Publications by authors named "Charlotte Niemeyer"

220 Publications

Severe adverse events during sirolimus "off-label" therapy for vascular anomalies.

Pediatr Blood Cancer 2021 Feb 13:e28936. Epub 2021 Feb 13.

Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Objectives: Clinical studies have shown low toxicity and a favorable safety profile for sirolimus in vascular anomalies. Here, we describe severe adverse events (SAEs) observed during "off-label use" for vascular anomalies.

Methods: We performed a retrospective, multicenter chart review for SAEs during "off-label" sirolimus therapy for vascular anomalies and analyzed these cases by a predesigned workflow.

Results: We identified 17 SAEs in 14 patients diagnosed with generalized lymphatic anomaly (n = 4), Gorham-Stout disease (n = 2), central conducting lymphatic anomaly (n = 1), lymphatic malformation (n = 4), tufted angioma (n = 1), kaposiform hemangioendothelioma (n = 1), and venous malformation in a patient with CLOVES syndrome (n = 1). Three patients presented two SAEs each. The age at initiation of sirolimus therapy was under 2 years (n = 5), 2-6 years (n = 5), and older than 12 years (n = 4). SAEs occurred during the first 3 months of sirolimus therapy (n = 7), between 3 and 12 months (n = 7) and after 1 year of therapy (n = 3). The most frequent SAE was viral pneumonia (n = 8) resulting in one death due to a metapneumovirus infection in a 3 months old and a generalized adenovirus infection in a 28-month-old child. Sirolimus blood level at the time of SAEs ranged between 2.7 and 21 ng/L. Five patients were on antibiotic prophylaxis.

Conclusions: Most SAEs are observed in the first year of sirolimus therapy; however, SAEs can also occur after a longer treatment period. SAEs are potentially life threatening, especially in early infancy. Presence of other risk factors, that is, underlying vascular anomaly or immune status, may contribute to the risk of SAEs. Sirolimus is an important therapeutic option for vascular anomalies, but patients and physicians need to be aware that adequate monitoring is necessary, especially in patients with complex lymphatic anomalies that are overrepresented in our cohort of SAEs.
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http://dx.doi.org/10.1002/pbc.28936DOI Listing
February 2021

High-resolution pediatric reference intervals for 15 biochemical analytes described using fractional polynomials.

Clin Chem Lab Med 2021 Feb 9. Epub 2021 Feb 9.

Department of Pediatrics and Adolescent Medicine, University Hospital Erlangen, Erlangen, Germany.

Objectives: Assessment of children's laboratory test results requires consideration of the extensive changes that occur during physiological development and result in pronounced sex- and age-specific dynamics in many biochemical analytes. Pediatric reference intervals have to account for these dynamics, but ethical and practical challenges limit the availability of appropriate pediatric reference intervals that cover children from birth to adulthood. We have therefore initiated the multi-center data-driven project (Next-Generation Pediatric Reference Intervals) to create pediatric reference intervals using data from laboratory information systems.

Methods: We analyzed laboratory test results from 638,683 patients (217,883-982,548 samples per analyte, a median of 603,745 test results per analyte, and 10,298,067 test results in total) performed during patient care in 13 German centers. Test results from children with repeat measurements were discarded, and we estimated the distribution of physiological test results using a validated statistical approach ().

Results: We report continuous pediatric reference intervals and percentile charts for alanine transaminase, aspartate transaminase, lactate dehydrogenase, alkaline phosphatase, γ-glutamyl-transferase, total protein, albumin, creatinine, urea, sodium, potassium, calcium, chloride, anorganic phosphate, and magnesium. Reference intervals are provided as tables and fractional polynomial functions (i.e., mathematical equations) that can be integrated into laboratory information systems. Additionally, -scores and percentiles enable the normalization of test results by age and sex to facilitate their interpretation across age groups.

Conclusions: The provided reference intervals and percentile charts enable precise assessment of laboratory test results in children from birth to adulthood. Our findings highlight the pronounced dynamics in many biochemical analytes in neonates, which require particular consideration in reference intervals to support clinical decision making most effectively.
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http://dx.doi.org/10.1515/cclm-2020-1371DOI Listing
February 2021

Long non-coding RNAs as novel therapeutic targets in juvenile myelomonocytic leukemia.

Sci Rep 2021 Feb 2;11(1):2801. Epub 2021 Feb 2.

Department of Pediatric Hematology-Oncology and Stem Cell Transplantation, Ghent University Hospital, Ghent, Belgium.

Juvenile myelomonocytic leukemia (JMML) treatment primarily relies on hematopoietic stem cell transplantation and results in long-term overall survival of 50-60%, demonstrating a need to develop novel treatments. Dysregulation of the non-coding RNA transcriptome has been demonstrated before in this rare and unique disorder of early childhood. In this study, we investigated the therapeutic potential of targeting overexpressed long non-coding RNAs (lncRNAs) in JMML. Total RNA sequencing of bone marrow and peripheral blood mononuclear cell preparations from 19 untreated JMML patients and three healthy children revealed 185 differentially expressed lncRNA genes (131 up- and 54 downregulated). LNA GapmeRs were designed for 10 overexpressed and validated lncRNAs. Molecular knockdown (≥ 70% compared to mock control) after 24 h of incubation was observed with two or more independent GapmeRs in 6 of them. For three lncRNAs (lnc-THADA-4, lnc-ACOT9-1 and NRIR) knockdown resulted in a significant decrease of cell viability after 72 h of incubation in primary cultures of JMML mononuclear cells, respectively. Importantly, the extent of cellular damage correlated with the expression level of the lncRNA of interest. In conclusion, we demonstrated in primary JMML cell cultures that knockdown of overexpressed lncRNAs such as lnc-THADA-4, lnc-ACOT9-1 and NRIR may be a feasible therapeutic strategy.
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http://dx.doi.org/10.1038/s41598-021-82509-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7854679PMC
February 2021

CircRNAs Dysregulated in Juvenile Myelomonocytic Leukemia: CircMCTP1 Stands Out.

Front Cell Dev Biol 2020 6;8:613540. Epub 2021 Jan 6.

Department of Molecular Medicine, University of Padova, Padua, Italy.

Juvenile myelomonocytic leukemia (JMML), a rare myelodysplastic/myeloproliferative neoplasm of early childhood, is characterized by clonal growth of RAS signaling addicted stem cells. JMML subtypes are defined by specific RAS pathway mutations and display distinct gene, microRNA (miRNA) and long non-coding RNA expression profiles. Here we zoom in on circular RNAs (circRNAs), molecules that, when abnormally expressed, may participate in malignant deviation of cellular processes. CirComPara software was used to annotate and quantify circRNAs in RNA-seq data of a "discovery cohort" comprising 19 JMML patients and 3 healthy donors (HD). In an independent set of 12 JMML patients and 6 HD, expression of 27 circRNAs was analyzed by qRT-PCR. CircRNA-miRNA-gene networks were reconstructed using circRNA function prediction and gene expression data. We identified 119 circRNAs dysregulated in JMML and 59 genes showing an imbalance of the circular and linear products. Our data indicated also circRNA expression differences among molecular subgroups of JMML. Validation of a set of deregulated circRNAs in an independent cohort of JMML patients confirmed the down-regulation of circOXNAD1 and circATM, and a marked up-regulation of circLYN, circAFF2, and circMCTP1. A new finding in JMML links up-regulated circMCTP1 with known tumor suppressor miRNAs. This and other predicted interactions with miRNAs connect dysregulated circRNAs to regulatory networks. In conclusion, this study provides insight into the circRNAome of JMML and paves the path to elucidate new molecular disease mechanisms putting forward circMCTP1 up-regulation as a robust example.
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http://dx.doi.org/10.3389/fcell.2020.613540DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7815690PMC
January 2021

Prevalence of SARS-CoV-2 Infection in Children and Their Parents in Southwest Germany.

JAMA Pediatr 2021 Jan 22. Epub 2021 Jan 22.

Department of Infectious Diseases, Virology, Heidelberg University, Heidelberg, Germany.

Importance: School and daycare closures were enforced as measures to confine the novel coronavirus disease 2019 (COVID-19) pandemic, based on the assumption that young children may play a key role in severe acute respiratory coronavirus 2 (SARS-CoV-2) spread. Given the grave consequences of contact restrictions for children, a better understanding of their contribution to the COVID-19 pandemic is of great importance.

Objective: To describe the rate of SARS-CoV-2 infections and the seroprevalence of SARS-CoV-2 antibodies in children aged 1 to 10 years, compared with a corresponding parent of each child, in a population-based sample.

Design, Setting, And Participants: This large-scale, multicenter, cross-sectional investigation (the COVID-19 BaWü study) enrolled children aged 1 to 10 years and a corresponding parent between April 22 and May 15, 2020, in southwest Germany.

Exposures: Potential exposure to SARS-CoV-2.

Main Outcomes And Measures: The main outcomes were infection and seroprevalence of SARS-CoV-2. Participants were tested for SARS-CoV-2 RNA from nasopharyngeal swabs by reverse transcription-polymerase chain reaction and SARS-CoV-2 specific IgG antibodies in serum by enzyme-linked immunosorbent assays and immunofluorescence tests. Discordant results were clarified by electrochemiluminescence immunoassays, a second enzyme-linked immunosorbent assay, or an in-house Luminex-based assay.

Results: This study included 4964 participants: 2482 children (median age, 6 [range, 1-10] years; 1265 boys [51.0%]) and 2482 parents (median age, 40 [range, 23-66] years; 615 men [24.8%]). Two participants (0.04%) tested positive for SARS-CoV-2 RNA. The estimated SARS-CoV-2 seroprevalence was low in parents (1.8% [95% CI, 1.2-2.4%]) and 3-fold lower in children (0.6% [95% CI, 0.3-1.0%]). Among 56 families with at least 1 child or parent with seropositivity, the combination of a parent with seropositivity and a corresponding child with seronegativity was 4.3 (95% CI, 1.19-15.52) times higher than the combination of a parent who was seronegative and a corresponding child with seropositivity. We observed virus-neutralizing activity for 66 of 70 IgG-positive serum samples (94.3%).

Conclusions And Relevance: In this cross-sectional study, the spread of SARS-CoV-2 infection during a period of lockdown in southwest Germany was particularly low in children aged 1 to 10 years. Accordingly, it is unlikely that children have boosted the pandemic. This SARS-CoV-2 prevalence study, which appears to be the largest focusing on children, is instructive for how ad hoc mass testing provides the basis for rational political decision-making in a pandemic.
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http://dx.doi.org/10.1001/jamapediatrics.2021.0001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7823424PMC
January 2021

Outcomes of patients with hematologic malignancies and COVID-19: a report from the ASH Research Collaborative Data Hub.

Blood Adv 2020 12;4(23):5966-5975

Division of Hematology/Oncology, Department of Medicine, St. Michael's Hospital, Toronto, ON, Canada.

Coronavirus disease 2019 (COVID-19) is an illness resulting from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that emerged in late 2019. Patients with cancer, and especially those with hematologic malignancies, may be at especially high risk of adverse outcomes, including mortality resulting from COVID-19 infection. The ASH Research Collaborative COVID-19 Registry for Hematology was developed to study features and outcomes of COVID-19 infection in patients with underlying blood disorders, such as hematologic malignancies. At the time of this report, data from 250 patients with blood cancers from 74 sites around the world had been entered into the registry. The most commonly represented malignancies were acute leukemia (33%), non-Hodgkin lymphoma (27%), and myeloma or amyloidosis (16%). Patients presented with a myriad of symptoms, most frequently fever (73%), cough (67%), dyspnea (50%), and fatigue (40%). Use of COVID-19-directed therapies, such as hydroxychloroquine (n = 76) or azithromycin (n = 59), was common. Overall mortality was 28%. Patients with a physician-estimated prognosis from the underlying hematologic malignancy of <12 months at the time of COVID-19 diagnosis and those with relapsed/refractory disease experienced a higher proportion of moderate/severe COVID-19 disease and death. In some instances, death occurred after a decision was made to forgo intensive care unit admission in favor of a palliative approach. Taken together, these data support the emerging consensus that patients with hematologic malignancies experience significant morbidity and mortality resulting from COVID-19 infection. Batch submissions from sites with high incidence of COVID-19 infection are planned to support future analyses.
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http://dx.doi.org/10.1182/bloodadvances.2020003170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7724912PMC
December 2020

A distinct CD38+CD45RA+ population of CD4+, CD8+, and double-negative T cells is controlled by FAS.

J Exp Med 2021 Feb;218(2)

Institute for Immunodeficiency, Center for Chronic Immunodeficiency, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

The identification and characterization of rare immune cell populations in humans can be facilitated by their growth advantage in the context of specific genetic diseases. Here, we use autoimmune lymphoproliferative syndrome to identify a population of FAS-controlled TCRαβ+ T cells. They include CD4+, CD8+, and double-negative T cells and can be defined by a CD38+CD45RA+T-BET- expression pattern. These unconventional T cells are present in healthy individuals, are generated before birth, are enriched in lymphoid tissue, and do not expand during acute viral infection. They are characterized by a unique molecular signature that is unambiguously different from other known T cell differentiation subsets and independent of CD4 or CD8 expression. Functionally, FAS-controlled T cells represent highly proliferative, noncytotoxic T cells with an IL-10 cytokine bias. Mechanistically, regulation of this physiological population is mediated by FAS and CTLA4 signaling, and its survival is enhanced by mTOR and STAT3 signals. Genetic alterations in these pathways result in expansion of FAS-controlled T cells, which can cause significant lymphoproliferative disease.
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http://dx.doi.org/10.1084/jem.20192191DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7658692PMC
February 2021

International Consensus Definition of DNA Methylation Subgroups in Juvenile Myelomonocytic Leukemia.

Clin Cancer Res 2021 Jan 2;27(1):158-168. Epub 2020 Nov 2.

Section Translational Cancer Epigenomics, Division Translational Medical Oncology, German Cancer Research Center (DKFZ) & National Center for Tumor Diseases (NCT), Heidelberg, Germany.

Purpose: Known clinical and genetic markers have limitations in predicting disease course and outcome in juvenile myelomonocytic leukemia (JMML). DNA methylation patterns in JMML have correlated with outcome across multiple studies, suggesting it as a biomarker to improve patient stratification. However, standardized approaches to classify JMML on the basis of DNA methylation patterns are lacking. We, therefore, sought to define an international consensus for DNA methylation subgroups in JMML and develop classification methods for clinical implementation.

Experimental Design: Published DNA methylation data from 255 patients with JMML were used to develop and internally validate a classifier model. Accuracy across platforms (EPIC-arrays and MethylSeq) was tested using a technical validation cohort (32 patients). The suitability of both methods for single-patient classification was demonstrated using an independent cohort (47 patients).

Results: Analysis of pooled, published data established three DNA methylation subgroups as a standard. Unfavorable prognostic parameters ( mutation, elevated fetal hemoglobin, and older age) were significantly enriched in the high methylation (HM) subgroup. A classifier was then developed that predicted subgroups with 98% accuracy across different technological platforms. Applying the classifier to an independent validation cohort confirmed an association of HM with secondary mutations, high relapse incidence, and inferior overall survival (OS), while the low methylation subgroup was associated with a favorable disease course. Multivariable analysis established DNA methylation subgroups as the only significant factor predicting OS.

Conclusions: This study provides an international consensus definition for DNA methylation subgroups in JMML. We developed and validated methods which will facilitate the design of risk-stratified clinical trials in JMML.
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http://dx.doi.org/10.1158/1078-0432.CCR-20-3184DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7785676PMC
January 2021

Case Report: Hepatic Adenoma in a Child With a Congenital Extrahepatic Portosystemic Shunt.

Front Pediatr 2020 25;8:501. Epub 2020 Aug 25.

Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Faculty of Medicine, Medical Center-University of Freiburg, University of Freiburg, Freiburg im Breisgau, Germany.

Congenital extrahepatic portosystemic shunts (CEPS), previously also described as Abernethy malformations, are rare malformations in which the extrahepatic portal system directly communicates with the vena cava inferior, thereby bypassing the liver. A hypoplastic portal vein (PV) exists in most cases. CEPS have been associated with the development of liver nodules, ranging from mostly focal nodular hyperplasia (FNH) to hepatic adenoma (HA) and even hepatocellular carcinoma (HCC). Tumor development in CEPS may be due to changes in perfusion pressures, oxygen supply or endocrine imbalances. It is important to rule out CEPS in children with liver tumors, because resection could impede future shunt occlusion procedures, and benign masses may regress after shunt occlusion. Here, we review the case of a 9-years-old male with CEPS and hepatic nuclear Factor 1-alpha (HNF-1-alpha) inactivated HA to raise awareness of this condition and review histopathological changes in the liver of CEPS.
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http://dx.doi.org/10.3389/fped.2020.00501DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7477041PMC
August 2020

Association of Country-Specific Socioeconomic Factors With Survival of Patients Who Experience Severe Classic Acute Graft-vs.-Host Disease After Allogeneic Hematopoietic Cell Transplantation. An Analysis From the Transplant Complications Working Party of the EBMT.

Front Immunol 2020 23;11:1537. Epub 2020 Jul 23.

Department of Haematology, Oncology and Internal Medicine, Medical Uniwersity of Warsaw, Warsaw, Poland.

Acute graft-vs.-host disease (aGvHD) is one of the most frequent causes of transplant-related mortality (TRM) after allogeneic hematopoietic cell transplantation (alloHCT). Its treatment is complex and costly. The aim of this study was to retrospectively analyze the impact of country-specific socioeconomic factors on outcome of patients who experience severe aGvHD. Adults with hematological malignancies receiving alloHCT from either HLA-matched siblings ( = 1,328) or unrelated donors ( = 2,824) developing grade 3 or 4 aGvHD were included. In univariate analysis, the probability of TRM at 2 years was increased for countries with lower current Health Care Expenditure (HCE, = 0.04), lower HCE as % of Gross Domestic Product per capita ( = 0.003) and lower values of the Human Development Index ( = 0.02). In a multivariate model, the risk of TRM was most strongly predicted by current HCE (HR = 0.76, = 0.006). HCE >median was also associated with reduced risk of the overall mortality (HR 0.73, = 0.0006) and reduced risk of treatment failure (either relapse or TRM; HR 0.77, = 0.004). We conclude that country-specific socioeconomic factors, in particular current HCE, are strongly associated with survival of patients who experience severe aGvHD.
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http://dx.doi.org/10.3389/fimmu.2020.01537DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7390847PMC
July 2020

Synonymous GATA2 mutations result in selective loss of mutated RNA and are common in patients with GATA2 deficiency.

Leukemia 2020 10 18;34(10):2673-2687. Epub 2020 Jun 18.

Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Deficiency of the transcription factor GATA2 is a highly penetrant genetic disorder predisposing to myelodysplastic syndromes (MDS) and immunodeficiency. It has been recognized as the most common cause underlying primary MDS in children. Triggered by the discovery of a recurrent synonymous GATA2 variant, we systematically investigated 911 patients with phenotype of pediatric MDS or cellular deficiencies for the presence of synonymous alterations in GATA2. In total, we identified nine individuals with five heterozygous synonymous mutations: c.351C>G, p.T117T (N = 4); c.649C>T, p.L217L; c.981G>A, p.G327G; c.1023C>T, p.A341A; and c.1416G>A, p.P472P (N = 2). They accounted for 8.2% (9/110) of cases with GATA2 deficiency in our cohort and resulted in selective loss of mutant RNA. While for the hotspot mutation (c.351C>G) a splicing error leading to RNA and protein reduction was identified, severe, likely late stage RNA loss without splicing disruption was found for other mutations. Finally, the synonymous mutations did not alter protein function or stability. In summary, synonymous GATA2 substitutions are a new common cause of GATA2 deficiency. These findings have broad implications for genetic counseling and pathogenic variant discovery in Mendelian disorders.
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http://dx.doi.org/10.1038/s41375-020-0899-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7515837PMC
October 2020

Favorable outcomes of hematopoietic stem cell transplantation in children and adolescents with Diamond-Blackfan anemia.

Blood Adv 2020 04;4(8):1760-1769

Robert Debré Hospital, Groupe Hospitalier, Assistance Publique-Hôpitaux de Paris Nord, Université de Paris, Paris, France.

Diamond-Blackfan anemia (DBA) is a congenital pure red cell aplasia associated with congenital abnormalities and cancer predisposition. Allogeneic hematopoietic stem cell transplantation (HSCT) can correct the hematological phenotype and is indicated in transfusion-dependent patients. In 70 children reported to the German DBA and French HSCT registries, HSCT was performed from 1985 to 2017. Median age at HSCT was 5.5 years (range, 0.9-17.3 years). Two-thirds of patients (64%) were transplanted from a matched sibling donor (MSD), and most procedures were performed after the year 1999 (73%). Primary engraftment was achieved in all patients. One patient developed secondary graft failure. Cumulative incidence of acute graft-versus-host disease (GVHD) was 24% for °II-IV (95% confidence interval [CI], 16% to 37%) and 7% for °III-IV (95% CI, 3% to 17%); cumulative incidence of chronic GVHD was 11% (95% CI, 5% to 22%). The probability of chronic GVHD-free survival (cGFS) was 87% (95% CI, 79% to 95%) and significantly improved over time (<2000: 68% [95% CI, 47% to 89%] vs ≥2000: 94% [95% CI, 87% to 100%], P < .01). cGFS was comparable following HSCT from a MSD and an unrelated donor (UD). Of note, no severe chronic GVHD or deaths were reported following MSD-HSCT after 1999. The difference of cGFS in children transplanted <10 years of age compared with older patients did not reach statistical significance (<10 years: 90% [95% CI, 81% to 99%] vs 10-18 years 78% [95% CI, 58% to 98%]). In summary, these data indicate that HSCT is efficient and safe in young DBA patients and should be considered if a MSD or matched UD is available. HSCT for transfusion dependency only must be critically discussed in older patients.
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http://dx.doi.org/10.1182/bloodadvances.2019001210DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7189291PMC
April 2020

Loss of the Fanconi anemia-associated protein NIPA causes bone marrow failure.

J Clin Invest 2020 06;130(6):2827-2844

Department of Internal Medicine I, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Inherited bone marrow failure syndromes (IBMFSs) are a heterogeneous group of disorders characterized by defective hematopoiesis, impaired stem cell function, and cancer susceptibility. Diagnosis of IBMFS presents a major challenge due to the large variety of associated phenotypes, and novel, clinically relevant biomarkers are urgently needed. Our study identified nuclear interaction partner of ALK (NIPA) as an IBMFS gene, as it is significantly downregulated in a distinct subset of myelodysplastic syndrome-type (MDS-type) refractory cytopenia in children. Mechanistically, we showed that NIPA is major player in the Fanconi anemia (FA) pathway, which binds FANCD2 and regulates its nuclear abundance, making it essential for a functional DNA repair/FA/BRCA pathway. In a knockout mouse model, Nipa deficiency led to major cell-intrinsic defects, including a premature aging phenotype, with accumulation of DNA damage in hematopoietic stem cells (HSCs). Induction of replication stress triggered a reduction in and functional decline of murine HSCs, resulting in complete bone marrow failure and death of the knockout mice with 100% penetrance. Taken together, the results of our study add NIPA to the short list of FA-associated proteins, thereby highlighting its potential as a diagnostic marker and/or possible target in diseases characterized by hematopoietic failure.
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http://dx.doi.org/10.1172/JCI126215DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7260023PMC
June 2020

TIM-3 deficiency presenting with two clonally unrelated episodes of mesenteric and subcutaneous panniculitis-like T-cell lymphoma and hemophagocytic lymphohistiocytosis.

Pediatr Blood Cancer 2020 06 14;67(6):e28302. Epub 2020 Apr 14.

Institute for Immunodeficiency, Center for Chronic Immunodeficiency (CCI), Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

This report offers novel clinical and diagnostic aspects of the association between germline mutations in HAVCR2 and subcutaneous panniculitis-like T-cell lymphoma (SPTCL). The patient presented with panniculitis-like T-cell lymphoma involving mesenteric fatty tissue associated with hemophagocytic lymphohistiocytosis (HLH). Five years later, he developed a clonally unrelated SPTCL and underwent hematopoietic stem cell transplantation. Retrospectively, he was found to carry germline mutations in HAVCR2 associated with reduced T-cell immunoglobulin mucin-3 (TIM-3) expression. We show that mesenteric fatty tissue localization of SPTCL can be the presenting manifestation of TIM-3 deficiency, that this condition predisposes to recurrent lymphoma, and that flow cytometry is a possible screening tool.
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http://dx.doi.org/10.1002/pbc.28302DOI Listing
June 2020

Oncogenic Kras causes myeloproliferation via NLRP3 inflammasome activation.

Nat Commun 2020 04 3;11(1):1659. Epub 2020 Apr 3.

Department of Medicine I, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Oncogenic Ras mutations occur in various leukemias. It was unclear if, besides the direct transforming effect via constant RAS/MEK/ERK signaling, an inflammation-related effect of KRAS contributes to the disease. Here, we identify a functional link between oncogenic Kras and NLRP3 inflammasome activation in murine and human cells. Mice expressing active Kras in the hematopoietic system developed myeloproliferation and cytopenia, which is reversed in Kras mice lacking NLRP3 in the hematopoietic system. Therapeutic IL-1-receptor blockade or NLRP3-inhibition reduces myeloproliferation and improves hematopoiesis. Mechanistically, Kras-RAC1 activation induces reactive oxygen species (ROS) production causing NLRP3 inflammasome-activation. In agreement with our observations in mice, patient-derived myeloid leukemia cells exhibit KRAS/RAC1/ROS/NLRP3/IL-1β axis activity. Our findings indicate that oncogenic KRAS not only act via its canonical oncogenic driver function, but also enhances the activation of the pro-inflammatory RAC1/ROS/NLRP3/IL-1β axis. This paves the way for a therapeutic approach based on immune modulation via NLRP3 blockade in KRAS-mutant myeloid malignancies.
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http://dx.doi.org/10.1038/s41467-020-15497-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7125138PMC
April 2020

Genotype-phenotype association and variant characterization in Diamond-Blackfan anemia caused by pathogenic variants in RPL35A.

Haematologica 2020 04 2. Epub 2020 Apr 2.

Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Rockville, MD, USA;

Diamond Blackfan anemia (DBA) is predominantly an autosomal dominant inherited red cell aplasia primarily caused by pathogenic germline variants in ribosomal protein genes. DBA due to pathogenic RPL35A variants has been associated with large 3q29 deletions and phenotypes not common in DBA. We conducted a multi-institutional genotype-phenotype study of 45 patients with DBA associated with pathogenic RPL35A germline variants and curated the variant data on 21 additional cases from the literature. Genotype-phenotype analyses were conducted comparing patients with large deletions versus all other pathogenic variants in RPL35A. Twenty-two of the 45 cases had large deletions in RPL35A. After adjusting for multiple tests, a statistically significant association was observed between patients with a large deletion and steroid-resistant anemia, neutropenia, craniofacial abnormalities, chronic gastrointestinal problems, and intellectual disabilities (p<0.01) compared with all other pathogenic variants. Non-large deletion pathogenic variants were spread across RPL35A with no apparent hot spot and 56% of the individual family variants were observed more than once. In this, the largest known study of DBA patients with pathogenic RPL35A variants, we determined that patients with large deletions have a more severe phenotype that is clinically different from those with non-large deletion variants. Genes of interest also deleted in the 3q29 region that could be associated with some of these phenotypic features include LMLN and IQCG. Management of DBA due to large RPL35A deletions may be challenging due to complex problems and require comprehensive assessments by multiple specialists including immunologic, gastrointestinal, and developmental evaluations to provide optimal multidisciplinary care.
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http://dx.doi.org/10.3324/haematol.2020.246629DOI Listing
April 2020

Noonan syndrome-associated myeloproliferative disorder with somatically acquired monosomy 7: impact on clinical decision making.

Br J Haematol 2019 11 15;187(4):E83-E86. Epub 2019 Oct 15.

Division of Paediatric Haematology-Oncology and Stem Cell Transplantation, Department of Paediatrics, Ghent University Hospital, Ghent, Belgium.

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http://dx.doi.org/10.1111/bjh.16191DOI Listing
November 2019

Hematopoietic stem cell transplantation for children with acute myeloid leukemia-results of the AML SCT-BFM 2007 trial.

Leukemia 2020 02 2;34(2):613-624. Epub 2019 Oct 2.

Department of Pediatrics, Division of Pediatric Hematology and Oncology, University of Düsseldorf, Düsseldorf, Germany.

AML SCT-BFM 2007 was the first hematopoietic stem cell transplantation (HCT) trial in Germany to comply with the European Clinical Trials Directive, and aimed to standardize pediatric HCT for acute myeloid leukemia (AML) across centers in Germany, Austria, and the Czech Republic. Children with high-risk features and a good early response achieving a complete first remission (CR-1) and those in CR-2 after a first relapse were stratified to receive HCT from a matched donor after myeloablative conditioning consisting of busulfan, cyclophosphamide, and melphalan. Four-year EFS and OS were 61 and 70%. Cumulative incidence of relapse (CIR) was 22%. TRM was 15% and correlated with age reaching 9% (SE 3%) in children younger than 12 years and 31% (SE 9%) in older children and adolescents. Children with poorly responding primary disease or relapse were allocated to receive early HCT after a cytoreductive regimen with fludarabine, amsacrine, and cytarabine, followed by reduced intensity conditioning and prophylactic donor lymphocyte infusions. Four-year EFS and OS were 49 and 53%. CIR was 38% and TRM 11%. For patients with primary poor response disease, early use of RIC HCT followed by prophylactic DLI can induce long-term remissions in more than 50% (EFS 46% (SE 9%)).
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http://dx.doi.org/10.1038/s41375-019-0584-8DOI Listing
February 2020

Sustained remission with azacitidine monotherapy and an aberrant precursor B-lymphoblast population in juvenile myelomonocytic leukemia.

Pediatr Blood Cancer 2019 10 28;66(10):e27905. Epub 2019 Jun 28.

Department of Pediatrics, Section of Hematology Oncology, Texas Children's Hospital/Baylor College of Medicine, Houston, Texas.

Juvenile myelomonocytic leukemia (JMML) has a poor prognosis in general, with hematopoietic stem cell transplant (HSCT) remaining the standard of care for cure. The hypomethylating agent, azacitidine, has been used as a bridging therapy to transplant. However, no patients have been treated with azacitidine without an HSCT post azacitidine. We report on an infant with JMML with somatic KRAS G12A mutation and monosomy 7 who achieved sustained remission following azacitidine monotherapy. He also developed an aberrant B-lymphoblast population which declined with similar kinetics as his JMML-associated abnormalities, suggesting that a B-lymphoblast population in JMML does not always progress to acute leukemia.
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http://dx.doi.org/10.1002/pbc.27905DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7328527PMC
October 2019

Next-generation reference intervals for pediatric hematology.

Clin Chem Lab Med 2019 Sep;57(10):1595-1607

Department of Pediatrics and Adolescent Medicine, University Hospital Erlangen, Erlangen, Germany.

Background Interpreting hematology analytes in children is challenging due to the extensive changes in hematopoiesis that accompany physiological development and lead to pronounced sex- and age-specific dynamics. Continuous percentile charts from birth to adulthood allow accurate consideration of these dynamics. However, the ethical and practical challenges unique to pediatric reference intervals have restricted the creation of such percentile charts, and limitations in current approaches to laboratory test result displays restrict their use when guiding clinical decisions. Methods We employed an improved data-driven approach to create percentile charts from laboratory data collected during patient care in 10 German centers (9,576,910 samples from 358,292 patients, 412,905-1,278,987 samples per analyte). We demonstrate visualization of hematology test results using percentile charts and z-scores (www.pedref.org/hematology) and assess the potential of percentiles and z-scores to support diagnosis of different hematological diseases. Results We created percentile charts for hemoglobin, hematocrit, red cell indices, red cell count, red cell distribution width, white cell count and platelet count in girls and boys from birth to 18 years of age. Comparison of pediatricians evaluating complex clinical scenarios using percentile charts versus conventional/tabular representations shows that percentile charts can enhance physician assessment in selected example cases. Age-specific percentiles and z-scores, compared with absolute test results, improve the identification of children with blood count abnormalities and the discrimination between different hematological diseases. Conclusions The provided reference intervals enable precise assessment of pediatric hematology test results. Representation of test results using percentiles and z-scores facilitates their interpretation and demonstrates the potential of digital approaches to improve clinical decision-making.
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http://dx.doi.org/10.1515/cclm-2018-1236DOI Listing
September 2019

Impaired human hematopoiesis due to a cryptic intronic splicing mutation.

J Exp Med 2019 05 26;216(5):1050-1060. Epub 2019 Mar 26.

Division of Hematology/Oncology, The Manton Center for Orphan Disease Research, Boston Children's Hospital and Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA

Studies of allelic variation underlying genetic blood disorders have provided important insights into human hematopoiesis. Most often, the identified pathogenic mutations result in loss-of-function or missense changes. However, assessing the pathogenicity of noncoding variants can be challenging. Here, we characterize two unrelated patients with a distinct presentation of dyserythropoietic anemia and other impairments in hematopoiesis associated with an intronic mutation in that is 24 nucleotides upstream of the canonical splice acceptor site. Functional studies demonstrate that this single-nucleotide alteration leads to reduced canonical splicing and increased use of an alternative splice acceptor site that causes a partial intron retention event. The resultant altered GATA1 contains a five-amino acid insertion at the C-terminus of the C-terminal zinc finger and has no observable activity. Collectively, our results demonstrate how altered splicing of GATA1, which reduces levels of the normal form of this master transcription factor, can result in distinct changes in human hematopoiesis.
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http://dx.doi.org/10.1084/jem.20181625DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6504223PMC
May 2019

Azacitidine is effective for targeting leukemia-initiating cells in juvenile myelomonocytic leukemia.

Leukemia 2019 07 24;33(7):1805-1810. Epub 2019 Jan 24.

Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

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http://dx.doi.org/10.1038/s41375-018-0343-2DOI Listing
July 2019

Juvenile myelomonocytic leukemia: who's the driver at the wheel?

Blood 2019 03 22;133(10):1060-1070. Epub 2019 Jan 22.

Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Juvenile myelomonocytic leukemia (JMML) is a unique clonal hematopoietic disorder of early childhood. It is classified as an overlap myeloproliferative/myelodysplastic neoplasm by the World Health Organization and shares some features with chronic myelomonocytic leukemia in adults. JMML pathobiology is characterized by constitutive activation of the Ras signal transduction pathway. About 90% of patients harbor molecular alterations in 1 of 5 genes (, , , , or ), which define genetically and clinically distinct subtypes. Three of these subtypes, -, -, and -mutated JMML, are characterized by heterozygous somatic gain-of-function mutations in nonsyndromic children, whereas 2 subtypes, JMML in neurofibromatosis type 1 and JMML in children with CBL syndrome, are defined by germline Ras disease and acquired biallelic inactivation of the respective genes in hematopoietic cells. The clinical course of the disease varies widely and can in part be predicted by age, level of hemoglobin F, and platelet count. The majority of children require allogeneic hematopoietic stem cell transplantation for long-term leukemia-free survival, but the disease will eventually resolve spontaneously in ∼15% of patients, rendering the prospective identification of these cases a clinical necessity. Most recently, genome-wide DNA methylation profiles identified distinct methylation signatures correlating with clinical and genetic features and highly predictive for outcome. Understanding the genomic and epigenomic basis of JMML will not only greatly improve precise decision making but also be fundamental for drug development and future collaborative trials.
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http://dx.doi.org/10.1182/blood-2018-11-844688DOI Listing
March 2019

JMML genomics and decisions.

Hematology Am Soc Hematol Educ Program 2018 11;2018(1):307-312

Department of Pediatrics and Adolescent Medicine, University Children's Hospital, University of Freiburg, Freiburg, Germany.

Juvenile myelomonocytic leukemia (JMML) is a unique clonal hematopoietic disorder of early childhood characterized by hyperactivation of the RAS signal transduction pathway. Approximately 90% of patients harbor molecular alteration in 1 of 5 genes (), which define genetically and clinically distinct JMML subtypes. Three subtypes, , and -mutated JMML, are characterized by heterozygous somatic gain-of-function mutations in non syndromic children, while two subtypes, JMML in neurofibromatosis type 1 and in JMML in children with CBL syndrome, are characterized by germ line RAS disease and acquired biallelic inactivation of the respective tumor suppressor genes in hematopoietic cells. In addition to the initiating RAS pathway lesion, secondary genetic alterations within and outside of the RAS pathway are detected in about half the patients. Most recently, genome-wide DNA methylation profiles identified distinct methylation signatures correlating with clinical and genetic features and highly predictive of outcome. JMML is a stem cell disorder, and most JMML patients require allogeneic stem cell transplantation for long-term survival. However, spontaneous disease regression is noted in the majority of children with -mutated JMML and in some -mutated cases. In the absence of 1 of the 5 canonical RAS pathway alteration, rare mutations in other RAS genes and non-JMML myeloproliferative disorders need to be excluded. Understanding the genetic basis of myeloproliferative disorders in early childhood will greatly improve clinical decision making.
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http://dx.doi.org/10.1182/asheducation-2018.1.307DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6245977PMC
November 2018

THROMBOTECT - a randomized study comparing low molecular weight heparin, antithrombin and unfractionated heparin for thromboprophylaxis during induction therapy of acute lymphoblastic leukemia in children and adolescents.

Haematologica 2019 04 27;104(4):756-765. Epub 2018 Sep 27.

Department of Pediatrics, Christian-Albrechts-University Kiel and University Medical Center Schleswig-Holstein, Kiel, Germany.

Thromboembolism is a serious complication of induction therapy for childhood acute lymphoblastic leukemia. We prospectively compared the efficacy and safety of antithrombotic interventions in the consecutive leukemia trials ALL-BFM 2000 and AIEOP-BFM ALL 2009. Patients with newly diagnosed acute lymphoblastic leukemia (n=949, age 1 to 18 years) were randomized to receive low-dose unfractionated heparin, prophylactic low molecular weight heparin (enoxaparin) or activity-adapted antithrombin throughout induction therapy. The primary objective of the study was to determine whether enoxaparin or antithrombin reduces the incidence of thromboembolism as compared to unfractionated heparin. The principal safety outcome was hemorrhage; leukemia outcome was a secondary endpoint. Thromboembolism occurred in 42 patients (4.4%). Patients assigned to unfractionated heparin had a higher risk of thromboembolism (8.0%) compared with those randomized to enoxaparin (3.5%; =0.011) or antithrombin (1.9%; <0.001). The proportion of patients who refused antithrombotic treatment as allocated was 3% in the unfractionated heparin or antithrombin arms, and 33% in the enoxaparin arm. Major hemorrhage occurred in eight patients (no differences between the groups). The 5-year event-free survival was 80.9±2.2% among patients assigned to antithrombin compared to 85.9±2.0% in the unfractionated heparin group (=0.06), and 86.2±2.0% in the enoxaparin group (=0.10). In conclusion, prophylactic use of antithrombin or enoxaparin significantly reduced thromboembolism. Despite the considerable number of patients rejecting the assigned treatment with subcutaneous injections, the result remains unambiguous. Thromboprophylaxis - for the present time primarily with enoxaparin - can be recommended for children and adolescents with acute lymphoblastic leukemia during induction therapy. Whether and how antithrombin may affect leukemia outcome remains to be determined.
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http://dx.doi.org/10.3324/haematol.2018.194175DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6442986PMC
April 2019

Monosomy 7 in Pediatric Myelodysplastic Syndromes.

Hematol Oncol Clin North Am 2018 Aug;32(4):729-743

Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Faculty of Medicine, Medical Center, University of Freiburg, Mathildenstr.1, Freiburg 79106, Germany; German Cancer Consortium (DKTK), Freiburg, Germany.

Myelodysplastic syndromes (MDS) in children and adolescents are a rare heterogeneous group of clonal stem cell disorders. Complete or partial loss of chromosome 7 constitutes the most common cytogenetic abnormality encountered in any type of childhood MDS, is associated with more advanced disease, and usually requires a timely allogeneic stem cell transplantation. This article provides insights into the current understanding of the genotype, phenotype, and clonal evolution patterns in pediatric MDS associated with loss of chromosome 7.
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http://dx.doi.org/10.1016/j.hoc.2018.04.007DOI Listing
August 2018

Protection from UV light is an evolutionarily conserved feature of the haematopoietic niche.

Nature 2018 06 13;558(7710):445-448. Epub 2018 Jun 13.

Department of Stem Cell and Regenerative Biology and Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA.

Haematopoietic stem and progenitor cells (HSPCs) require a specific microenvironment, the haematopoietic niche, which regulates HSPC behaviour. The location of this niche varies across species, but the evolutionary pressures that drive HSPCs to different microenvironments remain unknown. The niche is located in the bone marrow in adult mammals, whereas it is found in other locations in non-mammalian vertebrates, for example, in the kidney marrow in teleost fish. Here we show that a melanocyte umbrella above the kidney marrow protects HSPCs against ultraviolet light in zebrafish. Because mutants that lack melanocytes have normal steady-state haematopoiesis under standard laboratory conditions, we hypothesized that melanocytes above the stem cell niche protect HSPCs against ultraviolet-light-induced DNA damage. Indeed, after ultraviolet-light irradiation, unpigmented larvae show higher levels of DNA damage in HSPCs, as indicated by staining of cyclobutane pyrimidine dimers and have reduced numbers of HSPCs, as shown by cmyb (also known as myb) expression. The umbrella of melanocytes associated with the haematopoietic niche is highly evolutionarily conserved in aquatic animals, including the sea lamprey, a basal vertebrate. During the transition from an aquatic to a terrestrial environment, HSPCs relocated into the bone marrow, which is protected from ultraviolet light by the cortical bone around the marrow. Our studies reveal that melanocytes above the haematopoietic niche protect HSPCs from ultraviolet-light-induced DNA damage in aquatic vertebrates and suggest that during the transition to terrestrial life, ultraviolet light was an evolutionary pressure affecting the location of the haematopoietic niche.
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http://dx.doi.org/10.1038/s41586-018-0213-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6093292PMC
June 2018

Author Correction: The landscape of genomic alterations across childhood cancers.

Nature 2018 07;559(7714):E10

Hopp-Children's Cancer Center at the NCT Heidelberg (KiTZ), Heidelberg, Germany.

In this Article, author Benedikt Brors was erroneously associated with affiliation number '8' (Department of Developmental Neurobiology, St Jude Children's Research Hospital, Memphis, Tennessee, USA); the author's two other affiliations (affiliations '3' and '7', both at the German Cancer Research Center (DKFZ)) were correct. This has been corrected online.
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http://dx.doi.org/10.1038/s41586-018-0167-2DOI Listing
July 2018