivated in highly immunocompromised patients. Viremia was documented in 36 (15%) episodes investigated, including the detection of HHV6 (n = 14), EBV (n = 15), CMV (n = 6), or HAdV (n = 1). While low or intermediate levels of viremia (<10 virus copies/mL) were commonly associated with bacterial or fungal co-infection, viremia at higher levels (>10 copies/mL) was documented in patients without evidence for other infections, raising the possibility that at least in some instances the onset of fever may have been attributable to the virus detected. The observations suggest that viral infections, potentially resulting from reactivation, might also play a clinically relevant role in patients receiving chemotherapy for treatment of malignant neoplasms, and routine screening for viremia in this clinical setting might be warranted.
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http://dx.doi.org/10.1002/ajh.26177DOI Listing
June 2021

Proceedings from the Inaugural American Initiative in Mast Cell Diseases (AIM) Investigator Conference.

J Allergy Clin Immunol 2021 Jun 11;147(6):2043-2052. Epub 2021 Mar 11.

Division of Allergy and Immunology, University of Michigan, Ann Arbor, Mich.

The American Initiative in Mast Cell Diseases (AIM) held its inaugural investigator conference at Stanford University School of Medicine in May 2019. The overarching goal of this meeting was to establish a Pan-American organization of physicians and scientists with multidisciplinary expertise in mast cell disease. To serve this unmet need, AIM envisions a network where basic, translational, and clinical researchers could establish collaborations with both academia and biopharma to support the development of new diagnostic methods, enhanced understanding of the biology of mast cells in human health and disease, and the testing of novel therapies. In these AIM proceedings, we highlight selected topics relevant to mast cell biology and provide updates regarding the recently described hereditary alpha-tryptasemia. In addition, we discuss the evaluation and treatment of mast cell activation (syndromes), allergy and anaphylaxis in mast cell disorders, and the clinical and biologic heterogeneity of the more indolent forms of mastocytosis. Because mast cell disorders are relatively rare, AIM hopes to achieve a coordination of scientific efforts not only in the Americas but also in Europe by collaborating with the well-established European Competence Network on Mastocytosis.
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http://dx.doi.org/10.1016/j.jaci.2021.03.008DOI Listing
June 2021

Genetic Regulation of Tryptase Production and Clinical Impact: Hereditary Alpha Tryptasemia, Mastocytosis and Beyond.

Int J Mol Sci 2021 Feb 28;22(5). Epub 2021 Feb 28.

Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of Vienna, 1090 Vienna, Austria.

Tryptase is a serine protease that is predominantly produced by tissue mast cells (MCs) and stored in secretory granules together with other pre-formed mediators. MC activation, degranulation and mediator release contribute to various immunological processes, but also to several specific diseases, such as IgE-dependent allergies and clonal MC disorders. Biologically active tryptase tetramers primarily derive from the two genes (encoding β-tryptase) and (encoding either α- or β-tryptase). Based on the most common gene copy numbers, three genotypes, 0α:4β, 1α:3β and 2α:2β, were defined as "canonical". About 4-6% of the general population carry germline -α copy number gains (2α:3β, 3α:2β or more α-extra-copies), resulting in elevated basal serum tryptase levels. This condition has recently been termed hereditary alpha tryptasemia (HαT). Although many carriers of HαT appear to be asymptomatic, a number of more or less specific symptoms have been associated with HαT. Recent studies have revealed a significantly higher HαT prevalence in patients with systemic mastocytosis (SM) and an association with concomitant severe Hymenoptera venom-induced anaphylaxis. Moreover, HαT seems to be more common in idiopathic anaphylaxis and MC activation syndromes (MCAS). Therefore, genotyping should be included in the diagnostic algorithm in patients with symptomatic SM, severe anaphylaxis or MCAS.
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http://dx.doi.org/10.3390/ijms22052458DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7957558PMC
February 2021

Physiology and pathology of eosinophils: Recent developments: Summary of the Focus Workshop Organized by DGAKI.

Scand J Immunol 2021 Jun 11;93(6):e13032. Epub 2021 Mar 11.

Deptment of Dermatology and Allergology Biederstein, Technical University Munich (TUM), Munich, Germany.

Over the last century, eosinophils have been regarded ambiguously either as 'friends' or 'foes'. Recent developments have greatly enhanced our understanding of the role and function of eosinophils in health and disease. Pathogenic eosinophilic inflammation can lead to severe diseases in various organs, such as the gastrointestinal tract, airways, heart and skin. In a 2-day focus workshop of the German Society for Allergology and Clinical Immunology (DGAKI), the state of the art was discussed and practical recommendations for diagnosis and treatment of eosinophilic diseases, with a particular focus on new biologics, such as anti-interleukin 5 and anti-interleukin 5R, were derived.
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http://dx.doi.org/10.1111/sji.13032DOI Listing
June 2021

Precision Medicine in Hematology 2021: Definitions, Tools, Perspectives, and Open Questions.

Hemasphere 2021 Mar 17;5(3):e536. Epub 2021 Feb 17.

Department of Medicine I, Division of Hematology & Hemostaseology, Medical University of Vienna, Austria.

During the past few years, our understanding of molecular mechanisms and cellular interactions relevant to malignant blood cell disorders has improved substantially. New insights include a detailed knowledge about disease-initiating exogenous factors, endogenous (genetic, somatic, epigenetic) elicitors or facilitators of disease evolution, and drug actions and interactions that underlie efficacy and adverse event profiles in defined cohorts of patients. As a result, precision medicine and personalized medicine are rapidly growing new disciplines that support the clinician in making the correct diagnosis, in predicting outcomes, and in optimally selecting patients for interventional therapies. In addition, precision medicine tools are greatly facilitating the development of new drugs, therapeutic approaches, and new multiparametric prognostic scoring models. However, although the emerging roles of precision medicine and personalized medicine in hematology and oncology are clearly visible, several questions remain. For example, it remains unknown how precision medicine tools can be implemented in healthcare systems and whether all possible approaches are also affordable. In addition, there is a need to define terminologies and to relate these to specific and context-related tools and strategies in basic and applied science. To discuss these issues, a working conference was organized in September 2019. The outcomes of this conference are summarized herein and include a proposal for definitions, terminologies, and applications of precision and personalized medicine concepts and tools in hematologic neoplasms. We also provide proposals aimed at reducing costs, thereby making these applications affordable in daily practice.
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http://dx.doi.org/10.1097/HS9.0000000000000536DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7892291PMC
March 2021

Clinical Impact of Skin Lesions in Mastocytosis: A Multicenter Study of the European Competence Network on Mastocytosis.

J Invest Dermatol 2021 Jul 11;141(7):1719-1727. Epub 2021 Feb 11.

Department of Internal Medicine IV, Oncology, Hematology, Hemostaseology, University Halle (Saale), Halle (Saale), Germany.

Mastocytosis is a rare neoplasm characterized by the expansion and accumulation of mast cells in various organ systems. Systemic mastocytosis (SM) may or may not present with cutaneous lesions. To examine the frequency and clinical impact of cutaneous involvement, data on 1,510 patients with mastocytosis collected in the registry of the European Competence Network on Mastocytosis were analyzed. Cutaneous involvement was found in 1,195 of 1,510 patients (79.1%). Of these, 286 had cutaneous mastocytosis, and 721 had SM with skin involvement. Adult patients with skin involvement who did not have a bone marrow examination (n = 188) were defined as having mastocytosis in the skin. In 315 patients, SM without skin involvement was found. The percentage of cases with cutaneous involvement was higher in indolent SM (100%) and smoldering SM (87.9%) compared to aggressive SM (46.8%) or mast cell leukemia (38.5%). After a median follow-up of 5.6 years, no patient with cutaneous mastocytosis had died, but 2.6% of the patients with mastocytosis in the skin, 5.7% of the patients with SM with skin involvement, and 28.95% of the patients with SM without skin involvement had died. Overall survival was longer in patients with skin involvement (cutaneous mastocytosis and/or mastocytosis in the skin and/or SM with skin involvement) than in patients with SM without skin involvement (P < 0.0001). These data argue for a thorough examination of both the skin and bone marrow in adult patients with mastocytosis.
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http://dx.doi.org/10.1016/j.jid.2020.12.030DOI Listing
July 2021

Degradation of BRD4 - a promising treatment approach not only for hematologic but also for solid cancer.

Am J Cancer Res 2021 1;11(2):530-545. Epub 2021 Feb 1.

Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of Vienna Austria.

Bromodomain (BRD) and extra-terminal (BET) proteins are epigenetic readers that regulate gene expression and promote cancer evolution. Pharmacological inactivation of BRD4 has recently been introduced as a promising anti-neoplastic approach that targets MYC oncogene expression. However, resistance against BRD4-targeting drugs has been described. We compared the efficacy of the small-molecule-type BET BRD inhibitor JQ1 with the recently developed BET protein degraders dBET1 and dBET6 in colon, breast, melanoma, ovarian, lung and prostate cancer cell lines. As determined by qPCR, all BRD4 targeting drugs dose-dependently decreased MYC expression, with dBET6 introducing the strongest downregulation of MYC. This correlated with the anti-proliferative activity of these drugs, which was at least one order of magnitude higher for dBET6 (IC 0.001-0.5 µM) than for dBET1 or JQ1 (IC 0.5-5 µM). Interestingly, when combined with commonly used cytotoxic therapeutics, dBET6 was found to promote anti-neoplastic effects and to counteract chemoresistance in most cancer cell lines. Moreover, JQ1 and both BET degraders strongly downregulated baseline and interferon-gamma induced expression of the immune checkpoint molecule PD-L1 in all cancer cell lines. Together, our data suggest that dBET6 outperforms first-generation BRD4 targeting drugs like dBET1 and JQ1, and decreases chemoresistance and immune resistance of cancer.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7868748PMC
February 2021

miRNome profiling of LSC-enriched CD34CD38CD26 fraction in Ph CML-CP samples from Argentinean patients: a potential new pharmacogenomic tool.

Front Pharmacol 2020 11;11:612573. Epub 2021 Jan 11.

Centro de Investigaciones Oncológicas-Fundación Cáncer, Ciudad Autónoma de Buenos Aires, Argentina.

Chronic myeloid leukemia (CML) is a myeloid stem cell neoplasm characterized by an expansion of myeloid progenitor cells and the presence of BCR-ABL1 oncoprotein. Since the introduction of specific BCR-ABL1 tyrosine kinase inhibitors (TKI), overall survival has improved significantly. However, under long-term therapy patients may have residual disease that originates from TKI-resistant leukemic stem cells (LSC). In this work, we analyzed the miRNome of LSC-enriched CD34CD38CD26 and normal hematopoietic stem cells (HSC) fractions obtained from the same chronic phase (CP) CML patients, and stem and progenitor cells obtained from healthy donors (HD) by next-generation sequencing. We detected a global decrease of microRNA levels in LSC-enriched CD34CD38CD26 and HSC fractions from CML-CP patients, and decreased levels of microRNAs and snoRNAs from a genomic cluster in chromosome 14, suggesting a mechanism of silencing of multiple non-coding RNAs. Surprisingly, HSC from CML-CP patients, despite the absence of expression, showed an altered miRNome. We confirmed by RT-qPCR that the levels of miR-196a-5p were increased more than nine-fold in CD26 ( ) vs. CD26 ( ) CD34CD38 fractions from CML-CP patients at diagnosis, and analysis revealed a significant association to lipid metabolism and hematopoiesis functions. In the light of recent descriptions of increased oxidative metabolism in CML LSC-enriched fractions, these results serve as a guide for future functional studies that evaluate the role of microRNAs in this process. Metabolic vulnerabilities in LSCs open the road for new therapeutic strategies. This is the first report of the miRNome of CML-CP CD34CD38 fractions that distinguishes between CD26 ( ) and their CD26 ( ) counterparts, providing valuable data for future studies.
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http://dx.doi.org/10.3389/fphar.2020.612573DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7869017PMC
January 2021
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