Publications by authors named "Ondrej Hrusak"

62 Publications

Somatic Mutations in Oncogenes Are in Chronic Myeloid Leukemia Acquired Deregulated Base-Excision Repair and Alternative Non-Homologous End Joining.

Front Oncol 2021 20;11:744373. Epub 2021 Sep 20.

Institute of Hematology and Blood Transfusion, Prague, Czechia.

Somatic mutations are a common molecular mechanism through which chronic myeloid leukemia (CML) cells acquire resistance to tyrosine kinase inhibitors (TKIs) therapy. While most of the mutations in the kinase domain of BCR-ABL1 can be successfully managed, the recurrent somatic mutations in other genes may be therapeutically challenging. Despite the major clinical relevance of mutation-associated resistance in CML, the mechanisms underlying mutation acquisition in TKI-treated leukemic cells are not well understood. This work demonstrated acquisition of mutations on isolated single-cell sorted CML clones growing in the presence of imatinib. The acquisition of mutations was associated with the significantly increased expression of the and genes involved in the error-prone alternative nonhomologous end-joining pathway, leading to genomic instability, and increased expression of the , and genes involved in the base-excision repair (long patch) pathway, allowing point mutagenesis. This work showed and that acquisition of resistance-associated mutations in oncogenes is the prevalent method of somatic mutation development in CML under TKIs treatment.
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http://dx.doi.org/10.3389/fonc.2021.744373DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8488388PMC
September 2021

Early-onset pulmonary and cutaneous vasculitis driven by constitutively active SRC-family kinase HCK.

J Allergy Clin Immunol 2021 Sep 15. Epub 2021 Sep 15.

Department of Pediatrics, 2nd Faculty of Medicine, Charles University, and University Hospital Motol, Prague, Czech Republic.

Background: Inborn errors of immunity (IEI) are genetic disorders characterized by various degrees of immune dysregulation that can manifest as immune deficiency, autoimmunity or autoinflammation. The routine use of next-generation sequencing in the clinic has facilitated the identification of an ever-increasing number of IEI, revealing the roles of immunologically important genes in human pathologies. However, despite this progress, treatment is still extremely challenging.

Objective: We report a new monogenic autoinflammatory disorder caused by a de novo activating mutation, p.Tyr515*, in hematopoietic cell kinase (HCK). The disease is characterized by cutaneous vasculitis and chronic pulmonary inflammation that progresses to fibrosis.

Methods: Whole-exome sequencing, Sanger sequencing, mass spectrometry and western blotting were performed to identify and characterize the pathogenic HCK mutation. Dysregulation of mutant HCK was confirmed ex vivo in primary cells and in vitro in transduced cell lines.

Results: Mutant HCK lacking the C-terminal inhibitory tyrosine Tyr522 exhibited increased kinase activity and enhanced myeloid cell priming, migration and effector functions, such as production of the inflammatory cytokines IL-1β, IL-6, IL-8 and TNFα and production of reactive oxygen species. These aberrant functions were reflected by inflammatory leukocyte infiltration of the lungs and skin. Moreover, an overview of the clinical course of the disease, including therapies, provides evidence for the therapeutic efficacy of the Janus kinase (JAK) 1/2 inhibitor ruxolitinib in inflammatory lung disease.

Conclusion: We propose HCK-driven pulmonary and cutaneous vasculitis as a novel autoinflammatory disorder of IEI.
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http://dx.doi.org/10.1016/j.jaci.2021.07.046DOI Listing
September 2021

Novel class of ZNF384 aberrations in acute leukemia.

Blood Adv 2021 Sep 16. Epub 2021 Sep 16.

CLIP, University Hospital Motol, Czech Republic.

Fusion of the ZNF384 gene as the 3' partner to several different 5' partner genes occurs recurrently in B-cell precursor acute lymphoblastic and mixed phenotype B/myeloid leukemia. These canonical fusions (ZNF384r) contain the complete ZNF384 coding sequence and are associated with a specific gene expression signature. Cases with this signature, but without canonical ZNF384 fusions (ZNF384r-like cases), have been described previously. Though some have been shown to harbor ZNF362 fusions, the primary aberrations remain unknown in a major proportion. We studied three patients with the ZNF384r signature and unknown primary genetic background and identified a previously unknown class of genetic aberration affecting the last exon of ZNF384 and resulting in disruption of the C-terminal portion of the ZNF384 protein. Importantly, in two cases, the ZNF384 aberration - indel - was missed during the bioinformatic analysis but revealed by the manual, targeted reanalysis. Two cases with the novel aberrations had a mixed (B/myeloid) immunophenotype commonly associated with canonical ZNF384 fusions. In conclusion, we present leukemia cases with a novel class of ZNF384 aberrations that phenocopy leukemia with ZNF384r. Therefore, we show that part of the so-called ZNF384r-like cases represent the same genetic subtype as leukemia with canonical ZNF384 fusions.
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http://dx.doi.org/10.1182/bloodadvances.2021005318DOI Listing
September 2021

Effect of Blinatumomab vs Chemotherapy on Event-Free Survival Among Children With High-risk First-Relapse B-Cell Acute Lymphoblastic Leukemia: A Randomized Clinical Trial.

JAMA 2021 03;325(9):843-854

Charité-Universitätsmedizin Berlin, Berlin, Germany.

Importance: Blinatumomab is a CD3/CD19-directed bispecific T-cell engager molecule with efficacy in children with relapsed or refractory B-cell acute lymphoblastic leukemia (B-ALL).

Objective: To evaluate event-free survival in children with high-risk first-relapse B-ALL after a third consolidation course with blinatumomab vs consolidation chemotherapy before allogeneic hematopoietic stem cell transplant.

Design, Setting, And Participants: In this randomized phase 3 clinical trial, patients were enrolled November 2015 to July 2019 (data cutoff, July 17, 2019). Investigators at 47 centers in 13 countries enrolled children older than 28 days and younger than 18 years with high-risk first-relapse B-ALL in morphologic complete remission (M1 marrow, <5% blasts) or with M2 marrow (blasts ≥5% and <25%) at randomization.

Intervention: Patients were randomized to receive 1 cycle of blinatumomab (n = 54; 15 μg/m2/d for 4 weeks, continuous intravenous infusion) or chemotherapy (n = 54) for the third consolidation.

Main Outcomes And Measures: The primary end point was event-free survival (events: relapse, death, second malignancy, or failure to achieve complete remission). The key secondary efficacy end point was overall survival. Other secondary end points included minimal residual disease remission and incidence of adverse events.

Results: A total of 108 patients were randomized (median age, 5.0 years [interquartile range {IQR}, 4.0-10.5]; 51.9% girls; 97.2% M1 marrow) and all patients were included in the analysis. Enrollment was terminated early for benefit of blinatumomab in accordance with a prespecified stopping rule. After a median of 22.4 months of follow-up (IQR, 8.1-34.2), the incidence of events in the blinatumomab vs consolidation chemotherapy groups was 31% vs 57% (log-rank P < .001; hazard ratio [HR], 0.33 [95% CI, 0.18-0.61]). Deaths occurred in 8 patients (14.8%) in the blinatumomab group and 16 (29.6%) in the consolidation chemotherapy group. The overall survival HR was 0.43 (95% CI, 0.18-1.01). Minimal residual disease remission was observed in more patients in the blinatumomab vs consolidation chemotherapy group (90% [44/49] vs 54% [26/48]; difference, 35.6% [95% CI, 15.6%-52.5%]). No fatal adverse events were reported. In the blinatumomab vs consolidation chemotherapy group, the incidence of serious adverse events was 24.1% vs 43.1%, respectively, and the incidence of adverse events greater than or equal to grade 3 was 57.4% vs 82.4%. Adverse events leading to treatment discontinuation were reported in 2 patients in the blinatumomab group.

Conclusions And Relevance: Among children with high-risk first-relapse B-ALL, treatment with 1 cycle of blinatumomab compared with standard intensive multidrug chemotherapy before allogeneic hematopoietic stem cell transplant resulted in an improved event-free survival at a median of 22.4 months of follow-up.

Trial Registration: ClinicalTrials.gov Identifier: NCT02393859.
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http://dx.doi.org/10.1001/jama.2021.0987DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7926287PMC
March 2021

DUX4r, ZNF384r and PAX5-P80R mutated B-cell precursor acute lymphoblastic leukemia frequently undergo monocytic switch.

Haematologica 2021 08 1;106(8):2066-2075. Epub 2021 Aug 1.

CLIP-Dpt.of Paediatric Haematology/Oncology, Charles University, Prague, Czech Republic.

Recently, we described B-cell precursor acute lymphoblastic leukemia (BCP-ALL) subtype with early switch to the monocytic lineage and loss of the B-cell immunophenotype, including CD19 expression. Thus far, the genetic background has remained unknown. Among 726 children consecutively diagnosed with BCP-ALL, 8% patients experienced switch detectable by flow cytometry (FC). Using exome and RNA sequencing, switch was found to positively correlate with three different genetic subtypes: PAX5-P80R mutation (5 cases with switch out of 5), rearranged DUX4 (DUX4r; 30 cases of 41) and rearranged ZNF384 (ZNF384r; 4 cases of 10). Expression profiles or phenotypic patterns correlated with genotypes, but within each genotype they could not identify cases who subsequently switched. If switching was not taken into account, the B-cell-oriented FC assessment underestimated the minimal residual disease level. For patients with PAX5-P80R, a discordance between FC-determined and PCR-determined MRD was found on day 15, resulting from a rapid loss of the B-cell phenotype. Discordance on day 33 was observed in all the DUX4r, PAX5-P80R and ZNF384r subtypes. Importantly, despite the substantial phenotypic changes, possibly even challenging the appropriateness of BCP-ALL therapy, the monocytic switch was not associated with a higher incidence of relapse and poorer prognosis in patients undergoing standard ALL treatment.
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http://dx.doi.org/10.3324/haematol.2020.250423DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8327733PMC
August 2021

Flash survey on severe acute respiratory syndrome coronavirus-2 infections in paediatric patients on anticancer treatment.

Eur J Cancer 2020 06 7;132:11-16. Epub 2020 Apr 7.

The Cancer Centre for Children, The Children's Hospital at Westmead, Australia.

Introduction: Since the beginning of COVID-19 pandemic, it is known that the severe course of the disease occurs mostly among the elderly, whereas it is rare among children and young adults. Comorbidities, in particular, diabetes and hypertension, clearly associated with age, besides obesity and smoke, are strongly associated with the need for intensive treatment and a dismal outcome. A weaker immunity of the elderly has been proposed as a possible explanation of this uneven age distribution. Thus, there is concern that children treated for cancer may allso be at risk for an unfavourable course of infection. Along the same line, anecdotal information from Wuhan, China, mentioned a severe course of COVID-19 in a child treated for leukaemia.

Aim And Methods: We made a flash survey on COVID-19 incidence and severity among children on anticancer treatment. Respondents were asked by email to fill in a short Web-based survey.

Results: We received reports from 25 countries, where approximately 10,000 patients at risk are followed up. At the time of the survey, more than 200 of these children were tested, nine of whom were positive for COVID-19. Eight of the nine cases had asymptomatic to mild disease, and one was just diagnosed with COVID-19. We also discuss preventive measures that are in place or should be taken and treatment options in immunocompromised children with COVID-19.

Conclusion: Thus, even children receiving anticancer chemotherapy may have a mild or asymptomatic course of COVID-19. While we should not underestimate the risk of developing a more severe course of COVID-19 than that observed here, the intensity of preventive measures should not cause delays or obstructions in oncological treatment.
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http://dx.doi.org/10.1016/j.ejca.2020.03.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7141482PMC
June 2020

Comprehensive Molecular Profiling for Relapsed/Refractory Pediatric Burkitt Lymphomas-Retrospective Analysis of Three Real-Life Clinical Cases-Addressing Issues on Randomization and Customization at the Bedside.

Front Oncol 2019 7;9:1531. Epub 2020 Feb 7.

Department of Pediatric Oncology, University Hospital Brno and Faculty of Medicine, Masaryk University, Brno, Czechia.

In order to identify reasons for treatment failures when using targeted therapies, we have analyzed the comprehensive molecular profiles of three relapsed, poor-prognosis Burkitt lymphoma cases. All three cases had resembling clinical presentation and histology and all three patients relapsed, but their outcomes differed significantly. The samples of their tumor tissue were analyzed using whole-exome sequencing, gene expression profiling, phosphoproteomic assays, and single-cell phosphoflow cytometry. These results explain different treatment responses of the three histologically identical but molecularly different tumors. Our findings support a personalized approach for patient with high risk, refractory, and rare diseases and may contribute to personalized and customized treatment efforts for patients with limited treatment options like relapsed/refractory Burkitt lymphoma.

Summary: The main aim of this study is to analyze three relapsed Burkitt lymphoma patients using a comprehensive molecular profiling, in order to explain their different outcomes and to propose a biomarker-based targeted treatment. In cases 1 and 3, the tumor tissue and the host were analyzed prospectively and appropriate target for the treatment was successfully implemented; however, in case 2, analyses become available only retrospectively and his empirically based rescue treatment did not hit the right target of his disease.
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http://dx.doi.org/10.3389/fonc.2019.01531DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7027364PMC
February 2020

Cytometric analysis of cell suspension generated by cavitron ultrasonic surgical aspirator in pediatric brain tumors.

J Neurooncol 2019 May 2;143(1):15-25. Epub 2019 Mar 2.

CLIP - Childhood Leukaemia Investigation Prague, Prague, Czech Republic.

Purpose: The aim of this study was to test the possibility of using specimens obtained by a cavitron ultrasonic surgical aspirator (CUSA) in flow and mass cytometry investigations of pediatric brain tumors.

Methods: CUSA specimens obtained from 19 pediatric patients with brain tumors were investigated. Flow and mass cytometry methods were applied to analyze the composition of material collected using the CUSA. Cell suspensions were prepared from CUSA aspirates. Then sample viability was assessed by conventional flow cytometry and subsequently stained with a panel of 31 metal-labeled antibodies.

Results: Viability assessment was performed using conventional flow cytometry. Viability of cells in the acquired samples was below 50% in 16 of 19 cases. A mass cytometry investigation and subsequent analysis enabled us to discriminate brain tumor cells from contaminating leukocytes, whose proportions varied across the specimens. The addition of the viability marker cisplatin directly into the mass cytometry panel gave the means to selecting viable cells only for subsequent analyses. The proportion of non-viable cells was higher among tumor cells compared leukocytes.

Conclusions: When the analysis of the tumor cell immunophenotype is performed with markers for determining viability, the expression of the investigated markers can be evaluated. Suitable markers can be selected by high-throughput methods, such as mass cytometry, and those that are diagnostically relevant can be investigated using flow cytometry, which is more flexible in terms of time.
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http://dx.doi.org/10.1007/s11060-019-03135-wDOI Listing
May 2019

Genomic landscape of pediatric B-other acute lymphoblastic leukemia in a consecutive European cohort.

Haematologica 2019 07 10;104(7):1396-1406. Epub 2019 Jan 10.

CLIP - Childhood Leukaemia Investigation Prague

Novel biological subtypes and clinically important genetic aberrations (druggable lesions, prognostic factors) have been described in B-other acute lymphoblastic leukemia (ALL) during the last decade; however, due to a lack of studies on unselected cohorts, their population frequency and mutual associations still have to be established. We studied 110 consecutively diagnosed and uniformly treated childhood B-other patients using single nucleotide polymorphism arrays and whole exome/transcriptome sequencing. The frequency of -rearranged, -like, -rearranged, -like, iAMP21 and -rearranged subtypes was 27%, 15%, 5%, 5%, 4%, and 2%, respectively; 43% of cases were not classified into any of these subtypes (B-rest). We found worse early response to treatment in -rearranged leukemia and a strong association of -rearranged leukemia with B-myeloid immunophenotype. Of the druggable lesions, JAK/STAT-class and RAS/RAF/MAPK-class aberrations were found in 21% and 43% of patients, respectively; an ABL-class aberration was found in one patient. A recently described negative prognostic factor, , was found in 14% of patients and was enriched in (but not exclusive for) -like subtype. fusions (including 4 novel), intragenic amplifications and P80R mutations were mutually exclusive and only occurred in the B-rest subset, altogether accounting for 20% of the B-other group. P80R was associated with a specific gene expression signature, potentially defining a novel leukemia subtype. Our study shows unbiased European population-based frequencies of novel ALL subtypes, recurrent (cyto)genetic aberrations and their mutual associations. This study also strengthens and widens the current knowledge of B-other ALL and provides an objective basis for optimization of current genetic diagnostics.
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http://dx.doi.org/10.3324/haematol.2018.204974DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6601078PMC
July 2019

Next-generation amplicon TRB locus sequencing can overcome limitations of flow-cytometric Vβ expression analysis and confirms clonality in all T-cell prolymphocytic leukemia cases.

Cytometry A 2018 11 10;93(11):1118-1124. Epub 2018 Nov 10.

Medical Department II, Unit for Hema-tological Diagnostics, University Hospital Schleswig-Holstein, Kiel, Germany.

T-cell receptor (TCR) β repertoire analysis can distinguish monoclonal from polyclonal T-cell proliferations and crucially aid in the diagnosis of T-cell malignancies. TCR repertoire can be assessed either by flow cytometry (FCM), or by molecular genetic techniques. We compared the results of parallel analyses of Vβ expression by FCM and TRB rearrangements by DNA-based next-generation sequencing (NGS) in 80 diagnostic peripheral blood samples of patients with T-cell prolymphocytic leukemia (T-PLL) for (1) the diagnosis of clonality and (2) the assessment of dominant Vβ usage. FCM-based analysis of the surface expression was performed using the IOTest Beta Mark kit. The NGS-based analysis employed the multiplex Biomed-2 VB-JB primers. In all the samples, one or two clonal TRB rearrangements were detected by NGS. Although a dominant Vβ domain usage was detected by FCM in only 41/80 (51%) samples, clonality was suspected in all of them. In a total of 12 cases, the FCM missed the clone detected by NGS, despite theoretical coverage by the antibodies, the functionality of the rearrangement, and the expression of TCRαβ on the cell surface. Partly overlapping with those cases, FCM discovered predominant Vβ usage in the T-PLL population that differed from the one detected by NGS in 10 cases. Overall, the concordant NGS and FCM results were obtained on 61/80 (76%) of samples. We conclude that NGS-based TRB analysis can overcome certain limitations of FCM-based analysis by the identification of both productive and nonproductive rearrangements and by covering the whole Vβ spectrum. Currently available FCM analysis of Vβ expression lacks this breadth but has advantages, such as parallel immunophenotyping and a more accurate quantification of the Vβ usage. © 2018 International Society for Advancement of Cytometry.
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http://dx.doi.org/10.1002/cyto.a.23604DOI Listing
November 2018

The genetic basis and cell of origin of mixed phenotype acute leukaemia.

Nature 2018 10 12;562(7727):373-379. Epub 2018 Sep 12.

Johns Hopkins Medical Institutions, Baltimore, MD, USA.

Mixed phenotype acute leukaemia (MPAL) is a high-risk subtype of leukaemia with myeloid and lymphoid features, limited genetic characterization, and a lack of consensus regarding appropriate therapy. Here we show that the two principal subtypes of MPAL, T/myeloid (T/M) and B/myeloid (B/M), are genetically distinct. Rearrangement of ZNF384 is common in B/M MPAL, and biallelic WT1 alterations are common in T/M MPAL, which shares genomic features with early T-cell precursor acute lymphoblastic leukaemia. We show that the intratumoral immunophenotypic heterogeneity characteristic of MPAL is independent of somatic genetic variation, that founding lesions arise in primitive haematopoietic progenitors, and that individual phenotypic subpopulations can reconstitute the immunophenotypic diversity in vivo. These findings indicate that the cell of origin and founding lesions, rather than an accumulation of distinct genomic alterations, prime tumour cells for lineage promiscuity. Moreover, these findings position MPAL in the spectrum of immature leukaemias and provide a genetically informed framework for future clinical trials of potential treatments for MPAL.
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http://dx.doi.org/10.1038/s41586-018-0436-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6195459PMC
October 2018

International cooperative study identifies treatment strategy in childhood ambiguous lineage leukemia.

Blood 2018 07 2;132(3):264-276. Epub 2018 May 2.

National Program for Antineoplastic Drugs for Children (PINDA), Chilean National Pediatric Oncology Group, Hospital Roberto del Rio/Universidad de Chile, Santiago, Chile.

Despite attempts to improve the definitions of ambiguous lineage leukemia (ALAL) during the last 2 decades, general therapy recommendations are missing. Herein, we report a large cohort of children with ALAL and propose a treatment strategy. A retrospective multinational study (International Berlin-Frankfurt-Münster Study of Leukemias of Ambiguous Lineage [iBFM-AMBI2012]) of 233 cases of pediatric ALAL patients is presented. Survival statistics were used to compare the prognosis of subsets and types of treatment. Five-year event-free survival (EFS) of patients with acute lymphoblastic leukemia (ALL)-type primary therapy (80% ± 4%) was superior to that of children who received acute myeloid leukemia (AML)-type or combined-type treatment (36% ± 7.2% and 50% ± 12%, respectively). When ALL- or AML-specific gene fusions were excluded, 5-year EFS of CD19 leukemia was 83% ± 5.3% on ALL-type primary treatment compared with 0% ± 0% and 28% ± 14% on AML-type and combined-type primary treatment, respectively. Superiority of ALL-type treatment was documented in single-population mixed phenotype ALAL (using World Health Organization and/or European Group for Immunophenotyping of Leukemia definitions) and bilineal ALAL. Treatment with ALL-type protocols is recommended for the majority of pediatric patients with ALAL, including cases with CD19 ALAL. AML-type treatment is preferred in a minority of ALAL cases with CD19 and no other lymphoid features. No overall benefit of transplantation was documented, and it could be introduced in some patients with a poor response to treatment. As no clear indicator was found for a change in treatment type, this is to be considered only in cases with ≥5% blasts after remission induction. The results provide a basis for a prospective trial.
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http://dx.doi.org/10.1182/blood-2017-12-821363DOI Listing
July 2018

Recent advances in the management of pediatric acute lymphoblastic leukemia.

F1000Res 2016 4;5:2635. Epub 2016 Nov 4.

Department of Pediatric Hematology and Oncology, 2nd Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic.

Acute lymphoblastic leukemia (ALL) is the most common malignancy in childhood. Despite enormous improvement of prognosis during the last half century, ALL remains a major cause of childhood cancer-related mortality. During the past decade, whole genomic methods have enhanced our knowledge of disease biology. Stratification of therapy according to early treatment response measured by minimal residual disease allows risk group assignment into different treatment arms, ranging from reduction to intensification of treatment. Progress has been achieved in academic clinical trials by optimization of combined chemotherapy, which continues to be the mainstay of contemporary treatment. The availability of suitable volunteer main histocompatibility antigen-matched unrelated donors has increased the rates of hematopoietic stem cell transplantation (HSCT) over the past two decades. Allogeneic HSCT has become an alternative treatment for selected, very-high-risk patients. However, intensive treatment burdens children with severe acute toxic effects that can cause permanent organ damage and even toxic death. Immunotherapeutic approaches have recently come to the forefront in ALL therapy. Monoclonal antibodies blinatumomab and inotuzumab ozogamicin as well as gene-modified T cells directed to specific target antigens have shown efficacy against resistant/relapsed leukemia in phase I/II studies. Integration of these newer modalities into combined regimens with chemotherapy may rescue a subset of children not curable by contemporary therapy. Another major challenge will be to incorporate less toxic regimens into the therapy of patients with low-risk disease who have a nearly 100% chance of being cured, and the ultimate goal is to improve their quality of life while maintaining a high cure rate.
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http://dx.doi.org/10.12688/f1000research.9548.1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5642309PMC
November 2016

ETV6/RUNX1-like acute lymphoblastic leukemia: A novel B-cell precursor leukemia subtype associated with the CD27/CD44 immunophenotype.

Genes Chromosomes Cancer 2017 08 5;56(8):608-616. Epub 2017 May 5.

CLIP-Childhood Leukaemia Investigation Prague, Czech Republic.

We have shown previously that ETV6/RUNX1-positive acute lymphoblastic leukemia (ALL) is distinguishable from other ALL subtypes by CD27 /CD44 immunophenotype. During diagnostic immunophenotyping of 573 childhood B-cell precursor ALL (BCP-ALL), we identified eight cases with this immunophenotype among "B-other ALL" (BCP-ALL cases negative for routinely tested chromosomal/genetic aberrations). We aimed to elucidate whether these cases belong to the recently described ETV6/RUNX1-like ALL defined by the ETV6/RUNX1-specific gene expression profile (GEP), harboring concurrent ETV6 and IKZF1 lesions. We performed comprehensive genomic analysis using single nucleotide polymorphism arrays, whole exome and transcriptome sequencing and GEP on microarrays. In unsupervised hierarchical clustering based on GEP, five out of seven analyzed CD27 /CD44 B-other cases clustered with ETV6/RUNX1-positive ALL and were thus classified as ETV6/RUNX1-like ALL. The two cases clustering outside ETV6/RUNX1-positive ALL harbored a P2RY8/CRLF2 fusion with activating JAK2 mutations and a TCF3/ZNF384 fusion, respectively, assigning them to other ALL subtypes. All five ETV6/RUNX1-like cases harbored ETV6 deletions; uniform intragenic ARPP21 deletions and various IKZF1 lesions were each found in three ETV6/RUNX1-like cases. The frequency of ETV6 and ARPP21 deletions was significantly higher in ETV6/RUNX1-like ALL compared with a reference cohort of 42 B-other ALL. In conclusion, we show that ETV6/RUNX1-like ALL is associated with CD27 /CD44 immunophenotype and identify ARPP21 deletions to contribute to its specific genomic profile enriched for ETV6 and IKZF1 lesions. In conjunction with previously published data, our study identifies the ETV6 lesion as the only common genetic aberration and thus the most likely key driver of ETV6/RUNX1-like ALL.
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http://dx.doi.org/10.1002/gcc.22464DOI Listing
August 2017

AIEOP-BFM consensus guidelines 2016 for flow cytometric immunophenotyping of Pediatric acute lymphoblastic leukemia.

Cytometry B Clin Cytom 2018 01 21;94(1):82-93. Epub 2017 Feb 21.

Laboratory of Pediatric Onco-Hematology, Women and Child Department, University of Padova, Padova, Italy.

Immunophenotyping by flow cytometry (FCM) is a worldwide mainstay in leukemia diagnostics. For concordant multicentric application, however, a gap exists between available classification systems, technologic standardization, and clinical needs. The AIEOP-BFM consortium induced an extensive standardization and validation effort between its nine national reference laboratories collaborating in immunophenotyping of pediatric acute lymphoblastic leukemia (ALL). We elaborated common guidelines which take advantage of the possibilities of multi-color FCM: marker panel requirements, immunological blast gating, in-sample controls, tri-partite antigen expression rating (negative vs. weak or strong positive) with capturing of blast cell heterogeneities and subclone formation, refined ALL subclassification, and a dominant lineage assignment algorithm able to distinguish "simple" from bilineal/"complex" mixed phenotype acute leukemia (MPAL) cases, which is essential for choice of treatment. These guidelines are a first step toward necessary inter-laboratory standardization of pediatric leukemia immunophenotyping for a concordant multicentric application. © 2017 International Clinical Cytometry Society.
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http://dx.doi.org/10.1002/cyto.b.21518DOI Listing
January 2018

Common Variable Immunodeficiency patients with a phenotypic profile of immunosenescence present with thrombocytopenia.

Sci Rep 2017 01 5;7:39710. Epub 2017 Jan 5.

CLIP - Childhood Leukemia Investigation Prague, Department of Paediatric Haematology and Oncology, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic.

Common variable immunodeficiency (CVID) is a heterogeneous group of diseases. Our aim was to define sub-groups of CVID patients with similar phenotypes and clinical characteristics. Using eight-color flow cytometry, we analyzed both B- and T-cell phenotypes in a cohort of 88 CVID patients and 48 healthy donors. A hierarchical clustering of probability binning "bins" yielded a separate cluster of 22 CVID patients with an abnormal phenotype. We showed coordinated proportional changes in naïve CD4+ T-cells (decreased), intermediate CD27- CD28+ CD4+ T-cells (increased) and CD21low B-cells (increased) that were stable for over three years. Moreover, the lymphocytes' immunophenotype in this patient cluster exhibited features of profound immunosenescence and chronic activation. Thrombocytopenia was only found in this cluster (36% of cases, manifested as Immune Thrombocytopenia (ITP) or Evans syndrome). Clinical complications more frequently found in these patients include lung fibrosis (in 59% of cases) and bronchiectasis (55%). The degree of severity of these symptoms corresponded to more deviation from normal levels with respect to CD21low B-cells, naïve CD4+ and CD27− CD28+ CD4+ T-cells. Next-generation sequencing did not reveal any common genetic background. We delineate a subgroup of CVID patients with activated and immunosenescent immunophenotype of lymphocytes and distinct set of clinical complications without common genetic background.
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http://dx.doi.org/10.1038/srep39710DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5214528PMC
January 2017

Standardized flow cytometry for highly sensitive MRD measurements in B-cell acute lymphoblastic leukemia.

Blood 2017 01 30;129(3):347-357. Epub 2016 Nov 30.

Department of Immunology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.

A fully-standardized EuroFlow 8-color antibody panel and laboratory procedure was stepwise designed to measure minimal residual disease (MRD) in B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) patients with a sensitivity of ≤10, comparable to real-time quantitative polymerase chain reaction (RQ-PCR)-based MRD detection via antigen-receptor rearrangements. Leukocyte markers and the corresponding antibodies and fluorochromes were selected based on their contribution in separating BCP-ALL cells from normal/regenerating BCP cells in multidimensional principal component analyses. After 5 multicenter design-test-evaluate-redesign phases with a total of 319 BCP-ALL patients at diagnosis, two 8-color antibody tubes were selected, which allowed separation between normal and malignant BCP cells in 99% of studied patients. These 2 tubes were tested with a new erythrocyte bulk-lysis protocol allowing acquisition of high cell numbers in 377 bone marrow follow-up samples of 178 BCP-ALL patients. Comparison with RQ-PCR-based MRD data showed a clear positive relation between the percentage concordant cases and the number of cells acquired. For those samples with >4 million cells acquired, concordant results were obtained in 93% of samples. Most discordances were clarified upon high-throughput sequencing of antigen-receptor rearrangements and blind multicenter reanalysis of flow cytometric data, resulting in an unprecedented concordance of 98% (97% for samples with MRD < 0.01%). In conclusion, the fully standardized EuroFlow BCP-ALL MRD strategy is applicable in >98% of patients with sensitivities at least similar to RQ-PCR (≤10), if sufficient cells (>4 × 10, preferably more) are evaluated.
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http://dx.doi.org/10.1182/blood-2016-07-726307DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5291958PMC
January 2017

Lymphocyte enrichment using CD81-targeted immunoaffinity matrix.

Cytometry A 2017 01 4;91(1):62-72. Epub 2016 Aug 4.

CLIP - Childhood Leukemia Investigation Prague, Department of Pediatric Hematology and Oncology, 2nd Faculty of Medicine, Charles University Prague and University Hospital Motol, Prague, Czech Republic.

In mass cytometry, the isolation of pure lymphocytes is very important to obtain reproducible results and to shorten the time spent on data acquisition. To prepare highly purified cell suspensions of peripheral blood lymphocytes for further analysis on mass cytometer, we used the new CD81+ immune affinity chromatography cell isolation approach. Using 21 metal conjugated antibodies in a single tube we were able to identify all basic cell subsets and compare their relative abundance in final products obtained by density gradient (Ficoll-Paque) and immune affinity chromatography (CD81+ T-catch™) isolation approach. We show that T-catch isolation approach results in purer final product than Ficoll-Paque (P values 0.0156), with fewer platelets bound to target cells. As a result acquisition time of 10 nucleated cells was 3.5 shorter. We then applied unsupervised high dimensional analysis viSNE algorithm to compare the two isolation protocols, which allowed us to evaluate the contribution of unsupervised analysis over supervised manual gating. ViSNE algorithm effectively characterized almost all supervised cell subsets. Moreover, viSNE uncovered previously overseen cell subsets and showed inaccuracies in Maxpar™ Human peripheral blood phenotyping panel kit recommended gating strategy. These findings emphasize the use of unsupervised analysis tools in parallel with conventional gating strategy to mine the complete information from a set of samples. They also stress the importance of the impurity removal to sensitively detect rare cell populations in unsupervised analysis. © 2016 International Society for Advancement of Cytometry.
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http://dx.doi.org/10.1002/cyto.a.22918DOI Listing
January 2017

Slower early response to treatment and distinct expression profile of childhood high hyperdiploid acute lymphoblastic leukaemia with DNA index < 1.16.

Genes Chromosomes Cancer 2016 09 23;55(9):727-37. Epub 2016 Jun 23.

CLIP,  Childhood Leukaemia Investigation Prague, Departmentof Paediatric Haematology and Oncology, 2nd Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic.

Acute lymphoblastic leukaemias (ALL) with 51-67 chromosomes are defined as high hyperdiploid (HHD) and are generally associated with good prognosis. However, several studies show heterogeneity in HHD ALL and suggest that the favourable prognosis is associated rather with higher ploidy defined by DNA index (DNAi) ≥ 1.16 or with a presence of specific single or combined trisomies. HHD ALL with DNAi < 1.16 are only rarely studied separately. Using single nucleotide polymorphism array, we analysed 89 childhood HHD ALL patients divided into groups with lower (<1.16; n = 34) and higher (≥1.16; n = 55) DNAi. We assessed treatment response, presence of secondary aberrations, mutations in RAS pathway genes and CREBBP and also gene expression profile (GEP) to reveal differences between the two subgroups. Cases with 51-54 chromosomes had DNAi 1.1-1.16 and cases with 55-67 chromosomes had DNAi ≥ 1.16. The groups with lower and higher DNAi had distinct response to early treatment and distinct GEP. The better response of the group with higher DNAi was associated with specific trisomies (trisomy of chromosome 10 or combined with trisomies 4 and/or 17). Our results suggest that cytogenetically defined HHD ALL can in fact be divided into two biologically distinguishable subgroups and that DNAi 1.16 is a relevant value to separate between the two. © 2016 Wiley Periodicals, Inc.
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http://dx.doi.org/10.1002/gcc.22374DOI Listing
September 2016

Loss of B cells and their precursors is the most constant feature of GATA-2 deficiency in childhood myelodysplastic syndrome.

Haematologica 2016 06 24;101(6):707-16. Epub 2016 Mar 24.

CLIP-Department of Pediatric Hematology and Oncology, 2 Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic Department of Pediatric Hematology and Oncology, 2 Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic

GATA-2 deficiency was recently described as common cause of overlapping syndromes of immunodeficiency, lymphedema, familiar myelodysplastic syndrome or acute myeloid leukemia. The aim of our study was to analyze bone marrow and peripheral blood samples of children with myelodysplastic syndrome or aplastic anemia to define prevalence of the GATA2 mutation and to assess whether mutations in GATA-2 transcription factor exhibit specific immunophenotypic features. The prevalence of a GATA2 mutation in a consecutively diagnosed cohort of children was 14% in advanced forms of myelodysplastic syndrome (refractory anemia with excess blasts, refractory anemia with excess blasts in transformation, and myelodysplasia-related acute myeloid leukemia), 17% in refractory cytopenia of childhood, and 0% in aplastic anemia. In GATA-2-deficient cases, we found the most profound B-cell lymphopenia, including its progenitors in blood and bone marrow, which correlated with significantly diminished intronRSS-Kde recombination excision circles in comparison to other myelodysplastic syndrome/aplastic anemia cases. The other typical features of GATA-2 deficiency (monocytopenia and natural killer cell lymphopenia) were less discriminative. In conclusion, we suggest screening for GATA2 mutations in pediatric myelodysplastic syndrome, preferentially in patients with impaired B-cell homeostasis in bone marrow and peripheral blood (low number of progenitors, intronRSS-Kde recombination excision circles and naïve cells).
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http://dx.doi.org/10.3324/haematol.2015.137711DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5013954PMC
June 2016

High-resolution Antibody Array Analysis of Childhood Acute Leukemia Cells.

Mol Cell Proteomics 2016 Apr 19;15(4):1246-61. Epub 2016 Jan 19.

From the ‡CLIP - Childhood Leukaemia Investigation Prague, Department of Paediatric Haematology and Oncology, 2 Faculty of Medicine, Charles University in Prague, V Uvalu 84, 15006 Prague 5, Czech Republic;

Acute leukemia is a disease pathologically manifested at both genomic and proteomic levels. Molecular genetic technologies are currently widely used in clinical research. In contrast, sensitive and high-throughput proteomic techniques for performing protein analyses in patient samples are still lacking. Here, we used a technology based on size exclusion chromatography followed by immunoprecipitation of target proteins with an antibody bead array (Size Exclusion Chromatography-Microsphere-based Affinity Proteomics, SEC-MAP) to detect hundreds of proteins from a single sample. In addition, we developed semi-automatic bioinformatics tools to adapt this technology for high-content proteomic screening of pediatric acute leukemia patients.To confirm the utility of SEC-MAP in leukemia immunophenotyping, we tested 31 leukemia diagnostic markers in parallel by SEC-MAP and flow cytometry. We identified 28 antibodies suitable for both techniques. Eighteen of them provided excellent quantitative correlation between SEC-MAP and flow cytometry (p< 0.05). Next, SEC-MAP was applied to examine 57 diagnostic samples from patients with acute leukemia. In this assay, we used 632 different antibodies and detected 501 targets. Of those, 47 targets were differentially expressed between at least two of the three acute leukemia subgroups. The CD markers correlated with immunophenotypic categories as expected. From non-CD markers, we found DBN1, PAX5, or PTK2 overexpressed in B-cell precursor acute lymphoblastic leukemias, LAT, SH2D1A, or STAT5A overexpressed in T-cell acute lymphoblastic leukemias, and HCK, GLUD1, or SYK overexpressed in acute myeloid leukemias. In addition, OPAL1 overexpression corresponded to ETV6-RUNX1 chromosomal translocation.In summary, we demonstrated that SEC-MAP technology is a powerful tool for detecting hundreds of proteins in clinical samples obtained from pediatric acute leukemia patients. It provides information about protein size and reveals differences in protein expression between particular leukemia subgroups. Forty-seven of SEC-MAP identified targets were validated by other conventional method in this study.
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http://dx.doi.org/10.1074/mcp.M115.054593DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4824853PMC
April 2016

Fanconi anemia with biallelic FANCD1/BRCA2 mutations - Case report of a family with three affected children.

Eur J Med Genet 2016 Mar 2;59(3):152-7. Epub 2015 Dec 2.

Department of Pediatric Hematology and Oncology, Charles University in Prague, Second Faculty of Medicine and University Hospital Motol, Prague, Czech Republic.

Fanconi anemia, complementation group D1 with bi-allelic FANCD1 (BRCA2) mutations, is a very rare genetic disorder characterized by early onset of childhood malignancies, including acute leukemia, brain cancer and nephroblastoma. Here, we present a case report of a family with 3 affected children in terms of treatment outcome, toxicity and characterization of the malignancies using comprehensive cytogenetic analysis. The first child was diagnosed with T-cell acute lymphoblastic leukemia when he was 11 months old. During chemotherapy, he suffered from repeated pancytopenia, sepsis and severe vincristine polyneuropathy, and 18 months after primary diagnosis, he succumbed to secondary acute monocytic leukemia. The second child was diagnosed with stage 2 triphasic nephroblastoma (Wilms tumor), when he was 3 years and 11 months old. During chemotherapy, he suffered from vincristine polyneuropathy. Currently, he is in complete remission, 29 months following the initial diagnosis. The third child was diagnosed with medulloblastoma with classical histology, when she was 4 years and 5 months old. After the first cycle of chemotherapy, she suffered from prolonged pancytopenia, sepsis and severe skin and mucosal toxicity. Six weeks after primary diagnosis, a first relapse in the posterior fossa was diagnosed, and at 7 and half months after primary diagnosis, a second relapse was diagnosed that led to the patient's death. Our case report underscores tumor heterogeneity, treatment toxicity and poor outcome in Fanconi anemia patients of complementation group D1.
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http://dx.doi.org/10.1016/j.ejmg.2015.11.013DOI Listing
March 2016

Appearance of cytomegalovirus-specific T-cells predicts fast resolution of viremia post hematopoietic stem cell transplantation.

Cytometry B Clin Cytom 2017 09 12;92(5):380-388. Epub 2016 Jan 12.

Department of Pediatric Hematology and Oncology, 2nd Faculty of Medicine, Charles University Prague and University Hospital Motol, V Uvalu 84, Prague, 150 06, Czech Republic.

Background: Cytomegalovirus (CMV) specific T-cells are known to provide long-term control of CMV reactivation, which is a frequent complication of hematopoietic stem cell transplantation. We have studied 58 pediatric patients after hematopoietic stem cell transplantation who suffered from CMV reactivation to reveal which functional T cell subset is best correlating with successful reactivation resolution and which protects from reactivation episode.

Methods: Detection of 30 combinatorial subsets of four types of response to ex vivo CMV stimulation (IFNγ secretion, IL-2 secretion, CD40L upregulation and degranulation) that were detectable on either CD8+ or CD4+ T cells through flow cytometry intracellular cytokine staining was used.

Results: We found that the presence of CD8+ dual positive (IFNγ+ and IL-2+) cells is the most accurate functional parameter that can predict fast resolution of CMV reactivation. Next, we show that the presence of CD8+ dual positive (IFNγ+ and IL-2+) and CD8+ IFNγ+ cells provides a protective effect (a hazard risk of 0.28 (confidence interval 0.18 - 0.43) and 0.45 (CI 0.27 - 0.75), respectively) and the presence of corticotherapy increases the risk of reactivation (HR 2.47 (CI 1.82-3.36)). Thus, a patient without corticotherapy and with both of the critical T cell subsets present has a cumulative 19.6 times lower risk of developing CMV reactivation than a patient on corticotherapy and without CD8+ dual positive (IFNγ+ and IL-2+) or CD8+ IFNγ+ cells.

Conclusions: We have established parameters of CMV specific functional response ex vivo that can be used in assisting clinical management of patients with CMV reactivation. © 2015 International Clinical Cytometry Society.
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http://dx.doi.org/10.1002/cyto.b.21348DOI Listing
September 2017

Reprogramming of B cell acute lymphoblastic leukemia cells: Do we need to shoot a moving target?

Proc Natl Acad Sci U S A 2015 Jul 11;112(27):E3455. Epub 2015 Jun 11.

Childhood Leukemia Investigation Prague (CLIP), Second Faculty of Medicine, Charles University Prague and University Hospital Motol, 150 06 Prague, Czech Republic;

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http://dx.doi.org/10.1073/pnas.1508680112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4500239PMC
July 2015
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